Fukuoka T, Kawai A, Takahara T
… +4 more, Mori M, Roeder RG, Hasegawa N, Ito M
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· 2019 Jun · PMID 31135261
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Transcriptional activation by PML-RARα, an acute promyelocytic leukemia-related oncofusion protein, requires pharmacological concentrations of all-trans retinoic acid (ATRA). However, the mechanism by which the liganded...Transcriptional activation by PML-RARα, an acute promyelocytic leukemia-related oncofusion protein, requires pharmacological concentrations of all-trans retinoic acid (ATRA). However, the mechanism by which the liganded PML-RARα complex leads to the formation of the preinitiation complex has been unidentified. Here we demonstrate that the Mediator subunit MED1 plays an important role in the ATRA-dependent activation of the PML-RARα-bound promoter. Luciferase reporter assays showed that PML-RARα induced significant transcription at pharmacological doses (1 μM) of ATRA; however, this was submaximal and equivalent to the level of transcription driven by intact RARα at physiological doses (1 nM) of ATRA. Transcription depended upon the interaction of PML-RARα with the two LxxLL nuclear receptor recognition motifs of MED1, and LxxLL→LxxAA mutations led to minimal transcription. Mechanistically, MED1 interacted ATRA-dependently with the RARα portion of PML-RARα through the two LxxLL motifs of MED1. These results suggest that PML-RARα initiates ATRA-induced transcription through its interaction with MED1.
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· 2019 Jun · PMID 31057041
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In eukaryotes, divergent transcription is a major source of noncoding RNAs. Recent studies have uncovered that in yeast, the transcription factor Rap1 restricts transcription in the divergent direction and thereby contro...In eukaryotes, divergent transcription is a major source of noncoding RNAs. Recent studies have uncovered that in yeast, the transcription factor Rap1 restricts transcription in the divergent direction and thereby controls promoter directionality. Here, we summarize these findings, propose regulatory principles, and discuss the implications for eukaryotic gene regulation.
Zhang JG, Xu C, Zhang L
… +3 more, Zhu W, Shen H, Deng HW
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· 2019 Jun · PMID 30696368
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Gene transcription is regulated with distinct sets of regulatory factors at multiple levels. Transcriptional and post-transcriptional regulation constitute two major regulation modes of gene expression to either activate...Gene transcription is regulated with distinct sets of regulatory factors at multiple levels. Transcriptional and post-transcriptional regulation constitute two major regulation modes of gene expression to either activate or repress the initiation of transcription and thereby control the number of proteins synthesized during translation. Disruptions of the proper regulation patterns at transcriptional and post-transcriptional levels are increasingly recognized as causes of human diseases. Consequently, identifying the differential gene expression at transcriptional and post-transcriptional levels respectively is vital to identify potential disease-associated and/or causal genes and understand their roles in the disease development. Here, we proposed a novel method with a linear mixed model that can identify a set of differentially expressed genes at transcriptional and post-transcriptional levels. The simulation and real data analysis showed our method could provide an accurate way to identify genes subject to aberrant transcriptional and post-transcriptional regulation and reveal the potential causal genes that contributed to the diseases.
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· 2019 Jun · PMID 30663929
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We recently reported that the cyclin T1 histidine-rich domain creates a phase-separated environment to promote hyperphosphorylation of RNA polymerase II C-terminal domain and robust transcriptional elongation by P-TEFb....We recently reported that the cyclin T1 histidine-rich domain creates a phase-separated environment to promote hyperphosphorylation of RNA polymerase II C-terminal domain and robust transcriptional elongation by P-TEFb. Here, we discuss this and several other recent discoveries to demonstrate that phase separation is important for controlling various aspects of transcription.
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· 2019 Apr · PMID 30585107
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The Mediator-associated kinases CDK8 and CDK19 function in the context of three additional proteins: CCNC and MED12, which activate CDK8/CDK19 kinase function, and MED13, which enables their association with the Mediator...The Mediator-associated kinases CDK8 and CDK19 function in the context of three additional proteins: CCNC and MED12, which activate CDK8/CDK19 kinase function, and MED13, which enables their association with the Mediator complex. The Mediator kinases affect RNA polymerase II (pol II) transcription indirectly, through phosphorylation of transcription factors and by controlling Mediator structure and function. In this review, we discuss cellular roles of the Mediator kinases and mechanisms that enable their biological functions. We focus on sequence-specific, DNA-binding transcription factors and other Mediator kinase substrates, and how CDK8 or CDK19 may enable metabolic and transcriptional reprogramming through enhancers and chromatin looping. We also summarize Mediator kinase inhibitors and their therapeutic potential. Throughout, we note conserved and divergent functions between yeast and mammalian CDK8, and highlight many aspects of kinase module function that remain enigmatic, ranging from potential roles in pol II promoter-proximal pausing to liquid-liquid phase separation.
Hinkle ER, Wiedner HJ, Black AJ
… +1 more, Giudice J
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· 2019 Feb · PMID 30556762
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RNA processing encompasses the capping, cleavage, polyadenylation and alternative splicing of pre-mRNA. Proper muscle development relies on precise RNA processing, driven by the coordination between RNA-binding proteins....RNA processing encompasses the capping, cleavage, polyadenylation and alternative splicing of pre-mRNA. Proper muscle development relies on precise RNA processing, driven by the coordination between RNA-binding proteins. Recently, skeletal muscle biology has been intensely investigated in terms of RNA processing. High throughput studies paired with deletion of RNA-binding proteins have provided a high-level understanding of the molecular mechanisms controlling the regulation of RNA-processing in skeletal muscle. Furthermore, misregulation of RNA processing is implicated in muscle diseases. In this review, we comprehensively summarize recent studies in skeletal muscle that demonstrated: (i) the importance of RNA processing, (ii) the RNA-binding proteins that are involved, and (iii) diseases associated with defects in RNA processing.
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· 2019 Apr · PMID 30488763
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The transcription cycle of RNA polymerase II (Pol II) is regulated by a set of cyclin-dependent kinases (CDKs). Cdk7, associated with the transcription initiation factor TFIIH, is both an effector CDK that phosphorylates...The transcription cycle of RNA polymerase II (Pol II) is regulated by a set of cyclin-dependent kinases (CDKs). Cdk7, associated with the transcription initiation factor TFIIH, is both an effector CDK that phosphorylates Pol II and other targets within the transcriptional machinery, and a CDK-activating kinase (CAK) for at least one other essential CDK involved in transcription. Recent studies have illuminated Cdk7 functions that are executed throughout the Pol II transcription cycle, from promoter clearance and promoter-proximal pausing, to co-transcriptional chromatin modification in gene bodies, to mRNA 3´-end formation and termination. Cdk7 has also emerged as a target of small-molecule inhibitors that show promise in the treatment of cancer and inflammation. The challenges now are to identify the relevant targets of Cdk7 at each step of the transcription cycle, and to understand how heightened dependence on an essential CDK emerges in cancer, and might be exploited therapeutically.
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· 2019 Apr · PMID 30409083
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The fact that many cancer types display transcriptional addiction driven by dysregulation of oncogenic enhancers and transcription factors has led to increased interest in a group of protein kinases, known as transcripti...The fact that many cancer types display transcriptional addiction driven by dysregulation of oncogenic enhancers and transcription factors has led to increased interest in a group of protein kinases, known as transcriptional cyclin dependent kinases (tCDKs), as potential therapeutic targets. Despite early reservations about targeting a process that is essential to healthy cell types, there is now evidence that targeting tCDKs could provide enough therapeutic window to be effective in the clinic. Here, we discuss recent developments in this field, with an emphasis on highly-selective inhibitors and the challenges to be addressed before these inhibitors could be used for therapeutic purposes. Abbreviations: CAK: CDK-activating kinase;CDK: cyclin-dependent kinase;CMGC group: CDK-, MAPK-, GSK3-, and CLK-like;CTD: C-terminal repeat domain of the RPB1 subunit of RNA polymerase II;DRB: 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole;mCRPC: metastatic castration-resistant prostate cancer;NSCLC: non-small cell lung cancer;P-TEFb: positive elongation factor b;RNAPII: RNA polymerase II;S2: serine-2 of CTD repeats;S5: serine-5 of CTD repeats;S7: serine-7 of CTD repeats;SEC: super elongation complex;tCDK: transcriptional cyclin-dependent kinase;TNBC: triple-negative breast cancer.
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· 2019 Feb · PMID 30375921
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SAGA and NuA4 are coactivator complexes required for transcription on chromatin. Although they contain different enzymatic and biochemical activities, both contain the large Tra1 subunit. Recent electron microscopy studi...SAGA and NuA4 are coactivator complexes required for transcription on chromatin. Although they contain different enzymatic and biochemical activities, both contain the large Tra1 subunit. Recent electron microscopy studies have resolved the complete structure of Tra1 and its integration in SAGA/NuA4, providing important insight into Tra1 function.
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· 2019 Apr · PMID 30375919
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Studies of RNA Polymerase II (Pol II) transcription of the HIV-1 genome are of clinical interest, as the insight gained may lead to strategies to selectively reactivate latent viruses in patients in whom viral replicatio...Studies of RNA Polymerase II (Pol II) transcription of the HIV-1 genome are of clinical interest, as the insight gained may lead to strategies to selectively reactivate latent viruses in patients in whom viral replication is suppressed by antiviral drugs. Such a targeted reactivation may contribute to a functional cure of infection. This review discusses five Cyclin-dependent kinases - CDK7, CDK9, CDK11, CDK2, and CDK8 - involved in transcription and processing of HIV-1 RNA. CDK7 is required for Pol II promoter clearance of reactivated viruses; CDK7 also functions as an activating kinase for CDK9 when resting CD4 T cells harboring latent HIV-1 are activated. CDK9 is targeted by the viral Tat protein and is essential for productive Pol II elongation of the HIV-1 genome. CDK11 is associated with the TREX/THOC complex and it functions in the 3' end processing and polyadenylation of HIV-1 transcripts. CDK2 phosphorylates Tat and CDK9 and this stimulates Tat activation of Pol II transcription. CDK8 may stimulate Pol II transcription of the HIV-1 genome through co-recruitment with NF-κB to the viral promoter. Some notable open questions are discussed concerning the roles of these CDKs in HIV-1 replication and viral latency.
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· 2019 Apr · PMID 30319007
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As the new millennium began, CDK12 and CDK13 were discovered as nucleotide sequences that encode protein kinases related to cell cycle CDKs. By the end of the first decade both proteins had been qualified as CTD kinases,...As the new millennium began, CDK12 and CDK13 were discovered as nucleotide sequences that encode protein kinases related to cell cycle CDKs. By the end of the first decade both proteins had been qualified as CTD kinases, and it was emerging that both are heterodimers containing a Cyclin K subunit. Since then, many studies on CDK12 have shown that, through phosphorylating the CTD of transcribing RNAPII, it plays critical roles in several stages of gene expression, notably RNA processing; it is also crucial for maintaining genome stability. Fewer studies on CKD13 have clearly shown that it is functionally distinct from CDK12. CDK13 is important for proper expression of a number of genes, but it also probably plays yet-to-be-discovered roles in other processes. This review summarizes much of the work on CDK12 and CDK13 and attempts to evaluate the results and place them in context. Our understanding of these two enzymes has begun to mature, but we still have much to learn about both. An indicator of one major area of medically-relevant future research comes from the discovery that CDK12 is a tumor suppressor, notably for certain ovarian and prostate cancers. A challenge for the future is to understand CDK12 and CDK13 well enough to explain how their loss promotes cancer development and how we can intercede to prevent or treat those cancers. Abbreviations: CDK: cyclin-dependent kinase; CTD: C-terminal repeat domain of POLR2A; CTDK-I: CTD kinase I (yeast); Ctk1: catalytic subunit of CTDK-I; Ctk2: cyclin-like subunit of CTDK-I; PCAP: phosphoCTD-associating protein; POLR2A: largest subunit of RNAPII; SRI domain: Set2-RNAPII Interacting domain.
Fischer V, Schumacher K, Tora L
… +1 more, Devys D
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· 2019 Feb · PMID 30299209
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SAGA and TFIID are related transcription complexes, which were proposed to alternatively deliver TBP at different promoter classes. Recent genome-wide studies in yeast revealed that both complexes are required for the tr...SAGA and TFIID are related transcription complexes, which were proposed to alternatively deliver TBP at different promoter classes. Recent genome-wide studies in yeast revealed that both complexes are required for the transcription of a vast majority of genes by RNA polymerase II raising new questions about the role of coactivators.
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· 2019 Apr · PMID 30227759
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Cyclin-dependent kinase 9 (CDK9) is critical for RNA Polymerase II (Pol II) transcription initiation, elongation, and termination in several key biological processes including development, differentiation, and cell fate...Cyclin-dependent kinase 9 (CDK9) is critical for RNA Polymerase II (Pol II) transcription initiation, elongation, and termination in several key biological processes including development, differentiation, and cell fate responses. A broad range of diseases are characterized by CDK9 malfunction, illustrating its importance in maintaining transcriptional homeostasis in basal- and signal-regulated conditions. Here we provide a historical recount of CDK9 discovery and the current models suggesting CDK9 is a central hub necessary for proper execution of different steps in the transcription cycle. Finally, we discuss the current therapeutic strategies to treat CDK9 malfunction in several disease states. Abbreviations: CDK: Cyclin-dependent kinase; Pol II: RNA Polymerase II; PIC: Pre-initiation Complex; TFIIH: Transcription Factor-II H; snoRNA: small nucleolar RNA; CycT: CyclinT1/T2; P-TEFb: Positive Transcription Elongation Factor Complex; snRNP: small nuclear ribonucleo-protein; HEXIM: Hexamethylene Bis-acetamide-inducible Protein 1/2; LARP7: La-related Protein 7; MePCE: Methylphosphate Capping Enzyme; HIV: human immunodeficiency virus; TAT: trans-activator of transcription; TAR: Trans-activation response element; Hsp70: Heat Shock Protein 70; Hsp90/Cdc37: Hsp90- Hsp90 co-chaperone Cdc37; DSIF: DRB Sensitivity Inducing Factor; NELF: Negative Elongation Factor; CPSF: cleavage and polyadenylation-specific factor; CSTF: cleavage-stimulatory factor; eRNA: enhancer RNA; BRD4: Bromodomain-containing protein 4; JMJD6: Jumonji C-domain-containing protein 6; SEC: Super Elongation Complex; ELL: eleven-nineteen Lys-rich leukemia; ENL: eleven-nineteen leukemia; MLL: mixed lineage leukemia; BEC: BRD4-containing Elongation Complex; SEC-L2/L3: SEC-like complexes; KAP1: Kruppel-associated box-protein 1; KEC: KAP1-7SK Elongation Complex; DRB: Dichloro-1-ß-D-Ribofuranosylbenzimidazole; H2Bub1: H2B mono-ubiquitination; KM: KM05382; PP1: Protein Phosphatase 1; CDK9i: CDK9 inhibitor; SHAPE: Selective 2'-hydroxyl acylation analyzed by primer extension; TE: Typical enhancer; SE : Super enhancer.
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· 2019 Feb · PMID 30205741
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CHARGE syndrome is characterized by co-occurrence of multiple malformations due to abnormal development of neural crest cells. Here, we review the phenotypic and molecular overlap between CHARGE syndrome and similar path...CHARGE syndrome is characterized by co-occurrence of multiple malformations due to abnormal development of neural crest cells. Here, we review the phenotypic and molecular overlap between CHARGE syndrome and similar pathologies, and further discuss the observation that neural crest cells appear especially sensitive to malfunction of the chromatin-transcription-splicing molecular hub.
Frameshifting errors are common and mRNA quality control pathways, such as nonsense-mediated decay (NMD), exist to degrade these aberrant transcripts. Recent work has shown the existence of a genetic link between NMD and...Frameshifting errors are common and mRNA quality control pathways, such as nonsense-mediated decay (NMD), exist to degrade these aberrant transcripts. Recent work has shown the existence of a genetic link between NMD and codon-usage mediated mRNA decay. Here we present computational evidence that these pathways are synergic for removing frameshifts.
The ribosomal RNA genes (rDNA) of Drosophila melanogaster reside within centromere-proximal nucleolar organizers on both the X and Y chromosomes. Each locus contains between 200-300 tandem repeat rDNA units that encode 1...The ribosomal RNA genes (rDNA) of Drosophila melanogaster reside within centromere-proximal nucleolar organizers on both the X and Y chromosomes. Each locus contains between 200-300 tandem repeat rDNA units that encode 18S, 5.8S, 2S, and 28S ribosomal RNAs (rRNAs) necessary for ribosome biogenesis. In arthropods like Drosophila, about 60% of the rDNA genes have R1 and/or R2 retrotransposons inserted at specific sites within their 28S regions; these units likely fail to produce functional 28S rRNA. We showed earlier that R2 expression increases upon nucleolar stress caused by the loss of the ribosome assembly factor, Nucleolar Phosphoprotein of 140 kDa (Nopp140). Here we show that R1 expression is selectively induced by heat shock. Actinomycin D, but not α-amanitin, blocked R1 expression in S2 cells upon heat shock, indicating that R1 elements are transcribed by Pol I. A series of RT-PCRs established read-through transcription by Pol I from the 28S gene region into R1. Sequencing the RT-PCR products confirmed the 28S-R1 RNA junction and the expression of R1 elements within nucleolar rDNA rather than R1 elements known to reside in centromeric heterochromatin. Using a genome-wide precision run-on sequencing (PRO-seq) data set available at NCBI-GEO, we show that Pol I activity on R1 elements is negligible under normal non-heat shock conditions but increases upon heat shock. We propose that prior to heat shock Pol I pauses within the 5' end of R1 where we find a consensus "pause button", and that heat shock releases Pol I for read-through transcription farther into R1.
Every transcription cycle ends in termination when RNA polymerase dissociates from the DNA. Although conceptually simple, the mechanism has proven somewhat elusive in eukaryotic systems. Gene-editing and high resolution...Every transcription cycle ends in termination when RNA polymerase dissociates from the DNA. Although conceptually simple, the mechanism has proven somewhat elusive in eukaryotic systems. Gene-editing and high resolution polymerase mapping now offer clarification of important steps preceding transcriptional termination by RNA polymerase II in human cells.
It was recently shown that removal of GreA, a transcription fidelity factor, enhances DNA break repair. This counterintuitive result, arising from unresolved backtracked RNA polymerase impeding DNA resection and thereby...It was recently shown that removal of GreA, a transcription fidelity factor, enhances DNA break repair. This counterintuitive result, arising from unresolved backtracked RNA polymerase impeding DNA resection and thereby facilitating RecA-loading, leads to an interesting corollary: error-free full-length transcripts and broken chromosomes. Therefore, transcription fidelity may compromise genomic integrity.
High-speed single-molecule fluorescence microscopy in vivo shows that transcription factors in eukaryotes can act in oligomeric clusters mediated by molecular crowding and intrinsically disordered protein. This finding i...High-speed single-molecule fluorescence microscopy in vivo shows that transcription factors in eukaryotes can act in oligomeric clusters mediated by molecular crowding and intrinsically disordered protein. This finding impacts on the longstanding puzzle of how transcription factors find their gene targets so efficiently in the complex, heterogeneous environment of the cell. Abbreviations CDF - cumulative distribution function; FRAP - fluorescence recovery after photobleaching; GFP - Green fluorescent protein; STORM - stochastic optical reconstruction microscopy; TF - Transcription factor; YFP - Yellow fluorescent protein.