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- Title
Differential Effect of PKC Isoform on Insulin- and Phorbol Ester-Stimulated Glucose Uptake Mechanism in Rat Adipocytes.
- Authors
Ishizuka, Tatsuo; Miura, Atsushi; Kajita, Kazuo; Ishizawa, Masayoshi; Kimura, Mika; Huang, Yannan; Kawai, Yasunori; Morita, Hiroyuki; Uno, Yoshihiro; Yasuda, Keigo
- Abstract
Insulin stimulates glucose uptake in association with phosphatidylinositol (PI) 3-kinase activation mechanisms in rat adipocytes. Insulin stimulated glucose uptake to 6.5-fold, and 12-o-tetradecanoyl phorbol 13-acetate (TPA) also stimulated glucose uptake to 4.5-fold in rat adipocytes. We examined these differences in glucose uptake, PKCζ activation, and PI 3-kinase activation after stimulation with insulin and TPA. TPA stimulated PI 3-kinase activity and increased the p85 subunit of PI 3-kinase immunoreactivity in anti-phosphotyrosine antibody-immunoprecipitated protein. Insulin and TPA provoked increases in membrane PKC ζ immunoreactivity.The PI 3-kinase inhibitor,wortmannin, suppressed insulin-induced increases in glucose uptake, PI 3-kinase activity, and PKCζ activation. Wortmannin also suppressed TPA-induced PI 3-kinase activity and PKCζ activation but suppressed TPA-induced glucose uptake to only a small extent. The PKC inhibitor, Go6976, which only inhibits conventional PKCα and _, suppressed TPA-induced glucose uptake, but suppressed insulin-induced glucose uptake to only a small extent. On the other hand, the PKC inhibitor, RO32-0432, which inhibits conventional, novel, and atypical PKCs, markedly suppressed both insulin- and TPA-induced glucose uptake. These results suggest that insulin-induced glucose uptake is mainly mediated by PI 3-kinase-PKCζ signaling, whereas phorbol ester-induced glucose uptake is mainly mediated by conventional PKC despite PI 3-kinase and PKCζ activations.
- Subjects
PROTEIN kinase C; INSULIN; PHORBOL esters; GLUCOSE
- Publication
IUBMB Life, 2001, Vol 51, Issue 5, p299
- ISSN
1521-6543
- Publication type
Article
- DOI
10.1080/152165401317190806