Novel role of the protein phosphatase 1 regulatory subunit PPP1R3A in atrial fibrillation

2018 ◽  
Vol 124 ◽  
pp. 108
Author(s):  
Katherina Alsina ◽  
Mohit Hulsurkar ◽  
Chunxia Yao ◽  
Barbara Langer ◽  
David Chiang ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit

scholarly journals Ref2, a regulatory subunit of the yeast protein phosphatase 1, is a novel component of cation homoeostasis

2010 ◽  
Vol 426 (3) ◽  
pp. 355-364 ◽  
Author(s):  
Jofre Ferrer-Dalmau ◽  
Asier González ◽  
Maria Platara ◽  
Clara Navarrete ◽  
José L. Martínez ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Living Organism ◽  
Calcium Sensitivity ◽  
Growth Conditions ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Alkaline Ph ◽  
Yeast Protein ◽  
Increased Sensitivity

Maintenance of cation homoeostasis is a key process for any living organism. Specific mutations in Glc7, the essential catalytic subunit of yeast protein phosphatase 1, result in salt and alkaline pH sensitivity, suggesting a role for this protein in cation homoeostasis. We screened a collection of Glc7 regulatory subunit mutants for altered tolerance to diverse cations (sodium, lithium and calcium) and alkaline pH. Among 18 candidates, only deletion of REF2 (RNA end formation 2) yielded increased sensitivity to these conditions, as well as to diverse organic toxic cations. The Ref2F374A mutation, which renders it unable to bind Glc7, did not rescue the salt-related phenotypes of the ref2 strain, suggesting that Ref2 function in cation homoeostasis is mediated by Glc7. The ref2 deletion mutant displays a marked decrease in lithium efflux, which can be explained by the inability of these cells to fully induce the Na+-ATPase ENA1 gene. The effect of lack of Ref2 is additive to that of blockage of the calcineurin pathway and might disrupt multiple mechanisms controlling ENA1 expression. ref2 cells display a striking defect in vacuolar morphogenesis, which probably accounts for the increased calcium levels observed under standard growth conditions and the strong calcium sensitivity of this mutant. Remarkably, the evidence collected indicates that the role of Ref2 in cation homoeostasis may be unrelated to its previously identified function in the formation of mRNA via the APT (for associated with Pta1) complex.

Abstract 70: Protein Phosphatase 1 Contributes to Atrial Stunning in Atrial Fibrillation

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Srikanth Perike ◽  
Xander Wehrens ◽  
Dawood Darbar ◽  
Mark McCauley
Keyword(s):  
Atrial Fibrillation ◽  
Light Chain ◽  
Protein Phosphatase ◽  
Myosin Light Chain ◽  
Stroke Risk ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Future Studies ◽  
Hek Cells

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia, and increases a patient’s stroke risk five-fold. Reduced atrial contractility (stunning) is observed in AF and contributes to stroke risk; however, the mechanisms responsible for atrial stunning in AF are unknown. Recent data from our laboratory indicate that protein phosphatase 1 (PP1) dephosphorylation of myosin light chain 2a (MLC2a) may contribute to atrial stunning in AF. Objective: To determine how the PP1 regulatory subunit 12C (PPP1R12C) and catalytic (PPP1c) subunits modify atrial sarcomere phosphorylation in AF. Methods: We evaluated the protein expression, binding and phosphorylation among PPP1R12C, PPP1c, and MLC2a in transfected HL-1 cells, murine atrial tissue (Pitx2null +/– mice, with a genetic predisposition AF), and in HEK cells. An inhibitor of PPP1R12C phosphorylation, BDP5290, was used to enhance the PPP1R12C-PPP1C interaction. Results: In Pitx2 null +/– mice, PPP1R12C was increased by 2-fold ( P <0.01) and associated with a 40% reduction in S-19-MLC2a phosphorylation versus WT mice ( P <0.058). BDP5290 increased PPP1R12C-PPP1C binding by >3-fold in HL-1 cells ( P <0.01). BDP5290 reduced MLC2a phosphorylation by 40% through an enhanced interaction with PPP1R12C by >3-fold in HEK cells ( P <0.01). Conclusion: In Pitx2 null+/- mice, increased expression of PPP1R12C is associated with PP1 holoenzyme targeting to sarcomeric MLC2a, and is associated with reduced S19-MLC2a phosphorylation. Additionally, BDP5290 enhances the PPP1R12C-PPP1C interaction and models PP1 activity in AF. Future studies will examine the effects of both AF and BDP5290 upon atrial contractility in vitro.

Abstract WMP39: Protein Phosphatase 1 Regulatory Subunit 12C Contributes to Atrial Myosin Light Chain Dephosphorylation in Atrial Fibrillation

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Srikanth Perike ◽  
Katherina M Alsina ◽  
Arvind Sridhar ◽  
Dawood Darbar ◽  
Xander Wehrens ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Light Chain ◽  
Protein Phosphatase ◽  
Myosin Light Chain ◽  
Stroke Risk ◽  
Contractile Function ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Western Blots ◽  
Atrial Myosin

Background: Atrial fibrillation (AF) increases stroke risk five-fold. Atrial hypocontractility from atrial myosin light chain (MLC2a) dephosphorylation contributes to stroke risk in AF. Recent proteomic data has shown increased protein phosphatase 1 subunit 12C (PPP1R12C) targeting to MLC2a in AF. However, it is unclear whether PPP1R12C causes MLC2a dephosphorylation in AF. Objective: Determine whether increased PPP1R12C expression causes MLC2a dephosphorylation and increases AF risk. Methods: Western blots and co-IPs were performed to evaluate the relationship among PPP1R12C, PP1c and MLC2a in human atrial tissues (AF vs SR). Mice with either a knockout (KO) or lentiviral (LV) cardiac overexpression of PPP1R12C were evaluated with invasive EP studies for AF inducibility vs WT controls. Results: In human AF, PPP1R12C was increased 4-fold ( P <0.005, n=6) with an 88% reduction in S-19-MLC2a phosphorylation ( P <0.05, n=4). PPP1R12C-PP1c and PPP1R12C-MLC2a binding was increased 2-fold in AF ( P <0.05, n=6). AF burden in LV-12C mice increased nearly tenfold vs. KO and WT mice ( P <0.05, n=6). Conclusion: In human AF, increased PPP1R12C expression is associated with reduced P-MLC2a through enhanced binding with the PP1c catalytic subunit. This dephosphorylation is a likely contributor to atrial hypocontractility and stroke risk in AF. Additionally, increased PPP1R12C expression in mice increases AF risk. Future studies will examine the effects of increased PPP1R12C expression upon atrial contractile function in mice.

scholarly journals Loss of Protein Phosphatase 1 Regulatory Subunit PPP1R3A Promotes Atrial Fibrillation

Circulation ◽  
2019 ◽  
Vol 140 (8) ◽  
pp. 681-693 ◽  
Author(s):  
Katherina M. Alsina ◽  
Mohit Hulsurkar ◽  
Sören Brandenburg ◽  
Daniel Kownatzki-Danger ◽  
Christof Lenz ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Endoplasmic Reticulum ◽  
Knockout Mice ◽  
Protein Phosphatase ◽  
Calcium Atpase ◽  
Stimulated Emission ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Wild Type ◽  
Endoplasmic Reticulum Calcium

Background: Abnormal calcium (Ca 2+ ) release from the sarcoplasmic reticulum (SR) contributes to the pathogenesis of atrial fibrillation (AF). Increased phosphorylation of 2 proteins essential for normal SR-Ca 2+ cycling, the type-2 ryanodine receptor (RyR2) and phospholamban (PLN), enhances the susceptibility to AF, but the underlying mechanisms remain unclear. Protein phosphatase 1 (PP1) limits steady-state phosphorylation of both RyR2 and PLN. Proteomic analysis uncovered a novel PP1-regulatory subunit (PPP1R3A [PP1 regulatory subunit type 3A]) in the RyR2 macromolecular channel complex that has been previously shown to mediate PP1 targeting to PLN. We tested the hypothesis that reduced PPP1R3A levels contribute to AF pathogenesis by reducing PP1 binding to both RyR2 and PLN. Methods: Immunoprecipitation, mass spectrometry, and complexome profiling were performed from the atrial tissue of patients with AF and from cardiac lysates of wild-type and Pln -knockout mice. Ppp1r3a -knockout mice were generated by CRISPR-mediated deletion of exons 2 to 3. Ppp1r3a -knockout mice and wild-type littermates were subjected to in vivo programmed electrical stimulation to determine AF susceptibility. Isolated atrial cardiomyocytes were used for Stimulated Emission Depletion superresolution microscopy and confocal Ca 2+ imaging. Results: Proteomics identified the PP1-regulatory subunit PPP1R3A as a novel RyR2-binding partner, and coimmunoprecipitation confirmed PPP1R3A binding to RyR2 and PLN. Complexome profiling and Stimulated Emission Depletion imaging revealed that PLN is present in the PPP1R3A-RyR2 interaction, suggesting the existence of a previously unknown SR nanodomain composed of both RyR2 and PLN/sarco/endoplasmic reticulum calcium ATPase-2a macromolecular complexes. This novel RyR2/PLN/sarco/endoplasmic reticulum calcium ATPase-2a complex was also identified in human atria. Genetic ablation of Ppp1r3a in mice impaired binding of PP1 to both RyR2 and PLN. Reduced PP1 targeting was associated with increased phosphorylation of RyR2 and PLN, aberrant SR-Ca 2+ release in atrial cardiomyocytes, and enhanced susceptibility to pacing-induced AF. Finally, PPP1R3A was progressively downregulated in the atria of patients with paroxysmal and persistent (chronic) AF. Conclusions: PPP1R3A is a novel PP1-regulatory subunit within the RyR2 channel complex. Reduced PPP1R3A levels impair PP1 targeting and increase phosphorylation of both RyR2 and PLN. PPP1R3A deficiency promotes abnormal SR-Ca 2+ release and increases AF susceptibility in mice. Given that PPP1R3A is downregulated in patients with AF, this regulatory subunit may represent a new target for AF therapeutic strategies.

Role of protein phosphatase 1 glycogen-associated regulatory subunit in asthma

2018 ◽  
Author(s):  
Mayra D. Álvarez-Santos ◽  
Marisol Alvarez-González ◽  
Elizabeth Eslava-De Jesus ◽  
Yazmín Pérez-Del Valle ◽  
Javier R. Ambrosio ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit

scholarly journals RIPK1 dephosphorylation and kinase activation by PPP1R3G/PP1γ promote apoptosis and necroptosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingchun Du ◽  
Yougui Xiang ◽  
Hua Liu ◽  
Shuzhen Liu ◽  
Ashwani Kumar ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Type I ◽  
Interacting Protein ◽  
Kinase Activation ◽  
Necrosis Factor

AbstractReceptor-interacting protein kinase 1 (RIPK1) is a key regulator of inflammation and cell death. Many sites on RIPK1, including serine 25, are phosphorylated to inhibit its kinase activity and cell death. How these inhibitory phosphorylation sites are dephosphorylated is poorly understood. Using a sensitized CRISPR whole-genome knockout screen, we discover that protein phosphatase 1 regulatory subunit 3G (PPP1R3G) is required for RIPK1-dependent apoptosis and type I necroptosis. Mechanistically, PPP1R3G recruits its catalytic subunit protein phosphatase 1 gamma (PP1γ) to complex I to remove inhibitory phosphorylations of RIPK1. A PPP1R3G mutant which does not bind PP1γ fails to rescue RIPK1 activation and cell death. Furthermore, chemical prevention of RIPK1 inhibitory phosphorylations or mutation of serine 25 of RIPK1 to alanine largely restores cell death in PPP1R3G-knockout cells. Finally, Ppp1r3g−/− mice are protected from tumor necrosis factor-induced systemic inflammatory response syndrome, confirming the important role of PPP1R3G in regulating apoptosis and necroptosis in vivo.

scholarly journals Phostensin Enables Lymphocyte Integrin Activation and Population of Peripheral Lymphoid Organs

2021 ◽  
Author(s):  
Mark Ginsberg ◽  
Hao Sun ◽  
Alexandre Gingras ◽  
HoSup Lee ◽  
Frederic Lagarrigue ◽  
...  
Keyword(s):  
T Cells ◽  
Protein Phosphatase ◽  
Protein Phosphatase 1 ◽  
Regulatory Subunit ◽  
Lymphoid Tissues ◽  
Transfer Model ◽  
Integrin Activation ◽  
Affinity Tag ◽  
Human T Cells ◽  
Apparently Healthy

Rap1 GTPase drives assembly of the Mig10/RIAM/lamellipodin–Integrin–Talin (MIT) complex that enables integrin dependent lymphocyte functions. Here we used tandem affinity tag based proteomics to isolate and analyze the MIT complex and reveal that Phostensin (PTSN), a regulatory subunit of protein phosphatase 1, is a component of the complex. PTSN mediates dephosphorylation of Rap1 thereby preserving the activity and membrane localization of Rap1 to stabilize the MIT complex. CRISPR/Cas9-induced deletion of PPP1R18, which encodes PTSN, markedly suppresses integrin activation in Jurkat human T cells. We generated apparently healthy Ppp1r18 null mice that manifest lymphocytosis and reduced population of peripheral lymphoid tissues ascribable to defective activation of integrins. Ppp1r18 null T cells exhibit reduced capacity to induce colitis in a murine adoptive transfer model. Thus, PTSN enables lymphocyte integrin mediated functions by dephosphorylating Rap1 to stabilize the MIT complex. As a consequence, loss of PTSN ameliorates T cell mediated colitis.

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