Background:Most duck eggs possess a fishy odor,indicating that ducks generally exhibit impaired trimethylamine(TMA)metabolism.TMA accumulation is responsible for this unpleasant odor,and TMA metabolism plays an essen-...Background:Most duck eggs possess a fishy odor,indicating that ducks generally exhibit impaired trimethylamine(TMA)metabolism.TMA accumulation is responsible for this unpleasant odor,and TMA metabolism plays an essen-tial role in trimethylaminuria(TMAU),also known as fish odor syndrome.In this study,we focused on the unusual TMA metabolism mechanism in ducks,and further explored the unclear reasons leading to the debilitating TMA metabolism.Methods:To achieve this,transcriptome,proteome,and metagenome analyses were first integrated based on the constructed duck populations with high and low TMA metabolism abilities.Additionally,further experiments were conducted to validate the hypothesis regarding the limited flavin-containing monooxygenase 3(FMO3)metabolism ability of ducks.Results:The study demonstrated that liver FMO3 and cecal microbes,including Akkermansia and Mucispirillum,par-ticipated in TMA metabolism in ducks.The limited oxidation ability of FMO3 explains the weakening of TMA metabo-lism in ducks.Nevertheless,it decreases lipid deposition and increases antibacterial activity,contributing to its survival and reproduction during the evolutionary adaptation process.Conclusions:This study demonstrated the function of FMO3 and intestinal microbes in regulating TMA metabolism and illustrated the biological significance of FMO3 impairment in ducks.展开更多
The association among plasma trimethylamine-N-oxide(TMAO),FMO3 polymorphisms,and chronic heart failure(CHF)remains to be elucidated.TMAO is a microbiota-dependent metabolite from dietary choline and carnitine.A prospe...The association among plasma trimethylamine-N-oxide(TMAO),FMO3 polymorphisms,and chronic heart failure(CHF)remains to be elucidated.TMAO is a microbiota-dependent metabolite from dietary choline and carnitine.A prospective study was performed including 955 consecutively diagnosed CHF patients with reduced ejection fraction,with the longest follow-up of 7 years.The concentrations of plasma TMAO and its precursors,namely,choline and carnitine,were determined by liquid chromatography-mass spectrometry,and the FMO3 E158K polymorphisms(rs2266782)were genotyped.The top tertile of plasma TMAO was associated with a significant increment in hazard ratio(HR)for the composite outcome of cardiovascular death or heart transplantation(HR=1.47,95%CI=1.13-1.91,P=0.004)compared with the lowest tertile.After adjustments of the potential confounders,higher TMAO could still be used to predict the risk of the primary endpoint(adjusted HR=1.33,95%CI=1.01-1.74,P=0.039).This result was also obtained after further adjustment for carnitine(adjusted HR=1.33,95%CI=1.01-1.74,P=0.039).The FM03 rs2266782 polymorphism was associated with the plasma TMAO concentrations in our cohort,and lower TMAO levels were found in the AA-genotype.Thus,higher plasma TMAO levels indicated increased risk of the composite outcome of cardiovascular death or heart transplantation independent of potential confounders,and the FMO3 AA-genotype in rs2266782 was related to lower plasma TMAO levels.展开更多
The aim of this study was to examine whether flavin-containing monooxygenase (FMO) protein was expressed in cultured rat brain microvascular endothelial cells (BMECs), which constitute the blood-brain barrier (BBB), a...The aim of this study was to examine whether flavin-containing monooxygenase (FMO) protein was expressed in cultured rat brain microvascular endothelial cells (BMECs), which constitute the blood-brain barrier (BBB), and whether N-oxide from the tertiary amine, d-chlorpheniramine, was formed by FMO in rat BMECs. BMECs were isolated and cultured from the brains of three-week-old male Wistar rats. The expression of FMO1, FMO2 and FMO5 proteins was confirmed in rat BMECs by western blotting analysis using polyclonal anti-FMO antibodies, but FMO3 and FMO4 proteins were not found in the rat BBB. Moreover, N-oxide of d-chlorpheniramine was formed in rat BMECs. The intrinsic clearance value for N-oxidation at pH 8.4 was higher than that at pH 7.4. Inhibition of N-oxide formation by methimazole was found to be the best model of competitive inhibition yielding an apparent Ki value of 0.53 μmol/L, suggesting that N-oxidation was catalyzed by FMOs in rat BMECs. Although FMO activity in rat BMECs was lower than that in SD rat normal hepatocytes (rtNHeps), we suggest that rat BMECs enzymes can convert substrates of exogenous origin for detoxification, indicating that BMECs are an important barrier for metabolic products besides hepatic cells.展开更多
Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidiz...Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food.展开更多
基金supported by the National Natural Science Foundation of China(31672408)the China Agriculture Research Systems(CARS-40)+1 种基金the National Key Research and Development Program of China(2021YFD1200803)the Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R62).
文摘Background:Most duck eggs possess a fishy odor,indicating that ducks generally exhibit impaired trimethylamine(TMA)metabolism.TMA accumulation is responsible for this unpleasant odor,and TMA metabolism plays an essen-tial role in trimethylaminuria(TMAU),also known as fish odor syndrome.In this study,we focused on the unusual TMA metabolism mechanism in ducks,and further explored the unclear reasons leading to the debilitating TMA metabolism.Methods:To achieve this,transcriptome,proteome,and metagenome analyses were first integrated based on the constructed duck populations with high and low TMA metabolism abilities.Additionally,further experiments were conducted to validate the hypothesis regarding the limited flavin-containing monooxygenase 3(FMO3)metabolism ability of ducks.Results:The study demonstrated that liver FMO3 and cecal microbes,including Akkermansia and Mucispirillum,par-ticipated in TMA metabolism in ducks.The limited oxidation ability of FMO3 explains the weakening of TMA metabo-lism in ducks.Nevertheless,it decreases lipid deposition and increases antibacterial activity,contributing to its survival and reproduction during the evolutionary adaptation process.Conclusions:This study demonstrated the function of FMO3 and intestinal microbes in regulating TMA metabolism and illustrated the biological significance of FMO3 impairment in ducks.
基金This work was supported by National Key R&D Program of China(Nos.2017YFC0909400 and 2017YFC1307700)Projects from National Natural Science Foundation of China(Nos.81630010,91639108,81770272,81873506,82070235,and 81790624)+3 种基金the Beijing Municipal Natural Science Foundation(No.7191013)China Postdoctoral Science Foundation(No.2020M680261)National Postdoctoral Program for Innovative Talents(No.BX20200022)Integrated Innovative Team for Human Disease Program of Tongji Medical College,HUST(No.2015ZDTD044).
文摘The association among plasma trimethylamine-N-oxide(TMAO),FMO3 polymorphisms,and chronic heart failure(CHF)remains to be elucidated.TMAO is a microbiota-dependent metabolite from dietary choline and carnitine.A prospective study was performed including 955 consecutively diagnosed CHF patients with reduced ejection fraction,with the longest follow-up of 7 years.The concentrations of plasma TMAO and its precursors,namely,choline and carnitine,were determined by liquid chromatography-mass spectrometry,and the FMO3 E158K polymorphisms(rs2266782)were genotyped.The top tertile of plasma TMAO was associated with a significant increment in hazard ratio(HR)for the composite outcome of cardiovascular death or heart transplantation(HR=1.47,95%CI=1.13-1.91,P=0.004)compared with the lowest tertile.After adjustments of the potential confounders,higher TMAO could still be used to predict the risk of the primary endpoint(adjusted HR=1.33,95%CI=1.01-1.74,P=0.039).This result was also obtained after further adjustment for carnitine(adjusted HR=1.33,95%CI=1.01-1.74,P=0.039).The FM03 rs2266782 polymorphism was associated with the plasma TMAO concentrations in our cohort,and lower TMAO levels were found in the AA-genotype.Thus,higher plasma TMAO levels indicated increased risk of the composite outcome of cardiovascular death or heart transplantation independent of potential confounders,and the FMO3 AA-genotype in rs2266782 was related to lower plasma TMAO levels.
文摘The aim of this study was to examine whether flavin-containing monooxygenase (FMO) protein was expressed in cultured rat brain microvascular endothelial cells (BMECs), which constitute the blood-brain barrier (BBB), and whether N-oxide from the tertiary amine, d-chlorpheniramine, was formed by FMO in rat BMECs. BMECs were isolated and cultured from the brains of three-week-old male Wistar rats. The expression of FMO1, FMO2 and FMO5 proteins was confirmed in rat BMECs by western blotting analysis using polyclonal anti-FMO antibodies, but FMO3 and FMO4 proteins were not found in the rat BBB. Moreover, N-oxide of d-chlorpheniramine was formed in rat BMECs. The intrinsic clearance value for N-oxidation at pH 8.4 was higher than that at pH 7.4. Inhibition of N-oxide formation by methimazole was found to be the best model of competitive inhibition yielding an apparent Ki value of 0.53 μmol/L, suggesting that N-oxidation was catalyzed by FMOs in rat BMECs. Although FMO activity in rat BMECs was lower than that in SD rat normal hepatocytes (rtNHeps), we suggest that rat BMECs enzymes can convert substrates of exogenous origin for detoxification, indicating that BMECs are an important barrier for metabolic products besides hepatic cells.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China (2008ZX10005-004)Educational Commission of Liaoning Province of China (2009A120)China Postdoctoral Science Foundation (20080440019 and 200902069)
文摘Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food.
