B Y T TRNG I HC DC H NI TRNH HONG CNG H TH TH BT CP VI PROTEIN G V NG DNG TRONG NGHIN CU PHT TRIN THUC MI KHA LUN TT NGHIP DC S H NI 2013 B Y T TRNG I HC DC H NI TRNH HONG CNG H TH TH BT CP VI PROTEIN G V NG DNG TRONG NGHIN CU PHT TRIN THUC MI KHA LUN TT NGHIP DC S Ngi hng dn: 1. PGS.TSKH. L Thnh Phc 2. Ths. L nh Quang Ni thc hin: B mn Ha i cng V c H NI 2013 Page0 LI CM N Trong sut qu trnh hc tp v hon thnh kha lun tt nghip ny, tinhncshngdn,gipqubucaccthyc,ccanh ch, v cc bn. Vi lng knh trng v bit n su sc ti xin c by t li cm n chn thnh ti: Ban gim hiu, Phng o to, B mn Ha i cng V c trng H Dc HNi to mi iukinthunligip titrong qutrnh hc tp v hon thnh kha lun. Ph gio s- Tin s khoa hc L Thnh Phc, ngi thy knh mn ht lng gip , dy bo, ng vin v to mi iu kin thun li cho ti trong sut qu trnh hc tp v hon thnh kha lun tt nghip. ThcsLnhQuang,ngithyngknhtrongcngviccng nh trong cuc sng. Thy ng vin gip v ch bo cho ti rt nhiu ti c th hon thnh c kha lun ny. Xinchn thnh cmn ccthyctrong hingchmkhalun cho ti nhng ng gp qu bu hon chnh kha lun ny. Do thi gian c hn nn kha lun ca em khng th trnh khi nhng thiu st. Em rt mong c c s gp qu bu v s gip ca cc thy c v cc bn sinh vin. Sinh vin Trnh Hong Cng Page1 MC LC LI CM N................................................................................................................... 0 DANH MC CH VIT TT ......................................................................................... 3 DANH MC HNH.......................................................................................................... 6 T VN .................................................................................................................. 8 Phn 1: H th th bt cp vi protein G........................................................................... 9 v cc qu trnh truyn tn hiu trong t bo....................................................................... 9 1.Protein G.................................................................................................................... 9 1.1.S pht hin ra protein G. .................................................................................... 9 1.2.Cu trc ca G-protein. ...................................................................................... 11 1.3. Vai tr ca protein G ...................................................................................... 13 2. H th th bt cp vi protein G ( GPCRs). ............................................................. 14 2.1. Tng quan......................................................................................................... 14 2.2.Phn loi. ........................................................................................................... 18 2.3.Vai tr sinh l. ................................................................................................... 20 2.4. Cu trc GPCR . ............................................................................................... 21 2.5. Tng quan gia cu trc v chc nng. ........................................................... 24 3. M hnh phc h ba thnh phn. .............................................................................. 27 3.1. Cc phi t. ....................................................................................................... 28 3.2. S thay i trng thi ca GPCR....................................................................... 30 3.3. Trnh t cc s kin xy ra khi hormone kch hot tn hiu cAMP:.................... 33 3.4.Sngttnhiu(turnoffofthesignal)vskhuchitnhiu(signal amplification) : ........................................................................................................ 33 3.5 S xo trn ca chu trnh G-Protein ................................................................... 36 Page2 3.6.S iu ha tn hiu G-protein ......................................................................... 38 4.Chi tit 2 con ng truyn tn hiu AMPc v PIP2.................................................. 41 4.1. Con ng truyn tn hiu AMPc...................................................................... 42 L trnh tn hiu ca AMPc........................................................................ 42 S hnh thnh AMPc.................................................................................. 44 Adenylyl cycase ( AC) ............................................................................... 45 Cc cht tc hiu thng qua AMPc............................................................. 46 Protein kinase A (PKA).............................................................................. 47 S phn gii AMPc .................................................................................... 50 4.2.L trnh tn hiu Phosphoinositide.............................................................. 50 DAG.......................................................................................................... 51 IP3.............................................................................................................. 52 Phn 3: nh hng nghin cu thuc mi...................................................................... 53 1. ng dng trong sn xut thuc mi. ........................................................................ 53 2. Trong iu tr ung th..................................................................................................56 3. Trong iu tr bnh tim............................................................................................ 59 4. Trong iu tr bnh do virut ..................................................................................... 60 5. nh hng nghin cu ng dng thuc tc ng vo protein G. ............................. 61 TI LIU THAM KHO Page3 DANH MC CH VIT TT CH VIT TTCH Y GPCRTh th bt cp vi protein G GPCRsH th th bt cp vi protein G ARTh th beta adrenergic mGluRs Th th glutamate Metabotropic SerSerine ThrThreonin -arr-arrestins GEFYu t trao i guanine nucleotide 7TM7-transmembrane receptors SMPhn t tn hiu PKCPhospho kinase C PI3Phosphatidyl inositol triphosphate PLCPhospholipase C ACAdenylate cyclase KLPTKhi lng phn t PKAProtein kinase A GsProtein G kch hotPage4 Giprotein G bt hot NEMN-ethyl-maleimide PTxc t ca vi khun Ho gCTxc t dch t GAPsProtein kch hot GTPase RGSRegulators of G protein signaling EPACsExchange proteins activated by AMPc CGCSCyclic nucleotide gated channels Cross-talkS chng lp UpstreamNgc dng DownstreamXui dng AKAPsA-kinase anchoring protein CREBRespone element binding protein GMPc PDEGMPc phosphodiesterase PLNPhospholamban SERCAsarco/endo-plasmic reticulum Ca2+ - ATPase MC4RsTh th melanocortin 4 ABCATP binding cassette DAG1, 2 diacyl glycerolPage5 IP3Inositol 1, 4, 5 triphosphat CAMCalmodulin Page6 DANH MC HNH Tn hnhS trang Hnh 1: S hot ha protein G bi GPCR ( b kch hot bng cch lin kt vi phi t) 9 Hnh 2: M t cu trc G-protein 11 Hnh 3: Minh ha rt gn qu trnh hot ng ca G-protein 12 Hnh 4: Cu trc ca th th lin kt vi protein G16 Hnh 5 : Phn loi GPCRs19 Hnh 6: Cu trcAR (GPCR)23 Hnh 7: Chi tit cu to chung ca GPCR 2 pha so vi mng t bo 24 Hnh 8: S phosphoryl ha GPCR26 Hnh 9: M hnh phc h ba thnh phn27 Hnh 10:M hnh m t s bin i trng thi cn bng cu dng conformational ca GPCR. 32 Hnh 11:M t s ADP-ribosyl ha35 Hnh 12: Minh ha mt s cu trc 37 Hnh 13: Minh ha mt s vai tr ca RGS protein39 Hnh 14: M phng s khai hot ng thng qua AMPc.42 Hnh 15: AC t 1 n 9 c phn b rng ri 44 44 Page7 Hnh 16: Cu trc domain ca AC 45 Hnh 17: T chc v chc nng ca l trnh tn hiu AMPc 46 Hnh 18: S lc s hot ha PKA48 Hnh 19: m phng s khai hot ng ca 1, 4, 5-triphosphate v DAG 50 Hnh 20: Tc dng ca cc loi protein G58 Hnh 21: Vai tr ca GPCR vi iu ha Ca59 Hnh 22:Cu trc tinh th ca receptor Beta- adrenergic (AR) trng thi hot ng . 82 Page8 T VN Trongcthconngichngchcngnttbotngtcvi nhau. Huhttrong schng c phttrin mnhnccvaitr,chc nng khc nhau. thc hin tt vai tr ca mnh, iu quan trng nht l cc tbolmviccngmtlc, phihphiha vinhau,chngcthcm nhn mi trng v bit nhng g ang xy ra xung quanh chng. Yu t gip cc t bo c th lm c vic ny chnh l cc th th trn b mt t bo. Robert J. Lefkowitz v Brian K. Kobilka c trao gii thng Gii Nobel Ha hc 2012 v gii thch c mt h cc th th lin kt vi Protein G (GPCRs) hot ngnh th no. Trong h th th ny, c ccththpngviadrenalin(cncgilepinephrine),dopamine, serotonin, nh sng, hng v v mi v. Phn ln cc qu trnh sinh l trong c th ph thuc vo hot ng ca GPCRs. Khong mt na cc loi thuc hinnayhotngthngquaccththny,trongcthucchnbeta, thuckhnghistaminvccloithuctmthn.KinthcvGPCRsgip em li li ch ln cho nhn loi. Tuy nhin, cc th th hot ng ra sao, cu tocachngnh thnol1 bn viccnhkhoahcsutmtthi gian di trc khi cc cng trnh ca Robert J. Lefkowitz v Brian K. Kobilka c cng b. Vvy,kinthcvGPCRslhtscquantrnggipchngtavn dngchocccngtrnhnghincusnxutthucmi:ccthuctrbnh tim, Parkinson v chng au na u . Lun vn tt nghip ca ti thc hin vi hai mc tiu sau y: 1.Tng quan kin thc v GPCRs: cu to, vai tr, cch thc hot ng. 2.ng dng trong nghin cu pht trin thuc mi. Page9 Phn 1: H th th bt cp vi protein G v cc qu trnh truyn tn hiu trong t bo Protein G Hnh 1: S hot ha protein G bi GPCR ( b kch hot bng cch lin kt vi phi t) 1.1.S pht hin ra protein G. G- protein c pht hin nh vo th nghim ca Martin Rodbell nm 1971 vs kchhotcAMP biglucagon.Nh thnghimnyMartinRodbell Page10 pht hin ra s hin din ca GTP l rt quan trng trong phn ng ny. ng giyl proteiniu haguaninenucleotide, saunyitnlN-protein, hotngnhbchuynitrunggiangiadiscriminator(receptor)and amplifier (effector; i.e., adenylate cyclase). Sau , ng thy rng adenylatecyclase c kch hot mnh m v khng thongcbimtanalogGTP,5'-guanylylimidophosphate,hoc[GPP (NH)-p]. V GPP (NH)-p c kh nng chng thy phn nn Rodbell cho rng GTPl"chtthyphntivngtchot",cnghal,bchuyniging nh GTPase. iu ny sau c th hin r hn bi Cassell v Selinger vonm1976.ScmtcaproteinbmGTPringl,khcbitvicc enzymeadenylatecyclase, c xc nh biAlfredGilmanvngnghip ngitithitliGPP(NH)-p-,1chtkchthchhotngadenylate cyclase trong mng t dng t bin t bo ung th hch (cyc-) - c adenylate cyclasenhngthiuG-proteinbngcchbsungthmyut40kDaGTP bm ring bit. Nm1980,HowlettvGilmanchorngskchhotludicaG-protein kch hot cyclase lm gim lng phn t protein, nhn mnh rng G-protein c to thnh bi nhng tiu n v c th li gii c. Cu trc tam th (3 thnh phn) ca G-protein c pht hin bi Stryer v cng s. H chng t c rng s kch hot Gt bi Gpp(NH)-p v nh sng dn n s phn ly caphchptrimeric,tonnGpp(NH)-pbmtv(tcvaitr kchhotskhphosphorylha).Nm1985,-transducinctothnh bi 4 nhm vi cc trng nhm l Numa, Boume, Khorana, v Simon; Nm 1986, cu trc ca tiu n v c xc nh y bi nhm ca Gilman. Rodbell v Gilman c trao gii Nobel vo nm 1994. [1] Page11 1.2.Cu trc ca G-protein. G-protein cgm 3thnh phn:tiunvc KLPT~3945kDa,tiu n v c KLPT ~37 kDa v tiu n v c KLPT ~8 kDa . C khong 20 gen m ha nhiu loi tiu n v , 6 gen i vi tiu n v v 12 gen cho tiu n v . trng thi trimer ha, G-protein bm vo mt trong ca mng t bo thng qua ui k nc ca tiu n v v (myristoyl v palmitoyl trn,farnesylhocgeranylgeranyltrn).Tiunvvcnili vi nhau bi lin kt gi li vi li to nn -dimer; tiu n v ca -dimernysbmvotiunvbngtheokiubsungvnglinkt peptidetrn2proteinvstngtcviuiknc.KhiG-protein c kch hot, lin kt gia tiu n v v b t, trimer b phn ly thnh tiu nvmonomericvtiunvdimeri.Tiunvvu bm vo mng t bo nhng cng d dng tch khi mng khi cn.[59] Hnh 2: M t cu trc G-protein Page12 Tiu n v c 2 vng chc nng quan trng khc ngoi vng ni kt vi tiu n v . Mt l, tiu n v tc ng vi th th v tr 5 amino acid cuicauCtn.Hailnmangvnggnktviguaninenucleotide thchinchcnng GTPaseca G-protein.Mckhc, c 2tiun vv u c th tc ng n b mt tc ng ca G-protein. Tiu n v v c lin kt cng ha tr vi neo lipid , do vy bm dnh v c nh G-protein vo mt trong mng t bo. Sau khi tch ra khi protein G, tiu n v s hot ha enzym Adenylate cyclase (AC) Adenylate cyclase (AC) l mt protein xuyn mng, vng hng v pha bo tng c gi l vng thy phn (catalytic site). Enzym AC s gip chuyn ATP thnh AMPc Hnh 3: Minh ha rt gn qu trnh hot ng ca G-protein. Page13 1.3. Vai tr ca protein G [1] [2] Protein G trong 1 s qu trnh sinh l. Sau ny, ngi ta tm ra nhiu loi protein khc nhau, mi loi c hot ha bi1receptorringvnkchhoththngkhuchiring.Dnn nhngthayikhcnhautrongtbo.Vdnhtrongvngmcmt, proteinGchuynitnhiunhsngkchhotlnnhngsidythn kinhmtruyntkchthchthgiclnno.Nhnbitvmicngph thucvoproteinGtrongcctboolfactory(tbokhugic).Vcm gic hng v cn lin quan n nhng protein G khc . Mt s protein G kch thch hoc c ch s hnh thnh caAMPc, v th c schuynhatrongtbo.ProteinGlmthayilulngccionqua mng t bo v thay i hot ng t bo. Protein G cn nh hng n qu trnh phosphor ha protein do kim sot qu trnh phn chia v nhng qu trnh khc ca t bo. Protein G v bnh l. Nhiu triuchngcabnh cgiithch ldosthayichcnngca ProteinG.Vdbnht,mtbnhtruynnhimnglonginhtca ngtiuha.Bnhldovikhunsnxut1 ctrtc.Ccct ngvaitrnh1loienzymlmthayi1trong nhng proteinGlun trng thi hot ng. iu ny ngn cn s hp thu nc v mui rut mt cch bnh thng. Kt qu s mt nc v mui c th dn n t vong. Nhim khun E.coli cng c triu chng tng t. Trong trng hp b nhim khun ho g th c t li ngn cn s hot ng ca protein G. Do hng ro min dch b tn thng. Page14 Trong mt s bnh ph bin, s lng protein G trong t bo thay i. C th c qu nhiu hoc qu t . Nh trong bnh tiu ng v nghin ru c mt s triu chng l do thay i tn hiu ca protein G. Ngi ta thy rng biu hin suy gim protein G c th lm nh hng ti s phttrinvrilonchuynha.nhngngitbinvhottnhqu mc ca protein G c th l nguyn nhn ca mt s khi u. Tng hot ng ca protein G cn c tm thy trong ri lon ni tit di truyn nhng him gp nh hi chng Mc-cune Albright ( da c cc m mu c ph sa v bin dng xng) . Trong trng hp ny, mt s t bin ca protein G dn n chuyn ha calci b gin on , dn n bin dng xng. Gn yngitakhm phracc protein Gnhchc mt n v.Chng ccutrcgngingccsnphmcatinoncogenlnhngproteinchc nng ca t bo nh: tham gia vo cc qu trnh sinh trng , pht trin, tnh trng b xng t bo, vn chuyn bn trong t bo, hot ng thc bo, bi tit,VdnhccproteinGnhthuchraskimsotsphttrint bo, iu ha qu trnh oxy ha thc bo trong bch cu. S t bin protein Gkhinchngcthtrthnhsiuhotngvdocvaitrchcnng trongqutrnhsinhtrngcatbonhtrndockhnnggyung th. H th th bt cp vi protein G ( GPCRs). 2.1. Tng quan. Ti sao cn c th th GPCR trn mng t bo ? Mi t bo ngi u c bao bc bi mt lp mng t bo. l mt lp phospholipidkp.Lpmngnychophptboduytrmthnhpnht nhccchtcvaitrhasinh,ngthingnngacchachtkhng Page15 mong mun bn ngoi mi trng c th xm nhp t bo. c th thc hin y chc nng ca mnh, cc b my sinh ha bn trong t bo cn 1 c ch cho php n c th nhn c cc thng ip v mi trng bn ngoi t bo. Cc thay i v lng hormone bn ngoi t bo c th iu khin nhng hot ng ca enzyme ni bo. Cc phn t c mi thm tc ng vo cc t bo thuclpbiumkhu gic.Ngoiraccchtctrongthcn cthnh hng n hot ng ha sinh din ra bn trong t bo chi v gic sau lan truyn di dng cc tn hiu in t n no b. Thct,cctbongiuthngxuyngiaotipvinhauvvimi trng xung quanh. lm c iu ny, t bo cn 1 h thng cc phn t v 1 c ch truyn thng tin hiu qu i qua mng t bo. Ngoi ra, trong c th qu trnh truyn tn hiu c th phi din ra vi 1 khong cch kh xa. Do , c th phn ng ng lc, no b cn nhn thng tin rtnhanh t cc gicquan, nhthgic,khugic,vgic.v.v.Thm mtlnna, iuny cngcnmtcchtruynthngtiniquamngt bo. GPCRsnggp vai tr quan trng trong h thng truyn thng tin t bo. Cc vn chnh ca GPCR Cc GPCR truyn n t bo mt lung thng tin cp n cc iu kin bnngoi.Cch mc phnt ca qutrnhnydinranh thno? C nhng phn t no tham gia v bng cch no chng truyn c tn hiu? Lm th no chng phn bit c cc loi tn hiu khc nhau? Bng cch no cc tn hiu c iu khin? l nhng cu hi quan trng trong lnh vc ny cc thp nin trc. c th tr li, cc nh khoa hc phi xc nh nhng thnh phn phn t tham gia qu trnh truyn tin v theo di cc Page16 hot ng ca cc phn t ny thng qua cc nghin cu ha sinh, sinh l v cu trc. Th th lin kt G protein . ThthlinktGprotein(GPCRs)ngvaitrquantrngtronghthng truyn tin t bo. l cc protein nm trn mng t bo. Tn gi th th lin kt G protein l ni n c ch truyn tn hiu ph bin nht thng qua th thlccproteincthlinktviGTPbntrongtbo.Bivcc chuipeptidecaGPCRthnggpkhc7lnquamngtbonntrong nhiutrnghpGPCRcngcgilthth7vngxuynmng(7-transmembrane receptors, 7TM). ( hnh 4) Hnh 4: Cu trc ca th th lin kt vi protein G Tn hiu (signal) truyn t th th trn (7-helix receptor) n mt protein ni bocgilG-protein,dovynhmththnycncgilG-Page17 Protein-CoupledReceptors(GPCR).Ckhong800GPCRctmthy ngi. [59] GPCR c nh hp (dimerize) hoc oligomer ha to thnh mt phc hp ni mng. Ligand bm vo th th s truyn tin i vo cu trc ny v sinh ra cc tc ng tng ng c trng cho tng loi th th.CnhiuloiGPCR-interactingproteins(GIPs)iuhachcnngcath th. Nhng tc ng ny bao gm:- Thay i i lc ca ligand.- iu ha s nh hp hay oligomer ha ca th th.- nh v v tr ca th th, bao gm c vic vn chuyn hay loi b chng t mng t bo.- Kim sot s tng giao ca cc protein thng tin khc.ThthbtcpproteinGchctmthytrongcc sinhvtnhnchun, baogmc nmmen, trnguiroidngphu (choanoflagella),[23] v ngvt.Cc phith bmvovkchhotththGbaogmcchp chtnhycmvinhsng,phntmihng, pheromone, kchhmt, v chtdntruynthnkinh;ccphithnyrtadngvkchthct nhng phn t nh cho n cc on peptide hay cc protein ln. Th th bt cp protein G c lin quan ti nhiu bnh tt trong c th v cng l mc tiu ca khong 30 phn trm s dc phm hin nay. [24] [25] C hai qu trnh dn truyn tn hiu ch yu c s gp mt ca th th GCPR: qu trnh AMP vng v qu trnh phosphatidylinositol. [26] Khi mt phi th bm vo GPCR, n khin cu hnh ca GPCR thay i v iu ny cho php GPCRhotngnhmt nhnttraoiguaninenucleotide (guanine nucleotideexchangefactor-GEF).TclGPCRshothamt protein Page18 G i km vi n bng vic trao i GDP ca n cho mt GTP. Tiu n v ca protein cng vi GTP lc ny c th tch ri khi cc tiu n v v tc ng n cc protein dn truyn tn hiu ni bo hay cc protein chc nngch;cinytythucvotiunvthucvoloig (Gs, Gi/o, Gq/11, G12/13). [27] 2.2.Phn loi. S lng chnh xc ca i gia nh GPCR hin nay vn cha bit ht nhng c gn 800 gen ngi khc nhau (tng ng vi 4% ca ton b b gen m ha protein) c pht hin ra t phntch trnht b gen l m ha cho ccGPCR.[28]Cnhiuhthngphnloicxutvhthng phn loi c bn chia i gia nh GPCR thnh ba nhm chnh (A, B, v C) v 1nhmkhngthphthincstngngvtrnhtacidamingia ccGPCR. LpchimslnglnnhtchonnaylloiA,chimgn 85%ccgenGPCR.TronglpAthhnmtnatrongsnymhath thkhugictrongkhiccththcnliskthpvicchpchtni sinh c bit n hoc l khng lin kt vi phi t no. Tuy khng c s tngngvtrnhtspxpacidamingiacclp,nhngttccc GPCRsucchungmtcutrcvcchtruyntnhiu. Ttccc GPCRsc th cchiathnh6lphc datrntrnhttng ng acid amin v c chc nng tng t nhau: [29] [30] [31] [32] Lp A (hoc 1) ( ging Rhodopsin)Lp B (hoc 2) ( h th th secretin)Lp C (hoc 3) (glutamate Metabotropic / pheromone)Lp D (hoc 4) (th th pheromone sinh sn nm)Page19 Lp E (hoc 5) (th th AMP vng )Lp F (hoc 6) (Frizzled, Smoothened)LpA:ththgingRhodopsinl mtlpcslngthth rtln.Lp ny c chia nh hn na thnh 19 nhm (A1-A19). [33] Gny,cmththngphnloikhccgilGRAFS(glutamate, Rhodopsin,Adhesion,Frizzled/Taste2,secretin)cxut.[28] H gen ca con ngi m ha hng ngn cc th th protein-coupled G, [32] khong 350 trong s pht hin hormone, yu t tng trng, v phi t ni sinhkhc. Khong150caGPCRstmthytronghgencaconngic chc nng khng r. Mt s t chc v thng tin sinh hc , cc nh pht trin thuc phn loi cc GPCRs theo trnh t cc acid amin ring l ca GPCRs. y h s dng phng php dng cc acid amin khng t nhin. [33] [34] [35] Hnh 5 : Phn loi GPCRs Page20 LpA ( ging Rhodopsin),lp B ( ging secretin), lp C (ging th th ca glutamate),khc ( Adhesion (33), Frizzled (11), taste type 2 (25), cha c phn lp (23)) .2.3.Vai tr sinh l. Cc th th lin kt vi protein G tip nhn nhiu loi tn hiu sinhl bn ngoi t bo. Cc tn hiu c th ls thay i nng peptide, hormone, lipid, cht dn truyn thn kinh, ion, cht c mi, cht c v hoc l cc chm photons n mt. GPCR sau chuyn ha cc tn hiu ny vo bn trong t bo v kch hot mt chui cc phn ng tng ng c s tham gia ca nhiu protein, nucleotide hay ion kim loi, v cui cng dn n mt thng ip hay mt phn ng sinh l t bo thch ng. Crtnhiuccqutrnhsinhltbongvtcvcnccthth 7TM. ng thi chnh nhng th th ny cng l ch ca mt lng ln cc ha cht dc phm. Trong b gene ca ngi c khong 1000 gene m ha cc loi th th 7TM khc nhau v chng lin quan n qu trnh cm ng vi hnglotcckchthchntmitrngngoibo.Vdccthth adrenaline,ththdopamine,ththhistamine,ththnhsngrhodopsin v rt nhiu th th lin quan n khu gic v v gic. Mt s v d v vai tr sinh l ca GPCR bao gm: Vaitrtrongthgic:ccopsinssdngmtphnng photoisomerization chuyn bc x nh sng thnh tn hiu in dn truyntbod.Vd:Rhodopsinsdngvicchuyni11-cis-retinalthnhdngtranschuynnhsngthnhtnhiuin. [1trang 439-447] Page21 Khu gic: cc th th ca biu m khu gic (th th khu gic) lin ktviccphntmivpheromone(kchthcht)(thth vomeronasal) Linquanticmxc,tmtrng:ccththmngtbonolin ktviccchtdntruynthnkinhkhcnhau,baogmserotonin, dopamine, GABA, v glutamate. Thamgiavohotngmindchvphnngvim:ccthth chemokine lin kt phi t l cc cht dn truyn trung gian gia cc t bo ca h thng min dch, cc th thnhth thhistamin lin kt vi phi tgy vim.Tham gia vo h thng dn truyn thn kinh ch ng : c hai h thng thnkinhgiaocmvphgiaocmcquynhbiccGPCR, chutrchnhimkimsotnhiuchcnngtngcacthnh huyt p, nhp tim, v qu trnh tiu ha. Cm ng mt t bo: Mt vai tr mi pht hin ca GPCR l trong vic iu chnh cm ng mt t bo. iu chnh cn bng ni mi (v d, cn bng nc). [38] Tham gia vo s pht trin v di cn ca mt s loi ung th. [39] 2.4. Cu trc GPCR . GPCRs l cc protein c lp mng t bo m c by vc xuyn mng hnh dngtridihocdngvngxon.Ccphnngoibocaththcth cglycosylated.Ccvng ngoibocha haicysteine hnhthnhlin ktdisulfidennhcutrcthth.Mts proteinGPCRsxonby Page22 mng tng t (channelrhodopsin) c th cha cc knh ion trong protein ca chng C cu trc tng t nh GPCRs, cc th th adiponectin 1 v 2 (ADIPOR1 vADIPOR2)cngc7vcxuynmng.TuynhinADIPOR1v ADIPOR2 l c hng tri chiu vi GPCRs trong mng t bo (v d, th thcuiNH2 trongtbocht,vphnngoibothutncngl nhm carboxyl) v cc th th ny khng lin kt vi protein G. [40] MhnhcutrcutincaGPCRsngidatrnstngngvi rhodopsin ca vi khun ( s tng ng ny l rt t) , cu trc rhodopsin ca vikhuncxcnhbiphngphpnhiuxint(PDB2BRD, 1AT9) [41] [42]v X quang da trn tinh th (1AP9). [43] Nm 2000, cu trc tinh th u tin ca mt GPCR ng vt c v, l b Rhodopsin (1F88), c tm ra [44] .Trong khi cc tnh nng chnh v cu trc 7 vc xon tng ng thhng ca 7 vng xon khc bit rt ln vi rhodopsin ca vi khun.Trong nm 2007,cu trcu tin ca mt GPCR ca con ngi c tm ra(2R4R, 2R4S). [45]. Ngay sau l pht hin ra cu trc c phn gii caohncareceptor(2RH1)gingvi2receptor(2R4R,2R4S)vami phthincutrctrc[46][47].Cutrcthth2-adrenergicrt gingviRhodopsinbvnhhngtngicaccvngxonby mng.Tuynhin,cutocavngthhaingoibolhontonkhc nhau gia hai cu trc. T v tr vng ny th vng ngoi bo cu to ln mt cinp che phvtrlinktcaGPCRviphit.Skhc bittrong cutrcnylmnibtlnnhngkh khntrongvicxydngmhnh cu trc tng ng ca GPCRs khc ch da trn cu trc Rhodopsin . Page23 Cc cu trc ca GPCR lc bnh thng v lc lin kt vi cht ch GPCRs cng c xc nh. [48] [49] [50] [41] .Nhng cu trc ny cho thy cc phi t lin kt phangoi bo ca mt th ths dn n nhng thay i cu trc phn nm pha t bo cht ca cc th th. S thay i ln nht khi c phi tlinktl2xon 5v 6(TM5vTM6).Ccukchhot qu trnh sinh l m c th l hot ha protein G cath thbeta-2 adrenergic trng thi Gs ( lc ang c phi t lin kt) khng nh G lin kt vi mt khoang c to ra bi s thay i cu trc ca 2 xon 5 v 6. [52] Hnh 6: Cu trcAR (GPCR) th khng hot ng bn tri,cu trc AR dng hot ng khi linkt phitv protein G bnphi. Khic phi tlinktthcutrc cathththayinmragingnh mt bhoa. hnhphadicc Page24 nguyntnhnhng qu bngnh. Phnthn nccmu xanhsng,cn phn k nc c mu xanh m hn. Khi c hormone lin kt vi GPCR th phn k nc s m ra to thnh khong trng cho tiu n v ca protein G gn vo. 2.5. Tng quan gia cu trc v chc nng. Hnh 7: Chi tit cu to chung ca GPCR 2 pha so vi mng t bo Vcutrc,GPCRsccimlcmtuNH2phatncng ngoi t bo, tip theo l by vc xuyn mng (7-TM)cc chui xon kiu (TM-1 ti TM-7) c kt ni bi ba vng pha bn trong t bo (IL-1 IL-3)vbavngngoibo(EL-1tiEL-3),vutncngtrongnibol nhm COOH .Page25 Cc GPCR sp xp cc phn ca n sao cho to cu trc ging nh mt chic thng, vi by vc xuyn mng to thnh mt khoang bn trong mng t bo phi t c th lin kt trong khoang ny v khoang thng c bao ph biEL-2.Thayvtngtcviccvngngoitbo,phitcngcth kt hp nhng ni khc, v d nh trng hp ca cc phi t cng knh hn(vd,proteinhocpeptideln),linktviththglutamate Metabotropic ca lp C (mGluRs) v trl ui NH2 .Cc GPCRs lp C c phnbitviccGPCRs khcbiutncngNH2 rng ,iu ny gip cho cc phi t c th lin kt ti v tr ny. Khiglutamatelinktvimt mGluR, utncng NH2phitri qua mt s thay i cu trc dn n s tng tc ca n s lm thay i cu trc vng ngoi bo ( EL 1, EL2, EL3)v cc vc TM. Hiu qu cui cng ca ba loi hot cht ch vn( cht ch vn, cht ch vn ngc, cht i khng)gy ra mtsthayitrongnhhngtngicaccxonTM(vnhmt chuyn ng xon) dn n khoang th th trong mng t bo rng ln hn vchnhsthay ivhnh dng xoncacc vcTMvccvng ( EL1, EL2, EL3, IL1, IL2,IL3) s bo hiu chc nng dn truyn thng tin (v d, to khp ni vi G-protein, qua kch hot protein G, v qu trnh truyn tin btu xyra).Chtchvnngcvchtikhngcngcthlinkt vimtsaimkhcnhaucaGPCR,nhnghiuqucuicngcng phi c ngn nga TM xon theo nh hng ny. Cu trc c nhm NH2 v COOH tn cng ca GPCRs cng c th phc v ccchcnngquantrngngoiviclinktviphit.cbit,u-COOHtncngthngchaserine(Ser)hocthreonin(Thr),khichngb phosphoryl ha, s gytng cng i lc trn b mt th th bn trong t bo to iukin choskt hpvicc proteinkhccgil -arrestins(-Page26 arr).[33]Mtkhilinkt,-arrestinssthayicutrckhnggiangy ngnchnkhpniviG-proteinvcthtuynchnccproteinkhc. Phn ng phosphoryl ha cc Ser v Thr thng xy ra nh mt kt qu ca vic GPCR b kch hot, -arr vi vic lm cho GPCR tch ra khi protein G vlm bt hot GPCRl c ch quan trng ca s gii mn cm. [53] Hnh 8: S phosphoryl ha GPCRS phosphoryl ha GPCR dn ti th th kt hp vi -arrestinsv b nhp vo bo tng qua kch khot ERK 1,2 ( cc kinase) gy gii mn cm. GPCRs p ng vi cc tn hiu ngoi bo qua cc cht truyn tin trung gian ( phit).Ccphitrtangcthlprotein,ccaminsinhhcv proton. Nhng tt cqu trnh truyn tnhiu t cc phi t ny phi thng Page27 qua mt c chl G-proteinlinktkhpvo GPCR. iunycthc thchinnhmtyuttraoiguaninenucleotide(GEF).Mingnvi protein G ch yu c hnh thnh bi s kt hp ca IL-2 v IL-3 cng vi tn hin xon cc vc TM khi GPCR lin kt vi phi t. M hnh phc h ba thnh phn. Ba thnh phn l (17) 1.phi t ngoi bo,2.S thay i trng thi ca GPCR3.G protein ng vai tr hot ha tn hiu Cc phi t (c th l hormone, cht truyn xung thn kinh, hp cht c mi .v.v)bm ln phnngoi bocaththtrongkhi G-proteinlinktvi phn ni bo ca th th. Hnh 9: M hnh phc h ba thnh phn Page28 Bn tri: m hnh phc h ba thnh phn [19]. Mt chu k nhit ng lc hc phctpmtshnhthnhlinktcaccphit(muvng),thth (mu xanh) v G-protein (mu ).Bnphi:Cutrctinhthphch3thnhphntrngthilinktvi nhau. M hnh cc vng xon ging nh di duy bng c to ln bng cch cn c vo cc ta cc phn t t tp tin 3sn6.pdb [21]bng cch s dng phn mm Molmol [22]. G th th protein-coupled c kch hot bi mt tn hiu t bn ngoi (mt phi t ) . iu ny to ra mt s thay i cu trong cc th th, lm kch hot mt loi protein G. Hiu qu sau khi phi t kch hot GPCR ph thuc vo loi protein G m GPCR gn kt. 3.1. Cc phi t. Phn t tn hiu ( phi t) l nhng phn t ha hc c tit ra t mt t bo ckhnngkhingmt chui phnngsinhhcnibo quatrung gian th th. Do vy c th xem n nh mt phng tin lin lc ca t bo, c gi l SM (signaling molecule). Cc SM c to ra t bo kim sot hot ngcachnhn(autocrine)hoclncn(paracrine)hayphngthchvo mu n kim sot hot ng ca t bo khc (endocrine). S khc bit c bngiacchnhthcnylthigian,paracrinevautocrinechopng tc th, cn endocrine cho p ng sinh hc chm hn nhiu.C th xem y nh mt ligand. C 2 c tnh c bn sau: [59] -Ccligandcthgnktvinhiuloiththkhcnhau sinh ra cc p ng thuc cc loi khc nhau. V d: SM nh NE c th gn vi th th 1 thc hin phng thc cn tit hoc 2 thc hin phng thc t tit.Page29 - Nhiu ligand c th gn kt vi cng mt loi th th sinh ra ccpnggingnhau.Vdligandgnvothth1,ET (th th endothelin) v AT1 (th th ca angiotensin II) u hot haPLC(PhospholipaseC)quaproteinGqribiniPIP (phosphatidylinositolbiphosphatethnhphosphatidylinositol triphosphate (PI3) mt mt gii phng Ca2+ li ni bo, mc khchothaPKC(phosphokinaseC)phosphorylhaknh calcium loi L lm m knh ny. Ngoi racn mthnh thckhc trongphnloi vstngquangiacc phn t tn hiu v c quan ch c lm r qua v d sau. d dy, gastrin c phngthchvomuhotha tbo ECL(enterochromaphil-likecell) titrahistamine,sauhistaminekchthchbmprotonthnhtbo phngthchionH+,nhthslinlcgiatboGvitboECLl endocrine trong khi ECL vi t bo thnh l paracrine. GPCRs gm c cc th thvi phi t trung gian l cc tn hiu gic quan (v d,ccphntkchthchnhsngvkhugic),adenosine,bombesin, bradykinin,endothelin,axit-aminobutyric(GABA),yuttngtrngt bogan(HGF),melanocortins,neuropeptideY,peptideopioid,opsins, somatostatin,GH,tachykinins,ccthnhvincagianhpeptiderutnon ctcdngvnmch,vvasopressin,ccaminsinhha(vd,dopamine, epinephrine,norepinephrine,histamine,glutamate(tcdngmetabotropic), glucagon, acetylcholine (tc dng muscarinic), v serotonin); chemokine; cc lipidtrunggiancaqutrnhvim(vd, prostaglandin, prostanoids,yut kch hot tiu cu, v leukotrienes) v hormon peptide (v d, calcitonin, C5a anaphylatoxin, hormone kch thch nang trng (FSH), gonadotropin-releasing Page30 hormone(GnRH),neurokinin,thyrotropin-releasinghormone(TRH), cannabinoids , v oxytocin).NgoiracncGPCRsmbkchhotngbitcnhnkchthchcha c xc nh c gi l th th m ci. Trong khi , trong cc loi ca cc th th c nghin cu, phi t lin kt vi GPCRs t bn ngoi mng t bo .Cc phi t ca GPCRs thng lin kt trong vi cc vc xuyn mng (TM). Tuy nhin, cc th th kch hot bi proteasethckchhotbisphntchmtphncaminngoi bo ca GPCR( EL1, EL2, EL3) [54]. 3.2. S thay i trng thi ca GPCR. Vic dn truyn cc tn hiu thng qua cc mng t bo bi cc th th trc khigiiNobel Ha hc 2012cng b thvn chahontonhiur.2nh khoahcnhngiiNobel2012giithchccchtruyntinca GPCRlsthayicutrcdlpth.KhiccGPCRtrngthihot ngthchngslinktviccproteinGkhnghotng.Mtkhicc phi t lin kt vi th th , GPCR s thay i hnh dng, do kch hot cc protein G, protein G sau khi b kch hot s tch ra t cc th th. Cc th th thbygicthhockchhotmtproteinGkhchocchuyntrli trng thi ban u ca n. Mtphntththtntitrongmttrngthicnbngcudng( conformational) giacctrngthisinhhchot ngv khnghot ng [55]Linkt ca ccphitvi ccththcththay iscn bng i vi cc trng thi ny [56].Ba loi phi t tn ti:cht ch vn l phi t m lm thay i s cn bng ca th th sang trng thi hot ng, cht ch vn nghcholphitmthayiscnbngcaththsangtrngthi Page31 khng hot ng v cht i khng trung tnh l phi t m khng nh hng n trng thi cn bng. C ch conformational-coupling (s gn kt c bin i cu dng) Thng tin c th c chuyn t mt nguyn t tn hiu n mt nguynttnhiutip theonhvoqutrnhconformational coupling.Nunhngthnhphnthnglproteinnylin kt vi thnh phn khc thc ch truyn tin s xy ra rt nhanh. Mt v d kinh in cho c ch conformational coupling l s co gin c bm xng ni m knh Ca tup L sn sng ni kt viththryanodine(RYR1).Mtvdkhclskthp giaknhCa 2+phthucinthviproteinpngvi hin tng xut bo cc ti synaptic. Sconformationalcouplingcngcdngkhithngtin cchuynibiskhuychtncaccnguynttnhiu. Nhng phn t truyn tin th hai c khi lng phn t thp (Ca 2+ ,AMPc,GMPc,vRos)hocccproteinnhERKhay nhiuyutphinmchothakhcdichuynttbo cht vo nhn mang theo thng tin trong sut qu trnh di chuyn trongtbochtcachng.Trong qu trnhchuyngiaothng tin ny, nhng nguyn t c kh nng khuch tn ny s dng c chconformationalcouplingtruynthngtinkhingn vo cac yu th thun dng khc. Page32 Hnh 10:M hnh m t s bin i trng thi cn bng cu dng conformational ca GPCR. Phi t lin kt vi thth gyra kt qu l GPCR t chc li hnh dng cho php kch hot cc protein G-alpha. Hnh bn tril theo hng t pha trn v pha bn ca GPCR nh n c thit lp trong mng t bo (cc cht bo mng c b qua cho r rng).Hnh bn phi ltheo hng nhn ln mng t bo t bn trong t bo. [58] Page33 3.3. Trnh t cc s kin xy ra khi hormone kch hot tn hiu cAMP:- Lc u, tiu n v ca G-protein ni kt vi GDP v ba tiu n v , v thng nht vi nhau v 2 tiu n v v c ch G.- Khi hormone bm dnh vo th th GPCR, s c mt s bin i lp th xy ra vthngtinstruyntiG-protein.Vngktninucleotide(nucleotide-binding site) tiu n v tr nn nhy cm hn vi bo tng v v nng GTPca botngtaohnhnGDP nnngiiphng GDP nikt vi GTP. Qu trnh ny gi l GDP-GTP exchange.-SthayidinratrndnnsbinicutrccaGvnri phc hp lin kt vi Adenylate cyclase.-AdenylatecyclasechothabiG-GTPsauthchinphnng tng hp thy phn to ra cAMP.-ProteinkinaseA(cAMP-Dependentproteinkinase)thyphnvchuyn nhm phosphate ca ATP n nhm serine hoc nhm threonine ca mt vi protein ni bo v kch hot hot ng ca chng. 3.4. S ngt tn hiu (turn off of the signal) v s khuch i tn hiu (signal amplification) : S ngt tn hiu. - G thy phn GTP thnh GDP v Pi (GTPase). S tn ti ca GDP trn G khinntiniktvitiuphnvbthotdovyadenylatecyclase khng cn hot ng na.- Phosphodiesterase thy phn cAMP thnh AMP.- Th th t lit (receptor desensitization) bin i cu trc khc vi cu hnh cahormone.Trongmtstrnghp,receptorhothacphosphoryl ha thng qua G-protein receptor kinase. Th th c phosphoryl ha s ni Page34 ktvi-arrestin.Sau,-arrestniuhnhqutrnhloibreceptort mngtbovobotng bihintngnhpbonhtcnggintip ca clathrin (clathrin-mediated). -arrestin cng ni kt vi phosphodiesterase ni bo, mang enzyme ny n gn ni sn xut cAMP, gp phn lm ngng dng phn t tn hiu.-Proteinphosphatasethyphnloinhmphosphatecan.(trcn c phosphate ha bi protein kinase A). S khuch i tn hiu L mt cng on rt quan trng trong dng thc tn hiu. C th:-Mt phnthormone cth dn n qutrnh tothnhnhiuphn t cAMP.- Mi tiu n v xc tc ca protein kinase A xc tc phosphoryl ha nhiu protein trong sut qu trnh tn ti ca cAMP. CcthngphnkhccaG(differentisoformsofG)cnhngcch truyntinkhcnhau.VdnhstimulatoryGsgnviGTPthhotha adenylatecyclasenhngkhiinhibitoryGignviGTPthnlibthot enzyme ny. Do vy c th thy Gi c vai tr quan trng trong vic chuyn ngc li GDP thnh GTP v sau li hot ha Gs. Page35 Hnh 11:M t s ADP-ribosyl ha. Phc hp G c gii phng khi G ni kt vi GTP dn n vic hot ha haycchmtviloiproteinkhc.Vd,Gcchmtvithng phn ca adenylate cyclase (isoform) gp phn ngt dng tn hiu vo t bo, ngng biu hin enzyme.ctt(choleratoxin)xctcnghatrsbinthcaGs.ADP-ribose c chuyn t NAD+ thnh arginine ti vng hot ng ca GTPase Page36 caGs.SADP-ribosylhangnsthyphncaGTP(preventsGTP hydrolysis) bi Gs. Do vy stimulatory G-protein c hot ha lu di.Pertussis toxin (whooping cough disease) xc tc s ADP-ribosyl ti cysteine ca Gi lm n khng th chuyn GDP thnh GTP. Con ng inhibitory b kha (The inhibitory pathway is blocked).SADP-ribosyllcchchungiuhahotngcaprotein,tsinh vt nhn s (prokaryotes) n sinh vt nhn thc (eukaryotes), k c ng vt c v. 3.5 S xo trn ca chu trnh G-Protein [59] Chu trnh ca G-protein c th b xo trn bi nhng con ng sau: 1.Socachutrnhdavosthyphnca-phosphateca GTP.iunyxyrakhimtdnxutcaGTPniktvothth nhngkhngckhnngthyphnhaythyphnchmniktvi tiunv.Vd,5-guanylylimidophosphate(Gpp(NH)-p)hay guanosine5-O-(3-thiotriphosphate)(GTPS),haythmvoAlF4,to cc triphosphate gi (pseudo phosphate) trn GDP trong G- GDP.Trongnhngiukinny,shothaccchttchiutr thnh khng thun nghch. Th th c kch hot s xc tc chu trnh G-protein,vbnchtcnggingnhkhicligandktninhng chmhnt100n1000ln.Khithiuskchhotththbi ligand, chu trnh c bn chm s xy ra. Nguyn nhn c th l v phn nh ca th th hin din trong th hot ng ngay c khi thiu ligand. Kt qu l, s thay i Gpp(NH)-p hay GTPS bi GTP hay s c mt caAlF4ngvaitrtoraccpngtchiu(effectorresponse) Page37 trong khi thiu ligand th th. Tuy vy, s kch hot vn chm hn khi c s hin din ca ligand. Hnh 12: Minh ha mt s cu trc [59] 2.ChutrnhcthchmlikhithmvonhngGDPdthahay, guanosine5-O-(2-thiodiphosphate)(GDPS)mtdnxutnnh hn. Khng ging GTPS, GDPS c lin kt thun nghch nn n ch cnh tranh vi GTP. Do vy n s ch hot ng nng cao hn tiu chun t 10 ln tr ln. 3.Khi c s hin din ca NAD+, tiu n v ca G-protein c th b ADP-ribosylatedbi2loiProteinvikhun.ctcavikhunHo g(whooping-cough)(PTx)ADP-ribosylatescysteineuCtnca G-proteincanhmGivGongncnsbtgpcaG-proteinth Page38 th v nng chn s hot ha GPCR. . N-ethyl-maleimide (NEM) cng alkylhacysteinstheocngcch.ctdcht(CTx)ADP-ribosylatesargininetrongG-proteinscalpGs(adenylatecyclase-stimulating)gnvtrGTPase.Nlmngncnchcnngca GTPasexctcvgyrashothaGs/adenylatecyclaseludi. Tranducinvgustducin(tnhiunhnvnm)ucADP-ribosylated bi c 2 loi c t trn. Phn ng ny c th c dng phn lp cc G-protein c th b ADP-ribosylated. 3.6.S iu ha tn hiu G-protein[59] RGS Protein [59] RGSproteinthuchccproteinlinktlnglogingnhauvtrRGS 130aminoacidchophpchngbmvotiunvcaG-protein.Khi RGSproteinbmvo,niuhatnhiuG-proteintheo2cch.Cchth nht(quantrngnht),ncvaitrnhGAPs(proteinkchhot GTPase), tngcngsthyphnGTPbngcchhothaG-protein,sauchng kch hot GGTP hay G tng cng s khi phc ca cc phn t tc hiu (effector).RGSproteinkhngnhhngntlGDP-GTPvtlG-proteinckchhotbithth.Cchth2.RGSproteinlmgimkh nngbmcaGGTPvocc phnttchiu,ngnchnphnng.Tac th thy tiu n v c kch hot b GTPS khng thy phn c. V d, RGSprotein,RGS4,ngncnspngcaPLC-1iviGTPSkch hot Gq. C rt nhiu loi RGS protein v vy cng c rt nhiu chn lc cho tng tiunvvcngcnhiutcnglntnghthngtcngkhc. Page39 Nhngthuctnhnythngcnhgitronghthngbiuhinkhi phc. Hin nay vai tr ca RGS protein ring bit trong t bo vn cha c r. MttrongnhngiuthvcavnnylslinktgiaRGS protein v tiu n v c th b ph v bi im t bin trn tiu n v m khng nh hng n chc nng ca G. S kt hp t bin ny vi t bin khc gip loi b tnh nhy cm ca PTx RGS protein ni sinh c vai tr trong vic c ch dng Ca2+ trong thn kinh giao cm bi Go c kch hot binoradrenaline.Vd:sthaythGobngGotbingipgims nhycmcanoradreanalinei10lnvlmchm qutrnhkhingv khiphcscch.Tuynhin,vnnylinquannkhnnghon nguyn ca h gene. Hnh 13: Minh ha mt s vai tr ca RGS protein Page40 Protein hot ha GTPase hot ng nh mt phn t tc hiu [59] EnzymecvaitrnhGAP-tngcngsthyphn GTP,iukhins bt hot nhanh ca cc ezyme c hot ha bi G-protein. V d, Gq-GTP thunchottnhGTPasertyu(tiutn10-60s)nhnghottnhnys tng ln 50 ln khi c mc tiu tc hiu ca n, nh PLC-1 chng hn, iu naylmchochukbnhyhottnhsinhhccanchkoditrong1s. Nhth,sthmvophosphodiesterasertngnchukbnhycaGTP-bound-transducint20sxungcn5s.Tcdngtngcngca phosphodiesterase kthp vitcngvisualRGSc cptrn.Cc tc hiu ca knh ion c vai tr nh GAP khi thiu RGS protein vn cha r c ch. Khiccth thkhnghotng,yuttraoi guaninenucleotide (GEF) lin kt vi tiu n v ca mt protein G heterotrimeric cng ang trng thikhnghotng.Nhng"G-protein"lmtchttamphnca, ,v tiu n v (c gi l G, G, v G, tng ng) c tr li khng hot ng khi nghch rng buc guanosine diphosphate (GDP) (hoc cch khc, khngguaninenucleotide)nhnghotngkhilinktviguanosine triphosphate(GTP).Saukhikchhotthth,lnhvcGEF,lnlt, allostericallykchhotccproteinGbngvictraoimtphntGDP GTPti-tiunvcaG-protein.Cctboduytrmttl10:1ca cytosolicGTP:GDPilyGTPcmbo.Tithiimny,cc tiunv ca G-proteinphntchtccthth,cngnh nhau,mang li mt monomer G-GTP v tng tc cht ch G dimer, m by gi c t do iu chnh hot ng ca cc protein trong t bo khc. Mc m hcthkhuchtn,tuynhin, bhnchdoccpalmitoylationca Gv Page41 s hin din ca mt phn t glycosylphosphatidylinositol (GPI) c lin kthatrthmvoC-trmcuicaG. Phnnaphosphatidylinositolca GPI-linktcchahainhmacylkncmneo btk loi GPIprotein lin kt (v d G) vi mng t bo, v cng c th, mt mc , chic blipidaphng.(SosnhvinhhngcapalmitoylationtrnGPCR ni a ha ni trn) V G cng c GTP GDP kh nng thy phn chm, hnh thc hot ng ca-tiunv(G-GDP)lcuicngtisinh,dochophp reassociation vi mt dimer G hnh thnh "ngh ngi" G-protein, m li c th lin kt vi mt GPCR v ch kch hot. T l thy phn GTP thng tng do cc hnh ng ca mt gia nh ca cc protein iu chnh allosteric giliutittnhiuG-protein,hayproteinRGS,mlmtloiProtein GTPase-Kch hot, hoc GAP. Trong thc t, rt nhiu cc protein quan phn ng chnh(v d nh cyclases adenylate)m tr nn kch hot / bt hot khi tng tc vi G-GTP cng c hot ng GAP. Tn hiu nh vy, ngay c giai on u trong qu trnh ny, GPCR-bt u c kh nng t chm dt. Chi tit 2 con ng truyn tn hiu AMPc v PIP2 SaukhiGPCRbkchthchbiphitthnshothaproteinG, protein G s truyn thng tin vo t bo qua 2 con ng chnh l AMPc v PIP2[2] Page42 4.1. Con ng truyn tn hiu AMPc L trnh tn hiu ca AMPc Hnh 14: M phng s khai hot ng thng qua AMPc. AMPc l mt cht truyn tin th 2 hin din tt c cc c quan trong c th v tham gia vo v s cc qu trnh iu ha ca t bo. S hnh thnh AMPc thng ph thuc vo s hot ha ca protein G ( GPCRs). Protein G l 1 d trimer ha protein , bao gm mt h protein c phn loi da vo cch no lin kt vi mng t bo v c ch hot ha n. H protein ny gip hot ha enzyme adenylyl cyclase (AC). C mt vi cht tc hiu tn Page43 hiuAMPcnhproteinkinaseA(PKA),EPACs(exchangeproteins activatedbyAMPc)ckhnnghothaGTP-bindingproteinRap1v CGCS ( cyclic nucleotide gated channels). Cc cht tc hiu nysau bin thngtinchcnngcaAMPcthnhccpng,nhschuyn hanng lng,sphin mgen,vhot ng caccknhion.Trongnhiutrng hp , nhng chc nng ny c iu bin ( modulation), AMPc s hot ng nhmtchtthitlp hot ngcaccl trnhtnhiukhcvdovyn ngvaitrtrungtmtrongschnglp(cross-talk)giaccltrnhtn hiu vi nhau. Chc nng iu bin ny cng th hin r cc chui tn hiu ca Ca 2+ trong c t bo thn kinh v t bo c. Nhiu hot ng ca AMPc phthucvovtrchnhxccaPKA,linquanticccchttchiu ngcdng(upstream),vxuidng(downstream).MthA-kinase anchoringprotein(AKAPs)quytnhsnhctrongtbocaPKA cngnhlslngthnhphncaltrnhtnhiu.CcphnngOFF- ngttnhiucvaitrgimAMPcthngquaqutrnhthyphnAMPc hoc a AMPc ra ngoi t bo. Page44 Hnh 15: AC t 1 n 9 c phn b rng ri . Ncnhiutrongnonhngcngphnbtrongnhiuloitbo khc. AC10 ch c mt tinh hon. Hot ng chc nng iu ha ca AC1-AC9 thngqua G proteins.Tt cACckchhot biGsnhngchc mt s b bt hot bi Gi. Tiu n v cng c kh nng hot ha vi loi AC v bt hot cc AC cn li. Mt vi AC c iu bin bi mt s l trnh tn hiu khc nh Ca2+ v PKC. Mt vi li b bt hot bi PKA do vy to ra vng tc hi m, khin cho AMPc c th c ch chnh sn phm ca n. S hnh thnh AMPc AMPc c th c to thnh t s kch thch ca rt nhiu cht khc nhau, mthngthnglneurotransmittervhormones.Ttcccchtkch thch u tc ng thng qua h thng GPCRs, c vai tr hot ha hay c chenzymeadenylcyclase(AC).TrongtrnghphothaAC, Page45 Guanine nucleotide exchange factor ( GEF) s thay th GDP bng GTP ti tiu n v , ri phn ly tiu n v ny khi phc hp , v tiu n v s.GTPshothaAC(ngclii,GTPscchAC).Sau GTPase trn tiu n v s thy phn GTP thnh GDP, protein c ti cu trc v qu trnh hot ha AC kt thc. Adenylyl cycase ( AC) H AC bao gm 10 loi : 9 loi trong s l cc protein bm mng ( 1-9), loi th 10 tan trong bo tng. Cu trc domain ca AC1-AC9 tng i ging nhau. Hai domain ln nm trong bo tng l C1 v C2 c cha vngxctc,tothnhcutrcd dimer hav ngtcdngvinhau chuyn ATP thnh AMPc. Hnh 16: Cu trc domain ca ACPage46 AC 1-9 c cu trc domain ging nhau.Mt chui peptide n to thnh cc domain xuyn mng (TM), trong TM1-TM6 c tp hp li cng vi nhau, tng t i vi TM7-TM12. Mi TM u c C1 v C2 c cha cc vng xc tc chuyn ATP thnh AMPc. Lu l AC10 khng c vng xuyn mng nhng vn c C1 v C2 nn vn c chc nng xc tc Cc cht tc hiu thng qua AMPc AMPc l mt tn hiu ni bo c s linh hot cao v c kh nng hot ha nhiu cht tc hiu khc nhau. Mt trong nhng v d ca cc cht tc hiu loinylEPACs,cvaitrhothaRap.Mtnhmtchiukhcl CNGCs ng vai tr quan trng trong h thng cm nhn mi v v gic. Tuy nhinhu ht cc hot ng ca AMPc u thng qua protein kinase A ( PKA). Hnh 17: T chc v chc nng ca l trnh tn hiu AMPc. Page47 AMPcchnhthnhththngACbmmngtbovcACha tan nhy cm bicarbonate. S hnh thnh c iu ha c bi cc agonists hot ha hot ng thng qua tiu n v s v c agonist bt hot i hay tiunv.NngAMPcgiatngnhanhchngvthchinchc nng thng qua ba h thng tc hiu khc nhau. Trong , chc nng chnh caAMPc lhotha PKA phosphorylhamtlnglnccyut trung gianthun chiu. Mt vi qu trnh dn n s phin m gen thng qua hot ng ca AMPc respone element binding protein ( CREB)v hothaccknhion(nhththAMPAvCFTR).Ccyuttrung gianthunchiukhccngcthlGMPcphosphodiesterase(GMPc PDE),phospholamban(PLN)iukhinsarco/endo-plasmicreticulum Ca2+ - ATPase ( SERCA) , th th ryanodine ( RYR) v knh Ca2+ Cav 1.1 v Cav 1.2 Protein kinase A (PKA) NhiuhotngcaAMPccnsthamgiacaPKA-cchcnng phosphoryl ha ti nhng v tr c hiu ca qu trnh tc hiu xui dng. Protein kinase A( protein kinase ph thuc AMPc ) chuyn gc Pi t ATP n gc hydroxyl ca nhm serin hoc threonine , y l phn c th ca trnh t 5-amino acid chuyn bit. Protein kinase A tn ti trng thi tnh cu trc nh sau:-2 tiu n v iu ha (R) -2 tiu n v thy phn (C) Bnhthngmitiu nv iuha caproteinkinaseAcchatrnh t pseudosubstrate( c cht gi ) c th so snh c vi vng cht nn ( substrate domain) ca protein ch ca protein kinaseA, nhng trong cu Page48 trc ca n alanine thay th cho serine hay theronine. Vng pseudosubtrate catiunviuhathiu gchydroxyl dovykhng phosphate ha c,gnvovnghotngcatiunvthyphnvkhahot ng ca n. Khimitiunviuhalinktvi2AMPc,sthayicutrc ca vng ny s dnn vic gii phogns tiu n v thy phn. Hai tiu nvnysaucthphosphorylhathyphnhaserinehoc threonine ca protein ch. R2C2 + 4 cAMP R2cAMP4 + 2C Hnh 18: S lc s hot ha PKA Page49 Lurng,PKIs(proteinkinaseinhibitors)iuhahot ngcatiu n v C Chc nng ca l trnh tn hiu AMPc L trnh tn hiu AMPc iu khin mt lng ln cc qu trnh ni bo, v d nh sau:-AMPcchotngkhngvimmnhbiscchhotngca macrophages v dng bo. -Th thmelanocortin 4 (MC4Rs)trnneuronthhai sdngltrnh tnhiuAMPctnghplnccyutphinmhi( hypothalamictranscriptionfactor)single-minded(sim1)lmgim lng thc n a vo c th gy gim cn. -AMPcc vaitrtrunggian ivicchormone alipidtrongt bo m vng bng cch hot ha lipase nhy cm hormone . -Ssinhnhitcatbomnuciuhabihotngca noradrenaline qua hot ng ca AMPc. -Shothaca DARPP-32cngphi hpvihot ngcaltrnh tn hiun ca dopamine v glutamate trong neuron ty trung gian. -Shothaca DARPP-32cngphi hpvihot ngcaltrnh tn hiu ca dopamine v glutamate trong neuron ty trung gian. -S phn hy glycogen cm ng adrenaline trong t bo c bm xng phthucvosphosphorylha phthucAMPccaphosphorylase kinase. Page50 -ShothacaccyutphinmphthucAMP(CREB)gp phn iu ha s tng hp glucagon trong t bo ty. S phn gii AMPc C 2 cch ngt phn ng ca AMPc. C th;-S thy phn AMPc thnh AMP di tc dng ca phosphodiesterase. -AMPc c a ra khi t bo bng ABCC4, mt loi ATP binding cassette (ABC) 1.2. L trnh tn hiu Phosphoinositide [2] Hnh 19: m phng s khai hot ng ca 1, 4, 5-triphosphate v DAG Cc l trnh tn hiu thng qua cc phosphoinositide lipids rt phc tp bi v n c s tham gia ca mt lng ln cc phn t truyn tin thng qu Page51 c 2 qu trnh tng hp v thy phn ca cc phosphoinositides. Cc qu trnh traoichtlinquan nphosphosinositidecthc phnthnh2loi ln. Th nht l cc qu trnh chuyn ha ca inositol lipid, lin quan n h phntPtdIns-chuynhatoramtlnglnccchttrunggianlipid, mt vi phn t ny l cha kha cho cc l trnh tn hiu quan trng. Th 2 l ccqutrnhchuynhacainositolphosphate,mtltrnhchuynha phctplinquannccinositelphosphatetanctrongnc.Mtvi inositol phosphate c sinh ra bi qu trnh chuyn ha ny ng vai tr l 1 chtdntruyntnhiuctc ng trongl trnh tn hiu a chc nng ca inositol phosphate. PhospholipaseCtorahaithngtinthhai:1,2diacylglycerol( DAG) v nositol 1, 4, 5 triphosphat ( IP3) Nhiu hormonegy tng calci t li ni sinh chtDng tn hiu bt u t GPCR lin kt vi hormonekt hp vi protein G thuc h Gq. Loi protein Gq ny khng tc dng ln adenylat cyclase m n hot ha phospholipase C, enzym ny c hiu vi phosphoglycerol cha inositol. Phospholipse C kch thch bi hormone, tc dng ln phosphatidyl inositol v nhnglipidlinquantrongmngtbo.Phosphatidylinositol4,5 biphosphat l mt c cht quan trng nht v n c tch ra thnh 2 thng tin th hai: 1, 2 diacylglycerol ( DAG) v IP3 DAG Vchtantronglipid,litrongmngvcthkhuchtnngang tronglpdilipidcamng.ViscmtcaCavphosphatidylserin. DAGhothaenzymeproteinkinaseCkthpvimng.Cngnh proteinkinase A, protein kinase C phosphoryl ha serin v threonine ca chi Page52 ngang ca protein . Mc d mt s protein c th c phosphoryl ha bi c 2 protein kinase A v C, s c hiu ca c cht ca 2 kinase hon ton khc nhau. IP3 IP3 lmtthngtinhatantrongnc , cthkhuchtntrong bo tng.IP3lmtngCabotngnhmknhCacalinisinhcht. Knh c m ra v mt lng ln Ca c vo trong bo tng. C th IP3 cngmknhCamngtbo,aCacthngxuyntrong phospholipidmtngoimngtbovotrongbotng.Hunh,chc nng c nht ca IP3 l gy tng nng Ca trong bo tng, , nng Ca thp hn 15000 ln so vi Ca khu vc ngoi t bo. trong bo tng, nhng ion Ca c nhiu tc dng, kt hp vi nhiu protein .CAM(calmodulin),mtproteinchacalcicttcnhngtbo eucaryotkthpviCatophchpCa2+-CAMhothachuinhca myosinkinasegycocbngcchphosphorylhamtcpchuinhca myosin. Page53 Phn 3: nh hng nghin cu thuc mi Vi vai tr m nhn nhng chc nng quan trng, s tm hiur c ch hot ng ca GPCRs gip m ra hng i mi trong nh hng sn xut thuc. l sn xut cc thuc tc ng vo cc qu trnh truyn tin caGPCRs.Ngy naycc thuc loinylcc thucbnchynht (v tcdngngmctiu,gimtcdngph)vGPCRlchngmca hn 40% cc loi dc phm hin nay.Cc sn phm ng ch bao gm Zyprexa(caEliLilly),Clarinex(Schering-Plough),Zantac (GlaxoSmithKline), vZelnorm (Novartis) [60][61] ng dng trong sn xut thuc mi. Vi vic khm ph ra cu trc, vai tr, qu trnh hot ng ca GPCRs, BrianK.KobilkavRobertJLefkowitzgipccnhkhoahc tm ra hng i iu ch thuc mi tt hn, tc dng ng ch hn do t gy phn ng ph bng cch: iuchthucccuto phntthch hp( datrncutrc bit ca GPCRs, ca cc phi t, cc thnh phn trong c ch truyn tn hiu ca t bo) Datrn qutrnhcbnha sinhvsinhl, xc nhcnsn xutthuctcngmc tiukhunotrongqutrnhtruyn tn hiu ca t bo. iu ny hon ton mang tnh kh thi cao v c chng minh trong thctintrongvicphtminhrapropanolol(thucchnBeta)v Page54 cimetidine(thuckhnghistamine)canhkhoahcBlack(Nobel 1988)[1]a.Nguyn tc tm thuc trong iu tr.- Nguyn tc iu tr: Nh bc hc Daniel Bovet ( Nobel 1957) t ra nguyn tc tm cc cht i khng. -Nguyn l:+tnh ng hnh lp th ( isosterism ) v s cnh tranh ( competition 0 gianhngchthucccutrctngtnhaunhnglictc dng cnh tranh ganh ua hay i khng vi nhau.+isosterism=nghnhlpthlnhngchtmvmtphntc cngsnguyntvcngselectronhatrchonncnhngc tnhvtlgingnhau.Nhnghachtnghnhlpthdoctnh tng t v c tnh ha hay l nn cng c nhng c tnh dc ng hc ging nhau. +ngBovetvcngsnhnthycnhngreceptorchiuvi cht sinh hc trong c th v ra khi nim kha v cha . Nhvndngkhinimkhavchamccnhkhoahcnhngii thng Nobel 1988 c c s tm ra thm nhiu th thuc c hiu qu ng gp thnh tu cho nhn loi. b.Khm ph, pht minh ra propanolol v cimetidine. Cc giai on khm ph ra ha cht propanolol ( thuc chn beta) -TrongbithuyttrnhnhngiicaJameW.Black(Nobel1988): Ccthuctcchormone*gimlc,nhngnguynlcasi Page55 khngcngh(Drugfromemasculatedhormones,theprinciplesof syntopicantagonism)mtrtrccgiaioncakhochtmti dn n khm ph ra ha cht propanolol Hormon * dng vi ngha rng theo James Black l mi cht tit ca t bo c tc dng ln t bo khc. -Do nhn thy cc thuc iu tr v chn on nhi mu c tim thi ( dng oxy cao p hay nitroglycerin iu tr, dng adrenalin lm test chun on l tim vn c tng nhp, tc l c adrenalin ni tit, dn Black ti ngh l cn lm gim bt tiu th oxy do tng nhp y c tim ang b thiu mu. -Nm 1948 nh khoa hc Alquit chng minh vi adrenalin c 2 loi receptor , * m isoprenalin l cht kch thch receptor . Receptor c mch c vnn, da, mt, rut c tnh kch thch lm co c trn tr thnh rut th gin. Receptor ctnh chtcchlmgin, trtimlilm pnhanhv mnh. -Nm 1956, nh khoa hc Black thy cn tm ra mt cht c tac dng c ch c hiu vi receptor -Nguynlcstmrathucchngreceptorlnguynlng hnh lp th ca Bovet. -Blackthrtnhiuloithucthnghimtrnchutlang.Ban u th trntimclp,sau ginguynchtun hon o chuyt p v sau cng nh gi qua c nh ca tim. Page56 -ngtnghpcchtctcdngchngliadrenalinnhcht DC1, mt cht tng t nh isoprenalinnhng u khng c kt qu. -Saucng ng chrac mt chttngtkhc dothmnaphtyl voisoprenalincgilpronethalol.ngthnhcng.Vkt qunhmongmun:khngtngcothtctmnhlntmthtca convthn m,chtkhnggytngnhptimkhikchthchtrnthn kinh giao cm hay bng isoprenalin. -Nm 1964, tng t nh nguyn tc tm ra thuc chn beta , bng cch ko di chui cnh 4 C v thm nhm cyano-imino vo nhn histamine thcchphmcimetidinctcdngchngreceptorH2vi histaminec. ngha v minh chng cho nghin cu ng dng ca protein G. Trong kt lun nh khoa hc Black tin on sinh hc phn t s cung cp con ng n gin cho vic nghin cu cc thuc hin i bng cch tchbitvbiulcaccreceptorcacchthng.Khngcnnghi nggnalsinhhc phntaramtconngyha hntrc tipvphongphhnbaogiht,cchsnglchachtivicc receptor hormone Thc vy, y l iu quan trng nht v c th ni Black m hngi michonghincuthucmivothicangvthnhcngcang cnglminhchnghnghnchovicngdngcaGPCRstrongsn xut thuc vai tr ca chng trong thng tin tng tc vi nhau cng nh cc bin php tng cng hay c ch chng trong y sinh hc. 2.Trong iu tr bnh ung th [62] [39] Page57 H th th cp i vi protein G (GPCRs) l h th th ln nht trn b mttboclinquantiqutrnhtruyndntnhiu.Ccnghin cu gn y cho thy vai tr quan trng ca chng trong pht trin khi uvdicn.Tboctnhthngchimquyniukhinccchc nng sinh l bnh thng ca GPCRs tn ti, sinh si ny n t ch, ntrnhhthngmindch,tngcungcpmucah,xmlncc m xung quanh ca h v ph bin n cc c quan khc. nh gi ny s gii quyt s hiu bit hin ti ca chng ti trong nhiu vai tr ca GPCRs v mch tn hiu ca h trong khi u tin trin v di cn. Chng ti cng s tho lun v cch can thip vi GPCRs c th cung cp c hi duy nht ngn nga bnh ung th v iu tr. Chititqutrnhtruyntintrongt boca b3phchpphi t - th th - protein G. Page58 Hnh 20: Tc dng ca cc loi protein G CcphitsdngccththG-protein-coupled(GPCRs)kchthch mc tiu l mng t bo, t bo cht v nhn.GPCRs tng tc vi protein G ( gm 3 tiu n v , , ),tiu n v lin kt vi GDPv ang trng thi ngh. KhichtchvnlinktviGPCRssgyramtsthayicutrc cc th th, v GDP c phn ly ra v thay vo l GTP s lin kt vi tiu n v .Cc tiu n v protein G c chia thnh bn phn h: G s, G i, G Q v G12,vmiththGPCRcthbtcpvi1hocnhiuphnhca protein G . Mi mt phn h ca protein G s kch hot nhiu hn 2 hiu ng.Page59 Thng G s kch thch cyclase adenylyl v lm tng nng ca AMP vng (cAMP), trong khi G i c ch cyclase adenylyl v lm gim nng cAMP, vGQkchhotphospholipaseC(PLC),phnctbisphosphate phosphatidylinositol (PIP2) vo diacylglycerol v inositol triphosphate (IP3).Cctiunv Gcchcnngnh mt dimer kchhotcc phnttn hiu, bao gm phospholipases, cc knh ion v lipid kinase.Ngoi chc nng truyn tin th 2 , cc tiu n v ca protein G nhG 12 vGQcngcthkimsothotngcaccphntcvaitrquan trngtrongtruyntnhiunibo,baogmproteinlinktviGTP,cc protein kinase mitogen kch hot (MAPK) , cckinase serine-threonine, ... NhproteinGcthkimsotnhiuchcnngcatbo,vcchot ng khc thng ca protein G v cc tc ng th cp ca n c th ng gpchostintrinungthvdicn. Nuiuchthuckimsotchc nng ca protein G th s ngn chn c s tin trin ca ung th. 3.Trong iu tr bnh tim [63] Page60 Hnh 21: Vai tr ca GPCR vi iu ha Ca Nguyn l sinh hc:Khi kch thch protein G ( Gs) th kch thch andenylyl cyclase do tng sinh AMPc dnti nhiuCa++ voni bogy tim co bp. Nuprotein G b c ch ( Gi) th tc dng ngc li. C ch nghin cu thuc: Sn xut thuc lm sao cho tch cp gia receptor v protein G nh vy s khng c qu trnh truyn tin tip theo. HoccchmenproteinkinaseA(PKA)dntikhnghotha knh Ca++v t bo tim s khng co bp. 4.Trong iu tr bnh do virut [64]Virus s dng nhiu phng php tip cnGPCRs v khai thc con ng truyn tn hiu ni bo ca GPCRs.D dng cch tip cn vi GPCRs g th cui cng mc ch cng l m bo thnh cng snhn ln ca virus v thng xuyn ng gp vo bnh l do virus gy ra. V d nh virus HIV c kh nng thc y s di c ca bch cu qua lm tng s pht tn virus S hiu bit su sc v cc qu trnh sinh ha trong bnh l do virus gy ra s to iu kin tt cho s pht trin cc chin lc iu tr chng li virus. Page61 5.nh hng nghin cu ng dng thuc tc ng vo protein G. Protein G nh 1 mc tiu mi trong iu tr tim mch. ProteinGlinquannquynhchcnngnim,scthtctrn,s tng trng, s hot ng cng nh s ph i tim mch. Mc tiu protein G v tn hiu xui dng ca chng c th ha hn phng php iu tr ri lon tim mchnhxva dngmch,hpvantim,tnghuytp,cothtmch, ph i tim. Nghin cu t phng th nghim v lm sng cung cp nhng bng chng rngproteinGcngviccchttcnglnchnglinquanncch bnh sinh ca cc bnh tim mch khc nhau. S r rng cu trc protein G v nhngnhnttcngtronghthngtimmchschoktqulspht trin ca cc cht c ch c bit nh c ch ROCK v c ch isoprenylation. Mt s trong nhng loi thuc ny c nghin cu rng ri cho cc ng dng trong ung th nhng gn y chng c th nghim trn m hnh ng vt khc nhau vi cc bnh l tim mch. [65] Protein ng dng trong tm thn hc. ProteinGngvaitrtrongvictipnhn,phnphitnhiutronghot ng dn truyn thn kinh ca h thn kinh trung ng. Protein G l c s hi nhptnhiutrongthnkinhtrungng,vlmchotbothnkinhc chcnngadng.Sbiuhinbtthngtrongchcnng proteinGlin quanntnhtrngtmthn.Mtslnglnthuctcnglnhthn kinh thng qua protein G. Hiu bit c ch tc ng ca protein G trong hot Page62 ng ca h thn kinh c th l cha kha pht trin cc thuc mi c v tr c hiu, da trn protein G[66] KT LUN V KIN NGH QuanghincugiiNobelHahc2012,tahccrtnhiuv tinhthnlmvic qunmnhcaccnh khoahc.Bncnh lcc c tnhcnthitcamtngilaong mi:cnc, chmch,sngto,kin tr, nhn ni, cn thnGii Nobel Ha hc gip chng ta hiu r c ch phntcaccqutrnhtruyntnhiutrongtbo,cchthccctbo giaotipvinhau,vaitr quantrngca GPCRstrongccqutrnhtruyn tin .Qua nh hng phng php ch to dc phm da trn c ch ca cc qu trnh truyn tin ny.1.Trongkhunkhlunvn,chngtilmrcccim sau: Phn c s. -Cu to, c ch hot ng, vai tr ca GPCRs. - Chi tit m hnh truyn tin phc hp 3 thnh phn ( phi t , GPCRs, protein G). -HaiconngtruyntnhiubkchhotbiGPCRslAMPcv Phosphoinositide. -Ccyutnhhngtiqutrnhtruyntnhiubkchhotbi GPCRs. Phn ng dng. Page63 - nhhngphng phpchto dc phmdatrnnguyntcng hnhlpth(snxutccchthahcccutrctngngviphit nhvychngscnhtranhviphitgnvoreceptorvaratc dng mong mun ). -nhhngsbphngphpsnxutthuctimmch,thucchng ung th, thuc chng virut da trn c ch phn t ca qu trnh truyn tin do GPCRs kch hot. 2. Khuyn ngh cc lun vn tip theo khi nghin cu v GPCRs. Tm hiu su hn v c ch truyn tin phn t GPCRs trong cc bnh l tim mch, ung th, virut, tm thn ( parkison),.Hng sn xut thuc tc ng vo yu t no trong qu trnh truyn tin cc bnh ny. Nu r hn c ch tc dng, phng php bo ch ca cc loi thuc ngdng thnhcnghiu bitv GPCRs chto hinnay:Zyprexa(ca EliLilly),Clarinex(Schering-Plough),Zantac(GlaxoSmithKline),vZelnorm (Novartis) gip hiu bit su hn v cch thc ng dng v xu hng iu ch thuc tin tin hin nay. TI LIU THAM KHO Ti liu ting Vit 1. Gs. V Triu An( 2007), Gii thng Nobel Sinh l hay Y hc t nm 1901 n nm 2007 , NXB Y hc. 2. GS. L c Trnh ( 2012), Hormon v Ni tit hc ; Ni tit hc phn t, NXB Y hc. Ti liu ting Anh 3. 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(1998)."Activation of G protein-coupled receptors entails cysteine modulation of agonist binding". Journal of Molecular Structure (Theochem) 430: 5771. 56.http://www.bio-balance.com/ 57.Chun Ming Teoh, John Kit Chung Tam, Thai Tran. Integrin and GPCR Crosstalk in the Regulation of ASM Contraction Signaling in Asthma. J Allergy (Cairo). 2012; 2012: 341282. Published online 2012 September 29. 58. Millar RP, Newton CL (January 2010). "The year in G protein-coupled receptor research". Mol. Endocrinol. 24 (1): 26174. PMID 20019124 59. John C. Foreman, Torben Johansen ( 2003), Text bookof receptor pharmacology Second Edition 60. Filmore, David (2004). It's a GPCR world. Modern Drug Discovery (American Chemical Society) 2004 (November): 2428. 61. Susan R. George, Brian F.ODowd ,Samuel P. Lee . G-protein -coupled receptor oligomerization and its potential for drug discovery 62. Venkatakrishna Rao Jala1 , Brandie N Radde, Bodduluri Haribabu,Carolyn M Klinge . Enhanced expression of G-protein coupled estrogen receptor (GPER/GPR30) in lung cancer Jala et al. BMC Cancer 2012, 12:624 63. http://www.cvphysiology.com/Blood%20Pressure/BP011a.htm 64. Akrit Sodhi, Silvia Montaner,J. Silvio Gutkind. Viral hijacking of G- protein coupled receptor signaling networks 65. Manji H., K. (1992), G-protein imolication for psychiatry , Am J Psychiatry, 149 (6), 746-760 66.Lucy G. Andrew (2008) , Telomerase inhibition, Humana Press, 1-8 67.The Nobel Prize in Chemistry 2012 Advancde release 68.The Nobel Prize in Chemistry 2012 Popular release Ph lc 1: Gii thiu v gii thng Nobel. Ngy21-10-1833,AlfredBernhardNobelchoitiStockholm (Thyin),tronggianhcnhiungilks.Thitr,nginhiu ni trn th gii v thng tho 5 th ting. T nm 1860, trong nh my ca cha,ngbtuthnghimchthucnbngnitroglycerin.Nm1867, Nobelccpbngsngchcholoithucncngttnl dynamite ny v sau xy nhiu nh my khp th gii, sn xut thuc n cung cp cho cc cng ty khai thc m, xy dng v qun i.ng cn c nhiu nghin cu c gi tr khc v cao su nhn to, da, t, qu... Nobelcngyuthchvnhcvtngvitmtstiuthuyt,th, kch... Ngy 27-11-1895, ti CLB Thy inNa Uy Paris (Php), Nobel k di chc cui cng, mt nm trc khi ng qua i v bnh ti nh ring San Remo(Italia)ngy10-12-1896.Theodichc,nglitonbgiasn tngng9triuUSDvlisutcansdnglmgiithnghng nm mang tn ng, trao cho nhng c nhn c cc nghin cu em li nhiu li ch nht cho con ngi trong cc lnh vc ha hc, vt l, sinh hcy hc, vn hc v ha bnh. Nm1900,HiphiNobel,mttchctnhn,cthnhlp qunl tisnc Nobel dichc lmgiithngcho nhngcnhn ot gii.Giithngquctdanhginybtuctraohngnmtnm 1901.Tnm1968,cthmgiiNobelkinhtdoNgnhngTrungng Thyinlp. Ccgii Nobelu traochocnhn,chNobelhabnhc th trao cho c nhn hoc t chc. Gii thng cng b hng nm vo thng 10 v c trao vo ngy 10 thng12,ngyknimngymtcaNobel.Giithngbaogmtin thng,mthuychngvngvmtgiychngnhn.LtraogiiNobel ctchctiStockholm(Thyin),ringltraogiiNobelHabnh din ti Oslo (Na Uy). Huy chng Nobel Vt l v Ha hcHuy chng Nobel Vn hc Huy chng Nobel Ha bnh Huy chng Nobel Kinh t Nobel sinh l hay y hc Giy chng nhn t gii Nobel ca 2 nh khoa hc Brian K.Kobilka v Robert J Lefkowitz Ph lc 2 Con ng nghin cu h th th bt cp vi Protein G ( GPCRs) ca 2 nh khoa hc. 1.Tiu s 2 nh khoa hc t gii Nobel Ha hc 2012. Nh khoa hc Robert J. LefkowitzRobertJ.Lefkowitz sinhngy15thng4nm1943,lmtnhyhcni tingngiMnitingvi ththbtcpviproteinG.nghinang lm vic trung tm y khoa i hc Duke . RobertJ.Lefkowitzsinhravongy15thng4nm1943ti Thnhph New York trong gia nh Do Thi. Sau khi tt nghip trngtrung hc khoa hcBronx,ngtheohc ColumbiaCollege vnhncbngcnhn nm 1962. ng tt nghip bng bc s ti i hc Columbia ngnh bc s v bc s phu thut trong nm 1966. ng hon tt nghin cu y hc v cc bnh timmchtrongthigianlmvictiBnhvinakhoaMassachusetts thuc ihcHarvard tnm1970nnm1973.Nm1982,RobertJ. LefkowitzcphonglmgiosYkhoatiTrng ihcDuke (M). ng cng gi hc hm gio s Sinh ha. Gio s Tin s Robert J. Lefkowitz tng t nhiu gii thng danh gi v y khoa, bao gm Gii thnh tu nghin cu ca Hip hi Tim mch M (2009) v HunchngKhoahcQucgia (2007).RobertJ.Lefkowitzchuyn nghincuvditruyn.Thng10nm2012,ngctrao giiNobelha hc nm 2012 cng vi Brian K.Kobilka. ng c bit nhiu v nghin cu miu t c tnh c th ca cu trc v chc nng ca th th -adrenergic v cc th th lin quan khc. Nh khoa hc Brian K.Kobilka. Brian Kobilka (sinh ngynm 1955)lmtnhhchcvsinhhcngi MgcBaLan. nghinl giosTrng ihcStanford,ngthil nhngsnglpCngtyCngnghsinhhcConfometRxv ththbt cp vi protein G.BrianKobilkattnghipcnhnsinhhcvhahcti ihc Minnesota (HoaK),saulybng tins ykhoati ihcYale.Brian Kobilka ni ting vi nhng nghin cu ca ng v th th bt cp vi protein G, ng t c nhiu gii thng nghin cu khoa hc danh gi ca M, chnghnnhGiithngThnhtunghincukhoahctphca nmvonm2007.Thng10nm2012,ngctrao giiNobelha hc nm 2012 cng vi Robert J. Lefkowitz. 2.Qu trnh tm kim v pht hin GPCRs. (65,66) Phnlnnhnghiubitcachngtangynayvccctnhco ca th th 7TM c pht hin t cc nghin cu trong 40 nm va qua. Tuy nhin, rhodopsin c xc nh nh l mt sc t nhy sng t nhng nm 1870svphitha trcantrnmngvng mc ccngbvo nm 1933 (3). Trong lch s nghin cu th th c hot ha bi phi t c m t hn 1 thk trc, khi cc nh khoa hc cho rng nhng t bo hotngucmtchttipnhnnmtrnbmt(4,5).Trongccth nghim ban u, cc m c chun b v o kh nng phn ng i vi cc cht kch thch (agonists) v cht c ch (antagonists). Trong mt na th k sau(khongt1920-1970),hcthuytththcincxydng datrnnhlut tcdngkhilng(lawofmassaction)vd liuphn ng ph thuc liu lng (6). Mt s thnh phn ca con ng truyn tn hiu t bo c m t chi tit mc phn t trc khi c nhnghiu bit r rng vthth. l chttruyntnhiuthcpAMPvng(cAMP)vccenzymeadenylyl cyclase (7), cc enzyme kinase ph thuc cAMP (8) v protein G (9-11). Bn cht ca cc th th c hot ha t phi t vn cn gy tranh ci cho nnhngnm1970s.Stnticanhngththnhlnhngphnt ringrbthchthcvthmchcnhngginhchorngththv enzyme adenylyl cyclase l mt protein duy nht. Tnghpha hccc kchthchtcnh duphng x trthnh bng chng thc nghim cho vic tn ti ca cc th th v tr thnh phng phpdtmvhinthccththtrnmngtbo.Ngiutinthnh cngbngphngphpnylLefkowitz,ngibinihormone adrenocorticoviiodinenhduvquanstcvicchtnybmln mngcatuynthngthn(12,13).Sau,ngtptrungnghincuth th ca epinephrine (hay cn gi adrenaline). Nhmnghincutcbctinlntiptheotrongthpnin 1980s.Mictuyndng,Kobilkanhnsthchlmthnotch c cc gen m ha th th -adrenergic t b gen khng l ca con ngi. Bng phng php tip cn sng to ca mnh ng ta t c mc tiu.Trong b gen ca con ngi c khong 1000 gen m ha cho cc th th bt cp vi protein G(1,2) . Khi cc nh nghin cu phn tch gen, h pht hin ra rng cc th th l tng t nh mt mt bt nh sng. H nhn ra rng c mt h th th u ging nhau v hot ng cng mt cch thc.Hin nay, nhm th thnycgilnhmththgnktproteinG(G-protein-coupled receptors). C khong c ngn gen m ha cho mi th th nh th, v d nh, vinhsng,muv,mihng,adrenalin,histamine,dopaminev serotonin. Mt na cc loi thuc men t c hiu qu nh cc th th gn kt protein G ny. Epinephrinelmthormonequantrngvlchtdntruynxungthn kinh c nh hng n nhiu qu trnh sinh l vd. iu ha nhp tim v huyt p. Cc t bo phn ng vi epinephrine u c th th trn mng c trng (gi l th th adrenaline) dng tng tc vi phn t hormone. C t nht 9loiththadrenalinekhcnhaucxpvonhmththalpha-hoc beta-. Cc m v c quan khc nhau s phn ng theo cc cch khc nhau khi nng epinephrinetngcao.Mtthnh cng quantrnglc bygi lkhi phi t c nh du cho php xc nh mt cch c hiu cc th th loi beta (14-16). Lnh vc nghin cu ny c nhn rng, hng lot cc phi t nh du vi tnh c hiu ca n c tng hp d tm mt lng ln cc th th tng ng. Cc phi t nh du cng c s dng nh lng v so snh hot ng ca mt lot cc hp cht c tnh adrenaline i viccththnhmbetavenzymeadenylylcyclase.Nhngnghincu nhit ng hc qu trnh bt cp gia phi t v th th lin kt G-protein cung cp nhng hiu bit su hn v qu trnh truyn tn hiu t bo (17, 18). Nm 1980, mt c ch chung m t qu trnh hot ha th th, cn gi l m hnhphch3thnhphn(17)cLefkowitzvcngslAndreDe Lean v Jeffery Stadel xy dng. Ba thnh phn l (1) phi t ngoi bo, (2)GPCRxuynmngv(3)G proteinngvaitrhothatnhiu(17). Cc phi t (c th l hormone, cht truyn xung thn kinh, hp cht c mi .v.v)bm ln phnngoi bocaththtrongkhi G-proteinlinktvi phn ni bo ca th th. Qutrnhtruyntnhiuththhotngtheocchiuhadlpth (allosteric)vviclinktdlpthctcngquali,tunthccnh lut nhit ng hc. Vic phi t lin kt vi th th lm tng i lc ca phn th th ni bo i vi G-protein. ng thi vic lin kt vi G-protein cng lmtngcngcngilccaththiviphit(17).Sau3thp ninnghincu,chngtabitchititvcchtruyntnhiuxuyn mngthngquaGPCRvcccchiuhalinquan.Mttrongnhng nggpmangtnhquantrnglkhiKobilkavcngsxydngcu trc 3 chiu vi phn gii cao ca mt phc h 3 thnh phn y chc nng bao gm th th beta ca adrenaline (AR) trong phc h vi phi t v G-protein ca n(19).Hnna,trongnm 2011, Kobilkat cmt t ph,ngvnhmnghincucangchpc hnhnhthth-adrenergicngay chnh thiimnc kchhot bimthormone vgi mttnhiuvotbo.Hnhnhnylmtkittcphnt-ktquca nhiu thp k nghin cu. Hnh 22:CutrctinhthcareceptorBeta-adrenergic(AR)trng thi hot ng . Hormon ( mu vng)gn vo v tr pha ngoi ca AR vprotein G ( mu cp i vi AR v tr bn trong.