Mechanical strain increases PDGF-B and PDGF beta receptor expression in vascular smooth muscle cells

Cyclic mechanical strain causes proliferation of vascular smooth muscle cells, mediated in part by platelet-derived growth factor (PDGF). We examined the effect of cyclic strain on expression of PDGF-B and the PDGF beta receptor. Neonatal rat vascular smooth muscle cells were exposed to 1 hertz cyclic strain on silicone elastomer plates. PDGF-B mRNA increased after 6 h of strain. In cells transfected with a PDGF-B promoter chloramphenicol acetyl transferase construct (psisCAT 6A), activity increased by 12-fold following 12 h of strain. Two neutralizing antibodies to the PDGF beta receptor both reduced strain-induced [(3)H]thymidine incorporation by 50%. Expression of the PDGF beta receptor protein increased 1.8-fold following 24 h of strain. During strain, PDGF beta receptor expression was not significantly altered by neutralizing antibodies to PDGF-B. Thus, both PDGF-B and the PDGF beta receptor are induced by cyclic mechanical strain and both contribute to cell proliferation in response to strain.