• CXCR2
• HCC
• PAI-1
• SEPT9
• Tumor microenvironment

• ARHGEF18
• Bovine viral diarrhea virus
• NF-κB
• NS5B-palm

• Animals
• NF-kappa B/metabolism
• Cell Line
• Signal Transduction
• Diarrhea Viruses, Bovine Viral
• Rho Guanine Nucleotide Exchange Factors

• Cell junction
• Cell polarity
• PALS1
• Renal diseases
• Renal epithelia
• Tight junction

• Animals
• Mice
• Actin Cytoskeleton
• Actins
• Cytoskeleton
• Cytosol
• Epithelial Cells
• Tight Junction Proteins
• Nucleoside-Phosphate Kinase/genetics
• Membrane Proteins/genetics

• WE 2550/4-1 Deutsche Forschungsgemeinschaft
• MOE-T2EP30121-0019 Ministry of Education, Singapore

• Antibody
• Brain development
• Small GTPase
• Type I ARFs

• Animals
• Mice
• Monomeric GTP-Binding Proteins
• ADP-Ribosylation Factors/genetics
• Neurons
• Axons
• Cerebellum

• JP22H03049 Japan Society for the Promotion of Science
• JP22K19498 Japan Society for the Promotion of Science
• JP19K07059 Japan Society for the Promotion of Science

• UL1 TR004419 NCATS NIH HHS

• Cilia/metabolism
• Cytoplasm/metabolism
• Guanine Nucleotide Exchange Factors/metabolism
• Septins/genetics
• Septins/metabolism
• Signal Transduction
• rhoA GTP-Binding Protein/metabolism

• PJT-152194 CIHR
• Canadian Institutes of Health Research

• GTP-binding domain
• coiled coil
• cytoskeletal protein
• hetero-oligomeric complex
• protein filament
• septin
• structural biology

• S100A10
• SUMOylation
• cell infiltration and migration
• colorectal cancer
• polyploidy giant cancer cells

• Cleft lip/palate
• Motility
• Mutation
• Rho GTPases

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.

• Septin 9
• Malignant tumor
• Early diagnosis
• Prognosis
• Deoxyribonucleic acid methylation
• Colorectal cancer

• Cdc42
• Cell polarity
• Positive feedback
• Protein–protein interaction
• SPLIFF
• Split-ubiquitin
• Yeast

• Cell Cycle Proteins/genetics
• Cell Cycle Proteins/metabolism
• Feedback
• Guanine Nucleotide Exchange Factors
• Prospective Studies
• Saccharomyces cerevisiae/genetics
• Saccharomyces cerevisiae/metabolism
• Saccharomyces cerevisiae Proteins/genetics
• Saccharomyces cerevisiae Proteins/metabolism
• Septins/genetics
• Septins/metabolism

• RhoGEF
• axon morphology
• cortical development
• cytoskeleton
• neuronal circuit

Increasing cell mobility is the basis of tumor invasion and metastasis, and is therefore a therapeutic target for preventing the spread of many types of cancer. Septins are a family of cytoskeletal proteins with GTPase activity, and play a role in many important cellular functions, including cell migration. SEPT9 isoform 1 protein (SEPT9_i1) has been associated with breast tumor development and the enhancement of cell migration; however, the exact mechanism of how SEPT9_i1 might affect breast cancer progression remains to be elucidated. Here, we report that the expression of SEPT9_i1 positively correlated with paxillin, and both were significantly upregulated in invasive breast cancer tissues of patients with lymph node metastases. Lentivirus-mediated shRNA knockdown of SEPT9 in MCF-7 cells diminished tumor cell migration, focal adhesion (FA) maturation and the expression of β-actin, β-tubulin, Cdc42, RhoA, and Rac, whereas overexpression of SEPT9_i1 in SEPT9-knockdown MCF-7 cells promoted cell migration, FA maturation and relevant protein expression. Furthermore, overexpression of SEPT9_i1 in MCF-7 cells markedly increased FAK/Src/paxillin signaling, at least in part through RhoA/ROCK1 upstream activation. Transcriptome profiling suggested that SEPT9_i1 may directly affect “Focal adhesion” and “Regulation of actin cytoskeleton” signaling mechanisms. Finally, overexpression of SEPT9_i1 markedly enhanced lung metastases in vivo 6 weeks after tumor inoculation. These findings suggest that a mechanism of Septin-9-induced aberrant cancer cell migration is through cytoskeletal regulation and FA modulation, and encourages the use of SEPT9 as novel therapeutic target in the prevention of tumor metastasis.

CD19 is a B cell-specific receptor that regulates the threshold of B cell receptor (BCR)-mediated cell proliferation. A CD47xCD19 bispecific antibody (biAb) was generated to target and deplete B cells via multiple antibody-mediated mechanisms. Interestingly, the biAb, constructed of a CD19 binding arm and a CD47 binding arm, inhibited BCR-mediated B-cell proliferation with an effect even more potent than a CD19 monoclonal antibody (mAb). The inhibitory effect of the biAb was not attributable to CD47 binding because a monovalent or bivalent anti-CD47 mAb had no effect on B cell proliferation. Fluorescence resonance energy transfer analysis demonstrated that co-engaging CD19 and CD47 prevented CD19 clustering and its migration to BCR clusters, while only engaging CD19 (with a mAb) showed no impact on either CD19 clustering or migration. The lack of association between CD19 and the BCR resulted in decreased phosphorylation of CD19 upon BCR activation. Furthermore, the biAb differentially modulated BCR-induced gene expression compared to a CD19 mAb. Taken together, this unexpected role of CD47xCD19 co-ligation in inhibiting B cell proliferation illuminates a novel approach in which two B cell surface molecules can be tethered, to one another in order, which may provide a therapeutic benefit in settings of autoimmunity and B cell malignancies.

• Antibody therapy
• B cell proliferation
• BCR signaling
• CD19
• receptor clustering

Cells exist in dynamic three‐dimensional environments where they experience variable mechanical forces due to their interaction with the extracellular matrix, neighbouring cells and physical stresses. The ability to constantly and rapidly alter cellular behaviour in response to the mechanical environment is therefore crucial for cell viability, tissue development and homeostasis. Mechanotransduction is the process whereby cells translate mechanical inputs into biochemical signals. These signals in turn adjust cell morphology and cellular functions as diverse as proliferation, differentiation, migration and apoptosis. Here, we provide an overview of the current understanding of mechanotransduction and how septins may participate in it, drawing on their architecture and localization, their ability to directly bind and modify actomyosin networks and membranes, and their associations with the nuclear envelope.

• cytoskeleton
• mechanobiology
• septin

Actin nucleators and their binding partners play crucial roles during Salmonella invasion, but how these factors are dynamically coordinated remains unclear. Here, we show that septins, a conserved family of GTP binding proteins, play a role during the early stages of Salmonella invasion. We demonstrate that septins are rapidly enriched at sites of bacterial entry and contribute to the morphology of invasion ruffles. We found that SEPTIN2, SEPTIN7, and SEPTIN9 are required for efficient bacterial invasion. Septins contributed to the recruitment of ROCK2 kinase during Salmonella invasion, and the downstream activation of the actin nucleating protein FHOD1. In contrast, activation of the ROCK2 substrate myosin II, which is known to be required for Salmonella enterica serovar Typhimurium invasion, did not require septins. Collectively, our studies provide new insight into the mechanisms involved in Salmonella invasion of host cells.

• Salmonella enterica serovar Typhimurium
• actin
• bacterial infection
• formin
• myosin II
• septin

• ARHGEF18
• LOC100996504
• alternative transcriptional start
• granulocyte
• guanine nucleotide exchange factor
• p114-GEF

• apoptosis
• endoplasmic reticulum stress
• human osteoblastic cells line hFOB 1.19
• melatonin
• septin-7

• Actin
• Actin microtubule patterning
• Membrane-cytoskeleton crosstalk
• Microtubules
• Rho signaling
• Septins
• Spatial organization and regulation

• Actin Cytoskeleton/metabolism
• Actins/metabolism
• Animals
• Eukaryotic Cells/metabolism
• Eukaryotic Cells/physiology
• Humans
• Microtubules/metabolism
• Septins/metabolism

• R01 GM097664 NIGMS NIH HHS
• Drexel University
• National Institute of Health
• National Institute of General Medical Sciences

• CRISPR-Cas9
• F-actin
• OSBPL2
• RNA sequencing
• interactome

• Cytoskeleton
• Intracellular bacteria
• Septins
• Vacuole

• Cyclin D1
• Dysbindin-1
• Schizophrenia

• ErbB2
• endocytosis
• gastric cancer
• lysosomal degradation
• septin
• ubiquitylation

Orofacial clefts (OFCs) represent a large fraction of human birth defects and are one of the most common phenotypes affected by large copy number variants (CNVs). Due to the limited number of CNV patients in individual centers, CNV analyses of a large number of OFC patients are challenging. The present study analyzed 249 genomic deletions and 226 duplications from a cohort of 312 OFC patients reported in two publicly accessible databases of chromosome imbalance and phenotype in humans, DECIPHER and ECARUCA. Genomic regions deleted or duplicated in multiple patients were identified, and genes in these overlapping CNVs were prioritized based on the number of genes encompassed by the region and gene expression in embryonic mouse palate. Our analyses of these overlapping CNVs identified two genes known to be causative for human OFCs, SATB2 and MEIS2, and 12 genes (DGCR6, FGF2, FRZB, LETM1, MAPK3, SPRY1, THBS1, TSHZ1, TTC28, TULP4, WHSC1, WHSC2) that are associated with OFC or orofacial development. Additionally, we report 34 deleted and 24 duplicated genes that have not previously been associated with OFCs but are associated with the BMP, MAPK and RAC1 pathways. Statistical analyses show that the high number of overlapping CNVs is not due to random occurrence. The identified genes are not located in highly variable genomic regions in healthy populations and are significantly enriched for genes that are involved in orofacial development. In summary, we report a CNV analysis pipeline of a large cohort of OFC patients and identify novel candidate OFC genes.

• CIN85
• EGFR
• SEPT9
• Sorting
• Ubiquitylation

Chlamydia trachomatis is an obligate intracellular human pathogen that grows inside a membranous, cytosolic vacuole termed an inclusion. Septins are a group of 13 GTP-binding proteins that assemble into oligomeric complexes and that can form higher-order filaments. We report here that the septins SEPT2, -9, -11, and probably -7 form fibrillar structures around the chlamydial inclusion. Colocalization studies suggest that these septins combine with F actin into fibers that encase the inclusion. Targeting the expression of individual septins by RNA interference (RNAi) prevented the formation of septin fibers as well as the recruitment of actin to the inclusion. At the end of the developmental cycle of C. trachomatis, newly formed, infectious elementary bodies are released, and this release occurs at least in part through the organized extrusion of intact inclusions. RNAi against SEPT9 or against the combination of SEPT2/7/9 substantially reduced the number of extrusions from a culture of infected HeLa cells. The data suggest that a higher-order structure of four septins is involved in the recruitment or stabilization of the actin coat around the chlamydial inclusion and that this actin recruitment by septins is instrumental for the coordinated egress of C. trachomatis from human cells. The organization of F actin around parasite-containing vacuoles may be a broader response mechanism of mammalian cells to the infection by intracellular, vacuole-dwelling pathogens.

Chlamydia trachomatis is a frequent bacterial pathogen throughout the world, causing mostly eye and genital infections. C. trachomatis can develop only inside host cells; it multiplies inside a membranous vacuole in the cytosol, termed an inclusion. The inclusion is covered by cytoskeletal “coats” or “cages,” whose organization and function are poorly understood. We here report that a relatively little-characterized group of proteins, septins, is required to organize actin fibers on the inclusion and probably through actin the release of the inclusion. Septins are a group of GTP-binding proteins that can organize into heteromeric complexes and then into large filaments. Septins have previously been found to be involved in the interaction of the cell with bacteria in the cytosol. Our observation that they also organize a reaction to bacteria living in vacuoles suggests that they have a function in the recognition of foreign compartments by a parasitized human cell.

• Animals
• Embryonic Development/physiology
• Humans
• Organ Specificity
• Protein Conformation
• Protein Multimerization
• Septins/chemistry
• Septins/genetics
• Septins/physiology

• R01 GM097664 NIGMS NIH HHS
• GM097664 NIGMS NIH HHS

• ArhGEF18
• RhoA-Rock2 signaling
• apico-basal polarity
• medaka
• retina
• teleost
• vertebrate

• Animals
• Guanine Nucleotide Exchange Factors/metabolism
• Oryzias/embryology
• Oryzias/metabolism
• rho-Associated Kinases/metabolism
• rhoA GTP-Binding Protein/metabolism

• A2BP1
• antibody
• cerebral cortex
• neuron

• DMEM
• Dulbecco's modified Eagle's medium
• ERK
• FBS
• GFP
• GST
• IP
• JNK
• MAGI-1
• MAGUK
• MBP
• NGF
• PAGE
• PBS
• PC12
• PDZ
• PSD-95/Discs Large/Zona Occludens
• PTB
• RNA interference
• RNAi
• Shc
• Trk
• c-Jun N-terminal kinase
• fetal bovine serum
• glutathione S-transferase
• green fluorescent protein
• immunoprecipitation
• maltose binding protein
• membrane-associated guanylate kinase
• membrane-associated guanylate kinase with inverted organization-1
• nerve growth factor
• phosphate-buffered saline
• phosphotyrosine binding
• polyacrylamide gel electrophoresis
• tropomyosin-related kinase

• ArhGEF18
• Epithelial polarity
• Medaka
• Retina
• Rho signaling
• Teleost

In epithelial cells, myosin-II-dependent forces regulate many aspects of animal morphogenesis, such as apical constriction, cell intercalation, cell sorting, and the formation and maintenance of the adherens junction. These forces are mainly generated by the circumferential actomyosin belt, which is composed of F-actin–myosin II bundles located along apical cell–cell junctions. Although several of the molecular pathways regulating the belt have been identified, the precise mechanisms underlying its function are largely unknown. Our recent studies identified Lulu proteins (Lulu1 and Lulu2), FERM-domain-containing molecules, as the regulators of the belt. Lulus activate the circumferential actomyosin belt and thereby induce apical constriction in epithelial cells; conversely, RNAi-mediated Lulu-knockdown results in the severe disorganization of the circumferential actomyosin belt. We also showed that p114RhoGEF is a downstream molecule of Lulu2 in its regulation of the belt; Lulu2 enhances the catalytic activity of p114RhoGEF through a direct interaction and thereby activates the circumferential actomyosin belt. We further identified aPKC and Patj as regulators of Lulu2-p114RhoGEF. In this commentary, we discuss current knowledge of the circumferential actomyosin belt's regulation, focusing on the Lulu2-p114RhoGEF system.

AIM: To identify novel substrates for the mitogen-activated protein kinase-activated protein kinase 5 (MK5).

METHODS: Yeast two-hybrid screening with MK5 as bait was used to identify novel possible interaction partners. The binding of putative partner was further examined by glutathione S-transferase (GST) pull-down, co-immunoprecipitation and fluorescence resonance energy transfer (FRET) analysis. In vitro kinase and peptide array assays were used to map MK5 phosphoacceptor sites on the new partner. Confocal microscopy was performed to study the subcellular localization of MK5 and its partners.

RESULTS: Septin 8 was identified as a novel interaction partner for MK5 by yeast two-hybrid screening. This interaction was confirmed by GST pull-down, co-immunoprecipitation and FRET analysis. Septin 5, which can form a complex with septin 8, did not interact with MK5. Serine residues 242 and 271 on septin 8 were identified as in vitro MK5 phosphorylation sites. MK5 and septin 8 co-localized in the perinuclear area and in cell protrusions. Moreover, both proteins co-localized with vesicle marker synaptophysin.

CONCLUSION: Septin 8 is a bona fide interaction partner and in vitro substrate for MK5. This interaction may be implicated in vesicle trafficking.

• Mitogen-activated protein kinase-activated protein kinase-5
• Fluorescence resonance energy transfer
• Septin
• Phosphorylation
• Synaptophysin

The FERM domain–containing protein Lulu2 and p114RhoGEF function at epithelial cell–cell junctions to regulate the actomyosin belt that determines cell shape.

Myosin II–driven mechanical forces control epithelial cell shape and morphogenesis. In particular, the circumferential actomyosin belt, which is located along apical cell–cell junctions, regulates many cellular processes. Despite its importance, the molecular mechanisms regulating the belt are not fully understood. In this paper, we characterize Lulu2, a FERM (4.1 protein, ezrin, radixin, moesin) domain–containing molecule homologous to Drosophila melanogaster Yurt, as an important regulator. In epithelial cells, Lulu2 is localized along apical cell–cell boundaries, and Lulu2 depletion by ribonucleic acid interference results in disorganization of the circumferential actomyosin belt. In its regulation of the belt, Lulu2 interacts with and activates p114RhoGEF, a Rho-specific guanine nucleotide exchanging factor (GEF), at apical cell–cell junctions. This interaction is negatively regulated via phosphorylation events in the FERM-adjacent domain of Lulu2 catalyzed by atypical protein kinase C. We further found that Patj, an apical cell polarity regulator, recruits p114RhoGEF to apical cell–cell boundaries via PDZ (PSD-95/Dlg/ZO-1) domain–mediated interaction. These findings therefore reveal a novel molecular system regulating the circumferential actomyosin belt in epithelial cells.

Substitution of specific terminal subunits within septin complexes and septin phosphorylation drive the formation of distinct higher-order septin assemblies in budding yeast.

Septins are conserved guanosine triphosphate–binding cytoskeletal proteins involved in membrane remodeling. In budding yeast, five mitotic septins (Cdc3, Cdc10, Cdc11, Cdc12, and Shs1), which are essential for cytokinesis, transition during bud growth from a patch to a collar, which splits into two rings in cytokinesis and is disassembled before the next cell cycle. Cdc3, Cdc10, Cdc11, and Cdc12 form an apolar octameric rod with Cdc11 at each tip, which polymerizes into straight paired filaments. We show that Shs1 substitutes for Cdc11, resulting in octameric rods that do not polymerize into filaments but associate laterally, forming curved bundles that close into rings. In vivo, half of shs1Δ mutant cells exhibit incomplete collars and disrupted neck filaments. Importantly, different phosphomimetic mutations in Shs1 can either prevent ring formation or promote formation of a gauzelike meshwork. These results show that a single alternative terminal subunit is sufficient to confer a distinctive higher-order septin ultrastructure that can be further regulated by phosphorylation.

• Aged
• Female
• Gene Rearrangement
• Histone-Lysine N-Methyltransferase
• Humans
• Leukemia, Myeloid, Acute/genetics
• Leukemia, Myeloid, Acute/physiopathology
• Leukocytosis/etiology
• Male
• Myeloid-Lymphoid Leukemia Protein/genetics
• Oncogene Proteins, Fusion/genetics
• Septins/genetics
• Translocation, Genetic

• Cell Line
• Epithelial Cells/cytology
• Epithelial Cells/metabolism
• Fluorescence Resonance Energy Transfer
• Guanine Nucleotide Exchange Factors/genetics
• Guanine Nucleotide Exchange Factors/metabolism
• Humans
• RNA, Small Interfering/metabolism
• Recombinant Fusion Proteins/genetics
• Recombinant Fusion Proteins/metabolism
• Rho Guanine Nucleotide Exchange Factors
• Signal Transduction/physiology
• Tight Junctions/metabolism
• rhoA GTP-Binding Protein/genetics
• rhoA GTP-Binding Protein/metabolism

• 084678 Wellcome Trust
• G0400678 Medical Research Council
• BB/H002294/1 Biotechnology and Biological Sciences Research Council
• G0900098 Medical Research Council
• Wellcome Trust

Septins belong to the GTPase superclass of proteins and have been functionally implicated in cytokinesis and the maintenance of cellular morphology. They are found in all eukaryotes, except in plants. In mammals, 14 septins have been described that can be divided into four groups. It has been shown that mammalian septins can engage in homo- and heterooligomeric assemblies, in the form of filaments, which have as a basic unit a hetero-trimeric core. In addition, it has been speculated that the septin filaments may serve as scaffolds for the recruitment of additional proteins.

Here, we performed yeast two-hybrid screens with human septins 1–10, which include representatives of all four septin groups. Among the interactors detected, we found predominantly other septins, confirming the tendency of septins to engage in the formation of homo- and heteropolymeric filaments.

If we take as reference the reported arrangement of the septins 2, 6 and 7 within the heterofilament, (7-6-2-2-6-7), we note that the majority of the observed interactions respect the “group rule”, i.e. members of the same group (e.g. 6, 8, 10 and 11) can replace each other in the specific position along the heterofilament. Septins of the SEPT6 group preferentially interacted with septins of the SEPT2 group (p<0.001), SEPT3 group (p<0.001) and SEPT7 group (p<0.001). SEPT2 type septins preferentially interacted with septins of the SEPT6 group (p<0.001) aside from being the only septin group which interacted with members of its own group. Finally, septins of the SEPT3 group interacted preferentially with septins of the SEPT7 group (p<0.001). Furthermore, we found non-septin interactors which can be functionally attributed to a variety of different cellular activities, including: ubiquitin/sumoylation cycles, microtubular transport and motor activities, cell division and the cell cycle, cell motility, protein phosphorylation/signaling, endocytosis, and apoptosis.

• Binding, Competitive
• Carrier Proteins/genetics
• Carrier Proteins/metabolism
• Cell Cycle Proteins/genetics
• Cell Cycle Proteins/metabolism
• Cytoskeletal Proteins/genetics
• Cytoskeletal Proteins/metabolism
• Humans
• Multigene Family
• Protein Binding
• Septins/genetics
• Septins/metabolism
• Two-Hybrid System Techniques