EP300 confers protection against acute pancreatitis via acetylating HSF1 and promoting PRKN-mediated mitophagy in pancreatic acinar cells.

BACKGROUND: Acute pancreatitis (AP) is a severe inflammatory disorder characterized by pancreatic self-digestion, often progressing to systemic inflammation. Despite advances in understanding its pathogenesis, effective therapeutic strategies remain limited. Heat shock factor 1 (HSF1), a critical transcription factor that maintains cellular homeostasis and regulates the stress response, is downregulated in the pancreas of L-arginine-induced AP mice. However, its role and regulatory mechanisms in the pathogenesis of AP remain unclear. This study aims to elucidate the molecular function and mechanisms of HSF1 in AP, focusing on its regulation by E1A binding protein p300 (EP300) and the downstream effects on mitophagy and inflammation. METHODS: Two distinct mouse models of AP were established using L-arginine and cerulein. Pancreatic acinar cells (AR42J) were used to study the effects of HSF1 and parkin RBR E3 ubiquitin protein ligase (PRKN) on mitophagy and inflammation. The expression and regulation between HSF1, PRKN, and EP300 were assessed using genetic and pharmacological approaches. RESULTS: HSF1 deficiency exacerbates AP severity in two distinct mouse models, with increased mortality, pancreatic necrosis, and systemic inflammation. Mechanistically, HSF1 directly binds to the promoter of PRKN, enhancing its transcriptional activity. Thus, HSF1 alleviates the inflammatory response in pancreatic acinar cells during AP by promoting PRKN-mediated mitophagy, reducing ROS production, and inhibiting NLRP3 inflammasome activation. HSF1 expression is downregulated in pancreatic acinar cells due to decreased acetylation by EP300, leading to proteasomal degradation and impaired mitophagy. Pharmacological activation of EP300 (e.g., CTB) restores HSF1 expression, enhances mitophagy, and attenuates inflammation in both in vivo and in vitro settings. CONCLUSION: These findings highlight the critical role of EP300 in regulating HSF1 acetylation and stability, which in turn modulates mitophagy and pyroptosis in AP. Targeting EP300 and its downstream pathways, such as HSF1-PRKN axis, may offer novel therapeutic strategies for AP.