Open AccessSonic Hedgehog Regulates Osteoblast Function by Focal Adhesion Kinase Signaling in the Process of Fracture Healing
Author(s) -
Yuu Horikiri,
Tsuyoshi Shimo,
Naito Kurio,
Tatsuo Okui,
K. Matsumoto,
Masahiro Iwamoto,
Akira Sasaki
Publication year - 2013
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0076785
Subject(s) - osteoclast , osteoblast , sonic hedgehog , microbiology and biotechnology , focal adhesion , bone healing , cellular differentiation , biology , chemistry , signal transduction , anatomy , in vitro , biochemistry , gene
Several biological studies have indicated that hedgehog signaling plays an important role in osteoblast proliferation and differentiation, and sonic hedgehog (SHH) expression is positively correlated with phosphorylated focal adhesion kinase (FAK) Tyr 397 . However, the relationship between them and their role in the process of normal fracture repair has not been clarified yet. Immunohistochemical analysis revealed that SHH and pFAK Tyr 397 were expressed in bone marrow cells and that pFAK Tyr 397 was also detected in ALP-positive osteoblasts near the TRAP-positive osteoclasts in the fracture site in the ribs of mice on day 5 after fracture. SHH and pFAK Tyr 397 were detectable in osteoblasts near the hypertrophic chondrocytes on day 14. In vitro analysis showed that SHH up-regulated the expression of FAK mRNA and pFAK Tyr 397 time dependently in osteoblastic MC3T3-E1 cells. Functional analysis revealed that 5 lentivirus encoding short hairpin FAK RNAs (shFAK)-infected MC3T3-E1 cell groups displayed a round morphology and decreased proliferation, adhesion, migration, and differentiation. SHH stimulated the proliferation and differentiation of MC3T3-E1 cells, but had no effect on the shFAK-infected cells. SHH also stimulated osteoclast formation in a co-culture system containing MC3T3-E1 and murine CD11b + bone marrow cells, but did not affect the shFAK-infected MC3T3-E1 co-culture group. These data suggest that SHH signaling was activated in osteoblasts at the dynamic remodeling site of a bone fracture and regulated their proliferation and differentiation, as well as osteoclast formation, via FAK signaling.