Proteomic studies of PP2A-B56gamma1 phosphatase complexes reveal phosphorylation-regulated partners in cardiac local signaling.
Defects of kinase-phosphatase signaling in cardiac myocytes contribute to human heart disease. The activity of one phosphatase, PP2A, is governed by B targeting subunits, including B56gamma1, expressed in heart cells. As the role of PP2A/B56gamma1 on the heart function remains largely unknown, this study sought to identify protein partners through unbiased, affinity purification-based proteomics combined with the functional validation. The results reveal multiple interactors that are localized in strategic cardiac sites to participate in Ca2+ homeostasis and gene expression, exemplified by the Ca pump, SERCA2a, and the splicing factor ASF/SF2. These results are corroborated by confocal imaging where adenovirally overexpressed B56gamma1 is found in z-line/t-tubule region and nuclear speckles. Importantly, overexpression of B56gamma1 in cultured myocytes dramatically impairs cell contractility. These results provide a global view of B56gamma1-regulated local signaling and heart function.
Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Xing Wang
XW
Zhou
Malkanthi
M
Mudannayake
Mariah
M
Green
Marisa S
MS
Gigena
Guanghui
G
Wang
Rong-Fong
RF
Shen
Terry B
TB
Rogers
D017398:Alternative Splicing; D002853:Chromatography, Liquid; D006801:Humans; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000737:chemistry*; D010766:Phosphorylation; D054648:Protein Phosphatase 2; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods*; D016601:RNA-Binding Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D000068103:Serine-Arginine Splicing Factors; D015398:Signal Transduction
D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; C503981:PPP2R5C protein, human; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases