Project description:CTCF is a master regulator that plays a role in genome architecture and gene expression. A key aspect of CTCF’s mechanism involves bringing together distant genetic elements for intra- and inter-chromosomal interactions. Evidence from epigenetic processes, such as X-chromosome inactivation (XCI), suggests that CTCF may carry out its functions through interacting RNAs. Using genome-wide approaches to investigate the relationship between CTCF’s RNA interactome and its epigenomic landscape, here we report that CTCF interacts with thousands of transcripts in mouse embryonic stem cells (mESC), many in close proximity to CTCF’s genomic binding sites. Biochemical analysis demonstrates that CTCF is a high-affinity RNA binding protein that contacts RNA directly and specifically. In the XCI model, CTCF binds the active and inactive X-chromosomes allele-specifically. At the X-inactivation center, Tsix RNA binds CTCF and targets CTCF to a region associated with X-chromosome pairing. Our work implicates CTCF-RNA interactions in long-range chromosomal interactions in trans and adds a new layer of complexity to CTCF regulation. The genome-wide datasets reported here will provide a useful resource for further study of CTCF-mediated epigenomic regulation. CTCF RNA interactome was identified by UV-crosslinking and immunoprecipitation followed by high-throughput sequencing (CLIP-seq), and was compared to CTCF's epigenomic landscape as obtained by chromatin immunoprecipitation (ChIP-seq).
Project description:An integrating APEX proximity labeling and chemical cross-linking coupled with mass spectrometry (CXMS) platform named APEX-CXMS for spatially resolved subcellular interactome profiling in a high-throughput ma
Project description:Erythropoiesis is dependent on the activity of transcription factors, including the erythroid-specific erythroid Kruppel-like factor (EKLF). ChIP followed by massively parallel sequencing (ChIP-Seq) is a powerful, unbiased method to map transfactor occupancy. We used ChIP-Seq to study the interactome of EKLF in mouse erythroid progenitor cells and more differentiated erythroblasts. We correlated these results with the nuclear distribution of EKLF, RNA-Seq analysis of the transcriptome, and the occupancy of other erythroid transcription factors. In progenitor cells, EKLF is found predominantly at the periphery of the nucleus, where EKLF primarily occupies the promoter regions of genes and acts as a transcriptional activator. In erythroblasts, EKLF is distributed throughout the nucleus, and erythroblast-specific EKLF occupancy is predominantly in intragenic regions. In progenitor cells, EKLF modulates general cell growth and cell cycle regulatory pathways, whereas in erythroblasts EKLF is associated with repression of these pathways. The EKLF interactome shows very little overlap with the interactomes of GATA1, GATA2, or TAL1, leading to a model in which EKLF directs programs that are independent of those regulated by the GATA factors or TAL1. (Blood.2011;118(17):e139-e148) We used ChIP-Seq to study the interactome of EKLF in mouse erythroid progenitor cells and more differentiated erythroblasts and RNA-Seq analysis of the transcriptome.