CHARACTERIZATION OF PROTEINS ASSOCIATED WITH HEAT SHOCK PROTEIN HSP27 IN THE SQUAMOUS CELL CARCINOMA CELL LINE A431

Authors


To whom correspondence should be addressed: Ingela Kindas-Mügge, Institute of Tumorbiology/Cancer research, Borschkegasse 8a, A-1090 Vienna, Austria. Fax: 01 4277 9651. ingela-margaret.kindas-muegge@univie.ac.at

Abstract

Heat shock protein hsp27 is a molecular chaperone and identification of hsp27-binding proteins might help to elucidate its functional role in keratinocyte biology. In the present investigation we used a human epidermal cell carcinoma cell line (A431) transfected with hsp27 (A431/16) to study interference between hsp27 protein and other proteins. Immunoprecipitation experiments with anti-hsp27 antibody revealed a multicomponent complex when analysed by silver staining. By immunoblotting analysis we could demonstrate that hsp27 associates with actin, the mutant form of p53, hsp70 and hsp90. Immunofluorescence analysis showed a co-localization between hsp27 and p53, hsp70 and hsp90. To control for the specificity of the observed interactions, immuno-precipitations with antibodies to actin, p53, hsp70 and hsp90 respectively, were performed. All of the tested proteins demonstrated a coimmunoprecipitation with hsp27. We conclude that hsp27, like the other heat shock proteins, is part of a complex system of molecular chaperones in epidermal keratinocytes.

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