Human Adenovirus Type 36 Enhances Glucose Uptake in Diabetic and Nondiabetic Human Skeletal Muscle Cells Independent of Insulin Signaling

  1. Zhong Q. Wang1,
  2. William T. Cefalu1,
  3. Xian H. Zhang1,
  4. Yongmei Yu1,
  5. Jianhua Qin1,
  6. Leslie Son1,
  7. Pamela M. Rogers2,
  8. Nazar Mashtalir2,
  9. Justin R. Bordelon1,
  10. Jianping Ye1 and
  11. Nikhil V. Dhurandhar2
  1. 1Division of Nutrition and Chronic Diseases, the Infections and Obesity Laboratory Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
  2. 2Infections and Obesity Laboratory Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
  1. Corresponding author: Zhong Q. Wang, zhong.wang{at}pbrc.edu

Abstract

OBJECTIVE—Human adenovirus type 36 (Ad-36) increases adiposity but improves insulin sensitivity in experimentally infected animals. We determined the ability of Ad-36 to increase glucose uptake by human primary skeletal muscle (HSKM) cells.

RESEARCH DESIGN AND METHODS—The effect of Ad-36 on glucose uptake and cell signaling was determined in HSKM cells obtained from type 2 diabetic and healthy lean subjects. Ad-2, another human adenovirus, was used as a negative control. Gene expression and proteins of GLUT1 and GLUT4 were measured by real-time PCR and Western blotting. Role of insulin and Ras signaling pathways was determined in Ad-36–infected HSKM cells.

RESULTS—Ad-36 and Ad-2 infections were confirmed by the presence of respective viral mRNA and protein expressions. In a dose-dependent manner, Ad-36 significantly increased glucose uptake in diabetic and nondiabetic HSKM cells. Ad-36 increased gene expression and protein abundance of GLUT1 and GLUT4, GLUT4 translocation to plasma membrane, and phosphatidylinositol 3-kinase (PI 3-kinase) activity in an insulin-independent manner. In fact, Ad-36 decreased insulin receptor substrate-1 (IRS-1) tyrosine phosphorylation and IRS-1–and IRS-2–associated PI 3-kinase activities. On the other hand, Ad-36 increased Ras gene expression and protein abundance, and Ras siRNA abrogated Ad-36–induced PI 3-kinase activation, GLUT4 protein abundance, and glucose uptake. These effects were not observed with Ad-2 infection.

CONCLUSIONS—Ad-36 infection increases glucose uptake in HSKM cells via Ras-activated PI 3-kinase pathway in an insulin-independent manner. These findings may provide impetus to exploit the role of Ad-36 proteins as novel therapeutic targets for improving glucose handling.

Footnotes

  • Published ahead of print at http://diabetes.diabetesjournals.org on 16 April 2008.

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    • Accepted April 10, 2008.
    • Received September 13, 2007.
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  1. Diabetes vol. 57 no. 7 1805-1813
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