C-Terminal Binding Protein 2 Emerges as a Critical Player Linking Metabolic Imbalance to the Pathogenesis of Obesity.

Metabolism is one of the vital functions of cells and living organisms, and the systems to sense and respond to the metabolic alterations play pivotal roles in a plethora of biological processes, including cell proliferative activities, immune cell functions, aging processes, and neuronal functions. Recently, we have reported that a transcriptional cofactor, C-terminal binding protein 2 (CtBP2), serves as a critical metabolite sensor in this context. CtBP2 has a structural pocket called Rossmann fold to accommodate metabolites, and it has been reported to be activated upon binding to NADH/NAD＋. Owing to its preferential binding affinity for NADH compared with NAD＋, increased glycolysis activates CtBP2 by regenerating NADH from NAD＋. Furthermore, we recently reported that fatty acyl-CoAs, metabolites accumulated under the condition of lipid overload, as represented by obesity, can inactivate CtBP2. These observations suggest that CtBP2 monitors not only redox state but also energy substrate preference in the maintenance of metabolic homeostasis. In line with these metabolite-sensing capabilities, CtBP2 is activated in healthy subjects to protect against metabolic disturbances, whereas inactivation of CtBP2 in obesity contributes to the pathogeneses of obesity.This metabolic system orchestrated by CtBP2 can provide a novel framework for understanding how cells maintain their homeostasis through coordination of metabolism, and CtBP2 incapacitation can be a critical point of the obesogenic cascade.

MicroRNA-21 is associated with fibrosis in a rat model of nonalcoholic steatohepatitis and serves as a plasma biomarker for fibrotic liver disease.

Evidence indicates that hepatic fibrosis is the initial lesion of cirrhosis or hepatocellular carcinoma in diseases such as nonalcoholic steatohepatitis (NASH). To induce NASH, we fed rats a choline-deficient and iron-supplemented L-amino acid-defined (CDAA) diet. Histopathological examination revealed that fibrosis appeared from week 4 and progressed to bridging fibrosis from week 12. Using qRT-PCR assays, we detected increased expression of miR-21, Mmp-9, and Timp-1 in liver that peaked during week 4, when fibrosis was first detected. The expression pattern of miR-21 in plasma paralleled that in liver. Fibrosis tended to be resolved within 12 weeks of a recovery period after 12 weeks of feeding, and the expression of miR-21, Timp-1, and Mmp-9 decreased in liver. Comprehensive analyses of miRNA and mRNA expression in the liver using samples acquired at week 4 detected 16 miRNAs and 11 mRNAs that are mutually-interacting fibrosis-related factors. We therefore conclude that miR-21 was closely associated with fibrosis in a rat model of NASH and has potential as a plasma biomarker for hepatic fibrosis.