Real‐time imaging of Hsp27‐cfp redistribution in response to oxidative stress

Abstract

The small heat shock protein, hsp27, has been suggested to regulate actin cytoskeleton structure and modulate the interaction of actin and myosin, given its biochemical properties and high expression levels in smooth muscle cells (SMCs) under stress. This may contribute to the mechanical plasticity of SMCs. It is proposed that hsp27's putative interaction with the actin cytoskeleton and its subcellular localization is regulated by its phosphorylation via the p38 MAP kinase pathway (MAPK). This pathway is activated by mechanical and oxidative stress, like hydrogen peroxide, and can be specifically inhibited with SB203580 (SB). We have established a real‐time oxidative stress smooth muscle cell imaging protocol utilizing time lapse microscopy to examine cellular redistribution of hsp27‐cfp in response to 200μM hydrogen peroxide +/‐ SB. Immunoanalysis of endogenous and ectopically expressed hsp27 demonstrates its phosphorylation and p38 activation. Interestingly, Hsp27‐cfp translocated to the perinuclear region with oxidative stress only with SB treatment. These results illustrate the dynamic and complex nature of hsp27 in the oxidative stress response of vascular smooth muscle cells.