Epitranscriptomic regulation in fasting hearts: implications for cardiac health

ABSTRACT

Cardiac tolerance to ischaemia can be increased by dietary interventions such as fasting, which is associated with significant changes in myocardial gene expression. Among the possible mechanisms of how gene expression may be altered are epigenetic modifications of RNA – epitranscriptomics. N⁶-methyladenosine (m⁶A) and N⁶,2’-O-dimethyladenosine (m⁶Am) are two of the most prevalent modifications in mRNA. These methylations are reversible and regulated by proteins called writers, erasers, readers, and m⁶A-repelled proteins. We analysed 33 of these epitranscriptomic regulators in rat hearts after cardioprotective 3-day fasting using RT-qPCR, Western blot, and targeted proteomic analysis. We found that the most of these regulators were changed on mRNA or protein levels in fasting hearts, including up-regulation of both demethylases – FTO and ALKBH5. In accordance, decreased methylation (m⁶A+m⁶Am) levels were detected in cardiac total RNA after fasting. We also identified altered methylation levels in Nox4 and Hdac1 transcripts, both of which play a role in the cytoprotective action of ketone bodies produced during fasting. Furthermore, we investigated the impact of inhibiting demethylases ALKBH5 and FTO in adult rat primary cardiomyocytes (AVCMs). Our findings indicate that inhibiting these demethylases reduced the hypoxic tolerance of AVCMs isolated from fasting rats. This study showed that the complex epitranscriptomic machinery around m⁶A and m⁶Am modifications is regulated in the fasting hearts and might play an important role in cardiac adaptation to fasting, a well-known cardioprotective intervention.

KEYWORDS:

• Fasting
• heart
• epitranscriptomics
• m⁶A
• m⁶Am
• FTO
• ALKBH5

Acknowledgments

The authors would like to acknowledge the Proteomics Core Facility (proteomics.fgu.cas.cz) at the Institute of Physiology of the Czech Academy of Sciences and Marek Vrbacky Ph.D. for proteomic analysis; and the Metabolomics Core Facility (metabolomics.fgu.cas.cz) at the Institute of Physiology of the Czech Academy of Sciences and Tomas Cajka Ph.D. for metabolomics and lipidomics profiling. Figures were created with BioRender.com.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Conceptualization: D.B., and M.H.; Formal Analysis: D.B., and M.H.; Funding acquisition: D.B., F.K., and M.H.; Investigation: D.B., K.H., J.H., F.K. and M.H.; Methodology: D.B., K.H., J.H., F.K., and M.H.; Project administration: D.B., and M.H.; Resources: M.O., M.K.; Supervision: F.K., and M.H.; Visualization: D.B., and M.H.; Writing – original draft: D.B.; Writing – review & editing: K.H., J.H., F.K., M.O., M.K., and M.H. All authors read and approved the final submitted manuscript.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15476286.2024.2307732

Additional information

Funding

This work was supported by the Czech Science Foundation under Grant [1904790Y] to M.H.; the Charles University Grant Agency under Grant (GA UK 668220) to D.B.; and the project National Institute for Research of Metabolic and Cardiovascular Diseases [Programme EXCELES, ID Project No. LX22NPO5104] - Funded by the European Union – Next Generation EU.