Project description:N-acyl taurines (NAT) are endogenous, bioactive conjugates of fatty acids and taurine with roles in glucose and lipid metabolism. In the liver, NATs share the taurine conjugation enzyme, bile acid-CoA:amino acid N-acyltransferase (BAAT), with bile acids, suggesting the potential of an overlapping hepatic synthesis pathway. However, the remaining enzymes involved in NAT production in the liver remain unknown. This study aimed to investigate the overlap between hepatic NAT and bile acid synthesis to identify additional enzymes involved in NAT synthesis in the liver. Using transcriptomics of livers with altered NAT metabolism, we identified Slc27a5 which encodes fatty acid transport protein 5 (FATP5), as a potential node in the pathway. Knocking down the enzyme using siRNA in vivo confirmed that FATP5 is necessary for hepatic NAT synthesis and upstream of BAAT, likely through its acyl-CoA synthetase activity. The dual functions of this enzyme in activating both fatty acids and bile acids for conjugation implies functional overlap between the hepatic NAT and bile acid production pathway.
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:Data acquired for conjugated bile acids with amino acids analysis of human fecal samples by targeted LC-MS. These samples are a part of a study investigating a new BSH function as an amine N-acyl transferase that conjugates amines to form bacterial bile acid amidates (BBAAs).
Project description:Samples-WT Basal condition primary cortex cells; WT B27 Starved-Primary cortex cells starved overnight without B27 supplement media. WT AA Starved-Primary cortex cell starved without amino acid for 2 hours. WT AA Refed-Primary cortex cell refed for 1 hour after amino acid starvation. KO Basal-SLC38 Knockout Primary cortex cells starved overnight without B27 supplement media. KO B27 Starved-SLC38 Knockout Primary cortex cell starved without amino acid for 2 hours. KO AA starved-SLC38 Knockout Primary cortex cell refed for 1 hour after amino acid starvation. KO AA Refed-SLC38 Knockout Primary cortex cell refed for 1 hour after amino acid starvation.
Project description:full title: A mitochondrial long-chain fatty acid oxidation defect in a mouse model leads to dysregulation of plasma long-chain acylcarnitines, dysregulation of plasma amino acids, and an increased reliance on glucocorticoid signaling to maintain euglycemia during fasting. [liver] The liver is a major source of energy substrates during metabolic stress: fasting, prolonged exercise, febrile illness. Fasting-induced hypoglycemia is a characteristic feature of FAO disorders including very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). However, the pathophysiological mechanisms that underlie the diversity of clinical presentation of FAO dysfunction are not known. Here, we investigated the transcriptional response in liver tissue to the FAO defect in a model of VLCADD: the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse. We found that differentially expressed genes from the liver were associated with molecular networks annotated for fatty acid oxidation and cholesterol biosynthesis from population-based networks.
Project description:Nudix hydrolase 7 (NUDT7) is a peroxisomal (acyl-)CoA-degrading enzyme that is highly expressed in the liver. We previously showed that liver-specific NUDT7 overexpression affects peroxisomal lipid metabolism, but does not prevent the increase in total liver CoA levels that occurs with fasting. Herein, we show that deletion of Nudt7 alters the composition of the hepatic acyl-CoA pool in mice fed a low fat diet, but only in males fed a western diet does the lack of NUDT7 increase total liver CoA levels. This effect is driven by the accumulation of medium-chain dicarboxylic acyl-CoAs, which are products of the oxidation of dicarboxylic fatty acids in the peroxisomes. We also show that, under conditions of increased cholesterol intake and elevated bile acid synthesis, Nudt7 deletion increases the production of tauro-muricholic acids, decreasing the hydrophobicity index of the intestinal bile acid pool and increasing fecal cholesterol excretion. Collectively, our findings reveal a key role for NUDT7 in the regulation of the final products of bile acid synthesis and dicarboxylic fatty acid oxidation
Project description:A mitochondrial long-chain fatty acid oxidation defect leads to dysregulation of plasma long-chain acyl carnitines, dysregulation of plasma amino acids, and an increased reliance on glucocorticoid signaling to maintain euglycemia during fasting. [muscle] Skeletal muscle tissue relies on products of fatty acid oxidation (FAO) during conditions of metabolic stress: fasting, prolonged exercise, febrile illness. Fasting-induced hypoglycemia and rhabdomyolysis are characteristic features of FAO disorders including very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). However, the pathophysiological mechanisms that underlie the connection between FAO dysfunction and skeletal muscle dysfunction are not known. Here, we investigated the transcriptional response in skeletal muscle tissue (gastrocnemius) to the FAO defect in a model of VLCADD: the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse. We found that differentially expressed genes in the muscle were associated with molecular networks annotated for the cellular response to starvation from population-based models. To validate the association between the starvation response and FAO, we pharmacologically inhibited both glucocorticoid signaling and FAO in a model of fasting and observed that mice depleted in both pathways lost less weight during fasting and became hypoglycemic. These findings implicate glucocorticoid signaling as a candidate modifier of the cellular response to starvation in muscle tissue in the context of FAO disorders including VLCADD.
Project description:Background: Western diet (WD) fed Melanocortin 4 receptor-knockout (MC4R-KO) mice develop a phenotype resembling human metabolic dysfunction-associated steatohepatitis (MASH). Despite its clinical relevance, the role of the gut–liver axis in MASH pathogenesis remains unclear. This study investigated the gut-liver axis through microbiomic and metabolomic analyses of WD-fed MC4R-KO mice, and examined their association with MASH pathology. Methods: We performed an integrated microbiome and metabolome analysis of the liver, small intestinal contents, large intestinal contents, and plasma of wild-type (WT) and MC4R-KO mice fed either a normal diet or WD. Markers of hepatic inflammation, fibrosis, and steatosis measured in this study were used to assess MASH severity and to correlate microbiome and metabolite alterations. Results: WD-fed MC4R-KO mice exhibited significant hepatic steatosis, inflammation, and fibrosis. The abundance of certain microbiota, including Muribaculaceae and Allobaculum, negatively correlated with MASH severity, whereas increased levels of Desulfovibrionaceae and Bacteroides positively correlated with hepatic lipid accumulation, steatosis, and inflammation. Metabolomic profiling revealed increased triglyceride and diglyceride levels in the liver and a concomitant decrease in free fatty acids and monoglycerides in the intestines. Additionally, plasma taurine-conjugated bile acids were elevated in WD-fed MC4R-KO mice, which correlated with the reduced hepatic transport of bile salts from pathway enrichment analysis. These findings highlight substantial alterations in the gut microbiota and lipid and bile acid metabolism, indicating a mechanistic dysregulation of the gut–liver axis that may contribute to MASH progression. Conclusions: The observed gut microbial and metabolic alterations, particularly bile acid and lipid metabolism dysregulation, offer insights into potential therapeutic targets aimed at modulating the gut–liver axis to treat or prevent MASH.