Mitochondria-mediated apoptotic pathway

The **mitochondria-mediated apoptotic pathway** (also called the intrinsic or mitochondrial pathway of apoptosis) is a fundamental **cell death signaling pathway** that is activated in response to intracellular stressors such as DNA damage, hypoxia, oxidative stress, and deprivation of growth factors[1][2][7]. It involves a series of tightly regulated molecular events leading to mitochondrial outer membrane permeabilization (MOMP), primarily controlled by the balance between pro-apoptotic (BAX, BAK) and anti-apoptotic (Bcl-2, Bcl-XL) **Bcl-2 family proteins**[1][3][4][5]. Upon MOMP, mitochondria release apoptogenic factors including **cytochrome c**, which binds Apaf-1 and ATP/dATP to form the **apoptosome**, leading to activation of initiator caspase-9, and subsequently executioner caspases (e.g., caspase-3 and -7)[1][2][5][6]. Additional factors released include SMAC/DIABLO and OMI/HtrA2, which antagonize inhibitors of apoptosis (IAPs)[6]. Dysregulation of this pathway is central to the pathogenesis of cancers (where it is frequently inhibited), neurodegenerative diseases, and other forms of tissue injury[2][4][5]. The pathway itself is a **signaling mechanism**, not a discrete molecule or receptor, and thus is not a therapeutic target in the sense of being an individual protein or receptor; rather, specific molecular components of the pathway (e.g., BCL-2, BAX) are therapeutic targets[1][3][5][7]. The term "mitochondria-mediated apoptotic pathway" refers to a process, not a single gene or protein, and should not be treated as a canonical therapeutic target or biomolecule. For structured target annotation purposes, one should instead reference specific components (such as "B-cell lymphoma 2" or "BAX protein").

Other names

Intrinsic apoptotic pathwayIntrinsic pathway of apoptosisMitochondrial apoptosis pathway

Induction of mitochondrial outer membrane permeabilization (MOMP); Inhibition of anti-apoptotic Bcl-2 proteins to trigger cytochrome c release and caspase activation