Researchers at the Weizmann Institute of Science have identified a molecular mechanism underlying compensatory proliferation, the ability of tissues to rebuild themselves after extensive damage. The phenomenon, known for approximately five decades through observations in various species including humans, has previously lacked a clear molecular explanation. The team’s findings, published in Nature Communications, reveal an unexpected role for caspases, enzymes traditionally associated with triggering cell death.
Using modern genetic tools to study fruit fly larvae exposed to ionizing radiation, the research team discovered two populations of death-resistant cells crucial to tissue repair. The first group, termed DARE cells, initiates the cellular self-destruction process but survives before executioner caspases can complete the destruction. These cells then multiply and repair damaged tissue. A second population, NARE cells, shows no activation of the initiator caspase yet still contributes to regeneration. Testing revealed that removal of DARE cells eliminated compensatory proliferation entirely, indicating their essential role in the process.
Investigation into the survival mechanism showed that a molecular motor protein prevents the apoptotic pathway from progressing beyond the initiator caspase stage in DARE cells. When researchers silenced this motor protein, DARE cells proceeded to die and tissue regeneration was impaired. Notably, overactivation of this same protein has been previously associated with cancerous tumor growth, suggesting a potential connection to cancer cell survival mechanisms.
The research revealed an additional concern: descendants of DARE cells that survived initial radiation exposure showed substantially increased resistance to cell death in subsequent exposures. Cells descended from the original death-resistant population demonstrated seven times greater resistance to cell death compared to cells in untreated tissue. This finding may help explain why tumors recurring after radiation therapy often become more aggressive and treatment-resistant, potentially informing future approaches to balance healthy tissue repair with reduced cancer recurrence risk.
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