(T431) HEAT STRESS INDUCES AMPK ACTIVATION AND MEIOTIC MATURATION IN MOUSE OOCYTES.
LaRosa, Cean1, Downs, Stephen1, 1 Marquette University, Milwaukee, WI
ABSTRACT- AMP-activated protein kinase (AMPK), a stress response enzyme, has recently been implicated in the regulation of meiotic resumption in mouse oocytes. AICAR, a common pharmacological activator of AMPK, triggers meiotic resumption in arrested mouse oocytes in vitro. We have previously shown that a variety of cellular stresses are able to induce germinal vesicle breakdown (GVB), and the present study focuses on oocytes exposed to a brief heat shock. Our experiments reveal that 1) a 60 minute pulse of oocytes at 42C optimally triggers GVB; 2) the heat-treated increase in maturation is dose-dependently blocked by compound C, an inhibitor of AMPK; 3) heat-treated denuded oocytes (DO) and cumulus-enclosed oocytes (CEO) exhibit increased AMPK activity prior to GVB that is blocked by compound C; and 4) heat-induced meiotic resumption occurs in the presence of three different meiotic inhibitors (dbcAMP, hypoxanthine, and isobutylmethylxanthine). Also, we have been unable to detect changes in other stress-activated protein kinases, such as p38 and JNK MAPK, as well as ERK1/2, in association with heat-induced or AICAR-induced maturation. Furthermore, DO and CEO subjected to heat stress progress meiotically to metaphase II and extrude a polar body, indicating the stress is not damaging the meiotic spindle or the ability of the oocyte to complete maturation. Taken together, these data suggest a short exposure to heat stress is sufficient to trigger AMPK activation and meiotic induction in mouse oocytes. Heat-induced maturation occurs under a variety of inhibitory conditions through the activation of AMPK and not kinases from the MAPK family. Supported by funds from the NIH (HD040392).
KEY WORDS: meiotic maturation, stress, AMPK