Alpha A-crystallin confers cellular thermoresistance.

The bovine eye lens protein alpha A-crystallin has been overexpressed both by stable transfection of HeLa cells and by transient transfection of NIH 3T3 cells. In both experimental systems alpha A-crystallin overexpression results in an increased cellular thermoresistance as judged by different clonal survival assays. In contrast, similar overexpression of another stable lens protein, beta B2-crystallin, does not confer thermoresistance. These results indicate that the structural relationship of alpha A-crystallin to the small heat shock proteins HSP25/27 and to alpha B-crystallin is sufficient for the shared thermoprotective function of all of these molecules and strongly suggests that the chaperone-like properties that they have in common are responsible for the conferred cellular thermoresistance.