Diabetes 53:1445-1451, 2004
© 2004 by the American Diabetes Association, Inc.
Role of Adipocyte-Derived Factors in Enhancing Insulin Signaling in Skeletal Muscle and White Adipose Tissue of Mice Lacking Acyl CoA:Diacylglycerol Acyltransferase 1
Hubert C. Chen1,2,3,
Meghana Rao1,
Mini P. Sajan4,5,
Mary Standaert4,5,
Yoshinori Kanoh4,5,
Atsushi Miura4,5,
Robert V. Farese, Jr.1,2,3, and
Robert V. Farese4,5
1 Gladstone Institute of Cardiovascular Disease, San Francisco, California
2 Cardiovascular Research Institute, University of California, San Francisco, California
3 Department of Medicine, University of California, San Francisco, California
4 James A. Haley Veterans Hospital, Tampa, Florida
5 Department of Medicine, University of South Florida, Tampa, Florida
Mice that lack acyl CoA:diacylglycerol acyltransferase 1 (DGAT1), a key enzyme in mammalian triglyceride synthesis, have decreased adiposity and increased insulin sensitivity. Here we show that insulin-stimulated glucose transport is increased in the skeletal muscle and white adipose tissue (WAT) of chow-fed DGAT1-deficient mice. This increase in glucose transport correlated with enhanced insulin-stimulated activities of phosphatidylinositol 3-kinase, protein kinase B (or Akt), and protein kinase C (PKC- ), three key molecules in the insulin-signaling pathway, and was associated with decreased levels of serine-phosphorylated insulin receptor substrate 1 (IRS-1), a molecule implicated in insulin resistance. Similar findings in insulin signaling were also observed in DGAT1-deficient mice fed a high-fat diet. Interestingly, the increased PKC- activity and decreased serine phosphorylation of IRS-1 were observed in chow-fed wild-type mice transplanted with DGAT1-deficient WAT, consistent with our previous finding that transplantation of DGAT1-deficient WAT enhances glucose disposal in wild-type recipient mice. Our findings demonstrate that DGAT1 deficiency enhances insulin signaling in the skeletal muscle and WAT, in part through altered expression of adipocyte-derived factors that modulate insulin signaling in peripheral tissues.
Address correspondence and reprint requests to Robert V. Farese, James A. Haley Veterans Hospital, ACOS-151, 13000 Bruce B. Downs Blvd., Tampa, FL 33612. E-mail: rfarese{at}hsc.usf.edu

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Copyright © 2004 by the American Diabetes Association.
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