Published May 2, 2005 - More info
Hepatic insulin resistance is a critical component in the development of type 2 diabetes mellitus. In many cases, insulin resistance in liver is associated with reduced expression of both major insulin receptor substrate (IRS) proteins, IRS-1 and IRS-2. To investigate the specific functions of IRS-1 and IRS-2 in regulating liver function in vivo, we developed an adenovirus-mediated RNA interference technique in which short hairpin RNAs (shRNAs) are used to knock down IRS-1, IRS-2, or both, by 70–80% in livers of WT mice. The knockdown of IRS-1 resulted in an upregulation of the gluconeogenic enzymes glucose-6 phosphatase and phosphoenolpyruvate carboxykinase, as well as a marked increase in hepatic nuclear factor–4 α. Decreased IRS-1 was also associated with a decrease in glucokinase expression and a trend toward increased blood glucose, whereas knockdown of IRS-2 resulted in the upregulation of lipogenic enzymes SREBP-1c and fatty acid synthase, as well as increased hepatic lipid accumulation. The concomitant injection of IRS-1 and IRS-2 adenoviral shRNAs resulted in systemic insulin resistance, glucose intolerance, and hepatic steatosis. The alterations in the dual-knockdown mice were associated with defective Akt activation and Foxo1 phosphorylation. Taken together, our results demonstrate that hepatic IRS-1 and IRS-2 have complementary roles in the control of hepatic metabolism, with IRS-1 more closely linked to glucose homeostasis and IRS-2 more closely linked to lipid metabolism.
Cullen M. Taniguchi, Kohjiro Ueki, C. Ronald Kahn
Original citation: J. Clin. Invest.115:718–727 (2005). doi:10.1172/JCI23187
Citation for this corrigendum: J. Clin. Invest.115:1388 (2005). doi:10.1172/JCI23187C1
Due to an error in manuscript preparation, an incorrect shRNA sequence for IRS2 was published. The correct hairpin sequence is a 19-nt stretch beginning from nt 703 of the published IRS2 cDNA sequence (XM_357863). The oligonucleotides cloned into the U6 construct for the IRS2U6 adenovirus are as follows: tcgagGTGACGCTGCAGCTTATGAttcaagagaTCATAAGCTGCAGCGTCACttttt (forward) and ctagAAAAAGTGACGCTGCAGCTTATGAtctcttgaaTCATAAGCTGCAGCGTCACc (reverse). In addition, the shRNA cassettes were cloned into the adenoviral cosmid pAxcwit, which lacks a promoter, and not the cosmid pAxCAwtit, as published.
The authors regret this error.