Carbohydrate-specific signaling through the DC-SIGN

分解代谢英语Catabolism, a fundamental biological process, refers tothe set of metabolic pathways that break down molecules into smaller units. This process is crucial for providing the energy and basic components necessary for the proper functioning of living organisms. In this article, we willdelve into the intricacies of catabolism, exploring itsvarious types, the role of enzymes, and the significance ofthis process in cellular metabolism.Types of Catabolism1. Lipolysis: This is the breakdown of fats into glycerol and fatty acids, which can then be used for energy production.2. Proteolysis: Proteins are broken down into amino acids through this process, which can be further utilized invarious metabolic pathways.3. Carbohydrate Metabolism: The digestion and breakdownof carbohydrates, such as starch and glycogen, into glucose, which serves as a primary energy source for cells.Enzymatic Action in CatabolismEnzymes play a pivotal role in catabolism by catalyzingthe reactions that break down complex molecules. These biological catalysts speed up the rate at which catabolismoccurs without being consumed in the process. Some key enzymes involved in catabolism include:- Lipases: Facilitate the breakdown of lipids into fatty acids and glycerol.- Proteases: Aid in the hydrolysis of peptide bonds, resulting in the formation of amino acids.- Amylases: Break down complex carbohydrates into simpler sugars.Significance in Cellular MetabolismCatabolism is essential for several reasons:1. Energy Production: The breakdown of molecules releases energy that can be harnessed by cells to perform work.2. Molecule Recycling: Catabolism allows for therecycling of molecules, which is particularly important in maintaining a balance of nutrients within the body.3. Regulation of Metabolic Pathways: The products of catabolism can act as signaling molecules, regulating other metabolic processes.ConclusionCatabolism is a vital process that underpins the energy economy of cells. It involves the breakdown of macromoleculesinto simpler forms, which can then be used for energy or as building blocks for the synthesis of new cellular components. Understanding the mechanisms and significance of catabolism is key to comprehending the broader scope of cellular metabolism and the interplay between anabolic and catabolic processes.This article provides a concise overview of catabolism, avoiding unnecessary repetition and maintaining a clear, informative structure. The language is formal and appropriate for an educational context, and the content is presented in a logical sequence for easy comprehension.。

Biosynthesis and Biosynthetic PathwaysBiosynthesis is the process by which living organisms, both plants and animals, produce complex and essential organic molecules from simpler ones. These organic molecules include amino acids, nucleotides, carbohydrates, lipids, and many other compounds required for the growth, development, and functioning of cells and tissues. Biosynthesis occurs through a series of chemical reactions, which are catalyzed by specific enzymes. These enzymatic reactions are organized into biosynthetic pathways, which are highly regulated and controlled by various mechanisms to ensure a proper balance of substrate utilization, product formation, and energy conservation.Amino Acid BiosynthesisAmino acids are the building blocks of proteins, which are essential macromolecules that perform a wide range of biological functions. There are 20 amino acids that are commonly found in proteins, and each of them can be synthesized de novo by living organisms, starting from simpler precur sors such as glucose, pyruvate, or α-ketoglutarate. The biosynthetic pathways for amino acids are diverse and complex, involving multiple steps and intermediates, as well as various cofactors and regulatory molecules. For example, the biosynthesis of alanine, a non-essential amino acid, involves the conversion of pyruvate to alanine via transamination and reductive amination reactions, which are catalyzed by the enzymes alanine transaminase and alanine dehydrogenase, respectively. Other amino acids, such as lysine and tryptophan, require complex pathways involving multiple enzymes and feedback inhibition mechanisms.Nucleotide BiosynthesisNucleotides are the basic units of DNA and RNA, which are the genetic materials that encode and transmit the genetic information of living organisms. Nucleotides also serve as energy carriers (ATP), signaling molecules (cyclic nucleotides), and cofactors (NAD+, FAD). The biosynthesis of nucleotides is a complex process that involves the synthesis of the purine or pyrimidine bases, the addition of sugar and phosphate groups, and the assembly of the nucleotide triphosphates. The biosynthetic pathways for purinesand pyrimidines are distinct and involve multiple enzymatic reactions and regulatory steps. For example, the biosynthesis of purines, such as adenine and guanine, starts with the synthesis of inosine monophosphate (IMP) from ribose-5-phosphate and amino acids such as glycine and glutamine, via a series of reactions catalyzed by enzymes such as PRPP synthase, adenylosuccinate synthase, and adenylosuccinate lyase.Carbohydrate BiosynthesisCarbohydrates are the primary source of energy for many organisms, including humans. Carbohydrates also serve as structural components of cell walls, extracellular matrix, and glycoproteins. The biosynthesis of carbohydrates involves the conversion of simple sugars such as glucose, fructose, and galactose into more complex polysaccharides through a series of condensation and glycosylation reactions. The biosynthetic pathways for carbohydrates are highly regulated and coordinated, involving enzymes such as hexokinase, phosphofructokinase, and glycogen synthase.Lipid BiosynthesisLipids are a diverse group of molecules that serve many functions in living organisms, including energy storage, membrane structure, signaling, and insulation. The biosynthesis of lipids involves the synthesis of fatty acids, which are then assembled into triglycerides, phospholipids, and other lipid classes. The biosynthetic pathway for fatty acids involves the conversion of acetyl-CoA into malonyl-CoA, which is then used as the building block for fatty acid synthesis. The synthesis of fatty acids is catalyzed by the enzyme fatty acid synthase, which is composed of several subunits that work together to synthesize the fatty acid chain.ConclusionBiosynthesis and biosynthetic pathways are essential processes that contribute to the diversity and complexity of living organisms. These processes involve the utilization of simple precursors such as glucose, amino acids, and nucleotides to synthesize complex organic molecules such as proteins, DNA, and lipids. The biosynthetic pathways for these molecules are highly regulated and controlled, involving multiple enzymatic reactions,intermediates, and regulatory molecules. Understanding the biosynthesis of these molecules is critical for developing new drugs, designing enzymes, and engineering biological systems.。

Vol 42No 4Dec2020第42卷第4期2020年12月延 边 大 学 农 学 学 报AgriculturalScienceJournalofYanbian University 文章编号：1004-7999(2020)04-0008-09 DOI :10. 13478/j. cnki jasyu. 2020. 04. 002基于转录组测序的两种猪苓菌丝体多糖代谢途径比较分析任洁，李太元，李艳茹，梁运江，许广波*(延边大学农学院，吉林延吉133000)摘要：以长白山猪苓菌丝体和陕西猪苓菌丝体为研究材料进行转录组测序，分析猪苓多糖生物合成的代谢途径，初步探讨其参与代谢过程的表达差异基因。

通过对转录组原始数据进行数据质控共得到20 999个Un-gene 。

长白山猪苓与陕西猪苓菌丝体相比共有5 881个表达差异基因，长白山猪苓菌丝体上调表达的基因有 2 616个，下调表达基因有3 265个。

在氨基糖与核苷酸糖代谢通路中共涉及到28个基因产物，与其相关的Unigene 共有49条，有13条差异基因参与到8个基因产物的代谢过程。

在果糖与甘露糖代谢相关的Unigene共有28个,涉及到20个基因产物，有4条差异基因参与到8个基因产物的代谢过程。

该研究为今后深入开展猪苓多糖代谢途径及相关功能基因等研究提供了基本数据。

关键词：猪苓菌丝体;转录组；功能注释；糖代谢途径中图分类号：R284. 1文献标识码：AStudy on fructose and mannose metabolism pathway of two kind mycelia ofPolypous umbellatus based on transcriptome sequencingREN Jie , LI Taiyuan , LI Yanru , LIANG Yunjiang , XU Guangbo *{Agricultural College of Yanbian University 犢anji Jiiin 133002, China )Abstract : The transcriptome sequencing was carried out to analyze the metabolic pathways of polysaccha-ridebiosynthesisin myceliaof Polyporusumbe l atus from ChangbaiMountainandShaanxiProvince ，andthedi f erentia l yexpressedgenesinvolvedinthemetabolicprocesswerepreliminarilydiscussed Atotalof20999unigeneswereobtainedbyqualitycontroloftranscriptomerawdata Therewere5881di f erential- lyexpressed genesbetweenthe mycelium of Polyporusumbe l atus in Changbai Mountain and that in Shaanxi ， 2616genes wereup-regulatedand3265genes weredown-regulatedinthe mycelium of Pol- yporusumbe l atus in Changbai Mountain A total of 28 gene products were involved in the amino sugarandnucleotidesugarmetabolicpathway ， and49unigenesassociatedwiththem Inaddition ， 13di f erential geneswereinvolvedinthemetabolicprocessof8geneproducts Therewere28unigenesrelatedtofruc-toseand mannose metabolism ， involving20geneproducts ， and 4 di f erential genes were involved in the metabolicprocessof8geneproducts Thisstudyprovidesbasicdataforfurtherresearchon Polyporusumbe l atus polysaccharidemetabolicpathwayandrelatedfunctionalgenes收稿日期：2020-10-15基金项目：国家自然科学基金项目（81960686； 31160014）作者简介：任洁（1995—）,女，山西长治人，在读硕士，研究方向为食药用真菌学。

Thyroid Hormone Receptor␤(TR␤)and Liver X Receptor (LXR)Regulate Carbohydrate-response Element-binding Protein(ChREBP)Expression in a Tissue-selective Manner*□S Received for publication,May19,2010,and in revised form,June24,2010Published,JBC Papers in Press,July8,2010,DOI10.1074/jbc.M110.146241Karine Gauthier‡1,2,Cyrielle Billon‡1,Marie Bissler‡,Michel Beylot§,Jean-Marc Lobaccaro¶,Jean-Marc Vanacker‡, and Jacques Samarut‡From the‡Institut de Ge´nomique Fonctionnelle de Lyon,Universite´de Lyon,Universite´Lyon1,CNRS,INRA,Ecole Normale Supe´rieure de Lyon,46alle´e d’Italie,69364Lyon,France,§Inserm ERI22/EA4173,Faculte´Rockefeller,Universite´Lyon1,69373Lyon,France,and the¶UMR,CNRS6247,Clermont Universite´,Centre de Recherche en Nutrition Humaine d’Auvergne, 63177Aubie`re Cedex,FranceThyroid hormone(TR)and liver X(LXR)receptors are tran-scription factors involved in lipogenesis.Both receptors rec-ognize the same consensus DNA-response element in vitro.It was previously shown that their signaling pathways interact in the control of cholesterol elimination in the liver.In the present study,carbohydrate-response element-binding pro-tein(ChREBP),a major transcription factor controlling the activation of glucose-induced lipogenesis in liver,is charac-terized as a direct target of thyroid hormones(TH)in liver and white adipose tissue(WAT),the two main lipogenic tis-sues in ing genetic and molecular approaches, ChREBP is shown to be specifically regulated by TR␤but not by TR␣in vivo,even in WAT where both TR isoforms are expressed.However,this isotype specificity is not found in vitro.This TR␤specific regulation correlates with the loss of TH-induced lipogenesis in TR␤؊/؊mice.Fasting/refeeding experiments show that TR␤is not required for the activation of ChREBP expression particularly marked in WAT following refeeding.However,TH can stimulate ChREBP expression in WAT even under fasting conditions,suggesting completely independent pathways.Because ChREBP has been described as an LXR target,the interaction of LXR and TR␤in ChREBP regulation was assayed both in vitro and in vivo.Each recep-tor recognizes a different response element on the ChREBP promoter,located only8bp apart.There is a cross-talk between LXR and TR␤signaling on the ChREBP promoter in liver but not in WAT where LXR does not regulate ChREBP expression.The molecular basis for this cross-talk has been determined in in vitro systems.De novo lipogenesis allows the synthesis of new molecules of fatty acids from acetyl CoA.High glucose and insulin concen-trations induce this process,converting the excess energy into triglycerides,a more relevant molecule for storage purposes.In rodents,both liver and WAT3are efficient sites for lipogenesis. The synergic actions of insulin and glucose on the expression of lipogenic genes are mediated by key transcription factors. Insulin acts mainly through SREBP(sterol regulatory element-binding protein)-1c(1),whereas carbohydrate-response ele-ment-binding protein(ChREBP)is the master factor for glu-cose-induced lipogenesis(2).ChREBP physiological function has mainly been studied in the liver.ChREBPϪ/Ϫmice display a diminution in both basal and glucose-induced liver fatty acid synthesis due to the decreased expression of ChREBP glycolytic and lipogenic targets(3).Most interestingly,the ChREBPϪ/Ϫmutation protects Ob/Ob mice from obesity and reduces their plasma glucose level(4),suggesting that inhibition of ChREBP might be of pharmacological interest to treat the metabolic syndrome.ChREBP is expressed in many other tissues including WAT,where its possible lipo-genic role is presently unclear.ChREBP activity is mainly regulated by post-translational modifications that control its relocation to the nucleus and its DNA binding activity(5).When active,ChREBP turns on the expression of genes harboring a ChoRE(carbohydrate-re-sponse element)in their promoters.All the genes encoding the enzymes involved in lipogenesis(FAS,ACC,SCD1,L-PK, G6PD,ME,and Spot14)are direct ChREBP targets.During fast-ing,ChREBP is inactivated and located in the cytoplasm.In contrast ChREBP mRNA level varies in a narrow range.In liver, its level doubles when animals are switched from a fasted to a fed state(6).A similar up-regulation of its expression can be observed in mouse and human hepatocytes exposed to a high glucose concentration(7).In3T3-L1cells,insulin,glucose,and fatty acids regulate ChREBP expression(8).In contrast to liver, ChREBP mRNA is very efficiently induced(10-fold)following refeeding in WAT(6,8).The physiological consequence of this regulation in WAT remains unknown.*This work was supported by SIGNATOR Grant ANR-06-BLAN-0232-01,Cre-scendo Contract LSHM-CT-2005-018652,Cascade,Contract FOOD-CT-2004-506319,the Fondation pour la Recherche Me´dicale Grant INE2000-407031/1,and the Fondation BNP-Paribas.□S The on-line version of this article(available at )contains supplemental Table1and Figs.1–3.1Both authors contributed equally to this work.2To whom correspondence should be addressed:IGFL,UMR5242,ENS de Lyon,46alle´e d’Italie,69364Lyon cedex07,France.Tel.:33-0-472728616;Fax:33-0-472728080;E-mail:kgauthie@ens-lyon.fr.3The abbreviations used are:WAT,white adipose tissue;LXR,liver X receptor;RXR,retinoid X receptor;LXRE,LXR-response element;ChREBP,carbohy-drate-response element-binding protein;SREBP,sterol regulatory ele-ment-binding protein;TH,thyroid hormones;TR,thyroid hormonereceptor;TRE,TH-response elements;FAS,fatty acid synthase;PTU,propyl-thiouracil;qRT-PCR,quantitative RT-PCR;m,mouse;h,human.THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL.285,NO.36,pp.28156–28163,September3,2010©2010by The American Society for Biochemistry and Molecular Biology,Inc.Printed in the U.S.A.at Karolinska institutet library, on February 16, Downloaded from/content/suppl/2010/07/08/M110.146241.DC1.html Supplemental Material can be found at:Thyroid hormones(TH)up-regulate lipogenesis in liver,but their roles in WAT are controversial(9–11).Their actions are mediated by the TR␣and TR␤nuclear receptors,which act as transcription factors by binding to specific TH-response ele-ments(TRE)as homodimers or heterodimers with the nuclear receptor RXR(12).Several genes involved in lipogenesis such as FAS,ACC,Spot14,or ME are positively regulated by TH in liver (13,14).TRE have been identified in some but not all of their promoters.The expression patterns of TR␣and TR␤are only partially overlapping(15).In liver,TR␤represents80%of the TH-bound TR(16),whereas in WAT,both receptors are highly expressed.The phenotyping of different TR KO mice sheds light on the role of each isotype in mediating TH signal(12,17). Importantly in the organs where they are co-expressed,their function is not necessarily redundant.Recently,two genes were described to be specifically regulated by either TR␣1or TR␤(18)in the outer hair of the developing cochlea,suggesting that each receptor might regulate its own set of targets in response to TH.The lipogenic effect of TH has been attributed to TR␤because in the liver,TH regulation of FAS,ACC,Spot14,and ME is lost in TR␤Ϫ/Ϫmice(13).However,because TR␣is weakly expressed in this tissue,liver might not be the most appropriate tissue to assay isotype specificity.The LXR nuclear receptors could be involved in the lipogenic action of TR.Dif-ferent levels of potential cross-talk between LXRs and TR␤have indeed been described(19).For instance,LXR␣expres-sion has been previously described to be regulated by TH in mouse liver(20).At a functional level,LXRs and TR␤regulate a common set of events especially in the liver,where both recep-tors stimulate lipogenesis and cholesterol disposal.From a molecular point of view,these receptors can bind to identical (DR4)elements in vitro,although only one of these elements(in the cyp7a1gene promoter)has been characterized as a com-mon LXR-and TR-response element(21).Interestingly,LXRs were recently shown to directly control ChREBP expression by binding to a DR4element in its promoter(22).Another DR4 element located in the near vicinity was shown to mediate the positive effect of TH on ChREBP expression in the mouse liver (23).In this study,we show that TH directly activate ChREBP not only in liver(23)but also,to a higher extent,in WAT.In vivo, this effect is TR␤-,but not TR␣-,dependent,although both TR isoforms are strongly expressed in WAT,whereas in vitro,both isoforms can drive the expression of a reporter gene down-stream of the ChREBP promoter and bind to the same response element.Despite its capacity to up-regulate ChREBP expres-sion,TR␤is not required for ChREBP induction in response to the fasting/refeeding protocol.TR␤acts independently of LXR. Finally,although ligands for these receptors could co-regulate the ChREBP promoter in liver,different approaches point out to a mutually exclusive binding of LXR and TR to this promoter. EXPERIMENTAL PROCEDURESPlasmids—The expression plasmids were all pSG5-based vectors(mouse TR␣,rat TR␤1,mouse RXR␣,and mouse LXR␣).The different promoters were cloned in the pGL3basic vector and/or PGL4.70(hRluc)(Promega,Charbonnie`res, France).The3kbp upstream of the mouse ChREBP transcrip-tion start site were amplified by PCR using the primers ChREBPprom,cloned in pGL3basic/PGL4.70(pChREBP).The mutants(pM1,pM2,and pM1M2)were obtained using site-directed PCR mutagenesis(with M1and M2primer pairs).All plasmids were sequenced(Cogenics Genome Express,Meylan, France).Chemicals—Tri-iodothyronine(T3)and thyroxine(T4)were from Sigma-Aldrich(l’Isle D’Abeau,France),and the synthetic LXR ligand T0901317(T09)was from Cayman Chemical (Montigny le Bretonneux,France).Animals and Preparation of Tissue Samples—Knock-out mice were in a C57black6:129sv mixed background.TR␤Ϫ/Ϫ, TR␣0/0(17,24,25),LXR KO(26),and controls were fed ad libitum A04diet(SAFE,Augy,France),and housed under rec-ommended conditions.3–5-month-old male mice were used unless indicated otherwise.TH deficiency in adult animals was induced as described with a PTU-containing diet(Harlan Tek-lad TD95125,Madison,WI)and followed or not by TH(mix of T4and T3)injection(13).T09was given by oral gavage once a day for3days(10mg/kg of T09in100␮l of methyl cellulose 1%).Pax8Ϫ/Ϫmice,which are genetically hypothyroid,were previously described to die before weaning(27);however,some spontaneously survived.These rare survivors were used for experiments.For the fasting/refeeding protocol,mice fed a reg-ular chow diet were fasted for24h and either refed a70%high carbohydrate diet(Harlan Teklad TD98090)or kept on fasting for an additional16h.Tissues were dissected immediately after cervical dislocation and flash-frozen in liquid nitrogen.For WAT ex vivo culture,peritesticular fat pads were dissected and cultured non-dilacerated in10%charcoal-stripped fetal bovine serum(FBS),5ng/ml insulin complemented DMEM(Invitro-gen,Cergy-Pontoise,France)for24h before the addition of ligands.All animal experiments were performed under animal care procedures and conducted in accordance with the guide-lines set by the European Community Council Directives (86/609/EEC).RNA Extraction and Expression Analyses by Relative Quan-titative RT-PCR(qRT-PCR)—RNAs were extracted using TRIzol(Invitrogen).Total RNA was converted to cDNA using the SuperScript II retrotranscription kit(Invitrogen).qRT-PCR analyses were performed using the Quantitect SYBR Green PCR kit(Qiagen,Courtaboeuf,France)on a Stratagene machine MX3000pro(Stratagene,La Jolla,CA).Duplicates were run for each sample.The results were analyzed accord-ing to the⌬⌬CT method(28).36B4was always used as the reference gene,and the control group was either the non-treated cells or the WT non-injected animals unless otherwise indicated.Cell Culture and Transient Transfection Assays—HeLa (ATCC-CCL2)and3T3-L1(ATCC-CL-173)cells were main-tained in DMEM supplemented with10%FBS(Invitrogen).For 3T3-L1,cells were induced to differentiate using insulin-dexa-methasone-Rosiglitazone mix.To observe a better response to T3,cells were switched to DMEM medium supplemented with 10%charcoal-stripped FBS before the experiments.T3was used at10Ϫ8M,and T09was used at10Ϫ5M.Cells were har-vested24h(ChIP or WAT explants)or36h(transient trans-fection assay)after ligand exposure.For transient transfections,TR␤and LXR Regulate ChREBP in a Tissue-selective Mannerat Karolinska institutet library, on February 16, Downloaded fromHeLa cells were seeded in24-well plates and transfected with ExGen(Euromedex,Souffelweyersheim,France)following the manufacturer’s recommendations and0.5␮g of final DNA. pSG5was added as a carrier when needed.Transfection effi-ciency was normalized using␤-Gal activity brought by co-transfection of CMV␤-Gal vector.For each experiment,tripli-cates of each conditions were done,and each experiment was repeated at least three times,giving similar results.Only one experiment is shown;each point represents the average for the triplicate,and the error bar represents their S.D.Chromatin Immunoprecipitation Assays—The anti-TR␣an-tibody was raised against a C-terminal peptide and affinity-purified with the same peptide;the anti-TR␤(TR-J52)and con-trol IgG(normal mouse IgG)antibodies were purchased from Santa Cruz Biotechnology,and the anti-RNA polymerase II (CTD4H8)from Upstate Biotech Millipore.Cells were cross-linked with1%formaldehyde before lysis(in1%SDS,10m M EDTA,50m M Tris-HCL,pH8.1)and sonication(200–700bp DNA fragments).Lysates were diluted and precleared with her-ring sperm DNA(2␮g/ml),BSA(2␮g/ml),mouse IgG,and protein G-Sepharose(GE Healthcare,Saint-Cyr au Mont d’or, France).Lysates were incubated with the cognate specific anti-bodies or IgG and protein G-Sepharose.Beads were washed and eluted.Cross-link was reversed by overnight incubation at 65°C in the presence of RNase A and200m M NaCl.Samples were purified(Qiagen)and analyzed by quantitative PCR using the primer pairs NS1,NS2,and S1.EMSA—mTR␣1,mTR␤,mLXR␣,and mRXR␣were in vitro translated(T N T kit,Promega).The different single-strand oli-gonucleotides(forward)were[␥-32P]ATP-labeled with T4 polynucleotide kinase(Fermentas,Burlington,Ontario)before annealing with their unlabeled antisense(reverse).Probes were purified and counted.20,000cpm were used for each bindingreaction.Unlabeled specific and nonspecific competitor probes were included at the indicated molar excess.Hepatic Lipogenesis—Mice were given an i.p.injection of deuterated water(10ml/kg in0.9%NaCl isotonic water)fol-lowed by administration of drinking water enriched with deu-terated water(3%v/v)ad libitum for24h.Plasma was then collected for the measurement of deuterium enrichment in plasma water and in the palmitate of plasma triglycerides as described previously(29).These enrichments were then used to calculate the contribution,expressed as percentage,of hepatic lipogenesis to the plasma triglyceride pool(30). Statistics—For mice experiments,the data presented repre-sent the average values for the different animals(4or5)from the same genotype given the same treatment.The error bars represent S.E.Statistical relevance was determined using the one-variable analysis of variance method.All the primer sequences are listed in supplemental Table1.RESULTSChREBP Expression Is Regulated by TH in the Different Lipo-genic Tissues in a TR␤-dependent Manner—ChREBP expres-sion was recently shown to be regulated by TH in the liver of C57/BL6mice treated with PTU/Methimazole(23).Here the regulation of ChREBP was studied in the pax8(deprived of thyroid)mutant mice and Sv129mice treated with PTU(Fig.1A).In both models,TH injection induced ChREBP mRNA level in WAT and to a lesser extent in liver.Consistently,the expression of FAS(a target of both TRs and ChREBP)and L-PK (a ChREBP-only target gene)was also enhanced by TH,sug-gesting that ChREBP activity(and not only expression)is also up-modulated by TH.The TH-induced regulation of ChREBP was lost in TR␤Ϫ/Ϫbut not TR␣0/0mice,indicating that TR␤was required at least in the two metabolic tissues studied(Fig. 1B)despite the strong expression of TR␣in WAT.The critical role of TR␤for TH-induced hepatic lipogenesis was demon-strated in vivo using wild-type(WT)and TR␤Ϫ/ϪPTU-treated male mice.Although TH efficiently increased lipogenesis in WT(Fig.1C),the response was blunted in TR␤Ϫ/Ϫmice.WAT lipogenesis was not measured due to technical limitations. TH/TR␤and Nutritional Status,Two Independent Ways to Regulate ChREBP expression—To determine the involvement of TH signaling in the physiological regulation of ChREBP expression,RNA level was assessed in liver and WAT in response to a fasting/refeeding protocol in both WT and TR␤Ϫ/Ϫmice(Fig.2A).In agreement with published data, ChREBP RNA was found only up-regulated2-fold in the liver (6).In contrast,a dramatic increase of its expression was observed in WAT upon refeeding.This response was also observed in TR␤Ϫ/Ϫmice,indicating that TR␤is not required for this physiological process.We next determined whether FIGURE1.ChREBP expression and lipogenesis are regulated by thyroid hormones in a TR␤-dependent manner.3-month-old males either genetically rendered(pax8Ϫ/Ϫ)or chemically rendered(WT,TR␤Ϫ/Ϫ,TR␣0/0-PTU treated)hypothyroid were injected either by PBS(white bars)or by TH (black bars).In A and B,nϭ4for higher panel,nϭ5for lower panel(A)and (nϭ5)(B),mRNA encoding lipogenic enzymes were quantified by qRT-PCR. Veh,vehicle.In C,liver lipogenesis was measured as described under“Exper-imental Procedures”(nϭ5).Results are shown as induction as compared with the PTU-treated animals of a given genotype.Error bars represent S.E.Aster-isks and dollar signs indicate respectively statistical significance as compared with the PTU treatment of the same genotype and to the equivalent treat-ment in the WT group($or*,pՅ0.05,$$or**,pՅ0.005,$$$or***, pՅ0.0005).TR␤and LXR Regulate ChREBP in a Tissue-selective Mannerat Karolinska institutet library, on February 16, Downloaded fromChREBP expression could be TH-regulated under all nutri-tional conditions.ChREBP,as well as FAS and Spot14mRNAs, were induced by TH in the fasted(non-lipogenic)conditions in WAT(Fig.2B).In contrast,TH failed to significantly activate these genes when mice were refed.This might be due to an already high ChREBP expression under these conditions.In the liver,the extent of ChREBP mRNA regulation is much more limited,and in contrast to WAT,the nutrition signal is domi-nant,blocking a potential effect of TH on the three target genes in the fasted state.TR␤Binds to and Activates ChREBP Promoter via the Previ-ously Described LXRE2—The results presented above identified TH/TR␤as a new way to modulate ChREBP expression in vivo. The mechanisms responsible for this regulation were then investigated in vitro.In contrast to what was observed in vivo, TR␤,but also TR␣,when co-expressed with RXR␣,was able to activate the3.2-kbp ChREBP proximal promoter(Fig.3A)in the presence of TH(Fig.3B).LXR␣,previously described to activate this same portion of the promoter(22),was used as a positive control.Two DR4elements(LXRE1and LXRE2)were described in the mouse ChREBP promoter,with LXRE1being involved for LXR response(22)and LXRE2being necessary for TH response(23).These binding specificities were confirmed here by the EMSA data(Fig.3C).All three receptors bound to a 44-bp probe encompassing the two LXREs.However,LXR binding was competed only by an LXRE1WT but not mutated probe,whereas TR␤1or TR␣binding was only competed by an LXRE2WT but not mutated probe.The dependence on these sites for transcriptional responsiveness to either TR or LXR was less obvious in the transfection assay(Fig.3B).The double M1M2mutant still showed responsiveness to both compounds. This apparent discrepancy with EMSA results and published data for TR(23)is likely due to the inability of the four point mutations introduced in each promoter construct to efficiently prevent TR binding.For LXR,Cha and Repa(22)actually also observed a residual induction of similar pM1and pM1M2con-structs by the LXR agonist T09.This suggests either that besides LXRE1,some other region(s)of the promoter could mediate the response to LXR or that as for TR,the mutations introduced in LXRE1are not disruptive enough.ChIP experiments were performed to investigate the molec-ular mechanisms underlying the TR isoform specificity in the regulation of the endogenous ChREBP promoter.Differenti-ated3T3L1adipocytes in which ChREBP mRNA is also induced by TH were used.Similar to WAT,these cells express both TR␣and TR␤(31).Both TRs were detected on the region containing the LXREs but not on the upstream or downstream promoter regions.TR binding was independent of T3in agreement with the accepted model for TR action.In contrast,RNA polymerase II was enriched at the transcriptional start site only in the pres-ence of T3(Fig.3D).Altogether,these data clearly demonstrate that both TR␣and TR␤bind to the LXRE2in the ChREBP promoter and allow its induction in the presence of T3at least in a reporter system.Cross-talk between TR␤and LXR Signaling for the Regulation of ChREBP Expression—Published work described the LXR␣gene as a TH target in mouse liver(20).In the present study,no significant regulation of LXR␣expression by TH or T3was detected in the different models and experiments performed (Fig.4,A and D).Furthermore,TH was capable of activating the expression of ChREBP as well as other lipogenic genes in the liver of PTU-treated LXR KO mice(Fig.4A).The induction of ChREBP expression by TH is thus LXR-independent.TR␤and LXR activate the ChREBP promoter by respectively binding to LXRE2and LXRE1,two elements located in the close vicinity of each other.We thus assayed a potential functional interaction between the two signaling pathways.In liver but not in WAT, TH induction of ChREBP expression was significantly higher in LXR KO mice than in WT(4.5-fold versus2.9-fold,respectively, Fig.4A),suggesting that LXR might limit TR␤access to the promoter in WT liver.Such an increase is not observed for the regulation of other genes such as FAS,which is known to be regulated by both pathways.To document this interference for promoter binding,transfection experiments were performed in the presence of non-limiting amounts of RXR.Transfected alone,TR␤or LXR induced pChREBP activity in the presence of their cognate ligands(respectively,TH and T09).Remark-ably,co-transfection of both decreased the response to each ligand,LXR-dependent activity being more affected than TR (Fig.4B,left panel)by this inhibition.T09and T3displayed additive effects when both receptors were present.These obser-vations support the fact that concomitant binding of the two receptors to a single ChREBP promoter does not occur.This mutual inhibition was also observed to a lesser extent for both TR and LXR activities when increasing amounts of the other receptor were added.(Fig.4B,right panel).Finally direct evi-dences for a mutually exclusive binding were obtained by EMSA experiments.As shown previously in Fig.3,both recep-tors bind as RXR heterodimers to a44-mer probe containing the two WT LXREs.These two complexes migrated at the dif-FIGURE2.Independent regulation of ChREBP expression by TH/TR␤andnutritional status.WT and TR␤Ϫ/Ϫ3-month-old male mice were submittedto modification of nutritional and/or TH status.In A,mice were either fed aregular chow diet(CF)or starved for24h and then refed(R)or not(F).(nϭ5).In B,mice were starved for24h.One group was kept on fasting(F),and theother one was refed(R)for an additional16h.Half of the animals per groupwere injected by TH twice,once before the fast and then before the refeeding(nϭ5).Expression of lipogenic genes was measured by qRT-PCR.Asterisksindicate statistical significance(*,pՅ0.05,**,pՅ0.005,***,pՅ0.0005)ascompared with the CF group of the same genotype in A,to the F/V group in B).Dollar signs indicate statistical significance between F and RF groups in A andbridged groups in B($,pՅ0.05,$$,pՅ0.005,$$$,pՅ0.0005).In A,the valuefor the relative expression has been fixed to one in each genotype for the CFgroup.Error bars represent S.E.TR␤and LXR Regulate ChREBP in a Tissue-selective Mannerat Karolinska institutet library, on February 16, Downloaded fromferent sizes indicated on the figure.The LXR/RXR complex bound to the WT probe was gradually displaced by an increas-ing amount of TR ␤/RXR,which noticeably failed to bind theprobe even at the highest amount added.We also observed that a TR ␤/RXR complex was displaced by the addition of LXR/RXR.However,in both cases,the newly added complex was perfectly able to bind in a dose-dependent manner if the probe used contained a mutated version of the LXRE required for the fixation of the initially present receptor (M1for LXR and M2for TR).Altogether,these data strongly suggest that despite using two different LXREs,in this in vitro setting,concomitant binding of LXR/RXR and TR/RXR to the ChREBP promoter fragment is prevented.As a complementary way to analyze the interference between LXR and TR signaling pathways,mice or WAT explants were treated with different combinations of LXR and TR ligands (Fig.4D ).The efficiency of the different treatments was val-idated by measuring the expression levels of known LXR or TR targets in the two considered systems.In WAT explants,all genes behaved as expected with strong induction of ABCA1,SREBP1c,and ApoE by T09,whereas ChREBP and FAS were stimulated by T3.Surprisingly,in these same samples,LXR ligand failed to induce ChREBP expres-sion.Co-treatment with both ligands did not yield any additional effect as compared with treatment with individual ligand for any of the target tested.This suggests that TR and LXR mainly possess a non-over-lapping set of targets in WAT.In liver,treatments were also efficient,with an increase of both ChREBP and FAS by TR and LXR ligand alone.In this condition,ChREBP induction by T09does not reach statistical significance,but lack of strong induction has already been described by others (32).Co-treatment with T09and TH led to a significant increase inChREBP as well as FAS liver expres-sion as compared with TH treat-ment alone.This suggests that the two signals can be additive in this organ.For SREBP1-c and ABCA1,the situation is more complex.In PTU-treated mice,no activation was detected by T09alone,and TH repressed expression of both genes.Nonetheless,T09strongly in-creased their expression in TH-treated animals.Altogether,these data demonstrate that TR ␤and LXR are both active in the two lipo-genic tissues,WAT and liver,although their target genes are different in vivo and depend on the tissue considered.DISCUSSION In this report,we show that in mice,ChREBP is a new direct TH target not only in liver,which is in agreement with recently published data (23),but also to a much higher extent in WAT.Careful dissection of the molecular mechanism of ChREBP reg-ulation allowed us to demonstrate that TR ␤,but not TR ␣,is required for this activity in vivo and interferes with LXR signaling.TH Stimulate ChREBP Expression in a TR ␤-dependent Man-ner in Liver and WAT —TH have been long known to regulate energy metabolism and lipogenesis in the liver (9–11),yet their lipogenic effect in other tissues such as WAT was still contro-versial.Measurement of in vivo hepatic lipogenesis demon-strates that TH induction of this process is TR ␤-mediated because it was abrogated in TR ␤Ϫ/Ϫ.Notably,this regulation by TR ␤correlates with its ability to up-regulate ChREBP expres-FIGURE 3.TR ␣and TR ␤bind to and activate ChREBP promoter via the previously described LXRE2.A ,scheme of the different versions of the ChREBP promoter cloned upstream of a luciferase reporter.LXRE1and LXRE2are pictured as black ovals or white when mutated.The top arrow indicates the transcription start site.The arrow pairs below the promoter indicate the localization of the primers used for ChIP analyzes:white for NS2,black for S1,and gray for NS1.The regions amplified by these three pairs are respectively the promoterportion Ϫ4100/Ϫ3900,Ϫ2558/Ϫ2384,and Ϫ203/ϩ4.B ,the indicated promoters were transfected with TR ␣,TR ␤,or LXR ␣together with an RXR ␣encoding plasmid and treated with vehicle (veh ,white ),T3(light gray ),or T09(dark gray ).The relative luciferase activity measured is reported as arbitrary units (RAU ).C ,EMSA wereperformed using a 44-bp-long probe from the ChREBP promoter (WT probe)containing the area with the twoLXREs to detect TR ␤/RXR ␣or TR ␣/RXR ␣binding.LXR ␣/RXR ␣has been included as a control.The asterisks indicate the specific petition with 100-fold excess of cold smaller fragments containing only one of the two LXREs,either WT (LXRE1or LXRE2)or mutated (LXRE1mut or LXRE2mut),was used to assess thespecificity of the binding.mut ,mutation.D ,ChIP experiments were performed on differentiated 3T3-L1,treated (light gray )or not (white )with T3.On the left are results obtained with anti-TR ␣(TR ␣),anti-TR ␤(TR ␤),or mouse IgG (IgG ).On the right are results obtained with anti-RNA polymerase II (RPII )and mouse IgG (IgG ).The specificity of the antibodies (Ab )used was verified on transfected HeLa cells (supplemental Fig.1).The samelysates were used for all conditions,and each precipitation was done in replicates.The results shown are an average of these duplicates.Each experiment has been repeated at least twice.The primer pairs used for detection are indicated under the arrows .Error bars represent S.D.TR ␤and LXR Regulate ChREBP in a Tissue-selective Mannerat Karolinska institutet library, on February 16, 2011 Downloaded from。

170中华临床营养杂志2020 年6 月第28 卷第3 期Chinese Journal of Clinical N u丨rition，June 2020，V〇1.28，N〇.3•论著•二甲双胍对2型糖尿病合并肥胖患者肠道细菌群落结构和功能的影响邢英郑嵘炅姜春晖玛依拉•卡哈尔木胡牙提新疆医科大学第一附属医院综合内四科，乌鲁木齐830000通信作者：木胡牙提，E-m a i l:m u h u y a t i@163.c o m【摘要】目的探究二甲双胍对2型糖尿病合并肥胖患者肠道细菌群落结构和功能的影响。

方法选取2型糖尿病合并肥胖患者30例，借助高通量测序手段比较二甲双胍治疗前后肠道菌群多样性、群落结构和功能的差异。

结果二甲双胍能够显著增加肠道菌群群落多样性和丰富度，调节肠道菌群群落结构，增强氨基酸代谢、碳水化合物代谢、脂质代谢、丙酸代谢和丁酸代谢等多种代谢功能，同时显著抑制2型糖尿病、胰岛素抵抗以及胰高血糖素信号通路等功能基因的表达。

结论二甲双胍可通过影响肠道菌群结构和功能参与降糖过程。

【关键词】2型糖尿病；肠道菌群；二甲双胍基金项目：新疆维吾尔自治区自然科学基金（2017D01C343)DOI ：10.3760/cma. j. cn 115822- 20200601-00139Effects of metformin on intestinal bacterial community structure and function in obese patients withtype 2 diabetes mellitusXing Ying, Zheng Rongjiong, Jiang Chunhui, Mayila •kahaer, MuhuyatiDepartment of Endocrinology .Xinjiang Medical University First Affiliated Hospital yVrumqi 830000, ChinaCorresponding author：Muhuyati, E-mail：mu\\uya.\\@ 【Abstract】Objective To explore the effect of metformin on intestinal bacterial community structure andfunction in obese patients with type 2 diabetes mellitus. Method Thirty obese patients with type 2 diabetesm ellitus were selected to compare the differences of intestinal flora diversity, community structure and functionbefore and after metformin treatm ent by means of high-throughput sequencing. Result Metformin could signifi­cantly increase the diversity and richness of intestinal flora comm unity, regulate the structure of intestinal floracom m unity, enhance a variety of metabolism functions such as amino acid m etabolism, carbohydrate metabo­lism, lipid m etabolism, propanoic acid metabolism and butanoate metabolism, and significantly inhibit the ex­pression of functional genes such as type 2diabetes m ellitus, insulin resistance and glucagon signaling pathway.Conclusion Metformin can participate in the hypoglycemic process by affecting the structure and function ofintestinal flora.【Key words】Type 2 diabetes m ellitus; Intestinal flora; MetforminFund program：Natural Science Fund of Xinjiang Uygur Autonomous Region (2017D01C343)DOI ：10.3760/cm a. j. cn 115822- 20200601-00139肥胖与 2 型糖尿病（type 2 diabetes mellitus, T2D M)的发生发展具有密切联系[|]，肠道菌群作 为主导人体健康的关键参与者[2],影响宿主的营 养、代谢及免疫，在糖尿病、肥胖症等疾病中具有 重要贡献[34]。

任何学科的形成和发展，都与当时的科学技术水平。

经济建设要求以及相关学科的促进分不开的。

早期的药物化学以化学学科为主导，包括天然和合成药物的性质、制备方法和质量检测等内容。

随着科技发展，天然药物化学、合成药物化学和药物分析等学科相继建立。

现代药物化学是化学和生物学科相互渗透的综合性学科。

主要任务是创制新药、发现具有进一步研究开发前景的先导物。

研究内容主要有：基于生命科学研究揭示的药物作用靶点（受体、酶、离子通道、核酸等），参考天然配体或底物的结构特征。

设计药物新分子，以期发现选择性地作用于耙点的新药；通过各种途径和技术寻找先导物，如内源性活性物质的发掘，天然有效成分或现有药物的结构改造和优化，活性代谢物的发现等，其次计算机在药物研究中的应用日益广泛，计算机辅助药物设计（CADD）和构效关系也是药物化学的研究内容。

如今信息科学迅猛发展，利用各种数据库和信息技术，比如Reaxys，可广泛收集药物化学的文献资料，有利于扩展思路，开拓视野，丰富药物化学的内容。

药物化学既要研究化学药物的结构、性质和变化规律，又要了解药物用于人体的生理生化效应和毒副反应以及构效关系才能完成它的任务。

有人比喻，如果现代药物化学是一只鼎，那么支撑这只鼎的分别是化学、生物学科和计算机技术。

创制新药是涉及多学科。

多环节的探索性系统工程。

是集体研究的成果，基于药物化学首先要发现先导物，为后续学科研究提供物质基础，在研究过程中起着十分重要的作用，因此药物化学在药学科学领域处于带头学科的地位。

Burger的名著《药物化学》现已改为（药物化学与药物发现）（Medicinal Chemistry and Drug Discovery），以突出药物化学的任务是创制新药和发现先导物，从而达到促进医药工业发展，保护人类健康的目的。

80年代初诺氟沙星用于临床后医学教|育网搜集整理，迅速掀起喹诺酮类抗菌药的研究热潮，相继合成了一系列抗菌药物，这类抗菌药和一些新抗生素的问世，认为是合成抗菌药发展史上的重要里程碑。

褐藻多糖硫酸酯的研究进展马莉莎，张明（山东大学威海分校海洋学院，山东威海２“２０９）［关键词】褐藻多糖硫酸酯；海洋多糖［中图分类号］Ｒ９６１［文献标识码］Ａ［文章编号】１００２－２６６Ｘ（２００９）１１ｍ１１５－０２目前，对褐藻多糖硫酸酯的研究已经成为天然海洋药物开发的热点和主攻方向。

褐藻多糖硫酸酯具有多种生物活性，在抗肿瘤、抗凝血、抗病毒、抗炎症、抗氧化、降血糖、降血脂以及免疫调节等方向有着广阔的药用价值。

现将褐藻多糖硫酸酯的研究进展综述如下。

１主要来源及提取方法１．１主要来源褐藻多糖硫酸酯又称为褐藻糖胶、岩藻聚糖硫酸醺、岩藻聚糖等，是褐藻类海藻特有的化学组分，是褐藻类海藻细胞问的产物，目前可以提取褐藻多糖硫酸酯的主要原料有海带、海蕴、泡叶藻、裙带菜、羊栖菜、马尾藻、绳藻等，实现工业化生产的主要为前三者。

褐藻多糖硫酸酯的含量与植物部位有密切关系，海带叶片中的褐藻多糖硫酸酯含量比茎部多，且自基部向尖部逐渐增大；叶片边缘的褐藻多糖硫酸酯含量比中间部位多。

褐藻多糖硫酸酯的含量还随褐藻种属及生长时间变化，以７一１２月较高，３、４月较低。

１．２提取方法对海藻中的褐藻多糖硫酸酯分离提取方法有很多种，主要包括水提取法【４Ｊ、酸提取法”Ｊ、酶提取法【６Ｊ、溶剂萃取法１７ｌ、超声波提取法哺１等。

目前最常用的方法是酸提取法。

周裔彬等Ｈ１将海带干粉按１：２０加入０．１ｍ彬Ｌ盐酸在７５℃水浴中反应４ｈ，采用分级醇沉的方式得到不同品质的海带多糖，粗糖获得率达３５．１０％，纯化后的多糖含量达９６．６０％。

２分子结构特性属水溶性杂聚糖，主要组分是Ｌ褐藻糖４一硫酸酯，其他成分还包括半乳糖、甘露糖、木糖、葡萄糖、阿拉伯糖、糖醛酸及蛋白质、Ｋ＋、Ｎａ＋、Ｃａ２＋、Ｍ９２＋等金属离子，结构特征是ｃｌ，２－联结的聚仅・Ｌ吡喃褐藻糖，而硫酸酯主要是在ｃ４位的羟基上…。

ＫｙＨｎ在１９１３年首先报道褐藻多糖硫酸酯中含有。

岩藻糖。

Ｈｏａｇ—ｌａＭ和Ⅱｅｂ在１９１５年发现其中含有与钙结合的硫酸酯。

carbohydrate polymers,多糖相关的假设Carbohydrate Polymers: Exploring Hypotheses and Relevant ResearchIntroduction:Carbohydrate polymers, also known as glycans, play a crucial role in various biological processes, ranging from cell adhesion to energy storage. These complex molecules, composed of repeating sugar units, have sparked significant interest among researchers due to their unique properties and potential applications. In this article, we will delve into the realm of carbohydrate polymers, exploring hypotheses and discussing relevant research findings.The Structure and Function of Carbohydrate Polymers:Carbohydrate polymers exhibit a diverse range of structures, including linear, branched, and cross-linked forms. These structures are determined by the type and connectivity of sugar units present in the polymer chain. Depending on their composition, carbohydrate polymers can possess both hydrophilic and hydrophobic properties, rendering them versatile in various biological and industrial settings.One hypothesis surrounding carbohydrate polymers suggests that their structural diversity contributes to their ability to interact with specific biomolecules, such as proteins and lipids. These interactions can influence cellular processes, such as signaling pathways and immune responses. Research has shown that the arrangement and conformation of carbohydrate polymers can influence their binding affinity to specific receptors, thereby modulating biological outcomes.Characterization Techniques and Analytical Methods:To explore the properties and functions of carbohydrate polymers, scientists employ various characterization techniques and analytical methods. One commonly used method is nuclear magnetic resonance (NMR) spectroscopy, which allows for the determination of glycan structures and their conformational changes. By analyzing NMR spectra, researchers can elucidate the interactions between carbohydrate polymers and biomolecules.Another valuable analytical tool is mass spectrometry (MS), which provides information about the molecular weight, composition, and fragmentation patterns of carbohydrate polymers. MS analysis enables the identification and quantification of glycans in complex biological samples, aiding in the understanding of their roles in disease processes and physiological functions.Applications of Carbohydrate Polymers:The fascinating properties of carbohydrate polymers have led to their involvement in a wide range of applications. One significant area is the development of biomaterials for tissue engineering and drug delivery. Carbohydrate-based hydrogels, for example, have been explored as scaffolds for tissue regeneration due to their biocompatibility and ability to mimic the extracellular matrix.In the field of food science, carbohydrate polymers find utilization as stabilizers, thickeners, and emulsifiers. They enable the creation of desirable textures in processed foods and contribute to enhancing the storage stability of products. Moreover, their ability to form gels and films makescarbohydrate polymers valuable in food packaging, reducing the need for synthetic materials and minimizing environmental impact.Future Perspectives and Challenges:As researchers continue to explore carbohydrate polymers, several challenges and opportunities lie ahead. One hypothesis that requires further investigation is the potential role of carbohydrate polymers in modulating the gut microbiota. Emerging evidence suggests that these glycans may contribute to the diversity and functionality of gut bacteria, influencing overall health and disease outcomes.Additionally, the synthesis and production of carbohydrate polymers remain a significant challenge. Despite advances in biotechnology, large-scale production of complex glycans is still laborious and costly. Researchers are actively exploring enzymatic and chemoenzymatic methods to streamline production processes, making carbohydrate polymers more accessible for research and applications.Conclusion:The realm of carbohydrate polymers holds immense potential for scientific exploration and practical applications. Through innovative research and the examination of related hypotheses, scientists are unraveling the intricate roles of these polymers in biological systems. As we continue to unlock the mysteries of these compounds, carbohydrate polymers are poised to revolutionize diverse fields, including medicine, biotechnology, and food science.References:[Provide actual references here, without including any URL links]。