SH2B1 regulation of energy balance, body weight, and glucose metabolism

摘要

The Src homology 2B(SH2B)family members(SH2B1,SH2B2 and SH2B3)are adaptor signaling proteins containing characteristic SH2 and PH domains.SH2B1(also called SH2-B and PSM)and SH2B2(also called APS)are able to form homo-or hetero-dimers via their N-terminal dimerization domains.Their C-terminal SH2 domains bind to tyrosyl phosphorylated proteins,including Janus kinase 2(JAK2),TrkA,insulin receptors,insulin-like growth factor-1 receptors,insulin receptor substrate-1(IRS1),and IRS2.SH2B1 enhances leptin signaling by both stimulating JAK2 activity and assembling a JAK2/IRS1/2 signaling complex.SH2B1 promotes insulin signaling by both enhancing insulin receptor catalytic activity and protecting against dephosphorylation of IRS proteins.Accordingly,genetic deletion of SH2B1 results in severe leptin resistance,insulin resistance,hyperphagia,obesity,and type 2 diabetes in mice.Neuronspecific overexpression of SH2B1βtransgenes protects against diet-induced obesity and insulin resistance.SH2B1 in pancreaticβcells promotesβcell expansion and insulin secretion to counteract insulin resistance in obesity.Moreover,numerous SH2B1 mutations are genetically linked to leptin resistance,insulin resistance,obesity,and type 2 diabetes in humans.Unlike SH2B1,SH2B2 and SH2B3 are not required for the maintenance of normal energy and glucose homeostasis.The metabolic function of the SH2B family is conserved from insects to humans.