Green tea (-)-epigallocatechin gallate suppresses IGF-I and IGF-II stimulation of 3T3-L1 adipocyte glucose uptake via the glucose transporter 4, but not glucose transporter 1 pathway

Hui Chen Ku, Yi Wei Tsuei, Chung Cheng Kao, Jueng Tsueng Weng, Li Jane Shih, Hsin Huei Chang, Chi Wei Liu, Shu Wei Tsai, Yow Chii Kuo, Yung Hsi Kao

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12 Scopus citations

Abstract

This study investigated the pathways involved in EGCG modulation of insulin-like growth factor (IGF)-stimulated glucose uptake in 3T3-L1 adipocytes. EGCG inhibited IGF-I and IGF-II stimulation of adipocyte glucose uptake with dose and time dependencies. EGCG at 20. μM for 2. h decreased IGF-I- and IGF-II-stimulated glucose uptake by 59% and 64%, respectively. Pretreatment of adipocytes with antibody against the EGCG receptor (also known as the 67-kDa laminin receptor; 67LR), prevented the effects of EGCG on IGF-increased glucose uptake, but pretreatment with normal rabbit immunoglobulin did not. This suggests that the 67LR mediates the anti-IGF effect of EGCG on adipocyte glucose uptake. Further analysis indicated EGCG, IGF-I, and IGF-II did not alter total levels of GLUT1 or GLUT4 protein. However, EGCG prevented the IGF-increased GLUT4 levels in the plasma membrane and blocked the IGF-decreased GLUT4 levels in low-density microsomes. Neither EGCG nor its combination with IGF altered GLUT1 protein levels in the plasma membrane and low-density microsomes. EGCG also suppressed the IGF-stimulated phosphorylation of IGF signaling molecules, PKCζ/λ, but not AKT and ERK1/2, proteins. This study suggests that EGCG suppresses IGF stimulation of 3T3-L1 adipocyte glucose uptake through inhibition of the GLUT4 translocation, but not through alterations of the GLUT1 pathway.

Original languageEnglish
Pages (from-to)46-55
Number of pages10
JournalGeneral and Comparative Endocrinology
Volume199
DOIs
StatePublished - 1 Apr 2014

Keywords

  • Adipocyte glucose uptake
  • Epigallocatechin gallate
  • Glucose transporter
  • Green tea
  • Insulin-like growth factor

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