title: Role of protein phosphatase-1 inhibitor-1 in cardiac physiology and pathophysiology.
abstract: The type 1 protein phosphatase (PP1) is a critical negative regulator of Ca(2+) cycling and contractility in the cardiomyocyte. In particular, it mediates restoration of cardiac function to basal levels, after beta-adrenergic stimulation, by dephosphorylating key phospho-proteins. PP1 is a holoenzyme comprised of its catalytic and auxiliary subunits. These regulatory proteins dictate PP1's subcellular localization, substrate specificity and activity. Amongst them, inhibitor-1 is of particular importance since it has been implicated as an integrator of multiple neurohormonal pathways, which finely regulate PP1 activity, at the level of the sarcoplasmic reticulum (SR). In fact, perturbations in the regulation of PP1 by inhibitor-1 have been implicated in the pathogenesis of heart failure, suggesting that inhibitor-1-based therapeutic interventions may ameliorate cardiac dysfunction and remodeling in the failing heart. This review will discuss the current views on the role of inhibitor-1 in cardiac physiology, its possible contribution to cardiac disease and its potential as a novel therapeutic strategy.
authors.affiliation: Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0575, USA.
authors.forename: Persoulla
authors.initials: P
authors.lastname: Nicolaou
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Hajjar
authors.forename: Evangelia G
authors.initials: EG
authors.lastname: Kranias
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology* / Q000503:physiopathology*; D006333:Heart Failure / Q000201:enzymology / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008954:Models, Biological; D010766:Phosphorylation; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013379:Substrate Specificity; D000099211:Phospholamban
chemical_list: D002118:Calcium; D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D000099211:Phospholamban; C021042:protein phosphatase inhibitor-1