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Cell proliferation and Diseases

Cell proliferation and Diseases. Cell proliferation a process of cell division and regeneration, which results in an increase in the cell number with exact passages of genetic information to their daughter cells. Cell cycle. An ordered series of events leading to replication of Cells

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Cell proliferation and Diseases

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  1. Cell proliferation and Diseases

  2. Cell proliferation a process of cell division and regeneration, which results in an increase in the cell number with exact passages of genetic information to their daughter cells.

  3. Cell cycle • An ordered series of events leading to replication of Cells • Four phases: G1→S→G2→M • Quiescent cells: under certain conditions, cells exit the cell cycle during G1 and remain in the G0 state as nongrowing and nondividing cells. • Appropriate stimulation of such cells induces them to return to G1 and resume growth and division.

  4. Regulation of the Cell Cycle 1.Cell cycle self-control 2.Regulation of the cell growth by extracellular signals

  5. Cell cycle self-control • /Basic control of Cell Cycle • Cyclins • Cyclin Dependent protein Kinases (CDK) ---Cell cycle dependent fluctuation of cyclin contents and CDK activities • CDK inhibitors (CKI) • RB-E2F pathway and G1/S transit control • Checkpoint of cell cycle

  6. cyclin CDK Regulatory subunit Cyclin box Cyclin -COOH H2N- CDK PSTAIRE Combine Catalytic subnuit Cyclin/CDK • (1) Cyclins • cyclical concentrations during the courses of cell cycle. • 16 cyclins have been identified: A,B1,B2,C,D1,D2,D3,E,F,G1,G2,H,I,K,T1,T2. • Common structure: cyclin box, a series of 100 amino acids, which is a domain used to bind and activate CDKs.

  7. Cyclin-CDK复合物及其相关蛋白 Cyclins 相关CDKs 细胞周期作用 相关蛋白 底物 降解 A CDK1，CDK2 S+G2, M p107+E2F，p21，PCNA Rb ubiquitin B(B1,B2) CDK1(cdc2) G2, M p21,PCNA Rb ubiquitin C CDK8 G1 - - PEST D(D1-3) CDK4(2,5,6) G1 Rb,p21,p27,p15,p16,PCNA Rb PEST E CDK2 G1+G1, S p107+E2F ,p21,PCNA Rb PEST F - S - - - G - G1 - - - H CDK7 G1,S,G2, M - CDK1,4,6 - Cyclin周期变化

  8. SUMO Degradation of cyclins :主要是通过泛素-蛋白酶体进行泛素化降解 1.CyclinA, B1, B2：N端降解盒(destruction box) ，通过泛素连接酶催化泛素与cyclin结合，被26S蛋白酶体水解。 2. CyclinD, E：也通过类似途径降解。N端无降解盒，C端PEST序列与其降解有关(proline, glutamic acid, serine, threonine)

  9. 泛素 蛋白质 降解的蛋白质 Ubiquitin Conjugation. The ubiquitin-activating enzyme E1 adenylates ubiquitin (Ub) and transfers the ubiquitin to one of its own cysteine residues. Ubiquitin is then transferred to a cysteine residue in the ubiquitin-conjugating enzyme E2. Finally, the ubiquitin-protein ligase E3 transfers the ubiquitin to a lysine residue on the target protein. • 26S proteasome digests the ubiquitinated proteins. • This ATP-driven multisubunit protease spares ubiquitin, which is then recycled. • The 26S proteasome is a complex of two components: a 20S proteasome, which contains the catalytic activity, and a 19S regulatory subunit.

  10. (2) Cyclin-dependent kinases (CDKs) • CDK 1-9: 一组丝氨酸/苏氨酸蛋白激酶 • Mechanism of CDK activation • Cyclin dependent (cyclin binding) • Phosphorylation dependent (some specific amino acid phosphorylation and dephosphorylation) • Each CDK can associate with different cyclins, and the associated cyclin determines which proteins are phosphorylated by the CDK-cyclin complex.

  11. ▲CDK2与cyclin E结合， CDK4、CDK6与cyclin D1、D2、D3结合 pRb磷酸化 游离E2F释放↑ 启动G1期 DNA合成 启动S期 CDK与不同cyclin结合活化调控细胞周期 ▲CDK2与cyclin E和A结合后 促进S期 ▲CDK1与cyclin A结合 启动G2期 ▲CDK1与cyclin B1结合(Maturation promoting factor,MPF) 启动M期

  12. 去磷酸化 Cyclin与CDK结合磷酸化 CDK活化 CAK对CDK的磷酸化 Cell cycle CDK结合Cyclin、磷酸化/去磷酸化→ CDK活化， 启动cell cycle CDK激酶（CDK activating kinase，CAK）

  13. M phase kinase regulates entry into mitosis • Also called maturation promoting factor, or M phase promoting factor (MPF) • 34 kD Cdc2 catalytic subunit； • associate with cyclin A or B • Activation requires modification of Cdc2 • Inactivation is achieved by physical destruction of cyclin (proteasome) • phosphate that is necessary at Thr-161 is added by CAK. • wee1 kinase phosphorylates Tyr-15 to maintain the M phase kinase in inactive form • Cdc25 phosphatase removes the phosphate from Tyr-15. Cdc25 is itself activated by phosphorylation; and M phase kinase can perform this phosphorylation, creating a positive feedback loop. • Separate kinases and phosphatases that act on Thr-14 have not been identified

  14. Phosphorylation State of CDK1 and the Activity of Mitosis Promoting Factor Wee1 CAK Cdc25 CDK1的激活需要Thr14和Tyr15去磷酸化和Tyr161的磷酸化 （磷酸酶P80cdc25）

  15. Control of Mitosis Requires CDK1 Phosphorylation and Dephosphorylation

  16. cell cycle↑ ▲ Cyclin/CDK、CAKCDK磷酸化激活 影响CDK活性因素 ▲ CDK抑制因子(CDI) cyclin/CDK CDK活性↓ cell cycle↓ ▲pRb、P53、c-myc、UPP、磷酸酶等参与对CDK的调控。

  17. (3) CDI/CKI: CDK inhibitors Two classes • INK4 (inhibitors of kinase 4) family ---specific for cdk4 and cdk6 ---four members: p16INK4A, p15INK4B, p18INK4C, and p19INK4D • The CIP (Cdk inhibitory protein) /KIP (kinase inhibiting protein) family ---inhibit all G1 and S phase cdk enzymes ---three members: p21Cip1/WAF1, p27Kip1, and p57Kip2

  18. CKIs and Cell Cycle Control

  19. (4) RB-E2F pathway: G1-S control RB • Tumor suppressor • Substrate for CDK-cyclin D • Bound to transcription factor E2F • nonphosphorylated form of RB forms a complex with cdk-cyclins. • phosphorylation causes RB to release E2F

  20. E2F-regulated genes • DNA polymerase a • Dihydrofolate reductase (DHFR) • Thymidine kinase • Thymidylate synthase • CDK1 (Cdc2) • PCNA • Cyclin E • E2F itself

  21. E2F-related transcription factors DP1, 2, or 3

  22. ■增殖信号（生长因子 ） EGF, PDGF, NGF, IGF, IL, etc ■抑制信号（TGF-β） 下调cyclin和CDK4的表达, 促进P21wafl、P27kipl和P15ink4b等CDI产生，使细胞阻滞在G1期。 pRb ■细胞生长条件不具备 使P16INK4a和P15INK4b增加， 并抑制Cyclin D-CDK4/6复合物的功能， 细胞阻滞G1期。 E2F 2. Regulation of the Cell Growth By Extracellular Signals and Pathways G1期“限定点”（restriction point）决定细胞是否进入周期。 “限定点”主要受细胞外信号的调控。

  23. TGF-抑制细胞周期进展的机制

  24. Possible interactions between MAPK pathways and the cell cycle

  25. 3. Checkpoint of Cell cycle • DNA integrity---DNA damage checkpoint: G1/S • unreplicated DNA: S/G2 • paired kinetochores---Spindle assembly checkpoint: G2/M • division—Maintenance of Cell ploidy

  26. P53 Protein • DNA损伤： integrating cellular responses to stress • ---细胞周期阻滞：磷酸化P53，上调 p21Cipl基因转录。P21Cipl能与多种 CDK-cyclin复合物结合，抑制CDKs激活，阻滞G1/S过渡；并直接结合抑制PCNA从而抑制DNA复制。为DNA修复提供时间。 • ---DNA修复: 激活DNA损伤修复相关基因 • ---细胞凋亡：激活Bax凋亡基因，下调Bcl-2抗凋亡基因表达，诱导凋亡。 • P53突变或缺失

  27. Regulation of p53 Increased half-life of p53 is the major mechanism for the increased protein level, although transcriptional or translational regulation may also contribute Alterations in p53 protein stability: feedback regulation by MDM2 Post-translation modification: phosphorylation and acetylation Changes in intracellular location p53 and MDM2

  28. Non-genotoxic stress heat, cold, hypoxia, low pH, heavy metals, kinase inhibitors B. Genotoxic Stress radiation, UV, DNA-damaging agents DNA, protein damage, receptor activation DNA-PK RAS/ MAPK PARP, ATM, NBS, BLS, FAS ?? Increase in p53 levels or activity Mdm2 Bax GADD45 p21 PCNA Bcl-2 Bcl-XL G2 Arrest CDKs MAP4 DNA replication Rb P Apoptosis E2F G1 Arrest Rb A. p53-regulated genes and interacting proteins Up-regulation: p21, gadd45, mdm2, Bax, Fas, CKM, CycG, TSP1, IGF-BP3, BTG2 Down-regulation: bcl-2, NOS2, IL-6, bFGF, c-fos, MDR1, b-myb, PCNA, DNApola, hsp70, MAP4, TOPIIa,VEGF Interacting proteins: RPA, Mdm2, MdmX, hsp72/hsc73, 53BP2, TBP, XPA, XPB, CSB, WT1, DP-1, RAD51/RecA, SV40 T, Adv E1B, HPV E6, HBX

  29. ATM (ataxia telangiectasia mutated)，ATR (ATM and Rad3-related)

  30. Cell proliferation dysregulation

  31. 细胞增殖分化异常与相关疾病 增殖异常 分化异常 增殖分化异常 再生障碍性贫血 肥胖症 恶性肿瘤 白癜风 遗传性血红蛋白病 银屑病 前列腺肥大 肌营养不良 畸胎瘤 动脉粥样硬化 先天畸形 家族性红细胞增多症 X-连锁-球蛋白缺乏症 高IgM血症 细胞增殖异常 • 细胞增殖↓ 分化不良（过度） → 组织器官发育不全 • 细胞增殖↑ 分化不全 （不足）→ 肿瘤发生 • 细胞过度增殖或不足:本质是细胞周期调控异常 • 细胞周期的驱动失控（Cyclin、CDK和CDI） • 监控（检查）机制受损(Checkpoint) • 信号调控异常(signaling)

  32. G1/S交界处失察 • ▲P53功能正常 细胞进入S期 • DNA损伤 修复成功 • G1/S交界处 细胞周期停顿G1期 对损伤DNA修复 • DNA修复失败 • 诱导细胞凋亡 下调bcl-2基因表达或激活bax 基因 P53 1.恶性肿瘤(细胞增殖异常机制) (1)细胞周期监控机制受损 DNA损伤导致基因突变、缺失、易位、染色体重排等 G1/S、G2/M检查点异常,探测DNA损伤功能降低 ▲P53突变或丢失 正常细胞 肿瘤细胞 致变剂 检测点检查功能↓ 遗传不稳定性 复制忠实性↓

  33. G2/M 交界处失察 • G2/M交界处 • DNA双链断裂 • ▲激活DNA损伤检查点 阻止细胞进入M期 • 诱导修复基因转录 • 完成断裂的DNA修复 • ▲失去G2/M检查点的阻滞作用 染色体发生重排、丢失

  34. 人类肿瘤p53基因突变热点和频率 肿瘤型 突变频率（%） 突变热点 肿瘤型 突变频率（%） 突变热点 肺癌 56 157，248，273 前列腺癌 30 不确定 结肠癌 50 175，245，248，273 肝细胞癌 45 249 食道癌 45 不确定 胶质癌 25 175、248 卵巢癌 44 273 乳腺癌 22 175、248、273 胰腺癌 44 273 子宫内膜癌 22 248 皮肤癌 44 248、278 甲状腺癌 13 248、273 胃癌 41 不确定 白血病 12 175、248 头颈鳞癌 37 248 宫颈癌 7 273 膀胱癌 34 280 软组织肉瘤 31 不确定 37

  35. 【Cyclin D 过表达致肿瘤机制】 Cyclin D过表达+生长因子 正常细胞 CDKs的瀑布效应↑ 肿瘤细胞 (2)细胞周期驱动机制失控 （1）Cyclins异常： 肿瘤发生与cyclin（D、E）过量表达有关 【Cyclin D1 （原癌基因）过表达原因】 ▲基因扩增： 是Cyclin D1过表达的主要机制，乳腺癌、胃癌、食道癌存在Cyclin D1基因扩增过度。 ▲染色体倒位 Cyclin D1基因倒位，于甲状旁腺启动子控制下，Cyclin D1蛋白合成↑，甲状旁腺腺癌。 ▲染色体易位 Cyclin D1基因t(11:14) (q13:q32)易位，受Ig重链基因增强子影响，Cyclin D1表达↑。 ▲ 基因突变 Cyclin D1的T286突变，Cyclin D1泛素化受阻，半衰期延长。

  36. （2）CDK的增多 主要CDK4、CDK6过表达。 CDK4↑+ cyclin D结合↑ CDK4/cyclin D↑ CDKs表达↑ pRb pRb磷酸化↑ 细胞增殖过度 E2F ↑ G1/S过渡加速

  37. （3）CDI表达不足和突变： 肿瘤细胞常出现CDI（肿瘤抑制基因）表达不足或突变 ▲ InK4失活 p16 InK4基因失活原因：突变或缺失、染色体易位、p16 InK4高度甲基化。 【Mechanism】 p16 InK4基因表达↓ 抑制CDK4与cyclin D结合↓ 细胞周期处在“易于”被启动状态 正常细胞肿瘤细胞 ▲ Kip/Cip减少 P21cip1正常功能cyclins/CDKs活性↓ 细胞周期速度↓ 抑制增殖细胞核抗原（PCNA） 阻滞DNA复制 【Mechanism】 P53基因突变 P21cip1转录↓ DNA受损的细胞增殖↑ 正常细胞肿瘤细胞

  38. Mutation of G1/S regulators in cancer Pink: loci with defined specific genetic or epigenetic alteration ; Yellow: alterations mechanism unkown; Aasterisk: Alterations relevant for tumor prognosis

  39. (3)Membrane-to-Nucleus Signaling Pathways Involved in CancerProteins in white letters on black fill have been implicated as oncoproteins or tumor suppressor proteins

  40. ■临床症状：以巨核细胞增殖为主的骨髓增生性疾病。伴有血■临床症状：以巨核细胞增殖为主的骨髓增生性疾病。伴有血 小板持续增多和血小板功能异常，有反复自发性 出血及血栓形成。 ■病因与机制：X染色体遗传、TGF-减少、辅助细胞缺乏等。 ■病因与机制：细胞凋亡出现下降，增殖不变，导致良性前列腺增生。 ■病因与机制：表皮生长因子受体的增加和受体的减少是引起 表皮细胞增长过快的原因。 2.原发性血小板增多症（PT） 3.良性前列腺增生 4.银屑病

  41. Therapeutic targets

  42. Cell Differentiation and Diseases

  43. 1.Basic Concepts of Cell Differentiation • Cell differentiation gives rise to different kinds of cells with the specialized morphology, metabolism, and physiological functions from the cells of the same origin • Transdifferentiation 转分化 • Dedifferentiation 去分化

  44. Inner Cell Mass • 干细胞(Stem cell): • 具有自我更新、 • 高度增殖、 • 多向分化的能力的原始细胞. • 干细胞类型: • Totipotent stem cell: 具有向机体各种细胞分化的潜能. • Pluripotent stem cell （embryonic stem cells): 可分化成除了胎盘外的任何一种细胞. • Multipotent stem cell: 能分化成特定功能的细胞, 如造血干细胞能够分化成血液和免疫系统中的各种细胞 • Committed stem cell

  45. 胚胎干细胞（Embryonic stem cells）： • 受精卵分裂发育成囊胚内层细胞团，具备分化成不同类型体细胞的“全能性”。来源于人工受精后早期发育胚胎，可离体培养，在特定条件下可分化特异功能细胞、形成组织、器官。 • 成体干细胞（Adult stem cell, Somatic stem cells）： • 成年动物体内的干细胞，具有一定的分化潜力，但分化方向比较固定。如造血干细胞，皮肤、小肠、肝、神经干细胞等。成体干细胞体外培养相对困难，只能从外周血、骨髓、脂肪中搜集。如造血干细胞治疗器官移植后的免疫修复等的干细胞疗法。 • 诱导性多能干细胞（induced pluripotent stem cells, iPS cells）： 通过细胞内部重编程，突破成体干细胞分化能力限制，使其具备胚胎干细胞类似的发育多潜能性。用于替代胚胎干细胞应用。 • 2007年，美国和日本科学家利用病毒载体转入四个转录因子（Oct4, Sox2, Klf4 和c-Myc），将人皮肤细胞转化为类似于胚胎干细胞。 • 已在多种动物和人体细胞中诱导获得iPS细胞；可利用iPS技术将人皮肤细胞转化为肝细胞等；诱导技术革新。 • 2009年，中国科学家利用iPS细胞通过四倍体囊胚注射，得到发育存活并有繁殖能力的小鼠，证明iPS细胞拥有类似胚胎干细胞的全能性，“为克隆成年哺乳动物开辟了一条全新道路”。 • 应用： • 干细胞治疗和再生医学细胞来源，实现器官修复、组织再生。 • 制药行业，干细胞作为新药筛选的模型，进行毒理、药效试验。 • 研究干细胞增殖以及分化调控，理解癌症发生的分子机制，发现新的治疗靶点。 • 发育生物学领域。

  46. 2．Mechanism of cell differentiation （1）细胞决定（Determination）的选择作用 是指细胞内某些基因永久地关闭，而另一些基因按时空表达，使细胞向某一特定方向分化。“决定”先于分化。 （2）细胞质在决定细胞差别中作用 由于干细胞在分裂时，细胞质分配的不均匀，导致子代干细胞的胞质组分（细胞质决定子）不同，导致子细胞产生差别。 （3）细胞间相互作用 细胞分化与细胞所在位置及与其他细胞的联系有关。其效应可以是细胞间直接接触所进行信息转导、以及细胞外物质的作用。 （4）细胞微环境

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