Nuclear localization of translocation partners in differentiating B-cells.

We studied the nuclear localization and relative position in the nuclear space of malignant translocation partner genes c-Myc, CCND1, and IGH locus in naive and differentiating B cells. We have shown that, during B-cell maturation, c-Myc and IGH loci become closer to each other. In differentiating lymphocytes, those alleles of c-Myc and IGH that are in close spatial proximity to each other are closer to the nucleolus.

The distribution of tightly bound proteins along the DNA chain reflects the type of cell differentiation.

Distribution of proteins tightly bound to DNA (TBP) along the DNA chain was found to depend on the cell lineage. DNA sequences coding for alpha globin genes are preferentially represented in the TBP-associated DNA fractions isolated from erythroid cells (erythroblasts, mature erythrocytes, differentiated and non-differentiated Friend erythroleukemia cells), but not from cultured fibroblast cells. In transcriptionally active nuclei, complexes of TBP interact with the nuclear matrix, while in mature erythrocytes this interaction disappears.