染色質(zhì)修飾及其作用機理

染色質(zhì)修飾及其作用機理DNAPackingDNA—2nm，核小體串珠—11nm，染色質(zhì)纖維—30nm，染色質(zhì)高級環(huán)狀結(jié)構(gòu)—300-700nm，間期染色體—1400-1500nm。染色質(zhì)的高級結(jié)構(gòu)

1.如何將10,000公里長的蠶絲(半徑~10-5米)裝入一個籃球中。

2.蠶絲的體積：3.14*10-3m3

3.折疊、纏繞…DNAPacking染色質(zhì)的高級結(jié)構(gòu)OrganizationofDNAWithinaCellfromLodish

etal.,MolecularCellBiology,6thed.Fig6-12metersofDNAispackedintoa10mmdiametercell核小體結(jié)構(gòu)染色質(zhì)模板2.8?的核小體模型（左），X射線晶體衍射核小體結(jié)構(gòu)（中），組蛋白核心八聚體被DNA盤繞結(jié)構(gòu)的圖示（右）。組蛋白尾部從核小體表面伸出。核小體結(jié)構(gòu)Histonevariants組蛋白修飾活化修飾：乙?；?，精氨酸甲基化，賴氨酸甲基化（H3K4，H3K36，H3K79）。抑制修飾：賴氨酸甲基化（H3K9，H3K27，H4K20）。組蛋白尾巴的修飾位點組蛋白修飾與修飾酶（1）組蛋白修飾與修飾酶（2）主要的功能基團AcetylMethylPhosphorylUbiquitinEpigeneticdifferences：monozygotictwins

DifferentialDNAmethylationbetweenMZtwinsusingAIMS.(ALeft)ExampleofanAIMSanalysisin3-and50-year-oldtwinpairs.DifferentialbandscorrespondingtoDNAmethylationareindicatedwitharrows.(ARight)NumberofdifferentialbandsobtainedbyAIMSin3-and50-year-oldtwinpairs.(B)

Bisulfitegenomicsequencingof12clonesoftherepetitiveDNAsequenceAlu-SPobtainedbyAIMSin3-and50-year-oldtwinpairs.SchematicrepresentationsofthemethylationstatusofeachCpG

dinucleotide.Blackandwhitedotsindicatemethylatedandunmethylated

CpGs,respectively.Epigeneticdifferences：monozygotictwins

MappingchromosomalregionswithdifferentialDNAmethylationinMZtwinsbyusingcomparativegenomichybridizationformethylatedDNA.Examplesofthehybridizationofchromosomes1,3,12,and17aredisplayed.The50-year-oldtwinpairshowsabundantchangesinthepatternofDNAmethylationobservedbythepresenceofgreenandredsignalsthatindicatehypermethylationandhypomethylationevents,whereasthe3-year-oldtwinshaveaverysimilardistributionofDNAmethylationindicatedbythepresenceoftheyellowcolorobtainedbyequalamountsofthegreenandreddyes.SignificantDNAmethylationchangesareindicatedasthickredandgreenblocksintheideograms.Epigeneticdifferences：monozygotictwins

(Upper)Quantificationofglobal5mCDNAcontent(Left),histoneH4acetylation(Center),andhistoneH3acetylation(Right)byHPLCandhigh-performancecapillaryelectrophoresis.(Lower)Comparisonofepigeneticvaluesbetweenthesiblingsofeach3-and50-year-oldtwinpair.FragaMF,

ProcNatl

Acad

SciUSA.2005,26;102(30):10604–10609內(nèi)容提要

一、組蛋白的乙?；?/p>

二、組蛋白的甲基化

三、組蛋白的磷酸化

四、組蛋白的泛素化

五、組蛋白的SUMO化

六、組蛋白密碼一、組蛋白的乙?；?、組蛋白的乙酰化已知組蛋白乙?；稽c一、組蛋白的乙?；M蛋白乙?；D(zhuǎn)移酶-HATsGcn5/PCAF&p300/CBPBromodomain1.Anacetyl-lysinebindingdomain2.HATs修飾底物之后可能與底物上的乙酰化賴氨酸結(jié)合HATs:MYST(MOZ-Ybf2/Sas3-Sas2-TIP60)HAT識別底物的分子機制NucleicAcidsRes,2004,3:

959-976人類IFN-β基因的激活TheDNAcodecontainsalltheinformationfortheassemblyoftheenhanceosomeinresponsetovirusinfection.DNAcodeinformationprocessing.TheenhanceosomerecruitstheGCN5histone

acetyltransferase.(CandD)GCN5acetylatesinitiallyH4K8andH3K9(C).Anunknownkinaserecruitedbytheenhanceosome

phosphorylatesH3Ser10,aprerequisiteforH3K14acetylationbyGCN5(D).Thehistonecodeisprinted.(E)Translationofthehistonecode.ThebromodomaincontainingtranscriptioncomplexesSWI/SNFandTFIIDarerecruitedtothepromoterviabivalentinteractionsbetweentheenhanceosomeandspecificallyacetylatedhistoneNtermini.Cell.2002Nov1;111(3):381-92.蛋白質(zhì)乙?；{(diào)控基因轉(zhuǎn)錄Transcriptionfactors(TF)canbeacetylated(indicatedbyaflag)byhistone

acetyltransferase(s)(HAT),andthisacetylationincreasesthebindingofTF(suchasp53,seetext)toaDNAsequence.TheactivationdomainofTFcanrecruitaHATcomplextothepromoter.TheHATcomplexthenacetylatestherelevantresiduesofthehistonetailsto‘open’upthechromatin.The‘open’chromatinallowsthebasaltranscriptionmachinery(BTM)tobindandinitiatetranscription.Later,HATs,co-activatorsorotherfactorsintheHATcomplexareacetylatedbyaregulatoryHAT.Afteracetylation,theHATcomplexlosesitsaffinityfortheTFandthusdissociates.Eventually,thedecreaselevelofboundHATcomplex‘closes’thechromatinanddecreasestranscription.Theflagsymbolindicatesacetylation.CurrentOpinioninCellBiology2000,12:326–333組蛋白修飾與DNA損傷修復(fù)Fernandez-CapetilloO,NussenzweigAPNAS2004;101:1427-1428rDNA損傷修復(fù)：A.Homologousrecombination(HR)B.Nonhomologousend-joining(NHEJ)

A.完整的DNA序列；

B.雙鏈斷裂；C.NHEJ因子:(D)修復(fù)因子與(E)染色質(zhì)重塑因子；紅色：磷酸化，藍(lán)色：乙?；?，黃色：去乙酰化；F.染色質(zhì)重塑的構(gòu)型，(G)增大NHEJ局部濃度；

H.直至修復(fù)HDACsr

Histone

deacetylases(HDACs)catalysetheremovalofacetylgroupsfromlysineresiduesinhistoneaminotermini,leadingtochromatincondensationandtranscriptionalrepression.

EighteenHDACshavebeenidentifiedinhumans,andtheyaresubdividedintofourclassesbasedontheirhomologytoyeastHDACs,theirsubcellularlocalizationandtheirenzymaticactivities.NatureReviewsDrugDiscovery

2006,

5,769-784

HDACsr

TheclassIHDACs(1,2,3and8)arehomologoustotheyeastRPD3protein,cangenerallybedetectedinthenucleusandshowubiquitousexpressioninvarioushumancelllinesandtissues.

ClassIIHDACs(4,5,6,7,9and10)sharehomologieswiththeyeastHda1proteinandcanshuttlebetweenthenucleusandthecytoplasm.HDACsrTheclassIIIHDACs(SIRT1,2,3,4,5,6and7)arehomologuesoftheyeastproteinSir2andrequireNAD+fortheiractivitytoregulategeneexpressioninresponsetochangesinthecellularredoxstatus.HDAC11isthesolememberoftheclassIVHDACs.ItsharessequencesimilaritywiththecatalyticcoreregionsofbothclassIandIIenzymes.HDACsrHDACs目的：從我們特有的雜多酸化合物庫(近400種)中篩選得到高活性、特異性的HDI；研究其抗瘤活性及機制。雜多酸的篩選和鑒定：(A).13種能增強報告基因表達(dá)的雜多酸;(B).PAC-320對HDAC活性的抑制作用;(C)PAC-320抑制胞內(nèi)HDAC活性，濃度依賴的上調(diào)胞內(nèi)組蛋白H3乙?；?。PAC-320（μM）15105NaBconAc-H3actinPC3DU145LNCaPAc-H3Ac-H3actinactinABC新型組蛋白去乙?；敢种苿┑暮Y選及其抗癌活性研究雜多酸PAC-320在體外對多種腫瘤細(xì)胞有抑制作用（如結(jié)腸癌SW620、胃癌MGC-803、肺癌A549、乳腺癌MM-231和肝癌HepG2）。雜多酸PAC-320在體外對腫瘤細(xì)胞有較強的抑制作用（肝癌HepG2），而對正常細(xì)胞（肝上皮細(xì)胞L-02）毒性較小。ABCPAC-320抑制體內(nèi)DU145腫瘤的生長：(A)PA-320對腫瘤體積的影響；(B)PA-320對腫瘤重量的影響；（C）PA-320小鼠體重的影響PAC-320對裸鼠體內(nèi)移植腫瘤（DU145）的抑制作用申請的發(fā)明專利：1）組蛋白去乙?；敢种苿┯袡C錫多酸化合物及其制備方法，專利公開號:CN101139368。2）p21WAF1啟動子報告基因組蛋白去乙?；敢种苿┖Y選模型的構(gòu)建及其應(yīng)用，專利公開號：CN101275157。PAC-320濃度依賴的抑制前列腺癌細(xì)胞（LNCaP：AR-positive；DU145：AR-negative）周期停滯在G2/M期(A)，同時上調(diào)p21(B,LNCaP;C,DU145)的表達(dá)水平。PA-320濃度依賴的誘導(dǎo)前列腺癌凋亡：(A)，AnnexinV染色；(B)LNCaP,(C)DU145中活化的caspase3/7表達(dá)水平上調(diào)。(JMedChem,submitted)乙?；腿ヒ阴；D(zhuǎn)錄因子招募HDACs抑制基因表達(dá)

轉(zhuǎn)錄因子招募HATs復(fù)合物激活基因表達(dá)乙?；腿ヒ阴；D(zhuǎn)錄因子招募HDACs抑制基因表達(dá)

轉(zhuǎn)錄因子招募HATs復(fù)合物激活基因表達(dá)二、組蛋白甲基化精氨酸和賴氨酸甲基化過程賴氨酸甲基化賴氨酸甲基化的功能賴氨酸甲基化酶（HKMTs）Yeast,redWorm,yellow

Fly,pinkMammalian,purple

NatureReviewsMolecularCellBiology

2005,

6,838-849

HKMTsNatureReviewsMolecularCellBiology

2005,

6,838-849

ThePRMTs1–8allhaveaconservedAdoMetbindingdomain(shadedingrey)withtheconservedmotifsI,postI,II,andIII,andalessconservedsubstratebindingdomain(lightgrey).PRMTs生物學(xué)功能MAPK激酶在細(xì)胞外信號的刺激下活化MSK1和MSK2激酶，導(dǎo)致H3Ser10磷酸化，活化c-fos和c-jun基因表達(dá)。IKKa激酶活化后導(dǎo)致H3Ser10磷酸化，激活NF-kB表達(dá)。HISTONE-CODEHYPOTHESIS：TheHistoneCodeishypothesizedtobeacodeconsistingofcovalenthistonetailmodifications.TogetherwithothermodificationssuchasDNAmethylationitispartoftheepigeneticcode.Ahypothesisthatproposesthatdistincthistonemodifications,ononeormoretails,functionsequentially,orincombination,todefineacodethatistranslatedbyeffectorproteinswithspecificbiologicalfunctions.

Comprehensiveanalysessuggestthatratherthanconstitutingageneralcode,thecovalentmodificationsofproteins(includinghistones)providesurfacesthatarerecognizedbyeffectorsthatcangiverisetointricateinteractionsanddownstreamevents.Thesearereminiscentofotherregulatoryca