Project description:We assessed whether human transcripts expressed in an aneuploid mouse that carries human chromosome 21 (HsChr21) are spliced in a human-specific or mouse-specific fashion. In almost all cases, human-specific alternative splicing is maintained in the mouse nucleus. Species-specific splicing therefore appears to be primarily directed by cis-acting elements, rather than changes in the levels or activities of trans-acting factors. Approximately 485 million Illumina 50-nt sequence reads were generated for brain and liver tissues from normal human, Tc0 (wildtype) mouse and Tc1 mouse strains. Sequence reads were mapped to splice junctions and %in levels were estimated.
Project description:We assessed whether human transcripts expressed in an aneuploid mouse that carries human chromosome 21 (HsChr21) are spliced in a human-specific or mouse-specific fashion. In almost all cases, human-specific alternative splicing is maintained in the mouse nucleus. Species-specific splicing therefore appears to be primarily directed by cis-acting elements, rather than changes in the levels or activities of trans-acting factors.
Project description:Primary piRNAs in Drosophila ovarian somatic cells arise from piRNA cluster transcripts and the 3′ UTRs of a subset of mRNAs, including Traffic jam (Tj) mRNA. However, it is unclear how these RNAs are determined as primary piRNA sources. Here, we identify a cis-acting 100-nt fragment in the Tj 3′ UTR that is sufficient for producing artificial piRNAs from unintegrated DNA. These artificial piRNAs were effective in endogenous gene transcriptional silencing. Yb, a core component of primary piRNA biogenesis center Yb bodies, directly bound the Tj-cis-element. Disruption of this interaction markedly reduced piRNA production. Thus, Yb is the trans-acting partner of the Tj-cis-element. Yb-CLIP revealed that Yb-binding correlated with somatic piRNA production but Tj-cis-element downstream sequences produced few artificial piRNAs. Thus, Yb determines primary piRNA sources by two modes of action; primary binding to cis-elements to specify substrates, and secondary binding to downstream regions to increase diversity in piRNA populations. HITS-CLIP of Yb in OSCs (Ovarian Somatic Cells) depleted for tj cis-element, and small RNA sequencing of Piwi-piRNAs in OSCs depleted for tj cis-element.
Project description:Many genes harbour multiple transcriptional enhancers that act concomitantly to achieve robust and precise spatial-temporal expression. In vertebrates, however, the mechanisms underlying cooperation between cis-acting elements are poorly documented. The mouse gene Krox20 encodes a transcription factor required for the specification of two segments (rhombomeres) of the developing hindbrain. In rhombomere 3, Krox20 is subject to positive feedback, governed by enhancer A, which is directly bound by the KROX20 protein, whereas another element, C, distant from 70 kb, was supposed to be only required for initiation of expression. Here, using both enhancer knock-outs and investigations of chromatin organisation, we show that element C possesses a dual activity: besides its classical enhancer function, it is also permanently required in cis to potentiate element A autoregulatory activity, by increasing its chromatin accessibility. This work uncovers a novel, asymmetrical, long-range mode of cooperation between cis-acting elements that might be essential to avoid promiscuous activation of positive autoregulatory elements.
Project description:Many genes harbour multiple transcriptional enhancers that act concomitantly to achieve robust and precise spatial-temporal expression. In vertebrates, however, the mechanisms underlying cooperation between cis-acting elements are poorly documented. The mouse gene Krox20 encodes a transcription factor required for the specification of two segments (rhombomeres) of the developing hindbrain. In rhombomere 3, Krox20 is subject to positive feedback, governed by enhancer A, which is directly bound by the KROX20 protein, whereas another element, C, distant from 70 kb, was supposed to be only required for initiation of expression. Here, using both enhancer knock-outs and investigations of chromatin organisation, we show that element C possesses a dual activity: besides its classical enhancer function, it is also permanently required in cis to potentiate element A autoregulatory activity, by increasing its chromatin accessibility. This work uncovers a novel, asymmetrical, long-range mode of cooperation between cis-acting elements that might be essential to avoid promiscuous activation of positive autoregulatory elements.
Project description:Many genes harbour multiple transcriptional enhancers that act concomitantly to achieve robust and precise spatial-temporal expression. In vertebrates, however, the mechanisms underlying cooperation between cis-acting elements are poorly documented. The mouse gene Krox20 encodes a transcription factor required for the specification of two segments (rhombomeres) of the developing hindbrain. In rhombomere 3, Krox20 is subject to positive feedback, governed by enhancer A, which is directly bound by the KROX20 protein, whereas another element, C, distant from 70 kb, was supposed to be only required for initiation of expression. Here, using both enhancer knock-outs and investigations of chromatin organisation, we show that element C possesses a dual activity: besides its classical enhancer function, it is also permanently required in cis to potentiate element A autoregulatory activity, by increasing its chromatin accessibility. This work uncovers a novel, asymmetrical, long-range mode of cooperation between cis-acting elements that might be essential to avoid promiscuous activation of positive autoregulatory elements.
Project description:Primary piRNAs in Drosophila ovarian somatic cells arise from piRNA cluster transcripts and the 3′ UTRs of a subset of mRNAs, including Traffic jam (Tj) mRNA. However, it is unclear how these RNAs are determined as primary piRNA sources. Here, we identify a cis-acting 100-nt fragment in the Tj 3′ UTR that is sufficient for producing artificial piRNAs from unintegrated DNA. These artificial piRNAs were effective in endogenous gene transcriptional silencing. Yb, a core component of primary piRNA biogenesis center Yb bodies, directly bound the Tj-cis-element. Disruption of this interaction markedly reduced piRNA production. Thus, Yb is the trans-acting partner of the Tj-cis-element. Yb-CLIP revealed that Yb-binding correlated with somatic piRNA production but Tj-cis-element downstream sequences produced few artificial piRNAs. Thus, Yb determines primary piRNA sources by two modes of action; primary binding to cis-elements to specify substrates, and secondary binding to downstream regions to increase diversity in piRNA populations.
Project description:We have combined the 4C chromosome conformation capture protocol with high throughput, genome-wide sequence analysis to characterise in full a cis-acting regulatory network at a single locus. In contrast to methods which identify large interacting regions (10-1000kb), the 4C approach provides a comprehensive, high resolution analysis of a specific locus with the aim of defining, in detail, all cis- regulatory elements controlling a single gene or gene cluster. Using the human M-NM-1-globin locus as a model we detected all known local and long-range interactions with this gene cluster. In addition we identified two interactions with genes located 300 kb (NME4) and 625 kb (FAM173a) from the M-NM-1-globin cluster. Using paired-end sequencing it was possible for the first time to identify interactions between specific subsets of cis-regulatory elements in populations of cells and within individual cells. Two biological replicates of 4C amplification from the promoters of the human HBA gene promoters. Sequenced as paired end fragments usinig Illumina GAII