Localisation and distance between ABL and BCR genes in interphase nuclei of bone marrow cells of control donors and patients with chronic myeloid leukaemia

Abstract

Quantitative measurements of the nuclear localisation of the ABL and BCR genes and the distance between them were performed in randomly oriented bone marrow cells of control donors and patients with chronic myeloid leukaemia (CML). Most ABL and BCR genes (75%) are located at a distance of 20-65% of the local radius from the nuclear centre to the nuclear membrane. A chimeric BCR-ABL gene located on a derivative chromosome 22 resulting from t(9;22)(q34;q11) [the so-called Philadelphia (Ph) chromosome] as well as the intact ABL and BCR genes of patients suffering from chronic myeloid leukaemia are also located mostly in this region, which has a mean thickness of 2 microns in bone marrow cells. We have not found any significant differences in the location of the two genes in the G1 and G2 phases of the cell cycle, nor between bone marrow cells and stimulated lymphocytes. Irradiation of lymphocytes with a dose of 5 Gy of gamma-rays results in a shift of both genes to the central region of the nucleus (0-20% of the radius distant from the nuclear centre) in about 15% of the cells. The minimum distance between one ABL and one BCR gene is less than 1 micron in 47.5% of bone marrow cells of control donors. Such a small distance is found between homologous ABL and between homologous BCR genes in only 8.1% and 8.4% of cells, respectively. It is possible that the relative closeness of nonhomologous ABL and BCR genes in interphase nuclei of bone marrow cells could facilitate translocation between these genes. In 16.4% of bone marrow cells one ABL and one BCR gene are juxtaposed (the distance between them varies from 0-0.5 micron) and simulate the Ph chromosome. This juxtaposition is the result of the projection of two genes located one above another into a plane, as follows from the probability calculation.

Influence of Cell Fixation on Chromatin Topography

“…For reconstruction of 3D from 2D data see Ref. (10). The symbols CG and GC represent the center of nucleus-to-gene distance and gene-to-gene distance, respectively, where G can be N 3 for the centromere specific for chromosome 3, A for ABL gene, and B for BCR gene.…”

BCR-ABL in Chronic Myelogenous Leukemia – How Does It Work?

“…Further, the mechanism whereby genes normally present on chromosomes 9 and 22 come together, if not by chance, is also unknown. There is some evidence that chromosomes 9 and 22 may be in closer proximity in interphase cells than would be expected by chance [13, 14]. Homologous sequences have been identified on chromosomes 9 and 22 that might facilitate aberrant recombination [15].…”

State‐of‐the‐art FISHing: Automated analysis of cytogenetic aberrations in interphase nuclei

“…The first automated detection of BCR/ABL1 gene rearrangement in patients with chronic myeloid leukemia was performed by Kozubek et al, and Lukasova et al; our workgroup also set up a method for this purpose and REVIEW ARTICLE published a detailed description about the automated evaluation (30,35,108). Due to the evolution of translocation FISH probe kits (single-fusion ?…”