title: Non-coding roX RNAs prevent the binding of the MSL-complex to heterochromatic regions.
abstract: Long non-coding RNAs contribute to dosage compensation in both mammals and Drosophila by inducing changes in the chromatin structure of the X-chromosome. In Drosophila melanogaster, roX1 and roX2 are long non-coding RNAs that together with proteins form the male-specific lethal (MSL) complex, which coats the entire male X-chromosome and mediates dosage compensation by increasing its transcriptional output. Studies on polytene chromosomes have demonstrated that when both roX1 and roX2 are absent, the MSL-complex becomes less abundant on the male X-chromosome and is relocated to the chromocenter and the 4th chromosome. Here we address the role of roX RNAs in MSL-complex targeting and the evolution of dosage compensation in Drosophila. We performed ChIP-seq experiments which showed that MSL-complex recruitment to high affinity sites (HAS) on the X-chromosome is independent of roX and that the HAS sequence motif is conserved in D. simulans. Additionally, a complete and enzymatically active MSL-complex is recruited to six specific genes on the 4th chromosome. Interestingly, our sequence analysis showed that in the absence of roX RNAs, the MSL-complex has an affinity for regions enriched in Hoppel transposable elements and repeats in general. We hypothesize that roX mutants reveal the ancient targeting of the MSL-complex and propose that the role of roX RNAs is to prevent the binding of the MSL-complex to heterochromatin.
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Margarida L A
authors.initials: ML
authors.lastname: Figueiredo
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Computational Life Science Cluster (CLiC), Umeå University, Umeå, Sweden.
authors.forename: Philge
authors.initials: P
authors.lastname: Philip
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Allgardsson
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden; Computational Life Science Cluster (CLiC), Umeå University, Umeå, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Stenberg
authors.affiliation: Department of Molecular Biology, Umeå University, Umeå, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Larsson
mesh_terms: D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D004303:Dosage Compensation, Genetic; D029721:Drosophila Proteins / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005260:Female; D006570:Heterochromatin / Q000378:metabolism*; D008297:Male; D009687:Nuclear Proteins / Q000502:physiology*; D059007:Polytene Chromosomes / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D022661:RNA, Untranslated; D012091:Repetitive Sequences, Nucleic Acid; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; D009687:Nuclear Proteins; D022661:RNA, Untranslated; D014157:Transcription Factors; C082132:msl-1 protein, Drosophila; C094166:msl-2 protein, Drosophila