Age-Dependent Differences in Radiation-Induced DNA Damage Responses in Intestinal Stem Cells

Area of Science:

• Molecular Biology
• Developmental Biology
• Radiation Oncology

Background:

• Age at exposure significantly modifies radiation-induced cancer risk.
• Understanding age-related differences in radiation carcinogenesis is crucial but poorly understood.

Purpose of the Study:

• To compare radiation-induced DNA damage responses in Lgr5+ and Lgr5- intestinal stem cells between infant and adult mice.
• To elucidate the mechanisms underlying age-dependent susceptibility to radiation carcinogenesis.

Main Methods:

• Utilized Lgr5-eGFP-ires-Cre mice for stem cell tracking.
• Performed three-dimensional immunostaining and RNA sequencing.
• Analyzed apoptosis, mitotic index, and p53 activation post-irradiation.

Main Results:

• Radiation induced apoptosis and mitotic index more efficiently in adult Lgr5- stem cells than Lgr5+ stem cells.
• Infant intestinal stem cells showed similar responses regardless of Lgr5 expression.
• Adult stem cells exhibited rapid p53 activation and greater gene expression variability, with enriched cell cycle and DNA repair pathways post-irradiation.

Conclusions:

• Radiation-induced DNA damage responses in mouse intestinal crypts differ significantly between infants and adults.
• These age-dependent differences in stem cell response may explain varying susceptibility to radiation-induced cancer.
• Findings highlight critical developmental windows in radiation response.