Endothelin stimulates glucose uptake and GLUT4 translocation via activation of endothelin ETA receptor in 3T3-L1 adipocytes

Endothelin-1 (ET-1) is a al-amino acid peptide that binds to G-protein-coup led receptors to evoke biological responses. This report studies the effect of ET-1 on regulating glucose transport in 3T3-L1 adipocytes. ET-1, but no t angiotensin II, stimulated glucose uptake in a dose-dependent manner with an EC50 value of 0.29 nM and a 2.47-fold stimulation at 100 nM. ET-1 stimu lated glucose uptake in differentiated 3T3-L1 cells but had no effect in un differentiated cells, although ET-1 stimulated phosphatidylinositol hydroly sis to a similar degree in both. The 3T3-L1 cells expressed similar to 560, 000 sites/cell of ETA receptor, which was not altered during differentiatio n. Western blot analysis and immunofluorescence staining show that ET-1 sti mulated the translocation of insulin-responsive aminopeptidase and GLUT4 to the plasma membrane, The effect of ET-I on glucose uptake was blocked by A -216546, an antagonist selective for the ETA receptor. ET-1 treatment did n ot induce phosphorylation of insulin receptor beta-subunit, insulin recepto r substrate-1, or Akt but stimulated the tyrosyl phosphorylation of a 75-kD a protein. Genistein (100 mu M), an inhibitor of tyrosine kinases, inhibite d ET-1-stimulated glucose uptake. Our results show that ET-1 stimulates GLU T4 translocation and glucose uptake in 3T3-L1 adipocytes via activation of ETA receptor.