FTO-Dependent N ⁶ -Methyladenosine Regulates Cardiac Function During Remodeling and Repair

Abstract

-Despite its functional importance in various fundamental bioprocesses, the studies of N6-methyladenosine (m6A) in the heart are lacking. Here we show that, fat mass and obesity-associated (FTO), an m6A demethylase, plays a critical role in cardiac contractile function during homeostasis, remodeling and regeneration. -We used clinical human samples, preclinical pig and mouse models and primary cardiomyocyte cell cultures to study the functional role of m6A and FTO in the heart and in cardiomyocytes. We modulated expression of FTO using AAV9 (in vivo), adenovirus (both in vivo and in vitro) and siRNAs (in vitro) to study its function in regulating cardiomyocyte m6A, calcium dynamics and contractility and cardiac function post-ischemia. We performed methylated (m6A) RNA immunoprecipitation sequencing (MeRIP-seq) to map transcriptome-wide m6A, and MeRIP qPCR assays to map and validate m6A in individual transcripts, in healthy and failing hearts and myocytes. -We discovered that FTO has decreased expression in failing mammalian hearts and hypoxic cardiomyocytes, thereby increasing m6A in RNA and decreasing cardiomyocyte contractile function. Improving expression of FTO in failing mouse hearts attenuated the ischemia-induced increase in m6A and decrease in cardiac contractile function. This is carried out by the demethylation activity of FTO, which selectively demethylates cardiac contractile transcripts, thus preventing their degradation and improving their protein expression under ischemia. Additionally, we demonstrate that FTO overexpression in mouse models of MI decreased fibrosis and enhanced angiogenesis. -Collectively, our study demonstrates the functional importance of FTO-dependent cardiac m6A methylome in cardiac contraction during heart failure and provides a novel mechanistic insight into the therapeutic mechanisms of FTO.

Changes in m6A RNA methylation contribute to heart failure progression by modulating translation

“…Our study, showing differential m6A methylation in cardiac tissue in case of heart failure, is in agreement with recent reports . Mathiyalagan et al .…”

“…Our study, showing differential m6A methylation in cardiac tissue in case of heart failure, is in agreement with recent reports . Mathiyalagan et al . showed that m6A methylation is involved in the regeneration of the infarct/peri‐infarction area, whereas Dorn et al .…”

“…At present, there is only one recent study which reported a role for m6A in the peri‐infarct zone after myocardial infarction . In our study, we consequently applied transcriptome‐wide approaches and defined changes in m6A in mouse and human heart failure development.…”

A role for m6A RNA methylation in heart failure development?

“…These results are novel and support an important role of epigenetics mechanisms in general and m6A RNA methylation in particular in the development of heart failure. This is in line with recent landmark studies revealing a role for m6A status in cardiac homeostasis and various cardiovascular disorders and repair processes . Although both the current study, and the study by Mathiyalagan et al .…”

“…This is in line with recent landmark studies revealing a role for m6A status in cardiac homeostasis and various cardiovascular disorders and repair processes . Although both the current study, and the study by Mathiyalagan et al . show changes in global changes in the m6A landscape and in cardiac protein synthesis during heart failure, different mechanisms for the potential functionality of m6A are reported.…”