How does caspase-3 get activated?

Caspase-3 is a cysteine–aspartic acid protease that cleaves cellular targets and executes cell death. Our current understanding is caspase-3 is activated by the cleavage of the interdomain linker and then subsequent cleavage of the N-terminal prodomain.

How does caspase-3 trigger apoptosis?

Caspase-3 is known as an executioner caspase in apoptosis because of its role in coordinating the destruction of cellular structures such as DNA fragmentation or degradation of cytoskeletal proteins (1). The activity of caspase-3 is tightly regulated and it is produced as zymogen in an inactive pro-form (1).

How is a caspase 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.

Is caspase-3 Required for apoptosis?

Caspase-3 is also required for some typical hallmarks of apoptosis, and is indispensable for apoptotic chromatin condensation and DNA fragmentation in all cell types examined.

How does caspase-9 activate caspase-3?

Caspase 3 appears to amplify caspase 8 and caspase 9 initiation signals into full-fledged commitment to disassembly. Caspase 8 and caspase 9 activate caspase 3 by proteolytic cleavage and caspase 3 then cleaves vital cellular proteins or other caspases.

How does caspase-3 assay work?

The Caspase-3 assay protocol is based on the formation of the chromophore p-nitroaniline (p-NA) by cleavage from the labeled substrate DEVD-pNA. The p-NA can be quantified using a spectrophotometer or a microtiter plate reader reading absorbance at 400 or 405 nm.

Which caspase is activated first?

The apoptosome recruits and activates the initiator caspase, caspase-9. Active caspase-9 then directly cleaves and activates effector caspases, such as caspase-3.

How do you activate apoptosis?

Apoptosis, a process important for clearing damaged or infected cells, is the induction of cell suicide and can be triggered by either intrinsic cues or activation of the relevant pathways by external ligands. One pathway of extrinsic signaling occurs through Apo2L/TRAIL which activates death receptors (DR) 4 and 5.

How does caspase-8 activate caspase-3?

In the context of extrinsic apoptosis, caspase-8 is activated by dimerization inside a death receptor complex, cleaved by auto-proteolysis and subsequently released into the cytosol. This fully processed form of caspase-8 is thought to cleave its substrates BID and caspase-3.

What does caspase-3 indicate?

Caspases are crucial mediators of programmed cell death (apoptosis). Among them, caspase-3 is a frequently activated death protease, catalyzing the specific cleavage of many key cellular proteins.

What is a limitation of the caspase-3 assay?

Additionally, the main limitations for our multiplexing protocol are that caspase-3/7 activity can determined but not quantified, and the resulting lysate cannot be used for downstream assays (i.e. Western blots or gene expression).

Is caspase-12 processed downstream of Apaf-1 and caspases-3?

We also demonstrated that caspase-12 was processed downstream of Apaf-1 and caspase-3, and neither overexpression nor knockdown of caspase-12 affected susceptibility of the cells to ER stress-induced cell death.

Is caspase-12 involved in ER stress-induced cell death?

Under ER stress conditions, BAX translocated to mitochondria and cytochrome c was released from mitochondria. We also demonstrated that caspase-12 was processed downstream of Apaf-1 and caspase-3, and neither overexpression nor knockdown of caspase-12 affected susceptibility of the cells to ER stress-induced cell death.

What is the function of caspase 12?

Caspase 12 is a prodeath protease located on the outer surface of the ER membrane and activated by ER stressors such as thapsigargin, tunicamycin, and proinflammatory cytokines in INS-1E cells and human islets [153,154].

Is caspase-3 activated by ER stress in neuroblastoma?

We also found that caspase-3, and not caspase-9 (a known mitochondrial apoptotic mediator), was mainly activated by ER stress. We generated the neuroblastoma cells that stably expressed caspase-12 and analyzed its influence on caspase-3 activation and vulnerability to ER stress.