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The relationship between chromatin organization and RNA splicing
Icha, Jaroslav ; Valentová, Anna (referee) ; Staněk, David (advisor)
It is well known that RNA splicing and other pre-mRNA processing reactions happen cotranscriptionally. Surprisingly, there were recently discovered some chromatin features that had uneven distribution between exons and introns, which directly links chromatin organisation to splicing. This work summarizes all the studies that detected these chromatin patterns on exons and discuss their inconsistencies. In these studies nucleosomes were found to be preferentially positioned on exons, specific histone modifications and DNA methylation were also enriched on exons. These local patterns of chromatin organisation were evolutionarily conserved from mammals (human and mouse) to worm C. elegans and fly D. melanogaster. Their findings indicate that the role for chromatin structure in pre-mRNA splicing is to promote exon recognition. There are two mechanisms proposed for this role of chromatin in splicing. The first one is influence on RNA polymerase II elongation speed, and the second is specific recruitment of splicing machinery. In the near future we can expect studies searching for concrete examples of these two mechanisms and assessing their significance. Indeed it was reported very recently that H3K36me3 regulates alternative splicing via the second mechanism.
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Transport of ribosomal RNA within the nucleolus
Staněk, David ; Koberna, Karel ; Pliss, Artem ; Čtrnáctá, Vlasta ; Malínský, Jan ; Mašata, Martin ; Večeřová, Jaromíra ; Raška, Ivan
In the present study, we have explored the fact that incorporation of BrU into prerRNA did not interfere with pre-rRNA processing (11) and we have investigated the transport of non - isotopically labeled RNA within the nucleolus by means of transmissiion electron microscopy and confocal laser scanning microscopy.Within 20 minutes, BrU - labeled nucleolar RNA moved from the transcription sites in nucleolar DFC to GC. Double localization of bromouridine labeled RNA and fibrillarin revealed that only a ppart of the fibrillarin rich domains were transcriptionally active.
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