Alphavbeta3-integrin antagonists inhibit thrombin-induced proliferation and focal adhesion formation in smooth muscle cells.
Alphavbeta3-integrin antagonists reduced neointimal formation following vascular injury in eight different animal models. Because alpha-thrombin contributes to neointimal formation, we examined the hypothesis that alphavbeta3-integrins influence alpha-thrombin-induced signaling. Cultured rat aortic smooth muscle cells (RASMC) expressed alphavbeta3-integrins as demonstrated by immunofluorescence microscopy and fluorescence-activated cell sorting analysis. Proliferative responses to alpha-thrombin were partially inhibited by anti-beta3-integrin monoclonal antibody F11 and by cyclic RGD peptides. Immunofluorescence microscopy showed that alpha-thrombin stimulated a rapid increase in the formation of focal adhesions as identified by vinculin staining and that this effect was partially inhibited by alphavbeta3 antagonists. Beta3-integrin staining was diffuse in quiescent RASMC and did not concentrate at sites of focal adhesions following thrombin treatment. Alpha-thrombin elicited a time-dependent increase in activation of c-Jun NH2-terminal kinase-1 (JNK1) and in tyrosine phosphorylation of focal adhesion kinase (FAK). Alphavbeta3-integrin antagonists partially inhibited increases in JNK1 activity but had no effect on FAK phosphorylation. In SMC isolated from beta3-integrin-deficient mice, focal adhesion formation was impaired in response to thrombin but not sphingosine-1-phosphate, a potent activator of Rho. In summary, alphavbeta3-integrins play an important role in alpha-thrombin-induced proliferation and focal adhesion formation in RASMC.
Sajid
M
M
Division of Cardiology, Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, NC 27599-7075, USA.
Zhao
R
R
Pathak
A
A
Smyth
S S
SS
Stouffer
G A
GA
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D022001:Focal Adhesions / Q000187:drug effects* / Q000502:physiology; D039302:Integrin alphaVbeta3 / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D039302:Integrin alphaVbeta3; D013917:Thrombin