ER stress – Cell Stress

The IRE1α-XBP1s-NFκB axis controls cell survival and epithelial differentiation under osmotic stress through arachidonic acid metabolism activation

Arachidonic acid (AA) metabolism plays a critical role in renal cell osmoadaptation. We recently demonstrated that hypertonicity induces the expression and activation of cytosolic phospholipase A2 (cPLA2). On one hand, AA released by cPLA2 enhances triacylglyceride (TG) synthesis and accumulation. On the other hand, AA is converted into prostaglandins (PG) through cyclooxygenase 2 (COX2) activity. Both processes are required for renal cell survival under osmotic stress. However, the mechanisms by which hypertonicity induces cPLA2 expression remain poorly understood. Given that we previously shown that hypertonicity regulates TG synthesis through the IRE1α-XBP1s branch of the unfolded protein (…)

Macrolide antibiotics activate the integrated stress response and promote tumor proliferation

Macrolide antibiotics are widely used antibacterial agents that are associated with autophagy inhibition. This study aimed to investigate the association between macrolide antibiotics and malignant tumors, as well as the effect on autophagy, reactive oxygen species (ROS) accumulation and integrated stress response (ISR). The meta-analysis indicated a modestly higher risk of cancer in macrolide antibiotic ever-users compared to non-users. Further experiments showed that macrolides block autophagic flux by inhibiting lysosomal acidification. Additionally, azithromycin, a representative macrolide antibiotic, induced the accumulation of ROS, and stimulated the ISR and the activation of transcription factor EB (TFEB) and TFE3 in a ROS-dependent manner. Finally, animal experiments confirmed that azithromycin promoted tumor progression in vivo, which (…)

Foie gras and liver regeneration: a fat dilemma

The liver has a unique ability of regenerating after injuries or partial loss of its mass. The mechanisms responsible for liver regeneration – mostly occurring when the hepatic tissue is damaged or functionally compromised by metabolic stress – have been studied in considerable detail over the last few decades, because this phenomenon has both basic-biology and clinical relevance. More specifically, recent interest has been focusing on the widespread occurrence of abnormal nutritional habits in the Western world that result in an increased prevalence of non-alcoholic fatty liver disease (NAFLD). NAFLD is closely associated with insulin resistance and dyslipidemia, and it represents a major clinical challenge. The disease may progress to steatohepatitis with persistent inflammation and progressive liver damage, both of which will compromise regeneration under conditions of partial hepatectomy in surgical oncology or in liver transplantation procedures. Here, we analyze the impact of ER stress and SIRT1 in lipid metabolism and in fatty liver pathology (…)