Drosophila melanogaster MNK/Chk2 and p53 regulate multiple DNA repair and apoptotic pathways following DNA damage

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Ionizing radiation (IR) is a known genotoxic stressor.
• The p53 tumor suppressor protein plays a critical role in cellular responses to DNA damage.
• Understanding p53-mediated transcriptional regulation and apoptosis induction is crucial for cancer research.

Purpose of the Study:

• To elucidate the mechanisms by which ionizing radiation (IR) induces p53-dependent transcription and apoptosis in Drosophila melanogaster.
• To identify the key genes and pathways involved in the fruit fly's response to IR-induced DNA damage.

Main Methods:

• Genetic analysis of Drosophila melanogaster.
• Microarray analysis to assess genome-wide transcriptional changes.
• Analysis of gene mutations and deletions affecting apoptosis and DNA repair pathways.

Main Results:

• IR induces MNK/Chk2-dependent phosphorylation of p53 without altering protein levels, suggesting Mdm2-independent regulation.
• Genome-wide analysis revealed that p53 and MNK are essential for IR-induced transcriptional increases.
• Key proapoptotic targets of p53 include hid, reaper, and sickle; hid exhibits dosage-sensitive regulation of IR-induced apoptosis.
• p53 and MNK/Chk2 also regulate DNA repair genes, including Ku70 and Ku80.

Conclusions:

• Drosophila p53, activated by MNK/Chk2-dependent modification, orchestrates a global transcriptional response to DNA damage.
• This response encompasses the induction of error-prone DNA repair pathways and both intrinsic and extrinsic apoptosis pathways.
• The findings provide insights into conserved mechanisms of DNA damage response and tumor suppression.