alpha-Glycerophosphate shuttle in a clonal beta-cell line.
It has been proposed that the alpha-glycerophosphate (alpha-GOP) shuttle plays a crucial role in regulation of glycolysis in beta-cells by linking reoxidation of cytosolic NADH to formation of ATP in the electron transport chain (J. Biol. Chem. 265: 8287, 1981). Direct evidence for this suggestion is still lacking, however. In this work the operation of the alpha-GOP shuttle was investigated in the insulin-secreting cell line HIT-T15. The constituent enzymes of the pathway were found to be present in HIT cells. Flavin-linked alpha-GOP dehydrogenase was associated with the mitochondrial fraction, whereas NAD+-dependent alpha-GOP dehydrogenase was localized in the cytosol. In the presence of amobarbital (used to preserve the function of the alpha-GOP shuttle under conditions where oxidation of NADH by the respiratory chain was blocked), glucose increased insulin secretion, O2 consumption, and the cell [ATP]/[ADP] when compared with amobarbital alone. These results indicate that the alpha-GOP shuttle contributes to ATP generation in HIT cells and that its activation may be necessary for the initiation of insulin secretion by glucose.
Meglasson
M D
MD
Diabetes Research Center, University of Pennsylvania School of Medicine, Philadelphia 19104.
Smith
K M
KM
Nelson
D
D
Erecinska
M
M
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000654:Amobarbital / Q000494:pharmacology; D002460:Cell Line; D002999:Clone Cells; D003600:Cytosol / Q000378:metabolism; D004579:Electron Transport; D005947:Glucose / Q000494:pharmacology; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D006019:Glycolysis / Q000187:drug effects; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid
D005994:Glycerophosphates; D007328:Insulin; D007773:Lactates; D011773:Pyruvates; D009243:NAD; D006153:Guanosine Diphosphate; D019344:Lactic Acid; D000244:Adenosine Diphosphate; D019289:Pyruvic Acid; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; C029620:alpha-glycerophosphoric acid; D005993:Glycerolphosphate Dehydrogenase; D000654:Amobarbital; D005947:Glucose