E2F/DP Prevents Cell-Cycle Progression in Endocycling Fat Body Cells by Suppressing dATM Expression

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• E2F/DP transcription factors regulate cell proliferation and are crucial for development.
• The role of E2F/DP in differentiated tissues like the Drosophila larval fat body, which grows via endocycles, is not fully understood.
• Understanding the consequences of E2F/DP loss is essential for comprehending cell-cycle control mechanisms.

Purpose of the Study:

• To investigate the proteomic changes and cellular consequences of completely eliminating E2F/DP regulation in Drosophila.
• To elucidate the unexpected mechanism by which E2F/DP influences quiescence and cell-cycle progression in the larval fat body.
• To determine the role of DNA damage response pathways in the absence of functional E2F/DP complexes.

Main Methods:

• Proteomic profiling of Drosophila dDP mutants lacking functional E2F/DP complexes.
• Analysis of changes in the larval fat body, a tissue undergoing endocycles.
• Genetic manipulation, including ectopic expression and gene knockdown, to assess the function of dATM and its interaction with dE2F/dDP.

Main Results:

• Loss of dDP in the fat body leads to upregulation of dATM, activating DNA damage responses and promoting DNA synthesis.
• Ectopic dATM expression is sufficient to induce DNA synthesis in wild-type fat body cells.
• Reducing dATM levels in dDP-deficient fat bodies rescues cell-cycle control, improves tissue morphology, and extends animal lifespan.

Conclusions:

• In the Drosophila larval fat body, dE2F/dDP actively suppresses DNA damage signaling to maintain cell-cycle control and promote quiescence.
• The dE2F/dDP-dependent suppression of DNA damage response is critical for normal tissue development and organismal survival.
• This study reveals a novel function of E2F/DP in preventing aberrant DNA replication and damage signaling in differentiated cells.