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17 Cards in this Set
- Front
- Back
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What are the initiator pathways for apoptosis? Common?
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a. Intrinsic: P53 and Bcl pathways
b. Extrinsic: Fas/FasL c. Common: Caspase |
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Describe how apoptosis as a physiological process
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a) Involution of structures during development
b) Elimination of immune cells i) E.g., self-reactive lymphocytes ii) E.g., neutrophils in inflammatory process c) Involution following hormonal withdrawal i) E.g., menstruation: shedding of endometrium d) Cytotoxic T-cell mediated elimination of infected cells or neoplastic cells |
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Describe apoptosis as pathologic process
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a) “Insults:” radiation; drugs; DNA damage
b) Viral infections i) E.g., Councilman (acidophil) body: apoptotic hepatocyte in viral hepatitis c) Autoimmunity d) Neoplastic cells |
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Describe the two major pathways of apoptosis, please briefly list examples
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a) Intrinsic: injury, radiation, toxins, ROS, withdrawal of growth factors
b) Extrinisc: death receptors, cytotoxic T-cell meditated |
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What is the common execution pathway for apoptosis?
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a) Caspase enzyme cascade
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From the Bcl family, what are 2 pro apoptotic regulators?
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a) Bax, Bak
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From the Bcl family, what are 2 anti-apoptotic regulators?
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a) Bcl-2, bcl-x
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What are the 2 major players in the intrinsic apoptotic pathway?
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a) Injury (toxins, radiation, DNA damage)
b) Withdrawal of growth factors |
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Discuss the intrinsic pathway of intrinsic apoptosis
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a) increase¬ p53 tumor suppressor gene product
i) Arrests cell in G1 to repair DNA ii) If unsuccessful repair -->apoptosis iii) increased¬ Pro-apoptotic members of Bcl family of proteins: Bax, Bak |
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Discuss what happens with a withdrawal of growth factors (with respect to apoptosis)
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a) Alter balance in Bcl family to favor apoptosis
i) increase¬ Bax, Bak; decrease bcl-2, bcl-x |
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Increased activity of Bax/Bak promotes what?
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a) Apoptosis
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Increased activity of bcl-2 and bcl-x promote what?
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a) Anti-apoptosis
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What are the 2 major players in the extrinsic pathway of apoptosis?
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a) Death receptors/Ligands
b) Cytotoxic T-cell mediated cell death: granzyme B (Granzyme-B induces apoptosis through Caspase-dependent and Caspase-independent mechanisms-- it cleaves after aspartic acid residues and thus activates Caspase-mediated apoptosis) |
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What are 4 examples of death receptors/ligands?
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a) Fas/FasL
b) TNFR1/TNF c) E.g. elimination of self-recognizing lymphs |
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Provide clinical examples for both physiologic and pathologic apoptosis
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a) Pathologic: insults, radiation, drugs, viral infections (councilman bodies)
b) Physiological: self reactive lymphocytes, involution of structures during development, etc |
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What can happen when you have too little apoptotic activity (2 examples) i) Failure to eliminate self-reacting lymphocytes
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a) Cancers
i) Neoplastic cells proliferate despite DNA damage b) Autoimmunity |
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What can happen with too much apoptotic activity (3 examples)
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a) Neurodegenerative disorders (e.g., Parkinson disease)
b) Ischemic injury c) Death of virally infected cells |
