Cardiac α2δ1 C-terminal contributes to left atrial hypertrophy in chronic ischemic heart failure, in association with changes in membrane GluN1 and p-CAMKII/p-HDAC4 signaling.

Left atrial remodeling (LAR) critically contributes to the progression of heart failure (HF) and the development of atrial fibrillation (AF) following myocardial infarction (MI). The protein α2δ1, primarily known for its role in neuropathic pain, is abundantly expressed in atrial tissue, but its involvement in post-MI LAR remains unclear. Here, LAR models were established in rats post-MI, and atrial hypertrophy was induced in HL-1 cells using angiotensin II (AngII). The role of α2δ1 in atrial hypertrophy was examined through treatment with either the α2δ1 inhibitor gabapentin or a C-terminal interfering peptide (α2δ1 CT-pep). A significant upregulation of α2δ1 expression was observed in the left atrium (LA) of MI rats and in AngII-treated HL-1 cells. Western blot analysis revealed increased α2δ1 levels in membrane fractions and decreased levels in the cytoplasmic fractions compared to controls. Both gabapentin and α2δ1 CT-pep treatment significantly reduced HL-1 cell hypertrophy and inhibited CAMKII and HDAC4 phosphorylation. Co-immunoprecipitation assays demonstrated an interaction between α2δ1 and GluN1, which was enhanced by AngII stimulation. Inhibition of α2δ1 attenuated the α2δ1-GluN1 interaction and reduced GluN1 translocation to the plasma membrane. In MI-induced HF rats, gabapentin treatment diminished atrial hypertrophy, suppressed AF inducibility and duration, and decreased membrane-associated α2δ1 and GluN1 levels. These findings suggest that the C-terminal domain of α2δ1 may contribute to left atrial hypertrophy in chronic ischemic heart failure and is associated with altered membrane GluN1 abundance and p-CAMKII/p-HDAC4 signaling. α2δ1 may therefore represent a potential therapeutic target for left atrial remodeling in ischemic heart failure.