Institute Cytology and Genetics

Laboratory of Cell Molecular Biology

Head S.S.Bogachev, Dr.Biol.Sci.

A schematic representation for the organization of precentromeric heterochromatin in the contact site with the nuclear membrane in D. melanogaster. Thick line highlights the regions where the specific centromeric repeat is located. The physical movement (sliding) of chromatin along the lamin filaments is provided by this repetitive DNA and the dynamic state of polymerized lamin

The dynamics of the interaction between the karyoskeleton structures and chromatin in Drosophila melanogaster, the classical object of molecular-genetic studies, is the main topic of research at the Laboratory. The chromatin components associated in vivo with lamin, the major protein of the cytoskeleton, were characterized. It was found that there are specific centromeric loci associated with lamin in each chromosome. The chromatin interactions provide the orientation of the nuclei with respect to the nuclear volume. A number of interaction types was demonstrated for lamin-associated chromosome DNA. Based on the results obtained at the laboratory, a hypothesis for the types of chromatin shifts within the nucleus was proposed. Shifts of two types were distinguished.

Type 1, change in the topology of the sites with respect to the inner nuclear structure as a consequence of regrouping of the composing elements of the cytoskeleton occurrring either when cells enter the differentiation pathway or during successive cell divisions.

Type 2, sliding of chromatin along the elements and provided by them. The concept of the dynamics of interaction between chromatin and karyoskeleton proteins was developed. It is suggested that there exists a system of mediators (lamins-M/SAR DNA) between the two karyoskeleton components (the nuclear matrix and lamin). These mediators ensure the structural transformations in the nucleus.