Electrical Stimuli Release ATP to Increase GLUT4 Translocation and Glucose Uptake via PI3Kγ-Akt-AS160 in Skeletal Muscle Cells.
Skeletal muscle glucose uptake in response to exercise is preserved in insulin-resistant conditions, but the signals involved are debated. ATP is released from skeletal muscle by contractile activity and can autocrinely signal through purinergic receptors, and we hypothesized it may influence glucose uptake. Electrical stimulation, ATP, and insulin each increased fluorescent 2-NBD-Glucose (2-NBDG) uptake in primary myotubes, but only electrical stimulation and ATP-dependent 2-NBDG uptake were inhibited by adenosine-phosphate phosphatase and by purinergic receptor blockade (suramin). Electrical stimulation transiently elevated extracellular ATP and caused Akt phosphorylation that was additive to insulin and inhibited by suramin. Exogenous ATP transiently activated Akt and, inhibiting phosphatidylinositol 3-kinase (PI3K) or Akt as well as dominant-negative Akt mutant, reduced ATP-dependent 2-NBDG uptake and Akt phosphorylation. ATP-dependent 2-NBDG uptake was also inhibited by the G protein βγ subunit-interacting peptide βark-ct and by the phosphatidylinositol 3-kinase-γ (PI3Kγ) inhibitor AS605240. ATP caused translocation of GLUT4myc-eGFP to the cell surface, mechanistically mediated by increased exocytosis involving AS160/Rab8A reduced by dominant-negative Akt or PI3Kγ kinase-dead mutants, and potentiated by myristoylated PI3Kγ. ATP stimulated 2-NBDG uptake in normal and insulin-resistant adult muscle fibers, resembling the reported effect of exercise. Hence, the ATP-induced pathway may be tapped to bypass insulin resistance.
T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T20 T21 T22 T23 T24 T25 T26 T27 T28 T29 T2 T30 T31 T32 T33 T34 T35 T36 T37 T38 T39 T3 T40 T41 T42 T43 T44 T45 T46 T47 T48 T49 T4 T50 T51 T52 T53 T5 T6 T7 T8 T9
CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL GENE-N GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-N GENE-N CHEMICAL GENE-N GENE-Y GENE-Y GENE-N GENE-N GENE-N GENE-N GENE-N GENE-N GENE-N CHEMICAL GENE-Y GENE-Y GENE-N GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
2-NBD-Glucose 2-NBDG ATP 2-NBDG adenosine-phosphate suramin ATP suramin ATP ATP AS605240 2-NBDG ATP 2-NBDG ATP Glucose phosphatidylinositol 3-kinase-γ PI3Kγ GLUT4 AS160 Rab8A ATP Akt PI3Kγ kinase myristoylated PI3Kγ insulin insulin purinergic receptors insulin adenosine-phosphate phosphatase purinergic receptor ATP Akt insulin insulin Akt phosphatidylinositol 3-kinase PI3K Akt Akt Akt G protein βγ 2-NBDG GLUT4 PI3Kγ Akt AS160 ATP ATP glucose glucose ATP