ACTIVATION OF JNK SAPK AND ERK BY MECHANICAL STRAIN IN VASCULAR SMOOTH-MUSCLE CELLS DEPENDS ON EXTRACELLULAR-MATRIX COMPOSITION/

Application of cyclic mechanical strain to vascular smooth muscle (VSM ) cells elicits distinct cellular responses depending on extracellular matrix composition. We now examine activation of p42/p44 MAP kinase ( ERK) and c-jun amino terminal kinase (JNK/SAPK) by cyclic (1 Hz) mecha nical strain in neonatal rat VSM cells cultured on pronectin or lamini n. In cells grown on pronectin, mechanical strain activated both ERKs (peak 10-30 min) and JNK/SAPK (peak 15-30 min). On laminin, mechanical strain induced a comparable activation of JNK/SAPK to that seen on pr onectin, but no significant activation of ERKs. In contrast, applicati on of strain to adult VSM cells activated both enzymes independently o f extracellular matrix composition. In neonatal VSM cells, cyclic stra in induced SM-1 smooth muscle myosin in cells cultured on laminin, but not on pronectin, Thus in neonatal VSM cells, activation of ERKs and induction of SM-1 myosin by mechanical strain depend on extracellular matrix composition. (C) 1997 Academic Press.