p300 upregulates Ikur in atrial cardiomyocytes through activating NLRP3 inflammasome in hypertension.

Abstract

Background: The nucleotide-binding oligomerization domain [NOD-], leucine-rich repeats [LRR-], and Pyrin domain-containing protein 3 (NLRP3) inflammasome plays an essential role in hypertension-related atrial fibrillation (AF). p300 is involved in cardiovascular inflammation. In this study, we aimed to investigate the role of p300 in NLRP3 inflammasome activation and its subsequent impact on the Ikur current in angiotensin II (Ang II)-induced HL-1 cells and Ang II-infused mice.

Methods: Expression levels of p300, Kv1.5, and NLRP3 in left atrial appendage (LAA) tissues from AF and sinus rhythm (SR) patients were detected by Western blot. A hypertension mouse model was established in p300 knockout (p300-KO) mice via Ang II infusion, and AF incidence was assessed by electrocardiogram (ECG) after rapid atrial pacing. In vitro, the expression level of p300 in HL-1 cells was modulated by adenoviral overexpression, curcumin (an inhibitor of p300) treatment, and smal interfering RNA (siRNA) knockdown. NLRP3 inflammasome activation was evaluated by Western blot and enzyme-linked immunosorbent assay, and electrophysiological properties of HL-1 cells were analyzed using whole-cell patch-clamp recordings. Co-immunoprecipitation assays were performed to investigate the interaction between p300 and nuclear factor kappa B (NF-κB).

Results: The expression levels of p300, Kv1.5, and NLRP3 were found to be significantly higher in the LAA tissue of AF patients compared to SR patients. p300-KO decreased AF incidence in Ang II-infused mice by impairing NLRP3 inflammasome activation. p300-OE facilitated NLRP3 inflammasome activation, which subsequently increased the Ikur density and shortened the action potential duration of HL-1 cells. Both curcumin (p300 inhibitor) and p300-siRNA treatments reversed Ang II-induced atrial electrical remodeling and NLRP3 inflammasome activation. Moreover, co-immunoprecipitation showed that p300 interacts with NF-κB to promote NLRP3 inflammasome activation.

Conclusions: p300 participates in hypertension-induced AF susceptibility by interacting with NF-κB to activate the NLRP3 inflammasome, which subsequently upregulates the transmembrane current of Ikur in atrial cardiomyocytes.