Are caspases activated by phosphorylation?
The activation of various proteins is regulated by phosphorylation and dephosphorylation, both upstream and downstream of caspase activation. Many kinases/phosphatases are involved in the control of cell survival and death, including the mitogen-activated protein kinase signal transduction pathways.
What are the initiator caspases?
Caspase-8, caspase-10 and caspase-9 are believed to be the initiator caspases at the top of the caspase signaling cascade. Recruitment of caspases to DISC and apoptosome leads to their activation by dimer formation.
How are initiator caspases activated?
All caspases are synthesized in cells as catalytically inactive zymogens, and must undergo an activation process. The activation of an effector caspase, such as caspase-3 or -7, is performed by an initiator caspase, such as caspase-9, through an internal cleavage to separate the large and small subunits.
Are caspases secreted?
Inflammatory protease, caspase-1, is secreted from monocytes in a stably active form in response to inflammasome activation (INM3P. 441)
What do initiator caspases do?
Initiator caspases initiate the apoptosis signal while the executioner caspases carry out the mass proteolysis that leads to apoptosis. Initially synthesized as inactive pro-caspases, caspases become rapidly cleaved and activated in response to granzyme B, death receptors, and apoptosome stimuli.
Are caspases kinases?
Accumulating evidence suggests that cell death pathways are finely tuned by multiple signaling events, including direct phosphorylation of caspases, whereas kinases are often substrates of active caspases.
What is the activation of an effector caspase?
The activation of an effector caspase, such as caspase-3 or -7, is performed by an initiator caspase, such as caspase-9, through an internal cleavage to separate the large and small subunits.
How are caspases synthesized in cells?
All caspases are synthesized in cells as catalytically inactive zymogens, and must undergo an activation process. The activation of an effector caspase, such as caspase-3 or -7, is performed by an initiator caspase, such as caspase-9, through an internal cleavage to separate the large and small subunits.
What is the role of caspases in cell death?
Activation of caspases ensures that the cellular components are degraded in a controlled manner, carrying out cell death with minimal effect on surrounding tissues. Caspases have other identified roles in programmed cell death such as pyroptosis and necroptosis.
How are pro-caspases activated?
Activation involves dimerization and often oligomerisation of pro-caspases, followed by cleavage into a small subunit and large subunit. The large and small subunit associate with each other to form an active heterodimer caspase.