Multipotent hematopoietic cells susceptible to alternative double-strand break repair pathways that promote genome rearrangements.
Chromosomal translocations are a hallmark of hematopoietic malignancies. The initial molecular events or pathways that lead to translocations in hematopoietic cells are largely unknown, particularly in the stem cell-enriched population postulated to be the initial target for these events. We used in vitro differentiation of mouse embryonic stem (ES) cells combined with an I-SceI endonuclease double-strand break (DSB) repair assay to determine the relative susceptibility of isogenic hematopoietic subpopulations to DSB-induced translocations and the mechanisms that generate them. DSB-induced reciprocal translocations were frequently observed in multipotent progenitors but significantly suppressed in actively proliferating myeloid cells. Most reciprocal translocations in multipotent progenitors resulted from repair consistent with single-strand annealing followed by gap repair. Overexpression of Rad51, a protein central to DNA strand exchange and recombination, did not further increase the frequency of recovered translocations but did increase the frequency of long-tract gene conversion events associated with loss of heterozygosity and tandem duplications. These data directly demonstrate that hematopoietic multipotent progenitor cells are particularly susceptible to the formation of chromosomal rearrangements analogous to those observed in human hematopoietic malignancies. This particular subpopulation apparently represents a window of opportunity for the initiation of potentially oncogenic events following DNA damage.
Francis
Richard
R
Institute for Cancer Genetics, Department of Pathology, Columbia University, New York, New York 10032, USA.
Richardson
Christine
C
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D053903:DNA Breaks, Double-Stranded; D017931:DNA Primers / Q000235:genetics; D004260:DNA Repair; D005785:Gene Conversion; D020440:Gene Duplication; D015870:Gene Expression; D015321:Gene Rearrangement; D019337:Hematologic Neoplasms / Q000209:etiology / Q000235:genetics; D006410:Hematopoiesis / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D019656:Loss of Heterozygosity; D051379:Mice; D039902:Multipotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D014178:Translocation, Genetic
D017931:DNA Primers; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse