caa a22 4500 445298480 CHVBK 20180317142549.0 cr unu---uuuuu 170323e20101201xx s 000 0 eng 10.1007/s12013-010-9101-4 doi (NATIONALLICENCE)springer-10.1007/s12013-010-9101-4 Mechanism of Activation of PKB/Akt by the Protein Phosphatase Inhibitor Calyculin A [Elektronische Daten] [Mercedes Pozuelo-Rubio, Nick Leslie, Jane Murphy, Carol MacKintosh] The protein phosphatase inhibitor calyculin A activates PKB/Akt to ~50% of the activity induced by insulin-like growth factor 1 (IGF1) in HeLa cells promoting an evident increased phosphorylation of Ser473 despite the apparent lack of Thr308 phosphorylation of PKB. Nevertheless, calyculin A-induced activation of PKB seems to be dependent on basal levels of Thr308 phosphorylation, since a PDK1-dependent mechanism is required for calyculin A-dependent PKB activation by using embryonic stem cells derived from PDK1 wild-type and knockout mice. Data shown suggest that calyculin A-induced phosphorylation of Ser473 was largely blocked by LY294002 and SB-203580 inhibitors, indicating that both PI3-kinase/TORC2-dependent and SAPK2/p38-dependent protein kinases contributed to phosphorylation of Ser473 in calyculin A-treated cells. Additionally, our results suggest that calyculin A blocks the IGF1-dependent Thr308 phosphorylation and activation of PKB, likely due to an enhanced Ser612 phosphorylation of insulin receptor substrate 1 (IRS1), which can be inhibitory to its activation of PI3-kinase, a requirement for PDK1-induced Thr308 phosphorylation and IGF1-dependent activation of PKB. Our data suggest that PKB activity is most dependent on the level of Ser473 phosphorylation rather than Thr308, but basal levels of Thr308 phosphorylation are a requirement. Additionally, we suggest here that calyculin A regulates the IGF1-dependent PKB activation by controlling the PI3-kinase-associated IRS1 Ser/Thr phosphorylation levels. Springer Science+Business Media, LLC, 2010 PKB nationallicence Akt nationallicence Phosphorylation nationallicence Protein phosphatase inhibitor nationallicence IGF1 : Insulin-like growth factor 1 nationallicence IRS1 : Insulin receptor substrate 1 nationallicence MAPKAP-K2 : Mitogen-activated protein kinase-activated protein kinase 2 nationallicence PKB : Protein kinase B (also known as Akt) nationallicence PI3-kinase : Phosphatidylinositide 3-kinase nationallicence SAPK2 : Mitogen-activated protein (MAP) kinase stress-activated protein kinase-2/p38 nationallicence PDK1 : Phosphoinositide-dependent kinase-1 nationallicence AGC kinase family : cAMP-dependent protein kinases A, cGMP-dependent protein kinases G and phospholipid-dependent protein kinases C nationallicence mTOR : Mammalian target of rapamycin nationallicence TORC2 : Target of rapamycin complex 2 nationallicence DNA-PK : DNA-dependent protein kinase nationallicence Pozuelo-Rubio Mercedes Centro Andaluz de Biología Molecular y Medicina Regenerativa, CABIMER (SC4), Americo Vespucio s/n, 41092, Sevilla, Spain aut Leslie Nick Division of Molecular Physiology, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut Murphy Jane MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut MacKintosh Carol MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut Cell Biochemistry and Biophysics Humana Press Inc 58/3(2010-12-01), 147-156 1085-9195 58:3<147 2010 58 12013 https://doi.org/10.1007/s12013-010-9101-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s12013-010-9101-4 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pozuelo-Rubio Mercedes Centro Andaluz de Biología Molecular y Medicina Regenerativa, CABIMER (SC4), Americo Vespucio s/n, 41092, Sevilla, Spain aut NATIONALLICENCE 700 1- Leslie Nick Division of Molecular Physiology, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut NATIONALLICENCE 700 1- Murphy Jane MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut NATIONALLICENCE 700 1- MacKintosh Carol MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, DD1 5EH, Dundee, Scotland, UK aut NATIONALLICENCE 773 0- Cell Biochemistry and Biophysics Humana Press Inc 58/3(2010-12-01), 147-156 1085-9195 58:3<147 2010 58 12013 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer