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The chromatin provides a structural organization in which the DNA can be compacted up to 10,000-20,000 fold. Nevertheless, this compaction achieved by the chromatin structure has to be highly dynamic and controlled in order to allow the different vital processes of the DNA to occur such as transcription, replication, DNA repair, chromosome segregation and recombination (mitosis and meiosis). Nucleosomes are the basic unit of chromatin compaction that are positioned throughout the vast genomic DNA in higher eukaryotes. A nucleosome consists of a pair of each histone protein H2A, H2B, H3 and H4 and the associated 147 base pairs (bp) of DNA. They are important contributors to overall chromatin organization. Structure Specific Recognition Protein 1 (SSRP1) is an HMG protein that has been investigated in Human. We have also carried out a Small interfering RNA (siRNA) strategy to reduce the expression of hSSRP1 in endothelial cells. The knocked down cells showed a clear reduction of beta-tubulin microtubules in the mitotic spindle and errors in their organization that led to a poor alignment of the chromosomes and missegregation. Furthermore, DNA repair and cytokinesis were also affected in the siRNA knockdowns. Immunolocalization of hSSRP1 and hSPT16 have shown that both could be involved in DNA repair when localising to the chromatin forming the FACT complex but also they could be deeply involved in spindle formation and organization in higher eukaryotes. Especially, since hSSRP1 localises in the centrioles. |
