BACKGROUND & AIMS Hyperhomocysteinemia is often associated with liver and metabolic

BACKGROUND & AIMS Hyperhomocysteinemia is often associated with liver and metabolic diseases. and the liver responses to ethanol and homocysteine. SHP inhibits the transcriptional activation of and by FOXA1. gene expression.8 Numerous studies suggest that SHP has pleiotropic roles in the pathology of chronic liver diseases. In lipid metabolism SHP facilitates hepatic lipid accumulation since liver steatosis in leptin deficient mice was abrogated by the deletion of SHP.9 Moreover SHP modulates the transcriptional activity of lipogenic transcription factors peroxisome TNFRSF10D proliferator-activated receptor γ and sterol regulatory element-binding protein-1c.10 On the other hand Shp?/? mice were more sensitive to bile duct ligation-induced cholestatic liver fibrosis.11 12 SHP also has anti-oncogenic properties in the liver via actions on both transcription factors and microRNAs. 13-15 Consistently SHP was significantly downregulated in human hepatocellular carcinoma.16 Despite intensive studies of Hcy metabolism limited information is available regarding transcriptional control of this important physiological process at the molecular level. Such an understanding would facilitate progress towards new therapeutic approaches to treat HHcy caused by alcoholic liver disease and metabolic dysregulation. In the present study we demonstrate that nuclear receptor SHP is usually a new modulator of oscillatory metabolism of homocysteine by suppressing forkhead box A1 (FoxA1)-induced and expression. Nardosinone and studies WT values less than 0.05 were considered to be statistically significant. All data are shown as imply ± standard error of imply (SEM) from impartial experiments. Results and Conversation and and mRNA and protein over a 24h light/dark (LD) (12h/12h) cycle. As expected the mRNA (Fig. 1a middle) and protein (Fig. 1a bottom) expression of Bhmt and Cth were both highly induced in and in and remained comparable in WT and and showed a shift in circadian phase; expression was increased during the light cycle but decreased during the dark cycle in and and in and expression under a physiological condition WT mice were fed 1% cholic acid (CA) diet which is known to induce the endogenous Shp expression or 2% cholestyramine (Chol) diet to interrupt the enterohepatic blood circulation of bile acids. 17 20 As expected Bhmt and Cth proteins were decreased by CA feeding but increased by Chol feeding (Fig. 2d). The effect of cholestyramine was more striking consistent with its efficacy to block BA reabsorption. In addition a high-fat diet feeding induced and expression (Fig. 2e) the latter was also observed by another group. 27 The induction could be a compensatory response to the excess fat weight in the liver as mice developed fatty liver. 3 We further examined the effects of fasting and refeeding but did not observe major changes in and expression under these conditions (Supplementary Fig. 3). Therefore it is postulated that this expression of and is primarily regulated by Shp rather than by the liver clock machinery. Their enhanced rhythmicity in and was controlled by SHP and FoxA1 crosstalk SHP is usually a unique member of the nuclear receptor superfamily in that it exerts its repressive function by suppressing the Nardosinone transactivation of other transcription factors (TFs).6 To elucidate the molecular basis by Nardosinone which SHP inhibits and expression we predicted TF response elements and identified conserved binding sites for FoxA1 in the mouse and promoters (Fig. 3a and Supplementary Fig. 4a). FoxA1 markedly induced Bhmt and Cth mRNA (Fig. 3b left) and Nardosinone protein (right) expression in mouse Hepa1-6 cells which was suppressed by Shp co-expression (right). Luciferase reporter assays exhibited that FoxA1 but not FoxA2 activated (Fig. 3c left) as well as (right) promoter and FoxA1 activation was completely blocked by Shp co-transfection. This is likely mediated by a physical conversation between SHP and FOXA1 proteins.28 In addition mutation of the binding site in promoter attenuated FoxA1 activity (Fig. 3d left) suggesting that this predicted site is at least in part responsible for FoxA1 activation of promoter (right) suggesting that this is a functional site for FoxA1. Importantly the recruitment of FoxA1 to the and promoters was rhythmic and overly augmented in and (Fig. 1a). FoxA1 was shown to.