Genomic distribution and functional specificity of human histone H1 subtypes
Seven linker histone H1 variants exist in human somatic cells with distinct prevalence among cell types and during differentiation. Despite being key chromatin structural components, it remains elusive how they participate in the regulation of nuclear processes. Moreover, it is not well understood w...
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| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2013 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/292370 |
| Acesso em linha: | http://hdl.handle.net/10803/292370 |
| Access Level: | acceso abierto |
| Palavra-chave: | Chromatin Epigenetics Histone H1 ChIP-seq Transcription star site LADs CpG islands Lamin B2 Cromatina Epigenètica Histona H1 Inici de transcripció Illes CpG Làmina B2 576 |
| Resumo: | Seven linker histone H1 variants exist in human somatic cells with distinct prevalence among cell types and during differentiation. Despite being key chromatin structural components, it remains elusive how they participate in the regulation of nuclear processes. Moreover, it is not well understood whether the different variants have specific roles or are differentially distributed along the genome. By taking advantage of specific antibodies for H1 variants and HA-tagged recombinant H1s expressed in breast cancer cells, the distribution of somatic variants H1.2 to H1.5, H1.0 and H1X has been investigated by combining ChIP-qPCR, ChIP-chip, and ChIP-seq analysis. All H1 variants bind gene promoters and are depleted from the TSS in active genes, and also from regulatory sites. The extension of H1 depletion at promoters is dependent on the transcriptional status of the gene and differs between variants. Analyses show that histone H1 is not uniformly distributed along the genome and differences among variants exist, being H1.2 the variant showing a more specific pattern and a strongest correlation with gene repression in breast cancer cells. Results suggest that different variants may be present at different chromatin types, and this may depend on the cell type, differentiation state, and whether cells are originated from a neoplastic process. In a second part of the thesis, it is shown that a previously reported H1.4 knock-down cell line presents and off-target effect against lamin B2. Therefore, it has been developed a new inducible knock-down cell line specifically inhibiting H1.4, which resembles previously characterized H1.2 knock-down. Finally, combined depletion of H1.4/lamin B2 and H1.2/H1.4 causes similar effects in T47D breast cancer cell line. |
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