title: Ras GTPase-activating protein binds to Akt and is required for its activation.
abstract: RasGAP (Ras GTPase-activating protein) is a negative regulator as well as a downstream effector of Ras. To identify partners of RasGAP we used it as the bait in a yeast two-hybrid screen. This resulted in discovering its interaction with Akt. Overexpression of RasGAP or a mutant lacking the GTPase-activating domain (nGAP) enhanced phosphorylation and activity of Akt, which was dependent on the upstream integrin-linked kinase. Also, nGAP protected the cells against staurosporin-induced apoptosis through an Akt-dependent pathway. To determine the role of RasGAP in receptor-mediated activation of Akt, we used short hairpin RNA interference to knock out endogenous RasGAP expression. Although this procedure resulted in enhanced Ras activity, it inhibited Akt phosphorylation. Thus, we propose that Ras-GAP interacts with Akt and is necessary for its activation, possibly via integrin-linked kinase-mediated phosphorylation of Ser-473. The data suggest that this effect is independent of Ras activity.
authors.affiliation: Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
authors.forename: Yingzi
authors.initials: Y
authors.lastname: Yue
authors.forename: Jaqueline
authors.initials: J
authors.lastname: Lypowy
authors.forename: Nadia
authors.initials: N
authors.lastname: Hedhli
authors.forename: Maha
authors.initials: M
authors.lastname: Abdellatif
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D017209:Apoptosis; D015153:Blotting, Western; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D004789:Enzyme Activation; D020287:In Situ Nick-End Labeling; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012313:RNA / Q000737:chemistry; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D013997:Time Factors; D020798:Two-Hybrid System Techniques; D020703:ras GTPase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D020703:ras GTPase-Activating Proteins; D012313:RNA; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019311:Staurosporine