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1
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Zheng S, Zheng B, Fu C. The Roles of Septins in Regulating Fission Yeast Cytokinesis. J Fungi (Basel) 2024; 10:115. [PMID: 38392788 PMCID: PMC10890454 DOI: 10.3390/jof10020115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/24/2024] Open
Abstract
Cytokinesis is required to separate two daughter cells at the end of mitosis, and septins play crucial roles in many aspects of cytokinesis. While septins have been intensively studied in many model organisms, including the budding yeast Saccharomyces cerevisiae, septins have been relatively less characterized in the fission yeast Schizosaccharomyces pombe, which has proven to be an excellent model organism for studying fundamental cell biology. In this review, we summarize the findings of septins made in fission yeasts mainly from four aspects: the domain structure of septins, the localization of septins during the cell cycle, the roles of septins in regulating cytokinesis, and the regulatory proteins of septins.
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Affiliation(s)
- Shengnan Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Biyu Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Chuanhai Fu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
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2
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Devlin L, Okletey J, Perkins G, Bowen JR, Nakos K, Montagna C, Spiliotis ET. Proteomic profiling of the oncogenic septin 9 reveals isoform-specific interactions in breast cancer cells. Proteomics 2021; 21:e2100155. [PMID: 34409731 DOI: 10.1002/pmic.202100155] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/05/2021] [Indexed: 02/06/2023]
Abstract
Septins are a family of multimeric GTP-binding proteins, which are abnormally expressed in cancer. Septin 9 (SEPT9) is an essential and ubiquitously expressed septin with multiple isoforms, which have differential expression patterns and effects in breast cancer cells. It is unknown, however, if SEPT9 isoforms associate with different molecular networks and functions. Here, we performed a proteomic screen in MCF-7 breast cancer cells to identify the interactome of GFP-SEPT9 isoforms 1, 4 and 5, which vary significantly in their N-terminal extensions. While all three isoforms associated with SEPT2 and SEPT7, the truncated SEPT9_i4 and SEPT9_i5 interacted with septins of the SEPT6 group more promiscuously than SEPT9_i1, which bound predominately SEPT8. Spatial mapping and functional clustering of non-septin partners showed isoform-specific differences in interactions with proteins of distinct subcellular organelles (e.g., nuclei, centrosomes, cilia) and functions such as cell signalling and ubiquitination. The interactome of the full length SEPT9_i1 was more enriched in cytoskeletal regulators, while the truncated SEPT9_i4 and SEPT9_i5 exhibited preferential and isoform-specific interactions with nuclear, signalling, and ubiquitinating proteins. These data provide evidence for isoform-specific interactions, which arise from truncations in the N-terminal extensions of SEPT9, and point to novel roles in the pathogenesis of breast cancer.
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Affiliation(s)
- Louis Devlin
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA.,Sanofi Pasteur, Swiftwater, Pennsylvania, USA
| | - Joshua Okletey
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | | | - Jonathan R Bowen
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Konstantinos Nakos
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Cristina Montagna
- Department of Radiology & Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
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3
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Sun J, Zheng MY, Li YW, Zhang SW. Structure and function of Septin 9 and its role in human malignant tumors. World J Gastrointest Oncol 2020; 12:619-631. [PMID: 32699577 PMCID: PMC7340996 DOI: 10.4251/wjgo.v12.i6.619] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/03/2020] [Accepted: 04/25/2020] [Indexed: 02/05/2023] Open
Abstract
The treatment and prognosis of malignant tumors are closely related to the time when the tumors are diagnosed; the earlier the diagnosis of the tumor, the better the prognosis. However, most tumors are not detected in the early stages of screening and diagnosis. It is of great clinical significance to study the correlation between multiple pathogeneses of tumors and explore simple, safe, specific, and sensitive molecular indicators for early screening, diagnosis, and prognosis. The Septin 9 (SEPT9) gene has been found to be associated with a variety of human diseases, and it plays a role in the development of tumors. SEPT9 is a member of the conserved family of cytoskeletal GTPase, which consists of a P-loop-based GTP-binding domain flanked by a variable N-terminal region and a C-terminal region. SEPT9 is involved in many biological processes such as cytokinesis, polarization, vesicle trafficking, membrane reconstruction, deoxyribonucleic acid repair, cell migration, and apoptosis. Several studies have shown that SEPT9 may serve as a marker for early screening, diagnosis, and prognosis of some malignant tumors, and have the potential to become a new target for anti-cancer therapy. This article reviews the progress in research on the SEPT9 gene in early screening, diagnosis, and prognosis of tumors.
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Affiliation(s)
- Jie Sun
- Department of Pathology, Tianjin Union Medical Center, Tianjin 300121, China
| | - Min-Ying Zheng
- Department of Pathology, Tianjin Union Medical Center, Tianjin 300121, China
| | - Yu-Wei Li
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin 300121, China
| | - Shi-Wu Zhang
- Department of Pathology, Tianjin Union Medical Center, Tianjin 300121, China
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4
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Abstract
Interest in the biology of mammalian septin proteins has undergone a birth in recent years. Originally identified as critical for yeast budding throughout the 1970s, the septin family is now recognized to extend from yeast to humans and is associated with a variety of events ranging from cytokinesis to vesicle trafficking. An emerging theme for septins is their presence at sites where active membrane or cytoplasmic partitioning is occurring. Here, we briefly review the mammalian septin protein family and focus on a prototypic human and mouse septin, termed SEPT5, that is expressed in the brain, heart, and megakaryocytes. Work from neurobiology laboratories has linked SEPT5 to the exocytic complex of neurons, with implications that SEPT5 regulates neurotransmitter release. Striking similarities exist between neurotransmitter release and the platelet-release reaction, which is a critical step in platelet response to vascular injury. Work from our laboratory has characterized the platelet phenotype from mice containing a targeted deletion of SEPT5. Most strikingly, platelets from SEPT5null animals aggregate and release granular contents in response to subthreshold levels of agonists. Thus, the characterization of a SEPT5-deficient mouse has linked SEPT5 to the Platelet exocytic process and, as such, illustrates it as an important protein for regulating platelet function. Recent data suggest that platelets contain a wide repertoire of different septin proteins and assemble to form macromolecular septin complexes. The mouse platelet provides an experimental framework to define septin function in hemostasis, with implications for neurobiology and beyond.
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Affiliation(s)
- Constantino Martinez
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA
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5
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Angelis D, Spiliotis ET. Septin Mutations in Human Cancers. Front Cell Dev Biol 2016; 4:122. [PMID: 27882315 PMCID: PMC5101219 DOI: 10.3389/fcell.2016.00122] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 10/17/2016] [Indexed: 12/22/2022] Open
Abstract
Septins are GTP-binding proteins that are evolutionarily and structurally related to the RAS oncogenes. Septin expression levels are altered in many cancers and new advances point to how abnormal septin expression may contribute to the progression of cancer. In contrast to the RAS GTPases, which are frequently mutated and actively promote tumorigenesis, little is known about the occurrence and role of septin mutations in human cancers. Here, we review septin missense mutations that are currently in the Catalog of Somatic Mutations in Cancer (COSMIC) database. The majority of septin mutations occur in tumors of the large intestine, skin, endometrium and stomach. Over 25% of the annotated mutations in SEPT2, SEPT4, and SEPT9 belong to large intestine tumors. From all septins, SEPT9 and SEPT14 exhibit the highest mutation frequencies in skin, stomach and large intestine cancers. While septin mutations occur with frequencies lower than 3%, recurring mutations in several invariant and highly conserved amino acids are found across different septin paralogs and tumor types. Interestingly, a significant number of these mutations occur in the GTP-binding pocket and septin dimerization interfaces. Future studies may determine how these somatic mutations affect septin structure and function, whether they contribute to the progression of specific cancers and if they could serve as tumor-specific biomarkers.
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Fung KYY, Dai L, Trimble WS. Cell and molecular biology of septins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 310:289-339. [PMID: 24725429 DOI: 10.1016/b978-0-12-800180-6.00007-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Septins are a family of GTP-binding proteins that assemble into cytoskeletal filaments. Unlike other cytoskeletal components, septins form ordered arrays of defined stoichiometry that can polymerize into long filaments and bundle laterally. Septins associate directly with membranes and have been implicated in providing membrane stability and serving as diffusion barriers for membrane proteins. In addition, septins bind other proteins and have been shown to function as multimolecular scaffolds by recruiting components of signaling pathways. Remarkably, septins participate in a spectrum of cellular processes including cytokinesis, ciliogenesis, cell migration, polarity, and cell-pathogen interactions. Given their breadth of functions, it is not surprising that septin abnormalities have also been linked to human diseases. In this review, we discuss the current knowledge of septin structure, assembly and function, and discuss these in the context of human disease.
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Affiliation(s)
- Karen Y Y Fung
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Lu Dai
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada
| | - William S Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, Canada; Department of Biochemistry, University of Toronto, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada.
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Lassen LB, Füchtbauer A, Schmitz A, Sørensen AB, Pedersen FS, Füchtbauer EM. Septin9 is involved in T-cell development and CD8+ T-cell homeostasis. Cell Tissue Res 2013; 352:695-705. [DOI: 10.1007/s00441-013-1618-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 03/11/2013] [Indexed: 12/18/2022]
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Füchtbauer A, Lassen LB, Jensen AB, Howard J, Quiroga ADS, Warming S, Sørensen AB, Pedersen FS, Füchtbauer EM. Septin9 is involved in septin filament formation and cellular stability. Biol Chem 2012; 392:769-77. [PMID: 21824004 DOI: 10.1515/bc.2011.088] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Septin9 (Sept9) is a member of the filament-forming septin family of structural proteins and is associated with a variety of cancers and with hereditary neuralgic amyotrophy. We have generated mice with constitutive and conditional Sept9 knockout alleles. Homozygous deletion of Sept9 results in embryonic lethality around day 10 of gestation whereas mice homozygous for the conditional allele develop normally. Here we report the consequences of homozygous loss of Sept9 in immortalized murine embryonic fibroblasts. Proliferation rate was not changed but cells without Sept9 had an altered morphology compared to normal cells, particularly under low serum stress. Abnormal, fragmented, and multiple nuclei were more frequent in cells without Sept9. Cell migration, as measured by gap-filling and filter-invasion assays, was impaired, but individual cells did not move less than wild-type cells. Sept9 knockout cells showed a reduced resistance to hypo-osmotic stress. Stress fiber and vinculin staining at focal adhesion points was less prominent. Long septin filaments stained for Sept7 disappeared. Instead, staining was found in short, often curved filaments and rings. Furthermore, Sept7 was no longer localized to the mitotic spindle. Together, these data reveal the importance of Sept9 for septin filament formation and general cell stability.
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9
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Hall PA, Russell SEH. Mammalian septins: dynamic heteromers with roles in cellular morphogenesis and compartmentalization. J Pathol 2011; 226:287-99. [PMID: 21990096 DOI: 10.1002/path.3024] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 10/03/2011] [Accepted: 10/03/2011] [Indexed: 02/06/2023]
Abstract
The septins are a family of GTP-binding proteins, evolutionarily conserved from yeast through to mammals, with roles in multiple core cellular functions. Here we provide an overview of our current knowledge of septin structure and function and focus mainly on mammalian septins, but gain much insight by drawing on knowledge of septins in other organisms. We describe their genomic and transcriptional complexity: a complexity manifest also in the diversity of scaffold structures that septins can form. Septin complexes can act to localize interacting proteins at specific intracellular locales and can also define membrane compartments by defining diffusion barriers. By such activities, septins can contribute to the definition of spatial asymmetry and cell polarity and we suggest a potential role in stem cell biology. Finally, we review the evidence that septins contribute to various disease states and argue that it is a breakdown in the tight regulation of their expression (particularly of individual isoforms), and also their inherent ability to oligomerize, which is pathogenic. Study of the perturbation of septin complex formation in disease will provide valuable insights into septin biology and will be a fertile ground for study.
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Affiliation(s)
- Peter A Hall
- Department of Molecular Oncology and Pathology and Laboratory Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
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10
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Connolly D, Yang Z, Castaldi M, Simmons N, Oktay MH, Coniglio S, Fazzari MJ, Verdier-Pinard P, Montagna C. Septin 9 isoform expression, localization and epigenetic changes during human and mouse breast cancer progression. Breast Cancer Res 2011; 13:R76. [PMID: 21831286 PMCID: PMC3236340 DOI: 10.1186/bcr2924] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 05/12/2011] [Accepted: 08/10/2011] [Indexed: 02/06/2023] Open
Abstract
Introduction Altered expression of Septin 9 (SEPT9), a septin coding for multiple isoform variants, has been observed in several carcinomas, including colorectal, head and neck, ovarian and breast, compared to normal tissues. The mechanisms regulating its expression during tumor initiation and progression in vivo and the oncogenic function of its different isoforms remain elusive. Methods Using an integrative approach, we investigated SEPT9 at the genetic, epigenetic, mRNA and protein levels in breast cancer. We analyzed a panel of breast cancer cell lines, human primary tumors and corresponding tumor-free areas, normal breast tissues from reduction mammoplasty patients, as well as primary mammary gland adenocarcinomas derived from the polyoma virus middle T antigen, or PyMT, mouse model. MCF7 clones expressing individual GFP-tagged SEPT9 isoforms were used to determine their respective intracellular distributions and effects on cell migration. Results An overall increase in gene amplification and altered expression of SEPT9 were observed during breast tumorigenesis. We identified an intragenic alternative promoter at which methylation regulates SEPT9_v3 expression. Transfection of specific GFP-SEPT9 isoforms in MCF7 cells indicates that these isoforms exhibit differential localization and affect migration rates. Additionally, the loss of an uncharacterized SEPT9 nucleolar localization is observed during tumorigenesis. Conclusions In this study, we found conserved in vivo changes of SEPT9 gene amplification and overexpression during human and mouse breast tumorigenesis. We show that DNA methylation is a prominent mechanism responsible for regulating differential SEPT9 isoform expression and that breast tumor samples exhibit distinctive SEPT9 intracellular localization. Together, these findings support the significance of SEPT9 as a promising tool in breast cancer detection and further emphasize the importance of analyzing and targeting SEPT9 isoform-specific expression and function.
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Affiliation(s)
- Diana Connolly
- Department of Genetics, Albert Einstein College of Medicine, Yeshiva University, 1301 Morris Park Avenue, Bronx, NY 10461, USA
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Tachibana T, Okazaki E, Yoshimi T, Azuma M, Kakehashi A, Wanibuchi H. Rat monoclonal antibody specific for septin 9. Hybridoma (Larchmt) 2010; 29:169-71. [PMID: 20443710 DOI: 10.1089/hyb.2009.0092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The septin family of GTPase proteins has been shown to be important for cell division, cytoskeletal organization, and membrane-remodeling events. Septin 9 (SEPT9) is a member of the septin family (also designated MSF/eseptin/Sint1) and has been implicated in tumorigenesis. The present study reports on the preparation and properties of a monoclonal antibody (MAb) directed against SEPT9. The antibody was produced by hybridization of mouse myeloma cells with lymph node cells from an immunized rat. The MAb 7B5 specifically recognized SEPT9, as evidenced by immunoblotting using a variety of extracts from cultured cells. In immunostaining using MAb 7B5, a filamentous pattern near the plasma membrane was observed. The MAb 7B5 promises to be useful in immunoblotting and immunostaining experiments in various cells and tissues to determine the expression levels of SEPT9, as well as to further the analysis of the biological function of this protein.
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Affiliation(s)
- Taro Tachibana
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan.
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12
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Abstract
Septins are highly conserved filamentous proteins first characterized in budding yeast and subsequently identified in must eukaryotes. Septins can bind and hydrolyze GTP, which is intrinsically related to their formation of septin hexamers and functional protein interactions. The human septin family is composed of 14 loci, SEPT1-SEPT14, which encode dozens of different septin proteins. Their central GTPase and polybasic domain regions are highly conserved but they diverge in their N-terminus and/or C-terminus. The mechanism by which the different isoforms are generated is not yet well understood, but one can hypothesize that the use of different promoters and/or alternative splicing could give rise to these variants. Septins perform diverse cellular functions according to tissue expression and their interacting partners. Functions identified to date include cell division, chromosome segregation, protein scaffolding, cellular polarity, motility, membrane dynamics, vesicle trafficking, exocytosis, apoptosis, and DNA damage response. Their expression is tightly regulated to maintain proper filament assembly and normal cellular functions. Alterations of these proteins, by mutation or expression changes, have been associated with a variety of cancers and neurological diseases. The association of septins with cancer results from alterations of expression in solid tumors or translocations in leukemias [mixed lineage leukemia (MLL)]. Expression changes in septins have also been associated with neurological conditions such as Alzheimer's and Parkinson's disease, as well as retinopathies, hepatitis C, spermatogenesis and Listeria infection. Pathogenic mutations of SEPT9 were identified in the autosomal dominant neurological disorder hereditary neuralgic amyotrophy (HNA). Human septin research over the past decade has established their importance in cell biology and human disease. Further functional characterization of septins is crucial to our understanding of their possible diagnostic, prognostic, and therapeutic applications.
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Affiliation(s)
- Esther A. Peterson
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, 48109, United States of America
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, 48109, United States of America
| | - Elizabeth M. Petty
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, 48109, United States of America
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, 48109, United States of America
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Antisense transcription in gammaretroviruses as a mechanism of insertional activation of host genes. J Virol 2010; 84:3780-8. [PMID: 20130045 DOI: 10.1128/jvi.02088-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcription of retroviruses is initiated at the U3-R region boundary in the integrated provirus and continues unidirectionally to produce genomic and mRNA products of positive polarity. Several studies have recently demonstrated the existence of naturally occurring protein-encoding transcripts of negative polarity in complex retroviruses. We report here on the identification of transcripts of negative polarity in simple murine leukemia virus (MLV). In T-cell and B-cell lymphomas induced by SL3-3 and Akv MLV, antisense transcripts initiated in the U3 region of the proviral 5' long terminal repeat (LTR) and continued into the cellular proto-oncogenes Jdp2 and Bach2 to create chimeric transcripts consisting of viral and host sequence. The phenomenon was validated in vivo using a knock-in mouse model homozygous for a single LTR at a position known to activate Nras in B-cell lymphomas. A 5' rapid amplification of cDNA ends (RACE) analysis indicated a broad spectrum of initiation sites within the U3 region of the 5' LTR. Our data show for the first time transcriptional activity of negative polarity initiating in the U3 region of simple retroviruses and suggest a novel mechanism of insertional activation of host genes. Elucidation of the nature and potential regulatory role of 5' LTR antisense transcription will be relevant to the design of therapeutic vectors and may contribute to the increasing recognition of pervasive eukaryotic transcription.
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Nielsen AA, Kjartansdóttir KR, Rasmussen MH, Sørensen AB, Wang B, Wabl M, Pedersen FS. Activation of the brain-specific neurogranin gene in murine T-cell lymphomas by proviral insertional mutagenesis. Gene 2009; 442:55-62. [PMID: 19376211 PMCID: PMC2734486 DOI: 10.1016/j.gene.2009.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Revised: 04/07/2009] [Accepted: 04/08/2009] [Indexed: 11/17/2022]
Abstract
Neurogranin (Nrgn) is a highly expressed brain-specific protein, which sequesters calmodulin at low Ca(2+)-levels. We report here on retroviral activation of the Nrgn gene in tumors induced by the T-cell lymphomagenic SL3-3 murine leukemia virus. We have performed a systematic expression analysis of Nrgn in various mouse tissues and SL3-3 induced T-cell tumors. This demonstrated that insertional activation of Nrgn increased RNA and protein expression levels to that observed in brain. Furthermore, elevated Nrgn expression was also observed in some T-cell tumors with no detected provirus integrations into this genomic region. The presented data demonstrate that Nrgn can be produced at high levels outside the brain, and suggest a novel oncogenic role in T-cell lymphomas in mice.
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Affiliation(s)
- Anne Ahlmann Nielsen
- Department of Molecular Biology, Aarhus University, C.F. Møllers Allé, Bldg. 1130, DK-8000 Aarhus C, Denmark
| | - Kristín Rós Kjartansdóttir
- Department of Molecular Biology, Aarhus University, C.F. Møllers Allé, Bldg. 1130, DK-8000 Aarhus C, Denmark
| | - Mads Heilskov Rasmussen
- Department of Molecular Biology, Aarhus University, C.F. Møllers Allé, Bldg. 1130, DK-8000 Aarhus C, Denmark
| | - Annette Balle Sørensen
- Department of Molecular Biology, Aarhus University, C.F. Møllers Allé, Bldg. 1130, DK-8000 Aarhus C, Denmark
| | - Bruce Wang
- Picobella, 863 B Mitten Road, Burlingame, California 94010, U.S.A
| | - Matthias Wabl
- Department of Microbiology and Immunology, University of California, 513 Parnassus Avenue, San Francisco, California 94143, U.S.A
| | - Finn Skou Pedersen
- Department of Molecular Biology, Aarhus University, C.F. Møllers Allé, Bldg. 1130, DK-8000 Aarhus C, Denmark
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15
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Tóth K, Galamb O, Spisák S, Wichmann B, Sipos F, Leiszter K, Molnár J, Molnár B, Tulassay Z. [Free circulating DNA based colorectal cancer screening from peripheral blood: the possibility of the methylated septin 9 gene marker]. Orv Hetil 2009; 150:969-977. [PMID: 19443305 DOI: 10.1556/oh.2009.28625] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
DNA methylation acts in early tumorigenesis. Its detection is possible either from tissue, stool or peripheral blood. Septin 9 is a sensitive methylation marker, which has been studied in several cancers such as breast and ovarian tumors and in neurological or hematological diseases. Septin proteins have an important role from cytoskeleton organisation to development of embryonal pattern. Nowadays intensive researches are going on about the relation between the septin 9 gene hypermethylation and colorectal cancer development.
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Affiliation(s)
- Kinga Tóth
- Semmelweis Egyetem, Altalános Orvostudományi Kar, II. Belgyógyászati Klinika, Budapest.
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Tooley AJ, Gilden J, Jacobelli J, Beemiller P, Trimble WS, Kinoshita M, Krummel MF. Amoeboid T lymphocytes require the septin cytoskeleton for cortical integrity and persistent motility. Nat Cell Biol 2009; 11:17-26. [PMID: 19043408 PMCID: PMC3777658 DOI: 10.1038/ncb1808] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 09/16/2008] [Indexed: 11/08/2022]
Abstract
The systems that refine actomyosin forces during motility remain poorly understood. Septins assemble on the T-cell cortex and are enriched at the mid-zone in filaments. Septin knockdown causes membrane blebbing, excess leading-edge protrusions and lengthening of the trailing-edge uropod. The associated loss of rigidity permits motility, but cells become uncoordinated and poorly persistent. This also relieves a previously unrecognized restriction to migration through small pores. Pharmacologically rigidifying cells counteracts this effect, and relieving cytoskeletal rigidity synergizes with septin depletion. These data suggest that septins tune actomyosin forces during motility and probably regulate lymphocyte trafficking in confined tissues.
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Affiliation(s)
- Aaron J Tooley
- The Department of Pathology, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0511, USA
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Characterization of a SEPT9 interacting protein, SEPT14, a novel testis-specific septin. Mamm Genome 2007; 18:796-807. [PMID: 17922164 DOI: 10.1007/s00335-007-9065-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Accepted: 08/21/2007] [Indexed: 01/08/2023]
Abstract
Septins are a highly conserved family of GTP-binding cytoskeletal proteins implicated in multiple cellular functions, including membrane transport, apoptosis, cell polarity, cell cycle regulation, cytokinesis, and oncogenesis. Here we describe the characterization of a novel interacting partner of the septin family, initially cloned from a human testis expression library following yeast two-hybrid isolation to identify SEPT9 binding partners. Upon further genomic characterization and bioinformatics analyses it was determined that this novel septin-interacting partner was also a new member of the mammalian septin family, named SEPT14. SEPT14 maps to 7p11.2 in humans and includes a conserved GTPase domain and a predicted carboxy-terminus coiled-coil domain characteristic of other septins. Three potential translational start methionines were identified by 5' RACE-PCR encoding proteins of 432-, 427-, and 425-residue peptides, respectively. SEPT14 shares closest homology to SEPT10, a human dendritic septin, and limited homology to SEPT9 isoforms. SEPT14 colocalized with SEPT9 when coexpressed in cell lines, and epitope-tagged forms of these proteins coimmunoprecipitated. Moreover, SEPT14 was coimmunoprecipitated from rat testes using SEPT9 antibodies, and yeast two-hybrid analysis suggested SEPT14 interactions with nine additional septins. Multitissue Northern blotting showed testis-specific expression of a single 5.0-kb SEPT14 transcript. RT-PCR analysis revealed that SEPT14 was not detectable in normal or cancerous ovarian, breast, prostate, bladder, or kidney cell lines and was only faintly detected in fetal liver, tonsil, and thymus samples. Interestingly, SEPT14 was expressed in testis but not testicular cancer cell lines by RT-PCR, suggesting that further investigation of SEPT14 as a testis-specific tumor suppressor is necessary.
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McDade SS, Hall PA, Russell SEH. Translational control of SEPT9 isoforms is perturbed in disease. Hum Mol Genet 2007; 16:742-52. [PMID: 17468182 DOI: 10.1093/hmg/ddm003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A common feature of the mammalian septin gene family is complex genomic architecture with multiple alternate splice variants. Septin 9 has 18 distinct transcripts encoding 15 polypeptides, with two transcripts (SEPT9_v4 and v4*) encoding the same polypeptide. We have previously reported that the ratio of these distinct transcripts is altered in neoplasia, with the v4 transcript being the usual form in normal cells but v4* becoming predominant in tumours. This led us to ask what the functional differences between these two transcripts might be. The 5'-UTRs of v4 and v4* have distinct 5' ends encoded by exons 1beta (v4) and 1zeta and 2 (v4*) and a common 3' region and initiating ATG encoded within exon 3. Here we show that the two mRNAs are translated with different efficiencies and that cellular stress can alter this. A putative internal ribosome entry site can be identified in the common region of the v4 and v4* 5'-UTRs and translation is modulated by an upstream open-reading frame in the unique region of the v4 5'-UTR. Germline mutations in hereditary neuralgic amyotrophy (HNA) map to the region which is common to the two UTRs. These mutations dramatically enhance the translational efficiency of the v4 5'-UTR, leading to elevated SEPT9_v4 protein under hypoxic conditions. Our data provide a mechanistic insight into how the HNA mutations can alter the fine control of SEPT9_v4 protein and its regulation under physiologically relevant conditions and are consistent with the episodic and stress-induced nature of the clinical features of HNA.
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Affiliation(s)
- Simon S McDade
- The Centre for Cancer Research and Cell Biology, School of Medicine and Dentistry, Queen's University Belfast, Belfast City Hospital, Belfast, UK
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19
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Wang CL, Wang BB, Bartha G, Li L, Channa N, Klinger M, Killeen N, Wabl M. Activation of an oncogenic microRNA cistron by provirus integration. Proc Natl Acad Sci U S A 2006; 103:18680-4. [PMID: 17121985 PMCID: PMC1693722 DOI: 10.1073/pnas.0609030103] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Retroviruses can cause tumors when they integrate near a protooncogene or tumor suppressor gene of the host. We infected >2,500 mice with the SL3-3 murine leukemia virus; in 22 resulting tumors, we found provirus integrations nearby or within the gene that contains the mir-17-92 microRNA (miRNA) cistron. Using quantitative real-time PCR, we showed that expression of miRNA was increased in these tumors, indicating that retroviral infection can induce expression of oncogenic miRNAs. Our results demonstrate that retroviral mutagenesis can be a potent tool for miRNA discovery.
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Affiliation(s)
- Clifford L Wang
- Department of Microbiology and Immunology, University of California-San Francisco, San Francisco, CA 94143, USA.
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20
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Ma SL, Sørensen AB, Kunder S, Sørensen KD, Quintanilla-Martinez L, Morris DW, Schmidt J, Pedersen FS. The Icsbp locus is a common proviral insertion site in mature B-cell lymphomas/plasmacytomas induced by exogenous murine leukemia virus. Virology 2006; 352:306-18. [PMID: 16780917 DOI: 10.1016/j.virol.2006.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 02/16/2006] [Accepted: 05/03/2006] [Indexed: 10/24/2022]
Abstract
ICSBP (interferon consensus sequence binding protein)/IRF8 (interferon regulatory factor 8) is an interferon gamma-inducible transcription factor expressed predominantly in hematopoietic cells, and down-regulation of this factor has been observed in chronic myelogenous leukemia and acute myeloid leukemia in man. By screening about 1200 murine leukemia virus (MLV)-induced lymphomas, we found proviral insertions at the Icsbp locus in 14 tumors, 13 of which were mature B-cell lymphomas or plasmacytomas. Only one was a T-cell lymphoma, although such tumors constituted about half of the samples screened. This indicates that the Icsbp locus can play a specific role in the development of mature B-lineage malignancies. Two proviral insertions in the last Icsbp exon were found to act by a poly(A)-insertion mechanism. The remaining insertions were found within or outside Icsbp. Since our results showed expression of Icsbp RNA and protein in all end-stage tumor samples, a simple tumor suppressor function of ICSBP is not likely. Interestingly, proviral insertions at Icsbp have not been reported from previous extensive screenings of mature B-cell lymphomas induced by endogenous MLVs. We propose that ICSBP might be involved in an early modulation of an immune response to exogenous MLVs that might also play a role in proliferation of the mature B-cell lymphomas.
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MESH Headings
- Animals
- Base Sequence
- Interferon Regulatory Factors/genetics
- Leukemia Virus, Murine/genetics
- Leukemia Virus, Murine/pathogenicity
- Lymphoma, B-Cell/etiology
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/virology
- Mice
- Plasmacytoma/etiology
- Plasmacytoma/genetics
- Plasmacytoma/pathology
- Plasmacytoma/virology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Neoplasm/genetics
- RNA, Neoplasm/metabolism
- Virus Integration/genetics
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Affiliation(s)
- Shi Liang Ma
- Department of Molecular Biology, University of Aarhus, C.F. Møllers Alle, Bldg. 130, DK-8000 Aarhus C, Denmark
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21
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Abstract
Septins are an evolutionarily conserved family of genes that encode a P loop-based GTP-binding domain flanked by a polybasic domain and (usually) a coiled-coil region. They have roles in cytokinesis, vesicle trafficking, polarity determination, and can form membrane diffusion barriers, as well as in microtubule and actin dynamics. Septins can form hetero-oligomeric complexes and possibly function as dynamic protein scaffolds. Recently, it has been shown that there are at least 13 human septin genes that exhibit extensive alternate splicing. There are complex patterns of human septin gene expression and recently it has been found that alterations in septin expression are seen in human diseases including neoplasia. This review summarises the essential properties of septins and outlines the accumulating evidence for their involvement in human neoplasia. Septins may belong to the class of cancer critical genes where alteration in expression profile (including alterations in the spectrum of transcripts expressed) may underpin their role in neoplasia as opposed to specific mutational events.
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Affiliation(s)
- S E H Russell
- Centre for Cancer Research & Cell Biology, Queen's University Belfast, University Floor, Tower Block, Belfast City Hospital, Belfast BT9 7AB, UK
| | - P A Hall
- Centre for Cancer Research & Cell Biology, Queen's University Belfast, University Floor, Tower Block, Belfast City Hospital, Belfast BT9 7AB, UK
- Centre for Cancer Research & Cell Biology, Queen's University Belfast, University Floor, Tower Block, Belfast City Hospital, Belfast BT9 7AB, UK. E-mail:
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Chacko AD, Hyland PL, McDade SS, Hamilton PW, Russell SH, Hall PA. SEPT9_v4 expression induces morphological change, increased motility and disturbed polarity. J Pathol 2005; 206:458-65. [PMID: 15902694 DOI: 10.1002/path.1794] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Several lines of evidence indicate that altered expression of SEPT9 is seen in human neoplasia. In particular there is evidence of altered expression of the SEPT9_v4 isoform. The functional consequences of this remain unclear. We have studied the expression of wild-type- and GTP-binding mutants (G144V and S148N) of the SEPT9_v4 isoform in the MCF7 cell line as a model for its deregulation in neoplasia. We find that SEPT9_v4 expression induces dramatic actin cytoskeletal reorganization with the formation of processes around the cell periphery. Expression of the SEPT9_v4 isoform and a G144V mutant cause delocalization of endogenous SEPT9 from filamentous structures but the S148N mutant does not have this effect. In addition SEPT9_v4 isoform expression enhances cell motility and is associated with perturbation of directional movement. Expression of SEPT9_v4 GTP binding mutants also has potent effects on morphology and motility and causes loss of normal polarity, as judged by Golgi reorientation assays. The phenotypes induced by expression of the SEPT9_v4 isoform and the GTP mutants provide an insight into possible mechanisms of SEPT9_v4 function and suggest that the GTPase functions have both ras- and rab-like features. We propose a model in which overexpression of the SEPT9_v4 isoform in neoplasia is associated with perturbation of SEPT9 complexes, leading to phenotypes associated with neoplasia.
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Affiliation(s)
- Alex D Chacko
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, U Floor, City Hospital, Lisburn Road, Belfast BT9 7AB, UK
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23
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Rasmussen MH, Sørensen AB, Morris DW, Dutra JC, Engelhard EK, Wang CL, Schmidt J, Pedersen FS. Tumor model-specific proviral insertional mutagenesis of the Fos/Jdp2/Batf locus. Virology 2005; 337:353-64. [PMID: 15913695 DOI: 10.1016/j.virol.2005.04.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 04/05/2005] [Accepted: 04/22/2005] [Indexed: 11/29/2022]
Abstract
Retroviral activation of the AP-1/ATF super family member Jdp2 was recently reported to be a common event in M-MLV-induced T cell lymphoma in p27-null C57x129 mice as compared to wild type-inoculated mice but has not been found important in other models. On the basis of retroviral tag retrieval from 1190 individual Akv- and SL3-3-induced lymphomas, we here report that insertional mutagenesis into the 250-kb Fos/Jdp2/Batf locus is associated with SL3-3 MLV-induced T but not Akv-induced B cell lymphomas of NMRI and SWR mice. Integration pattern and clonality analyses suggest that Jdp2 participates in SL3-3-induced tumorigenesis distinctly as compared to the M-MLV setting. Northern blot analysis showed Jdp2 to be alternatively spliced in various normal tissues as well as MLV-induced lymphomas. Interestingly, in some tumors, proviral insertion seems to activate different mRNA sub-species. Whereas elevated mRNA levels of the Fos gene could not be correlated with provirus presence, in one case, Northern blot analysis as well as quantitative real-time PCR indicated proviral activation of the AP-1 super family member Batf, a gene not previously reported to be a target of insertional mutagenesis. A novel integration cluster between Jdp2 and Batf apparently did not influence the expression level of either gene, underscoring the importance of addressing expression effects to identify target genes of insertion. Altogether, such distinct insertion patterns point to different mechanism of activation of specific proto-oncogenes and are consequently of importance for the understanding of proviral activation mechanisms as well as the specific role of individual oncogenes in tumor development.
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MESH Headings
- 3T3 Cells
- Animals
- Basic-Leucine Zipper Transcription Factors
- DNA, Neoplasm/genetics
- DNA, Neoplasm/isolation & purification
- Disease Models, Animal
- Genes, fos
- Leukemia Virus, Murine/genetics
- Lymphoma, B-Cell/genetics
- Mice
- Mice, Inbred Strains
- Mutagenesis, Insertional
- Polymerase Chain Reaction
- Proviruses/genetics
- RNA, Messenger/genetics
- RNA, Viral/genetics
- Repressor Proteins/genetics
- Retroviridae/genetics
- Thymus Gland/virology
- Transcription Factors/genetics
- Tumor Cells, Cultured
- Virus Latency
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Affiliation(s)
- M H Rasmussen
- Department of Molecular Biology, University of Aarhus, C. F. Mollers Allé, Building 130, DK-8000 Aarhus C, Denmark
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24
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Hall PA, Jung K, Hillan KJ, Russell SEH. Expression profiling the human septin gene family. J Pathol 2005; 206:269-78. [PMID: 15915442 DOI: 10.1002/path.1789] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The septins are an evolutionarily conserved family of GTP-binding proteins involved in diverse processes including vesicle trafficking, apoptosis, remodelling of the cytoskeleton, infection, neurodegeneration, and neoplasia. The present paper reports a comprehensive study of septin gene expression by DNA microarray methods in 10 360 samples of normal, diseased, and tumour tissues. A novel septin, SEPT13, has been identified and is shown to be related to SEPT7. It is shown that SEPT13 and the other known human septins are expressed in all tissue types but some show high expression in lymphoid (SEPT1, 6, 9, and 12) or brain tissues (SEPT2, 3, 4, 5, 7, 8, and 11). For a given septin, some isoforms are highly expressed in the brain and others are not. For example, SEPT8_v2 and v1, 1* and 3 are highly expressed in the brain and cluster with SEPT2, 3, 4, 5, 7, and 11. However, a probe set specific for SEPT8_v1 with low brain expression clusters away from this set. Similarly, SEPT4 has lymphoid and non-lymphoid forms; SEPT2 has lymphoid and central nervous system (CNS) forms; and SEPT6 and SEPT9 are elevated in lymphoid tissues but both have forms that cluster away from the lymphoid forms. Perturbation of septin expression was widespread in disease and tumours of the various tissues examined, particularly for conditions of the CNS, where alterations in all 13 septin genes were identified. This analysis provides a comprehensive catalogue of the septin family in health and disease. It is a key step in understanding the role of septins in physiological and pathological states and provides insight into the complexity of septin biology.
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Affiliation(s)
- Peter A Hall
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, University Floor, Tower Block, Belfast City Hospital, Belfast BT9 7AB, UK.
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25
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Scott M, Hyland PL, McGregor G, Hillan KJ, Russell SEH, Hall PA. Multimodality expression profiling shows SEPT9 to be overexpressed in a wide range of human tumours. Oncogene 2005; 24:4688-700. [PMID: 15782116 DOI: 10.1038/sj.onc.1208574] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Septins are an evolutionarily conserved family of GTPases with diverse functions including roles in cytokinesis that have been implicated in neoplasia. To address the potential role of SEPT9 in tumorigenesis, we assessed the expression of SEPT9 in 7287 fresh frozen human tissue samples and 292 human cell lines by microarray analysis. In addition, we used a sensitive RT-PCR strategy to define the expression of SEPT9 isoforms in archival formalin-fixed and paraffin-embedded normal human tissues. The mRNA data were further confirmed by immunohistological analyses of SEPT9 protein expression in normal human tissues using antisera that detect SEPT9 isoforms. Using these complementary approaches, we demonstrate that SEPT9 mRNA and protein are expressed ubiquitously, with the isoforms showing tissue-specific expression. The microarray analysis indicates that there is consistent overexpression of SEPT9 in diverse human tumours including breast, CNS, endometrium, kidney, liver, lung, lymphoid, oesophagus, ovary, pancreas, skin, soft tissue and thyroid. Since tumours are commonly associated with enhanced cell proliferation, we examined the possible correlation of Ki67 and SEPT9 expression in normal tissues and tumours. Our data indicate that the overexpression of SEPT9 in neoplasia is not simply a proliferation-associated phenomenon, despite its role in cytokinesis.
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Affiliation(s)
- Michael Scott
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, University Floor, Tower Block, Belfast City Hospital, Belfast BT9 7AB, UK
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26
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Abstract
Septins are an evolutionarily conserved group of GTP-binding and filament-forming proteins that belong to the large superclass of P-loop GTPases. While originally discovered in yeast as cell division cycle mutants with cytokinesis defects, they are now known to have diverse cellular roles which include polarity determination, cytoskeletal reorganization, membrane dynamics, vesicle trafficking, and exocytosis. Septin proteins form homo- and hetero-oligomeric polymers which can assemble into higher-order filaments. They are also known to interact with components of the cytoskeleton, ie actin and tubulin. The precise role of GTP binding is not clear but a current model suggests that it is associated with conformational changes which alter binding to other proteins. There are at least 12 human septin genes, and although information on expression patterns is limited, most undergo complex alternative splicing with some degree of tissue specificity. Nevertheless, an increasing body of data implicates the septin family in the pathogenesis of diverse disease states including neoplasia, neurodegenerative conditions, and infections. Here the known biochemical properties of mammalian septins are reviewed in the light of the data from yeast and other model organisms. The data implicating septins in human disease are considered and a model linking these data is proposed. It is posited that septins can act as regulatable scaffolds where the stoichiometry of septin associations, modifications, GTP status, and the interactions with other proteins allow the regulation of key cellular processes including polarity determination. Derangements of such septin scaffolds thus explain the role of septins in disease states.
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Affiliation(s)
- Peter A Hall
- Centre for Cancer Research & Cell Biology, Queens University Belfast, U Floor, Belfast City Hospital, Belfast BT9 7AB, UK
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27
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Abstract
Slow transforming retroviruses, such as the Moloney murine leukemia virus (M-MuLV), induce tumors upon infection of a host after a relatively long latency period. The underlying mechanism leading to cell transformation is the activation of proto-oncogenes or inactivation of tumor suppressor genes as a consequence of proviral insertions into the host genome. Cells carrying proviral insertions that confer a selective advantage will preferentially grow out. This means that proviral insertions mark genes contributing to tumorigenesis, as was demonstrated by the identification of numerous proto-oncogenes in retrovirally induced tumors in the past. Since cancer is a complex multistep process, the proviral insertions in one clone of tumor cells also represent oncogenic events that cooperate in tumorigenesis. Novel advances, such as the launch of the complete mouse genome, high-throughput isolation of proviral flanking sequences, and genetically modified animals have revolutionized proviral tagging into an elegant and efficient approach to identify signaling pathways that collaborate in cancer.
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Affiliation(s)
- Harald Mikkers
- Division of Molecular Genetics and Centre of Biomedical Genetics, Netherlands Cancer Institute 1066 CX, Amsterdam, The Netherlands
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28
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Kumagai H, Oki T, Tamitsu K, Feng SZ, Ono M, Nakajima H, Bao YC, Kawakami Y, Nagayoshi K, Copeland NG, Gilbert DJ, Jenkins NA, Kawakami T, Kitamura T. Identification and characterization of a new pair of immunoglobulin-like receptors LMIR1 and 2 derived from murine bone marrow-derived mast cells. Biochem Biophys Res Commun 2003; 307:719-29. [PMID: 12893283 DOI: 10.1016/s0006-291x(03)01245-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have identified and characterized two mouse cDNAs in a mouse antigen-stimulated bone marrow-derived mast cell cDNA library, both of which encode type I transmembrane proteins. The genes were closely mapped in the distal region of mouse chromosome 11 and expressed not only in mast cells but also widely in leukocytes. The extracellular domains of their encoded proteins contain a single variable immunoglobulin (Ig) motif sharing about 90% identity with amino acids, showing that they comprise a pair of molecules and belong to the Ig superfamily. We named these molecules leukocyte mono-Ig-like receptor1 and 2 (LMIR1 and 2). The intracellular domain of LMIR1 contains several immunoreceptor tyrosine-based inhibition motifs (ITIMs). When cross-linked, the intracellular domain was tyrosine phosphorylated and capable of recruiting tyrosine phosphatases, SHP-1 and SHP-2 and inositol polyphosphate 5-phosphatase, SHIP. LMIR2, on the other hand, contains a short cytoplasmic tail and a characteristic transmembrane domain carrying two positively charged amino acids associated with three kinds of immunoreceptor tyrosine-based activation motif (ITAM)-bearing molecules, DAP10, DAP12, and FcRgamma. These findings suggest that a new pair of ITIM/ITAM-bearing receptors, LMIR1 and 2, regulate mast cell-mediated inflammatory responses through yet to be defined ligand(s).
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Affiliation(s)
- Hidetoshi Kumagai
- Division of Hematopoietic Factors, The Advanced Clinical Research Center, The Institute of Medical Science, The University of Tokyo, 6-1 Shirokanedai-4-chome, Minato-ku, Tokyo 108-8639, Japan
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Surka MC, Tsang CW, Trimble WS. The mammalian septin MSF localizes with microtubules and is required for completion of cytokinesis. Mol Biol Cell 2002; 13:3532-45. [PMID: 12388755 PMCID: PMC129964 DOI: 10.1091/mbc.e02-01-0042] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Cytokinesis in animal cells involves the contraction of an actomyosin ring formed at the cleavage furrow. Nuclear division, or karyokinesis, must be precisely timed to occur before cytokinesis in order to prevent genetic anomalies that would result in either cell death or uncontrolled cell division. The septin family of GTPase proteins has been shown to be important for cytokinesis although little is known about their role during this process. Here we investigate the distribution and function of the mammalian septin MSF. We show that during interphase, MSF colocalizes with actin, microtubules, and another mammalian septin, Nedd5, and coprecipitates with six septin proteins. In addition, transfections of various MSF isoforms reveal that MSF-A specifically localizes with microtubules and that this localization is disrupted by nocodazole treatment. Furthermore, MSF isoforms localize primarily with tubulin at the central spindle during mitosis, whereas Nedd5 is mainly associated with actin. Microinjection of affinity-purified anti-MSF antibodies into synchronized cells, or depletion of MSF by small interfering RNAs, results in the accumulation of binucleated cells and in cells that have arrested during cytokinesis. These results reveal that MSF is required for the completion of cytokinesis and suggest a role that is distinct from that of Nedd5.
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Affiliation(s)
- Mark C Surka
- Programme in Cell Biology, Hospital for Sick Children and Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada
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30
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Yamamoto K, Shibata F, Yamaguchi M, Miura O. Fusion of MLL and MSF in adult de novo acute myelomonocytic leukemia (M4) with t(11;17)(q23;q25). Int J Hematol 2002; 75:503-7. [PMID: 12095151 DOI: 10.1007/bf02982114] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The MLL gene at chromosome band 11q23 is frequently rearranged and fused to partner genes in acute leukemias. Previously, the MSF gene, also called AF17q25, has been cloned as a fusion partner of the MLL gene in therapy-related or infant acute myelogenous leukemias with t(11;17)(q23;q25). MSF belongs to the septin family of proteins, which includes other MLL fusion partners, hCDCrel1 and Septin 6, and has also been implicated in the pathogenesis of human ovarian tumor and murine T-cell lymphoma. We describe here a 64-year-old man with de novo acute myelomonocytic leukemia (French-American-British subtype M4) with t(11;17)(q23;q25). His leukemia was successfully induced into a first remission, which, however, lasted only briefly. A second remission was never attained, and the patient died of sepsis 16 months after the diagnosis of leukemia. Examination of his leukemic cells at diagnosis revealed an MLL gene rearrangement, by Southern blotting, and an MLL-MSF fusion transcript, by the reverse transcriptase polymerase chain reaction (RT-PCR) method. Sequence analysis of the RT-PCR product further revealed that MLL exon 5 was fused in-frame to MSF exon 3. Further clinical and molecular analyses of acute leukemias with the MLL-MSF transcript may shed more light on the clinical characteristics and molecular mechanisms of the MLL-septin type leukemias.
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Affiliation(s)
- Koh Yamamoto
- Department of Hematology and Oncology, Tokyo Medical and Dental University, Japan
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Rulli K, Lenz J, Levy LS. Disruption of hematopoiesis and thymopoiesis in the early premalignant stages of infection with SL3-3 murine leukemia virus. J Virol 2002; 76:2363-74. [PMID: 11836414 PMCID: PMC135944 DOI: 10.1128/jvi.76.5.2363-2374.2002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A time course analysis of SL3-3 murine leukemia virus (SL3) infection in thymus and bone marrow of NIH/Swiss mice was performed to assess changes that occur during the early stages of progression to lymphoma. Virus was detectable in thymocytes, bone marrow, and spleen as early as 1 to 2 weeks postinoculation (p.i.). In bone marrow, virus infection was detected predominantly in immature myeloid or granulocytic cells. Flow cytometry revealed significant reductions of the Ter-119(+) and Mac-1(+) populations, and significant expansions of the Gr-1(+) and CD34(+) populations, between 2 and 4 weeks p.i. Analysis of colony-forming potential confirmed these findings. In the thymus, SL3 replication was associated with significant disruption in thymocyte subpopulation distribution between 4 and 7 weeks p.i. A significant thymic regression was observed just prior to the clonal outgrowth of tumor cells. Proviral long terminal repeats (LTRs) with increasing numbers of enhancer repeats were observed to accumulate exclusively in the thymus during the first 8 weeks p.i. Observations were compared to the early stages of infection with a virtually nonpathogenic SL3 mutant, termed SL3DeltaMyb5, which was shown by real-time PCR to be replication competent. Comparison of SL3 with SL3DeltaMyb5 implicated certain premalignant changes in tumorigenesis, including (i) increased proportions of Gr-1(+) and CD34(+) bone marrow progenitors, (ii) a significant increase in the proportion of CD4(-) CD8(-) thymocytes, (iii) thymic regression prior to tumor outgrowth, and (iv) accumulation of LTR enhancer variants. A model in which disrupted bone marrow hematopoiesis and thymopoiesis contribute to the development of lymphoma in the SL3-infected animal is discussed.
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Affiliation(s)
- Karen Rulli
- Department of Microbiology and Immunology, School of Medicine, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA
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32
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Sørensen AB, Warming S, Füchtbauer EM, Pedersen FS. Alternative splicing, expression, and gene structure of the septin-like putative proto-oncogene Sint1. Gene 2002; 285:79-89. [PMID: 12039034 DOI: 10.1016/s0378-1119(02)00406-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Sint1 (sept9), a murine gene of the septin family, was previously isolated as a putative proto-oncogene involved in T-cell lymphomagenesis. We now present its genomic structure and report on nine exons shared by all identified variants and at least four alternatively spliced 5' exons. Northern blot analyses using a Sint1 cDNA probe showed in almost all examined tissues two predominant transcripts of 3 and 4 kb. Exon-specific expression analyses assigned one of the 5' exons to the 4 kb transcript, while the other 5' exons seem to represent novel, tissue-specific, weakly expressed transcripts of different sizes, and none of them appear to hybridize to the major 3 kb transcript. Whole-mount in situ hybridization on post-implantation embryos revealed several areas strongly expressing Sint1, including neural crest cells, cephalic mesenchyme, and mesenchymal cells in the developing limb. A clustering of proviruses in four independent retrovirally induced tumors point to a region of about 3 kb around the most upstream exon as important for proviral deregulation of Sint1.
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Affiliation(s)
- Annette Balle Sørensen
- Department of Molecular and Structural Biology, University of Aarhus, DK-8000, Aarhus C, Denmark
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Abstract
Septins comprise a eukaryotic guanine nucleotide binding protein subfamily which form filamentous heteropolymer complexes. Although mechanism of cytokinesis is diverged by species and tissues, loss of septin function results in the multinuclear phenotype in many organisms. Hence septin filaments beneath the cleavage furrow are hypothesized as a structural basis to ensure completion of cytokinesis. However, molecular mechanisms of septin assembly, disassembly and function have been elusive despite the potential importance of this ubiquitous cytoskeletal system. Meanwhile, growing evidence suggests that mammalian septins functionally or physically interact with diverse molecules such as actin, actin-binding proteins, proteins of membrane fusion machinery, Cdc42 adapter proteins, a ubiquitin-protein ligase, and phosphoinositides. Careful integration of these data may provide insights into the mechanism of mammalian septin organization and functions in cytokinesis.
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Affiliation(s)
- M Kinoshita
- Department of Molecular Oncology, Kyoto University Graduate School of Medicine, Japan.
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McIlhatton MA, Burrows JF, Donaghy PG, Chanduloy S, Johnston PG, Russell SE. Genomic organization, complex splicing pattern and expression of a human septin gene on chromosome 17q25.3. Oncogene 2001; 20:5930-9. [PMID: 11593400 DOI: 10.1038/sj.onc.1204752] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2001] [Revised: 06/20/2001] [Accepted: 06/26/2001] [Indexed: 12/19/2022]
Abstract
The Ov/Br septin gene, which is also a fusion partner of MLL in acute myeloid leukaemia, is a member of a family of novel GTP binding proteins that have been implicated in cytokinesis and exocytosis. In this study, we describe the genomic and transcriptional organization of this gene, detailing seventeen exons distributed over 240 kb of sequence. Extensive database analyses identified orthologous rodent cDNAs that corresponded to new, unidentified 5' splice variants of the Ov/Br septin gene, increasing the total number of such variants to six. We report that splicing events, occurring at non-canonical sites within the body of the 3' terminal exon, remove either 1801 bp or 1849 bp of non-coding sequence and facilitate access to a secondary open reading frame of 44 amino acids maintained near the end of the 3' UTR. These events constitute a novel coding arrangement and represent the first report of such a design being implemented by a eukaryotic gene. The various Ov/Br proteins either differ minimally at their amino and carboxy termini or are equivalent to truncated versions of larger isoforms. Northern analysis with an Ov/Br septin 3' UTR probe reveals three transcripts of 4.4, 4 and 3 kb, the latter being restricted to a sub-set of the tissues tested. Investigation of the identified Ov/Br septin isoforms by RT-PCR confirms a complex transcriptional pattern, with several isoforms showing tissue-specific distribution. To date, none of the other human septins have demonstrated such transcriptional complexity.
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Affiliation(s)
- M A McIlhatton
- Department of Oncology, The Cancer Centre, Queen's University Belfast, Belfast BT9 7AB, UK
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Methner A, Leypoldt F, Joost P, Lewerenz J. Human septin 3 on chromosome 22q13.2 is upregulated by neuronal differentiation. Biochem Biophys Res Commun 2001; 283:48-56. [PMID: 11322766 DOI: 10.1006/bbrc.2001.4741] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An expression sequence tag identified in a screen for genes upregulated by retinoic acid induced neuronal differentiation of the human teratocarcinoma cell line Ntera2/D1 was found in close genomic proximity to a region of high sequence homology to the septin subfamily of GTPase genes. We could show that the tag corresponds to the 3' untranslated region of this novel gene named septin 3 and cloned three isoforms A (2191 bp), B (4378 bp), and C (1896 bp) from human Ntera2/D1 cDNA. We present the genomic localization and organization on chromosome 22q13.2, a chromosomal hot spot for translocations implicated in leukemia. Interestingly, MSF the closest paralog of septin 3 is a fusion partner in a therapy-related acute myeloid leukemia. Quantitative PCR confirmed the upregulation of the putative septin by neuronal differentiation and northern blotting showed only one band corresponding to sep3B with a neurospecific expression pattern in adult human tissues.
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Affiliation(s)
- A Methner
- Department of Neurology and Zentrum für Molekulare Neurobiologie, University Hospital Hamburg, Falkenried 94, Hamburg, D-20251, Germany.
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Yanagawa S, Lee JS, Kakimi K, Matsuda Y, Honjo T, Ishimoto A. Identification of Notch1 as a frequent target for provirus insertional mutagenesis in T-cell lymphomas induced by leukemogenic mutants of mouse mammary tumor virus. J Virol 2000; 74:9786-91. [PMID: 11000255 PMCID: PMC112415 DOI: 10.1128/jvi.74.20.9786-9791.2000] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In contrast to wild-type mouse mammary tumor virus (MMTV), the MMTV mutants with specific deletions in the U3 region of their long terminal repeats cause T-cell lymphomas. In 30% of T-cell lymphomas arising in BALB/c mice infected with MLA-MMTV, a leukemogenic MMTV mutant, we have found that MMTV proviruses were integrated into a short region of the Notch1 genome, so that truncated Notch1 transcripts encoding the transmembrane and the cytoplasmic domains of Notch1 protein could be expressed. Thus, Notch1 is a major target of provirus insertional mutagenesis in these T-cell lymphomas.
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Affiliation(s)
- S Yanagawa
- Department of Viral Oncology, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
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Jackisch BO, Hausser H, Schaefer L, Kappler J, Müller HW, Kresse H. Alternative exon usage of rat septins. Biochem Biophys Res Commun 2000; 275:180-8. [PMID: 10944462 DOI: 10.1006/bbrc.2000.3287] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Septins represent a family of phylogenetically conserved proteins required for cytokinesis. Their presence in pre- and postsynaptic neuronal membranes suggests a general function as scaffolds for membrane reorganization. The transcriptional regulation of all septins examined so far is complex, resulting in alternatively spliced variants. We focus here on the rat homologue of the gene for the human septin MSF, a truncated form of which, designated eseptin, had been described previously. It will be shown here that there is an alternative usage of the first exon by two forms, named exon r1a and r1b, respectively. Exon r1a, but not exon r1b, contains a part of the coding sequence while the start of translation for the remaining coding sequence resides in the second exon. The complete genomic organization was resolved and data on the temporal and spatial expression of this septins are presented.
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Affiliation(s)
- B O Jackisch
- Department of Internal Medicine, Institute of Physiological Chemistry and Pathobiochemistry, Münster, D-48149, Germany
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