201
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Ye C, Lin J, Li QQ. Discovery of alternative polyadenylation dynamics from single cell types. Comput Struct Biotechnol J 2020; 18:1012-1019. [PMID: 32382395 PMCID: PMC7200215 DOI: 10.1016/j.csbj.2020.04.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/12/2020] [Accepted: 04/14/2020] [Indexed: 12/13/2022] Open
Abstract
Alternative polyadenylation (APA) occurs in the process of mRNA maturation by adding a poly(A) tail at different locations, resulting increased diversity of mRNA isoforms and contributing to the complexity of gene regulatory network. Benefit from the development of high-throughput sequencing technologies, we could now delineate APA profiles of transcriptomes at an unprecedented pace. Especially the single cell RNA sequencing (scRNA-seq) technologies provide us opportunities to interrogate biological details of diverse and rare cell types. Despite increasing evidence showing that APA is involved in the cell type-specific regulation and function, efficient and specific laboratory methods for capturing poly(A) sites at single cell resolution are underdeveloped to date. In this review, we summarize existing experimental and computational methods for the identification of APA dynamics from diverse single cell types. A future perspective is also provided.
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Affiliation(s)
- Congting Ye
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
| | - Juncheng Lin
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
| | - Qingshun Q. Li
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA
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202
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LaMonte GM, Rocamora F, Marapana DS, Gnädig NF, Ottilie S, Luth MR, Worgall TS, Goldgof GM, Mohunlal R, Santha Kumar TR, Thompson JK, Vigil E, Yang J, Hutson D, Johnson T, Huang J, Williams RM, Zou BY, Cheung AL, Kumar P, Egan TJ, Lee MCS, Siegel D, Cowman AF, Fidock DA, Winzeler EA. Pan-active imidazolopiperazine antimalarials target the Plasmodium falciparum intracellular secretory pathway. Nat Commun 2020; 11:1780. [PMID: 32286267 PMCID: PMC7156427 DOI: 10.1038/s41467-020-15440-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 03/01/2020] [Indexed: 12/12/2022] Open
Abstract
A promising new compound class for treating human malaria is the imidazolopiperazines (IZP) class. IZP compounds KAF156 (Ganaplacide) and GNF179 are effective against Plasmodium symptomatic asexual blood-stage infections, and are able to prevent transmission and block infection in animal models. But despite the identification of resistance mechanisms in P. falciparum, the mode of action of IZPs remains unknown. To investigate, we here combine in vitro evolution and genome analysis in Saccharomyces cerevisiae with molecular, metabolomic, and chemogenomic methods in P. falciparum. Our findings reveal that IZP-resistant S. cerevisiae clones carry mutations in genes involved in Endoplasmic Reticulum (ER)-based lipid homeostasis and autophagy. In Plasmodium, IZPs inhibit protein trafficking, block the establishment of new permeation pathways, and cause ER expansion. Our data highlight a mechanism for blocking parasite development that is distinct from those of standard compounds used to treat malaria, and demonstrate the potential of IZPs for studying ER-dependent protein processing.
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Affiliation(s)
- Gregory M LaMonte
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Frances Rocamora
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Danushka S Marapana
- Division of Infection and Immunity, Walter and Eliza Hall Institute for Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Nina F Gnädig
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Sabine Ottilie
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Madeline R Luth
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Tilla S Worgall
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Gregory M Goldgof
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Laboratory Medicine, University of California, San Francisco, CA, 94143, USA
| | - Roxanne Mohunlal
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Department of Chemistry, University of Cape Town, Rondebosch, 7700, South Africa
| | - T R Santha Kumar
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Jennifer K Thompson
- Division of Infection and Immunity, Walter and Eliza Hall Institute for Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Edgar Vigil
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Jennifer Yang
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Dylan Hutson
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Trevor Johnson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Jianbo Huang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Roy M Williams
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Bing Yu Zou
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Andrea L Cheung
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Prianka Kumar
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Timothy J Egan
- Department of Chemistry, University of Cape Town, Rondebosch, 7700, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch, 7700, South Africa
| | - Marcus C S Lee
- Parasites and Microbes Programme, Wellcome Sanger Institute, Hinxton, CB10 1SA, UK
| | - Dionicio Siegel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Alan F Cowman
- Division of Infection and Immunity, Walter and Eliza Hall Institute for Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - David A Fidock
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
- Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Elizabeth A Winzeler
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA, 92093, USA.
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203
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Sehgal PB, Westley J, Lerea KM, DiSenso-Browne S, Etlinger JD. Biomolecular condensates in cell biology and virology: Phase-separated membraneless organelles (MLOs). Anal Biochem 2020; 597:113691. [PMID: 32194074 DOI: 10.1016/j.ab.2020.113691] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/06/2020] [Accepted: 03/13/2020] [Indexed: 12/12/2022]
Abstract
Membraneless organelles (MLOs) in the cytoplasm and nucleus in the form of 2D and 3D phase-separated biomolecular condensates are increasingly viewed as critical in regulating diverse cellular functions. These functions include cell signaling, immune synapse function, nuclear transcription, RNA splicing and processing, mRNA storage and translation, virus replication and maturation, antiviral mechanisms, DNA sensing, synaptic transmission, protein turnover and mitosis. Components comprising MLOs often associate with low affinity; thus cell integrity can be critical to the maintenance of the full complement of respective MLO components. Phase-separated condensates are typically metastable (shape-changing) and can undergo dramatic, rapid and reversible assembly and disassembly in response to cell signaling events, cell stress, during mitosis, and after changes in cytoplasmic "crowding" (as observed with condensates of the human myxovirus resistance protein MxA). Increasing evidence suggests that neuron-specific aberrations in phase-separation properties of RNA-binding proteins (e.g. FUS and TDP-43) and others (such as the microtubule-binding protein tau) contribute to the development of degenerative neurological diseases (e.g. amyotrophic lateral sclerosis, frontotemporal lobar degeneration, and Alzheimer's disease). Thus, studies of liquid-like phase separation (LLPS) and the formation, structure and function of MLOs are of considerable importance in understanding basic cell biology and the pathogenesis of human diseases.
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Affiliation(s)
- Pravin B Sehgal
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA; Department of Medicine, New York Medical College, Valhalla, NY, 10595, USA.
| | - Jenna Westley
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Kenneth M Lerea
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
| | - Susan DiSenso-Browne
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA; Department of Dental Medicine, Touro College of Dental Medicine, Hawthorne, NY, 10532, USA
| | - Joseph D Etlinger
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, 10595, USA
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204
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Salerno F, Turner M, Wolkers MC. Dynamic Post-Transcriptional Events Governing CD8+ T Cell Homeostasis and Effector Function. Trends Immunol 2020; 41:240-254. [DOI: 10.1016/j.it.2020.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 01/08/2020] [Accepted: 01/08/2020] [Indexed: 12/31/2022]
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205
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3' UTRs Regulate Protein Functions by Providing a Nurturing Niche during Protein Synthesis. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:95-104. [PMID: 31900325 DOI: 10.1101/sqb.2019.84.039206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Messenger RNAs (mRNAs) are the templates for protein synthesis as the coding region is translated into the amino acid sequence. mRNAs also contain 3' untranslated regions (3' UTRs) that harbor additional elements for the regulation of protein function. If the amino acid sequence of a protein is necessary and sufficient for its function, we call it 3' UTR-independent. In contrast, functions that are accomplished by protein complexes whose formation requires the presence of a specific 3' UTR are 3' UTR-dependent protein functions. We showed that 3' UTRs can regulate protein activity without affecting protein abundance, and alternative 3' UTRs can diversify protein functions. We currently think that the regulation of protein function by 3' UTRs is facilitated by the local environment at the site of protein synthesis, which we call the nurturing niche for nascent proteins. This niche is composed of the mRNA and the bound proteins that consist of RNA-binding proteins and recruited proteins. It enables the formation of specific protein complexes, as was shown for TIS granules, a recently discovered cytoplasmic membraneless organelle. This finding suggests that changing the niche for nascent proteins will alter protein activity and function, implying that cytoplasmic membraneless organelles can regulate protein function in a manner that is independent of protein abundance.
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206
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Abstract
In consistent with other membrane-bound and secretory proteins, immune checkpoint proteins go through a set of modifications in the endoplasmic reticulum (ER) to acquire their native functional structures before they function at their destinations. There are various ER-resident chaperones and enzymes synergistically regulate and catalyze the glycosylation, folding and transporting of proteins. The whole processing is under the surveillance of ER quality control system which allows the correctly folded proteins to exit from the ER with the help of coat proteinII(COPII) coated vesicles, while retains the rest of terminally misfolded ones in the ER and then eliminates them via ER-associated degradation (ERAD) or ER-to-lysosomes-associated degradation (ERLAD). The dysfunction of the ER causes ER stress which triggers unfolded protein response (UPR) to restore ER proteostasis. Unsolvable prolonged ER stress ultimately results in cell death. This chapter reviews the process that proteins undergo in the ER, and the glycosylation, folding and degradation of immune checkpoint proteins as well as the associated potential immunotherapies to date.
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207
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Prinz WA, Toulmay A, Balla T. The functional universe of membrane contact sites. Nat Rev Mol Cell Biol 2020; 21:7-24. [PMID: 31732717 PMCID: PMC10619483 DOI: 10.1038/s41580-019-0180-9] [Citation(s) in RCA: 345] [Impact Index Per Article: 86.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2019] [Indexed: 12/13/2022]
Abstract
Organelles compartmentalize eukaryotic cells, enhancing their ability to respond to environmental and developmental changes. One way in which organelles communicate and integrate their activities is by forming close contacts, often called 'membrane contact sites' (MCSs). Interest in MCSs has grown dramatically in the past decade as it is has become clear that they are ubiquitous and have a much broader range of critical roles in cells than was initially thought. Indeed, functions for MCSs in intracellular signalling (particularly calcium signalling, reactive oxygen species signalling and lipid signalling), autophagy, lipid metabolism, membrane dynamics, cellular stress responses and organelle trafficking and biogenesis have now been reported.
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Affiliation(s)
- William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Tamas Balla
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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208
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Spannl S, Tereshchenko M, Mastromarco GJ, Ihn SJ, Lee HO. Biomolecular condensates in neurodegeneration and cancer. Traffic 2019; 20:890-911. [PMID: 31606941 DOI: 10.1111/tra.12704] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 10/03/2019] [Accepted: 10/06/2019] [Indexed: 12/14/2022]
Abstract
The intracellular environment is partitioned into functionally distinct compartments containing specific sets of molecules and reactions. Biomolecular condensates, also referred to as membrane-less organelles, are diverse and abundant cellular compartments that lack membranous enclosures. Molecules assemble into condensates by phase separation; multivalent weak interactions drive molecules to separate from their surroundings and concentrate in discrete locations. Biomolecular condensates exist in all eukaryotes and in some prokaryotes, and participate in various essential house-keeping, stress-response and cell type-specific processes. An increasing number of recent studies link abnormal condensate formation, composition and material properties to a number of disease states. In this review, we discuss current knowledge and models describing the regulation of condensates and how they become dysregulated in neurodegeneration and cancer. Further research on the regulation of biomolecular phase separation will help us to better understand their role in cell physiology and disease.
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Affiliation(s)
- Stephanie Spannl
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Maria Tereshchenko
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | | | - Sean J Ihn
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Hyun O Lee
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Canada Research Chairs Program, University of Toronto, Toronto, Ontario, Canada
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209
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Yewdell JW, Dersh D, Fåhraeus R. Peptide Channeling: The Key to MHC Class I Immunosurveillance? Trends Cell Biol 2019; 29:929-939. [PMID: 31662235 DOI: 10.1016/j.tcb.2019.09.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 09/24/2019] [Accepted: 09/25/2019] [Indexed: 12/11/2022]
Abstract
MHC class I presentation of short peptides enables CD8+ T cell (TCD8+) immunosurveillance of tumors and intracellular pathogens. A key feature of the class I pathway is that the immunopeptidome is highly skewed from the cellular degradome, indicating high selectivity of the access of protease-generated peptides to class I molecules. Similarly, in professional antigen-presenting cells, peptides from minute amounts of proteins introduced into the cytosol outcompete an overwhelming supply of constitutively generated peptides. Here, we propose that antigen processing is based on substrate channeling and review recent studies from the antigen processing and cell biology fields that provide a starting point for testing this hypothesis.
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Affiliation(s)
- Jonathan W Yewdell
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases (NIAID), Bethesda, MD 20892, USA.
| | - Devin Dersh
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases (NIAID), Bethesda, MD 20892, USA
| | - Robin Fåhraeus
- Inserm, 27 rue Juliette Dodu, 750 10 Paris, France; International Centre for Cancer Vaccine Science (ICCVS), University of Gdańsk, Science, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland; Department of Medical Biosciences, Umeå University, 90187 Umeå, Sweden; RECAMO, Masaryk Memorial Cancer Institute, Zluty kopec 7, 65653 Brno, Czech Republic
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210
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Yuan F, Hankey W, Wagner EJ, Li W, Wang Q. Alternative polyadenylation of mRNA and its role in cancer. Genes Dis 2019; 8:61-72. [PMID: 33569514 PMCID: PMC7859462 DOI: 10.1016/j.gendis.2019.10.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/18/2019] [Indexed: 12/31/2022] Open
Abstract
Alternative polyadenylation (APA) is a molecular process that generates diversity at the 3′ end of RNA polymerase II transcripts from over 60% of human genes. APA is derived from the existence of multiple polyadenylation signals (PAS) within the same transcript, and results in the differential inclusion of sequence information at the 3′ end. While APA can occur between two PASs allowing for generation of transcripts with distinct coding potential from a single gene, most APA occurs within the untranslated region (3′UTR) and changes the length and content of these non-coding sequences. APA within the 3′UTR can have tremendous impact on its regulatory potential of the mRNA through a variety of mechanisms, and indeed this layer of gene expression regulation has profound impact on processes vital to cell growth and development. Recent studies have particularly highlighted the importance of APA dysregulation in cancer onset and progression. Here, we review the current knowledge of APA and its impacts on mRNA stability, translation, localization and protein localization. We also discuss the implications of APA dysregulation in cancer research and therapy.
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Affiliation(s)
- Fuwen Yuan
- Department of Pathology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - William Hankey
- Department of Pathology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX, 77555, USA
| | - Wei Li
- Department of Biological Chemistry, University of California, Irvine, CA, 92697, USA
| | - Qianben Wang
- Department of Pathology, Duke University School of Medicine, Durham, NC, 27710, USA.,Duke Cancer Institute Center for Prostate and Urologic Cancers, Duke University School of Medicine, Durham, NC, 27710, USA
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211
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Multi-strategic RNA-seq analysis reveals a high-resolution transcriptional landscape in cotton. Nat Commun 2019; 10:4714. [PMID: 31624240 PMCID: PMC6797763 DOI: 10.1038/s41467-019-12575-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 09/18/2019] [Indexed: 11/09/2022] Open
Abstract
Cotton is an important natural fiber crop, however, its comprehensive and high-resolution gene map is lacking. Here we integrate four complementary high-throughput techniques, including Pacbio long read Iso-seq, strand-specific RNA-seq, CAGE-seq, and PolyA-seq, to systematically explore the transcription landscape across 16 tissues or different organ types in Gossypium arboreum. We devise a computational pipeline, named IGIA, to reconstruct accurate gene structures from the integrated data. Our results reveal a dynamic and diverse transcriptional map in cotton: tissue-specific gene expression, alternative usage of TSSs and polyadenylation sites, hotspot of alternative splicing, and transcriptional read-through. These regulated events affect many genes in various aspects such as gain or loss of functional RNA motifs and protein domains, fine-tuning of DNA binding activity, and co-regulation for genes in the same complex or pathway. The methods and findings provide valuable resources for further functional genomic studies such as understanding natural SNP variations for plant community.
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212
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The Control Centers of Biomolecular Phase Separation: How Membrane Surfaces, PTMs, and Active Processes Regulate Condensation. Mol Cell 2019; 76:295-305. [PMID: 31604601 DOI: 10.1016/j.molcel.2019.09.016] [Citation(s) in RCA: 195] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 12/30/2022]
Abstract
Biomolecular condensation is emerging as an essential process for cellular compartmentalization. The formation of biomolecular condensates can be driven by liquid-liquid phase separation, which arises from weak, multivalent interactions among proteins and nucleic acids. A substantial body of recent work has revealed that diverse cellular processes rely on biomolecular condensation and that aberrant phase separation may cause disease. Many proteins display an intrinsic propensity to undergo phase separation. However, the mechanisms by which cells regulate phase separation to build functional condensates at the appropriate time and location are only beginning to be understood. Here, we review three key cellular mechanisms that enable the control of biomolecular phase separation: membrane surfaces, post-translational modifications, and active processes. We discuss how these mechanisms may function in concert to provide robust control over biomolecular condensates and suggest new research avenues that will elucidate how cells build and maintain these key centers of cellular compartmentalization.
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213
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The Benefits of Cotranslational Assembly: A Structural Perspective. Trends Cell Biol 2019; 29:791-803. [DOI: 10.1016/j.tcb.2019.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 07/13/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022]
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214
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Arake de Tacca LM, Pulos-Holmes MC, Floor SN, Cate JHD. PTBP1 mRNA isoforms and regulation of their translation. RNA (NEW YORK, N.Y.) 2019; 25:1324-1336. [PMID: 31263002 PMCID: PMC6800477 DOI: 10.1261/rna.070193.118] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 06/26/2019] [Indexed: 06/09/2023]
Abstract
Polypyrimidine tract-binding proteins (PTBPs) are RNA binding proteins that regulate a number of posttranscriptional events. Human PTBP1 transits between the nucleus and cytoplasm and is thought to regulate RNA processes in both. However, information about PTBP1 mRNA isoforms and regulation of PTPB1 expression remains incomplete. Here we mapped the major PTBP1 mRNA isoforms in HEK293T cells and identified alternative 5' and 3' untranslated regions (5'-UTRs, 3'-UTRs), as well as alternative splicing patterns in the protein coding region. We also assessed how the observed PTBP1 mRNA isoforms contribute to PTBP1 expression in different phases of the cell cycle. Previously, PTBP1 mRNAs were shown to crosslink to eukaryotic translation initiation factor 3 (eIF3). We find that eIF3 binds differently to each PTBP1 mRNA isoform in a cell cycle dependent manner. We also observe a strong correlation between eIF3 binding to PTBP1 mRNAs and repression of PTBP1 levels during the S phase of the cell cycle. Our results provide evidence of translational regulation of PTBP1 protein levels during the cell cycle, which may affect downstream regulation of alternative splicing and translation mediated by PTBP1 protein isoforms.
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Affiliation(s)
- Luisa M Arake de Tacca
- Graduate Study in Comparative Biochemistry, University of California, Berkeley, California 94720, USA
| | - Mia C Pulos-Holmes
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Stephen N Floor
- Department of Cell and Tissue Biology, University of California, San Francisco, California 94143, USA
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94143, USA
| | - Jamie H D Cate
- Graduate Study in Comparative Biochemistry, University of California, Berkeley, California 94720, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- California Institute for Quantitative Biosciences 3 (QB3), University of California, Berkeley, Berkeley, California 94720, USA
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215
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Feng Z, Chen X, Wu X, Zhang M. Formation of biological condensates via phase separation: Characteristics, analytical methods, and physiological implications. J Biol Chem 2019; 294:14823-14835. [PMID: 31444270 DOI: 10.1074/jbc.rev119.007895] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) facilitates the formation of condensed biological assemblies with well-delineated physical boundaries, but without lipid membrane barriers. LLPS is increasingly recognized as a common mechanism for cells to organize and maintain different cellular compartments in addition to classical membrane-delimited organelles. Membraneless condensates have many distinct features that are not present in membrane-delimited organelles and that are likely indispensable for the viability and function of living cells. Malformation of membraneless condensates is increasingly linked to human diseases. In this review, we summarize commonly used methods to investigate various forms of LLPS occurring both in 3D aqueous solution and on 2D membrane bilayers, such as LLPS condensates arising from intrinsically disordered proteins or structured modular protein domains. We then discuss, in the context of comparisons with membrane-delimited organelles, the potential functional implications of membraneless condensate formation in cells. We close by highlighting some challenges in the field devoted to studying LLPS-mediated membraneless condensate formation.
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Affiliation(s)
- Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xudong Chen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China .,Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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216
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Abstract
Most human genes have multiple sites at which RNA 3' end cleavage and polyadenylation can occur, enabling the expression of distinct transcript isoforms under different conditions. Novel methods to sequence RNA 3' ends have generated comprehensive catalogues of polyadenylation (poly(A)) sites; their analysis using innovative computational methods has revealed how poly(A) site choice is regulated by core RNA 3' end processing factors, such as cleavage factor I and cleavage and polyadenylation specificity factor, as well as by other RNA-binding proteins, particularly splicing factors. Here, we review the experimental and computational methods that have enabled the global mapping of mRNA and of long non-coding RNA 3' ends, quantification of the resulting isoforms and the discovery of regulators of alternative cleavage and polyadenylation (APA). We highlight the different types of APA-derived isoforms and their functional differences, and illustrate how APA contributes to human diseases, including cancer and haematological, immunological and neurological diseases.
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217
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Cakmak FP, Grigas AT, Keating CD. Lipid Vesicle-Coated Complex Coacervates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:7830-7840. [PMID: 31091880 PMCID: PMC7276091 DOI: 10.1021/acs.langmuir.9b00213] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Compartmentalization by complex coacervation is important across a range of different fields including subcellular and prebiotic organization, biomedicine, food science, and personal care products. Often, lipid self-assemblies such as vesicles are also present intracellularly or in commercial formulations. A systematic understanding of how phospholipid vesicles interact with different complex coacervates could provide insight and improve control over these systems. In this manuscript, anionic phospholipid vesicles were added to a series of different complex coacervate samples in which coacervates were formed by mixing one of five polycations with one of three (poly)anions that varied in chemical structure and length. Vesicles were found to assemble at the coacervate/continuous phase interface and/or form aggregates. We report how factors such as the charge density of polyelectrolytes and the charge ratio of cationic-to-anionic moieties impact the vesicle distribution in coacervate samples. Our findings emphasize the importance of interactions between vesicles and polycations in the dilute supernatant phase for determining whether the vesicles aggregate prior to assembly at the liquid-liquid interface. The uptake of an RNA oligonucleotide (A15) was also investigated to understand the effect of these liposome coatings on diffusion into coacervate droplets. Systems in which uniform vesicle coronas assemble around coacervate droplets without restricting the entry of biomolecules such as RNAs could be of interest as bioreactors.
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Affiliation(s)
- Fatma Pir Cakmak
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | - Christine D. Keating
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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218
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del Castillo U, Gnazzo MM, Turpin CGS, Nguyen KCQ, Semaya E, Lam Y, de Cruz MA, Bembenek JN, Hall DH, Riggs B, Gelfand VI, Skop AR. Conserved role for Ataxin-2 in mediating endoplasmic reticulum dynamics. Traffic 2019; 20:436-447. [PMID: 30989774 PMCID: PMC6553494 DOI: 10.1111/tra.12647] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/17/2022]
Abstract
Ataxin-2, a conserved RNA-binding protein, is implicated in the late-onset neurodegenerative disease Spinocerebellar ataxia type-2 (SCA2). SCA2 is characterized by shrunken dendritic arbors and torpedo-like axons within the Purkinje neurons of the cerebellum. Torpedo-like axons have been described to contain displaced endoplasmic reticulum (ER) in the periphery of the cell; however, the role of Ataxin-2 in mediating ER function in SCA2 is unclear. We utilized the Caenorhabditis elegans and Drosophila homologs of Ataxin-2 (ATX-2 and DAtx2, respectively) to determine the role of Ataxin-2 in ER function and dynamics in embryos and neurons. Loss of ATX-2 and DAtx2 resulted in collapse of the ER in dividing embryonic cells and germline, and ultrastructure analysis revealed unique spherical stacks of ER in mature oocytes and fragmented and truncated ER tubules in the embryo. ATX-2 and DAtx2 reside in puncta adjacent to the ER in both C. elegans and Drosophila embryos. Lastly, depletion of DAtx2 in cultured Drosophila neurons recapitulated the shrunken dendritic arbor phenotype of SCA2. ER morphology and dynamics were severely disrupted in these neurons. Taken together, we provide evidence that Ataxin-2 plays an evolutionary conserved role in ER dynamics and morphology in C. elegans and Drosophila embryos during development and in fly neurons, suggesting a possible SCA2 disease mechanism.
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Affiliation(s)
- Urko del Castillo
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Megan M. Gnazzo
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Christopher G. Sorensen Turpin
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - Ken C. Q. Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Emily Semaya
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Yuwan Lam
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Matthew A. de Cruz
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Joshua N. Bembenek
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Blake Riggs
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Vladimir I. Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Ahna R. Skop
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
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219
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Li J, Liu C. Coding or Noncoding, the Converging Concepts of RNAs. Front Genet 2019; 10:496. [PMID: 31178900 PMCID: PMC6538810 DOI: 10.3389/fgene.2019.00496] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022] Open
Abstract
Technological advances over the past decade have unraveled the remarkable complexity of RNA. The identification of small peptides encoded by long non-coding RNAs (lncRNAs) as well as regulatory functions mediated by non-coding regions of mRNAs have further complicated our understanding of the multifaceted functions of RNA. In this review, we summarize current evidence pointing to dual roles of RNA molecules defined by their coding and non-coding potentials. We also discuss how the emerging roles of RNA transform our understanding of gene expression and evolution.
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Affiliation(s)
- Jing Li
- CAS Key Laboratory of Tropical Plant Resource and Sustainable Use, Xishuangbanna Tropical Botanical Garden, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Kunming, China
| | - Changning Liu
- CAS Key Laboratory of Tropical Plant Resource and Sustainable Use, Xishuangbanna Tropical Botanical Garden, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Kunming, China
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220
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Alenquer M, Vale-Costa S, Etibor TA, Ferreira F, Sousa AL, Amorim MJ. Influenza A virus ribonucleoproteins form liquid organelles at endoplasmic reticulum exit sites. Nat Commun 2019; 10:1629. [PMID: 30967547 PMCID: PMC6456594 DOI: 10.1038/s41467-019-09549-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 03/19/2019] [Indexed: 12/12/2022] Open
Abstract
Influenza A virus has an eight-partite RNA genome that during viral assembly forms a complex containing one copy of each RNA. Genome assembly is a selective process driven by RNA-RNA interactions and is hypothesized to lead to discrete punctate structures scattered through the cytosol. Here, we show that contrary to the accepted view, formation of these structures precedes RNA-RNA interactions among distinct viral ribonucleoproteins (vRNPs), as they assemble in cells expressing only one vRNP type. We demonstrate that these viral inclusions display characteristics of liquid organelles, segregating from the cytosol without a delimitating membrane, dynamically exchanging material and adapting fast to environmental changes. We provide evidence that viral inclusions develop close to endoplasmic reticulum (ER) exit sites, depend on continuous ER-Golgi vesicular cycling and do not promote escape to interferon response. We propose that viral inclusions segregate vRNPs from the cytosol and facilitate selected RNA-RNA interactions in a liquid environment. Influenza A virus forms cytosolic inclusions containing viral ribonucleoproteins. Here, the authors show that viral inclusions form juxtaposed the endoplasmic reticulum and have liquid properties, likely constituting sites of assembly of epidemic and pandemic influenza genomes.
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Affiliation(s)
- Marta Alenquer
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal
| | - Sílvia Vale-Costa
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal
| | - Temitope Akhigbe Etibor
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal
| | - Filipe Ferreira
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal
| | - Ana Laura Sousa
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal.,Electron Microscopy Facility, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal
| | - Maria João Amorim
- Cell Biology of Viral Infection Lab, Instituto Gulbenkian de Ciência, 2780-156, Oeiras, Portugal.
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221
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Lee SH, Mayr C. Gain of Additional BIRC3 Protein Functions through 3'-UTR-Mediated Protein Complex Formation. Mol Cell 2019; 74:701-712.e9. [PMID: 30948266 DOI: 10.1016/j.molcel.2019.03.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 01/08/2019] [Accepted: 03/04/2019] [Indexed: 12/13/2022]
Abstract
Alternative 3' untranslated regions (3' UTRs) are widespread, but their functional roles are largely unknown. We investigated the function of the long BIRC3 3' UTR, which is upregulated in leukemia. The 3' UTR does not regulate BIRC3 protein localization or abundance but is required for CXCR4-mediated B cell migration. We established an experimental pipeline to study the mechanism of regulation and used mass spectrometry to identify BIRC3 protein interactors. In addition to 3'-UTR-independent interactors involved in known BIRC3 functions, we detected interactors that bind only to BIRC3 protein encoded from the mRNA with the long 3' UTR. They regulate several functions, including CXCR4 trafficking. We further identified RNA-binding proteins differentially bound to the alternative 3' UTRs and found that cooperative binding of Staufen and HuR mediates 3'-UTR-dependent complex formation. We show that the long 3' UTR is required for the formation of specific protein complexes that enable additional functions of BIRC3 protein beyond its 3'-UTR-independent functions.
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Affiliation(s)
- Shih-Han Lee
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Christine Mayr
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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222
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Abstract
Many human genes generate mRNAs with alternative 3' untranslated regions (3' UTRs), which can modulate protein function. In a recent Cell paper, Ma and Mayr (2018) unveil a major membraneless organelle, termed the TIS granule-endoplasmic reticulum (TIGER), which enables specific 3' UTRs to encipher protein localization.
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Affiliation(s)
- Bede Portz
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
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223
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Networks of mRNA Processing and Alternative Splicing Regulation in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1157:1-27. [PMID: 31342435 DOI: 10.1007/978-3-030-19966-1_1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
mRNA processing events introduce an intricate layer of complexity into gene expression processes, supporting a tremendous level of diversification of the genome's coding and regulatory potential, particularly in vertebrate species. The recent development of massive parallel sequencing methods and their adaptation to the identification and quantification of different RNA species and the dynamics of mRNA metabolism and processing has generated an unprecedented view over the regulatory networks that are established at this level, which contribute to sustain developmental, tissue specific or disease specific gene expression programs. In this chapter, we provide an overview of the recent evolution of transcriptome profiling methods and the surprising insights that have emerged in recent years regarding distinct mRNA processing events - from the 5' end to the 3' end of the molecule.
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224
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Dufau ML, Kavarthapu R. Gonadotropin Regulation Testicular RNA Helicase, Two Decades of Studies on Its Structure Function and Regulation From Its Discovery Opens a Window for Development of a Non-hormonal Oral Male Contraceptive. Front Endocrinol (Lausanne) 2019; 10:576. [PMID: 31555207 PMCID: PMC6727037 DOI: 10.3389/fendo.2019.00576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 08/07/2019] [Indexed: 12/22/2022] Open
Abstract
Gonadotropin Regulated Testicular Helicase (GRTH/DDX25) is member of the DEAD-box family of RNA helicases present in Leydig and germ cells. GRTH is the only family member regulated by hormones, luteinizing hormone, through androgen action. Male mice with knock-out of the GRTH gene are sterile, lack sperm with arrest at round spermatids. GRTH participates on the nuclear export and transport of specific mRNAs, the structural integrity of Chromatoid Bodies of round spermatids, where mRNAs are processed and stored, and in their transit to polyribosomes, where it may regulate translation of relevant genes. GRTH has a central role in the control of germ cell apoptosis and acts as negative regulator of miRNAs which regulate expression of genes involved in the progress of spermatogenesis. In Leydig cells, GRTH gene transcription is regulated by LH via autocrine actions of androgen/androgen receptor and has regulatory effects in steroidogenesis. In germ cells, androgen actions are indirect via receptors in Sertoli cells. Transgenic mice carrying GRTH 5' flanking region-GFP permitted to discern regions in the gene which directs its expression upstream, in germ cells, and downstream in Leydig cells, and the androgen-regulated transcription at interstitial (autocrine), and germ cell (paracrine) compartments. Further evidence for paracrine actions of androgen/androgen receptor is their transcriptional induction of Germ Cell Nuclear Factor as requisite up-regulator of GRTH gene transcription in round spermatids, linking androgen action to two relevant germ cell genes essential for the progress of spermatogenesis. A missense mutation of R to H at amino acid 242 of GRTH found in 5.8% of a patient population with azoospermia causes loss of the cytoplasmic phospho-GRTH species with preservation of the non-phospho form in transfected cells. Mice with knock-in of the human mutation, lack sperm due to arrest at round spermatids. This model permits to discern the function of phospho-GRTH. The GRTH phospho-site resides at a Threonine structurally adjacent to the mutant site found in patients. Molecular modeling of this site elucidated the amino acids that form the GRTH/PKA interphase and provide the basis for drug design for use as male contraceptive.
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225
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Protein trafficking through TIGER domains. Nat Rev Mol Cell Biol 2018; 20:3. [PMID: 30479375 DOI: 10.1038/s41580-018-0088-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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226
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Béthune J, Jansen RP, Feldbrügge M, Zarnack K. Membrane-Associated RNA-Binding Proteins Orchestrate Organelle-Coupled Translation. Trends Cell Biol 2018; 29:178-188. [PMID: 30455121 DOI: 10.1016/j.tcb.2018.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/28/2018] [Accepted: 10/29/2018] [Indexed: 02/02/2023]
Abstract
Proteins are positioned and act at defined subcellular locations. This is particularly important in eukaryotic cells that deliver proteins to membrane-bound organelles such as the endoplasmic reticulum (ER), mitochondria, or endosomes. It is axiomatic that organelle targeting depends mainly on polypeptide signals. However, recent results demonstrate that targeting elements within the encoding transcripts are essential for efficient protein localisation. Key readers of these elements are membrane-associated RNA-binding proteins (memRBPs) that orchestrate organelle-coupled translation. The translation products then either cross the membrane for organelle entry or hitchhike on organelle surfaces for complex assembly and co-transport. Understanding the interaction of protein- and RNA-based targeting signals is essential to decipher the molecular basis for mutant phenotypes in disease.
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Affiliation(s)
- Julien Béthune
- Heidelberg University, Biochemistry Center, Cluster of Excellence CellNetworks, 69120 Heidelberg, Germany
| | - Ralf-Peter Jansen
- Eberhard-Karls-University Tübingen, Interfaculty Institute of Biochemistry, Hoppe-Seyler-Straße 4, 72076 Tübingen, Germany
| | - Michael Feldbrügge
- Heinrich-Heine University Düsseldorf, Institute for Microbiology, Cluster of Excellence on Plant Sciences, 40204 Düsseldorf, Germany.
| | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University Frankfurt, Max-von-Laue-Str. 15, 60438 Frankfurt am Main, Germany.
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