1
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Griffin KN, Walters BW, Li H, Wang H, Biancon G, Tebaldi T, Kaya CB, Kanyo J, Lam TT, Cox AL, Halene S, Chung JJ, Lesch BJ. Widespread association of the Argonaute protein AGO2 with meiotic chromatin suggests a distinct nuclear function in mammalian male reproduction. Genome Res 2022; 32:1655-1668. [PMID: 36109149 PMCID: PMC9528986 DOI: 10.1101/gr.276578.122] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/21/2022] [Indexed: 11/25/2022]
Abstract
Argonaute 2 (AGO2) is a ubiquitously expressed protein critical for regulation of mRNA translation and vital to animal development. AGO2 protein is found in both cytoplasmic and nuclear compartments, and although its cytoplasmic role is well studied, the biological relevance of nuclear AGO2 is unclear. Here, we address this problem in vivo using spermatogenic cells as a model. We find that AGO2 transiently binds both chromatin and nucleus-specific mRNA transcripts of hundreds of genes required for sperm production during male meiosis in mice, and that germline conditional knockout (cKO) of Ago2 causes depletion of the encoded proteins. Correspondingly, Ago2 cKO males show abnormal sperm head morphology and reduced sperm count, along with reduced postnatal viability of offspring. Together, our data reveal an unexpected nuclear role for AGO2 in enhancing expression of developmentally important genes during mammalian male reproduction.
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Affiliation(s)
- Kimberly N Griffin
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | | | - Haixin Li
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Huafeng Wang
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Giulia Biancon
- Section of Hematology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Comprehensive Cancer Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Toma Tebaldi
- Section of Hematology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Comprehensive Cancer Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123 Trento, Italy
| | - Carolyn B Kaya
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Jean Kanyo
- Keck MS & Proteomics Resource, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - TuKiet T Lam
- Keck MS & Proteomics Resource, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
| | - Andy L Cox
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Stephanie Halene
- Section of Hematology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Comprehensive Cancer Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Stem Cell Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Center for RNA Science and Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Department of Pathology, Gynecology & Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Jean-Ju Chung
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Bluma J Lesch
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Yale Comprehensive Cancer Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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2
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Nazer E, Gómez Acuña L, Kornblihtt AR. Seeking the truth behind the myth: Argonaute tales from "nuclearland". Mol Cell 2021; 82:503-513. [PMID: 34856122 DOI: 10.1016/j.molcel.2021.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/19/2022]
Abstract
Argonaute proteins have been traditionally characterized as a highly evolutionary conserved family engaged in post-transcriptional gene silencing pathways. The Argonaute family is mainly grouped into the AGO and PIWI clades. The canonical role of Argonaute proteins relies on their ability to bind small-RNAs that recognize complementary sequences on target mRNAs to induce either mRNA degradation or translational repression. However, there is an increasing amount of evidence supporting that Argonaute proteins also exert multiple nuclear functions that subsequently regulate gene expression. In this line, genome-wide studies showed that members from the AGO clade regulate transcription, 3D chromatin organization, and splicing of active loci located within euchromatin. Here, we discuss recent work based on high-throughput technologies that have significantly contributed to shed light on the multivariate nuclear functions of AGO proteins in different model organisms. We also analyze data supporting that AGO proteins are able to execute these nuclear functions independently from small RNA pathways. Finally, we integrate these mechanistic insights with recent reports highlighting the clinical importance of AGO in breast and prostate cancer development.
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Affiliation(s)
- Ezequiel Nazer
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular and CONICET-UBA, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina.
| | - Luciana Gómez Acuña
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | - Alberto R Kornblihtt
- Universidad de Buenos Aires (UBA), Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular and CONICET-UBA, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Buenos Aires, Argentina
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3
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Torres AG, Martí E. Toward an Understanding of Extracellular tRNA Biology. Front Mol Biosci 2021; 8:662620. [PMID: 33937338 PMCID: PMC8082309 DOI: 10.3389/fmolb.2021.662620] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/22/2021] [Indexed: 12/18/2022] Open
Abstract
Extracellular RNAs (exRNAs) including abundant full length tRNAs and tRNA fragments (tRFs) have recently garnered attention as a promising source of biomarkers and a novel mediator in cell-to-cell communication in eukaryotes. Depending on the physiological state of cells, tRNAs/tRFs are released to the extracellular space either contained in extracellular vesicles (EVs) or free, through a mechanism that is largely unknown. In this perspective article, we propose that extracellular tRNAs (ex-tRNAs) and/or extracellular tRFs (ex-tRFs) are relevant paracrine signaling molecules whose activity depends on the mechanisms of release by source cells and capture by recipient cells. We speculate on how ex-tRNA/ex-tRFs orchestrate the effects in target cells, depending on the type of sequence and the mechanisms of uptake. We further propose that tRNA modifications may be playing important roles in ex-tRNA biology.
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Affiliation(s)
- Adrian Gabriel Torres
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Eulàlia Martí
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigación Biomédica en Red sobre Epidemiología y Salud Pública, Madrid, Spain
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4
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Fernandes De Abreu DA, Salinas-Giegé T, Drouard L, Remy JJ. Alanine tRNAs Translate Environment Into Behavior in Caenorhabditis elegans. Front Cell Dev Biol 2020; 8:571359. [PMID: 33195203 PMCID: PMC7662486 DOI: 10.3389/fcell.2020.571359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/12/2020] [Indexed: 12/16/2022] Open
Abstract
Caenorhabditis elegans nematodes produce and maintain imprints of attractive chemosensory cues to which they are exposed early in life. Early odor-exposure increases adult chemo-attraction to the same cues. Imprinting is transiently or stably inherited, depending on the number of exposed generations. We show here that the Alanine tRNA (UGC) plays a central role in regulating C. elegans chemo-attraction. Naive worms fed on tRNAAla (UGC) purified from odor-experienced worms, acquire odor-specific imprints. Chemo-attractive responses require the tRNA-modifying Elongator complex sub-units 1 (elpc-1) and 3 (elpc-3) genes. elpc-3 deletions impair chemo-attraction, which is fully restored by wild-type tRNAAla (UGC) feeding. A stably inherited decrease of odor-specific responses ensues from early odor-exposition of elpc-1 deletion mutants. tRNAAla (UGC) may adopt various chemical forms to mediate the cross-talk between innately-programmed and environment-directed chemo-attractive behavior.
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Affiliation(s)
- Diana Andrea Fernandes De Abreu
- Genes, Environment, Plasticity, Institut Sophia Agrobiotech ISA UMR CNRS 7254, INRAE 1355, Université Nice Côte d’Azur, Sophia-Antipolis, France
| | - Thalia Salinas-Giegé
- Institut de Biologie Moléculaire des Plantes-CNRS, Université de Strasbourg, Strasbourg, France
| | - Laurence Drouard
- Institut de Biologie Moléculaire des Plantes-CNRS, Université de Strasbourg, Strasbourg, France
| | - Jean-Jacques Remy
- Genes, Environment, Plasticity, Institut Sophia Agrobiotech ISA UMR CNRS 7254, INRAE 1355, Université Nice Côte d’Azur, Sophia-Antipolis, France
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5
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MAF1 is a chronic repressor of RNA polymerase III transcription in the mouse. Sci Rep 2020; 10:11956. [PMID: 32686713 PMCID: PMC7371695 DOI: 10.1038/s41598-020-68665-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 06/11/2020] [Indexed: 01/09/2023] Open
Abstract
Maf1−/− mice are lean, obesity-resistant and metabolically inefficient. Their increased energy expenditure is thought to be driven by a futile RNA cycle that reprograms metabolism to meet an increased demand for nucleotides stemming from the deregulation of RNA polymerase (pol) III transcription. Metabolic changes consistent with this model have been reported in both fasted and refed mice, however the impact of the fasting-refeeding-cycle on pol III function has not been examined. Here we show that changes in pol III occupancy in the liver of fasted versus refed wild-type mice are largely confined to low and intermediate occupancy genes; high occupancy genes are unchanged. However, in Maf1−/− mice, pol III occupancy of the vast majority of active loci in liver and the levels of specific precursor tRNAs in this tissue and other organs are higher than wild-type in both fasted and refed conditions. Thus, MAF1 functions as a chronic repressor of active pol III loci and can modulate transcription under different conditions. Our findings support the futile RNA cycle hypothesis, elaborate the mechanism of pol III repression by MAF1 and demonstrate a modest effect of MAF1 on global translation via reduced mRNA levels and translation efficiencies for several ribosomal proteins.
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6
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Zaytseva O, Mitchell NC, Guo L, Marshall OJ, Parsons LM, Hannan RD, Levens DL, Quinn LM. Transcriptional repression of Myc underlies the tumour suppressor function of AGO1 in Drosophila. Development 2020; 147:147/11/dev190231. [PMID: 32527935 PMCID: PMC7295588 DOI: 10.1242/dev.190231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 04/27/2020] [Indexed: 12/29/2022]
Abstract
Here, we report novel tumour suppressor activity for the Drosophila Argonaute family RNA-binding protein AGO1, a component of the miRNA-dependent RNA-induced silencing complex (RISC). The mechanism for growth inhibition does not, however, involve canonical roles as part of the RISC; rather, AGO1 controls cell and tissue growth by functioning as a direct transcriptional repressor of the master regulator of growth, Myc. AGO1 depletion in wing imaginal discs drives a significant increase in ribosome biogenesis, nucleolar expansion and cell growth in a manner dependent on Myc abundance. Moreover, increased Myc promoter activity and elevated Myc mRNA in AGO1-depleted animals requires RNA polymerase II transcription. Further support for transcriptional AGO1 functions is provided by physical interaction with the RNA polymerase II transcriptional machinery (chromatin remodelling factors and Mediator Complex), punctate nuclear localisation in euchromatic regions and overlap with Polycomb Group transcriptional silencing loci. Moreover, significant AGO1 enrichment is observed on the Myc promoter and AGO1 interacts with the Myc transcriptional activator Psi. Together, our data show that Drosophila AGO1 functions outside of the RISC to repress Myc transcription and inhibit developmental cell and tissue growth. This article has an associated ‘The people behind the papers’ interview. Highlighted Article: In the Drosophila wing, the Argonaute family protein AGO1 acts independently of the miRNA-silencing pathway to restrict tissue growth by directly repressing transcription of the master growth regulator Myc.
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Affiliation(s)
- Olga Zaytseva
- Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia
| | - Naomi C Mitchell
- Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia
| | - Linna Guo
- Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia
| | | | | | - Ross D Hannan
- Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia
| | - David L Levens
- Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Leonie M Quinn
- Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia
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7
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Fawzy MS, Toraih EA, Alelwani W, Kattan SW, Alnajeebi AM, Hassan R. The prognostic value of microRNA-biogenesis genes Argonaute 1 and 2 variants in breast cancer patients. Am J Transl Res 2020; 12:1994-2006. [PMID: 32509194 PMCID: PMC7270005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 04/18/2020] [Indexed: 06/11/2023]
Abstract
MicroRNA machinery genes Argonaute 1 (AGO1) and 2 (AGO2) are associated with several hallmarks of cancer. They play a key role in transcriptomic silencing, regulation of the immune system, cell differentiation, and angiogenesis processes. The present pilot study aims to explore the impact of genetic variants rs636832 and rs2977490 of AGO1 and AGO2, respectively, on breast cancer (BC) risk in a sample of Mediterranean population. TaqMan genotyping assay of 93 consecutive breast cancer female patients and age- as well as ethnicity-matched controls, was done by Real-Time allele discrimination polymerase chain reaction. Association with the available clinical, histopathological and immunohistochemistry assessments was applied. In silico data analysis was also executed. Although allele and genotype frequencies distribution of both study variants were comparable in BC and healthy control cohorts, AGO1*G variant conferred a significant BC risk under recessive model [adjusted odds ratio (95% confidence interval); 4.90 (1.03-23.39), P = 0.024], and was significantly associated with lymph node infiltration (P = 0.037), distant metastasis (P = 0.019), advanced clinical stage (P < 0.001), recurrence (P = 0.032), and shorter overall survival (P = 0.001). Furthermore, AGO2*G/G genotype showed an association with poor pathological grade (P = 0.029). Our results suggested for the first time that rs636832 and rs2977490 variants of the miRNA-machinery genes AGO1 and 2, respectively, may impact susceptibility and/or clinical outcomes of BC patients in the study population.
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Affiliation(s)
- Manal S Fawzy
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Suez Canal UniversityIsmailia, Egypt
- Department of Biochemistry, Faculty of Medicine, Northern Border UniversityArar, Saudi Arabia
| | - Eman A Toraih
- Department of Surgery, Tulane University, School of MedicineNew Orleans, Louisiana, USA
- Genetics Unit, Department of Histology and Cell Biology, Faculty of Medicine, Suez Canal UniversityIsmailia, Egypt
| | - Walla Alelwani
- Department of Biochemistry, College of Science, University of JeddahJeddah, Saudi Arabia
| | - Shahad W Kattan
- Department of Medical Laboratory, College of Applied Medical Sciences, Taibah UniversityYanbu, Saudi Arabia
| | - Afnan M Alnajeebi
- Department of Biochemistry, College of Science, University of JeddahJeddah, Saudi Arabia
| | - Ranya Hassan
- Department of Clinical Pathology, Faculty of Medicine, Suez Canal UniversityIsmailia, Egypt
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8
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Argonaute2 attenuates active transcription by limiting RNA Polymerase II elongation in Drosophila melanogaster. Sci Rep 2018; 8:15685. [PMID: 30356106 PMCID: PMC6200757 DOI: 10.1038/s41598-018-34115-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/08/2018] [Indexed: 12/21/2022] Open
Abstract
Increasing lines of evidence support that Argonaute2 (AGO2) harbors several nuclear functions in metazoa. In particular, Drosophila AGO2 modulates transcription of developmentally regulated genes; however, the molecular mechanisms behind AGO2 recruitment into chromatin and its function in transcription have not been deeply explored. In this study, we show that Drosophila AGO2 chromatin association depends on active transcription. In order to gain insight into how AGO2 controls transcription, we performed differential ChIP-seq analysis for RNA Polymerase II (Pol II) upon depletion of AGO2. Remarkably, we find specific accumulation of the elongating but not initiating form of Pol II after AGO2 knockdown, suggesting that AGO2 impairs transcription elongation. Finally, AGO2 also affects Negative Elongation Factor (NELF) chromatin association but not the Cyclin Dependent Kinase 9 (CDK9). Altogether, these results provide key insights into the molecular role of AGO2 in attenuating elongation of certain actively transcribed genes.
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9
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Pong SK, Gullerova M. Noncanonical functions of microRNA pathway enzymes - Drosha, DGCR8, Dicer and Ago proteins. FEBS Lett 2018; 592:2973-2986. [PMID: 30025156 DOI: 10.1002/1873-3468.13196] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 07/10/2018] [Accepted: 07/12/2018] [Indexed: 01/15/2023]
Abstract
MicroRNAs (miRNAs) are small regulatory noncoding RNAs that are generated in the canonical RNA interference (RNAi) pathway. Drosha, DiGeorge syndrome critical region 8 (DGCR8) and Dicer are key players in miRNA biogenesis. Argonaute (Ago) proteins bind to miRNAs and are guided by them to find messenger RNA targets and carry out post-transcriptional silencing of protein-coding genes. Recently, emerging evidence suggests that RNAi factors have a range of noncanonical functions that are beyond miRNA biogenesis. These functions pertain to various biological processes, such as development, transcriptional regulation, RNA processing and maintenance of genome integrity. Here, we review recent literature reporting miRNA-independent, noncanonical functions of Drosha, DGCR8, Dicer and Ago proteins and discuss the importance of these functions.
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Affiliation(s)
- Sheng K Pong
- Sir William Dunn School of Pathology, University of Oxford, UK
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10
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Chen CY, Lanz RB, Walkey CJ, Chang WH, Lu W, Johnson DL. Maf1 and Repression of RNA Polymerase III-Mediated Transcription Drive Adipocyte Differentiation. Cell Rep 2018; 24:1852-1864. [PMID: 30110641 PMCID: PMC6138453 DOI: 10.1016/j.celrep.2018.07.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/05/2018] [Accepted: 07/12/2018] [Indexed: 12/11/2022] Open
Abstract
RNA polymerase (pol) III transcribes a variety of small untranslated RNAs involved in transcription, RNA processing, and translation. RNA pol III and its components are altered in various human developmental disorders, yet their roles in cell fate determination and development are poorly understood. Here we demonstrate that Maf1, a transcriptional repressor, promotes induction of mouse embryonic stem cells (mESCs) into mesoderm. Reduced Maf1 expression in mESCs and preadipocytes impairs adipogenesis, while ectopic Maf1 expression in Maf1-deficient cells enhances differentiation. RNA pol III repression by chemical inhibition or knockdown of Brf1 promotes adipogenesis. Altered RNA pol III-dependent transcription produces select changes in mRNAs with a significant enrichment of adipogenic gene signatures. Furthermore, RNA pol III-mediated transcription positively regulates long non-coding RNA H19 and Wnt6 expression, established adipogenesis inhibitors. Together, these studies reveal an important and unexpected function for RNA pol III-mediated transcription and Maf1 in mesoderm induction and adipocyte differentiation.
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Affiliation(s)
- Chun-Yuan Chen
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA, USA; Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Rainer B Lanz
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Christopher J Walkey
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Wen-Hsuan Chang
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Wange Lu
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA, USA; Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Deborah L Johnson
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.
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11
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Burke JM, Kincaid RP, Nottingham RM, Lambowitz AM, Sullivan CS. DUSP11 activity on triphosphorylated transcripts promotes Argonaute association with noncanonical viral microRNAs and regulates steady-state levels of cellular noncoding RNAs. Genes Dev 2017; 30:2076-2092. [PMID: 27798849 PMCID: PMC5066614 DOI: 10.1101/gad.282616.116] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/02/2016] [Indexed: 12/22/2022]
Abstract
Here, Burke et al. delineate a new pathway for mammalian small RNAs to enter the RNAi gene silencing machinery. They show that DUSP11 directly dephosphorylates viral triphosphate ncRNA transcripts and that this is required for efficient silencing by RISC, suggesting that mammalian viral pathogens can use DUSP11 to generate atypical microRNAs. RNA silencing is a conserved eukaryotic gene expression regulatory mechanism mediated by small RNAs. In Caenorhabditis elegans, the accumulation of a distinct class of siRNAs synthesized by an RNA-dependent RNA polymerase (RdRP) requires the PIR-1 phosphatase. However, the function of PIR-1 in RNAi has remained unclear. Since mammals lack an analogous siRNA biogenesis pathway, an RNA silencing role for the mammalian PIR-1 homolog (dual specificity phosphatase 11 [DUSP11]) was unexpected. Here, we show that the RNA triphosphatase activity of DUSP11 promotes the RNA silencing activity of viral microRNAs (miRNAs) derived from RNA polymerase III (RNAP III) transcribed precursors. Our results demonstrate that DUSP11 converts the 5′ triphosphate of miRNA precursors to a 5′ monophosphate, promoting loading of derivative 5p miRNAs into Argonaute proteins via a Dicer-coupled 5′ monophosphate-dependent strand selection mechanism. This mechanistic insight supports a likely shared function for PIR-1 in C. elegans. Furthermore, we show that DUSP11 modulates the 5′ end phosphate group and/or steady-state level of several host RNAP III transcripts, including vault RNAs and Alu transcripts. This study shows that steady-state levels of select noncoding RNAs are regulated by DUSP11 and defines a previously unknown portal for small RNA-mediated silencing in mammals, revealing that DUSP11-dependent RNA silencing activities are shared among diverse metazoans.
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Affiliation(s)
- James M Burke
- Institute for Cellular and Molecular Biology, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Department of Molecular Biosciences, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,John Ring LaMontagne Center for Infectious Disease, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Rodney P Kincaid
- Institute for Cellular and Molecular Biology, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Department of Molecular Biosciences, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,John Ring LaMontagne Center for Infectious Disease, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Ryan M Nottingham
- Institute for Cellular and Molecular Biology, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Department of Molecular Biosciences, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Department of Molecular Biosciences, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Christopher S Sullivan
- Institute for Cellular and Molecular Biology, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, USA.,Department of Molecular Biosciences, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.,John Ring LaMontagne Center for Infectious Disease, College of Natural Sciences, The University of Texas at Austin, Austin, Texas 78712, USA
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12
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Tang L, Chen HY, Hao NB, Tang B, Guo H, Yong X, Dong H, Yang SM. microRNA inhibitors: Natural and artificial sequestration of microRNA. Cancer Lett 2017; 407:139-147. [PMID: 28602827 DOI: 10.1016/j.canlet.2017.05.025] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/16/2017] [Accepted: 05/31/2017] [Indexed: 12/14/2022]
Abstract
MicroRNA (miRNAs) is post-transcriptional regulator of mRNA. However, the prevalence and activity of miRNA are regulated by other regulators. miRNA inhibitors are natural or artificial RNA transcripts that sequestrate miRNAs and decrease or even eliminate miRNA activity. Competing endogenous RNAs (ceRNAs) are natural and intracellular miRNA inhibitors that compete to bind to shared miRNA recognition elements (MREs) to decrease microRNA availability and relieve the repression of target RNAs. In recent years, studies have revealed that ceRNA crosstalk is involved in many pathophysiological processes and adds a new dimension to miRNA regulation. Artificial miRNA inhibitors are RNA transcripts that are synthesized via chemical and genetic methods. Artificial miRNA inhibitors can be used in miRNA loss-of-function research and gene therapies for certain diseases. In this review, we summarize the recent advances in the two different types of miRNA inhibitors.
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Affiliation(s)
- Li Tang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hong-Yan Chen
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Ning-Bo Hao
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Bo Tang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hong Guo
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xin Yong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Shi-Ming Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
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13
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Read DF, Waller TJ, Tse E, Southworth DR, Engelke DR, Smaldino PJ. Aggregation of Mod5 is affected by tRNA binding with implications for tRNA gene-mediated silencing. FEBS Lett 2017; 591:1601-1610. [PMID: 28303570 DOI: 10.1002/1873-3468.12627] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/09/2017] [Accepted: 03/13/2017] [Indexed: 12/24/2022]
Abstract
Mod5 is a multifunctional protein that modifies a subset of tRNAs in the cytoplasm and is also required for an RNA-mediated form of transcriptional silencing. Previous in vivo studies have shown that the nuclear silencing function of Mod5 does not require that the causative tRNA gene encode a Mod5 substrate, although Mod5 is still required. However, previous data have not directly tested whether Mod5 can directly bind substrate and nonsubstrate RNAs. We herein demonstrate that Mod5 directly binds to both substrate and nonsubstrate RNAs, including a highly structured, non-tRNA sequence (5S-rRNA), consistent with previous in vivo data. Furthermore, we show that some RNAs drastically change the aggregation behavior of Mod5 with implications for tRNA gene-mediated silencing.
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Affiliation(s)
- David F Read
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Thomas J Waller
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Eric Tse
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Daniel R Southworth
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - David R Engelke
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,University of Colorado Denver/Anschutz Medical Campus, Aurora, CO, USA
| | - Philip J Smaldino
- Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.,Biology, Ball State University, Muncie, IN, USA
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14
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Burke JM, Sullivan CS. DUSP11 - An RNA phosphatase that regulates host and viral non-coding RNAs in mammalian cells. RNA Biol 2017; 14:1457-1465. [PMID: 28296624 PMCID: PMC5785229 DOI: 10.1080/15476286.2017.1306169] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dual-specificity phosphatase 11 (DUSP11) is a conserved protein tyrosine phosphatase (PTP) in metazoans. The cellular substrates and physiologic activities of DUSP11 remain largely unknown. In nematodes, DUSP11 is required for normal development and RNA interference against endogenous RNAs (endo-RNAi) via molecular mechanisms that are not well understood. However, mammals lack analogous endo-RNAi pathways and consequently, a role for DUSP11 in mammalian RNA silencing was unanticipated. Recent work from our laboratory demonstrated that DUSP11 activity alters the silencing potential of noncanonical viral miRNAs in mammalian cells. Our studies further uncovered direct cellular substrates of DUSP11 and suggest that DUSP11 is part of regulatory pathway that controls the abundance of select triphosphorylated noncoding RNAs. Here, we highlight recent findings and present new data that advance understanding of mammalian DUSP11 during gene silencing and discuss the emerging biological activities of DUSP11 in mammalian cells.
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Affiliation(s)
- James M Burke
- a The University of Texas at Austin , Center for Systems and Synthetic Biology, Center for Infectious Disease and Department of Molecular Biosciences , Austin , TX , USA
| | - Christopher S Sullivan
- a The University of Texas at Austin , Center for Systems and Synthetic Biology, Center for Infectious Disease and Department of Molecular Biosciences , Austin , TX , USA
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15
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Waller TJ, Read DF, Engelke DR, Smaldino PJ. The human tRNA-modifying protein, TRIT1, forms amyloid fibers in vitro. Gene 2016; 612:19-24. [PMID: 27984194 DOI: 10.1016/j.gene.2016.10.041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/24/2016] [Accepted: 10/27/2016] [Indexed: 12/19/2022]
Abstract
TRIT1 is a highly conserved tRNA isopentenyl transferase that modifies a subset of tRNAs in human cells and is a candidate tumor suppressor in lung cancer in certain ethnic populations. The yeast homologue, Mod5, has similar tRNA-modifying functions in the cytoplasm and is required for the transcriptional silencing activity of RNA polymerase II promoters near tRNA genes in the nucleus, a phenomenon termed tRNA gene mediated (tgm) silencing. Furthermore, Mod5 can fold into amyloid fibers in vitro and in vivo, which confers resistance to certain fungicides in yeast. Since TRIT1 complements both tRNA modifying and tgm-silencing activities in yeast where the Mod5 gene has been deleted, it seemed possible that TRIT1 might also have amyloid-forming capabilities. Here we show that TRIT1, like Mod5, directly binds to tRNAs that are both substrate and non-substrates for modification with similar affinity, and to an unstructured, non-tRNA. Binding appears to involve distinct protein-RNA multimers which decrease in electrophoretic mobility as the protein to RNA ratio increases. Furthermore, we characterize TRIT1 as a novel human amyloid fiber forming protein. We discuss these data in light of TRIT1's functional roles and possible implications for disease.
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Affiliation(s)
- T J Waller
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - D F Read
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - D R Engelke
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States; University of Denver, Aurora, CO 80045, United States.
| | - P J Smaldino
- Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States; Biology, Ball State University, Muncie, IN 47306, United States.
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16
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Hasler D, Meister G. From tRNA to miRNA: RNA-folding contributes to correct entry into noncoding RNA pathways. FEBS Lett 2016; 590:2354-63. [DOI: 10.1002/1873-3468.12294] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 07/05/2016] [Accepted: 07/07/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Daniele Hasler
- Biochemistry Center Regensburg (BZR); Laboratory for RNA Biology; University of Regensburg; Germany
| | - Gunter Meister
- Biochemistry Center Regensburg (BZR); Laboratory for RNA Biology; University of Regensburg; Germany
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17
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Human Ribosomal RNA-Derived Resident MicroRNAs as the Transmitter of Information upon the Cytoplasmic Cancer Stress. BIOMED RESEARCH INTERNATIONAL 2016; 2016:7562085. [PMID: 27517048 PMCID: PMC4969525 DOI: 10.1155/2016/7562085] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 06/19/2016] [Indexed: 12/13/2022]
Abstract
Dysfunction of ribosome biogenesis induces divergent ribosome-related diseases including ribosomopathy and occasionally results in carcinogenesis. Although many defects in ribosome-related genes have been investigated, little is known about contribution of ribosomal RNA (rRNA) in ribosome-related disorders. Meanwhile, microRNA (miRNA), an important regulator of gene expression, is derived from both coding and noncoding region of the genome and is implicated in various diseases. Therefore, we performed in silico analyses using M-fold, TargetScan, GeneCoDia3, and so forth to investigate RNA relationships between rRNA and miRNA against cellular stresses. We have previously shown that miRNA synergism is significantly correlated with disease and the miRNA package is implicated in memory for diseases; therefore, quantum Dynamic Nexus Score (DNS) was also calculated using MESer program. As a result, seventeen RNA sequences identical with known miRNAs were detected in the human rRNA and termed as rRNA-hosted miRNA analogs (rmiRNAs). Eleven of them were predicted to form stem-loop structures as pre-miRNAs, and especially one stem-loop was completely identical with hsa-pre-miR-3678 located in the non-rDNA region. Thus, these rmiRNAs showed significantly high DNS values, participation in regulation of cancer-related pathways, and interaction with nucleolar RNAs, suggesting that rmiRNAs may be stress-responsible resident miRNAs which transmit stress-tuning information in multiple levels.
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18
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Woolnough JL, Atwood BL, Liu Z, Zhao R, Giles KE. The Regulation of rRNA Gene Transcription during Directed Differentiation of Human Embryonic Stem Cells. PLoS One 2016; 11:e0157276. [PMID: 27299313 PMCID: PMC4907514 DOI: 10.1371/journal.pone.0157276] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 05/26/2016] [Indexed: 11/18/2022] Open
Abstract
It has become increasingly clear that proper cellular control of pluripotency and differentiation is related to the regulation of rRNA synthesis. To further our understanding of the role that the regulation of rRNA synthesis has in pluripotency we monitored rRNA synthesis during the directed differentiation of human embryonic stem cells (hESCs). We discovered that the rRNA synthesis rate is reduced ~50% within 6 hours of ACTIVIN A treatment. This precedes reductions in expression of specific stem cell markers and increases in expression of specific germ layer markers. The reduction in rRNA synthesis is concomitant with dissociation of the Pol I transcription factor, UBTF, from the rRNA gene promoter and precedes any increase to heterochromatin throughout the rRNA gene. To directly investigate the role of rRNA synthesis in pluripotency, hESCs were treated with the Pol I inhibitor, CX-5461. The direct reduction of rRNA synthesis by CX-5461 induces the expression of markers for all three germ layers, reduces the expression of pluripotency markers, and is overall similar to the ACTIVIN A induced changes. This work indicates that the dissociation of UBTF from the rRNA gene, and corresponding reduction in transcription, represent early regulatory events during the directed differentiation of pluripotent stem cells.
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Affiliation(s)
- Jessica L Woolnough
- UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America
| | - Blake L Atwood
- UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America
| | - Zhong Liu
- UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America
| | - Rui Zhao
- UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America
| | - Keith E Giles
- UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, The University of Alabama at Birmingham, Birmingham, Alabama 35294, United States of America
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19
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Atwood BL, Woolnough JL, Lefevre GM, Saint Just Ribeiro M, Felsenfeld G, Giles KE. Human Argonaute 2 Is Tethered to Ribosomal RNA through MicroRNA Interactions. J Biol Chem 2016; 291:17919-28. [PMID: 27288410 DOI: 10.1074/jbc.m116.725051] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Indexed: 11/06/2022] Open
Abstract
The primary role of the RNAi machinery is to promote mRNA degradation within the cytoplasm in a microRNA-dependent manner. However, both Dicer and the Argonaute protein family have expanded roles in gene regulation within the nucleus. To further our understanding of this role, we have identified chromatin binding sites for AGO2 throughout the 45S region of the human rRNA gene. The location of these sites was mirrored by the positions of AGO2 cross-linking sites identified via PAR-CLIP-seq. AGO2 binding to the rRNA within the nucleus was confirmed by RNA immunoprecipitation and quantitative-PCR. To explore a possible mechanism by which AGO2 could be recruited to the rRNA, we identified 1174 regions within the 45S rRNA transcript that have the ability to form a perfect duplex with position 2-6 (seed sequence) of each microRNA expressed in HEK293T cells. Of these potential AGO2 binding sites, 479 occurred within experimentally verified AGO2-rRNA cross-linking sites. The ability of AGO2 to cross-link to rRNA was almost completely lost in a DICER knock-out cell line. The transfection of miR-92a-2-3p into the noDICE cell line facilitated AGO2 cross-linking at a region of the rRNA that has a perfect seed match at positions 3-8, including a single G-U base pair. Knockdown of AGO2 within HEK293T cells causes a slight, but statistically significant increase in the overall rRNA synthesis rate but did not impact the ratio of processing intermediates or the recruitment of the Pol I transcription factor UBTF.
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Affiliation(s)
- Blake L Atwood
- From the UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35209 and
| | - Jessica L Woolnough
- From the UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35209 and
| | - Gaelle M Lefevre
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland
| | - Mariana Saint Just Ribeiro
- From the UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35209 and
| | - Gary Felsenfeld
- Laboratory of Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland
| | - Keith E Giles
- From the UAB Stem Cell Institute, Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama 35209 and
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20
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RNA Polymerase III Advances: Structural and tRNA Functional Views. Trends Biochem Sci 2016; 41:546-559. [PMID: 27068803 DOI: 10.1016/j.tibs.2016.03.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/03/2016] [Accepted: 03/09/2016] [Indexed: 12/25/2022]
Abstract
RNA synthesis in eukaryotes is divided among three RNA polymerases (RNAPs). RNAP III transcribes hundreds of tRNA genes and fewer additional short RNA genes. We survey recent work on transcription by RNAP III including an atomic structure, mechanisms of action, interactions with chromatin and retroposons, and a conserved link between its activity and a tRNA modification that enhances mRNA decoding. Other new work suggests important mechanistic connections to oxidative stress, autoimmunity and cancer, embryonic stem cell pluripotency, and tissue-specific developmental effects. We consider that, for some of its complex functions, variation in RNAP III activity levels lead to nonuniform changes in tRNAs that can shift the translation profiles of key codon-biased mRNAs with resultant phenotypes or disease states.
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21
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Kalantari R, Chiang CM, Corey DR. Regulation of mammalian transcription and splicing by Nuclear RNAi. Nucleic Acids Res 2016; 44:524-37. [PMID: 26612865 PMCID: PMC4737150 DOI: 10.1093/nar/gkv1305] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/21/2022] Open
Abstract
RNA interference (RNAi) is well known as a mechanism for controlling mammalian mRNA translation in the cytoplasm, but what would be the consequences if it also functions in cell nuclei? Although RNAi has also been found in nuclei of plants, yeast, and other organisms, there has been relatively little progress towards understanding the potential involvement of mammalian RNAi factors in nuclear processes including transcription and splicing. This review summarizes evidence for mammalian RNAi factors in cell nuclei and mechanisms that might contribute to the control of gene expression. When RNAi factors bind small RNAs, they form ribonucleoprotein complexes that can be selective for target sequences within different classes of nuclear RNA substrates. The versatility of nuclear RNAi may supply a previously underappreciated layer of regulation to transcription, splicing, and other nuclear processes.
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Affiliation(s)
- Roya Kalantari
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA
| | - Cheng-Ming Chiang
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-8807, USA
| | - David R Corey
- Departments of Pharmacology & Biochemistry, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA
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