title: Protein Kinase A (PKA) Phosphorylation of Shp2 Protein Inhibits Its Phosphatase Activity and Modulates Ligand Specificity.
abstract: Pathological cardiac hypertrophy (an increase in cardiac mass resulting from stress-induced cardiac myocyte growth) is a major factor underlying heart failure. Src homology 2 domain-containing phosphatase (Shp2) is critical for cardiac function because mutations resulting in loss of Shp2 catalytic activity are associated with congenital cardiac defects and hypertrophy. We identified a novel mechanism of Shp2 inhibition that may promote cardiac hypertrophy. We demonstrate that Shp2 is a component of the protein kinase A anchoring protein (AKAP)-Lbc complex. AKAP-Lbc facilitates PKA phosphorylation of Shp2, which inhibits Shp2 phosphatase activity. We identified two key amino acids in Shp2 that are phosphorylated by PKA. Thr-73 contributes a helix cap to helix αB within the N-terminal SH2 domain of Shp2, whereas Ser-189 occupies an equivalent position within the C-terminal SH2 domain. Utilizing double mutant PKA phosphodeficient (T73A/S189A) and phosphomimetic (T73D/S189D) constructs, in vitro binding assays, and phosphatase activity assays, we demonstrate that phosphorylation of these residues disrupts Shp2 interaction with tyrosine-phosphorylated ligands and inhibits its protein-tyrosine phosphatase activity. Overall, our data indicate that AKAP-Lbc integrates PKA and Shp2 signaling in the heart and that AKAP-Lbc-associated Shp2 activity is reduced in hypertrophic hearts in response to chronic β-adrenergic stimulation and PKA activation. Therefore, although induction of cardiac hypertrophy is a multifaceted process, inhibition of Shp2 activity through AKAP-Lbc-anchored PKA is a previously unrecognized mechanism that may promote this compensatory response.
authors: From the Department of Pharmacology.
authors: Brian T
authors: BT
authors: Burmeister
authors: From the Department of Pharmacology.
authors: Li
authors: L
authors: Wang
authors: Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, United Kingdom, and.
authors: Matthew G
authors: MG
authors: Gold
authors: From the Department of Pharmacology.
authors: Randal A
authors: RA
authors: Skidgel
authors: From the Department of Pharmacology, University of Illinois Cancer Center, and Center for Cardiovascular Research, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, 60612, the Jessie Brown Veterans Affairs Medical Center, Chicago, Illinois, 60612 obryanj@uic.edu.
authors: John P
authors: JP
authors: O'Bryan
authors: From the Department of Pharmacology.
authors: Graeme K
authors: GK
authors: Carnegie
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000235:genetics*; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013912:Threonine / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry; D018909:src Homology Domains
chemical_list: D008024:Ligands; D011943:Receptors, Adrenergic, beta; D013912:Threonine; D014443:Tyrosine; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11
keywords: A-kinase Anchoring Protein (AKAP); Cardiac Hypertrophy; PKA; Signal Transduction; Tyrosine-protein Phosphatase (Tyrosine Phosphatase)