Project description: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.
Project description: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.
Project description:Mediator is a coregulatory complex involved in regulating the transcription of Pol II-dependent genes. Metazoan Mediator subunit MED26 functions as a docking site for the ELL/EAF-containing Super Elongation Complex (SEC) and L ittle Elongation Complex (LEC), which regulate the expression of distinct genes. MED26 helps to recruit SEC to protein-coding genes including c-Myc and LEC to small nuclear RNA (snRNA) genes. However, why MED26 takes advantage of SEC or LEC to regulate different claases of genes is unclear. Here, we present evidence that MED26 recruits LEC to support optimal transcription termination at non-polyadenylated genes including snRNA and replication-dependent histone (RDH) genes. Our findings indicate that LEC recruited by MED26 promotes efficient transcription termination by Pol II through interaction with CBC-ARS2 and NELF/DSIF, and then LEC promotes 3’-end processing through the recruitment of Integrator or Heat labile factor to snRNA or RDH genes, respectively.
Project description: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.
Project description: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. 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).
Project description:Eleven-nineteen lysine-rich leukemia (ELL) participates in the super elongation complex (SEC) with the RNA polymerase II (Pol II) CTD kinase P-TEFb. SEC is a key regulator in the expression of HOX genes in mixed lineage leukemia (MLL)-based hematological malignancies, in the control of induced gene expression early in development, and in immediate early gene transcription. Here, we identify 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 Pol II-transcribed small nuclear RNA (snRNA) genes, and the loss of LEC results in decreased snRNA expression in both flies and mammals. The specialization of the SEC and LEC complexes for mRNA and snRNA-containing genes, respectively, suggests the presence of specific classes of elongation factors for each class of genes transcribed by RNA polymerase II.
Project description:Kaposi sarcoma is the most common cancer in AIDS patients and is typified by red skin lesions.The disease is caused by the KSHV virus (HHV8) and is recognisable by its distinctive red skin lesions. The lesions are KSHV infected spindle cells expressing markers of the lymphatic endothelial and blood vessel endothelial cells as well as other cell types. The effects of KSHV infection of lymphatic endothelial cells (LEC) cultured in 3D matrix for three days were assayed using Affymetrix hgu133plus2 chips. There are n=3 of 1. control LEC spheroids (LEC), 2. KSHV infected LEC spheroids (K-LEC)
Project description:To investigate the mechanisms underlying the connection between LEC and cancer cells and their potential roles in tumorigenesis we co-cultured LEC and HaCa4 cells for 24 hours and compared the transcript levels of both FACS-isolated HaCa4 cells and LEC from co-cultures with those from individual cell cultures