Abstract
Proliferation and migration of vascular smooth muscle cells (SMCs) are important processes involved in the pathogenesis of vascular disorders such as atherosclerosis and post‐angioplasty restenosis. Here we demonstrate that proliferation and migration of specific SMC subtypes is mitogen‐activated protein (MAP) kinase‐dependent. WKY12‐22 SMCs derived from the aortae of 12 day‐old pup rats proliferate and migrate faster than WKY3M‐22 SMCs derived from the aortae of adult rats. WKY12‐22 and WKY3M‐22 cells equally expressed the active forms of phospho (Thr^183^/Tyr^185^)‐c‐Jun N‐terminal kinase (JNK) and phospho (Tyr^182^)‐p38, whereas the activity of extracellular signal‐regulated kinase (ERK) was greater in WKY12‐22 cells compared with WKY3M‐22 cells. Proliferation of both SMC subtypes was attenuated by PD98059, SP600125 and SB202190, inhibitors of ERK, JNK, and p38, respectively. However, inhibition of PD98059 had a more profound effect on WKY12‐22 SMCs. Furthermore, migration of WKY12‐22 and WKY3M‐22 cells was inhibited by SP600125 and SB202190, however, PD98059 failed to influence migration of either SMC subtype. Hence, migration of both SMC subtypes is JNK‐ and p38‐dependent, but not ERK‐dependent. These findings demonstrate that SMC heterogeneity is mediated, at least in part, by the activity of specific MAP kinase subtypes. J. Cell. Biochem. 89: 289–300, 2003. © 2003 Wiley‐Liss, Inc.