Chromatin structure and gene expression: from the TMAC complex to the dREAM complex

Beattie, Gordon 2016. Chromatin structure and gene expression: from the TMAC complex to the dREAM complex. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Multi-subunit complexes such as the testis-specific meiotic arrest complex (TMAC) and the dREAM complex are context specific gene regulators, controlling genes involved in spermatogenesis and the G2/M transition respectively. The TMAC and dREAM complexes largely consist of subunits that are the same or paralogous to one another. One shared subunit, chromatin assembly factor 1, is also a component of the nucleosome remodelling factor complex, which has a similar testis gene expression phenotype to a TMAC mutant when its testis specific isoform, NURF301, is mutated. Therefore both complexes are thought to control gene expression, at least in part, through modifying chromatin either directly or through associations with chromatin remodellers. To investigate this further I have employed an unbiased approach for determining the positions of DNA bound proteins in vivo called Chromatin Particle Spectrum Analysis (CPSA) which involves micrococcal nuclease digestion of native chromatin and paired-end mode Illumina sequencing. Strikingly, in the cells which have many genes activated by TMAC, the spermatocytes, the transcriptional start sites of TMAC target genes lack coherent nucleosome positioning, which is a robust indicator of high gene expression in somatic cells. Disruption of TMAC does not decidedly alter this structure, suggesting that TMAC does not influence nucleosome positioning surrounding testis specific transcriptional start sites. In contrast, when analysing dREAM subunit deficient S2R+ cells, dREAM is found to contribute to the depletion of a nucleosome sized particle at the mid-point between divergently transcribed genes. This phenotype is linked with the involvement of dREAM in both enhancer blocking between proximal genes and its interaction with the nucleosome remodelling and deacetylase complex. Overall, I uncover the unique chromatin structure of highly expressed genes in spermatocytes, and implicate dREAM as being involved in nucleosome removal between divergent gene pairs.

Item Type:	Thesis (PhD)
Date Type:	Publication
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > QH Natural history > QH426 Genetics
Uncontrolled Keywords:	Drosophila
Date of First Compliant Deposit:	24 November 2016
Last Modified:	12 Jun 2019 02:55
URI:	https://orca.cardiff.ac.uk/id/eprint/96377

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