Exploring the Role of Nesprin1 in isoproterenol-induced heart failure: Insights into pathogenesis and therapeutic implications.

OBJECTIVE

This study aimed to investigate the role of Nesprin-1 in the development and progression of isoproterenol (ISO)-induced heart failure (HF) and to elucidate the underlying molecular mechanisms.

METHODS

HF was induced in mice via daily intraperitoneal injections of ISO (5 mg/kg/day) for 24 consecutive days. Cardiac function was evaluated using transthoracic echocardiography to measure diastolic left ventricular diameters (LVDd), systolic left ventricular end diameter (LVDs), ejection fraction (EF), and fractional shortening (FS). The HF model was validated through gross cardiac observation, WGA staining, and Western blot analysis of B-type Natriuretic Peptide (BNP). Histological changes were assessed via H&E staining. Oxidative stress was evaluated by quantifying malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity. The expression and localization of Nesprin-1, Connexin 43 (Cx43), DNA damage markers (53BP1, γH2AX), and epigenetic markers (H3K9me3, H3K27me3) were examined using immunofluorescence and Western blotting. The activation of the ERK signaling pathway was also analyzed.

RESULTS

Compared with the control group, ISO-induced HF mice exhibited significant increases in body/heart weight and cardiomyocyte cross-sectional area, alongside elevated BNP expression (P < 0.01). Echocardiography revealed increased LVDd and LVDs with markedly reduced EF and FS (P < 0.01). Histopathologically, the model group showed disorganized myocardial structures, vascular proliferation, and hemorrhage. Crucially, Nesprin-1 expression was significantly downregulated (P < 0.01), accompanied by abnormal nuclear membrane localization and morphological changes in myocardial cell nuclei. Significant nuclear distortions in the model group included increased area, perimeter, and length-to-diameter ratio alongside reduced roundness. Parallel to these changes, the model group showed increased malondialdehyde levels and decreased superoxide dismutase activity (P < 0.05). Notably, several markers showed highly significant differences (P < 0.01), including the downregulation of Connexin 43 and the upregulation of DNA damage markers γH2AX and 53BP1. Significant epigenetic remodeling, characterized by elevated H3K9me3 and H3K27me3, was also observed. Finally, a marked hyperactivation of the ERK signaling pathway was recorded, also reaching statistical significance at (P < 0.01).

CONCLUSION

Our findings indicate that the downregulation of Nesprin-1 is closely associated with HF pathogenesis. In the ISO-induced HF model, diminished Nesprin-1 expression correlated with disrupted nuclear homeostasis, reduced Cx43 expression, severe oxidative stress, DNA damage accumulation, and epigenetic disturbances, which may be mediated through the abnormal activation of the ERK signaling pathway.