Project description:Bile acids are multifunctional signaling molecules that play significant roles in maintaining microbial homeostasis. N6-methyladenine (m6A), the most abundant epitranscriptomic modification, mediates various biological processes by modulating RNA metabolism. However, the precise regulatory mechanisms of m6A methylation in bile acid metabolism, and its downstream effects on microbiota remain unclear. In this study, liver-specific Mettl14 knockout (Mettl14-LKO) reshaped bile acid profile and expression levels of protein related to bile acid metabolism, namely CYP7A1, FXR, and BSEP. M6A-seq data revealed m6A methylated peaks on CYP7A1. Mettl14-LKO significantly elevated expression of m6A “reader” IGF2BP3. Knockdown of IGF2BP3 inhibited CYP7A1 expression by decreasing mRNA stability. Mechanistically, Mettl14-LKO promoted bile acid synthesis by upregulating CYP7A1 expression in an m6A-IGF2BP3-dependent manner. Interestingly, Mettl14-LKO reduced bile acid content in ileum due to decreased BSEP level in liver. Noteworthy, we discovered for the first time that Mettl14 knockout in the liver altered fecal microbiota composition. Specifically, it changed the abundance of Cyanobacteria and Patescibacteria at phylum level, and Lachnochostridium, Candidatus-Saccharimonas, and Roseburia at genera level. Remarkably, Roseburia was negatively correlated with the bile acid levels and CYP7A1 expression. Our findings provide new insights into the role of METTL14 in regulating bile acid homeostasis and its impact on fecal microbiota. Roseburia emerges as a potential target for addressing metabolic diseases linked to disrupted METTL14 signaling.
Project description:Targeted metabolomics performed by GC-MS (for SCFAs by PFBBr derivatization) and LC-MS (for bile acids) on fecal samples from liver transplant patients.
Project description:Objective Crohn’s Disease (CD) and Ulcerative Colitis (UC) are chronic inflammatory diseases of the gastrointestinal tract. Reliable diagnosis of these diseases requires a comprehensive examination of the patient, which include invasive endoscopy. This study assesses whether non-invasive LC-MS/MS based analysis of microbial and human proteins from feces may support the diagnosis of the diseases. Design In order to mimic a representative clinical background for this study, we investigated 17 healthy controls, 11 CD patients, 14 UC patients, also 13 Irritable Bowel Disease (IBS) patients, 8 Colon Adenoma (CA) patients, and 8 Gastric Carcinoma (GCA) patients. The proteins were extracted from the fecal samples with liquid phenol in a ball mill. Subsequently, the proteins were digested tryptically to peptides and analyzed by liquid chromatography coupled to an Orbitrap MS/MS. For protein identification and interpretation of taxonomic and functional results, the MetaProteomeAnalyzer software and the UniProtKB/SwissProt database and several metagenomes from human fecal samples were used. Results Cluster analysis and ANOSIM show a separation of healthy controls from patients with CD and UC as well as from patients with GCA. Among others, UC and CD correlated with an increase of neutrophil extracellular traps and immunoglobulins G (IgG) as well as a decrease of IgA. A specific marker metaprotein for CD was an increase of the human enzyme sucrose-isomaltase. IBS and CA patient’s fecal metaproteome showed only minor alterations. Conclusion Metaproteome analysis distinguished between patients with UC, CD and healthy controls and is therefore useful as a non-invasive tool for routine diagnostics in hospitals.
Project description:Fecal samples from centenarians (>100 yo), elderly (85-89 yo) and young (21-55) subjects were analysed using LC-MS/MS. 48 bile acids were measured by targeted metabolomics.