分子生物學(xué)教學(xué)課件：CHAPTER 19 Gene Regulation during Development

1、發(fā)育生物學(xué)是發(fā)育生物學(xué)是近年來進(jìn)展最快的學(xué)科之一nNature 及其分支雜志在1994年1月2004 年8月期間刊登了1200多篇發(fā)育方面的論文。 nScience 1994年1月2004年8月期間刊登了1050多篇發(fā)育方面的論文。n在Pubmed上可以檢索到46.8萬篇發(fā)育相關(guān)的論文。Developmental biology is at the core of all biology.It deals with the process by which the genes in thefertilized egg control cell behavior in the embryo an

2、dso determine its pattern, its form, and much of itsbehavior. The progress in developmental biology inrecent years with the applications of advances in celland molecular biology, has been remarkable and anenormous amount of information is now available.n張紅衛(wèi)等主編，發(fā)育生物學(xué)， 2001。n樊啟昶等主編，發(fā)育生物學(xué)原理， 2002。n桂建芳等

3、主編，發(fā)育生物學(xué)， 2002 。nLewis Wolpert， Principles of Development, Second edition，2002。nScott F Gilbert，Developmental Biology, Seventh edition，2003。主要參考教材刊登發(fā)育方面論文的主要雜志刊登發(fā)育方面論文的主要雜志nGenes and Development，nDevelopmental Cell，nDevelopment,nDevelopmental Biology,nMechnisms of Development,nAnnual Reviews of Cell

4、 and Developmental Biology,nCurrent Opinion in Genetics and Development.發(fā)育生物學(xué)的研究對象發(fā)育生物學(xué)的研究對象n發(fā)育生物學(xué)（developmental biology）是應(yīng)用現(xiàn)代生物學(xué)的技術(shù)研究生物發(fā)育本質(zhì)的科學(xué)，主要研究多細(xì)胞生物體從生殖細(xì)胞的發(fā)生、受精、胚胎發(fā)育、生長、衰老和死亡即生物個(gè)體發(fā)育（ontogeny）中生命過程發(fā)展的機(jī)制。同時(shí)，發(fā)育生物學(xué)也研究生物種群系統(tǒng)發(fā)生（systematics development）的機(jī)制。n與傳統(tǒng)的胚胎學(xué)（embryology）不同，發(fā)育生物學(xué)是在20世紀(jì)50年代以后，由于分子

5、生物學(xué)、細(xì)胞生物學(xué)、遺傳學(xué)以及生物化學(xué)等其他生命學(xué)科的發(fā)展，并與胚胎學(xué)的相互滲透，才逐漸發(fā)展和形成的一門新興的生命科學(xué)。n傳統(tǒng)的胚胎學(xué)是研究從動(dòng)物受精到出生之間有機(jī)體的發(fā)育，即胚胎發(fā)育。但有機(jī)體的發(fā)育在出生后并未停止，甚至大多數(shù)成年生物體也依然繼續(xù)發(fā)育。隨著生長的進(jìn)行，人類胚胎在大小和形態(tài)上都發(fā)生顯著的變化。人類身體各部分生長的速度并不相同，九周以后身體其他部位的生長速度超過了頭部。一些動(dòng)物能夠再生出失去的器官。一種蜥蜴（South eastern five-lined skink,東南五線石龍子）在防御中丟棄自己的尾巴。 有尾兩棲類蠑螈晶狀體的再生n發(fā)育生物學(xué)的形成和發(fā)展本身是多學(xué)科相互滲透

6、的結(jié)果，代表了現(xiàn)代生命科學(xué)的結(jié)晶。n發(fā)育生物學(xué)既是重要的基礎(chǔ)生命科學(xué)，其研究成果又具有廣闊的應(yīng)用前景，已經(jīng)成為當(dāng)代最活躍的生命科學(xué)研究領(lǐng)域之一。發(fā)育生物學(xué)研究的主要任務(wù)發(fā)育生物學(xué)研究的主要任務(wù)n個(gè)體發(fā)育的基礎(chǔ)是細(xì)胞分化（cell different-iation）。從個(gè)體發(fā)育的角度來說，一個(gè)單細(xì)胞受精卵如何通過一系列的細(xì)胞分裂和細(xì)胞分化，產(chǎn)生有機(jī)體內(nèi)所有形態(tài)和功能不同的細(xì)胞，這些細(xì)胞之間又如何通過細(xì)胞之間的相互作用共同構(gòu)建各種組織和器官，建成一個(gè)有機(jī)體并完成各種發(fā)育過程，這些都是發(fā)育生物學(xué)的主要任務(wù)。n從另一個(gè)角度來講，發(fā)育是遺傳信息按一定的時(shí)間和空間順序表達(dá)的結(jié)果。發(fā)育具有嚴(yán)格的次序性，發(fā)育

7、并不是個(gè)別基因的表達(dá)，而是眾多基因表達(dá)在時(shí)間和空間上的聯(lián)系和配合。n發(fā)育生物學(xué)的主要任務(wù)是研究生物體發(fā)育的遺傳程序及其調(diào)控機(jī)制。Chapter 19by which Cells Are Instructed to Express Specific Sets of Genes during DevelopmentuExamples of the Three StrategiesuThe Molecular Biology of Drosophila EmbryogenesismRNA serve as a critical regulatory moleculeThey are transpor

8、ted along elements of the cytoskeleton which have intrinsic polarityThe transportation is realized by an “adapter protein”“Adapter” proteinsContaining two domainspOne recognizing the 3 UTR of the mRNApThe other associates with the components of the cytoskeletonThereby it crawls along the actin filam

9、entnThree steps:1.The synthesized signaling molecules are deposited in the membrane or secreted into the extracellular matrix.2.They are recognized by the receptor on the surface of recipient cells3.The changes in gene expression in the recipient cell is achieved through the signal transduction path

10、waysb.Activated receptor cause the release of DNA-binding protein so it can enter the nucleus, regulate gene transcription.c.The intracytoplasmic domain of the activated receptor is cleaved to enter the nucleus and interact with DNA-binding protein.Gradient of Secreted Signaling Molecules Two concep

11、ts:nPositional information: a cells development is influenced by its location within the developing embryo.nMorphogens(成形素，形態(tài)發(fā)生素成形素，形態(tài)發(fā)生素) signaling molecules that control position informationb.Cells located near the source of morphogen receive high concentration of the signaling molecule, experienc

12、e peak activation of receptorsc. determine most regulatory protein enter the nucleus;d. The different levels of the regulatory factor lead to the expression of different sets of gene.1.The Localized Ash1 Repressor Controls Mating Type in Yeast by Silencing the HO gene2.A Localized mRNA Initiates Mus

13、cle Differentiation in the Sea Squirt Embryo3.Cell-to-Cell Contact Elicits Differential Gene Expression in the Sporulating Bacterium4.A Skin-Nerve Regulatory Switch Is Controlled by Notch Signaling in the Insect CNS5.A Gradient of the Sonic Hedgehog Morphogen Controls the Formation of Different Neur

14、ons in the Vertebrate Neural Tube1.mRNA localization2.Cell-to-cell contact3.Signaling through the diffusion of secreted signaling molecules1. The Localized Ash1 Repressor Controls Mating Type in Yeast by Silencing the HO geneYeast lifecycle1.Budding 2.Conjugation 3.Spore alter the nucleosomeActive o

15、nly at correct stage of cell cycle1. Mating Type in Yeast by Silencing the HO genenA haploid yeast cell budding to produce a mother cell and a smaller daughter cell.nThe daughter cell cant switch due to localized Ash1 repressor, it cant express HO which initiate switching.nThe mother cell can switch

16、: it lacks Ash1,and is able to express HO.2.A Localized mRNA initiates Muscle Differentiation in the Sea Squirt EmbryonMacho-1 mRNA is ninitially distributed nthroughout the cytoplasm of unfertilized eggs but becomes localized to the vegetal(bottom)region shortly after fertilization, ultimately inhe

17、rited by two cells of the eight-cell embryos,thus the two cells go on to form the tail muscles.3. Cell-to-Cell Contact Elicit Differential Gene Expression in the Sporulating Bacterium, B. subtilis1.1.芽孢形成過程芽孢形成過程 2.2.形成過程中基因活性的調(diào)控形成過程中基因活性的調(diào)控: : 特異特異亞基控制基因組活性亞基控制基因組活性 a. SpoOA 對外界刺激產(chǎn)生應(yīng)答對外界刺激產(chǎn)生應(yīng)答決定芽孢是

18、否決定芽孢是否/何時(shí)形成何時(shí)形成 b.前孢子和母細(xì)胞中的前孢子和母細(xì)胞中的亞基級(jí)聯(lián)亞基級(jí)聯(lián)時(shí)間依賴的變化時(shí)間依賴的變化 c. 細(xì)胞細(xì)胞-細(xì)胞間的信號(hào)傳導(dǎo)：細(xì)胞間的信號(hào)傳導(dǎo)： 位于隔上的受體位于隔上的受體前孢子和母細(xì)胞中事件的協(xié)調(diào)前孢子和母細(xì)胞中事件的協(xié)調(diào) 3. Cell-to-Cell Contact Elicit Differential Gene Expression in the Sporulating Bacterium, B.subtilisA A 和和H H亞基亞基E E 和和F F亞基亞基Figure 12.20 Role of SpoOA in Bacilius sporula

19、tion激活激活E E 和和F F 的表達(dá)基因的表達(dá)基因 A A：F F 激活激活結(jié)果：結(jié)果： E E 是母細(xì)胞特異的是母細(xì)胞特異的 F F 是前孢子特異的是前孢子特異的前孢子中的前孢子中的F F 和和母細(xì)胞中母細(xì)胞中E E 被激活被激活亞基級(jí)聯(lián)亞基級(jí)聯(lián)F F G G ：識(shí)別芽孢分化后期識(shí)別芽孢分化后期要轉(zhuǎn)錄的基因（要轉(zhuǎn)錄的基因（SpoBSpoB）SpoFSpoF K K： 指導(dǎo)母細(xì)胞后期指導(dǎo)母細(xì)胞后期要轉(zhuǎn)錄的基因要轉(zhuǎn)錄的基因4.Delta-Notch Signaling control skin-nerve regulatory in the Insect CNSnIn all verteb

20、rate embryos, there is a stage when cells located along the dorsal ectoderm move toward internal regions of the embryo and form the neural tube.nCells located in the ventral most region of the neutral tube form floorplate, where the secreted signaling molecule Sonic Hedgehog(Shh) is expressed. Shh f

21、unctions as a gradient morphogen. by which Cells Are Instructed to Express Specific Sets of Genes during DevelopmentuExamples of the Three StrategiesuThe Molecular Biology of Drosophila Embryogenesispositional informationThe Molecular Biology of Drosophila EmbryogenesisOocyte n. 卵母細(xì)胞卵母細(xì)胞 metamorphos

22、is n.變形變形Larval adj.幼蟲的幼蟲的 Larva n.幼蟲幼蟲 pupa n.昆昆蛹蛹Molt n. 換毛期換毛期 Thorax n. 胸腔胸腔An Overview of Drosophila EmbryogenesisThe Molecular Biology of Drosophila EmbryogenesisOocyte n. 卵母細(xì)胞卵母細(xì)胞 metamorphosis n.變形變形Larval adj.幼蟲的幼蟲的 Larva n.幼蟲幼蟲 pupa n.昆昆蛹蛹Molt n. 換毛期換毛期 Thorax n. 胸腔胸腔A Morphogen Gradient C

23、ontrols Dorsal-Ventral Patterning of the Drosophila EmbryonAfter fertilization, Sptzle binds to the cell surface Toll receptor.Depending on the concentration of Sptzle, Toll is activated to greater or lesser extent.Peak activation of Toll is in ventral regions, where the Sptzle concentration is high

24、est.nToll signaling causes the degration of a cytoplasmic inhibitor Cactus, and the release of Dorsal from the cytoplasm into nuclei.nThe Dorsal gradient specifies three major thresholds of gene expression across the dorsal-ventral axis of embryos undergoing cellularization.twist generhomboid geneso

25、g genetwistSegmentation Is Initiated by Localized RNAs at the Anterior and Posterior Poles of the Unfertilized Eggbicoidoskar The Bicoid Gradient Regulates the Expression of Segmentation Genes in a Concentration-Dependent FashionnOnly high concentrations of Bicoid activate the expression of orthoden

26、ticle, while both high and intermediate concentrations are sufficient to activate hunchback.nThis differential regulation of orthodenticle and hunchback depends on the binding affinities of Biciod recognition. nThe Bicoid protein binds to DNA as a monomer, Bicoid monomers interact with each other to

27、 foster the cooperative occupancy of adjacent sites.Hunchback Expression Is also Regulated at the level of TranslationThis dual regulation of hunchback expression produces a steep Hunchback protein gradient with the highest concentrations located in the anterior half of the embryo and sharply diminishing levels in the posterior half.The Gradient of Hunchback Repressor Establishes Different Limits of Gap Gene ExpressionHunchback and Gap proteins produce Segmentation Stripes of Gene ExpressionWe will consider the expression of eve stripe 2 for exam