• IE180
• PRV infection
• glucocorticoid
• neuron-like cells
• productive infection

• Herpesvirus 1, Suid/drug effects
• Herpesvirus 1, Suid/physiology
• Animals
• Epithelial Cells/virology
• Epithelial Cells/drug effects
• Neurons/virology
• Neurons/drug effects
• Swine
• Receptors, Glucocorticoid/metabolism
• Receptors, Glucocorticoid/genetics
• Dexamethasone/pharmacology
• Pseudorabies/virology
• Glucocorticoids/pharmacology
• Virus Replication/drug effects
• Virus Activation/drug effects
• Cell Line
• Promoter Regions, Genetic

• 32172823 MOST | National Natural Science Foundation of China (NSFC)

• Benzophenones
• Animals
• Polymers/chemistry
• Polyethylene Glycols/chemistry
• Ketones/chemistry
• Ketones/pharmacology
• Osseointegration/drug effects
• Rats
• Mesenchymal Stem Cells/drug effects
• RNA, Small Interfering/genetics
• Surface Properties
• Osteogenesis/drug effects
• Anti-Bacterial Agents/pharmacology
• Prostheses and Implants
• Male
• Rats, Sprague-Dawley
• Cell Differentiation/drug effects
• Femur
• Tannins/chemistry
• Tannins/pharmacology
• Biocompatible Materials/chemistry
• Coated Materials, Biocompatible/chemistry
• Coated Materials, Biocompatible/pharmacology

• Natural Science Foundation of Tianjin Municipality

• RNA, Small Interfering/chemistry
• RNA, Small Interfering/pharmacology
• Animals
• Rats
• Bone Regeneration/drug effects
• Osteogenesis/drug effects
• Humans
• RNAi Therapeutics
• Rats, Sprague-Dawley
• Nucleic Acids/chemistry
• Drug Delivery Systems
• Cell Differentiation/drug effects
• RNA Interference
• Male

• E3 ubiquitin ligase
• Smad ubiquitination regulator 1
• bone homeostasis
• bone morphogenesis protein signaling
• cancer
• nerve cell development

• Bone metabolism
• Glucocorticoid-induced osteoporosis
• Metabolomics
• Taurine and hypotaurine metabolism
• Yi-Guan-Jian decoction

• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China
• 2018FE001 (-087) The Provincial Basic Research Program of Science and Technology Department of Yunnan Province, China

• estrogen
• glucocortcoid
• osteoporosis

• Bone Remodeling/drug effects
• Bone Resorption/metabolism
• Cell Differentiation/drug effects
• Estrogens/deficiency
• Estrogens/metabolism
• Female
• Glucocorticoids/pharmacology
• Humans
• Osteoblasts/metabolism
• Osteoclasts/metabolism
• Osteocytes/metabolism
• Osteogenesis/drug effects
• Osteoporosis/etiology
• Osteoporosis/metabolism
• Postmenopause/physiology
• RANK Ligand/metabolism
• Tumor Necrosis Factor-alpha/metabolism

• TCRD-TPE-110-06 Taipei Tzu Chi Hospital

Osteoporosis is a systemic bone disease characterized by decreased bone mass and deterioration of bone microstructure, which leads to increased bone fragility and increased risk of fractures. Casein kinase 2 interacting protein 1 (CKIP-1, also known as PLEKHO1) is involved in the biological process of bone formation, differentiation and apoptosis, and is a negative regulator of bone formation. QiangGuYin (QGY) is a famous TCM formula that has been widely used in China for the clinical treatment of postmenopausal osteoporosis for decades, but the effect in regulating CKIP-1 on osteoporosis is not fully understood. This study aimed to explore the potential mechanism of CKIP-1 participating in autophagy in bone cells through the AKT/mTOR signaling pathway and the regulatory effect of QGY. The results in vivo showed that QGY treatment can significantly improve the bone quality of osteoporotic rats, down-regulate the expression of CKIP-1, LC3II/I and RANKL, and up-regulated the expression of p62, p-AKT/AKT, p-mTOR/mTOR, RUNX2 and OPG. It is worth noting that the results in vitro confirmed that CKIP-1 interacts with AKT. By up-regulating the expression of Atg5 and down-regulating the p62, the level of LC3 (autophagosome) is increased, and the cells osteogenesis and differentiation are inhibited. QGY inhibits the combination of CKIP-1 and AKT in osteoblasts, activates the AKT/mTOR signaling pathway, inhibits autophagy, and promotes cell differentiation, thereby exerting an anti-osteoporosis effect. Therefore, QGY targeting CKIP-1 to regulate the AKT/mTOR-autophagy signaling pathway may represent a promising drug candidate for the treatment of osteoporosis.

• AKT/mTOR signaling pathway
• CKIP-1
• QiangGuYin
• apoptosis
• osteoporosis

The ubiquitin–proteasome system (UPS) is an essential pathway that regulates the homeostasis and function of intracellular proteins and is a crucial protein-degradation system in osteoblast differentiation and bone formation. Abnormal regulation of ubiquitination leads to osteoblast differentiation disorders, interfering with bone formation and ultimately leading to osteoporosis. E3 ubiquitin ligases (E3) promote addition of a ubiquitin moiety to substrate proteins, specifically recognizing the substrate and modulating tyrosine kinase receptors, signaling proteins, and transcription factors involved in the regulation of osteoblast proliferation, differentiation, survival, and bone formation. In this review, we summarize current progress in the understanding of the function and regulatory effects of E3 ligases on the transcription factors and signaling pathways that regulate osteoblast differentiation and bone formation. A deep understanding of E3 ligase-mediated regulation of osteoblast differentiation provides a scientific rationale for the discovery and development of novel E3-targeting therapeutic strategies for osteoporosis.

• E3 ubiquitin ligase
• bone formation
• osteoblast differentiation
• signaling pathway
• therapeutic target
• transcription factor

• osteoporosis
• stem cells
• targeted therapy

Xenograft bone scaffolds have advantages such as mechanical strength, sufficient source and safety. Combined with siRNA properly targeting CKIP-1, a negative regulator of osteogenesis, may contribute to the repair result of calcine bone alone.

Herein, we constructed a novel xenograft bovine bone scaffold namely (DSS)6-liposome/CKIP-1 siRNA/calcine bone, the characteristics of which were investigated by confirming the effect of (DSS)6-liposome, observing the appearance and testing mechanical strength of calcine bone, and observing the combined result of CKIP-1 siRNA by FAM immunofluorescence. In addition, cytotoxicity by CCK-8 and LDH activity of L929 ​cells and MC3T3-E1 osteoblasts cultured with the scaffold were tested in vitro, primary osteoblasts proliferation, the mRNA expressions of CKIP-1, ALP, COL1-α and OCN, the protein expressions of CKIP-1, BMP-2, COL-1 and Runx2 and calcium nodules were also determined by CCK-8, RT-qPCR, western-blot and Alizarin Red staining in vitro. Then, we successively established the skull defect model for evaluating the repair result of the novel scaffold by HE staining of 2, 4, 8 and 12 weeks, immumohistochemical stainings of 2, 4, 8 and 12 weeks such as ALP, COL-1α and OCN, Mirco-CT scanning of 4 and 12 weeks and the relative parameters and so on in vivo.

It indicated that (DSS)6-liposome/CKIP-1 siRNA/calcine bone could successfully knock down the CKIP-1 mRNA and protein expressions, promote osteoblasts proliferation with the little cytotoxicity in vitro, increase the protein expressions of BMP-2, COL-1 and Runx2 in vitro, increase mRNA expressions of ALP, COL-1α and OCN in vitro and in vivo, and have a better bone defect repair effect with few side effects in rats after 12 weeks.

Our research indicates (DSS)6-liposome/CKIP-1 siRNA/calcine bone could repair skull defects well in rats, and it may lay the foundation of applicating the novel xenograft bone scaffold in the clinical.

These findings provide evidence that (DSS)6- liposome/CKIP-1 siRNA/calcine bone could be used as a novel xenograft bone scaffold for osteogenesis with the good safety.

• Bone defect
• True bone calcine
• Xenograft bone scaffolds
• casein kinase 2 interacting protein-1
• siRNA

Rationale: The migration of mesenchymal osteoprogenitor cells (OPCs) to bone formation surface is the initial step of osteoblastogenesis before they undergo osteoblast differentiation and maturation for governing bone formation. However, whether the migration capacity of OPCs is compromised during aging and how it contributes to the aging-related bone formation reduction remain unexplored. In the present study, we identified a migration inhibitory factor (i.e., long noncoding RNA PMIF) and examined whether targeting lnc-PMIF could facilitate osteoprogenitor cells migrating to bone formation surface to promote bone formation during aging.

Methods: Primary OPCs from young (6-momth-old) and aged (18-momth-old) C57BL/6 mice and stable lnc-PMIF knockdown/overexpression cell lines were used for in vitro and in vivo cell migration assay (i.e., wound healing assay, transwell assay and cell intratibial injection assay). RNA pulldown-MS/WB and RIP-qPCR were performed to identify the RNA binding proteins (RBPs) of lnc-PMIF. Truncations of lnc-PMIF and the identified RBP were engaged to determine the interaction motif between them by RNA pulldown-WB and EMSA. By cell-based therapy approach and by pharmacological approach, small interfering RNA (siRNA)-mediated lnc-PMIF knockdown were used in aged mice. The cell migration ability was evaluated by transwell assay and cell intratibial injection assay. The bone formation was evaluated by microCT analysis and bone morphometry analysis.

Results: We reported that the decreased bone formation was accompanied by the reduced migration capacity of the bone marrow mesenchymal stem cells (BMSCs, the unique source of OPCs in bone marrow) in aged mice. We further identified that the long non-coding RNA PMIF (postulated migration inhibitory factor) (i.e., lnc-PMIF) was highly expressed in BMSCs from aged mice and responsible for the reduced migration capacity of aged OPCs to bone formation surface. Mechanistically, we found that lnc-PMIF could bind to human antigen R (HuR) for interrupting the HuR-β-actin mRNA interaction, therefore inhibit the expression of β-actin for suppressing the migration of aged OPCs. We also authenticated a functionally conserved human lncRNA ortholog of the murine lnc-PMIF. By cell-based therapy approach, we demonstrated that replenishing the aged BMSCs with small interfering RNA (siRNA)-mediated lnc-PMIF knockdown could promote bone formation in aged mice. By pharmacological approach, we showed that targeted delivery of lnc-PMIF siRNA approaching the OPCs around the bone formation surface could also promote bone formation in aged mice.

Conclusion: Toward translational medicine, this study hints that targeting lnc-PMIF to facilitate aged OPCs migrating to bone formation surface could be a brand-new anabolic strategy for aging-related osteoporosis.

• aging
• bone formation
• cell migration
• long non-coding RNA
• osteoprogenitor cells

• BMSC
• CKIP-1
• Fracture healing
• Let-7i-5p
• Osteogenesis differentiation

• RNA aptamer
• Wnt-5a
• agomirs
• antagomirs
• bone marrow mesenchymal stem cells (BMSCs)
• osteogenesis

There are less scar formations in some wounds after wound repair. Our earlier study had shown that the amount of collagen fibers in canine prostatic urethra wound were less than in bladder neck wound after 2-μm laser resection of the prostate (TmLRP) and partial bladder neck mucosa at 4 weeks. The purpose of this study was to observe the amount of scar tissue and characterize the probable causes of “less scar healing” in prostatic urethra wound.

A total of 12 healthy adult male crossbred canines underwent resection of prostate and partial bladder neck mucosa using 2-μm laser. The prostatic urethra and bladder neck wound specimens were harvested at 3, 4, 8 and 12 weeks after operation, respectively. The histopathologic characteristics were observed by hematoxylin and eosin(HE)staining, and the expression of transforming growth factor-β₁ (TGF-β₁) and casein kinase-2 interacting protein-1 (CKIP-1) were examined by immunohistochemistry in prostatic urethra and bladder neck wound, respectively. Overexpressed CKIP-1 human prostate epithelial cells (BPH-1 cells) were established and the expression of TGF-β₁ was detected by Western blotting. Furthermore, a non-contact co-culture system of BPH-1 cells and human fibroblast (HFF-1) cells was used to observe the effects of BPH-1 cell and their high CKIP-1 levels on the expression of TGF-β₁ in HFF-1 in vitro.

The histology showed that there were a large number of prostatic epithelium and a small amount of scar tissue in prostatic urethra wound, while no epithelial cells and more scar tissue in bladder neck wound at 4, 8 and 12 weeks after repair. There were a higher expression level of TGF-β₁ in prostate epithelial cells and fibroblasts and a lower expression level of CKIP-1 in prostate epithelial cells at 3 weeks after surgery in prostatic urethral wound. Compared to week 3, the TGF-β₁ expression decreased both in prostate epithelial cells and fibroblasts at 4, 8 and 12 weeks in prostatic urethral wound (p < 0.05 or p < 0.01). The CKIP-1 expression increased in prostate epithelial cells at 4, 8 and 12 weeks compared to 3 weeks in prostatic urethra wound (p < 0.01). A higher TGF-β1 expression level of fibroblasts was observed in bladder neck wound at 3 weeks. And there was no significant change in the expression of TGF-β₁ of fibroblasts in 3, 4, 8 and 12 weeks after operation in bladder neck wound. Both the prostate urethra and bladder neck wound fibroblasts showed weak expression of CKIP-1 and there was no significant change in 3, 4, 8 and 12 weeks. The vitro experiments showed that the TGF-β₁ expression in BPH-1 cells with CKIP-1 overexpression decreased 25% compared with control group (p < 0.05). Furthermore, the expression of TGF-β₁ in HFF-1 cells of co-cultured group decreased by 20% compared with Control group (p < 0.05); the expression of TGF-β₁ in HFF-1 cells of overexpression co-culture group were reduced by 15% compared with co-cultured group (p < 0.01).

A large number of prostate epithelial cells in prostatic urethra wound may be one of the causes of less formation of scar tissue after repair. The prostate epithelial cells might reduce expression level of TGF-β₁ by raising CKIP-1 expression and inhibit expression of TGF-β₁ in peripheral fibroblasts at remodeling stage to reduce the excessive proliferation of fibrous cells and the excessive scar formation.

• CKIP-1
• Less scar
• Prostatic urethra wound
• TGF-β1
• Wound healing

• Biological processes
• CKIP-1
• Intrinsic mechanisms
• Molecular functions
• Therapeutic strategies

• Animals
• Bone Morphogenetic Protein 4/metabolism
• Cell Line
• Chick Embryo
• Chickens
• Gastrulation/physiology
• Intracellular Signaling Peptides and Proteins/genetics
• Intracellular Signaling Peptides and Proteins/metabolism
• Neural Crest/embryology
• Neural Plate/embryology
• Neural Plate/metabolism
• Neurulation/physiology
• Ubiquitin-Protein Ligases/metabolism
• Wnt Signaling Pathway/physiology

• F32 HD088022 NICHD NIH HHS
• P01 HD037105 NICHD NIH HHS
• R01 DE024157 NIDCR NIH HHS

Osteoporosis is a systemic skeletal disorder characterized by reduced bone mass and deterioration of bone microarchitecture, which results in increased bone fragility and fracture risk. Casein kinase 2-interacting protein-1 (CKIP-1) is a protein that plays an important role in regulation of bone formation. The effect of CKIP-1 on bone formation is mainly mediated through negative regulation of the bone morphogenetic protein pathway. In addition, CKIP-1 has an important role in the progression of osteoporosis. This review provides a summary of the recent studies on the role of CKIP-1 in osteoporosis development and treatment.

Cite this article: X. Peng, X. Wu, J. Zhang, G. Zhang, G. Li, X. Pan. The role of CKIP-1 in osteoporosis development and treatment. Bone Joint Res 2018;7:173–178. DOI: 10.1302/2046-3758.72.BJR-2017-0172.R1.

• BMP pathway
• Bone formation
• CKIP-1
• Osteoporosis

• CKIP-1
• Gastric cancer
• invasion
• migration
• proliferation
• wound healing