title: Interaction of Janus kinases JAK-1 and JAK-2 with the insulin receptor and the insulin-like growth factor-1 receptor.
abstract: Insulin and insulin-like growth factor-1 (IGF-1) treatment of cells overexpressing the insulin receptor or the IGF-1 receptor promotes phosphorylation and activation of Janus kinases JAK-1 and JAK-2 but not of TYK-2. With insulin, we observed maximal phosphorylation of JAK-1 within 2 min (5.2 +/- 0.6-fold) and maximal phosphorylation of JAK-2 within 10 min (2.4 +/- 0.6-fold). In cells incubated with IGF-1, we found maximal phosphorylation of JAK-2 within 2 min (1.9 +/- 0.2-fold) and of JAK-1 within 5 min (4.5 +/- 0.4-fold). The JAKs from insulin- or IGF-1-stimulated cells were activated, as shown by their autophosphorylation in vitro. Moreover, they were able to phosphorylate in vitro native insulin receptor substrate (IRS)-1 and a fragment of IRS-2 (GST-IRS-2591-786). Comparison of 32P-peptide maps of IRS-1 phosphorylated in vitro by the insulin receptor vs. JAK-1 showed the occurrence of different phosphopeptides, suggesting that different sites are likely to be phosphorylated by the two kinases. Finally, coprecipitation of receptors and JAK-1 was seen, and phosphorylation of both receptors was found to be necessary for receptor binding to JAK-1. Two domains of JAK- 1 are involved in the formation of the complex between receptor and JAK-1, i.e. the N-terminal portion containing JH7 and JH6 domains, and the C-terminal kinase domain (JH1 domain). Taking our data together, we conclude that: 1) insulin and IGF-1 lead to phosphorylation and activation of JAK-1 and JAK-2 in intact cells; 2) phosphorylation of IRS-I by JAK-1 seems to occur on sites different from those phosphorylated by the insulin receptor; 3) JAK-1 interacts directly with phosphorylated insulin and IGF-1 receptors; and 4) the JH7-JH6 and JH1 domains of JAK-1 are responsible for the interaction with insulin and IGF-1 receptors.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale U 145, Faculté de Médecine, Nice, France.
authors.forename: P
authors.initials: P
authors.lastname: Gual
authors.forename: V
authors.initials: V
authors.lastname: Baron
authors.forename: V
authors.initials: V
authors.lastname: Lequoy
authors.forename: E
authors.initials: E
authors.lastname: Van Obberghen
mesh_terms: D016475:3T3 Cells; D000818:Animals; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D051379:Mice; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism*
chemical_list: D007328:Insulin; D011518:Proto-Oncogene Proteins; D007334:Insulin-Like Growth Factor I; D011505:Protein-Tyrosine Kinases; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507905:Jak1 protein, mouse; C507926:Jak2 protein, mouse; D053613:Janus Kinase 1; D053614:Janus Kinase 2