Intrinsic mitochondrial apoptosis pathway (IMAP)

The intrinsic mitochondrial apoptosis machinery is a highly regulated signaling network that governs programmed cell death in response to internal cellular stress, such as DNA damage or oxidative stress. This pathway is primarily controlled by the B-cell lymphoma 2 (BCL-2) family of proteins, which maintain a delicate balance between pro-survival and pro-apoptotic signals at the mitochondrial membrane. When the balance shifts toward pro-apoptotic signals, Mitochondrial Outer Membrane Permeabilization (MOMP) occurs, releasing cytochrome c and initiating the caspase cascade that leads to cell dismantling. In many cancers, this machinery is suppressed through the overexpression of anti-apoptotic proteins like BCL-2 or MCL-1, allowing malignant cells to evade death and develop resistance to chemotherapy. Therapeutic intervention focuses on using BH3 mimetics to neutralize these pro-survival proteins, thereby restoring the cell's natural ability to undergo apoptosis. This approach has proven particularly effective in hematologic malignancies, where drugs like Venetoclax have revolutionized the treatment landscape by directly inducing apoptosis in leukemia and lymphoma cells.

Other names

Mitochondrial apoptosis machineryIntrinsic apoptotic pathwayBcl-2 regulated apoptosis pathwayMitochondrial-mediated apoptosis

Drugs targeting this machinery primarily act as BH3 mimetics that bind to and inhibit pro-survival BCL-2 family proteins (e.g., BCL-2, BCL-XL, MCL-1). This inhibition releases pro-apoptotic proteins like BAX and BAK, which then oligomerize to cause Mitochondrial Outer Membrane Permeabilization (MOMP). MOMP leads to the release of cytochrome c into the cytosol, triggering the formation of the apoptosome and subsequent activation of the caspase cascade (Caspase-9, -3, and -7) to execute cell death.