title: Insulin increase in MAP kinase phosphorylation is shifted to early time-points by overexpressing APS, while Akt phosphorylation is not influenced.
abstract: Upon insulin stimulation, the adaptor protein APS is recruited to the insulin receptor and tyrosine phosphorylated. APS initiates the insulin-induced TC10 cascade which participates to GLUT4 translocation to the plasma membrane. Nevertheless, the molecular mechanism that governs APS and its SH2 and PH domains action on the insulin transduction cascade is not yet fully understood. Here, we show that APS co-immunoprecipitates with the class I PI 3-kinase regulatory subunit p85, through its SH2 domain but that APS does not modulate neither PtdIns(3,4,5)P3 levels nor Akt phosphorylation provoked by insulin. We have confirmed a previously described positive effect of APS overexpression on insulin-induced MAPK phosphorylation upregulation. Consequently, we analyzed the role of SH2 and PH domains of APS in the APS increased MAPK phosphorylation observed upon insulin stimulation and correlated this with the membrane localization of the protein. The effect observed on MAPK phosphorylation requires the intact PH binding domain of APS as well as its SH2 domain.
authors.affiliation: Institute of Interdisciplinary Research (IRIBHM), School of Medicine, Université Libre de Bruxelles, Campus Erasme, route de Lennik 808, Brussels, Belgium.
authors.forename: Sheela
authors.initials: S
authors.lastname: Onnockx
authors.forename: Jingwei
authors.initials: J
authors.lastname: Xie
authors.forename: Chantal
authors.initials: C
authors.lastname: Degraef
authors.forename: Christophe
authors.initials: C
authors.lastname: Erneux
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pirson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation; D007295:Inositol Phosphates / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017354:Point Mutation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D007295:Inositol Phosphates; D007328:Insulin; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C118500:inositol 3,4,5-trisphosphate