Dual effects of the small-conductance Ca2+-activated K+ current on human atrial electrophysiology and Ca2+-driven arrhythmogenesis: an in silico study

ROS in diabetic atria regulate SK2 degradation by Atrogin-1 through the NF-κB signaling pathway

One of the independent risk factors for atrial fibrillation is diabetes mellitus (DM); however, the underlying mechanisms causing atrial fibrillation in DM are unknown. The underlying mechanism of Atrogin-1-mediated SK2 degradation and associated signaling pathways are unclear. The aim of this study was to elucidate the relationship among reactive oxygen species (ROS), the NF-κB signaling pathway, and Atrogin-1 protein expression in the atrial myocardia of DM mice. We found that SK2 expression was downregulated comitant with increased ROS generation and enhanced NF-κB signaling activation in the atrial cardiomyocytes of DM mice. These observations were mimicked by exogenously applicating H2O2 and by high glucose culture conditions in HL-1 cells. Inhibition of ROS production by diphenyleneiodonium chloride or silencing of NF-κB by siRNA decreased the protein expression of NF-κB and Atrogin-1 and increased that of SK2 in HL-1 cells with high glucose culture. Moreover, chromatin immunoprecipitation assay demonstrated that NF-κB/p65 directly binds to the promoter of the FBXO32 gene (encoding Atrogin-1), regulating the FBXO32 transcription. Finally, we evaluated the therapeutic effects of curcumin, known as a NF-κB inhibitor, on Atrogin-1 and SK2 expression in DM mice and confirmed that oral administration of curcumin for 4 weeks significantly suppressed Atrogin-1 expression and protected SK2 expression against hyperglycemia. In summary, the results from this study indicated that the ROS/NF-κB signaling pathway participates in Atrogin-1-mediated SK2 regulation in the atria of streptozotocin-induced DM mice.

Bibliometric analysis of atrial fibrillation and ion channels

Atrial fibrillation (AF) is a common clinical malignant arrhythmia with an increasing global incidence. Ion channel dysfunction is an important mechanism in the development of AF. In this study, we used bibliometrics to analyze the studies of ion channels and AF, aiming to provide inspiration and reference for researchers. A total of 3179 literature citations were obtained from Web of Science core databases. Analysis software included Excel 2019, VOSviewer 1.6.16, and CiteSpace 5.7.R2. This field of research has been growing since 1985. The most active country is the United States. The University of Montreal is the most important research institution. The journal Cardiovascular Research has published the largest number of articles in this field. Stanley Nattel and Dobromir Dobrev are the most frequently cited authors. The most cited literature was published in Nature and Science. Cardiac electrophysiology, gene expression, pathogenesis of AF, and AF prevention and treatment are the hot topics for this field research. Cardiac fibrillation and catheter ablation may be future research hotspots in this field.