[Topology of chromosomes in somatic cells. Part 1].

The interphase cell nucleus is a highly compartmentalized structure in which chromosomes are located in separate, defined places called chromosome territories (CTs). Chromosome territories with interchromatin compartments (ICs) and the nuclear matrix determine the nuclear architecture. There is a connection between nuclear architecture and genome function. The topology of the chromosomes in the nuclei of somatic cells is summarized here. It is known that the size and location of chromosome territories are tissue specific and depend on the cell cycle and the size of the chromosomes and the density of the genes which are actively transcribed. The correlation between transcriptional activity, the level of chromatin structure, and the location of the chromatin domains is outlined. The tendency of the heterochromatin regions and the telomeres to associate and the influence of this on the nuclear architecture is highlighted. Some studies are focused on the indirect role of the elements of the nuclear matrix and the inner-nuclear membrane in maintaining the correct locations of chromosome territories. The role of interchromatin granule clusters (IGCs), which are located in the nuclear matrix and which remain active in nuclear processes connected with chromosome topology, is further described. The influence of cell differentiation on chromosome location is pointed out. The topology of chromosomes in evolutionarily distinct species is also mentioned in this review. The reciprocal location of the chromosome territories is probably one of the important epigenetical factors influencing correct genome function. The high level of the organization of chromatin and chromatin modifications create the unique epigenetic pattern of a particular cell type. This seems to indicate a critical role of the spatial genomic organization in regulating gene expression.