Disruption of insulin receptor substrate 2 causes type 2 diabetes because of liver insulin resistance and lack of compensatory beta-cell hyperplasia.
Kubota N,
Tobe K,
Terauchi Y,
Eto K,
Yamauchi T,
Suzuki R,
Tsubamoto Y,
Komeda K,
Nakano R,
Miki H,
Satoh S,
Sekihara H,
Sciacchitano S,
Lesniak M,
Aizawa S,
Nagai R,
Kimura S,
Akanuma Y,
Taylor SI,
Kadowaki T.
Department of Metabolic Disease, Graduate School of Medicine, University of Tokyo, Japan.
To investigate the role of insulin receptor substrate (IRS)-2 in vivo, we generated IRS-2-deficient mice by gene targeting. Although homozygous IRS-2-deficient mice (IRS-2-/- mice) had a body weight similar to wild-type mice, they progressively developed type 2 diabetes at 10 weeks. IRS-2-/- mice showed insulin resistance and a defect in the insulin-stimulated signaling pathway in liver but not in skeletal muscle. Despite insulin resistance, the amount of beta-cells was reduced to 83% of that in wild-type mice, which was in marked contrast to the 85% increase in the amount of beta-cells in IRS-1-deficient mice (IRS-1-/- mice) to compensate for insulin resistance. Thus, IRS-2 plays a crucial role in the regulation of beta-cell mass. On the other hand, insulin secretion by the same number of cells in response to glucose measured ex vivo was significantly increased in IRS-2-/- mice compared with wild-type mice but was decreased in IRS-1-/- mice. These results suggest that IRS-1 and IRS-2 may play different roles in the regulation of beta-cell mass and the function of individual beta-cells.
PMID: 11078455 [PubMed - indexed for MEDLINE]