Abstract: BACKGROUND: ABL1 is involved in the regulation of multiple cellular processes, yet its functions within the cardiovascular system remains largely unexplored. In particular, its role in cardiac ischemia/reperfusion injury and necroptosis has not been reported.
OBJECTIVE: To investigate the role of ABL1 in cardiac ischemia/reperfusion injury and myocardial necroptosis, as well as the underlying molecular mechanisms.
METHODS: (1) Animal experiment: C57BL/6J mice were randomly divided into four groups: sham surgery group, ischemia/reperfusion group, ABL1 knockdown + ischemia/reperfusion group, and ABL1 negative control + ischemia/reperfusion group. Lentiviral vectors targeting ABL1 were injected in situ into the myocardium to knock down ABL1 expression. One week later, cardiac ischemia/reperfusion injury was induced in mice via ligation of the left anterior descending coronary artery followed by reperfusion. Protein expression of ABL1 in heart tissue was detected. Cardiac function, myocardial fibrosis, and cardiomyocyte surface area were assessed. (2) Cell experiment: H9c2 cells were divided into four groups: negative control cell line + PBS group, ABL1 knockdown cell line + PBS group, negative control cell line + hydrogen peroxide (H₂O₂) 500 µmol/L group, and ABL1 knockdown cell line + H2O2 500 µmol/L group. Another H9c2 cells were divided into five groups: negative control cell line+PBS group, negative control cell line + H₂O₂ 500 µmol/L group, and ABL1 knockdown cell line + H₂O₂ 500 µmol/L group, ABL1 knockdown cell line + Parkin overexpression adenovirus + H₂O₂ 500 µmol/L group, and ABL1 knockdown cell line + Parkin negative control adenovirus+H₂O₂ 500 µmol/L group. ABL1-knockdown cell lines were established. An oxidative stress model was induced using hydrogen peroxide (H₂O₂). Subsequent changes in cell viability, necroptosis levels, and reactive oxygen species level were evaluated. Mitochondrial membrane potential was detected, and the expression levels of ABL1, Parkin and CypD were measured. Whether ABL1 protein and Parkin form a signaling axis was detected.
RESULTS AND CONCLUSION: (1) ABL1 expression was significantly down-regulated in the mouse model of cardiac ischemia/reperfusion. (2) Knockdown of ABL1 exacerbated ischemia/reperfusion-induced cardiac dysfunction, as evidenced by reduced left ventricular ejection fraction and fractional shortening, along with increased left ventricular end-systolic and end-diastolic diameters. (3) Knockdown of ABL1 promoted ischemia/reperfusion-induced myocardial fibrosis and aggravated ischemia/reperfusion-induced ventricular remodeling. (4) ABL1 expression was significantly downregulated in the cardiomyocyte oxidative stress model. (5) Knockdown of ABL1 exacerbated oxidative stress-induced reductions in cell viability, increases in necroptosis, and reactive oxygen species accumulation. (6) ABL1 regulated mitochondrial membrane permeability, influenced the expression of Parkin and CypD, and modulated cellular oxidative stress levels by targeting Parkin. In conclusion, ABL1 expression is significantly reduced in both in vivo ischemia/reperfusion models and in vitro oxidative stress models. Furthermore, ABL1 knockdown exacerbates cardiac ischemia/reperfusion injury and oxidative stress-induced cardiomyocyte damage by targeting the Parkin-CypD signaling pathway. 

Key words: ABL1, ischemia-reperfusion injury, necroptosis, oxidative stress, mitochondrial membrane permeability, Parkin, CypD