Gene Therapy With the N-Terminus of Junctophilin-2 Improves Heart Failure in Mice

Abstract

Background: Transcriptional remodeling is known to contribute to heart failure (HF). Targeting stress-dependent gene expression mechanisms may represent a clinically relevant gene therapy option. We recently uncovered a salutary mechanism in the heart whereby JP2 (junctophilin-2), an essential component of the excitation-contraction coupling apparatus, is site-specifically cleaved and releases an N-terminal fragment (JP2NT [N-terminal fragment of JP2]) that translocates into the nucleus and functions as a transcriptional repressor of HF-related genes. This study aims to determine whether JP2NT can be leveraged by gene therapy techniques for attenuating HF progression in a preclinical pressure overload model. Methods: We intraventricularly injected adeno-associated virus (AAV) (2/9) vectors expressing eGFP (enhanced green fluorescent protein), JP2NT, or DNA-binding deficient JP2NT (JP2NT ΔbNLS/ARR ) into neonatal mice and induced cardiac stress by transaortic constriction (TAC) 9 weeks later. We also treated mice with established moderate HF from TAC stress with either AAV-JP2NT or AAV-eGFP. RNA-sequencing analysis was used to reveal changes in hypertrophic and HF-related gene transcription by JP2NT gene therapy after TAC. Echocardiography, confocal imaging, and histology were performed to evaluate heart function and pathological myocardial remodeling following stress. Results: Mice preinjected with AAV-JP2NT exhibited ameliorated cardiac remodeling following TAC. The JP2NT DNA-binding domain is required for cardioprotection as its deletion within the AAV-JP2NT vector prevented improvement in TAC-induced cardiac dysfunction. Functional and histological data suggest that JP2NT gene therapy after the onset of cardiac dysfunction is effective at slowing the progression of HF. RNA-sequencing analysis further revealed a broad reversal of hypertrophic and HF-related gene transcription by JP2NT overexpression after TAC. Conclusions: Our prevention- and intervention-based approaches here demonstrated that AAV-mediated delivery of JP2NT into the myocardium can attenuate stress-induced transcriptional remodeling and the development of HF when administered either before or after cardiac stress initiation. Our data indicate that JP2NT gene therapy holds great potential as a novel therapeutic for treating hypertrophy and HF.

Junctophilin-2 promotes cardiomyocyte survival by blocking MURF1-mediated Junctin ubiquitination and proteasome-dependentdegradation

“…Thus, the current study reveals an unappreciated role of JPH2 in preventing cardiomyocyte apoptosis under stress; and our data together with previous findings suggest that targeting JPH2 may be a useful therapeutic strategy to reduce cardiac pathology under stress. Indeed, transgenic over-expressionof JPH2 or its N-terminus,and gene therapy with its N-terminus attenuate myocardial remodeling and dysfunction in pre-clinical mouse models of heart failure 12, 16, 44 .…”

AAV-mediated gene therapy: Advancing cardiovascular disease treatment

“…While in CUPID phase 1/2a clinical trial, the safety of AAV1/SERCA2a for advanced HF was confirmed to be good, and the body (81). A recent study demonstrated that AAV-JP2NT entry into the myocardium attenuated HF development and stressinduced transcriptional remodeling (110).…”

Junctophillin-2: Coupling Hopes for Cardiac Gene Therapy to Gene Transcription

“…In this issue, Wang et al 6 describe an approach that may bridge the two approaches through the singular behavior of the structural protein JPH-2 (junctophillin 2).…”

“…Wang et al 6 have demonstrated that mice overexpressing JPH-2NT have a significantly milder cardiac phenotype following the induction of cardiac hypertrophy following transverse aortic constriction (TAC). The hearts of mice overexpressing JPH-2NT display much less fibrosis and a preserved cellular TAT network.…”