Cytoskeletal signaling by way of α-actinin-1 mediates ERKI/2 activation by repetitive deformation in human Caco2 intestinal epithelial cells

Background: Repetitive deformation stimulates proliferation in human Caco2 intestinal epithelial cells by way of an ERKI/2-dependent pathway. We examined the effects of cytoskeletal perturbation on deformation-induced signaling in Caco2 cells. Methods: The Caco2 cell cytoskeleton was disrupted with either cytochalasin D, phalloidin, colchicine, or paclitaxel. Levels of alpha-actinin-1 and -4 and paxillin were reduced by specific small interfering RNA. Cells on collagen I-precoated membranes were subjected to 10% repetitive deformation at 10 cycles/min. After I hour, cells were lysed for Western blot analysis. Results: Strain-activated ERK1/2, focal adhesion kinase, and Src phosphorylation in dimethyl sulfoxideand/or nontargeting small interfering RNA-treated control cell populations. Cytochalasin D and paclitaxel, but not phalloidin and colchicine, blocked ERK 1/2 phosphorylation. A decrease in a-actinin-1, but not in alpha-actinin-4 or paxillin, inhibited ERKI/2 and focal adhesion kinase phosphorylation, whereas Src activation appears to be independent of these effects. Conclusions: The intestinal epithelial cell cytoskeleton may transduce mechanical signals by way of alpha-actinin-1 into the focal adhesion complex, culminating in ERKI/2 activation and proliferation. (C) 2007 Excerpta Medica Inc. All rights reserved.