mouse cofactor of brca1 (cobra1) is required for early embryogenesis鼠标辅助因子所需的brca1(cobra1)是早期胚胎发生.pdfVIP

Mouse Cofactor of BRCA1 (Cobra1) Is Required for Early Embryogenesis 1. 1. 1 2 1 1 Asma Amleh , Sreejith J. Nair , Jianlong Sun , Ann Sutherland , Paul Hasty , Rong Li * 1 Department of Molecular Medicine, Institute of Biotechnology, University of Texas, Health Science Center at San Antonio, San Antonio, Texas, United States of America, 2 Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America Abstract Background: Negative elongation factor (NELF) is a four-subunit protein complex conserved from Drosophila to humans. In vitro biochemical and tissue culture-based studies have demonstrated an important role of NELF in controlling RNA polymerase II (Pol II) pausing in transcription. However, the physiological significance of NELF function is not clear due to the lack of any genetic systems for studying NELF. Principal Findings: Here we show that disruption of the mouse B subunit of NELF (NELF-B), also known as cofactor of BRCA1 (Cobra1), causes inner cell mass (ICM) deficiency and embryonic lethality at the time of implantation. Consistent with the phenotype of the Cobra1 knockout (KO) embryos, knockdown of Cobra1 in mouse embryonic stem cells (ESCs) reduces the efficiency of colony formation and increases spontaneous differentiation. Cobra1-depleted ESCs maintain normal levels of Oct4, Nanog, and Sox2, master regulators of pluripotency in ESCs. However, knockdown of Cobra1 leads to precocious expression of developmental regulators including lymphoid enhancer-binding factor 1 (Lef1). Chromatin immunoprecipi- tation (ChIP) indicates that Cobra1 binds to the Lef1 promoter and modulates the abundance of promoter-bound RNA