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Descostes N.,Aix - Marseille University | Descostes N.,French National Center for Scientific Research | Descostes N.,French Institute of Health and Medical Research | Heidemann M.,Helmholtz Center Munich | And 22 more authors.

In mammals, the carboxy-terminal domain (CTD) of RNA polymerase (Pol) II consists of 52 conserved heptapeptide repeats containing the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Post-translational modifications of the CTD coordinate the transcription cycle and various steps of mRNA maturation. Here we describe Tyr1 phosphorylation (Tyr1P) as a hallmark of promoter (5' associated) Pol II in mammalian cells, in contrast to what was described in yeast. Tyr1P is predominantly found in antisense orientation at promoters but is also specifically enriched at active enhancers. Mutation of Tyr1 to phenylalanine (Y1F) prevents the formation of the hyper-phosphorylated Pol IIO form, induces degradation of Pol II to the truncated Pol IIB form and results in a lethal phenotype. Our results suggest that Tyr1P has evolved specialized and essential functions in higher eukaryotes associated with antisense promoter and enhancer transcription, and Pol II stability. Source

Lepoivre C.,Technological Advances for Genomics and Clinics TAGC | Lepoivre C.,Aix - Marseille University | Lepoivre C.,French Institute of Health and Medical Research | Belhocine M.,Technological Advances for Genomics and Clinics TAGC | And 51 more authors.
BMC Genomics

Background: Divergent transcription is a wide-spread phenomenon in mammals. For instance, short bidirectional transcripts are a hallmark of active promoters, while longer transcripts can be detected antisense from active genes in conditions where the RNA degradation machinery is inhibited. Moreover, many described long non-coding RNAs (lncRNAs) are transcribed antisense from coding gene promoters. However, the general significance of divergent lncRNA/mRNA gene pair transcription is still poorly understood. Here, we used strand-specific RNA-seq with high sequencing depth to thoroughly identify antisense transcripts from coding gene promoters in primary mouse tissues.Results: We found that a substantial fraction of coding-gene promoters sustain divergent transcription of long non-coding RNA (lncRNA)/mRNA gene pairs. Strikingly, upstream antisense transcription is significantly associated with genes related to transcriptional regulation and development. Their promoters share several characteristics with those of transcriptional developmental genes, including very large CpG islands, high degree of conservation and epigenetic regulation in ES cells. In-depth analysis revealed a unique GC skew profile at these promoter regions, while the associated coding genes were found to have large first exons, two genomic features that might enforce bidirectional transcription. Finally, genes associated with antisense transcription harbor specific H3K79me2 epigenetic marking and RNA polymerase II enrichment profiles linked to an intensified rate of early transcriptional elongation.Conclusions: We concluded that promoters of a class of transcription regulators are characterized by a specialized transcriptional control mechanism, which is directly coupled to relaxed bidirectional transcription. © 2013 Lepoivre et al.; licensee BioMed Central Ltd. Source

Forne I.,Biomedical Center Munich | Descostes N.,Center Dimmunologie Of Marseille Luminy | Maqbool M.A.,Institute of Molecular Genetics of Montpellier IGMM | Flatley A.,Institute of Molecular Immunology | And 5 more authors.

Dynamic modification of heptad-repeats with the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 of RNA polymerase II (RNAPII) C-terminal domain (CTD) regulates transcription-coupled processes. Mass spectrometry analysis revealed that K7-residues in non-consensus repeats of human RNAPII are modified by acetylation, or mono-, di-, and tri-methylation. K7ac, K7me2, and K7me3 were found exclusively associated with phosphorylated CTD peptides, while K7me1 occurred also in non-phosphorylated CTD. The monoclonal antibody 1F5 recognizes K7me1/2 residues in CTD and reacts with RNAPIIA. Treatment of cellular extracts with phosphatase or of cells with the kinase inhibitor flavopiridol unmasked the K7me1/2 epitope in RNAPII0, consistent with the association of K7me1/2 marks with phosphorylated CTD peptides. Genome-wide profiling revealed high levels of K7me1/2 marks at the transcriptional start site of genes for sense and antisense transcribing RNAPII. The new K7 modifications further expand the mammalian CTD code to allow regulation of differential gene expression. © 2015 The Author(s). Published with license by Taylor & Francis Group, LLC. Source

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