Distribution of Nucleophosmine Proteins (B23) and Hyston H4 Lysine 20 (Н4К20me3) in the Granule Cells of the Rat Brain Cerebellum

Abstract

The purpose of this study was to study the relative distribution of the nucleophosmin (B23) protein and histone H4K20me3 in the granule cells of the rat cerebellar cortex. The material for the study was the samples of the cerebellum of mature male rats of the Wistar line (n = 8). Using the methods of immunocytochemistry and confocal laser microscopy for the first time, the features of the distribution of the nucleophosmin protein in the nuclei of the cerebellar granule cells were studied. In the nucleolus, a region that was characterized by the lack of the B23 protein and, supposedly, a fibrillar center was found. In addition to the nucleolus, nucleophosmin was detected (in a smaller amount) in the nucleoplasm of the cell granules. Using the method of confocal laser microscopy and three-dimensional reconstruction, we demonstrated the presence of zones of colocalization of the B23 protein and histone H4K20me3 within the nucleolus and nucleoplasm of the cell granules. It was shown that histone H4K20me3 is part of the perinucleolus heterochromatin, from which various protrusions often extend into the interior of the nucleolus. Clusters of the extranucleolus nucleophosmin were also often colocalized with heterochromatin blocks. However, nonnucleolus clusters of nucleophosmin that were not associated with heterochromatin blocks were also present. The results obtained make a significant addition to the existing ideas about the structural and functional organization of the nucleus of the cerebellar granule cells.