Genetic and physical mapping of the murine Sox1 gene

Dynamic repositioning of genes in the nucleus of lymphocytes preparing for cell division

We show that several transcriptionally inactive genes localize to centromeric heterochromatin in the nucleus of cycling but not quiescent (noncycling) primary B lymphocytes. In quiescent cells, centromeric repositioning of inactive loci was induced after mitogenic stimulation. A dynamic repositioning of selected genes was also observed in developing T cells. Rag and TdT loci were shown to relocate to centromeric domains following heritable gene silencing in primary CD4+8+ thymocytes, but not in a phenotypically similar cell line in which silencing occurred but was not heritable. Collectively, these data indicate that the spatial organization of genes in cycling and noncycling lymphocytes is different and that locus repositioning may be a feature of heritable gene silencing.

Sox genes find their feet

The identification of the mammalian testis-determining factor, SRY, led to the description of a new class of genes encoding transcription factors, the SOX gene family. SOX proteins display properties of both classical transcription factors and architectural components of chromatin. The dynamic and diverse patterns of expression of SOX genes and analysis of mutations in humans, mice and Drosophila suggest that SOX factors play key roles in decisions of cell fate during diverse developmental processes.