RGD Reference Report - SH2-B promotes insulin receptor substrate 1 (IRS1)- and IRS2-mediated activation of the phosphatidylinositol 3-kinase pathway in response to leptin. - Rat Genome Database

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SH2-B promotes insulin receptor substrate 1 (IRS1)- and IRS2-mediated activation of the phosphatidylinositol 3-kinase pathway in response to leptin.

Authors: Duan, C  Li, M  Rui, L 
Citation: Duan C, etal., J Biol Chem. 2004 Oct 15;279(42):43684-91. Epub 2004 Aug 16.
RGD ID: 2302071
Pubmed: PMID:15316008   (View Abstract at PubMed)
PMCID: PMC3874232   (View Article at PubMed Central)
DOI: DOI:10.1074/jbc.M408495200   (Journal Full-text)

Leptin regulates energy homeostasis primarily by binding and activating its long form receptor (LRb). Deficiency of either leptin or LRb causes morbid obesity. Leptin stimulates LRb-associated JAK2, thus initiating multiple pathways including the Stat3 and phosphatidylinositol (PI) 3-kinase pathways that mediate leptin biological actions. Here we report that SH2-B, a JAK2-interacting protein, promotes activation of the PI 3-kinase pathway by recruiting insulin receptor substrate 1 (IRS1) and IRS2 in response to leptin. SH2-B directly bound, via its PH and SH2 domain, to both IRS1 and IRS2 both in vitro and in intact cells and mediated formation of a JAK2/SH2-B/IRS1 or IRS2 tertiary complex. Consequently, SH2-B dramatically enhanced leptin-stimulated tyrosine phosphorylation of IRS1 and IRS2 in HEK293 cells stably expressing LRb, thus promoting association of IRS1 and IRS2 with the p85 regulatory subunit of PI 3-kinase and phosphorylation and activation of Akt. SH2-B mutants with lower affinity for IRS1 and IRS2 exhibited reduced ability to promote association of JAK2 with IRS1, tyrosine phosphorylation of IRS1, and association of IRS1 with p85 in response to leptin. Moreover, deletion of the SH2-B gene impaired leptin-stimulated tyrosine phosphorylation of endogenous IRS1 in mouse embryonic fibroblasts (MEF), which was reversed by reintroduction of SH2-B. Similarly, SH2-B promoted growth hormone-stimulated tyrosine phosphorylation of IRS1 in both HEK293 and MEF cells. Our data suggest that SH2-B is a novel mediator of the PI 3-kinase pathway in response to leptin or other hormones and cytokines that activate JAK2.



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RGD Manual Annotations


  
Objects Annotated

Genes (Rattus norvegicus)
Irs1  (insulin receptor substrate 1)
Irs2  (insulin receptor substrate 2)
Jak2  (Janus kinase 2)
Sh2b1  (SH2B adaptor protein 1)

Genes (Mus musculus)
Irs1  (insulin receptor substrate 1)
Irs2  (insulin receptor substrate 2)
Jak2  (Janus kinase 2)
Sh2b1  (SH2B adaptor protein 1)

Genes (Homo sapiens)
IRS1  (insulin receptor substrate 1)
IRS2  (insulin receptor substrate 2)
JAK2  (Janus kinase 2)
SH2B1  (SH2B adaptor protein 1)


Additional Information