Objective: Heart failure (HF) causes structural and functional changes in the heart, with the pyroptosis-mediated inflammatory response as the core link in HF pathogenesis. E3 ubiquitin ligases participate in cardiovascular disease progression. Here, we explored the underlying molecular mechanisms of E3 ubiquitin ligase Smurf1 in governing HF.
Methods: HF rat/H9C2 cell models were established by doxorubicin intraperitoneal injections/hypoxia-reoxygenation (H/R), and treated with Smurf1 siRNA and oe-TRIB2 lentivirus plasmids or the NF-κB pathway inhibitor PDTC/si-smurf1, si-TRIB2, protease inhibitor MG132, or lysosomal inhibitor NH4Cl. The cardiac function/cardiac tissue pathological changes/fibrosis in HF rats were evaluated by echocardiography/H&E and Masson staining. GSDMD-N expression was determined by immunohistochemistry. Cell viability/lactate dehydrogenase (LDH) activity/IL-1β and IL-18 levels were measured by CCK-8/LDH kit/ELISA. The interaction between TRIB2 and Smurf1/TRIB2 ubiquitination levels was assessed by co-immunoprecipitation assay. The expression levels of Smurf1 and TRIB2 messenger RNA (mRNA) were determined by RT-qPCR. Levels of Smurf1/TRIB2/the NF-κB pathway-related factors/pyroptosis-related factors and TRIB2 mRNA were determined by Western blot/RT-qPCR.
Results: Smurf1 was highly expressed in H/R-induced H9C2 cells/HF rats, while its knockdown up-regulated TRIB2 and repressed the NF-κB pathway, reduced cardiomyocyte pyroptosis, and attenuated HF. Mechanistically, Smurf1 promoted TRIB2 degradation through an ubiquitin-dependent manner and activated the NF-κB pathway under H/R conditions. TRIB2 silencing annulled Smurf1 knockdown-regulated NF-κB pathway and cardiomyocyte pyroptosis. TRIB2 overexpression inactivated the NF-κB pathway and reduced cardiomyocyte pyroptosis, thus retarding HF.
Conclusion: Smurf1 was highly expressed in HF rats, which promoted TRIB2 ubiquitination degradation and activated the NF-κB pathway, thereby promoting cardiomyocyte pyroptosis in HF rats.
Keywords: NF-κB; Smurf1; TRIB2; heart failure; pyroptosis; ubiquitination.
Cardiomyocyte pyroptosis underlies the fundamental cause of heart failure (HF). E3 ubiquitin ligases are involved in cardiomyocyte pyroptosis. Here, we explored the underlying molecular mechanisms of E3 ubiquitin ligase Smurf1 in HF. HF rat and H9C2 cell models were established by doxorubicin intraperitoneal injections and hypoxia-reoxygenation (H/R), respectively. HF rats were treated with Smurf1 siRNA, oe-TRIB2, TRIB2 siRNA lentiviral plasmids, and the NF-κB pathway inhibitor PDTC. H9C2 cells were treated with si-smurf1, si-TRIB2, protease inhibitor MG132, and lysosomal inhibitor NH4Cl, respectively. The cardiac function and myocardial tissue damage in HF rats, GSDMD-N expression, cell viability, lactate dehydrogenase (LDH) activity, IL-1β and IL-18 levels, TRIB2-Smurf1 interaction, and TRIB2 ubiquitination were assessed. Smurf1 was up-regulated in H/R-induced H9C2 cells and HF rats, while its knockdown repressed the NF-κB pathway, reduced cardiomyocyte pyroptosis, and attenuated HF. Smurf1 promoted TRIB2 degradation in an ubiquitin-dependent manner and activated the NF-κB pathway under H/R conditions. TRIB2 silencing annulled Smurf1 knockdown-regulated NF-κB pathway and cardiomyocyte pyroptosis. In vivo experiments verified that TRIB2 inhibited the NF-κB pathway and rat myocardial pyroptosis, thus improving HF. Collectively, Smurf1 was up-regulated in HF rats, which promoted TRIB2 ubiquitination degradation and activated the NF-κB pathway, thereby promoting cardiomyocyte pyroptosis in HF rats.