title: Regulation of PTHrP expression by cyclic mechanical strain in postnatal growth plate chondrocytes.
abstract: Mechanical loading has been widely considered to be a crucial regulatory factor for growth plate development, but the exact mechanisms of this regulation are still not completely understood. In the growth plate, parathyroid hormone-related protein (PTHrP) regulates chondrocyte differentiation and longitudinal growth. Cyclic mechanical strain has been demonstrated to influence growth plate chondrocyte differentiation and metabolism, whereas the relationship between cyclic mechanical strain and PTHrP expression is not clear. The objective of this study was to investigate whether short-term cyclic tensile strain regulates PTHrP expression in postnatal growth plate chondrocytes in vitro and to explore whether the organization of cytoskeletal F-actin microfilaments is involved in this process. To this end, we obtained growth plate chondrocytes from 2-week-old Sprague-Dawley rats and sorted prehypertrophic and hypertrophic chondrocytes using immunomagnetic beads coated with anti-CD200 antibody. The sorted chondrocytes were subjected to cyclic tensile strain of varying magnitude and duration at a frequency of 0.5 Hz. We found that cyclic strain regulates PTHrP expression in a magnitude- and time-dependent manner. Incubation of chondrocytes with cytochalasin D, an actin microfilament-disrupting reagent, blocked the induction of PTHrP expression in response to strain. The results suggest that short-term cyclic tensile strain induces PTHrP expression in postnatal growth plate prehypertrophic and hypertrophic chondrocytes and that PTHrP expression by these chondrocytes may subsequently affect growth plate development. The results also support the idea that the organization of cytoskeletal F-actin microfilaments plays an important role in mechanotransduction.
authors.affiliation: Department of Rehabilitation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Kaixiang
authors.initials: K
authors.lastname: Yang
authors.forename: Hongbo
authors.initials: H
authors.lastname: You
authors.forename: Anmin
authors.initials: A
authors.lastname: Chen
authors.forename: Jiang
authors.initials: J
authors.lastname: Wang
authors.forename: Kai
authors.initials: K
authors.lastname: Xu
authors.forename: Chen
authors.initials: C
authors.lastname: Gong
authors.forename: Jingfan
authors.initials: J
authors.lastname: Shao
authors.forename: Zhongxi
authors.initials: Z
authors.lastname: Ma
authors.forename: Fengjing
authors.initials: F
authors.lastname: Guo
authors.forename: Jun
authors.initials: J
authors.lastname: Qi
mesh_terms: D000818:Animals; D019902:Chondrocytes / Q000378:metabolism*; D006132:Growth Plate / Q000166:cytology*; D040542:Mechanotransduction, Cellular / Q000502:physiology; D044162:Parathyroid Hormone-Related Protein / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013718:Tensile Strength / Q000502:physiology
chemical_list: D044162:Parathyroid Hormone-Related Protein
keywords: Chondrocyte; F-actin; Growth plate; Mechanical strain; Mechanotransduction; Parathyroid hormone-related protein (PTHrP)