Apoptosis under physiological conditions and diseases

This presentation discusses the basic concept, mechanism and the functions of apoptosis

1. Apoptosis in health and disease Dr Ashok Kumar Professor, Department of Biochemistry AIIMS Bhopal

2. Apoptosis Types of cell death Characteristic Features of apoptosis Apoptosis in Physiological conditions Difference between Apoptosis & Necrosis Mechanism of apoptosis Initiators Effectors Regulators Apoptosis in Pathological conditions Apoptosis and cancer Apoptosis in neurodegenerative diseases Therapeutic approaches

3. Types of cell death Necrosis – non-apoptotic accidental cell death (common definition) <or> morphology seen after a cell has already died (pathology; has nothing to do with biochemistry of how the cell died) Autophagy – degradation of cellular components within dying cells in an autophagic vacuole; begins with sequestration of cytoplasmic material within phagosomes , Oncosis (Ischemic cell death) ; accompanied by cellular swelling, organelle swelling, blebbing , and increased membrane permeability; oncotic cells proceed to necrosis with lysis and spillage of contents before being recognized by phagocytosis; inflammation results Pyroptosis –Associated with anti-microbial response; induced by infection with Salmonella and Shigella ; inherently proinflammatory ; dependent on Caspase -1 Apoptosis…..

4. Fink et al Inf. Imm. Apr.2005: 1907-16

5. Features of Apoptosis An active programmed process of autonomous cellular dismantling that avoids eliciting inflammation Characterized by: - cytoplasm shrinkage - membrane blebbing - chromatin condensation - cleavage of DNA at internucleosome site - caspase mediated - exposure of phosphaotidylserine on cell surface - Formation of apoptotic bodies - corpse clearance via phagocytosis Fink et al Inf. Imm. Apr.2005: 1907-16

6. Final stage of Apoptosis Normal Leukocyte Apoptotic Leukocyte

7. Apoptosis in Physiological Conditions Development: CNS Development: Thyroid hormone Metamorphosis Regulation of cell number in tissues (homeostasis and tumorigenesis) Development of B and T cells via negative selection Tissue remodeling: Gut epithelium, Involution of mammary gland

8. APOPTOSIS: important in adults Tissue remodeling (eliminates cells no longer needed): Virgin mammary gland Late pregnancy, lactation Involution (non-pregnant, non-lactating) Apoptosis Apoptosis - Testosterone Prostate gland

9. Apoptosis is also important in the development of the nervous system

10. Localization of apoptotic cells in cortical layers at P8 stage a b c I II-III IV V VI

11. Photomicrographs of coronal sections of primary somatosensory cortex showing cleaved caspase-3 and neurofilament immunofluorescence labeling in the euthyroid (A–D) and hypothyroid (E–H) rat pup at P0. Kumar A et al. Endocrinology 2006;147:4893-4903 ©2006 by Endocrine Society

12. Apoptosis vs Necrosis

13. Apoptosis vs Necrosis

14. Apoptotic Pathway

15. Mitochondria-mediated pathway Inducing factors: Growth factor deprivation Stress Hypoxia DNA damage Oxidative stress Bcl-2 Bcl-x L Bax AIF SMAC Caspase-3 activation ROS

16. APOPTOSIS: control Intrinsic pathway (damage): Mitochondria Cytochrome c release Pro-caspase 9 cleavage Pro-execution caspase (3) cleavage Caspase (3) cleavage of cellular proteins, nuclease activation, etc. Death BAX BAK BOK BCL-Xs BAD BID B IK BIM NIP3 BNIP3 BCL-2 BCL-XL BCL-W MCL1 BFL1 DIVA NR-13 Several viral proteins

17. Cadiolipin Oxidation induces cytochrome c release

18. Identification of Apoptosis Annexin V Labeling

19. Identification of Apoptosis Caspase activation assays Caspase western blotting DNA Fragmentation

20. Severe hyperthyroidism-induces apoptosis in rat liver

21. Severe hyperthyroidism-induces apoptosis in rat liver

22. Altered mitochondrial morphology by T 3 In Vivo In Vitro

23. Regulators of apoptosis

24. Apoptosis in Pathological Conditions

25. Apoptosis and Cancer Bcl2: oncogene P53, PTEN, Rb : tumor suppressor

26. Apoptosis in Neurodegenerative Diseases Alzheimer’s Diseases Parkinson’s Disease Huntington Diseases

27. Therapeutics BH3 only poteins ( Bax ): mimics Caspase Inhibitors