Insulin receptor substrates, including Irs1 and Irs2, integrate insulin and IGF receptor signals with heterologous pathways to coordinate growth and metabolism. Since Irs2 is thought to be especially important in hepatic nutrient homeostasis, we deleted Irs1 from hepatocytes of WT mice (called LKO) or genetically insulin-resistant Irs1–/– mice (called LKO::Irs1–/–). Viable LKO::Irs1–/– mice were 70% smaller than WT or LKO mice, and 40% smaller than Irs1–/– mice. Hepatic insulin receptors were functional in all the mice, but insulin signaling via the Akt—FoxO1 pathway was reduced in Irs1–/– and LKO liver, and undetected in LKO::Irs1–/– liver; however, Gsk3β phosphorylation (Ser9) and hepatic glycogen stores were nearly normal in all of the mice. LKO and Irs1–/– mice developed insulin resistance and glucose intolerance that never progressed to diabetes, whereas LKO::Irs1–/– mice developed hyperglycemia and hyperinsulinemia immediately after birth. Regardless, few hepatic genes changed expression significantly in Irs1–/– or LKO mice, whereas hundreds of genes changed in LKO::Irs1–/– mice — including elevated levels of Pck1, G6pc, Ppargc1, Pparg, and Igfbp1. Thus, signals delivered by Irs1 or Irs2 regulate hepatic gene expression that coordinates glucose homeostasis and systemic growth.
Xiaocheng Dong, Sunmin Park, Xueying Lin, Kyle Copps, Xianjin Yi, Morris F. White
Usage data is cumulative from December 2018 through December 2019.
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.