Cellular apoptosis pathway (None)

The cellular apoptosis pathway represents a highly regulated form of programmed cell death characterized by distinct morphological and biochemical changes including cell shrinkage, chromatin condensation, DNA fragmentation, and formation of apoptotic bodies[3]. The pathway operates through two main routes: the intrinsic (mitochondrial) pathway, initiated by intracellular stress signals such as DNA damage or growth factor deprivation[1][4], and the extrinsic pathway, triggered by external signals through death receptors like Fas and TNF receptors[3]. Both pathways converge on the activation of executioner caspases (particularly caspase-3, -6, and -7), which systematically degrade cellular components[5]. The intrinsic pathway involves the Bcl-2 family proteins that regulate mitochondrial outer membrane permeabilization, leading to cytochrome c release and apoptosome formation with Apaf-1 and procaspase-9[1]. The extrinsic pathway forms the death-inducing signaling complex (DISC) containing FADD and caspase-8[3]. A critical feature distinguishing apoptosis from necrosis is the externalization of phosphatidylserine on the cell surface, enabling recognition and phagocytic removal of apoptotic cells without inflammatory response[2][5]. In healthy adults, approximately 50 to 70 billion cells undergo apoptosis daily, playing essential roles in development, tissue homeostasis, and immunity[3]. Dysregulation of this pathway contributes to various diseases, with excessive apoptosis causing atrophy and insufficient apoptosis enabling cancer development[3].

Other names

Programmed cell death pathwayApoptotic pathwayApoptosis signaling pathway

Bcl-2 family modulation (promoting or inhibiting mitochondrial outer membrane permeabilization), Death receptor activation (extrinsic pathway initiation), Caspase activation or inhibition, IAP protein inhibition, p53 pathway activation