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Abstract: Background: Both endoplasmic reticulum (ER) stress and autophagy have been shown to display dual roles in cell survival in multiple cell lines. There is a reported but poorly understood link between ER stress, autophagy, and cell death. We hypothesized that autophagy plays a role in ER stress-dependent cell death in rat hepatocytes. Materials and methods: Primary hepatocytes isolated from both lean and obese male Zucker rats were cultured and treated with tunicamycin (TM), tauroursodeoxycholic acid, 3-methyladenine, and wortmannin for 12 h. The ER stress-associated genes glucose-regulated protein 78 and C/EBP homologous protein were examined via quantitative real time polymerase chain reaction. Immunostaining with microtubule-associated protein 1 light chain 3 as well as electron microscopy were used to evaluate autophagy activity. Trypan blue exclusion was used to determine hepatocyte cell viability. Results: In both lean and steatotic hepatocytes, we found that TM induced both C/EBP homologous protein and glucose-regulated protein 78 messenger RNA expression. Cells with increased ER stress were undergoing increased autophagy and had a significant decrease in cell viability. Both tauroursodeoxycholic acid and 3-methyladenine treatments attenuated TM induced ER stress, autophagy, and cell death, whereas wortmannin treatment reduced autophagy and cell death but without changing ER stress. Conclusions: These data suggest that autophagy is a likely downstream mediator of ER stress-induced cell death in rat hepatocytes. Further exploration of the link between autophagy and ER stress in hepatocyte injury will yield important information that may be leveraged for treatment of liver injuries such as ischemia/reperfusion. [Copyright &y& Elsevier]

Hepatic ischemia reperfusion (IR) injury is an important clinical problem complicating liver surgery and transplantation. The pathogenesis underlying reperfusion injury after warm ischemia is complex, encompassing a multitude of different cell types and signalling mechanisms innate and/or mobilized to the liver. Since the author's 2003 review in the Journal, considerable progress has been achieved in enhancing our understanding of some of the pathogenic pathways and crucial mediators of hepatic inflammation such as the heme oxygenase system, CXC chemokines, Toll-like receptors as well as the mode of parenchymal cell death in IR injury. A better appreciation of these mechanisms will accelerate efforts in designing optimal interventions to prevent hepatic IR injury and improve outcomes after liver transplantation. [ABSTRACT FROM AUTHOR]

Liver fibrosis is a consequence of chronic liver injury associated with chronic viral infection, alcohol abuse, and nonalcoholic fatty liver. The evidence from clinical and animal studies indicates that transforming growth factor-β (TGF-β) signaling is associated with the development of liver fibrosis. Krüppel-like factor 10 (KLF10) is a transcription factor that plays a significant role in TGF-β-mediated cell growth, apoptosis, and differentiation. In recent studies, it has been reported to be associated with glucose homeostasis and insulin resistance. In the present study, we investigated the role of KLF10 in the progression of liver disease upon a high-sucrose diet (HSD) in mice. Wild type (WT) and Klf10 knockout (KO) mice were fed either a control chow diet or HSD (50% sucrose) for eight weeks. Klf10 KO mice exhibited significant hepatic steatosis, inflammation, and liver injury upon HSD feeding, whereas the WT mice exhibited mild hepatic steatosis with no apparent liver injury. The livers of HSD-fed Klf10 KO mice demonstrated significantly increased endoplasmic reticulum stress, oxidative stress, and proinflammatory cytokines. Klf10 deletion led to the development of sucrose-induced hepatocyte cell death both in vivo and in vitro. Moreover, it significantly increased fibrogenic gene expression and collagen accumulation in the liver. Increased liver fibrosis was accompanied by increased phosphorylation and nuclear localization of Smad3. Here, we demonstrate that HSD-fed mice develop a severe liver injury in the absence of KLF10 due to the hyperactivation of the endoplasmic reticulum stress response and CCAAT/enhance-binding protein homologous protein (CHOP)-mediated apoptosis of hepatocytes. The current study suggests that KLF10 plays a protective role against the progression of hepatic steatosis into liver fibrosis in a lipogenic state. [ABSTRACT FROM AUTHOR]