Lactobacillus frumenti mediates energy production via fatty acid β-oxidation in the liver of early-weaned piglets

Background:Early-weaning of piglets is often accompanied by severe disorders,especially diarrhea.The gut microbiota and its metabolites play a critical role in the maintenance of the physiologic and metabolic homeostasis of the host.Our previous studies have demonstrated that oral administration of Lactobacillus frumenti improves epithelial barrier functions and confers diarrhea resistance in early-weaned piglets.However,the metabolic response to L.frumenti administration remains unclear.Then,we conducted simultaneous serum and hepatic metabolomic analyses in early-weaned piglets administered by L.frumenti or phosphatebuffered saline(PBS).Results:A total of 1006-day-old crossbred piglets(Landrace×Yorkshire)were randomly divided into two groups and piglets received PBS(sterile,2 m L)or L.frumenti(suspension in PBS,10~8 CFU/m L,2 m L)by oral administration once per day from 6 to 20 days of age.Piglets were weaned at 21 days of age.Serum and liver samples for metabolomic analyses were collected at 26 days of age.Principal components analysis(PCA)showed that L.frumenti altered metabolism in serum and liver.Numerous correlations(P<0.05)were identified among the serum and liver metabolites that were affected by L.frumenti.Concentrations of guanosine monophosphate(GMP),inosine monophosphate(IMP),and uric acid were higher in serum of L.frumenti administration piglets.Pathway analysis indicated that L.frumenti regulated fatty acid and amino acid metabolism in serum and liver.Concentrations of fatty acidβ-oxidation related metabolites in serum(such as3-hydroxybutyrylcarnitine,C4-OH)and liver(such as acetylcarnitine)were increased after L.frumenti administration.Conclusions:Our findings suggest that L.frumenti regulates lipid metabolism and amino acid metabolism in the liver of early-weaned piglets,where it promotes fatty acidβ-oxidation and energy production.High serum concentrations of nucleotide intermediates,which may be an alternative strategy to reduce the incidence of diarrhea in early-weaned piglets,were further detected.These findings broaden our understanding of the relationships between the gut microbiota and nutrient metabolism in the early-weaned piglets.

GhATL68b regulates cotton fiber cell development by ubiquitinating the enzyme required forβ-oxidation of polyunsaturated fatty acids

E3 ligases are key enzymes required for protein degradation.Here,we identified a C3H2C3 RING domaincontaining E3 ubiquitin ligase gene named GhATL68b.It is preferentially and highly expressed in developing cotton fiber cells and shows greater conservation in plants than in animals or archaea.The four orthologous copies of this gene in various diploid cottons and eight in the allotetraploid G.hirsutum were found to have originated from a single common ancestor that can be traced back to Chlamydomonas reinhardtii at about 992 million years ago.Structural variations in the GhATL68b promoter regions of G.hirsutum,G.herbaceum,G.arboreum,and G.raimondii are correlated with significantly different methylation patterns.Homozygous CRISPR-Cas9 knockout cotton lines exhibit significant reductions in fiber quality traits,including upper-half mean length,elongation at break,uniformity,and mature fiber weight.In vitro ubiquitination and cell-free protein degradation assays revealed that GhATL68b modulates the homeostasis of 2,4-dienoyl-CoA reductase,a rate-limiting enzyme for theβ-oxidation of polyunsaturated fatty acids(PUFAs),via the ubiquitin proteasome pathway.Fiber cells harvested from these knockout mutants contain significantly lower levels of PUFAs important for production of glycerophospholipids and regulation of plasma membrane fluidity.The fiber growth defects of the mutant can be fully rescued by the addition of linolenic acid(C18:3),the most abundant type of PUFA,to the ovule culture medium.This experimentally characterized C3H2C3 type E3 ubiquitin ligase involved in regulating fiber cell elongation may provide us with a new genetic target for improved cotton lint production.

Mitochondrial carnitine palmitoyltransferase-Ⅱ dysfunction: A possible novel mechanism for nonalcoholic fatty liver disease in hepatocarcinogenesis

Nonalcoholic fatty liver disease(NAFLD)or metabolic-associated fatty liver disease has been characterized by the lipid accumulation with injury of hepatocytes and has become one of the most common chronic liver diseases in the world.The complex mechanisms of NAFLD formation are still under identification.Carnitine palmitoyltransferase-Ⅱ(CPT-Ⅱ)on inner mitochondrial membrane(IMM)regulates long chain fatty acidβ-oxidation,and its abnormality has had more and more attention paid to it by basic and clinical research in NAFLD.The sequences of its peptide chain and DNA nucleotides have been identified,and the catalytic activity of CPT-Ⅱ is affected on its gene mutations,deficiency,enzymatic thermal instability,circulating carnitine level and so on.Recently,the CPT-Ⅱ dysfunction has been discovered in models of liver lipid accumulation.Meanwhile,the malignant transformation of hepatocyte-related CD44^(+) stem T cell activation,high levels of tumor-related biomarkers(AFP,GPC3)and abnormal activation of Wnt3a expression as a key signal molecule of the Wnt/β-catenin pathway run parallel to the alterations of hepatocyte pathology.This review focuses on some of the progress of CPT-Ⅱ inactivity on IMM with liver fatty accumulation as a possible novel pathogenesis for NAFLD in hepatocarcinogenesis.

血清肠脂肪酸结合蛋白联合多层螺旋CTA诊断急性缺血性肠病价值的研究

目的通过比较急性缺血性肠病与非急性缺血性肠病患者血清肠脂肪酸结合蛋白(I-FABP)及多层螺旋CT血管造影(MSCTA)的影像特征,分析两者之间的相关性、比较两者对急性缺血性肠病的诊断效能。方法选取南宁市第一人民医院2015年3月至2020年12月的急性腹痛患者65例,其中30例急性缺血性肠病的患者为观察组,另外35例非急性缺血性肠病患者为对照组,比较血清I-FABP与MSCTA评分对急性缺血性肠病诊断效能的高低并探究两者联合的诊断效能。结果观察组血清I-FABP水平及MSCTA评分均高于对照组,差异有统计学意义(P<0.05);血清I-FABP水平及MSCTA评分均对急性缺血性肠病诊断有影响(P<0.05);血清I-FABP水平诊断急性缺血性肠病的截断值为125.65 g/L,MSCTA评分诊断急性缺血性肠病的截断值为2.5分,血清I-FABP水平、MSCTA评分、联合检测诊断急性缺血性肠病的ROC曲线下面积分别为0.880、0.761、0.885;联合检测较MSCTA评分诊断效能高(P<0.05)。结论血清I-FABP检测联合MSCTA有助于提高急性缺血性肠病的诊断效能。

A robust,integrated platform for comprehensive analyses of acylcoenzyme As and acyl-carnitines revealed chain length-dependent disparity in fatty acyl metabolic fates across Drosophila development

Acyl-coenzyme A thioesters(acyl-CoAs)denote a key class of intermediary metabolites that lies at the hub of major metabolic pathways.The great diversity in polarity between short-and long-chain acylCoAs makes it technically challenging to cover an inclusive range of acyl-CoAs within a single method.Levels of acyl-carnitines,which function to convey fatty acyls into mitochondria matrix forβ-oxidation,indicate the efficiency of mitochondrial import and utilization of corresponding acyl-CoAs.Herein,we report a robust,integrated platform to allow simultaneous quantitation of endogenous acyl-CoAs and acyl-carnitines.Using this method,we monitored changes in intermediary lipid profiles across Drosophila development under control(ND)and high-fat diet(HFD).We observed specific accumulations of medium-chain(C8-C12)and long-chain(≥C16)acyl-carnitines distinct to L3 larval and pupal stages,respectively.These observations suggested development-specific,chain length-dependent disparity in metabolic fates of acyl-CoAs across Drosophila development,which was validated by deploying the same platform to monitor isotope incorporation introduced from labelled 12:0 and 16:0 fatty acids into extra-and intra-mitochondrial acyl-CoA pools.We found that pupal mitochondria preferentially import and oxidise C12:0-CoAs(accumulated as C12:0-carnitines in L3 stage)over C16:0-CoAs.Preferential oxidation of medium-chain acyl-CoAs limits mitochondrial utilization of long-chain acyl-CoAs(C16-C18),leading to pupal-specific accumulation of long-chain acyl-carnitines mediated by enhanced CPT1-6 A activity.HFD skewed C16:0-CoAs towards catabolism over anabolism in pupa,thereby adversely affecting overall development.Our developed platform emphasizes the importance of integrating biological knowledge in the design of pathway-oriented platforms to derive maximal physiological insights from analysis of complex biological systems.

线虫烯脂酰CoA水合酶的克隆、表达、纯化及初步晶体学分析

生物体β-氧化循环是脂肪酸氧化分解的主要途径,许多代谢疾病都与其密切相关。线虫β-氧化循环与人类相似,但与其相关的研究报道却很少。线虫基因C32E8.9编码的蛋白被WormBase命名为烯脂酰CoA水合酶(WormBase ID:CE29693),被推测具有催化β-氧化循环第二步反应的功能。作者将C32E8.9基因克隆到原核表达载体上,在大肠杆菌中获得高效表达,并分别纯化了母体蛋白以及硒代蛋白衍生物。多角度静态光散射实验表明该蛋白的聚合状态为三聚体。该蛋白在沉淀剂2-甲基-2,4-戊二醇的作用下形成可供衍射分析的六棱柱形状晶体,空间群为P21,晶胞参数为a=79.0,b=82.4,c=79.2,α=γ=90.0°,β=120°,数据分析表明该晶体非单晶,是一种罕见的蛋白质"三晶"——包含三套晶格。

Metabolic dysregulation and emerging therapeutical targets for hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is an aggressive human cancer with increasing incidence worldwide.Multiple efforts have been made to explore pharmaceutical therapies to treat HCC,such as targeted tyrosine kinase inhibitors,immune based therapies and combination of chemotherapy.However,limitations exist in current strategies including chemoresistance for instance.Tumor initiation and progression is driven by reprogramming of metabolism,in particular during HCC development.Recently,metabolic associated fatty liver disease(MAFLD),a reappraisal of new nomenclature for nonalcoholic fatty liver disease(NAFLD),indicates growing appreciation of metabolism in the pathogenesis of liver disease,including HCC,thereby suggesting new strategies by targeting abnormal metabolism for HCC treatment.In this review,we introduce directions by highlighting the metabolic targets in glucose,fatty acid,amino acid and glutamine metabolism,which are suitable for HCC pharmaceutical intervention.We also summarize and discuss current pharmaceutical agents and studies targeting deregulated metabolism during HCC treatment.Furthermore,opportunities and challenges in the discovery and development of HCC therapy targeting metabolism are discussed.

PSA controls hepatic lipid metabolism by regulating the NRF2 signaling pathway

The activity of proteinase is reported to correlate with the development and progression of nonalcoholic fatty liver disease(NAFLD).Puromycin-sensitive aminopeptidase(PSA/NPEPPS)is an integral nontransmembrane enzyme that functions to catalyze the cleavage of amino acids near the N-terminus of polypeptides.A previous study suggested that this enzyme acts as a regulator of neuropeptide activity;however,the metabolic function of this enzyme in the liver has not been explored.Here,we identified the novel role of PSA in hepatic lipid metabolism.Specifically,PSA expression was lower in fatty livers from NAFLD patients and mice(HFD,ob/ob,and db/db).PSA knockdown in cultured hepatocytes exacerbated diet-induced triglyceride accumulation through enhanced lipogenesis and attenuated fatty acid β-oxidation.Moreover,PSA mediated activation of the master regulator of antioxidant response,nuclear factor erythroid 2-related factor 2(NRF2),by stabilizing NRF2 protein expression,which further induced downstream antioxidant enzymes to protect the liver from oxidative stress and lipid overload.Accordingly,liver-specific PSA overexpression attenuated hepatic lipid accumulation and steatosis in ob/ob mice.Furthermore,in human liver tissue samples,decreased PSA expression correlated with the progression of NAFLD.Overall,our findings suggest that PSA is a pivotal regulator of hepatic lipid metabolism and its antioxidant function occurs by suppressing NRF2 ubiquitination.Moreover,PSA may be a potential biomarker and therapeutic target for treating NAFLD.

Endocrine pheromones couple fat rationing to dauer diapause through HNF4αnuclear receptors

Developmental diapause is a widespread strategy for animals to survive seasonal starvation and environmental harshness.Diapaused animals often ration body fat to generate a basal level of energy for enduring survival.How diapause and fat rationing are coupled,however,is poorly understood.The nematode Caenorhabditis elegans excretes pheromones to the environment to induce a diapause form called dauer larva.Through saturated forward genetic screens and CRISPR knockout,we found that dauer pheromones feed back to repress the transcription of ACOX-3,MAOC-1,DHS-28,DAF-22(peroxisomalβ-oxidation enzymes dually involved in pheromone synthesis and fat burning),ALH-4(aldehyde dehydrogenase for pheromone synthesis),PRX-10 and PRX-11(peroxisome assembly and proliferation factors).Dysfunction of these pheromone enzymes and factors relieves the repression.Surprisingly,transcription is repressed not by pheromones excreted but by pheromones endogenous to each animal.The endogenous pheromones regulate the nuclear translocation of HNF4αfamily nuclear receptor NHR-79 and its co-receptor NHR-49,and,repress transcription through the two receptors.The feedback repression maintains pheromone homeostasis,increases fat storage,decreases fat burning,and prolongs dauer lifespan.Thus,the exocrine dauer pheromones possess an unexpected endocrine function to mediate a peroxisome-nucleus crosstalk,coupling dauer diapause to fat rationing.