Activation of protein phosphatase 1 by a selective phosphatase disrupting peptide reduces sarcoplasmic reticulum Ca<sup>2+</sup> leak in human heart failure

Fischer, Thomas; Eiringhaus, Jörg; Dybkova, Nataliya; Saadatmand, Alireza; Pabel, Steffen; Weber, Silvio; Wang, Yansong; Köhn, Maja; Tirilomis, Theodor; Ljubojevic, Senka; Renner, André; Gummert, Jan; Maier, Lars S.; Hasenfuß, Gerd; El‐Armouche, Ali; Sossalla, Samuel

doi:10.1002/ejhf.1297

Cited by 32 publications

(36 citation statements)

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“…PDPs are selective towards PP1 over related phosphatases, and thus, represent valuable tools to study PP1 function in physiological and pathological processes . Notably, recently it was shown that PDP treatment of human heart failure patient samples led to PP1 counteracting increased kinase activity and successfully sealing the arrhythmogenic Ca 2+ leak . In these studies, the cell‐active PDP3 was applied; this contained the unnatural amino acid para ‐benzoylphenylalanine ( Bpa ), which imparts metabolic stability to the PDP (Table ).…”

Section: Pdps Used For This Study and Their Ec50 Values For Deinhibitmentioning

confidence: 99%

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

et al. 2018

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Protein phosphatase‐1 (PP1)‐disrupting peptides (PDPs) are selective chemical modulators of PP1 that liberate the active PP1 catalytic subunit from regulatory proteins; thus allowing the dephosphorylation of nearby substrates. We have optimized the original cell‐active PDP3 for enhanced stability, and obtained insights into the chemical requirements for stabilizing this 23‐mer peptide for cellular applications. The optimized PDP‐ Nal was used to dissect the involvement of PP1 in the MAPK signaling cascade. Specifically, we have demonstrated that, in human osteosarcoma (U2OS) cells, phosphoMEK1/2 is a direct substrate of PP1, whereas dephosphorylation of phosphoERK1/2 is indirect and likely mediated through enhanced tyrosine phosphatase activity after PDP‐mediated PP1 activation. Thus, as liberators of PP1 activity, PDPs represent a valuable tool for identifying the substrates of PP1 and understanding its role in diverse signaling cascades.

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Section: Pdps Used For This Study and Their Ec50 Values For Deinhibitmentioning

confidence: 99%

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

et al. 2018

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“…; Fischer et al . ). However, scenarios in which phosphatases may actively regulate the amount of Ca 2+ released from the SR have been also reported (Lokuta et al .…”

Section: Discussionmentioning

confidence: 97%

“…The present study appears to be at odds with reports describing a decrease in the arrhythmogenic SR Ca 2+ leak as a consequence of PP‐1 activation (Fischer et al . ). In such cases, PDP3 has been used to counteract the increased kinase activity found in heart failure.…”

Section: Discussionmentioning

confidence: 97%

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Activation of endogenous protein phosphatase 1 enhances the calcium sensitivity of the ryanodine receptor type 2 in murine ventricular cardiomyocytes

Potenza

Janíček

Fernández-Tenorio

et al. 2020

The Journal of Physiology

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Key points Increased protein phosphatase 1 (PP‐1) activity has been found in end stage human heart failure. Although PP‐1 has been extensively studied, a detailed understanding of its role in the excitation–contraction coupling mechanism, in normal and diseased hearts, remains elusive. The present study investigates the functional effect of the PP‐1 activity on local Ca2+ release events in ventricular cardiomyocytes, by using an activating peptide (PDP3) for the stimulation of the endogenous PP‐1 protein. We report that acute de‐phosphorylation may increase the sensitivity of RyR2 channels to Ca2+ in situ, and that the RyR2‐serine2808 phosphorylation site may mediate such a process. Our approach unmasks the functional importance of PP‐1 in the regulation of RyR2 activity, suggesting a potential role in the generation of a pathophysiological sarcoplasmic reticulum Ca2+ leak in the diseased heart. Abstract Changes in cardiac ryanodine receptor (RyR2) phosphorylation are considered to be important regulatory and disease related post‐translational protein modifications. The extent of RyR2 phosphorylation is mainly determined by the balance of the activities of protein kinases and phosphatases, respectively. Increased protein phosphatase‐1 (PP‐1) activity has been observed in heart failure, although the regulatory role of this enzyme on intracellular Ca2+ handling remains poorly understood. To determine the physiological and pathophysiological significance of increased PP‐1 activity, we investigated how the PP‐1 catalytic subunit (PP‐1c) alters Ca2+ sparks in permeabilized cardiomyocytes and we also applied a PP‐1‐disrupting peptide (PDP3) to specifically activate endogenous PP‐1, including the one anchored on the RyR2 macromolecular complex. We compared wild‐type and transgenic mice in which the usually highly phosphorylated site RyR2‐S2808 has been ablated to investigate its involvement in RyR2 modulation (S2808A+/+). In wild‐type myocytes, PP‐1 increased Ca2+ spark frequency by two‐fold, followed by depletion of the sarcoplasmic reticulum Ca2+ store. Similarly, PDP3 transiently increased spark frequency and decreased sarcoplasmic reticulum Ca2+ load. RyR2 Ca2+ sensitivity, which was assessed by Ca2+ spark recovery analysis, was increased in the presence of PDP3 compared to a negative control peptide. S2808A+/+ cardiomyocytes did not respond to both PP‐1c and PDP3 treatment. Our results suggest an increased Ca2+ sensitivity of RyR2 upon de‐phosphorylation by PP‐1. Furthermore, we have confirmed the S2808 site as a target for PP‐1 and as a potential link between RyR2s modulation and the cellular response.

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“…The role of phosphatases activity on RyR2 phosphorylation was recently emphasized. It was shown that PP1 activation counteracts the increased kinase activity in human heart failure reducing SR Ca 2+ leak as well as cellular arrhythmias without significant changes in SR Ca 2+ load and contractility (Fischer et al, 2018).…”

Section: Post-translational Modifications Of Ryr2mentioning

confidence: 99%

Unbalance Between Sarcoplasmic Reticulum Ca2 + Uptake and Release: A First Step Toward Ca2 + Triggered Arrhythmias and Cardiac Damage

et al. 2020

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The present review focusses on the regulation and interplay of cardiac SR Ca 2+ handling proteins involved in SR Ca 2+ uptake and release, i.e., SERCa2/PLN and RyR2. Both RyR2 and SERCA2a/PLN are highly regulated by post-translational modifications and/or different partners' proteins. These control mechanisms guarantee a precise equilibrium between SR Ca 2+ reuptake and release. The review then discusses how disruption of this balance alters SR Ca 2+ handling and may constitute a first step toward cardiac damage and malignant arrhythmias. In the last part of the review, this concept is exemplified in different cardiac diseases, like prediabetic and diabetic cardiomyopathy, digitalis intoxication and ischemia-reperfusion injury.

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Activation of protein phosphatase 1 by a selective phosphatase disrupting peptide reduces sarcoplasmic reticulum Ca²⁺ leak in human heart failure

Cited by 32 publications

References 31 publications

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

Activation of endogenous protein phosphatase 1 enhances the calcium sensitivity of the ryanodine receptor type 2 in murine ventricular cardiomyocytes

Unbalance Between Sarcoplasmic Reticulum Ca2 + Uptake and Release: A First Step Toward Ca2 + Triggered Arrhythmias and Cardiac Damage

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Activation of protein phosphatase 1 by a selective phosphatase disrupting peptide reduces sarcoplasmic reticulum Ca2+ leak in human heart failure

Cited by 32 publications

References 31 publications

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

Interrogating PP1 Activity in the MAPK Pathway with Optimized PP1‐Disrupting Peptides

Activation of endogenous protein phosphatase 1 enhances the calcium sensitivity of the ryanodine receptor type 2 in murine ventricular cardiomyocytes

Unbalance Between Sarcoplasmic Reticulum Ca2 + Uptake and Release: A First Step Toward Ca2 + Triggered Arrhythmias and Cardiac Damage

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Activation of protein phosphatase 1 by a selective phosphatase disrupting peptide reduces sarcoplasmic reticulum Ca²⁺ leak in human heart failure