Pregnancy-induced physiological hypertrophic preconditioning attenuates pathological myocardial hypertrophy by activation of FoxO3a

QRICH1 regulates ATF6 transcription to affect pathological cardiac hypertrophy progression

BACKGROUND

Many studies have shown that pathological cardiac hypertrophy is associated with active endoplasmic reticulum (ER) stress. Glutamine-rich protein 1 (QRICH1), as a transcriptional regulator, belongs to the caspase recruitment domain (CARD)-containing gene family. QRICH1 has been shown to influence the outcomes of endoplasmic reticulum stress by regulating the transcription of proteostasis-related genes. In this study, we explored the role of QRICH1 in pathological cardiac hypertrophy.

METHODS

We observed an increased expression of QRICH1 in the hearts of humans and mice with left ventricular hypertrophy (LVH). To assess the functional impact in this context, we employed gain- and loss-of-function approaches, using AAV9 injections to establish cardiac-specific QRICH1 knockdown or overexpression models in transverse aortic constriction (TAC) or isoproterenol (ISO)-induced cardiac hypertrophy.

RESULTS

Our data indicated that cardiomyocyte-specific knockdown of QRICH1 alleviated the hypertrophic phenotype in response to TAC or ISO injection. However, overexpression of QRICH1 exacerbated cardiac hypertrophy, remodeling, dysfunction, cell apoptosis, and inflammatory responses. Mechanistically, we demonstrated that ATF6 was significantly enriched by QRICH1 in cardiomyocytes treated with ISO using RNA-seq combined with CUT&TAG analysis. ChIP-qPCR and luciferase assays further confirmed that ATF6 is a target gene of QRICH1 in cardiomyocytes under growth stimulation. Knockdown of QRICH1 in cardiomyocytes blocked ISO-mediated induction of ATF6, activation of mTORC1, and cellular growth. And all of the above was restored by the overexpression of ATF6.

CONCLUSIONS

QRICH1 plays a pivotal role in cardiac hypertrophy by regulating ATF6, and QRICH1 may be a potential new therapeutic target for pathological cardiac hypertrophy.

EEPD1 attenuates radiation-induced cardiac hypertrophy and apoptosis by degrading FOXO3A in cardiomyocytes

Radiation-induced heart disease (RIHD) is a severe delayed complication of thoracic irradiation (IR). Endonuclease/exonuclease/phosphatase family domain-containing 1 ( EEPD1) plays an important role in DNA damage repair, but its role in RIHD is less known. In this study, EEPD1 global knockout mice, C57BL/6J mice, and C57BL/6J mice overexpressing EEPD1 are treated with radiation at a total dose of 20 Gy or 0 Gy. After 9 weeks, echocardiography is used to assess cardiac hypertrophy and apoptosis. The results show that EEPD1 deletion exacerbates radiation-induced cardiac hypertrophy and apoptosis, while EEPD1 overexpression has the opposite effect. Further mechanistic investigations reveal that EEPD1 interacts with FOXO3A and destabilizes it by catalyzing its deubiquitination. Inhibition of FOXO3A ameliorates cardiac hypertrophy and apoptosis after EEPD1 knockdown. Thus, EEPD1 protects against radiation-induced cardiac hypertrophy and apoptosis via destabilization of FOXO3A, which may offer new insight into therapeutic strategies for RIHD.

Inhibition of miR-146b-5p alleviates isoprenaline-induced cardiac hypertrophy via regulating DFCP1

Pathological cardiac hypertrophy often precedes heart failure due to various stimuli, yet effective clinical interventions remain limited. Recently, microRNAs (miRNAs) have been identified as critical regulators of cardiovascular development. In this study, we investigated the role of miR-146b-5p and its underlying mechanisms of action in cardiac hypertrophy. Isoprenaline (ISO) treatment induced significant hypertrophy and markedly enhanced the expression of miR-146b-5p in cultured neonatal rat cardiomyocytes and hearts of C57BL/6 mice. Transfection with the miR-146b-5p mimic led to cardiomyocyte hypertrophy accompanied by autophagy inhibition. Conversely, miR-146b-5p inhibition significantly alleviated ISO-induced autophagy depression, thereby mitigating cardiac hypertrophy both in vitro and in vivo. Our results showed that the autophagy-related mediator double FYVE domain-containing protein 1 (DFCP1) is a target of miR-146b-5p. MiR-146b-5p blocked autophagic flux in cardiomyocytes by suppressing DFCP1, thus contributing to hypertrophy. These findings revealed that miR-146b-5p is a potential regulator of autophagy associated with the onset of cardiac hypertrophy, suggesting a possible therapeutic strategy involving the inhibition of miR-146b-5p.