Caspase-12 processing and fragment translocation into nuclei of tunicamycin-treated cells

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Endoplasmic reticulum (ER) stress is implicated in cellular dysfunction and death.
• Caspase-12, an ER-resident protease, is activated during ER stress but its precise role in cell death remains unclear.
• Understanding caspase-12 processing is crucial for elucidating ER stress-induced apoptosis pathways.

Purpose of the Study:

• To investigate the relationship between specific caspase-12 processing events and cell death induced by ER stress.
• To determine the cleavage sites involved in caspase-12 activation and their functional consequences.
• To explore the subcellular localization of processed caspase-12 during ER stress-induced apoptosis.

Main Methods:

• Generation of specific antibodies against caspase-12 cleavage sites (D318 and D341).
• Overexpression of wild-type and mutated caspase-12 in cells.
• Induction of ER stress using tunicamycin.
• Immunohistochemical analysis to detect caspase-12 processing and localization.

Main Results:

• Caspase-12 overexpression led to autoprocessing at D318 but did not induce cell death.
• Tunicamycin treatment induced caspase-12 processing at both D318 and D341, correlating with cell death.
• Processed caspase-12 fragments were detected in the ER and translocated to the nucleus in apoptotic cells.

Conclusions:

• Caspase-12 autoprocessing at D318 alone is insufficient for ER stress-induced cell death.
• Processing at both N-terminal and C-terminal regions, including D341, is essential for caspase-12's role in ER stress-induced apoptosis.
• Nuclear translocation of processed caspase-12 suggests its direct involvement in apoptotic events within the nucleus.