Apoptosis the programmed cell death

Hi brainy folks, Apoptosis is programmed cell death. It is natural process required for growth as well as maintenance of healthy state. It is mostly physiological where elimination of unwanted, old or self-reactive cell happens. Apoptosis requires ATP and the absence of inflammation is very characteristic feature differentiating it from Necrosis.

Apoptosis means “falling off” in Greek. For morphological features and difference between Apoptosis and Necrosis read here 👇 https://creativemeddoses.com/topics-list/necrosis-vs-apoptosis-six-major-differences/ .

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Biochemical features of Apoptosis

Protein cleavage

Caspases induces apoptosis by cleaving cellular protein, it breaks nuclear scaffold and cytoskeleton.

DNA Breakdown

Caspases activates endonucleases which breaks DNA into fragments. These DNA fragments makes DNA laddering pattern on agar gel electrophoresis.

Phagocytic Recognition

Early recognition of apoptotic cells by macrophages is facilitated by expression of phosphatidylserine and thrombospondin. Early recognition leads to rapid clearance of apoptotic bodies by phagocytes, hence there is no residual cell content to induce inflammation.

Causes of Apoptosis

Physiological

1. After serving the purpose -Neutrophils and lymphocytes undergo apoptosis after acute inflammatory reaction ends.These cells undergo apoptosis because they are deprived of necessary survival signals.
2. Self-destructive cells such as self-reactive lymphocytes die due to programmed cell death because they are potentially harmful and can induce autoimmune illnesses.
3. Embryogenesis-Implantation, organogenesis, developmental involution and metamorphosis processes of embryo development causes programmed destruction of unwanted cell.
4. Odd cells- Virus infected cells, cancer cells, and cells of transplanted organs.
5. Old cells in highly proliferating organs-Cell deletion in intestinal crypt epithelia, in order to maintain constant number.
6. Hormone-Dependent Involution-Endometrial cell breakdown during the menstrual cycle, ovarian follicular atresia in menopause, prostatic atrophy after castration and regression of the lactating breast after weaning.

Pathological

1. Atrophy after Duct Obstruction-Pancreas, parotid gland and kidney get gradual atrophy after duct obstruction.
2. Cell injury-Viral hepatitis, radiation, anticancer drugs and endoplasmic reticulum stress because of unfolded proteins.
3. Cancer cell death- in rapidly growing tumors.
4. Increased Mitochondrial Permeability-Injury and toxin induced mitochondrial permeability plays very important role in apoptosis.

Stay tuned for more on cell death and adaptation…

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Further reading 👇https://jeccr.biomedcentral.com/articles/10.1186/1756-9966-30-87

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