MUSCLE-SPECIFIC EXPRESSION OF DROSOPHILA HSP70 IN RESPONSE TO AGING AND OXIDATIVE STRESS

Induction of Drosophila hsp70 protein was detected during aging in fli ght muscle and leg muscle in the absence of heat shock, using an hsp70 -specific monoclonal antibody, and in transgenic flies containing hsp7 0-beta-galactosidase fusion protein reporter constructs. While hsp70 a nd reporter proteins were induced during aging, hsp70 message levels w ere not, indicating that aging-specific induction is primarily posttra nscriptional. In contrast, hsp22 and hsp23 were found to be induced du ring aging at the RNA level and with a broader tissue distribution. Th e same muscle-specific hsp70 reporter expression pattern was observed in young flies mutant for catalase (H2O2:H2O2 oxidoreductase, EC 1.11. 1.6). In catalase (cat) hypomorphic lines where flies survived to olde r ages, the time course of hsp70 reporter expression during aging was accelerated, and the initial and ultimate levels of expression were in creased. The hsp70 reporter was also induced in young flies mutant for copper/zinc superoxide dismutase (superoxide:superoxide oxidoreductas e, EC 1.15.1.1). Taken together, the results suggest that aging-specif ic hsp70 expression may be a result of oxidative damage.