The little elongation complex (LEC) regulates small nuclear RNA transcription

The Eleven-nineteen Lysine-rich Leukemia (ELL)-containing Super Elongation Complex (SEC) containing P-TEFb is a key regulator in the expression of HOX genes in Mixed Lineage Leukemia (MLL)-based leukemia. We have identified an SEC-like complex in Drosophila, as well as a distinct ELL-containing complex that lacks P-TEFb and other components of SEC named the "little elongation complex" (LEC). LEC subunits are highly enriched at RNA Polymerase II (Pol II) transcribed small nuclear RNA (snRNA) genes and the loss of LEC results in decreased snRNA expression in both flies and mammals. The discovery of specificity of SEC and LEC complexes for mRNA and snRNA containing genes, respectively, suggest the presence of specific classes of elongation factors for each class of genes transcribed by RNA polymerase II. Examination of genome-wide binding profiles for ELL, Ice1, Lilli, and Pol II in D. melanogaster and by ChIP-seq. Identification of differentially expressed genes in ELL-RNAi and Ice1-RNAi in D. melanogaster by RNA-seq. Examination of genome-wide binding profiles for ELL in M. musculus. Identification of differentially expressed genes in ELL-RNAi in M. musculus by RNA-seq.