Table 1.

Apoptosis-regulatory and vital functions of caspases

Caspase	Knockout phenotype	Role in apoptosis	Other roles
Caspase-1	Mice develop normally	Role in ‘pyroptosis’, i.e. cell death initiated by activation of the inflammasome	Proteolytic maturation of interleukins, in particular IL-1β and IL-18
Caspase-2	Mice have excess oocytes Premature aging	Initiator/executioner caspase Initiator of apoptosis after DNA damage and during mitotic catastrophe	DNA repair
Caspase-3	Perinatal lethality Brain hyperplasia	Executioner caspase	B cell proliferation Differentiation of erythroblasts, monocytes, keratinocytes, and epithelial, sperm, skeletal, muscle, osteoblast and trophoblast cells Platelet maturation
Caspase-6	Mice develop normally	Executioner caspase	Unknown
Caspase-7	Perinatal lethality	Executioner caspase	Unknown
Caspase-8	Embryonic lethality Impaired heart development and decreased pool of hematopoietic precursors In humans, familial mutation leads to immunodeficiency	Initiator caspase of the death receptor (extrinsic) apoptotic pathway Proteolytically activates downstream caspases and Bid	Cell cycle control Macrophagic differentiation NF-κB-mediated pro-survival pathways Placental trophoblast differentiation T-cell proliferation
Caspase-9	Perinatal lethality Excess brain tissue	Initiator caspase of the mitochondrial (intrinsic) apoptotic pathway	In most differentiation processes in which caspase-3 has been implicated
Caspase-10	In humans, a familial mutation is linked with type II autoimmune lymphoproliferative syndrome	Putative initiator caspase of the extrinsic pathway Proteolytically activates downstream caspases and Bid	Implicated in the activation of NF-κB- mediated pro-survival pathways
Caspase-11	Mice develop normally Lymphocytes have a defect in actin depolymerization	Involved in neuronal cell death induced by MPTP and other pathological stimuli	IL-1 production Interacts with Aip1 and promotes cofilin-mediated actin depolymerization
Caspase-12	Mice develop normally	Initiator caspase in ER stress-dependent apoptosis	Attenuates inflammation Innate immune response
Caspase-14	Mice skin exhibit reduced hydration levels and enhanced sensitivity to UVB-induced apoptosis	Unknown	Terminal differentiation of keratinocytes

Abbreviations: Aip1, actin interacting protein 1; ER, endoplasmic reticulum; IL, interleukin; MPTP, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; UV, ultraviolet.