. measured for 8 days. The feces were collected every 2 days for 8 days. Ileal and fecal lipids were extracted as described in the Supplemental Methods. Triglycerides were measured with a triglyceride colorimetric assay kit (Bioassay Systems). Free fatty acids (FFAs) were measured using reagents from Wako.Statistics. Experimental values are presented as the mean ± SD. Statistical analyses were performed using the 2-tailed Student's t test and 1-way ANOVA with Tukey's confirmation. Weighted UniFrac analysis to assess changes in bacterial abundance was performed on the Galaxy web-based platform. Statistical models including PCA, PLS-DA, and OPLS-DA were established to represent the major latent variables in the data matrix. P values of less than 0.05 were considered significant. Study approval. All animal studies were performed in accordance with the Institute of Laboratory Animal Resources guidelines and approved by the IACUC of the NCI.

No abstract

The farnesoid X receptor (FXR) regulates bile acid, lipid and glucose metabolism. Here we show that treatment of mice with glycine-β-muricholic acid (Gly-MCA) inhibits FXR signalling exclusively in intestine, and improves metabolic parameters in mouse models of obesity. Gly-MCA is a selective high-affinity FXR inhibitor that can be administered orally and prevents, or reverses, high-fat diet-induced and genetic obesity, insulin resistance and hepatic steatosis in mice. The high-affinity FXR agonist GW4064 blocks Gly-MCA action in the gut, and intestine-specific Fxr-null mice are unresponsive to the beneficial effects of Gly-MCA. Mechanistically, the metabolic improvements with Gly-MCA depend on reduced biosynthesis of intestinal-derived ceramides, which directly compromise beige fat thermogenic function. Consequently, ceramide treatment reverses the action of Gly-MCA in high-fat diet-induced obese mice. We further show that FXR signalling in ileum biopsies of humans positively correlates with body mass index. These data suggest that Gly-MCA may be a candidate for the treatment of metabolic disorders.

Background: It remains a matter of debate whether autophagy contributes to apoptosis. Results: Atg5 and p62 are required for an intracellular death-inducing signaling complex (iDISC) formation on autophagosomal membranes for caspase-8 self-processing. Conclusion: Autophagosome serves as a platform for the intracellular activation of caspase-8. Significance: Induction of iDISC formation may shift cytoprotective autophagy to apoptosis for more effective cancer therapies.

Ligand activation of the aryl hydrocarbon (AHR) has profound effects upon the immunological status of the gastrointestinal tract, establishing and maintaining signaling networks, which facilitate host-microbe homeostasis at the mucosal interface. However, the identity of the ligand(s) responsible for such AHR-mediated activation within the gut remains to be firmly established. Here, we combine in vitro ligand binding, quantitative gene expression, protein-DNA interaction and ligand structure activity analyses together with in silico modeling of the AHR ligand binding domain to identify indole, a microbial tryptophan metabolite, as a human-AHR selective agonist. Human AHR, acting as a host indole receptor may exhibit a unique bimolecular (2:1) binding stoichiometry not observed with typical AHR ligands. Such bimolecular indole-mediated activation of the human AHR within the gastrointestinal tract may provide a foundation for inter-kingdom signaling between the enteric microflora and the immune system to promote commensalism within the gut.

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor involved in the regulation of multiple cellular pathways, such as xenobiotic metabolism and Th17 cell differentiation. Identification of key physiologically relevant ligand(s) that regulate AHR function remains to be accomplished. Screening of indole metabolites has identified indoxyl-3-sulfate (I3S) as a potent endogenous ligand that selectively activates the human AHR at nanomolar concentrations in primary human hepatocytes, regulating transcription of multiple genes, including: CYP1A1, CYP1A2, CYP1B1, UGT1A1, UGT1A6, IL6, and SAA1. Furthermore, I3S exhibits an ~ 500-fold greater potency in terms of transcriptional activation of the human AHR relative to the mouse AHR in cell lines. Structure-function studies reveal that the sulfate group is important determinant for efficient AHR activation. This is the first phase II enzymatic product identified that can significantly activate the AHR and ligand competition binding assays indicate that I3S is a direct AHR ligand. I3S failed to activate either CAR or PXR. The physiological importance of I3S lies in the fact that it is a key uremic toxin that accumulates to high micromolar concentrations in kidney dialysis patients, but its mechanism of action is unknown. I3S represents the first identified relatively high potency endogenous AHR ligand that plays a key role in human disease progression. These studies provide evidence that the production of I3S can lead to AHR activation and altered drug metabolism. Our results also suggest that prolonged activation of the AHR by I3S may contribute to toxicity observed in kidney dialysis patients and thus represent a possible therapeutic target.The aryl hydrocarbon receptor (AHR) 1 is a ligand-activated transcription factor that belongs to the basic helix-loop-helix/Per-Arnt-Sim (bHLH/PAS) family of transcription factors, a class of proteins that are considered environmental sensors. Prior to activation, the AHR is located in the cytoplasm of the cell, complexed with two heat-shock protein 90 molecules, X-associated

No abstract

The present study shows that oral gavage of 6 Mmol D,Lsulforaphane (SFN), a synthetic analogue of cruciferous vegetable-derived L isomer, thrice per week beginning at 6 weeks of age, significantly inhibits prostate carcinogenesis and pulmonary metastasis in TRAMP mice without causing any side effects. The incidence of the prostatic intraepithelial neoplasia and well-differentiated (WD) carcinoma were f23% to 28% lower (P < 0.05 compared with control by MannWhitney test) in the dorsolateral prostate (DLP) of SFNtreated mice compared with controls, which was not due to the suppression of T-antigen expression. The area occupied by the WD carcinoma was also f44% lower in the DLP of SFNtreated mice relative to that of control mice (P = 0.0011 by Mann Whitney test). Strikingly, the SFN-treated mice exhibited f50% and 63% decrease, respectively, in pulmonary metastasis incidence and multiplicity compared with control mice (P < 0.05 by t test). The DLP from SFN-treated mice showed decreased cellular proliferation and increased apoptosis when compared with that from control mice. Additionally, SFN administration enhanced cytotoxicity of cocultures of natural killer (NK) cells and dendritic cells (DC) against TRAMP-C1 target cells, which correlated with infiltration of T cells in the neoplastic lesions and increased levels of interleukin-12 production by the DC. In conclusion, the results of the present study indicate that SFN administration inhibits prostate cancer progression and pulmonary metastasis in TRAMP mice by reducing cell proliferation and augmenting NK cell lytic activity.