A feedback loop that drives cell death and proliferation and its defect in intestinal stem cells

Area of Science:

• Cell biology
• Developmental biology
• Stem cell biology

Background:

• Cell death and proliferation are typically opposing cellular processes.
• Caspases are known executioners of apoptosis but possess elusive non-apoptotic functions.
• Understanding caspase roles is crucial for comprehending tissue homeostasis and disease.

Purpose of the Study:

• To investigate the role of caspases in Drosophila intestinal stem cells (ISCs).
• To elucidate the mechanisms underlying caspase-mediated non-apoptotic functions.
• To understand how ISCs achieve resistance to cell death.

Main Methods:

• Utilized Drosophila melanogaster as a model organism.
• Investigated caspase activation and its downstream effects in ISCs.
• Analyzed the interplay between caspases, JNK signaling, and DIAP1 inhibitor rpr.

Main Results:

• Caspase activation in ISCs induced massive cell proliferation instead of apoptosis.
• A positive feedback loop between caspases and JNK signaling was identified.
• Defective JNK to caspase signaling in ISCs favors proliferation.
• Two-tiered regulation of the DIAP1 inhibitor rpr (transcription and protein localization) was observed.

Conclusions:

• Caspases can execute non-apoptotic functions, such as driving cell proliferation.
• A regulatory circuit involving caspases and JNK balances cell proliferation and death.
• ISCs possess mechanisms for resisting cell death, involving caspase and rpr regulation.