Modulation of heat-shock protein 27 (Hsp27) anti-apoptotic activity by methylglyoxal modification.

Methylglyoxal (MG) is one of the side-products in glycolysis, and it reacts with proteins under physiological conditions. Here, we identified heat-shock protein 27 (Hsp27) as a major MG-modified protein in cells. MG modification of Hsp27 selectively occurs at Arg-188 to form argpyrimidine, and mutation in the residue represses the formation of a large oligomer. This modification process is essential to its repressing activity for cytochrome c-mediated caspase activation. Inhibition of MG modification of Hsp27 causes sensitization of the cells to anti-tumor drug-induced apoptosis. Thus, MG is a novel modulator of cell survival by directly incorporating with the specific protein residue.