@article{Eduardo Anguita_Ana Villegas_Francisco Iborra_Aurora Hernández_2010, place={Pavia, Italy}, title={GFI1B controls its own expression binding to multiple sites}, volume={95}, url={https://haematologica.org/article/view/5473}, DOI={10.3324/haematol.2009.012351}, abstractNote={<strong>Background</strong> Transcription factors play essential roles in both normal and malignant hematopoiesis. This is the case for the growth factor independent 1b (GFI1B) transcription factor, which is required for erythroid and megakaryocytic differentiation and over-expressed in leukemic patients and cell lines.<strong>Design and Methods</strong> To investigate <em>GFI1B</em> regulation, we searched for multispecies conserved non-coding elements between <em>GFI1B</em> and neighboring genes. We used a formaldehyde-assisted isolation of regulatory elements (FAIRE) assay and DNase1 hypersensitivity to assess the chromatin conformation of these sites. Next, we analyzed transcription factor binding and histone modifications at the <em>GFI1B</em> locus including the conserved non-coding elements by a chromatin immunoprecipitation assay. Finally, we studied the interaction of the <em>GFI1B</em> promoter and the conserved non-coding elements with the chromatin conformation capture technique and used immunofluorescence to evaluate GFI1B levels in individual cells.<strong>Results</strong> We localized several conserved non-coding elements containing multiple erythroid specific transcription factor binding sites at the <em>GFI1B</em> locus. In GFI1B-expressing cells a subset of these conserved non-coding elements and the promoter adopt a close spatial conformation, localize with open chromatin sites, harbor chromatin modifications associated with gene activation and bind multiple transcription factors and co-repressors.<strong>Conclusions</strong> Our findings indicate that <em>GFI1B</em> regulatory elements behave as activators and repressors. Different protein levels within a cell population suggest that cells must activate and repress <em>GFI1B</em> continuously to control its final level. These data are consistent with a model of <em>GFI1B</em> regulation in which GFI1B binds to its own promoter and to the conserved non-coding elements as its levels rise. This would attract repressor complexes that progressively down-regulate the gene. <em>GFI1B</em&gt; expression would decrease until a stage at which the activating complexes predominate and expression increases.}, number={1}, journal={Haematologica}, author={Eduardo Anguita and Ana Villegas and Francisco Iborra and Aurora Hernández}, year={2010}, month={Jan.}, pages={36-46} }