Genetic Inhibition of Nuclear Factor of Activated T-Cell c2 Prevents Atrial Fibrillation in CREM Transgenic Mice

Authors

Li Ni
Satadru K Lahiri
Jiali Nie
Xiaolu Pan
Issam Abu-Taha
Julia O Reynolds
Hannah M Campbell
Haihao Wang
Markus Kamler
Wilhelm Schmitz
Frank Ulrich Müller
Na Li
Xiang Wei
Dao Wen Wang
Dobromir Dobrev
Xander H T Wehrens

Publication Date

10-21-2022

Journal

Cardiovascular Research

DOI

10.1093/cvr/cvab325

PMID

34648001

PMCID

PMC9586567

PubMedCentral® Posted Date

10-14-2021

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Humans, Mice, Atrial Fibrillation, Calcium, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Cyclic AMP Response Element Modulator, Disease Models, Animal, Mice, Transgenic, Myocytes, Cardiac, RNA, Messenger, Ryanodine Receptor Calcium Release Channel, Sarcoplasmic Reticulum, NFATC Transcription Factors, Atrial fibrillation, Atrial remodelling, Calcium handling, NFAT, RASEF

Abstract

AIMS: Abnormal intracellular calcium (Ca2+) handling contributes to the progressive nature of atrial fibrillation (AF), the most common sustained cardiac arrhythmia. Evidence in mouse models suggests that activation of the nuclear factor of activated T-cell (NFAT) signalling pathway contributes to atrial remodelling. Our aim was to determine the role of NFATc2 in AF in humans and mouse models.

METHODS AND RESULTS: Expression levels of NFATc1-c4 isoforms were assessed by quantitative reverse transcription-polymerase chain reaction in right atrial appendages from patients with chronic AF (cAF). NFATc1 and NFATc2 mRNA levels were elevated in cAF patients compared with those in normal sinus rhythm (NSR). Western blotting revealed increased cytosolic and nuclear levels of NFATc2 in AF patients. Similar findings were obtained in CREM-IbΔC-X transgenic (CREM) mice, a model of progressive AF. Telemetry ECG recordings revealed age-dependent spontaneous AF in CREM mice, which was prevented by NFATc2 knockout in CREM:NFATc2-/- mice. Programmed electrical stimulation revealed that CREM:NFATc2-/- mice lacked an AF substrate. Morphometric analysis and histology revealed increased atrial weight and atrial fibrosis in CREM mice compared with wild-type controls, which was reversed in CREM:NFATc2-/- mice. Confocal microscopy showed an increased Ca2+ spark frequency despite a reduced sarcoplasmic reticulum (SR) Ca2+ load in CREM mice compared with controls, whereas these abnormalities were normalized in CREM:NFATc2-/- mice. Western blotting revealed that genetic inhibition of Ca2+/calmodulin-dependent protein kinase II-mediated phosphorylation of S2814 on ryanodine receptor type 2 (RyR2) in CREM:RyR2-S2814A mice suppressed NFATc2 activation observed in CREM mice, suggesting that NFATc2 is activated by excessive SR Ca2+ leak via RyR2. Finally, chromatin immunoprecipitation sequencing from AF patients identified Ras and EF-hand domain-containing protein (Rasef) as a direct target of NFATc2-mediated transcription.

CONCLUSION: Our findings reveal activation of the NFAT signalling pathway in patients of Chinese and European descent. NFATc2 knockout prevents the progression of AF in the CREM mouse model.

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