Multiple roles for LEC in initiation and elongation phases of snRNA gene transcription. Multiple roles for LEC in initiation and elongation phases of snRNA gene transcription

The small nuclear RNA (snRNA) genes have been widely used as a model system for understanding transcriptional regulation due to unique aspects of their promoter structure, selectivity for either RNA Polymerase (Pol) II or III and a unique mechanism of termination that is tightly linked with the promoter. Recently, we identified the Little Elongation Complex (LEC) in Drosophila that is required for the expression of Pol II-transcribed snRNA genes. Here, we identify the molecular mechanism by which LEC specifically regulates Pol II-dependent snRNA gene transcription. We present genetic and molecular evidence from both Drosophila and mammals that LEC regulates both initiation and elongation stages of transcription of Pol II-transcribed snRNA genes. Overall design: In human HCT116 cells we performed: ChIP-seq of ICE1, ICE2, ZC3H8, ELL, and AFF4; total RNA-seq following ICE1 knock-down and non-targeting (GFP) knock-down; ChIP-seq of ICE1 and Pol II following non-targetting (shGFP) and ICE1 knock-down (shICE1). In fly S2 cells we performed: Ice1 ChIP-seq following small hairpin knock-down of GFP (shGFP/non-targeting control) and Ice1 (knock-down of Ice1); ChIP-seq of Pol II following small hairpin knock-down of GFP (shGFP/non-targeting control), Ice1 (knock-down of Ice1), and Ell (knock-down of Ell).