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Response to mechanical strain in an immortalized pre‐osteoblast cell is dependent on ERK1/2
Author(s) -
Fan Xian,
Rahnert Jill A.,
Murphy Tamara C.,
Nanes Mark S.,
Greenfield Edward M.,
Rubin Janet
Publication year - 2006
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20581
Subject(s) - stromal cell , osteoblast , rankl , microbiology and biotechnology , runx2 , cell culture , chemistry , signal transduction , activator (genetics) , biology , receptor , in vitro , cancer research , biochemistry , genetics
Mechanical strain inhibits osteoclastogenesis by regulating osteoblast functions: We have shown that strain inhibits receptor activator of NF‐κB ligand (RANKL) expression and increases endothelial nitric oxide synthase (eNOS) and nitric oxide levels through ERK1/2 signaling in primary bone stromal cells. The primary stromal culture system, while contributing greatly to understanding of how the microenvironment regulates bone remodeling is limited in use for biochemical assays and studies of other osteoprogenitor cell responses to mechanical strain: Stromal cells proliferate poorly and lose aspects of the strain response after a relatively short time in culture. In this study, we used the established mouse osteoblast cell line, c onditionally i mmortalized m urine c alvarial (CIMC‐4), harvested from mouse calvariae conditionally immortalized by insertion of the gene coding for a temperature‐sensitive mutant of SV40 large T antigen (TAg) and support osteoclastogenesis. Mechanical strain (0.5–2%, 10 cycles per min, equibiaxial) caused magnitude‐dependent decreases in RANKL expression to less than 50% those of unstrained cultures. Overnight strains of 2% also increased osterix (OSX) and RUNX2 expression by nearly twofold as measured by RT‐PCR. Importantly, the ERK1/2 inhibitor, PD98059, completely abrogated the strain effects bringing RANKL, OSX, and RUNX2 gene expression completely back to control levels. These data indicate that the strain effects on CIMC‐4 cells require activation of ERK1/2 pathway. Therefore, the CIMC‐4 cell line is a useful alternative in vitro model which effectively recapitulates aspects of the primary stromal cells and adds an extended capacity to study osteoblast control of bone remodeling in a mechanically active environment. J. Cell. Physiol. 207: 454–460, 2006. © 2006 Wiley‐Liss, Inc.