Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such M-bM-^@M-^\bookmarkingM-bM-^@M-^] factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factorsM-bM-^@M-^Y developmental roles in gene activation. Three replicate chIP-seq data sets each are included for mitotic and asynchronously cycling cells; a single input lane from each condition is also included.
Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such “bookmarking” factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factors’ developmental roles in gene activation.
Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such “bookmarking” factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factors’ developmental roles in gene activation. Gene expression was assessed in asynchronously cycling cells in order to determine whether FoxA1 is disposed to bind to high- or low-expressed genes during mitosis. Heatmap analysis shows that FoxA1's mitotic targets are among the highest-expressed genes in asynchronous cells. Total RNA was collected from three different plates with asynchronous HUH7 cells using the RNeasy mini kit (Qiagen Valencia CA). Expression microarrays were performed with a Human Gene 1.OST array (Affymetrix) at the UPenn Microarray Core Facility and assessed using Partek.
Project description:During mitosis, RNA polymerase and most transcription factors are excluded from the chromosomes and transcription ceases. The transcriptional re-activation of the genome, following mitosis, requires the re-setting of cell-type specific programs that were initially established during development. However, only about one-fifth of transcription factors are retained on chromosomes throughout mitosis and a subset of these have been shown to facilitate target gene reactivation during mitotic exit. How such “bookmarking” factors bind to chromatin in mitosis and re-activate transcription is central to the stability of transcriptional programs across multiple cell cycles. We compared a diverse set of transcription factors involved in liver differentiation and found different modes of mitotic chromosome binding. The pioneer transcription factor FoxA1, which is among the first to bind liver genes in development, exhibits virtually complete mitotic chromosome binding, whereas other liver factors bind with a range of efficiencies. Yet genome-wide analysis shows that only about 15% of the FoxA1 interphase target sites are bound in mitosis; the latter include sites at genes for maintaining cell differentiation. FoxA1 mutants that perturb specific and nonspecific DNA binding reveal a significant contribution of nonspecific binding events in mitotic chromatin. Such nonspecific binding appears to spread from interphase FoxA1 targets and may serve as storage sites. The hierarchy of specific binding, nonspecific binding, partial chromatin binding, and failure to bind mitotic chromosomes reflects the temporal sequence of the factors’ developmental roles in gene activation. Gene expression was assessed in asynchronously cycling cells in order to determine whether FoxA1 is disposed to bind to high- or low-expressed genes during mitosis. Heatmap analysis shows that FoxA1's mitotic targets are among the highest-expressed genes in asynchronous cells.
Project description:SOX2 is part of the core network of transcription factors regulating embryonic stem cell pluripotency. We found that SOX2 has the ability to remain bound to mitotic chromosomes, in contrast to most transcription factors that are excluded from mitotic chromatin as transcription shuts down. We obtained a highly purified population of mitotic mouse embryonic stem cells and compared the genome-wide binding profile of SOX2 to that in asynchronous cells by Chromatin Immunoprecipitation followed by high throughput sequencing (ChIP-seq), and show that SOX2 remains bound to a small set of genes during mitosis.
Project description:In the associated paper, SERBP1 is shown to form granules in mitotic cells in a PKCɛ-dependent manner (M-bodies). We performed SERBP1 iCLIP in DLD1 cells that were either asynchronous or enriched for mitotic cells and after treatment with 2 hours of 500nM Blu577 or equivalent DMSO. We found that SERBP1 alters its positioning on rRNA in mitosis in a Blu577-dependent manner, identifying an alternative binding position that coincides with the formation of M-bodies. Mitotic enrichment was performed by single thymidine block, release in to G2 block with RO3306, and release and mitotic shake-off. The fastq files provided are demultiplexed, with adapters and barcodes trimmed and UMI sequences are found in the fastq headers.