JNK-dependent cell cycle stalling in G2 promotes survival and senescence-like phenotypes in tissue stress

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Tissue damage triggers apoptosis and compensatory proliferation to restore homeostasis.
• The c-Jun N-terminal kinase (JNK) pathway coordinates these responses in Drosophila imaginal discs.
• Proper spatial-temporal control of cell cycle regulation is crucial for effective tissue repair.

Purpose of the Study:

• To investigate the role of JNK signaling in cell cycle control during tissue damage and tumor formation.
• To elucidate the mechanisms by which JNK signaling affects cell cycle progression.
• To understand the implications of JNK-mediated cell cycle arrest in wound healing and disease.

Main Methods:

• Utilized Drosophila imaginal discs as a model system.
• Studied the effects of JNK signaling on cell cycle progression, specifically G2 phase duration.
• Investigated the role of the phosphatase String (Stg)/Cdc25 in JNK-induced cell cycle arrest.
• Examined the consequences of ectopic stg expression on cell survival, proliferation, and signaling.

Main Results:

• JNK signaling induces a dose-dependent extension of the G2 phase, causing transient or prolonged cell cycle arrest.
• This G2-stalling is mediated by the downregulation of String (Stg)/Cdc25.
• G2-stalling protects cells from JNK-induced apoptosis but impairs proliferation under chronic JNK overstimulation.
• Stalling promotes non-autonomous proliferation, suggesting paracrine signaling roles.

Conclusions:

• Transient G2-stalling is essential for effective wound healing by balancing apoptosis and proliferation.
• Chronic JNK overstimulation leading to persistent G2-stalling becomes detrimental, impacting proliferative capacity and potentially contributing to pathologies.
• Understanding JNK-mediated cell cycle control is critical for addressing chronic wound healing and tumorigenesis.