Dataset Information

Calpain Cleavage of Junctophilin-2 generates a Spectrum of Calcium-dependent Cleavage Products and DNA-rich NT1-Fragment Domains in Cardiomyocytes - PRM Dataset

ABSTRACT: Calpains are calcium (Ca2+) activated neutral proteases that are involved in several essential signaling pathways. One Calpain-specific proteolytic target is Junctophilin-2 (JP2), an important structural protein of Ca2+ release units required for the excitation-contraction coupling in cardiomyocytes. While downregulation of JP2 by Calpain cleavage in mouse models of heart failure has been reported previously, the precise molecular identity of the Calpain cleavage sites and the (patho-) physiological roles of the JP2 proteolytic products remain controversial. We systematically analyzed the JP2 cleavage fragments as function of Calpain-1 versus Calpain-2 proteolytic activities, revealing that both Calpain isoforms preferentially cleave mouse JP2 at R565, but subsequently also at three additional secondary Calpain cleavage sites. We identified the Calpain-specific primary cleavage products not only in mouse but also in human iPSC-derived cardiomyocytes (hiPSC-CMs). Knockout of RyR2 in hiPSC-CMs destabilized JP2 resulting in an increase of the Calpain-specifc cleavage fragments. The primary N-terminal cleavage product (NT1) accumulated in the nucleus of mouse and human cardiomyocytes in a Ca2+ dependent manner, closely associated with DNA-rich chromosomal regions, where NT1 is proposed to function as a cardioprotective transcriptional regulator in heart failure. Taken together, our data suggest that stabilizing NT1 by preventing secondary cleavage events by Calpain and other proteases could be an important therapeutic target for future studies.

INSTRUMENT(S): TripleTOF 5600

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Heart, Regular Ventricular Cardiac Myocyte

DISEASE(S): Heart Failure

SUBMITTER: Christof Lenz

LAB HEAD: Christof Lenz

PROVIDER: PXD031424 | Pride | 2022-08-12

REPOSITORIES: Pride

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Publications

Calpain cleavage of Junctophilin-2 generates a spectrum of calcium-dependent cleavage products and DNA-rich NT<sub>1</sub>-fragment domains in cardiomyocytes.

Weninger Gunnar G Pochechueva Tatiana T El Chami Dana D Luo Xiaojing X Kohl Tobias T Brandenburg Sören S Urlaub Henning H Guan Kaomei K Lenz Christof C Lehnart Stephan E SE

Scientific reports 20220620 1

Calpains are calcium-activated neutral proteases involved in the regulation of key signaling pathways. Junctophilin-2 (JP2) is a Calpain-specific proteolytic target and essential structural protein inside Ca<sup>2+</sup> release units required for excitation-contraction coupling in cardiomyocytes. While downregulation of JP2 by Calpain cleavage in heart failure has been reported, the precise molecular identity of the Calpain cleavage sites and the (patho-)physiological roles of the JP2 proteolyt ...[more]

PMID: 35725601

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Project description:ABSTRACT Background: Viral myocarditis is a life-threatening illness that may lead to heart failure or cardiac arrhythmias. This study examined whether human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could be used to model the pathogenic processes of coxsackievirus-induced viral myocarditis and to screen antiviral therapeutics for efficacy. Methods and Results: Human iPSC-CMs were infected with a luciferase-expressing mutant of the coxsackievirus B3 strain (CVB3-Luc). Brightfield microscopy, immunofluorescence, and calcium imaging were used to characterize virally infected hiPSC-CMs. Viral proliferation on hiPSC-CMs was subsequently quantified using bioluminescence imaging. For drug screening, select antiviral compounds including interferon beta 1 (IFNβ1), ribavirin, pyrrolidine dithiocarbamate (PDTC), and fluoxetine were tested for their capacity to abrogate CVB3-Luc proliferation in hiPSC-CMs in vitro. The ability of some of these compounds to reduce CVB3-Luc proliferation in hiPSC-CMs was consistent with the reported drug effects in previous studies. Finally, mechanistic analyses via gene expression profiling of hiPSC-CMs infected with CVB3-Luc revealed an activation of viral RNA and protein clearance pathways within these hiPSC-CMs after IFNβ1 treatment. Conclusions: This study demonstrates that hiPSC-CMs express the coxsackievirus and adenovirus receptor, are susceptible to coxsackievirus infection, and can be used to confirm antiviral drug efficacy. Our results suggest that the hiPSC-CM/CVB3-Luc assay is a sensitive platform that could be used to screen novel antiviral therapeutics for their effectiveness in a high-throughput fashion. For this experiment, human induced pluripotent stem cell derived cardiomyocytes were infected with coxsackievirus at multiplicity of infection (MOI) of 5 for 8 hours. Cells were treated with and without interferon beta 1 in order to determine if treatment activates antiviral response genes and/or viral clearance pathways. 4 total samples (2 for each condition) were analyzed

Dataset Information

Calpain Cleavage of Junctophilin-2 generates a Spectrum of Calcium-dependent Cleavage Products and DNA-rich NT1-Fragment Domains in Cardiomyocytes - PRM Dataset

Publications

Calpain cleavage of Junctophilin-2 generates a spectrum of calcium-dependent cleavage products and DNA-rich NT<sub>1</sub>-fragment domains in cardiomyocytes.

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