The mitochondrial transmembrane (TMEM) protein family has several essential physiological functions. However, its roles in cardiomyocyte proliferation and cardiac regeneration remain unclear. Here, we detected that TMEM11 inhibits cardiomyocyte proliferation and cardiac regeneration in vitro. TMEM11 deletion enhanced cardiomyocyte proliferation and restored heart function after myocardial injury. In contrast, TMEM11-overexpression inhibited neonatal cardiomyocyte proliferation and regeneration in mouse hearts. TMEM11 directly interacted with METTL1 and enhanced m⁷G methylation of Atf5 mRNA, thereby increasing ATF5 expression. A TMEM11-dependent increase in ATF5 promoted the transcription of Inca1, an inhibitor of cyclin-dependent kinase interacting with cyclin A1, which suppressed cardiomyocyte proliferation. Hence, our findings revealed that TMEM11-mediated m⁷G methylation is involved in the regulation of cardiomyocyte proliferation, and targeting the TMEM11-METTL1-ATF5-INCA1 axis may serve as a novel therapeutic strategy for promoting cardiac repair and regeneration.

Background: The relationship between noncoding RNAs (ncRNAs) and human diseases has been a hot topic of research, but the study of ncRNAs in cardiovascular diseases (CVDs) is still in its infancy. PIWI‐interacting RNA (piRNA), a small ncRNA that binds to the PIWI protein to maintain genome stability by silencing transposons, was widely studied in germ lines and stem cells. In recent years, piRNA has been shown to be involved in key events of multiple CVDs through various epigenetic modifications, revealing the potential value of piRNA as a new biomarker or therapeutic target.Conclusion: This review explores origin, degradation, function, mechanism and important role of piRNA in CVDs, and the promising therapeutic targets of piRNA were summarized. This review provide a new strategy for the treatment of CVDs and lay a theoretical foundation for future research.Key points: piRNA can be used as a potential therapeutic target and biomaker in CVDs. piRNA influences apoptosis, inflammation and angiogenesis by regulating epigenetic modificaions. Critical knowledge gaps remain in the unifying piRNA nomenclature and PIWI‐independent function.

Transfer RNA is a class of non-coding RNA that plays a role in amino acid translocation during protein synthesis. After specific modification, the cleaved fragment is called tRNA-derived small RNA. The advancement of bioinformatics technology has led to an increase in the visibility of small RNA derived from tRNA, and their functions in biological processes are being revealed. These include gene silencing, transcription and translation, epigenetics, and cell death. These properties have led to the implication of tsRNAs in various diseases. Although the current research mainly focuses on the role of tRNA-derived small RNA in cancer, there is mounting evidence that they are also strongly associated with cardiovascular disease, including cardiac hypertrophy, atrial fibrillation, heart failure, and myocarditis. Therefore, the regulatory role of tRNA-derived small RNA in cardiovascular disease will become an emerging therapeutic strategy. This review succinctly summarizes the characteristics, classification, and regulatory effect of tsRNA. By exploring the mechanism of tsRNA, it will provide a new tool for the diagnosis and prognosis of cardiovascular disease.

TRNA-derived small RNAs (tsRNAs) or tRNA-derived fragments (tRFs) are an important class of regulatory molecules whose role in cardiac hypertrophy remains largely unknown. Here, we identified a novel tRF contributing to the regulation of cardiac hypertrophy that we termed CHAtRF (cardiac hypertrophy-associated tRF). The CHAtRF level was increased in mice and in patients with cardiac hypertrophy. CHAtRF deficiency attenuated angiotensin II (AngII)-induced cardiac hypertrophy and restored the heart function, while CHAtRF overexpression enhanced hypertrophic responses. Mechanistically, CHAtRF directly interacts with SRSF5 and blocks SRSF5 to bind with Psmg4 pre-mRNA, which mediates alternative splicing of Psmg4 pre-mRNA and promotes exon 2 skipping of Psmg4. CHAtRF-dependent alternative splicing of Psmg4 inhibits the expression of Psmg4 full-length isoform, resulting in progression of pathological hypertrophy. The ability of CHAtRF to regulate hypertrophy was confirmed in hiPSC-CMs, and CHAtRF serum levels are higher in individuals with myocardial hypertrophy or heart failure. Our findings reveal new insights into the previously unrecognized role of tsRNAs during cardiac hypertrophy, which provide potential novel therapeutic targets for pathological hypertrophy and might serve as potential biomarkers for diagnosing cardiac hypertrophy and heart failure.

PIWI-interacting RNAs (piRNAs) are widely expressed in cardiac tissues and play important roles in cardiac pathophysiology. However, their functions and molecular mechanisms in cardiac remodeling following myocardial infarction (MI) and cardiomyocyte ferroptosis remain largely unknown. Here, we identified a ferroptosis-related piRNA (FERPIR), which inhibits ischemia/reperfusion (I/R) induced myocardial injury, cardiac remodeling and ferroptosis by targeting HNRNPA2B1-dependent regulation of Fis1. FERPIR levels were decreased in hypoxia/reoxygenation (H/R)-exposed cardiomyocytes and I/R-injured mouse hearts. FERPIR prevented I/R-induced acute injury and pathological cardiac remodeling. In vitro, overexpression of FERPIR inhibits H/R-induced ferroptosis. Mechanistically, FERPIR directly bound to HNRNPA2B1 and promoted its stability, which exhibited decreased ferroptosis and improved cardiac function upon I/R injury. Fis1 acted as a downstream regulator of HNRNPA2B1, and FERPIR recruited HNRNPA2B1 to bind to Fis1 mRNA and decreased its stability, thereby inhibiting mitochondrial fission and ferroptosis, which improves cardiac remodeling after myocardial infarction. Our findings reveal that FERPIR prevents myocardial I/R induced injury and pathological cardiac remodeling through the HNPA2B1/Fis1 axis, which provides potential therapeutic targets against cardiac injury caused by cardiomyocyte ferroptosis.