Induction of phospho-Thr-172 AMPK in 3T3-L1 adipocytes exposed to cold or treated with anisomycin, mithramycin A, and ionic compounds.

Cold exposure induces cellular responses, including subcellular molecule expression and transport responses, similar to those stimulated by insulin in 3T3-L1 (L1) adipocytes. The transport response is induced in L1 adipocytes treated with translation inhibitors. We examined the level of phospho-Thr-172 AMPK (an active form of AMPK, a known energy-state sensor) in L1 adipocytes exposed to different temperatures of 4-37 degrees C or stressors, including chemical inhibitors and activators. The phospho-AMPK level increased in cold-exposed cells and their subcellular fractions and decreased after rewarming and serum depletion. The phospho-molecule was also induced by anisomycin, which induces protein kinase activation and translation inhibition; mithramycin A, an inhibitor of transcription factor binding; and ionic compounds, which stimulate molecular signaling and alter several gene expression. These results indicate that temperature responses are mimicked by metabolic stressors through phospho-molecule alteration. Our results provide possible clues for clarifying the mechanisms underlying cold responses in L1 adipocytes.