Optimal intensity shock wave promotes the adhesion and migration of rat osteoblasts via integrin β1-mediated expression of phosphorylated focal adhesion kinase.
To search for factors promoting bone fracture repair, we investigated the effects of extracorporeal shock wave (ESW) on the adhesion, spreading, and migration of osteoblasts and its specific underlying cellular mechanisms. After a single period of stimulation by 10 kV (500 impulses) of shock wave (SW), the adhesion rate was increased as compared with the vehicle control. The data from both wound healing and transwell tests confirmed an acceleration in the migration of osteoblasts by SW treatment. RT-PCR, flow cytometry, and Western blotting showed that SW rapidly increased the surface expression of α5 and β1 subunit integrins, indicating that integrin β1 acted as an early signal for ESW-induced osteoblast adhesion and migration. It has also been found that a significant elevation occurred in the expression of phosphorylated β-catenin and focal adhesion kinase (FAK) at the site of tyrosine 397 in response to SW stimulation after the increasing expression of the integrin β1 molecule. When siRNAs of integrin α5 and β1 subunit were added, the level of FAK phosphorylation elevated by SW declined. Interestingly, the adhesion and migration of osteoblasts were decreased when these siRNA reagents as well as the ERK1/2 signaling pathway inhibitors, U0126 and PD98059, were present. Further studies demonstrated that U0126 could inhibit the downstream integrin-dependent signaling pathways, such as the FAK signaling pathway, whereas it had no influence on the synthesis of integrin β1 molecule. In conclusion, these data suggest that ESW promotes the adhesion and migration of osteoblasts via integrin β1-mediated expression of phosphorylated FAK at the Tyr-397 site; in addition, ERK1/2 are also important for osteoblast adhesion, spreading, migration, and integrin expression.
Department of Orthopedics, First Affiliated Hospital, Shantou University Medical College, 57 Changping Road, Shantou, Guangdong 515041, China.
Jian-kun
JK
Xu
Hong-jiang
HJ
Chen
Xue-dong
XD
Li
Zhong-lian
ZL
Huang
Huan
H
Xu
Hai-long
HL
Yang
Jun
J
Hu
D000818:Animals; D002448:Cell Adhesion / Q000528:radiation effects*; D002465:Cell Movement / Q000528:radiation effects*; D002478:Cells, Cultured; D005260:Female; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D019220:High-Energy Shock Waves; D039482:Integrin alpha5 / Q000235:genetics / Q000378:metabolism; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D010006:Osteoblasts / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D010766:Phosphorylation; D061251:Primary Cell Culture; D011499:Protein Processing, Post-Translational / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012886:Skull / Q000166:cytology; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism
D039482:Integrin alpha5; D019012:Integrin beta1; D051176:beta Catenin; D051416:Focal Adhesion Protein-Tyrosine Kinases