细胞凋亡与肿瘤

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（by Thonberry, 1997)
PROPOSED CASPAPSE FUNCTIONS AND STRUCTURE
How caspases dissemble a cell by cleaving a discrete set of proteins, using a variety of strategies.
坏死
NECROSIS
1858, Virchow A pathological type of cell death observed following physical or chemical injury , exposure to toxins, or ischemia (lack of oxygen). It is characterized by swelling, rupture of plasma membrane and cellular organelles, and release of cellular content into the surrounding tissue, leading in vivo to inflammation.
Caspases are regulated by opposing effects of activators and inhibitors in three pathways involving cofactors, initiator caspases and inhibitors.
线粒体的作用
Member
Caspase-1,-4,-5 Caspase-2,-3,-7 Caspase-6,-8, -9
Classification
I II III
Function
inflammation apoptosis apoptosis
Substrate Specificity
WEHD-X DEXD-X (I/L/V)EXD-X
DIFFERENCE BETWEEN APOPTOSIS AND NECROSIS IN BIOCHEMICAL FEATURES
APOPTOSIS
DNA Protein Substrate cleavage in nucleosome Caspases activated specific degrading
Bcl-2 rarely
no release, inflammation
检测方法
APOPTOSIS DETECTION
• • • • • MORPHOLOGICAL METHOD(LM, EM) DNA LADDER FLOW CYTOMETRY ANNEXIN V （for early APO) ISEL（in-situ end-labeling):TUNEL
程序化细胞死亡 PCD(programmed cell death)
1951，Glucksman Type of cell death in which a cell, in response to specific physiological or developmental signals, undergoes a regulated series of events that will lead to its death and removal from the organism.
半胱天冬氨酸蛋白酶 家族
CASPASE FAMILY
• • Cysteinyl Aspartate-specific Proteinases Pro-enzyme (prodomain, 20kD subunit, 10kD subunit) Substrates:>40
•
Caspase family
DD:death domaim DED: death effector domain FADD: Fas-associated death domain initiator: Caspase 8 (self-cleavage) effectors: Caspase 3
Pro-apoptotic and anti-apoptotic signaling by TNFR1( in macrophages and lymphocytes) and DR3 (in immune tissues)
TRADD: TNFR-associated DD TRAF2:TNFR-associated factor2 IκB/NF- κ B:signal
Apoptosis signaling by DR4 and DR5 and its modulation by decoy receptors (DcR)in tumor cell lines
DIFFERENCES BETWEEN APOPTOSIS AND NECROSIS IN MORPHOLOGICAL FEATURES
APOPTOSIS
NECROSIS
Volume shrinking, rarely lysing swelling Membrane blebbing rupture Organelles intact damaged Nucleus condensing, degrading lysing Lysosome intact lysing Mitochondria shrinking, Cyt.C-releasing swelling ______________________________________________________
细胞凋亡和肿瘤
细胞凋亡和肿瘤
APOPTOSIS AND TUMOR
定义 特征 分子机制 和肿瘤的关系
APOPTOSIS
Initially used to describe a subset of programmed cell deaths sharing a particular set of morphological features, which include membrane blebbing, shrinkage of cytoplasm, chromatin condensation, and formation of a DNA ladder. Sometimes used to refer to PCD of all types.(1972,Kerr, Wyllie & Currie)
Bcl-2
• • • • Inhibitors of apoptosis B cell lymphoma 2, 1984 Tsujimoto 229 aa, transmembrane Nuclear-core complex, Ca
2+
• Bax, Bax/Bcl-2 ratio • Bcl-x (Bcl-xL, Bcl-xS)
MITOCHONDRIA AND APOPTOSIS
---the role of mitochondria in cells
Fra Baidu bibliotek
Model for caspase activation by mitochondria. Multiple stimuli can trigger mitochondria to release caspase-activating proteins (cyto c, AIF and intramitochondrial caspases). Two mechanisms for release of caspase-activating proteins from mitochondria. Cyto c activates caspases by binding to Apaf-1, inducing it to associate with procaspase-9, thereby triggering caspase-9 activation and initiating the proteolytic cascade that culminates in apoptosis. Cells in which mitochondria have ruptured are at risk for death through a slower nonapoptotic mechanism resembling necrosis because of loss of the electrochemical gradient across the inner membrane
A: CAD/ICAD (caspase-activated deoxyribonuclease) B: lamina proteins C: regulatory and catalytic proteins (P152-4, in detail)
Caspase cascade in apoptotic cells. Effectors are activated by different initiators, each of which is activated by set of proapoptotic signals.
APO发生机制
How?
DEATH RECEPTORS AND OTHER SIGNALS
-----TELL CELLS WHEN TO DIE
BY ACTIVATION CASPASES (CD95, TNFR1, DR3, DR4/5)
APOPTOSIS SIGNALING BY CD95 (in activated T cells and NK cells and in other immune-privileged sites).
Apo2L in many tissues
APOPTOSIS REGULATORS
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ACTIVATORS INHIBITORS ---------------------------------------------------------------------Ced-3, Ced-4 Ced-9 Caspases, Apaf-1 Bcl-2 ---------------------------------------------------------------------Apaf-1:APO activating factor1 袁钧英，1993，Ced-3
The mitochondrial permeability transition(MPT). A speculative model showing some of the components of the permeability transition pore. The roles of porin and the benzodiazepine receptor remain circumstantial. In the open configuration, water and solutes enter the matrix, causing matrix swelling and outer membrane disruption, leading to release of cyto c and other proteins.
NECROSIS
non-specific cleavage non-specific degrading non-specific degrading
Inhibitor
ATP Reaction
Bcl-2, Caspases inhibitors
needed removal, no inflammation