Translocation of PKC isoforms in bovine aortic smooth muscle cells exposedto strain

Our laboratory has previously reported that the exposure of smooth muscle c ells (SMC) to the cyclic strain results in significant stimulation of prote in kinase C (PKC) activity by translocating the enzyme from the cytosol to the particulate fraction. We now sought to examine the strain-induced trans location of individual PKC isoforms in SMC. Confluent bovine aortic SMC gro wn on collagen type I-coated plates were exposed to cyclic strain for up to 100 s at average 10% strain with 60 cycles/min. Immunoblotting analysis de monstrates that SMC express PKC-alpha, -beta and -zeta in both cytosolic an d particulate fractions. Especially, PKC-alpha and -zeta were predominantly expressed in the cytosolic fraction. However, cyclic strain significantly (P < 0.05) increased PKC-<alpha> and -zeta in the particulate fraction and decreased in the cytosolic fraction. Thus, the cyclic strain-mediated stimu lation of PKC activity in SMC may be due to the translocation of PKC-alpha! and -zeta from the cytosolic to the particulate fraction. These results de monstrate that mechanical deformation causes rapid translocation of PKC iso forms, which may initiate a cascade of proliferation responses of SMC since NF-kappaB, which is involved in the cellular proliferation has been known to be activated by these PKC isoforms. (C) 2001 Wiley-Liss, Inc.