Exploring the mechanisms of glycolytic genes involvement in pulmonary arterial hypertension through integrative bioinformatics analysis.

The purpose of this study was to identify the mechanisms underlying the involvement of glycolytic genes in pulmonary arterial hypertension (PAH). This study involved downloading 3 datasets from the GEO database at the National Center for Biotechnology Information. The datasets were processed to obtain expression matrices for analysis. Genes involved in glycolysis-related pathways were obtained, and genes related to glycolysis were selected based on significant differences in expression. Gene Ontology functional annotation analysis, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and GSEA enrichment analysis were performed on the DEGs. Combining LASSO regression with SVM-RFE machine learning technology, a PAH risk prediction model based on glycolysis related gene expression was constructed, and CIBERSORTx technology was used to analyse the immune cell composition of PAH patients. Gene enrichment analysis revealed that the DEGs work synergistically across multiple biological pathways. A total of 6 key glycolysis-related genes were selected using LASSO regression and SVM. A bar plot was constructed to evaluate the weights of the key genes and predict the risk of PAH. The clinical application value and predictive accuracy of the model were assessed. Immunological feature analysis revealed significant correlations between key glycolysis-related genes and the abundances of different immune cell types. The glycolysis genes (ACSS2, ALAS2, ALDH3A1, ADOC3, NT5E, and TALDO1) identified in this study play important roles in the development of pulmonary arterial hypertension, providing new evidence for the involvement of glycolysis in PAH.

Exchange proteins directly activated by cAMP mediate cardiac repolarization and arrhythmogenesis during chronic heart failure.

Most sudden cardiac death in chronic heart failure (CHF) is caused by malignant ventricular arrhythmia (VA); however, the molecular mechanism remains unclear. This study aims to explore the effect of exchange proteins directly activated by cAMP (Epac) on VA in CHF and the potential molecular mechanism. Transaortic constriction was performed to prepare CHF guinea pigs. Epac activation model was obtained with 8-pCPT administration. Programmed electrical stimulation (PES) was performed to detect effective refractory period (ERP) or induce VA. Isolated adult cardiomyocytes were treated with 8-pCPT and (or) the Epac inhibitor. Cellular electrophysiology was examined by whole-cell patch clamp. With Epac activation, corrected QT duration was lengthened by 12.6%. The 8-pCPT increased action potential duration (APD) (APD50: 236.9 ± 18.07 ms vs. 328.8 ± 11.27 ms, p < 0.05; APD90: 264.6 ± 18.22 ms vs. 388.6 ± 6.47 ms, p < 0.05) and decreased rapid delayed rectifier potassium (IKr) current (tail current density: 1.1 ± 0.08 pA/pF vs. 0.7 ± 0.03 pA/pF, p < 0.05). PES induced more malignant arrhythmias in the 8-pCPT group than in the control group (3/4 vs. 0/8, p < 0.05). The selective Epac1 inhibitor CE3F4 rescued the drop in IKr after 8-pCPT stimulation (tail current density: 0.5 ± 0.02 pA/pF vs. 0.6 ± 0.03 pA/pF, p < 0.05). In conclusion, Epac1 regulates IKr, APD, and ERP in guinea pigs, which could contribute to the proarrhythmic effect of Epac1 in CHF.

ß-Arrestin2 regulates the rapid component of delayed rectifier K+ currents and cardiac action potential of guinea pig cardiomyocytes after adrenergic stimulation.

A decrease in the rapid component of delayed rectifier potassium current (IKr) during chronic heart failure (CHF) prolongs action potential (AP), and plays a key role in the pathogenesis of ventricular arrhythmias. ß-Arrestin2 has been shown to restore the inotropic reserve of ß-adrenergic regulation, but little or nothing is known about its effect on intrinsic channel. This study investigated the role of ß-arrestin2 in the regulation of cardiac hERG/IKr potassium channel and AP during chronic adrenergic stimulation. Single left ventricular myocytes were isolated from guinea pig heart, and were transfected with adenovirus encoding ß-arrestin2, or ß-arrestin2 siRNA or an empty adenovirus. Cell cultures containing 10 nM isoproterenol, 1 nM phenylephrine or vehicle alone (control medium) were electro-physiologically examined after 48 h of incubation. Action potential duration at 50 and 90 % of repolarization (APD50 and APD90) were measured using whole-cell patch-clamp recording. Sustained adrenergic stimulation significantly reduced the density of the IKr current (p < 0.001). ß-Arrestin2 expression in cell cultures treated with isoproterenol or phenylephrine was significantly downregulated after adrenergic stimulation (p < 0.001). Overexpression of ß-arrestin2 significantly attenuated isoproterenol or phenylephrine-induced reduction in IKr current. It also prevented the phenylephrine-induced prolongation of AP (p < 0.05 for APD50 and p < 0.001 for APD90), but did not significantly affect AP profile after exposure of the cardiomyocytes to isoproterenol (p > 0.05). Therefore, Increased levels of ß-Arrestin2 weaken dysregulation of IKr current and prevent excessive AP prolongation, making it an effective anti-arrhythmic strategy.