Oestrogen receptors interact with the α-catalytic subunit of AMP-activated protein kinase.

Normal and pathological stressors engage the AMP-activated protein kinase (AMPK) signalling axis to protect the cell from energetic pressures. Sex steroid hormones also play a critical role in energy metabolism and significantly modify pathological progression of cardiac disease, diabetes/obesity and cancer. AMPK is targeted by 17 beta-oestradiol (E2), the main circulating oestrogen, but the mechanism by which E2 activates AMPK is currently unknown. Using an oestrogen receptor alpha/beta (ER alpha/beta) positive (T47D) breast cancer cell line, we validated E2-dependent activation of AMPK that was mediated through ER alpha (not ER beta) by using three experimental strategies. A series of co-immunoprecipitation experiments showed that both ERs associated with AMPK in cancer and striated (skeletal and cardiac) muscle cells. We further demonstrated direct binding of ERs to the alpha-catalytic subunit of AMPK within the beta gamma-subunit-binding domain. Finally, both ERs interacted with the upstream liver kinase B 1 (LKB1) kinase complex, which is required for E2-dependent activation of AMPK. We conclude that E2 activates AMPK through ER alpha by direct interaction with the beta gamma-binding domain of AMPK alpha.