Examination of the Transcription Factors Acting in Bone Marrow
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THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY (PHD) Examination of the transcription factors acting in bone marrow derived macrophages by Gergely Nagy Supervisor: Dr. Endre Barta UNIVERSITY OF DEBRECEN DOCTORAL SCHOOL OF MOLECULAR CELL AND IMMUNE BIOLOGY DEBRECEN, 2016 Table of contents Table of contents ........................................................................................................................ 2 1. Introduction ............................................................................................................................ 5 1.1. Transcriptional regulation ................................................................................................... 5 1.1.1. Transcriptional initiation .................................................................................................. 5 1.1.2. Co-regulators and histone modifications .......................................................................... 8 1.2. Promoter and enhancer sequences guiding transcription factors ...................................... 11 1.2.1. General transcription factors .......................................................................................... 11 1.2.2. The ETS superfamily ..................................................................................................... 17 1.2.3. The AP-1 and CREB proteins ........................................................................................ 20 1.2.4. Other promoter specific transcription factor families .................................................... 26 1.3. Nuclear receptors ............................................................................................................... 31 1.4. Transcription factors in macrophage development ........................................................... 37 1.5. NGS methods in functional genomics ............................................................................... 40 1.5.1. Getting and aligning raw NGS data ............................................................................... 40 1.5.2. The determination of read and motif enrichments ......................................................... 43 2. Aims of the study ................................................................................................................. 47 3. Materials and Methods ......................................................................................................... 49 3.1. The differentiation of bone marrow derived macrophage (BMDM) cells ........................ 49 3.2. Chromatin immunoprecipitation coupled with next-generation sequencing .................... 49 3.3. ChIP-seq analysis .............................................................................................................. 51 3.3.1. Primary analysis ............................................................................................................. 51 3.3.2. The determination of nucleosome-free regions (NFRs) ................................................. 51 3.3.3. Peak prediction ............................................................................................................... 52 2 3.3.4. Secondary analyses ........................................................................................................ 52 3.4. Global run-on sequencing (GRO-seq) ............................................................................... 53 3.5. GRO-seq analysis .............................................................................................................. 54 3.5.1. Primary analysis ............................................................................................................. 54 3.5.2. The determination of transcripts .................................................................................... 54 3.5.3. The annotation of transcripts .......................................................................................... 56 3.5.4. The expressional analysis of nascent transcripts ............................................................ 56 3.5.5. The annotation of RXR-bound regulatory regions ......................................................... 57 3.6. RNA-seq ............................................................................................................................ 57 3.7. RNA-seq analysis .............................................................................................................. 58 3.8. Domain predictions based on the CTCF and RAD21 “co-peaks” .................................... 59 3.9. Chromosome conformation capture (3C) .......................................................................... 59 3.10. 3C-sequencing ................................................................................................................. 60 3.11. 3C-seq analysis ................................................................................................................ 60 3.12. The phylogenetic comparison of AP-1/CREB related bZIP proteins ............................. 61 4. Results .................................................................................................................................. 62 4.1. Determining the putative regulatory regions of macrophages based on histone coverage information ............................................................................................................................... 62 4.2. Determining macrophage specific transcription factors from NFR predictions ............... 67 4.3. The examination of histone patterns near PU.1 binding sites ........................................... 71 4.4. Combining NFR data to get further putative regulators .................................................... 75 4.5. The examination of the RXR cistrome in macrophages ................................................... 78 4.6. The determination of the nascent transcriptome of macrophages ..................................... 82 4.7. The examination of the gene expressional changes of TFs upon RXR activation ............ 85 4.8. The annotation of the putative regulatory regions .......................................................... 100 3 4.9. Putative binding elements of the annotated RXR peaks ................................................. 106 4.10. The examination of functional domains ........................................................................ 107 5. Discussion .......................................................................................................................... 114 6. Keywords / kulcsszavak ..................................................................................................... 119 7. Summary ............................................................................................................................ 120 Összefoglalás .......................................................................................................................... 121 8. Abbreviations ..................................................................................................................... 122 9. Acknowledgements ............................................................................................................ 131 10. References ........................................................................................................................ 132 4 1. Introduction 1.1. Transcriptional regulation 1.1.1. Transcriptional initiation Transcriptional initiation, elongation and termination are main steps of nascent RNA synthesis. As once RNA polymerase has been launched, it runs along the gene, of these steps – in our present knowledge – initiation may provide the most extended regulatory possibilities. In eukaryotes, the pre-initiation complex (PIC) assembled on the transcription factor binding sites (TFBSs) of the promoter of protein coding genes is composed of transcription factors (TFs), their co-regulators, as well as RNA polymerase II (Pol II) (Figure 1) (Green, Trends Biochem Sci., 2000; Grünberg and Hahn, Trends Biochem Sci., 2013). Pol II also is a complex built up from RNA polymerase II B (RPB1-12) subunits coded by Polr2a- k genes (Ruprich-Robert and Thuriaux, Nucleic Acids Res., 2010). To launch Pol II, not only the presence of a large number of regulatory proteins (Tsai and Nussinov, Biochem J., 2011), but also their enzymatic activity is needed: beside the multiple serine phosphorylation on the carboxy-terminal domain (CTD) of RPB1, helicase and topoisomerase activities are also indispensable to start PolII (Heidemann et al., Biochim Biophys Acta., 2013; Baranello et al., Transcription, 2013). Once PIC has been formed, PolII synthesizes truncated and elongated transcripts in an abortive and productive manner, respectively (Dvir, Biochim Biophys Acta., 2002; Mandal et al., PNAS, 2004; Core et al., Science, 2008; Gaertner and Zeitlinger, Development, 2014). This former property may be needed for further regulatory functions, e.g. the operation of short transcripts in some comparable ways as happens in prokaryotes. In E. coli, the abortive transcript of bacteriophage T7 gene 10 has an antiterminator effect thus facilitating the expression of the further promoterless genes of the polycistron located directly downstream (Lee et al., Nucleic Acids Res., 2010). In eukaryotes, the ratio of the truncated and elongated 5 transcripts correlates with gene expression (Core et al., Science, 2008), but the possible roles of the short products still remain mostly unknown (Seila et