Novel Truncated Peptide Derived From circCDYL Exacerbates Cardiac Hypertrophy.

BACKGROUND

Circular RNAs (circRNAs) have been gradually revealed to regulate the progression of heart disease in depth, showing their clinical significance. However, a mass of cardiac circRNAs still has not been functionally characterized. We aimed to explore the potential candidates that are involved in pathological cardiac hypertrophy.

METHODS

Public substantial RNA-sequencing data of cardiac circRNAs were utilized to search the cardiac hypertrophy-related circRNAs. Cardiomyocyte hypertrophy in vitro was induced by Ang II (angiotensin II) treatment. Mice were subjected to Ang II infusion to induce cardiac hypertrophy in vivo. Gain-of-function and loss-of-function assays were conducted to detect the effect of RNAs or proteins in cardiac hypertrophy.

RESULTS

A circRNA derived from the (chromodomain Y-like) gene was screened out and named circCDYL. Our results showed that the expression of circCDYL in primary rat cardiomyocytes was significantly induced by Ang II. Gain-of-function and loss-of-function assays demonstrated that circCDYL effectively promoted cardiomyocyte hypertrophy in vitro. CircCDYL could encode a ≈100-aa truncated CDYL peptide (tCDYL-100), whose sequence highly overlaps that of full-length CDYL. The translation of tCDYL-100 was activated by N6-methylation of circCDYL under prohypertrophic stimulation. tCDYL-100 fulfilled the prohypertrophic function of circCDYL. Mechanistically, tCDYL-100 competed with CDYL for binding REST (RE1-silencing transcription factor) and further disrupted the formation of REST-CDYL-EHMT2 (euchromatic histone-lysine N-methyltransferase 2) transcriptional repression complex, resulting in transcriptional activation of and . Silence of circCDYL in mouse hearts could inhibit Ang II-induced cardiac hypertrophy, while forced expression of tCDYL-100 could cause cardiac hypertrophy.

CONCLUSIONS

In summary, our study uncovered an important circRNA-derived peptide and a regulatory mechanism on transcription mediated by N6-methyladenosine-circRNA-histone methylation in pathological cardiac hypertrophy.