SGPP2 Ameliorates Chronic Heart Failure by Attenuating ERS via the SIRT1/AMPK Pathway.

Objective: To investigate the mechanism by which sphingosine-1-phosphatase 2 (SGPP2) modulates endoplasmic reticulum stress (ERS) through the SIRT1/AMPK pathway to improve ischemic cardiomyopathy-induced chronic heart failure (IHF). Methods: Key genes of IHF and ERS were identified through bioinformatics analysis, and significantly associated pathways of the key genes were obtained via single-gene enrichment analysis. In vivo, IHF was induced in Sprague-Dawley (male) rats via ligation of the left anterior descending coronary artery, with cardiac function examined through echocardiography. Myocardial tissue injury and fibrosis were evaluated utilizing hematoxylin-eosin, Masson, and TUNEL staining. Serum levels of NT-proBNP and cTnT were measured via ELISA. SGPP2 protein expression was assessed via immunohistochemistry and Western blotting (WB). In vitro, neonatal rat cardiomyocytes (NRCMs) were isolated and underwent oxygen-glucose deprivation (OGD) to establish an IHF model. SGPP2-overexpressing NRCMs were constructed and treated with the ERS inducer tunicamycin (Tu) or the SIRT1 inhibitor EX527. Cell injury was evaluated using Cell Counting Kit-8 and lactate dehydrogenase release assays, as well as flow cytometry. Endoplasmic reticulum structure was examined by transmission electron microscopy. The endoplasmic reticulum was labeled with the ER-Tracker Red molecular probe. WB was utilized to detect the expression of apoptosis- and ERS-linked proteins, and the activity of the SIRT1/AMPK signaling pathway. Results: Six key genes (CTSK, FURIN, SLC2A1, RSAD2, SGPP2, and STAT3) were identified through bioinformatics analysis, with SGPP2 showing the most significant differential expression. Additionally, SGPP2 was found to be downregulated in IHF. Single-gene enrichment analysis showed that SGPP2 exhibited a significant association with the AMPK signaling pathway. Animal experiments demonstrated that rats with IHF exhibited significantly impaired cardiac function, marked myocardial tissue injury and fibrosis, ERS in myocardial tissue, lowered SGPP2 expression, and decreased SIRT1/AMPK signaling pathway activity. In vitro experiments confirmed that SGPP2 overexpression alleviated OGD-induced cardiomyocyte injury by inhibiting ERS and simultaneously activating the SIRT1/AMPK signaling pathway. Rescue experiments further demonstrated that both Tu and EX527 significantly promoted ERS and cellular injury, thereby counteracting the protective effects of SGPP2. Conclusions: SGPP2 alleviates IHF by inhibiting ERS modulated by the SIRT1/AMPK pathway.