1
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Chen L, Roake CM, Maccallini P, Bavasso F, Dehghannasiri R, Santonicola P, Mendoza-Ferreira N, Scatolini L, Rizzuti L, Esposito A, Gallotta I, Francia S, Cacchione S, Galati A, Palumbo V, Kobin MA, Tartaglia G, Colantoni A, Proietti G, Wu Y, Hammerschmidt M, De Pittà C, Sales G, Salzman J, Pellizzoni L, Wirth B, Di Schiavi E, Gatti M, Artandi S, Raffa GD. TGS1 impacts snRNA 3'-end processing, ameliorates survival motor neuron-dependent neurological phenotypes in vivo and prevents neurodegeneration. Nucleic Acids Res 2022; 50:12400-12424. [PMID: 35947650 PMCID: PMC9757054 DOI: 10.1093/nar/gkac659] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 07/21/2022] [Indexed: 12/24/2022] Open
Abstract
Trimethylguanosine synthase 1 (TGS1) is a highly conserved enzyme that converts the 5'-monomethylguanosine cap of small nuclear RNAs (snRNAs) to a trimethylguanosine cap. Here, we show that loss of TGS1 in Caenorhabditis elegans, Drosophila melanogaster and Danio rerio results in neurological phenotypes similar to those caused by survival motor neuron (SMN) deficiency. Importantly, expression of human TGS1 ameliorates the SMN-dependent neurological phenotypes in both flies and worms, revealing that TGS1 can partly counteract the effects of SMN deficiency. TGS1 loss in HeLa cells leads to the accumulation of immature U2 and U4atac snRNAs with long 3' tails that are often uridylated. snRNAs with defective 3' terminations also accumulate in Drosophila Tgs1 mutants. Consistent with defective snRNA maturation, TGS1 and SMN mutant cells also exhibit partially overlapping transcriptome alterations that include aberrantly spliced and readthrough transcripts. Together, these results identify a neuroprotective function for TGS1 and reinforce the view that defective snRNA maturation affects neuronal viability and function.
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Affiliation(s)
- Lu Chen
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Cancer Signaling and Epigenetics Program and Cancer Epigenetics Institute, Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Caitlin M Roake
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Roozbeh Dehghannasiri
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biomedical Data Science, Stanford University, Stanford, CA 94305, USA
| | | | - Natalia Mendoza-Ferreira
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Institute for Genetics, University of Cologne, 50931 Cologne, Germany
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Ludovico Rizzuti
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | | | - Ivan Gallotta
- Institute of Genetics and Biophysics, IGB-ABT, CNR, Naples, Italy
| | - Sofia Francia
- IFOM-The FIRC Institute of Molecular Oncology, Milan, Italy
- Istituto di Genetica Molecolare, CNR-Consiglio Nazionale delle Ricerche, Pavia, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
| | - Marie A Kobin
- Cancer Signaling and Epigenetics Program and Cancer Epigenetics Institute, Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Gian Gaetano Tartaglia
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome 00161, Italy
- Center for Human Technology, Fondazione Istituto Italiano di Tecnologia (IIT), Genoa 16152, Italy
| | - Alessio Colantoni
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome 00161, Italy
- Center for Human Technology, Fondazione Istituto Italiano di Tecnologia (IIT), Genoa 16152, Italy
| | - Gabriele Proietti
- Center for Life Nano- & Neuro-Science, Fondazione Istituto Italiano di Tecnologia (IIT), Rome 00161, Italy
- Center for Human Technology, Fondazione Istituto Italiano di Tecnologia (IIT), Genoa 16152, Italy
| | - Yunming Wu
- Cancer Signaling and Epigenetics Program and Cancer Epigenetics Institute, Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Matthias Hammerschmidt
- Institute for Zoology, Developmental Biology, University of Cologne, 50674 Cologne, Germany
| | | | - Gabriele Sales
- Department of Biology, University of Padova, Padua, Italy
| | - Julia Salzman
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biomedical Data Science, Stanford University, Stanford, CA 94305, USA
| | - Livio Pellizzoni
- Center for Motor Neuron Biology and Disease, Columbia University, NY 10032, USA
- Department of Pathology and Cell Biology, Columbia University, NY 10032, USA
- Department of Neurology, Columbia University, NY 10032, USA
| | - Brunhilde Wirth
- Institute of Human Genetics, Center for Molecular Medicine Cologne, Institute for Genetics, University of Cologne, 50931 Cologne, Germany
- Center for Rare Diseases, University Hospital of Cologne, University of Cologne, 50931 Cologne, Germany
| | - Elia Di Schiavi
- Institute of Biosciences and BioResources, IBBR, CNR, Naples, Italy
- Institute of Genetics and Biophysics, IGB-ABT, CNR, Naples, Italy
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
| | - Steven E Artandi
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Grazia D Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza University of Rome, Rome, Italy
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2
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Takeuchi C, Yokoshi M, Kondo S, Shibuya A, Saito K, Fukaya T, Siomi H, Iwasaki Y. Mod(mdg4) variants repress telomeric retrotransposon HeT-A by blocking subtelomeric enhancers. Nucleic Acids Res 2022; 50:11580-11599. [PMID: 36373634 PMCID: PMC9723646 DOI: 10.1093/nar/gkac1034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/17/2022] [Accepted: 10/22/2022] [Indexed: 11/16/2022] Open
Abstract
Telomeres in Drosophila are composed of sequential non-LTR retrotransposons HeT-A, TART and TAHRE. Although they are repressed by the PIWI-piRNA pathway or heterochromatin in the germline, the regulation of these retrotransposons in somatic cells is poorly understood. In this study, we demonstrated that specific splice variants of Mod(mdg4) repress HeT-A by blocking subtelomeric enhancers in ovarian somatic cells. Among the variants, we found that the Mod(mdg4)-N variant represses HeT-A expression the most efficiently. Subtelomeric sequences bound by Mod(mdg4)-N block enhancer activity within subtelomeric TAS-R repeats. This enhancer-blocking activity is increased by the tandem association of Mod(mdg4)-N to repetitive subtelomeric sequences. In addition, the association of Mod(mdg4)-N couples with the recruitment of RNA polymerase II to the subtelomeres, which reinforces its enhancer-blocking function. Our findings provide novel insights into how telomeric retrotransposons are regulated by the specific variants of insulator proteins associated with subtelomeric sequences.
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Affiliation(s)
- Chikara Takeuchi
- Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Moe Yokoshi
- Laboratory of Transcription Dynamics, Research Center for Biological Visualization, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo 113-0032, Japan
| | - Shu Kondo
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Shizuoka 411-8540, Japan
| | - Aoi Shibuya
- Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Kuniaki Saito
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Shizuoka 411-8540, Japan
| | - Takashi Fukaya
- Laboratory of Transcription Dynamics, Research Center for Biological Visualization, Institute for Quantitative Biosciences, The University of Tokyo, Tokyo 113-0032, Japan,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo 113-0032, Japan
| | | | - Yuka W Iwasaki
- To whom correspondence should be addressed. Tel: +81 3 5363 3529; Fax: +81 3 5363 3266;
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3
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Vedelek B, Kovács Á, Boros IM. Evolutionary mode for the functional preservation of fast-evolving Drosophila telomere capping proteins. Open Biol 2021; 11:210261. [PMID: 34784790 PMCID: PMC8596017 DOI: 10.1098/rsob.210261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
DNA end protection is fundamental for the long-term preservation of the genome. In vertebrates the Shelterin protein complex protects telomeric DNA ends, thereby contributing to the maintenance of genome integrity. In the Drosophila genus, this function is thought to be performed by the Terminin complex, an assembly of fast-evolving subunits. Considering that DNA end protection is fundamental for successful genome replication, the accelerated evolution of Terminin subunits is counterintuitive, as conservation is supposed to maintain the assembly and concerted function of the interacting partners. This problem extends over Drosophila telomere biology and provides insight into the evolution of protein assemblies. In order to learn more about the mechanistic details of this phenomenon we have investigated the intra- and interspecies assemblies of Verrocchio and Modigliani, two Terminin subunits using in vitro assays. Based on our results and on homology-based three-dimensional models for Ver and Moi, we conclude that both proteins contain Ob-fold and contribute to the ssDNA binding of the Terminin complex. We propose that the preservation of Ver function is achieved by conservation of specific amino acids responsible for folding or localized in interacting surfaces. We also provide here the first evidence on Moi DNA binding.
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Affiliation(s)
- Balázs Vedelek
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Ákos Kovács
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | - Imre M. Boros
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary,Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
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4
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Cheng L, Zhang Y, Zhang Y, Chen T, Xu YZ, Rong YS. Loss of the RNA trimethylguanosine cap is compatible with nuclear accumulation of spliceosomal snRNAs but not pre-mRNA splicing or snRNA processing during animal development. PLoS Genet 2020; 16:e1009098. [PMID: 33085660 PMCID: PMC7605716 DOI: 10.1371/journal.pgen.1009098] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 11/02/2020] [Accepted: 09/07/2020] [Indexed: 12/31/2022] Open
Abstract
The 2,2,7-trimethylguanosine (TMG) cap is one of the first identified modifications on eukaryotic RNAs. TMG, synthesized by the conserved Tgs1 enzyme, is abundantly present on snRNAs essential for pre-mRNA splicing. Results from ex vivo experiments in vertebrate cells suggested that TMG ensures nuclear localization of snRNAs. Functional studies of TMG using tgs1 mutations in unicellular organisms yield results inconsistent with TMG being indispensable for either nuclear import or splicing. Utilizing a hypomorphic tgs1 mutation in Drosophila, we show that TMG reduction impairs germline development by disrupting the processing, particularly of introns with smaller sizes and weaker splice sites. Unexpectedly, loss of TMG does not disrupt snRNAs localization to the nucleus, disputing an essential role of TMG in snRNA transport. Tgs1 loss also leads to defective 3' processing of snRNAs. Remarkably, stronger tgs1 mutations cause lethality without severely disrupting splicing, likely due to the preponderance of TMG-capped snRNPs. Tgs1, a predominantly nucleolar protein in Drosophila, likely carries out splicing-independent functions indispensable for animal development. Taken together, our results suggest that nuclear import is not a conserved function of TMG. As a distinctive structure on RNA, particularly non-coding RNA, we suggest that TMG prevents spurious interactions detrimental to the function of RNAs that it modifies.
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Affiliation(s)
- Lin Cheng
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yu Zhang
- Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Yi Zhang
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, United States of America
| | - Tao Chen
- School of Life Sciences, Sun Yat-sen University, Guangzhou, China
- Hengyang College of Medicine, University of South China, Hengyang, China
| | - Yong-Zhen Xu
- College of Life Sciences, Wuhan University, Wuhan, China
| | - Yikang S. Rong
- Hengyang College of Medicine, University of South China, Hengyang, China
- * E-mail:
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5
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Maccallini P, Bavasso F, Scatolini L, Bucciarelli E, Noviello G, Lisi V, Palumbo V, D'Angeli S, Cacchione S, Cenci G, Ciapponi L, Wakefield JG, Gatti M, Raffa GD. Intimate functional interactions between TGS1 and the Smn complex revealed by an analysis of the Drosophila eye development. PLoS Genet 2020; 16:e1008815. [PMID: 32453722 PMCID: PMC7289441 DOI: 10.1371/journal.pgen.1008815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/11/2020] [Accepted: 04/30/2020] [Indexed: 11/27/2022] Open
Abstract
Trimethylguanosine synthase 1 (TGS1) is a conserved enzyme that mediates formation of the trimethylguanosine cap on several RNAs, including snRNAs and telomerase RNA. Previous studies have shown that TGS1 binds the Survival Motor Neuron (SMN) protein, whose deficiency causes spinal muscular atrophy (SMA). Here, we analyzed the roles of the Drosophila orthologs of the human TGS1 and SMN genes. We show that the Drosophila TGS1 protein (dTgs1) physically interacts with all subunits of the Drosophila Smn complex (Smn, Gem2, Gem3, Gem4 and Gem5), and that a human TGS1 transgene rescues the mutant phenotype caused by dTgs1 loss. We demonstrate that both dTgs1 and Smn are required for viability of retinal progenitor cells and that downregulation of these genes leads to a reduced eye size. Importantly, overexpression of dTgs1 partially rescues the eye defects caused by Smn depletion, and vice versa. These results suggest that the Drosophila eye model can be exploited for screens aimed at the identification of genes and drugs that modify the phenotypes elicited by Tgs1 and Smn deficiency. These modifiers could help to understand the molecular mechanisms underlying SMA pathogenesis and devise new therapies for this genetic disease. We explored the functional relationships between TGS1 and SMN using Drosophila as model organism. TGS1 is an enzyme that modifies the structure of the 5’-end of several RNAs, including telomerase RNA and the small nuclear RNAs (snRNAs) that are required for messenger RNA maturation. The SMN protein regulates snRNAs biogenesis and mutations in human SMN cause Spinal Muscular Atrophy (SMA), a devastating disorder characterized by neurodegeneration, progressive paralysis and death. We show that mutations in the Drosophila TGS1 (dTgs1) gene cause lethality, which is rescued by a human TGS1 transgene. We also show that the dTgs1 protein physically interacts with all subunits of the Smn complex, and that downregulation of either dTgs1 or Smn leads to a reduced Drosophila eye size. Notably, overexpression of dTgs1 partially rescues the eye defects caused by Smn knockdown, and vice versa, indicating that these genes cooperate in eye development. These results suggest that the eye model can be exploited for screens aimed at detection of chemical and genetic modifiers of the eye mutant phenotype elicited by dTgs1 and Smn deficiency, providing new clues about SMA pathogenesis and potential therapies.
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Affiliation(s)
- Paolo Maccallini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Francesca Bavasso
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Livia Scatolini
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | | | - Gemma Noviello
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Veronica Lisi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Valeria Palumbo
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Simone D'Angeli
- Dipartimento di Biologia Ambientale, Sapienza University of Rome, Rome, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - Giovanni Cenci
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Fondazione Cenci Bolognetti, Istituto Pasteur, Rome, Italy
| | - Laura Ciapponi
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
| | - James G. Wakefield
- Biosciences/Living Systems Institute, College of Life and Environmental Sciences, University of Exeter, United Kingdom
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Rome, Italy
- * E-mail: (MG); (GDR)
| | - Grazia Daniela Raffa
- Dipartimento di Biologia e Biotecnologie “C Darwin”, Sapienza University of Rome, Rome, Italy
- * E-mail: (MG); (GDR)
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6
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Torres-Zelada EF, Stephenson RE, Alpsoy A, Anderson BD, Swanson SK, Florens L, Dykhuizen EC, Washburn MP, Weake VM. The Drosophila Dbf4 ortholog Chiffon forms a complex with Gcn5 that is necessary for histone acetylation and viability. J Cell Sci 2019; 132:jcs.214072. [PMID: 30559249 DOI: 10.1242/jcs.214072] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 12/11/2018] [Indexed: 02/05/2023] Open
Abstract
Metazoans contain two homologs of the Gcn5-binding protein Ada2, Ada2a and Ada2b, which nucleate formation of the ATAC and SAGA complexes, respectively. In Drosophila melanogaster, there are two splice isoforms of Ada2b: Ada2b-PA and Ada2b-PB. Here, we show that only the Ada2b-PB isoform is in SAGA; in contrast, Ada2b-PA associates with Gcn5, Ada3, Sgf29 and Chiffon, forming the Chiffon histone acetyltransferase (CHAT) complex. Chiffon is the Drosophila ortholog of Dbf4, which binds and activates the cell cycle kinase Cdc7 to initiate DNA replication. In flies, Chiffon and Cdc7 are required in ovary follicle cells for gene amplification, a specialized form of DNA re-replication. Although chiffon was previously reported to be dispensable for viability, here, we find that Chiffon is required for both histone acetylation and viability in flies. Surprisingly, we show that chiffon is a dicistronic gene that encodes distinct Cdc7- and CHAT-binding polypeptides. Although the Cdc7-binding domain of Chiffon is not required for viability in flies, the CHAT-binding domain is essential for viability, but is not required for gene amplification, arguing against a role in DNA replication.
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Affiliation(s)
| | - Robert E Stephenson
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Aktan Alpsoy
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Benjamin D Anderson
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Selene K Swanson
- Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA
| | - Emily C Dykhuizen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Michael P Washburn
- Stowers Institute for Medical Research, 1000 E. 50th St., Kansas City, MO 64110, USA.,Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Vikki M Weake
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA .,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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7
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Lee YCG, Leek C, Levine MT. Recurrent Innovation at Genes Required for Telomere Integrity in Drosophila. Mol Biol Evol 2017; 34:467-482. [PMID: 27836984 PMCID: PMC6307840 DOI: 10.1093/molbev/msw248] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Telomeres are nucleoprotein complexes at the ends of linear chromosomes. These specialized structures ensure genome integrity and faithful chromosome inheritance. Recurrent addition of repetitive, telomere-specific DNA elements to chromosome ends combats end-attrition, while specialized telomere-associated proteins protect naked, double-stranded chromosome ends from promiscuous repair into end-to-end fusions. Although telomere length homeostasis and end-protection are ubiquitous across eukaryotes, there is sporadic but building evidence that the molecular machinery supporting these essential processes evolves rapidly. Nevertheless, no global analysis of the evolutionary forces that shape these fast-evolving proteins has been performed on any eukaryote. The abundant population and comparative genomic resources of Drosophila melanogaster and its close relatives offer us a unique opportunity to fill this gap. Here we leverage population genetics, molecular evolution, and phylogenomics to define the scope and evolutionary mechanisms driving fast evolution of genes required for telomere integrity. We uncover evidence of pervasive positive selection across multiple evolutionary timescales. We also document prolific expansion, turnover, and expression evolution in gene families founded by telomeric proteins. Motivated by the mutant phenotypes and molecular roles of these fast-evolving genes, we put forward four alternative, but not mutually exclusive, models of intra-genomic conflict that may play out at very termini of eukaryotic chromosomes. Our findings set the stage for investigating both the genetic causes and functional consequences of telomere protein evolution in Drosophila and beyond.
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Affiliation(s)
- Yuh Chwen G Lee
- Department of Ecology and Evolution, University of Chicago, Chicago, IL
| | - Courtney Leek
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
| | - Mia T Levine
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA
- Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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8
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Vedelek B, Blastyák A, Boros IM. Cross-Species Interaction between Rapidly Evolving Telomere-Specific Drosophila Proteins. PLoS One 2015; 10:e0142771. [PMID: 26566042 PMCID: PMC4643883 DOI: 10.1371/journal.pone.0142771] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/27/2015] [Indexed: 11/25/2022] Open
Abstract
Telomere integrity in Drosophila melanogaster is maintained by a putative multisubunit complex called terminin that is believed to act in analogy to the mammalian shelterin complex in protecting chromosome ends from being recognized as sites of DNA damage. The five proteins supposed to form the terminin complex are HP1-ORC associated protein, HP1-HOAP interacting protein, Verrocchio, Drosophila Telomere Loss/Modigliani and Heterochromatic Protein 1. Four of these proteins evolve rapidly within the Drosophila genus. The accelerated evolution of terminin components may indicate the involvement of these proteins in the process by which new species arise, as the resulting divergence of terminin proteins might prevent hybrid formation, thus driving speciation. However, terminin is not an experimentally proven entity, and no biochemical studies have been performed to investigate its assembly and action in detail. Motivated by these facts in order to initiate biochemical studies on terminin function, we attempted to reconstitute terminin by co-expressing its subunits in bacteria and investigated the possible role of the fast-evolving parts of terminin components in complex assembly. Our results suggest formation of stable subcomplexes of terminin, but not of the whole complex in vitro. We found that the accelerated evolution is restricted to definable regions of terminin components, and that the divergence of D. melanogaster Drosophila Telomere Loss and D. yakuba Verrocchio proteins does not preclude their stable interaction.
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Affiliation(s)
- Balázs Vedelek
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | - András Blastyák
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Imre M. Boros
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail:
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9
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Anomalous altered expressions of downstream gene-targets in TP53-miRNA pathways in head and neck cancer. Sci Rep 2014; 4:6280. [PMID: 25186767 PMCID: PMC5385823 DOI: 10.1038/srep06280] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 08/11/2014] [Indexed: 01/21/2023] Open
Abstract
The prevalence of head and neck squamous cell carcinoma, HNSCC, continues to grow. Change in the expression of TP53 in HNSCC affects its downstream miRNAs and their gene targets, anomalously altering the expressions of the five genes, MEIS1, AGTR1, DTL, TYMS and BAK1. These expression alterations follow the repression of TP53 that upregulates miRNA-107, miRNA- 215, miRNA-34 b/c and miRNA-125b, but downregulates miRNA-155. The above five so far unreported genes are the targets of these miRNAs. Meta-analyses of microarray and RNA-Seq data followed by qRT-PCR validation unravel these new ones in HNSCC. The regulatory roles of TP53 on miRNA-155 and miRNA-125b differentiate the expressions of AGTR1 and BAK1in HNSCC vis-à-vis other carcinogenesis. Expression changes alter cell cycle regulation, angiogenic and blood cell formation, and apoptotic modes in affliction. Pathway analyses establish the resulting systems-level functional and mechanistic insights into the etiology of HNSCC.
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Fulcher N, Derboven E, Valuchova S, Riha K. If the cap fits, wear it: an overview of telomeric structures over evolution. Cell Mol Life Sci 2014; 71:847-65. [PMID: 24042202 PMCID: PMC11113737 DOI: 10.1007/s00018-013-1469-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/16/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
Genome organization into linear chromosomes likely represents an important evolutionary innovation that has permitted the development of the sexual life cycle; this process has consequently advanced nuclear expansion and increased complexity of eukaryotic genomes. Chromosome linearity, however, poses a major challenge to the internal cellular machinery. The need to efficiently recognize and repair DNA double-strand breaks that occur as a consequence of DNA damage presents a constant threat to native chromosome ends known as telomeres. In this review, we present a comparative survey of various solutions to the end protection problem, maintaining an emphasis on DNA structure. This begins with telomeric structures derived from a subset of prokaryotes, mitochondria, and viruses, and will progress into the typical telomere structure exhibited by higher organisms containing TTAGG-like tandem sequences. We next examine non-canonical telomeres from Drosophila melanogaster, which comprise arrays of retrotransposons. Finally, we discuss telomeric structures in evolution and possible switches between canonical and non-canonical solutions to chromosome end protection.
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Affiliation(s)
- Nick Fulcher
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Elisa Derboven
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Sona Valuchova
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
| | - Karel Riha
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohrgasse 3, 1030 Vienna, Austria
- Central European Institute of Technology, Kamenice 753/5, Brno, Czech Republic
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HipHop interacts with HOAP and HP1 to protect Drosophila telomeres in a sequence-independent manner. EMBO J 2010; 29:819-29. [PMID: 20057353 DOI: 10.1038/emboj.2009.394] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 12/08/2009] [Indexed: 12/30/2022] Open
Abstract
Telomeres prevent chromosome ends from being repaired as double-strand breaks (DSBs). Telomere identity in Drosophila is determined epigenetically with no sequence either necessary or sufficient. To better understand this sequence-independent capping mechanism, we isolated proteins that interact with the HP1/ORC-associated protein (HOAP) capping protein, and identified HipHop as a subunit of the complex. Loss of one protein destabilizes the other and renders telomeres susceptible to fusion. Both HipHop and HOAP are enriched at telomeres, where they also interact with the conserved HP1 protein. We developed a model telomere lacking repetitive sequences to study the distribution of HipHop, HOAP and HP1 using chromatin immunoprecipitation (ChIP). We discovered that they occupy a broad region >10 kb from the chromosome end and their binding is independent of the underlying DNA sequence. HipHop and HOAP are both rapidly evolving proteins yet their telomeric deposition is under the control of the conserved ATM and Mre11-Rad50-Nbs (MRN) proteins that modulate DNA structures at telomeres and at DSBs. Our characterization of HipHop and HOAP reveals functional analogies between the Drosophila proteins and subunits of the yeast and mammalian capping complexes, implicating conservation in epigenetic capping mechanisms.
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