Stimulus-Specific Activation and Actin Dependency of Distinct, Spatially Separated ERK1-2 Fractions in A7r5 Smooth Muscle CellsReport as inadecuate




Stimulus-Specific Activation and Actin Dependency of Distinct, Spatially Separated ERK1-2 Fractions in A7r5 Smooth Muscle Cells - Download this document for free, or read online. Document in PDF available to download.

A proliferative response of smooth muscle cells to activation of extracellular signal regulated kinases 1 and 2 ERK1-2 has been linked to cardiovascular disease. In fully differentiated smooth muscle, however, ERK1-2 activation can also regulate contraction. Here, we use A7r5 smooth muscle cells, stimulated with 12-deoxyphorbol 13-isobutylate 20-acetate DPBA to induce cytoskeletal remodeling or fetal calf serum FCS to induce proliferation, to identify factors that determine the outcomes of ERK1-2 activation in smooth muscle. Knock down experiments, immunoprecipitation and proximity ligation assays show that the ERK1-2 scaffold caveolin-1 mediates ERK1-2 activation in response to DPBA, but not FCS, and that ERK1-2 is released from caveolin-1 upon DPBA, but not FCS, stimulation. Conversely, ERK1-2 associated with the actin cytoskeleton is significantly reduced after FCS, but not DPBA stimulation, as determined by Triton X fractionation. Furthermore, cytochalasin treatment inhibits DPBA, but not FCS-induced ERK1-2 phosphorylation, indicating that the actin cytoskeleton is not only a target but also is required for ERK1-2 activation. Our results show that 1 at least two ERK1-2 fractions are regulated separately by specific stimuli, and that 2 the association of ERK1-2 with the actin cytoskeleton regulates the outcome of ERK1-2 signaling.



Author: Susanne Vetterkind , Robert J. Saphirstein, Kathleen G. Morgan

Source: http://plos.srce.hr/



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