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Updated: Jun 13, 2026
Isolation and Transplantation of Different Aged Murine Thymic Grafts.
Published on: May 13, 2015
Clonally expanding thymocytes having lineage capability in gamma-ray-induced mouse atrophic thymus
Takashi Yamamoto1, Shin-ichi Morita, Rieka Go
1Department of Molecular Genetics, Niigata University Graduate School of Medical and Dental Sciences, Chuo-ku, Niigata, Japan.
Purpose:
To characterize, in the setting of gamma-ray-induced atrophic thymus, probable prelymphoma cells showing clonal growth and changes in signaling, including DNA damage checkpoint.
Methods And Materials:
A total of 111 and 45 mouse atrophic thymuses at 40 and 80 days, respectively, after gamma-irradiation were analyzed with polymerase chain reaction for D-J rearrangements at the TCRbeta locus, flow cytometry for cell cycle, and Western blotting for the activation of DNA damage checkpoints.
Results:
Limited D-J rearrangement patterns distinct from normal thymus were detected at high frequencies (43 of 111 for 40-day thymus and 21 of 45 for 80-day thymus). Those clonally expanded thymocytes mostly consisted of CD4(+)CD8(+) double-positive cells, indicating the retention of lineage capability. They exhibited pausing at a late G1 phase of cell cycle progression but did not show the activation of DNA damage checkpoints such as gammaH2AX, Chk1/2, or p53. Of interest is that 17 of the 52 thymuses showing normal D-J rearrangement patterns at 40 days after irradiation showed allelic loss at the Bcl11b tumor suppressor locus, also indicating clonal expansion.
Conclusion:
The thymocytes of clonal growth detected resemble human chronic myeloid leukemia in possessing self-renewal and lineage capability, and therefore they can be a candidate of the lymphoma-initiating cells.
