A Dedicated Evolutionarily Conserved Molecular Network Licenses Differentiated Cells to Return to the Cell Cycle

Area of Science:

• Cell Biology
• Molecular Biology
• Regenerative Medicine

Background:

• Differentiated cells typically exit the cell cycle.
• Tissue injury necessitates cell cycle re-entry for repair.
• Paligenosis is a conserved regeneration program involving mTORC1.

Purpose of the Study:

• To elucidate the molecular network controlling mTORC1 during palingenesis.
• To investigate the roles of DDIT4 and IFRD1 in this process.
• To understand the regulation of cell cycle re-entry in differentiated cells.

Main Methods:

• Analysis of mouse pancreatic acinar and gastric chief cells undergoing palingenesis.
• Genetic manipulation of DDIT4 and IFRD1.
• Assessment of mTORC1 activity, p53 accumulation, and cell proliferation.

Main Results:

• DDIT4 suppresses mTORC1, initiating cellular component degradation.
• IFRD1 inhibits p53 accumulation, allowing mTORC1 reactivation and proliferation.
• Loss of DDIT4 or IFRD1 disrupts palingenesis, leading to impaired regeneration.

Conclusions:

• A conserved molecular network involving DDIT4 and IFRD1 regulates mTORC1 during palingenesis.
• This network is crucial for enabling differentiated cells to re-enter the cell cycle for tissue repair.
• DDIT4/IFRD1 function as critical checkpoints in the regenerative process across species.