X chromosome dosage compensation via enhanced transcriptional elongation in Drosophila males (Untreated)

MSL (Male-specific lethal) complex increases transcription on the single X chromosome of Drosophila males in order to equalize expression of X-linked genes between males (XY) and females (XX). The increase in transcript levels correlates with MSL- dependent acetylation of histone H4 at K16 within the bodies of active genes, but identification of the transcriptional step affected has not been possible. In this study, we use global run-on sequencing (GRO-seq) to examine the specific effect of MSL complex on RNA Polymerase II (RNAP II) on a genome-wide level. Results indicate that MSL complex enhances transcription by facilitating the progression of RNAP II across the bodies of active X-linked genes. Improving transcriptional output downstream of typical gene-specific control may explain how dosage compensation can be imposed on the diverse set of genes along an entire chromosome. Overall design: Global Run-On Sequencing (GRO-Seq) reads, i.e., RNA-Seq of nascent RNA transcripts, from D. Melanogaster SL2 cells. Two biological replicates were analyzed.

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Kharchenko PV, Alekseyenko AA, Schwartz YB, Minoda A, Riddle NC, Ernst J, Sabo PJ, Larschan E, Gorchakov AA, Gu T, Linder-Basso D, Plachetka A, Shanower G, Tolstorukov MY, Luquette LJ, Xi R, Jung YL, Park RW, Bishop EP, Canfield TK, Sandstrom R, Thurman RE, MacAlpine DM, Stamatoyannopoulos JA, Kellis M, Elgin SC, Kuroda MI, Pirrotta V, Karpen GH, Park PJ