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Downregulation of Protein Kinase C and Insulin Stimulated 2-Deoxyglucose uptake in Rat Adipocytes by Phorbol Esters, Glucose and Insulin.
Diabetes
  • T. Ishizuka
  • D. R. Cooper
  • Thomas Paul Arnold, Nova Southeastern University
  • H. Hermandez
  • R. V. Farese
ISBN or ISSN
0012-1797
Date of original Performance / Presentation
1-1-1992
Abstract

Phorbol esters translocatively activate and subsequently downregulate protein kinase C and insulin-stimulated glucose uptake in rat adipocytes. This study examined the possibility that other translocative activators of protein kinase C in rat adipocytes, e.g., insulin and glucose, provoke similar downregulating effects. Pretreatment of rat adipocytes for 20-24 h with phorbol esters, 3 nM insulin, 20 mM glucose, or 3 nM insulin plus 20 mM glucose resulted in concomitant decreases in protein kinase C and insulin-stimulated (or phorbol ester-stimulated) [3H]-2-deoxyglucose uptake. Downregulating effects of glucose on protein kinase C and insulin-stimulated [3H]-2-deoxyglucose uptake were also evident within 30 min in adipocytes freshly incubated in medium containing 5-20 mM, rather than 0, glucose. These findings confirm that protein kinase C is required during insulin-stimulated glucose uptake and raise the possibility that downregulation of protein kinase C by continued translocative activation of the enzyme may contribute (along with other factors) to impaired responsiveness of the glucose transport system after prolonged insulin and/or glucose treatment.

Citation Information
T. Ishizuka, D. R. Cooper, Thomas Paul Arnold, H. Hermandez, et al.. "Downregulation of Protein Kinase C and Insulin Stimulated 2-Deoxyglucose uptake in Rat Adipocytes by Phorbol Esters, Glucose and Insulin." Diabetes Vol. 40 p. 1274 - 1281
Available at: http://works.bepress.com/thomas-arnold/9/