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Fang Huang, Wei Shao, Koh Fujinaga, B Matija Peterlin
Autoimmune regulator (AIRE) and nu-clear factor-kappa B (NF-κB) are transcription factors (TFs) that direct the expression of individual genes and gene clusters. Bromodomain-containing protein 4 (BRD4) is an epigenetic regulator that recognizes and binds to acetylated histones. BRD4 also has been reported to promote interactions between the positive elongation factor b (P-TEFb) and AIRE or P-TEFb and NF-κB subunit p65. Here, we report that AIRE and p65 bind to P-TEFb independently of BRD4. JQ1, a compound that disrupts interactions between BRD4 and acetylated proteins, does not decrease transcriptional activities of AIRE or p65...
February 20, 2018: Journal of Biological Chemistry
Samantha B Shelton, Nakul M Shah, Nathan S Abell, Sravan K Devanathan, Marvin Mercado, Blerta Xhemalçe
RNAP II switching from the paused to the productive transcription elongation state is a pivotal regulatory step that requires specific phosphorylations catalyzed by the P-TEFb kinase. Nucleosolic P-TEFb activity is inhibited by its interaction with the ribonuclear protein complex built around the 7SK small nuclear RNA (7SK snRNP). MePCE is the RNA methyltransferase that methylates and stabilizes 7SK in the nucleosol. Here, we report that MePCE also binds chromatin through the histone H4 tail to serve as a P-TEFb activator at specific genes important for cellular identity...
February 6, 2018: Cell Reports
Gabriel Bidaux, Corentin Le Nézet, Mariano Gonzalez Pisfil, Mélanie Henry, Alessandro Furlan, Oliver Bensaude, Bernard Vandenbunder, Laurent Héliot
Biochemical studies have revealed that the RNA Polymerase II (RNAPII) pause release is triggered by phosphorylation of the transcription machinery by the positive transcription elongation factor b (P-TEFb). However, there are no direct report that P-TEFb and RNA polymerase II interact in single living cells and the biophysical mechanisms mediating this association are still unclear. Förster resonance energy transfer (FRET) detects molecular interactions at the subcellular level. Time domain fluorescence lifetime imaging provides an accurate quantification of FRET efficiency, EFRET, because it is fluorochrome concentration-independent and insensitive to fluorescence bleed-through...
February 6, 2018: Biophysical Journal
Liang Chen, Jia-Yu Chen, Yi-Jou Huang, Ying Gu, Jinsong Qiu, Hao Qian, Changwei Shao, Xuan Zhang, Jing Hu, Hairi Li, Shunmin He, Yu Zhou, Omar Abdel-Wahab, Dong-Er Zhang, Xiang-Dong Fu
Mutations in several general pre-mRNA splicing factors have been linked to myelodysplastic syndromes (MDSs) and solid tumors. These mutations have generally been assumed to cause disease by the resultant splicing defects, but different mutations appear to induce distinct splicing defects, raising the possibility that an alternative common mechanism is involved. Here we report a chain of events triggered by multiple splicing factor mutations, especially high-risk alleles in SRSF2 and U2AF1, including elevated R-loops, replication stress, and activation of the ataxia telangiectasia and Rad3-related protein (ATR)-Chk1 pathway...
February 1, 2018: Molecular Cell
Annemieke A Michels, Olivier Bensaude
Hexim1 acts as a tumor suppressor and is involved in the regulation of innate immunity. It was initially described as a non-coding RNA-dependent regulator of transcription. Here, we detail how 7SK RNA binds to Hexim1 and turns it into an inhibitor of the positive transcription elongation factor (P-TEFb). In addition to its action on P-TEFb, it plays a role in a variety of different mechanisms: it controls the stability of transcription factor components and assists binding of transcription factors to their targets...
January 18, 2018: Transcription
Enrico Ne, Robert-Jan Palstra, Tokameh Mahmoudi
In this review, we cover transcription regulation of human immunodeficiency virus type 1 (HIV-1) gene expression, focusing on the invaluable contributions, made by HIV research over the years, toward the field of transcription. In this context, the HIV promoter can be considered to be a well-studied model promoter, which although a viral promoter, is subject to the same cellular regulatory mechanisms that modulate the transcriptional control of endogenous host cellular genes. The molecular control of HIV-1 transcription has been well studied and considerable knowledge toward development of alternative strategies for therapies aimed at eradicating both active but also latent HIV-1 has been obtained...
2018: International Review of Cell and Molecular Biology
Samantha M Bevill, Jon S Zawistowski, Gary L Johnson
Kinase inhibitors targeting the mitogen/extracellular signal-regulated kinase kinase (MEK)- extracellular signal related kinase (ERK) signaling pathway have limited durability in inhibiting growth of triple-negative breast cancer. We defined genome wide enhancer remodeling following MEK inhibition capable of driving adaptive gene transcription. Targeting positive elongation factor (P-TEFb) transcriptional regulatory complex members can block enhancer remodeling making the response to MEK-ERK inhibition durable...
2017: Molecular & Cellular Oncology
Panpan Lu, Yinzhong Shen, He Yang, Yanan Wang, Zhengtao Jiang, Xinyi Yang, Yangcheng Zhong, Hanyu Pan, Jianqing Xu, Hongzhou Lu, Huanzhang Zhu
Persistent latent reservoir in resting CD4+ T cells is a major obstacle in curing HIV-1 infection. Effective strategies for eradication of the HIV-1 reservoir are urgently needed. We report here for the first time that two BET inhibitors, RVX-208, which has entered phase II clinical trials for diverse cardiovascular disorders, and PFI-1, which has been widely studied in oncology, can reactivate HIV-1 from latency. RVX-208 and PFI-1 treatment alone or in combination with other latency reversing agents efficiently reactivated HIV-1 transcription through an up-regulation of P-TEFb by increasing CDK9 Thr-186 phosphorylation in latently infected Jurkat T cells in vitro...
November 30, 2017: Scientific Reports
Zahra Bazi, Michele Bertacchi, Mozhgan Abasi, Samira Mohammadi-Yeganeh, Masoud Soleimani, Nicole Wagner, Hossein Ghanbarian
Rn7SK-mediated global transcriptional regulation, key function of this small nuclear RNA (snRNA), is mediated by inhibition of the positive transcription elongation factor b (P-TEFb). Recently, we have identified a potential anti-proliferative and tumor-suppressive function of Rn7SK. However, its possible regulatory role in development and cell programming has not been investigated so far. Here, we examined transcriptional levels of Rn7SK in different mouse organs. Interestingly, an increased expression level of the RNA was observed in the brain...
November 1, 2017: Journal of Cellular Biochemistry
Daniela Boehm, Melanie Ott
The main obstacle to eradicating HIV-1 from patients is post-integration latency (Finzi et al., 1999). Antiretroviral treatments target only actively replicating virus, while latent infections that have low or no transcriptional activity remain untreated (Sedaghat et al., 2007). To eliminate viral reservoirs, one strategy focuses on reversing HIV-1 latency via 'shock and kill' (Deeks, 2012). The basis of this strategy is to overcome the molecular mechanisms of HIV-1 latency by therapeutically inducing viral gene and protein expression under antiretroviral therapy and to cause selective cell death via the lytic properties of the virus, or the immune system now recognizing the infected cells...
June 5, 2017: Bio-protocol
Y-B Yang, X-L Wu, B Ke, Y-J Huang, S-Q Chen, Y-Q Su, J Qin
OBJECTIVE: To investigate the effect of caloric restriction (CR) on expressions of peroxisome proliferators-activated receptors (PPARs) and positive transcription elongation factor b (P-TEFb) (including cyclin-dependent kinase 9 (CDK9) and cyclin T1) protein in visceral adipose tissue of obese rats. MATERIALS AND METHODS: Obese rats were induced by high-fat diet for 8 weeks. Then they were divided into three groups: Model (n=5), 50% Calorie Restricted (50% CR, n=5), Intermittent Fasting (IF) (eight cycles of 3-d fasting and 3-d refeeding, n=6) for 8 weeks...
October 2017: European Review for Medical and Pharmacological Sciences
Sebastian Eilebrecht, Bernd-Joachim Benecke, Arndt G Benecke
The transactivating response element (TAR) structure of the nascent HIV-1 transcript is critically involved in the recruitment of inactive positive transcription elongation factor b (P-TEFb) to the promoter proximal paused RNA polymerase II. The viral transactivator Tat is responsible for subsequent P-TEFb activation in order to start efficient viral transcription elongation. In the absence of the viral transactivator of transcription (Tat), e.g., during latency or in early stages of HIV transcription, TAR mediates an interaction of P-TEFb with its inhibitor hexamethylene bis-acetamide-inducible protein 1 (HEXIM1), keeping P-TEFb in its inactive form...
October 2017: Genomics, Proteomics & Bioinformatics
Mark M Painter, Thomas D Zaikos, Kathleen L Collins
Human immunodeficiency virus type 1 (HIV-1) establishes transcriptionally silent latent infections in resting memory T cells and hematopoietic stem and progenitor cells (HSPCs), which allows the virus to persist in infected individuals despite antiretroviral therapy. Developing in vitro models of HIV-1 latency that recapitulate the characteristics of latently infected cells in vivo is crucial to identifying and developing effective latency-reversing therapies. HSPCs exist in a quiescent state in vivo , and quiescence is correlated with latent infections in T cells...
December 15, 2017: Journal of Virology
Saskia Gressel, Björn Schwalb, Tim Michael Decker, Weihua Qin, Heinrich Leonhardt, Dirk Eick, Patrick Cramer
Gene transcription can be activated by decreasing the duration of RNA polymerase II pausing in the promoter-proximal region, but how this is achieved remains unclear. Here we use a 'multi-omics' approach to demonstrate that the duration of polymerase pausing generally limits the productive frequency of transcription initiation in human cells ('pause-initiation limit'). We further engineer a human cell line to allow for specific and rapid inhibition of the P-TEFb kinase CDK9, which is implicated in polymerase pause release...
October 10, 2017: ELife
Eric B Gibbs, Tatiana N Laremore, Grace A Usher, Bede Portz, Erik C Cook, Scott A Showalter
The positive transcription elongation factor b (P-TEFb) promotes transcription elongation through phosphorylation of the RNA polymerase II C-terminal domain. This process is not well understood, partly due to difficulties in determining the specificity of P-TEFb toward the various heptad repeat motifs within the C-terminal domain. A simple assay using mass spectrometry was developed to identify the substrate specificity of the Drosophila melanogaster P-TEFb (DmP-TEFb) in vitro. This assay demonstrated that DmP-TEFb preferentially phosphorylates Ser5 and, surprisingly, that pre-phosphorylation or conserved amino acid variation at the 7-position in the heptad can alter DmP-TEFb specificity, leading to the creation of distinct double-phosphorylation marks...
November 7, 2017: Biophysical Journal
Chen-Chen Zhou, Qiu-Chan Xiong, Xin-Xing Zhu, Wen Du, Peng Deng, Xiao-Bing Li, Yi-Zhou Jiang, Shu-Juan Zou, Cun-Yu Wang, Quan Yuan
AFF1 and AFF4 belong to the AFF (AF4/FMR2) family of proteins, which function as scaffolding proteins linking two different transcription elongation factors, positive elongation factor b (P-TEFb) and ELL1/2, in super elongation complexes (SECs). Both AFF1 and AFF4 regulate gene transcription through elongation and chromatin remodeling. However, their function in the osteogenic differentiation of mesenchymal stem cells (MSCs) is unknown. In this study, we show that small interfering RNA (siRNA)-mediated depletion of AFF1 in human MSCs leads to increased alkaline phosphatase (ALP) activity, enhanced mineralization and upregulated expression of osteogenic-related genes...
2017: Bone Research
Yu Zhang, Liang Zhou, Yun Leng, Yun Dai, Robert Z Orlowski, Steven Grant
The role of the positive RNA Pol II regulator, P-TEFb (positive transcription elongation factor b), in maintenance of the anti-apoptotic protein Mcl-1 and bortezomib (btz) resistance was investigated in human multiple myeloma (MM) cells. Mcl-1 was up-regulated in all MM lines tested, including bortezomib-resistant lines, human MM xenograft mouse models, and primary CD138(+) MM cells. Mcl-1 over-expression significantly reduced bortezomib lethality, indicating a functional role for Mcl-1 in bortezomib resistance...
August 29, 2017: Oncotarget
Naoko Sakurai, Yuko Inamochi, Takuya Inoue, Natsuyo Hariya, Musashi Kawamura, Masami Yamada, Anup Dey, Akira Nishiyama, Takeo Kubota, Keiko Ozato, Toshinao Goda, Kazuki Mochizuki
We previously reported that induction of the adipocyte-specific gene adiponectin (Adipoq) during 3T3-L1 adipocyte differentiation is closely associated with epigenetic memory histone H3 acetylation on the transcribed region of the gene. We used 3T3-L1 adipocytes and Brd4 heterozygous mice to investigate whether the induction of Adipoq during adipocyte differentiation is regulated by histone acetylation and the binding protein bromodomain containing 4 (BRD4) on the transcribed region. Depletion of BRD4 by shRNA and inhibition by (+)-JQ1, an inhibitor of BET family proteins including BRD4, reduced Adipoq expression and lipid droplet accumulation in 3T3-L1 adipocytes...
September 20, 2017: Scientific Reports
Jun Wu, Ming-Tao Ao, Rui Shao, Hui-Ru Wang, Diao Yu, Mei-Juan Fang, Xiang Gao, Zhen Wu, Qiang Zhou, Yu-Hua Xue
The principal barrier to the eradication of HIV/AIDS is the existence of latent viral reservoirs. One strategy to overcome this barrier is to use latency-reversing agents (LRAs) to reactivate the latent proviruses, which can then be eliminated by effective anti-retroviral therapy. Although a number of LRAs have been found to reactivate latent HIV, they have not been used clinically due to high toxicity and poor efficacy. In this study, we report the identification of a chalcone analogue called Amt-87 that can significantly reactivate the transcription of latent HIV provirses and act synergistically with known LRAs such as prostratin and JQ1 to reverse latency...
September 6, 2017: Scientific Reports
Pengfei Wang, Panpan Lu, Xiying Qu, Yinzhong Shen, Hanxian Zeng, Xiaoli Zhu, Yuqi Zhu, Xian Li, Hao Wu, Jianqing Xu, Hongzhou Lu, Zhongjun Ma, Huanzhang Zhu
Cells harboring latent HIV-1 pose a major obstacle to eradication of the virus. The 'shock and kill' strategy has been broadly explored to purge the latent reservoir; however, none of the current latency-reversing agents (LRAs) can safely and effectively activate the latent virus in patients. In this study, we report an ingenol derivative called EK-16A, isolated from the traditional Chinese medicinal herb Euphorbia kansui, which displays great potential in reactivating latent HIV-1. A comparison of the doses used to measure the potency indicated EK-16A to be 200-fold more potent than prostratin in reactivating HIV-1 from latently infected cell lines...
August 25, 2017: Scientific Reports
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