Project description:The study involved transcriptome analysis using RNA-seq knockdown of BORIS/CTCFL gene expression in K652 cancer cell line using inducible shRNA. The K562 cell line is the only cancer cell line that is known to be dependent on BORIS for proliferation and self-renewal of stemness. The goal of the study was to investigate the early/immediate transcriptional response to BORIS downregulation (over 10-fold reduction in protein level) using an inducible shRNA.
Project description:The study involved transcriptome analysis using RNA-seq knockdown of BORIS/CTCFL gene expression in K652 cancer cell line using inducible shRNA. The K562 cell line is the only cancer cell line that is known to be dependent on BORIS for proliferation and self-renewal of stemness. The goal of the study was to investigate the early/immediate small RNA transcriptional response to BORIS downregulation (over 10-fold reduction in protein level) using an inducible shRNA.
Project description:The identification of prognostic biomarkers is a priority for patients suffering from high-grade serous ovarian cancer (SOC), which accounts for >70% of ovarian cancer (OC) deaths. Meanwhile borderline ovarian cancer (BOC) is a low malignancy tumor and usually patients undergo surgery with low probabilities of recurrence. However, SOC remains the most lethal neoplasm due to the lack of biomarkers for early diagnosis and prognosis. In this regard BORIS (CTCFL), a CTCF paralog, is a promising cancer biomarker that is overexpressed and controls transcription in several cancer types, mainly in OC. Studies suggest that BORIS has an important function in OC by altering gene expression, but the effect and extent to which BORIS influences transcription in OC from a genome-wide perspective is unclear. Here we sought to identify BORIS target genes in an OC cell line (OVCAR3) with potential biomarker use in OC tumor samples. To achieve this, we performed in vitro knockout (KO) and knockdown (KD) experiments of BORIS in OVCAR3 cell line followed by expression microarrays and bioinformatics network enrichment analysis to identify relevant BORIS target genes.
Project description:CTCF and BORIS (CTCFL), two paralogous mammalian proteins sharing nearly identical DNA binding domains, are thought to function in mutually exclusive manners in DNA binding and transcriptional regulation. Here we show that these two proteins co-occupy a specific subset of regulatory elements consisting of clustered CTCF binding motifs (termed 2xCTSes). BORIS occupancy at 2xCTSes is largely invariant in BORIS-positive cancer cells, with the genomic pattern recapitulating the germline-specific BORIS binding to chromatin. In contrast to the single-motif CTCF target sites (1xCTSes), the 2xCTS elements are preferentially found at active promoters and enhancers, both in cancer and germ cells. 2xCTSes are also enriched in genomic regions that escape histone to protamine replacement in human and mouse sperm. Depletion of BORIS gene leads to altered transcription of a large number of genes and the differentiation of K562 cells, while the ectopic expression of this CTCF paralog leads to specific changes in transcription in MCF7 cells. In summary, we discover two functionally and structurally different classes of CTCF binding regions, 2xCTSes and 1xCTSes, revealed by their predisposition to bind BORIS. We propose that 2xCTSes play key roles in the transcriptional program of cancer and germ cells Genome-wide mapping of CTCF and BORIS occupancies in both germ and cancer cells. ChIP-seq and expression profiling by high throughput sequencing
Project description:CTCF and CTCFL DNA binding profile in CTCFL induced and non-induced ES cells.CTCF is a highly conserved and essential zinc finger protein that in conjunction with cohesin organizes chromatin into loops, thereby regulating gene expression and epigenetic events. The function of CTCFL or BORIS, the testis-specific paralogue of CTCF, is less clear. Here, we show that CTCFL is only transiently present during spermatogenesis, prior to the onset of meiosis, when the protein co-localizes in nuclei with ubiquitously expressed CTCF. Our data show that CTCFL is functionally different from CTCF and its absence in mice causes sub-fertility due to a partially penetrant testicular atrophy. Genome-wide studies reveal that CTCFL and CTCF bind similar consensus sequences. However, only ~2000 out of the ~5,700 CTCFL and ~31,000 CTCF binding sites overlap. CTCFL binds promoters with loosely assembled nucleosomes, whereas CTCF favors consensus sites surrounded by phased nucleosomes. Thus, nucleosome dynamics specifies the genome-wide binding of CTCFL and CTCF. We propose that the transient expression of CTCFL in spermatogonia and preleptotene spermatocytes serves to occupy a subset of promoters and maintain the expression of male germ cell genes ChIP-seq for CTCF (with CTCF antibody) and CTCFL (with V5 antibody) in CTCFL_V5_GFP induced and non-induced ES cells