Controlling the elongation phase of transcription with P-TEFb. 7SK small nuclear RNA binds to and inhibits the activity of CDK9/cyclin T complexes. The non-coding snRNA 7SK controls transcriptional termination, poising, and bidirectionality in embryonic stem cells. Transcription factors mediate the enzymatic disassembly of promoter-bound 7SK snRNP to locally recruit P-TEFb for transcription elongation. SR proteins collaborate with 7SK and promoter-associated nascent RNA to release paused polymerase. The 7SK small nuclear RNA inhibits the CDK9/cyclin T1 kinase to control transcription. A new method for detecting sites of 2′-O-methylation in RNA molecules. Processing of the precursors to small nucleolar RNAs and rRNAs requires common components. Box C/D snoRNA-associated proteins: two pairs of evolutionarily ancient proteins and possible links to replication and transcription. Fibrillarin binds directly and specifically to U16 box C/D snoRNA. & Ares, M., Jr Depletion of U3 small nucleolar RNA inhibits cleavage in the 5′ external transcribed spacer of yeast pre-ribosomal RNA and impairs formation of 18S ribosomal RNA. Small nucleolar RNAs and RNA-guided post-transcriptional modification. Direct competition between hnRNP C and U2AF65 protects the transcriptome from the exonization of Alu elements. iCLIP: Protein-RNA interactions at nucleotide resolution. Anticancer activity of CX-3543: a direct inhibitor of rRNA biogenesis. Effects of cytotoxic drugs on translocation of nucleolar RNA helicase RH-II/Gu. RNA-unwinding and RNA-folding activities of RNA helicase II/Gu–two activities in separate domains of the same protein. Flavopiridol inactivates P-TEFb and blocks most RNA polymerase II transcription in vivo. Flavopiridol inhibits P-TEFb and blocks HIV-1 replication. Eukaryotic snoRNAs: a paradigm for gene expression flexibility. Interaction of nucleolin with ribosomal RNA genes and its role in RNA polymerase I transcription. Integrative genomic analysis of human ribosomal DNA. E., Saiakhova, A., Manaenkov, P., Adams, M. The DEXD/H-box RNA helicase RHII/Gu is a co-factor for c-Jun-activated transcription. Down-regulation of RNA helicase II/Gu results in the depletion of 18 and 28 S rRNAs in Xenopus oocyte. Silencing of RNA helicase II/Guα inhibits mammalian ribosomal RNA production. DEAD-box helicases as integrators of RNA, nucleotide and protein binding. Toward a molecular understanding of RNA remodeling by DEAD-box proteins. DEAD-box proteins: the driving forces behind RNA metabolism. Our results uncover the multifaceted role of DDX21 in multiple steps of ribosome biogenesis, and provide evidence implicating a mammalian RNA helicase in RNA modification and Pol II elongation control. Promoter-bound DDX21 facilitates the release of the positive transcription elongation factor b (P-TEFb) from the 7SK snRNP in a manner that is dependent on its helicase activity, thereby promoting transcription of its target genes. In the nucleoplasm, DDX21 binds 7SK RNA and, as a component of the 7SK small nuclear ribonucleoprotein (snRNP) complex, is recruited to the promoters of Pol II-transcribed genes encoding ribosomal proteins and snoRNAs. In the nucleolus, DDX21 occupies the transcribed rDNA locus, directly contacts both rRNA and snoRNAs, and promotes rRNA transcription, processing and modification. Although broad, these molecular interactions, both at the chromatin and RNA level, exhibit remarkable specificity for the regulation of ribosomal genes. We demonstrate that DDX21 widely associates with Pol I- and Pol II-transcribed genes and with diverse species of RNA, most prominently with non-coding RNAs involved in the formation of ribonucleoprotein complexes, including ribosomal RNA, small nucleolar RNAs (snoRNAs) and 7SK RNA. Here we show that the DEAD-box RNA helicase DDX21 can sense the transcriptional status of both RNA polymerase (Pol) I and II to control multiple steps of ribosome biogenesis in human cells. DEAD-box RNA helicases are vital for the regulation of various aspects of the RNA life cycle 1, but the molecular underpinnings of their involvement, particularly in mammalian cells, remain poorly understood.
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