Project description:The molecular mechanisms by which dietary fruits and vegetables confer cardiometabolic benefits remain poorly understood. Historically, these beneficial properties have been attributed to the antioxidant activity of flavonoids. Here, we reveal that the host metabolic benefits associated with flavonoid consumption actually hinge on gut microbial metabolism. However, flavonoids are consumed in a largely glycosylated form, rendering them poorly available for small intestinal absorption and subjecting them to microbial metabolism in the colon. We show that a single gut microbial flavonoid catabolite is sufficient to reduce diet-induced cardiometabolic disease burden in mice. Dietary supplementation with elderberry extract attenuated obesity and continuous delivery of the catabolite 4-hydroxphenylacetic acid was sufficient to reverse hepatic steatosis. Analysis of human gut metagenomes revealed that under one percent contains a flavonol catabolic pathway, underscoring the rarity of this process. Our study will impact the design of dietary and probiotic interventions to complement traditional cardiometabolic treatment strategies.
Project description:Reprogramming in vivo using OCT4, SOX2, KLF4 and MYC (OSKM) triggers cell dedifferentiation, which is considered of relevance for tissue repair and regeneration. However, little is known about the metabolic requirements of this process. We found that antibiotic depletion of the gut microbiota abolished in vivo reprogramming. Analysis of bacterial metagenomes from stool samples of wild type (WT) and OSKM mice treated with doxycycline led us to identify vitamin B12 as a key factor for in vivo reprogramming, which is partly supplied by the microbiome. We report that B12 demand increases during reprogramming due to enhanced expression of enzymes in the methionine cycle, and supplementing B12 levels both in vitro and in vivo enhances the efficiency of OSKM reprogramming.
Project description:Urolithin A is a polyphenol derived from the multi-step metabolism of dietary ellagitannins by the human gut microbiota which can affect host health. Most, but not all, individuals harbor a microbiota capable of urolithin A production; however, the enzymes that dehydroxylate its dietary precursor, urolithin C, are unknown. Here, we used a combination of transcriptomics and proteomics to reveal a urolithin C dehydroxylase (ucd) operon that dehydroxylates 9-hydroxy urolithin compounds in Enterocloster spp. Using comparative genomics, we identified Lachnoclostridium pacaense as a novel urolithin C metabolizer. Biochemical characterization and structure predictions of proteins in the Ucd complex demonstrated that dehydroxylation was both NADH- and molybdopterin-dependent and used urolithin C as a terminal electron acceptor. A meta-analysis publicly available metagenomic data revealed that both bacteria and ucd operon genes are widely distributed in gut metagenomes and likely comprise keystone species in the metabolism of urolithins by the human gut microbiota.
Project description:Casein is a common source of dietary protein in defined diets used to investigate the effect of diet on the gut microbiota. Previously it has been shown that the metagenomes of mice fed with a diet containing casein were contaminated with DNA from the bacterium Lactococcus lactis and that washing the casein with ethanol removed this contamination (https://doi.org/10.1016/j.chom.2019.06.013). We have identified the same phenomenon when identifying proteins from mouse diets with casein However, in contrast to DNA sequencing we did not see a reduction in L. lactis contamination in proteomes. Two lots each of standard casein and ethanol-washed casein were analyzed using proteomics.