考研資料：北京大學細胞生物學第十三章細胞凋亡與衰老ppt課件

1、Chapter 13Cell apoptosis Extracellular cotrol of cell division, cell growth, and apoptosisMitogens stimulate G1-Cdk and G1/S-Cdk activitiesPRIZED Horvitz, and Sulston share Physiology or Medicine Nobel 2019 “for their discoveries concerning genetic regulation of organ development and programmed cell

2、 death1090 131= 959(cells)機體構造機體構造細胞增殖細胞增殖細胞分化細胞分化細胞凋亡細胞凋亡細胞信號轉導細胞信號轉導染色體染色體DNADNA與蛋白質的相互作用與蛋白質的相互作用衰老衰老A simplified model of one way that mitogens stimulate cell divisionHuman cells have a built-in limitation on the number of times they can divideThe cell division is cotrolled not only by extracell

3、ular mitogens but also by intracellular mechanisms that can limit cell proliferation.Cell-cycle arrest or apoptosis induced by excessive stimulation of mitogenic pathways.Extracellular growth factors stimulate cell growthActivation of cell-surface receptors Activation of PI 3-kinaseActivation of elF

4、4E (translation initiation factor) and S6 kinase(phosphorylates ribosomal protein S6)Increasing protein synthesis and cell growth2.Apoptosis, Programmed cell death Biological functions of apoptosis In development, homeostasis, tumor surveillance, and the function of the immune system.細胞凋亡是多細胞生物在發(fā)育過程

5、中，一種由基因控制的自動的細胞生理性自殺行為。 Morphological and biochemical characteristics of apoptosis Morphologi changes: Early : Chromosome condensation, cell body shrink Later : Blebbing and Nucleus and cytoplasm fragment Apoptotic bodies At last: PhagocytosedA、Normal cell B、Apoptosis: Apoptotic bodies Biochemical c

6、haracteristics of apoptosis :Apoptosis induced by Cyto CLane 10 h 21 h 32 h 43 h 54 h 6Control 7Marker 2.0kbp1.00.50.2180200bp DNA ladder, Accumulation of tTG, PS flip-flop Contrast ofApoptosis and necrosisApoptosisNecrosisDeath by apoptosis is a neat, orderly process3.Molecular mechanisms of apopto

7、sis Early researches (MIT: Robert Horrid , 1986)C. elegans:1090 cells, The Finding of CED3 mutantWithout losing any of theircells to apoptosis.CED3 gene play a crucial role in the process of apoptosis.C elegans: a millimeter long, transparent body only a few cell types, from zygote to mature adult o

8、nly in 3.5days.131 cells death.線蟲體細胞凋亡研討：線蟲體細胞凋亡研討：PCD相關基因相關基因15個，分為四組：個，分為四組：1、與、與PCD有關的基因，擔任有關的基因，擔任PCD控制：控制：ced-3、ced-4和和ced-9。2、與、與PCD過程吞噬作用有關：過程吞噬作用有關：ced-1、ced-2、ced-5-8 和和 ced-10。3、核酸酶基因、核酸酶基因nuc-1, 控制控制DNA降解，但非降解，但非PCD所所必需。必需。4、影響特異細胞類型、影響特異細胞類型PCD的基因：的基因：ces-1、ces-2、cgl-1、和和 her-1. 保守性高，在哺乳

9、動物中有相應同源物：保守性高，在哺乳動物中有相應同源物： Ced-3=ICE, Ced-4=Apaf-1, Ced-9=Bcl-2.Mammalian: CED3 is related to mammalian interleukin- 1converting enzyme (ICE or caspase-1) Apoptosis is carried out by a proteolytic system caspase (1) Why called caspase?Active site: CysteineCleavage site: Asparatic acid Cysteine Asp

10、aratic acid specific proteaseAps-Xxx天冬氨酸特異性的半光氨酸蛋白水解酶Apoptosis can be divided into two phases：Activation phase： The cell responds to “death signals that commit it to undergoing self-destruction.Execution phase： The death sentence is carried out. Apoptosis cells are recognized by phagocytes because t

11、hey carry exposed markers, called “eat me signals. The best studied “eat me signal is the presence of phosphatidylserine molecules in the outer leaflet of PM of apoptotic cells (by flop-flipase). How to activate caspases?All caspases expressed as proenzymes ProcaspasesProcaspaseNH2-terminal prodomai

12、n: Highly variableLarge subunit (20kD)Small subunit (10kD)How are procaspases activated to initiate the caspase cascade?The activation is triggered by adaptor proteins that bring multiple copies of specific procaspases. 3 groups of caspase:1、apoptotic initiators: caspase-2, caspase-8, caspase-9 and

13、caspase-10 2、apoptotic executioners: caspase-3, caspase-6 ，caspase-7 and 14 (morphology change) 3、inflammatory mediateors: caspase-1, and caspase-11 Procaspases are activated by binding to adaptor proteinsThe caspase cascade involved in apoptosisProcaspase activation by proteolytic cleavage.Caspase

14、cascade The target proteins of caspase are the following: More than a dozen protein kinase, including FAK, PKC, and Raf1. FAK disrupt cell adhesion for the apoptotic cell.Lamins. Cleavage of lamins leads to the disassembly of the nuclear lamina and shrinkage of the nucleus.Proteins required for cell

15、 structure. Such as IF, actin, and gelsilin. Cleavage and inactivation of these proteins lead to changes in cell shape. Induce cell display signals marked it for phagocytosis .The inhibitor of CAD (Caspase-activated Dnase, an endonuclease). Cleavage of CAD inhibitor lead to activation of CAD, once a

16、ctivated, CAD translocates from the cytosol to the nucleus severing DNA into fragments.Enzymes involved in DNA repair. Which are inactivated by caspase cleavage. DNA repair is a homeostatic activity that is inappropriate in an apoptotic cell. Molecular pathways of apoptosisTwo principle pathways Ext

17、rinsic pathwayIntrinsic pathway(1) Extrinsic pathway: Fas Signaling PathwayFas (also called Apo-1 or CD95) is a member of the tumor necrosis factor receptor (TNFR) superfamily. Receptor-mediated pathway of apoptosisBcl-2 Family(cytoplasmic factors): Bad,Bid,and bax: promote apoptosis; Bcl-X, Bcl-w,and Bcl-2: prevent apoptosis.Internal stimuli: DNA damage, high Ca2+ , Oxidative stress(2) Intrinsic pathway: Mitochondrial pathwayThe mitochondria-mediated pathway of apoptosisVarious types ofcellular stressBcl-2 family: Bad or Bax to beco