Aberration of CA3 functionally mediates the pathogenesis of Cardiomyocyte hypertrophy in a miR-138-5p dependent manner.

Cardiomyocyte hypertrophy (CDH) is a critical factor in heart disease, leading to heart failure and increased mortality. Despite extensive research, the precise molecular mechanisms underlying CDH remain unclear. In our study, we conducted total RNA sequencing on blood-derived exosomes from 11 CDH patients and 8 healthy donors. This analysis identified differentially expressed genes (DEGs), which we further validated using real-time qPCR and ROC analysis to demonstrate their diagnostic potential in clinical samples. To explore the functional role of CA3 in CDH, we manipulated its expression using the AAV9 vector in TAC (transverse aortic constriction) rat models(N = 6). We observed a significant increase in CA3 expression in both the blood of CDH patients and TAC rat models. Knockdown of Ca3 using the AAV9 vector resulted in improved cardiac function in TAC rats (N = 6), as evidenced by a ∼30 % reduction in LVEF% (left ventricular ejection fraction) and LVFS% (left ventricular fractional shortening) compared to Sham-operated controls. Additionally, LV (left ventricular) mass and the HW/BW (heart weight to body weight ratio) were significantly higher in the TAC groups. Mechanistically, we identified miR-138-5p as a direct regulator of CA3 through the StarBase bioinformatics tool. This interaction was experimentally validated using a dual-luciferase reporter assay and real-time qPCR. We found that miR-138-5p expression was down-regulated in both CDH patients and TAC rat models. Restoration of miR-138-5p expression mitigated the phenotypes induced by Ca3 overexpression. Our findings reveal a novel miR-138-5p/CA3 axis involved in the pathogenesis of CDH, suggesting potential therapeutic avenues for this heart disease.