Apoptosis (Programmed Cell Death)
Apoptosis, or programmed cell death, is a genetically regulated process that removes unwanted or damaged cells without provoking inflammation. It plays a fundamental role in embryonic development, immune system regulation, and tissue homeostasis. Dysregulation of apoptosis contributes to cancer, neurodegeneration, and autoimmune diseases (Kerr, Wyllie, & Currie, 1972). overview diagram of apoptosis Molecular Mechanisms of Apoptosis Intrinsic (Mitochondrial) Pathway The intrinsic pathway is triggered by intracellular stress signals such as DNA damage, oxidative stress, or growth factor withdrawal. These signals cause mitochondrial outer membrane permeabilization (MOMP), releasing cytochrome c into the cytosol. Cytochrome c associates with Apaf-1 and dATP to form the apoptosome, which activates initiator caspase-9 and the downstream effector caspases-3, ‑6, and ‑7 (Danial & Korsmeyer, 2004). Stress signals → MOMP Cytochrome c + Apaf-1 + dATP → apoptosome Caspase-9 ac...