title: Mechanical stimulation promote the osteogenic differentiation of bone marrow stromal cells through epigenetic regulation of Sonic Hedgehog.
abstract: Mechanical unloading leads to bone loss and disuse osteoporosis partly due to impaired osteoblastogenesis of bone marrow stromal cells (BMSCs). However, the underlying molecular mechanisms of this phenomenon are not fully understood. In this study, we demonstrated that cyclic mechanical stretch (CMS) promotes osteoblastogenesis of BMSCs both in vivo and in vitro. Besides, we found that Hedgehog (Hh) signaling pathway was activated in this process. Inhibition of which by either knockdown of Sonic hedgehog (Shh) or treating BMSCs with Hh inhibitors attenuated the osteogenic effect of CMS on BMSCs, suggesting that Hh signaling pathway acts as an endogenous mediator of mechanical stimuli on BMSCs. Furthermore, we demonstrated that Shh expression level was regulated by DNA methylation mechanism. Chromatin Immunoprecipitation (ChIP) assay showed that DNA methyltransferase 3b (Dnmt3b) binds to Shh gene promoter, leading to DNA hypermethylation in mechanical unloading BMSCs. However, mechanical stimulation down-regulates the protein level of Dnmt3b, results in DNA demethylation and Shh expression. More importantly, we found that inhibition of Dnmt3b partly rescued bone loss in HU mice by mechanical unloading. Our results demonstrate, for the first time, that mechanical stimulation regulates osteoblastic genes expression via direct regulation of Dnmt3b, and the therapeutic inhibition of Dnmt3b may be an efficient strategy for enhancing bone formation under mechanical unloading.
authors.affiliation: Department of Orthopedic Surgery, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.
authors.forename: Chuandong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Plastic & Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
authors.forename: Shengzhou
authors.initials: S
authors.lastname: Shan
authors.affiliation: Department of Orthopedic Surgery, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Plastic & Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of cell biology, Zunyi Medical College, Zunyi 563000, China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Li
authors.affiliation: The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Jiao Tong University School of Medicine (SJTUSM) & Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), Shanghai 200025, China.
authors.forename: Guoli
authors.initials: G
authors.lastname: Hu
authors.affiliation: The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Jiao Tong University School of Medicine (SJTUSM) & Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), Shanghai 200025, China.
authors.forename: Kerong
authors.initials: K
authors.lastname: Dai
authors.affiliation: Department of Plastic & Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Orthopedic Surgery, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China. Electronic address: xlzhangsjtu@163.com.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology* / Q000378:metabolism; D002478:Cells, Cultured; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D053823:Hedgehog Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis; D011485:Protein Binding; D013314:Stress, Mechanical; D000097584:DNA Methyltransferase 3B
chemical_list: D004248:DNA (Cytosine-5-)-Methyltransferases; D053823:Hedgehog Proteins; D000097584:DNA Methyltransferase 3B; C465570:Shh protein, mouse
keywords: BMSCs; DNA methylation; Hedgehog; Mechanical loading; Osteoblast differentiation