The global objectives of this application are: 1) to assist the applicant in the acquisition of research skills that will facilitate his development into an independent investigator, and 2) to examine the role of the liver in lipid-mediated inflammation. Non-alcoholic fatty liver disease (NAFLD) is a burgeoning obesity-related disorder that increases the risk of steatohepatitis and cryptogenic cirrhosis. Elevated serum and hepatic lipids are a characteristic feature of NAFLD and have been implicated in both the local and systemic inflammation present in this disease. CREBh is a recently identified, liver-specific, endoplasmic reticulum- localized transcription factor, which, following proteolytic cleavage, translocates to the nucleus and is required for transcription of the acute phase reactants C-reactive protein and serum amyloid P-component. We have recently demonstrated that long chain fatty acids increase CREBh gene and protein expression, the former via transcriptional mechanisms that are dependent on an intact proteasome and independent of cellular metabolism. Thus, CREBh may represent an important link between elevated lipids, inflammation and metabolic disease. However, the specific mechanism(s) by which fatty acids activate CREBh is unknown. Given that fatty acid metabolism is not required for CREBh induction, the specific target of fatty acids likely include a factor(s) that acts independently of cellular metabolism. Toll-Like Receptors (TLR), in particular TLR4, play a critical role in innate immunity, and can be activated by the lipid component of lipopolysaccharide (LPS). Recent data demonstrate that fatty acid-induced insulin resistance and inflammation in adipocytes, skeletal muscle, and endothelial cells is prevented following inhibition of TLR4 signaling. In the liver, several cell types express TLR4 and/or TLR2, including Kupffer cells, stellate cells and hepatocytes. Recent data suggest that TLR4 signaling plays a pivotal role in hepatic steatosis and liver damage, and preliminary data from our laboratory indicate that TLR4 activation via LPS induces CREBh gene expression in H4IIE liver cells. Thus, we hypothesize that TLR4 mediates fatty acid regulation of CREBh. Experiments in the current proposal are designed to directly test this hypothesis.
| Gentile, Christopher L; Nivala, Angela M; Gonzales, Jon C et al. (2011) Experimental evidence for therapeutic potential of taurine in the treatment of nonalcoholic fatty liver disease. Am J Physiol Regul Integr Comp Physiol 301:R1710-22 |
| Gentile, C L; Wang, D; Pfaffenbach, K T et al. (2010) Fatty acids regulate CREBh via transcriptional mechanisms that are dependent on proteasome activity and insulin. Mol Cell Biochem 344:99-107 |
