title: Simvastatin enhances Rho/actin/cell rigidity pathway contributing to mesenchymal stem cells' osteogenic differentiation.
abstract: Recent studies have indicated that statins induce osteogenic differentiation both in vitro and in vivo. The molecular mechanism of statin-stimulated osteogenesis is unknown. Activation of RhoA signaling increases cytoskeletal tension, which plays a crucial role in the osteogenic differentiation of mesenchymal stem cells. We thus hypothesized that RhoA signaling is involved in simvastatin-induced osteogenesis in bone marrow mesenchymal stem cells. We found that although treatment with simvastatin shifts localization of RhoA protein from the membrane to the cytosol, the treatment still activates RhoA dose-dependently because it reduces the association with RhoGDIα. Simvastatin also increased the expression of osteogenic proteins, density of actin filament, the number of focal adhesions, and cellular tension. Furthermore, disrupting actin cytoskeleton or decreasing cell rigidity by using chemical agents reduced simvastatin-induced osteogenic differentiation. In vivo study also confirms that density of actin filament is increased in simvastatin-induced ectopic bone formation. Our study is the first to demonstrate that maintaining intact actin cytoskeletons and enhancing cell rigidity are crucial in simvastatin-induced osteogenesis. The results suggested that simvastatin, which is an osteoinductive factor and acts by increasing actin filament organization and cell rigidity combined with osteoconductive biomaterials, may benefit stem-cell-based bone regeneration.
authors.affiliation: Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: I-Chun
authors.initials: IC
authors.lastname: Tai
authors.affiliation: Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Yao-Hsien
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Department of Orthopedics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Chung-Hwan
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Shu-Chun
authors.initials: SC
authors.lastname: Chuang
authors.affiliation: Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Department of Orthopedics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan ; Department of Orthopedics, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
authors.forename: Je-Ken
authors.initials: JK
authors.lastname: Chang
authors.affiliation: Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Department of Physiology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Orthopaedic Research Center, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan ; Department of Marine Biotechnology and Resources, National Sun Yat-sen UniVersity, Kaohsiung, Taiwan.
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Ho
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D010012:Osteogenesis / Q000187:drug effects*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D019821:Simvastatin / Q000008:administration & dosage / Q000494:pharmacology*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D019821:Simvastatin; D000469:Alkaline Phosphatase; D020742:rhoA GTP-Binding Protein
keywords: BMSCs; RhoA; cytoskeleton; osteogenic differentiation; statins