Cell death

When cells undergo irreversible injury they can progress to cell death.

Two types: apoptosis and necrosis.

Necrosis occurs when cell membranes are injured and lysosomal enzymes to enter the cytoplasm and digest the cell.

Apoptosis characterized by nuclear dissolution without complete loss of membrane integrity.

The death-receptor pathway is activated when tumor necrosis factor super family members bind to cell surface death receptors, members of the TNF receptor family.

Ligation of the TNF receptors initiates formation of a multi-protein death inducing signal complex.

Aggregation of the multi-protein death inducing signaling complex causes changes in its components that trigger catalytic activity of caspase 8, which is a central mediator of a apoptosis.

The BCL2 family controls the mitochondrial apoptotic pathway. Cell death-caspase 9 regulates the mitochondrial apoptotic pathway.

When intracellular sensors indicate the presence of overwhelming cell damage caspase 9 is initiated.

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