Wogonin ameliorates ER stress-associated inflammatory response, apoptotic death and renal fibrosis in a unilateral ureteral obstruction mouse model.

Wogonin, a vital bioactive compound extracted from the medicinal plant, Scutellaria baicalensis, has been wildly used for its potential in mitigating the progression of chronic diseases. Chronic kidney disease (CKD) represents a significant global health challenge due to its high prevalence, morbidity and mortality rates, and associated complications. This study aimed to assess the potential of wogonin in attenuating renal fibrosis and to elucidate the underlying molecular mechanisms using a unilateral ureteral obstruction (UUO) mouse model as a CKD mimic. Male mice, 8 weeks old, underwent orally administrated of either 50 mg/kg/day of wogonin or positive control of 5 mg/kg/day candesartan following UUO surgery. NRK52E cells were exposed to tumor growth factors-beta (TGF-ß) to evaluate the anti-fibrotic effects of wogonin. The results demonstrated that wogonin treatment effectively attenuated TGF-ß-induced fibrosis markers in NRK-52E cells. Additionally, administration of wogonin significantly improved histopathological alterations and downregulated the expression of pro-fibrotic factors (Fibronectin, α-smooth muscle actin, Collagen IV, E-cadherin, and TGF-ß), oxidative stress markers (Catalase, superoxide dismutase 2, NADPH oxidase 4, and thioredoxin reductase 1), inflammatory molecules (Cyclooxygenase-2 and TNF-α), and the infiltration of neutrophils and macrophages in UUO mice. Furthermore, wogonin treatment mitigated endoplasmic reticulum (ER) stress-associated molecular markers (GRP78, GRP94, ATF4, CHOP, and the caspase cascade) and suppressed apoptosis. The findings indicate that wogonin treatment ameliorates key fibrotic aspects of CKD by attenuating ER stress-related apoptosis, inflammation, and oxidative stress, suggesting its potential as a future therapeutic target.

Methylmercury Induces Mitochondria- and Endoplasmic Reticulum Stress-Dependent Pancreatic ß-Cell Apoptosis via an Oxidative Stress-Mediated JNK Signaling Pathway.

Methylmercury (MeHg), a long-lasting organic pollutant, is known to induce cytotoxic effects in mammalian cells. Epidemiological studies have suggested that environmental exposure to MeHg is linked to the development of diabetes mellitus (DM). The exact molecular mechanism of MeHg-induced pancreatic ß-cell cytotoxicity is still unclear. Here, we found that MeHg (1-4 µM) significantly decreased insulin secretion and cell viability in pancreatic ß-cell-derived RIN-m5F cells. A concomitant elevation of mitochondrial-dependent apoptotic events was observed, including decreased mitochondrial membrane potential and increased proapoptotic (Bax, Bak, p53)/antiapoptotic (Bcl-2) mRNA ratio, cytochrome c release, annexin V-Cy3 binding, caspase-3 activity, and caspase-3/-7/-9 activation. Exposure of RIN-m5F cells to MeHg (2 µM) also induced protein expression of endoplasmic reticulum (ER) stress-related signaling molecules, including C/EBP homologous protein (CHOP), X-box binding protein (XBP-1), and caspase-12. Pretreatment with 4-phenylbutyric acid (4-PBA; an ER stress inhibitor) and specific siRNAs for CHOP and XBP-1 significantly inhibited their expression and caspase-3/-12 activation in MeHg-exposed RIN-mF cells. MeHg could also evoke c-Jun N-terminal kinase (JNK) activation and reactive oxygen species (ROS) generation. Antioxidant N-acetylcysteine (NAC; 1mM) or 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox; 100 µM) markedly prevented MeH-induced ROS generation and decreased cell viability in RIN-m5F cells. Furthermore, pretreatment of cells with SP600125 (JNK inhibitor; 10 µM) or NAC (1 mM) or transfection with JNK-specific siRNA obviously attenuated the MeHg-induced JNK phosphorylation, CHOP and XBP-1 protein expression, apoptotic events, and insulin secretion dysfunction. NAC significantly inhibited MeHg-activated JNK signaling, but SP600125 could not effectively reduce MeHg-induced ROS generation. Collectively, these findings demonstrate that the induction of ROS-activated JNK signaling is a crucial mechanism underlying MeHg-induced mitochondria- and ER stress-dependent apoptosis, ultimately leading to ß-cell death.