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Li Z, Zhang B, Chan JJ, Tabatabaeian H, Tong QY, Chew XH, Fan X, Driguez P, Chan C, Cheong F, Wang S, Siew BE, Tan IJW, Lee KY, Lieske B, Cheong WK, Kappei D, Tan KK, Gao X, Tay Y. An isoform-resolution transcriptomic atlas of colorectal cancer from long-read single-cell sequencing. CELL GENOMICS 2024; 4:100641. [PMID: 39216476 DOI: 10.1016/j.xgen.2024.100641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 06/06/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024]
Abstract
Colorectal cancer (CRC) ranks as the second leading cause of cancer deaths globally. In recent years, short-read single-cell RNA sequencing (scRNA-seq) has been instrumental in deciphering tumor heterogeneities. However, these studies only enable gene-level quantification but neglect alterations in transcript structures arising from alternative end processing or splicing. In this study, we integrated short- and long-read scRNA-seq of CRC samples to build an isoform-resolution CRC transcriptomic atlas. We identified 394 dysregulated transcript structures in tumor epithelial cells, including 299 resulting from various combinations of splicing events. Second, we characterized genes and isoforms associated with epithelial lineages and subpopulations exhibiting distinct prognoses. Among 31,935 isoforms with novel junctions, 330 were supported by The Cancer Genome Atlas RNA-seq and mass spectrometry data. Finally, we built an algorithm that integrated novel peptides derived from open reading frames of recurrent tumor-specific transcripts with mass spectrometry data and identified recurring neoepitopes that may aid the development of cancer vaccines.
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Affiliation(s)
- Zhongxiao Li
- Computer Science Program, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence for Smart Health (KCSH), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence on Generative AI, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Bin Zhang
- Computer Science Program, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence for Smart Health (KCSH), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence on Generative AI, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.
| | - Jia Jia Chan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Hossein Tabatabaeian
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Qing Yun Tong
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Xiao Hong Chew
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Xiaonan Fan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Patrick Driguez
- Core Labs, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Charlene Chan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Faith Cheong
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Shi Wang
- Department of Pathology, National University Health System, Singapore 119228, Singapore
| | - Bei En Siew
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Ian Jse-Wei Tan
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Division of Colorectal Surgery, University Surgical Cluster, National University Health System, Singapore 119228, Singapore
| | - Kai-Yin Lee
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Division of Colorectal Surgery, University Surgical Cluster, National University Health System, Singapore 119228, Singapore
| | - Bettina Lieske
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Division of Colorectal Surgery, University Surgical Cluster, National University Health System, Singapore 119228, Singapore
| | - Wai-Kit Cheong
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Division of Colorectal Surgery, University Surgical Cluster, National University Health System, Singapore 119228, Singapore
| | - Dennis Kappei
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Ker-Kan Tan
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Division of Colorectal Surgery, University Surgical Cluster, National University Health System, Singapore 119228, Singapore
| | - Xin Gao
- Computer Science Program, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence for Smart Health (KCSH), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia; Center of Excellence on Generative AI, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.
| | - Yvonne Tay
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore; NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
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2
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Hossain MF, Popsuj S, Vitrinel B, Kaplan NA, Stolfi A, Christiaen L, Ruggiu M. A conserved RNA switch for acetylcholine receptor clustering at neuromuscular junctions in chordates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.05.602308. [PMID: 39005407 PMCID: PMC11245090 DOI: 10.1101/2024.07.05.602308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
In mammals, neuromuscular synapses rely on clustering of acetylcholine receptors (AChRs) in the muscle plasma membrane, ensuring optimal stimulation by motor neuron-released acetylcholine neurotransmitter. This clustering depends on a complex pathway based on alternative splicing of Agrin mRNAs by the RNA-binding proteins Nova1/2. Neuron-specific expression of Nova1/2 ensures the inclusion of small "Z" exons in Agrin, resulting in a neural-specific form of this extracellular proteoglycan carrying a short peptide motif that is required for binding to Lrp4 receptors on the muscle side, which in turn stimulate AChR clustering. Here we show that this intricate pathway is remarkably conserved in Ciona robusta, a non-vertebrate chordate in the tunicate subphylum. We use in vivo tissue-specific CRISPR/Cas9-mediated mutagenesis and heterologous "mini-gene" alternative splicing assays in cultured mammalian cells to show that Ciona Nova is also necessary and sufficient for Agrin Z exon inclusion and downstream AChR clustering. We present evidence that, although the overall pathway is well conserved, there are some surprising differences in Nova structure-function between Ciona and mammals. We further show that, in Ciona motor neurons, the transcription factor Ebf is a key activator of Nova expression, thus ultimately linking this RNA switch to a conserved, motor neuron-specific transcriptional regulatory network.
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Affiliation(s)
- Md. Faruk Hossain
- Department of Biological Sciences, St. John’s University, New York, NY, USA
| | - Sydney Popsuj
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Burcu Vitrinel
- Department of Biology, New York University, New York, NY, USA
| | | | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Lionel Christiaen
- Department of Biology, New York University, New York, NY, USA
- Michael Sars Centre, University of Bergen, Bergen, Norway
| | - Matteo Ruggiu
- Department of Biological Sciences, St. John’s University, New York, NY, USA
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3
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Saito Y, Yang Y, Saito M, Park CY, Funato K, Tabar V, Darnell RB. NOVA1 acts as an oncogenic RNA-binding protein to regulate cholesterol homeostasis in human glioblastoma cells. Proc Natl Acad Sci U S A 2024; 121:e2314695121. [PMID: 38416679 PMCID: PMC10927500 DOI: 10.1073/pnas.2314695121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/13/2024] [Indexed: 03/01/2024] Open
Abstract
NOVA1 is a neuronal RNA-binding protein identified as the target antigen of a rare autoimmune disorder associated with cancer and neurological symptoms, termed paraneoplastic opsoclonus-myoclonus ataxia. Despite the strong association between NOVA1 and cancer, it has been unclear how NOVA1 function might contribute to cancer biology. In this study, we find that NOVA1 acts as an oncogenic factor in a GBM (glioblastoma multiforme) cell line established from a patient. Interestingly, NOVA1 and Argonaute (AGO) CLIP identified common 3' untranslated region (UTR) targets, which were down-regulated in NOVA1 knockdown GBM cells, indicating a transcriptome-wide intersection of NOVA1 and AGO-microRNA (miRNA) targets regulation. NOVA1 binding to 3'UTR targets stabilized transcripts including those encoding cholesterol homeostasis related proteins. Selective inhibition of NOVA1-RNA interactions with antisense oligonucleotides disrupted GBM cancer cell fitness. The precision of our GBM CLIP studies point to both mechanism and precise RNA sequence sites to selectively inhibit oncogenic NOVA1-RNA interactions. Taken together, we find that NOVA1 is commonly overexpressed in GBM, where it can antagonize AGO2-miRNA actions and consequently up-regulates cholesterol synthesis, promoting cell viability.
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Affiliation(s)
- Yuhki Saito
- HHMI, The Rockefeller University, New York, NY10065
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, New York, NY10065
| | - Yanhong Yang
- Department of Neurosurgery, Center for Stem Cell Biology, Memorial Sloan Kettering Cancer Center, New York, NY10065
- Cancer Biology and Genetics, Sloan Kettering Institute, New York, NY10065
| | - Misa Saito
- HHMI, The Rockefeller University, New York, NY10065
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, New York, NY10065
| | - Christopher Y. Park
- HHMI, The Rockefeller University, New York, NY10065
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, New York, NY10065
| | - Kosuke Funato
- Department of Neurosurgery, Center for Stem Cell Biology, Memorial Sloan Kettering Cancer Center, New York, NY10065
- Cancer Biology and Genetics, Sloan Kettering Institute, New York, NY10065
| | - Viviane Tabar
- Department of Neurosurgery, Center for Stem Cell Biology, Memorial Sloan Kettering Cancer Center, New York, NY10065
- Cancer Biology and Genetics, Sloan Kettering Institute, New York, NY10065
| | - Robert B. Darnell
- HHMI, The Rockefeller University, New York, NY10065
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, New York, NY10065
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4
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Choi S, Cho N, Kim EM, Kim KK. The role of alternative pre-mRNA splicing in cancer progression. Cancer Cell Int 2023; 23:249. [PMID: 37875914 PMCID: PMC10594706 DOI: 10.1186/s12935-023-03094-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/06/2023] [Indexed: 10/26/2023] Open
Abstract
Alternative pre-mRNA splicing is a critical mechanism that generates multiple mRNA from a single gene, thereby increasing the diversity of the proteome. Recent research has highlighted the significance of specific splicing isoforms in cellular processes, particularly in regulating cell numbers. In this review, we examine the current understanding of the role of alternative splicing in controlling cancer cell growth and discuss specific splicing factors and isoforms and their molecular mechanisms in cancer progression. These isoforms have been found to intricately control signaling pathways crucial for cell cycle progression, proliferation, and apoptosis. Furthermore, studies have elucidated the characteristics and functional importance of splicing factors that influence cell numbers. Abnormal expression of oncogenic splicing isoforms and splicing factors, as well as disruptions in splicing caused by genetic mutations, have been implicated in the development and progression of tumors. Collectively, these findings provide valuable insights into the complex interplay between alternative splicing and cell proliferation, thereby suggesting the potential of alternative splicing as a therapeutic target for cancer.
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Affiliation(s)
- Sunkyung Choi
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Namjoon Cho
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Eun-Mi Kim
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon, 34114, Republic of Korea.
| | - Kee K Kim
- Department of Biochemistry, College of Natural Sciences, Chungnam National University, Daejeon, 34134, Republic of Korea.
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5
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Titus MB, Chang AW, Popitsch N, Ebmeier CC, Bono JM, Olesnicky EC. The identification of protein and RNA interactors of the splicing factor Caper in the adult Drosophila nervous system. Front Mol Neurosci 2023; 16:1114857. [PMID: 37435576 PMCID: PMC10332324 DOI: 10.3389/fnmol.2023.1114857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 05/19/2023] [Indexed: 07/13/2023] Open
Abstract
Post-transcriptional gene regulation is a fundamental mechanism that helps regulate the development and healthy aging of the nervous system. Mutations that disrupt the function of RNA-binding proteins (RBPs), which regulate post-transcriptional gene regulation, have increasingly been implicated in neurological disorders including amyotrophic lateral sclerosis, Fragile X Syndrome, and spinal muscular atrophy. Interestingly, although the majority of RBPs are expressed widely within diverse tissue types, the nervous system is often particularly sensitive to their dysfunction. It is therefore critical to elucidate how aberrant RNA regulation that results from the dysfunction of ubiquitously expressed RBPs leads to tissue specific pathologies that underlie neurological diseases. The highly conserved RBP and alternative splicing factor Caper is widely expressed throughout development and is required for the development of Drosophila sensory and motor neurons. Furthermore, caper dysfunction results in larval and adult locomotor deficits. Nonetheless, little is known about which proteins interact with Caper, and which RNAs are regulated by Caper. Here we identify proteins that interact with Caper in both neural and muscle tissue, along with neural specific Caper target RNAs. Furthermore, we show that a subset of these Caper-interacting proteins and RNAs genetically interact with caper to regulate Drosophila gravitaxis behavior.
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Affiliation(s)
- M. Brandon Titus
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, CO, United States
| | - Adeline W. Chang
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, CO, United States
| | - Niko Popitsch
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | | | - Jeremy M. Bono
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, CO, United States
| | - Eugenia C. Olesnicky
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, CO, United States
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6
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LaForce GR, Philippidou P, Schaffer AE. mRNA isoform balance in neuronal development and disease. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1762. [PMID: 36123820 PMCID: PMC10024649 DOI: 10.1002/wrna.1762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/11/2022] [Accepted: 08/15/2022] [Indexed: 11/07/2022]
Abstract
Balanced mRNA isoform diversity and abundance are spatially and temporally regulated throughout cellular differentiation. The proportion of expressed isoforms contributes to cell type specification and determines key properties of the differentiated cells. Neurons are unique cell types with intricate developmental programs, characteristic cellular morphologies, and electrophysiological potential. Neuron-specific gene expression programs establish these distinctive cellular characteristics and drive diversity among neuronal subtypes. Genes with neuron-specific alternative processing are enriched in key neuronal functions, including synaptic proteins, adhesion molecules, and scaffold proteins. Despite the similarity of neuronal gene expression programs, each neuronal subclass can be distinguished by unique alternative mRNA processing events. Alternative processing of developmentally important transcripts alters coding and regulatory information, including interaction domains, transcript stability, subcellular localization, and targeting by RNA binding proteins. Fine-tuning of mRNA processing is essential for neuronal activity and maintenance. Thus, the focus of neuronal RNA biology research is to dissect the transcriptomic mechanisms that underlie neuronal homeostasis, and consequently, predispose neuronal subtypes to disease. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.
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Affiliation(s)
- Geneva R LaForce
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Polyxeni Philippidou
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Ashleigh E Schaffer
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio, USA
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7
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Tajima Y, Ito K, Yuan Y, Frank MO, Saito Y, Darnell RB. NOVA1 acts on Impact to regulate hypothalamic function and translation in inhibitory neurons. Cell Rep 2023; 42:112050. [PMID: 36716149 PMCID: PMC10382602 DOI: 10.1016/j.celrep.2023.112050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/12/2022] [Accepted: 01/15/2023] [Indexed: 01/30/2023] Open
Abstract
We describe a patient haploinsufficient for the neuronal RNA binding protein NOVA1 who developed a behavioral motor hyperactivity disorder, suggesting a role of NOVA1 in postnatal motor inhibition. To investigate Nova1's action in adult Gad2+ inhibitory neurons, we generated a conditional Nova1-null mouse (Nova1-cKOGad2-cre). Strikingly, the phenotypes of these mice show many similarities to the NOVA1 haploinsufficient patient and identify a function of Nova1 in the hypothalamus. Molecularly, Nova1 loss in Gad2-positive neurons alters downstream expression of Impact mRNA, along with a subset of RNAs encoding electron transport chain-related factors and ribosomal proteins. NOVA1 stabilizes Impact mRNA by binding its 3' UTR, antagonizing the actions of miR-138 and miR-124. Together, these studies demonstrate actions of NOVA1 in adult hypothalamic neurons, mechanisms by which it functions in translation and metabolism, including through direct binding to Impact mRNA, and illuminate its role in human neurologic disease.
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Affiliation(s)
- Yoko Tajima
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Keiichi Ito
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Yuan Yuan
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Mayu O Frank
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Yuhki Saito
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Robert B Darnell
- Laboratory of Molecular Neuro-oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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8
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Buen Abad Najar CF, Burra P, Yosef N, Lareau LF. Identifying cell state-associated alternative splicing events and their coregulation. Genome Res 2022; 32:1385-1397. [PMID: 35858747 PMCID: PMC9341514 DOI: 10.1101/gr.276109.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 06/01/2022] [Indexed: 11/25/2022]
Abstract
Alternative splicing shapes the transcriptome and contributes to each cell's unique identity, but single-cell RNA sequencing (scRNA-seq) has struggled to capture the impact of alternative splicing. We previously showed that low recovery of mRNAs from single cells led to erroneous conclusions about the cell-to-cell variability of alternative splicing. Here, we present a method, Psix, to confidently identify splicing that changes across a landscape of single cells, using a probabilistic model that is robust against the data limitations of scRNA-seq. Its autocorrelation-inspired approach finds patterns of alternative splicing that correspond to patterns of cell identity, such as cell type or developmental stage, without the need for explicit cell clustering, labeling, or trajectory inference. Applying Psix to data that follow the trajectory of mouse brain development, we identify exons whose alternative splicing patterns cluster into modules of coregulation. We show that the exons in these modules are enriched for binding by distinct neuronal splicing factors and that their changes in splicing correspond to changes in expression of these splicing factors. Thus, Psix reveals cell type-dependent splicing patterns and the wiring of the splicing regulatory networks that control them. Our new method will enable scRNA-seq analysis to go beyond transcription to understand the roles of post-transcriptional regulation in determining cell identity.
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Affiliation(s)
| | - Prakruthi Burra
- Center for Computational Biology, University of California, Berkeley, California 94720, USA
| | - Nir Yosef
- Center for Computational Biology, University of California, Berkeley, California 94720, USA
- Department of Electrical Engineering and Computer Science, University of California, Berkeley, California 94720, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts 02139, USA
- Chan Zuckerberg Biohub, San Francisco, California 94158, USA
| | - Liana F Lareau
- Center for Computational Biology, University of California, Berkeley, California 94720, USA
- Chan Zuckerberg Biohub, San Francisco, California 94158, USA
- Department of Bioengineering, University of California, Berkeley, California 94720, USA
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9
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Abstract
Autism is a common and complex neurologic disorder whose scientific underpinnings have begun to be established in the past decade. The essence of this breakthrough has been a focus on families, where genetic analyses are strongest, versus large-scale, case-control studies. Autism genetics has progressed in parallel with technology, from analyses of copy number variation to whole-exome sequencing (WES) and whole-genome sequencing (WGS). Gene mutations causing complete loss of function account for perhaps one-third of cases, largely detected through WES. This limitation has increased interest in understanding the regulatory variants of genes that contribute in more subtle ways to the disorder. Strategies combining biochemical analysis of gene regulation, WGS analysis of the noncoding genome, and machine learning have begun to succeed. The emerging picture is that careful control of the amounts of transcription, mRNA, and proteins made by key brain genes-stoichiometry-plays a critical role in defining the clinical features of autism.
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Affiliation(s)
- Robert B Darnell
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA;
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10
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Knupp D, Cooper DA, Saito Y, Darnell RB, Miura P. NOVA2 regulates neural circRNA biogenesis. Nucleic Acids Res 2021; 49:6849-6862. [PMID: 34157123 PMCID: PMC8266653 DOI: 10.1093/nar/gkab523] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 05/03/2021] [Accepted: 06/09/2021] [Indexed: 12/14/2022] Open
Abstract
Circular RNAs (circRNAs) are highly expressed in the brain and their expression increases during neuronal differentiation. The factors regulating circRNAs in the developing mouse brain are unknown. NOVA1 and NOVA2 are neural-enriched RNA-binding proteins with well-characterized roles in alternative splicing. Profiling of circRNAs from RNA-seq data revealed that global circRNA levels were reduced in embryonic cortex of Nova2 but not Nova1 knockout mice. Analysis of isolated inhibitory and excitatory cortical neurons lacking NOVA2 revealed an even more dramatic reduction of circRNAs and establishes a widespread role for NOVA2 in enhancing circRNA biogenesis. To investigate the cis-elements controlling NOVA2-regulation of circRNA biogenesis, we generated a backsplicing reporter based on the Efnb2 gene. We found that NOVA2-mediated backsplicing of circEfnb2 was impaired when YCAY clusters located in flanking introns were mutagenized. CLIP (cross-linking and immunoprecipitation) and additional reporter analyses demonstrated the importance of NOVA2 binding sites located in both flanking introns of circRNA loci. NOVA2 is the first RNA-binding protein identified to globally promote circRNA biogenesis in the developing brain.
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Affiliation(s)
- David Knupp
- Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Daphne A Cooper
- Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Yuhki Saito
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - Robert B Darnell
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - Pedro Miura
- Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
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11
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Humphrey J, Birsa N, Milioto C, McLaughlin M, Ule AM, Robaldo D, Eberle AB, Kräuchi R, Bentham M, Brown AL, Jarvis S, Bodo C, Garone M, Devoy A, Soraru G, Rosa A, Bozzoni I, Fisher EMC, Mühlemann O, Schiavo G, Ruepp MD, Isaacs AM, Plagnol V, Fratta P. FUS ALS-causative mutations impair FUS autoregulation and splicing factor networks through intron retention. Nucleic Acids Res 2020; 48:6889-6905. [PMID: 32479602 PMCID: PMC7337901 DOI: 10.1093/nar/gkaa410] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 04/21/2020] [Accepted: 05/06/2020] [Indexed: 12/12/2022] Open
Abstract
Mutations in the RNA-binding protein FUS cause amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease. FUS plays a role in numerous aspects of RNA metabolism, including mRNA splicing. However, the impact of ALS-causative mutations on splicing has not been fully characterized, as most disease models have been based on overexpressing mutant FUS, which will alter RNA processing due to FUS autoregulation. We and others have recently created knockin models that overcome the overexpression problem, and have generated high depth RNA-sequencing on FUS mutants in parallel to FUS knockout, allowing us to compare mutation-induced changes to genuine loss of function. We find that FUS-ALS mutations induce a widespread loss of function on expression and splicing. Specifically, we find that mutant FUS directly alters intron retention levels in RNA-binding proteins. Moreover, we identify an intron retention event in FUS itself that is associated with its autoregulation. Altered FUS levels have been linked to disease, and we show here that this novel autoregulation mechanism is altered by FUS mutations. Crucially, we also observe this phenomenon in other genetic forms of ALS, including those caused by TDP-43, VCP and SOD1 mutations, supporting the concept that multiple ALS genes interact in a regulatory network.
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Affiliation(s)
- Jack Humphrey
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UK Dementia Research Institute
- Department of Neurodegenerative Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Nicol Birsa
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UK Dementia Research Institute
| | - Carmelo Milioto
- UK Dementia Research Institute
- Department of Neurodegenerative Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Martha McLaughlin
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Agnieszka M Ule
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - David Robaldo
- UK Dementia Research Institute
- Department of Neurodegenerative Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Andrea B Eberle
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland
| | - Rahel Kräuchi
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland
| | - Matthew Bentham
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Anna-Leigh Brown
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Seth Jarvis
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UK Dementia Research Institute
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Cristian Bodo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | | | - Anny Devoy
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UK Dementia Research Institute
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London SE5 9RT, UK
| | - Gianni Soraru
- Department of Neurosciences, Università degli Studi di Padova, Padova 35121, Italy
| | - Alessandro Rosa
- Sapienza University of Rome, Rome 00185, Italy
- Center for Life Nano Science, Istituto Italiano di Tecnologia, Rome 00161, Italy
| | - Irene Bozzoni
- Sapienza University of Rome, Rome 00185, Italy
- Center for Life Nano Science, Istituto Italiano di Tecnologia, Rome 00161, Italy
| | - Elizabeth M C Fisher
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, Bern 3012, Switzerland
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- UK Dementia Research Institute
- Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, London WC1N 3BG, UK
| | - Marc-David Ruepp
- UK Dementia Research Institute
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London SE5 9RT, UK
| | - Adrian M Isaacs
- UK Dementia Research Institute
- Department of Neurodegenerative Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Vincent Plagnol
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Pietro Fratta
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
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12
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Meldolesi J. Alternative Splicing by NOVA Factors: From Gene Expression to Cell Physiology and Pathology. Int J Mol Sci 2020; 21:ijms21113941. [PMID: 32486302 PMCID: PMC7312376 DOI: 10.3390/ijms21113941] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/27/2020] [Accepted: 05/28/2020] [Indexed: 12/24/2022] Open
Abstract
NOVA1 and NOVA2, the two members of the NOVA family of alternative splicing factors, bind YCAY clusters of pre-mRNAs and assemble spliceosomes to induce the maintenance/removal of introns and exons, thus governing the development of mRNAs. Members of other splicing families operate analogously. Activity of NOVAs accounts for up to 700 alternative splicing events per cell, taking place both in the nucleus (co-transcription of mRNAs) and in the cytoplasm. Brain neurons express high levels of NOVAs, with NOVA1 predominant in cerebellum and spinal cord, NOVA2 in the cortex. Among brain physiological processes NOVAs play critical roles in axon pathfinding and spreading, structure and function of synapses, as well as the regulation of surface receptors and voltage-gated channels. In pathology, NOVAs contribute to neurodegenerative diseases and epilepsy. In vessel endothelial cells, NOVA2 is essential for angiogenesis, while in adipocytes, NOVA1 contributes to regulation of thermogenesis and obesity. In many cancers NOVA1 and also NOVA2, by interacting with specific miRNAs and by additional mechanisms, activate oncogenic roles promoting cell proliferation, colony formation, migration, and invasion. In conclusion, NOVAs regulate cell functions of physiological and pathological nature. Single cell identification and distinction, and new therapies addressed to NOVA targets might be developed in the near future.
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Affiliation(s)
- Jacopo Meldolesi
- Department of Neuroscience, San Raffaele Institute and San Raffaele University, via Olgettina 58, 20132 Milan, Italy
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13
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Dong X, Chen R. Understanding aberrant RNA splicing to facilitate cancer diagnosis and therapy. Oncogene 2019; 39:2231-2242. [PMID: 31819165 DOI: 10.1038/s41388-019-1138-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 11/22/2019] [Accepted: 11/27/2019] [Indexed: 12/31/2022]
Abstract
Almost all genes in normal cells undergo alternative RNA splicing to generate a greater extent of diversification of gene products for normal cellular functions. RNA splicing is tightly regulated and closely interplays with genetic and epigenetic machinery. While DNA polymorphism and somatic mutations modulate alternative splicing patterns, RNA splicing also controls genomic stability, chromatin organization, and transcriptome. Tumor cells, in turn, often take advantage of aberrant RNA splicing to develop, grow and progress into therapy-resistant tumors. Understanding alternative RNA splicing in tumor cells would, therefore, provide us opportunities to gain further insights into tumor biology, identify diagnostic or prognosis biomarkers, as well as to design effective therapeutic means to control tumor progression. Here, we provide an overview of RNA splicing mechanisms and use prostate cancer as an example to review recent advancements in our understanding of RNA splicing in cancer progression and therapy resistance. We also discuss emerging diagnostic and therapeutic potentials of RNA splicing events or RNA splicing factors.
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Affiliation(s)
- Xuesen Dong
- Department of Urologic Sciences, Faculty of Medicine, The University of British Columbia, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada. .,The Vancouver Prostate Centre, Vancouver General Hospital, 2660 Oak Street, Vancouver, BC, V6H 3Z6, Canada.
| | - Ruiqi Chen
- Faculty of Medicine, University of Toronto, 27 King's College Circle 8, Toronto, ON, M5S 1A1, Canada
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14
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Nussbacher JK, Tabet R, Yeo GW, Lagier-Tourenne C. Disruption of RNA Metabolism in Neurological Diseases and Emerging Therapeutic Interventions. Neuron 2019; 102:294-320. [PMID: 30998900 DOI: 10.1016/j.neuron.2019.03.014] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 01/24/2019] [Accepted: 03/12/2019] [Indexed: 02/06/2023]
Abstract
RNA binding proteins are critical to the maintenance of the transcriptome via controlled regulation of RNA processing and transport. Alterations of these proteins impact multiple steps of the RNA life cycle resulting in various molecular phenotypes such as aberrant RNA splicing, transport, and stability. Disruption of RNA binding proteins and widespread RNA processing defects are increasingly recognized as critical determinants of neurological diseases. Here, we describe distinct mechanisms by which the homeostasis of RNA binding proteins is compromised in neurological disorders through their reduced expression level, increased propensity to aggregate or sequestration by abnormal RNAs. These mechanisms all converge toward altered neuronal function highlighting the susceptibility of neurons to deleterious changes in RNA expression and the central role of RNA binding proteins in preserving neuronal integrity. Emerging therapeutic approaches to mitigate or reverse alterations of RNA binding proteins in neurological diseases are discussed.
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Affiliation(s)
- Julia K Nussbacher
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA, USA
| | - Ricardos Tabet
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; Broad Institute of Harvard University and MIT, Cambridge, MA 02142, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California, San Diego, La Jolla, CA, USA.
| | - Clotilde Lagier-Tourenne
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA; Broad Institute of Harvard University and MIT, Cambridge, MA 02142, USA.
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15
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Insights into Telomerase/hTERT Alternative Splicing Regulation Using Bioinformatics and Network Analysis in Cancer. Cancers (Basel) 2019; 11:cancers11050666. [PMID: 31091669 PMCID: PMC6562651 DOI: 10.3390/cancers11050666] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 01/08/2023] Open
Abstract
The reactivation of telomerase in cancer cells remains incompletely understood. The catalytic component of telomerase, hTERT, is thought to be the limiting component in cancer cells for the formation of active enzymes. hTERT gene expression is regulated at several levels including chromatin, DNA methylation, transcription factors, and RNA processing events. Of these regulatory events, RNA processing has received little attention until recently. RNA processing and alternative splicing regulation have been explored to understand how hTERT is regulated in cancer cells. The cis- and trans-acting factors that regulate the alternative splicing choice of hTERT in the reverse transcriptase domain have been investigated. Further, it was discovered that the splicing factors that promote the production of full-length hTERT were also involved in cancer cell growth and survival. The goals are to review telomerase regulation via alternative splicing and the function of hTERT splicing variants and to point out how bioinformatics approaches are leading the way in elucidating the networks that regulate hTERT splicing choice and ultimately cancer growth.
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16
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Saito Y, Yuan Y, Zucker-Scharff I, Fak JJ, Jereb S, Tajima Y, Licatalosi DD, Darnell RB. Differential NOVA2-Mediated Splicing in Excitatory and Inhibitory Neurons Regulates Cortical Development and Cerebellar Function. Neuron 2019; 101:707-720.e5. [PMID: 30638744 DOI: 10.1016/j.neuron.2018.12.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 09/25/2018] [Accepted: 12/12/2018] [Indexed: 01/13/2023]
Abstract
RNA-binding proteins (RBPs) regulate genetic diversity, but the degree to which they do so in individual cell types in vivo is unknown. We developed NOVA2 cTag-crosslinking and immunoprecipitation (CLIP) to generate functional RBP-RNA maps from different neuronal populations in the mouse brain. Combining cell type datasets from Nova2-cTag and Nova2 conditional knockout mice revealed differential NOVA2 regulatory actions on alternative splicing (AS) on the same transcripts expressed in different neurons. This includes functional differences in transcripts expressed in cortical and cerebellar excitatory versus inhibitory neurons, where we find NOVA2 is required for, respectively, development of laminar structure, motor coordination, and synapse formation. We also find that NOVA2-regulated AS is coupled to NOVA2 regulation of intron retention in hundreds of transcripts, which can sequester the trans-acting splicing factor PTBP2. In summary, cTag-CLIP complements single-cell RNA sequencing (RNA-seq) studies by providing a means for understanding RNA regulation of functional cell diversity.
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Affiliation(s)
- Yuhki Saito
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| | - Yuan Yuan
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Ilana Zucker-Scharff
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - John J Fak
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Saša Jereb
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Yoko Tajima
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Donny D Licatalosi
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Robert B Darnell
- Laboratory of Molecular Neuro-oncology and Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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17
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Ludlow AT, Wong MS, Robin JD, Batten K, Yuan L, Lai TP, Dahlson N, Zhang L, Mender I, Tedone E, Sayed ME, Wright WE, Shay JW. NOVA1 regulates hTERT splicing and cell growth in non-small cell lung cancer. Nat Commun 2018; 9:3112. [PMID: 30082712 PMCID: PMC6079032 DOI: 10.1038/s41467-018-05582-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing is dysregulated in cancer and the reactivation of telomerase involves the splicing of TERT transcripts to produce full-length (FL) TERT. Knowledge about the splicing factors that enhance or silence FL hTERT is lacking. We identified splicing factors that reduced telomerase activity and shortened telomeres using a siRNA minigene reporter screen and a lung cancer cell bioinformatics approach. A lead candidate, NOVA1, when knocked down resulted in a shift in hTERT splicing to non-catalytic isoforms, reduced telomerase activity, and progressive telomere shortening. NOVA1 knockdown also significantly altered cancer cell growth in vitro and in xenografts. Genome engineering experiments reveal that NOVA1 promotes the inclusion of exons in the reverse transcriptase domain of hTERT resulting in the production of FL hTERT transcripts. Utilizing hTERT splicing as a model splicing event in cancer may provide new insights into potentially targetable dysregulated splicing factors in cancer.
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Affiliation(s)
- Andrew T Ludlow
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA.
- School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI, 48109, USA.
| | - Mandy Sze Wong
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- Cold Spring Harbor Laboratories, One Bungtown Road, Cold Spring Harbor, New York, NY, 11724, USA
| | - Jerome D Robin
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- Aix-Marseille University, Marseille Medical Genetics (MMG), UMR125, Marseille, 13385, France
| | - Kimberly Batten
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Laura Yuan
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Tsung-Po Lai
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Nicole Dahlson
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Lu Zhang
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Ilgen Mender
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Enzo Tedone
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Mohammed E Sayed
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
- School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI, 48109, USA
| | - Woodring E Wright
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
| | - Jerry W Shay
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, 75390, USA
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18
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Su CH, D D, Tarn WY. Alternative Splicing in Neurogenesis and Brain Development. Front Mol Biosci 2018; 5:12. [PMID: 29484299 PMCID: PMC5816070 DOI: 10.3389/fmolb.2018.00012] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 01/25/2018] [Indexed: 12/20/2022] Open
Abstract
Alternative splicing of precursor mRNA is an important mechanism that increases transcriptomic and proteomic diversity and also post-transcriptionally regulates mRNA levels. Alternative splicing occurs at high frequency in brain tissues and contributes to every step of nervous system development, including cell-fate decisions, neuronal migration, axon guidance, and synaptogenesis. Genetic manipulation and RNA sequencing have provided insights into the molecular mechanisms underlying the effects of alternative splicing in stem cell self-renewal and neuronal fate specification. Timely expression and perhaps post-translational modification of neuron-specific splicing regulators play important roles in neuronal development. Alternative splicing of many key transcription regulators or epigenetic factors reprograms the transcriptome and hence contributes to stem cell fate determination. During neuronal differentiation, alternative splicing also modulates signaling activity, centriolar dynamics, and metabolic pathways. Moreover, alternative splicing impacts cortical lamination and neuronal development and function. In this review, we focus on recent progress toward understanding the contributions of alternative splicing to neurogenesis and brain development, which has shed light on how splicing defects may cause brain disorders and diseases.
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Affiliation(s)
- Chun-Hao Su
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Dhananjaya D
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
| | - Woan-Yuh Tarn
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
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19
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Weskamp K, Barmada SJ. TDP43 and RNA instability in amyotrophic lateral sclerosis. Brain Res 2018; 1693:67-74. [PMID: 29395044 DOI: 10.1016/j.brainres.2018.01.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/13/2022]
Abstract
The nuclear RNA-binding protein TDP43 is integrally involved in RNA processing. In accord with this central function, TDP43 levels are tightly regulated through a negative feedback loop, in which TDP43 recognizes its own RNA transcript, destabilizes it, and reduces new TDP43 protein production. In the neurodegenerative disorder amyotrophic lateral sclerosis (ALS), cytoplasmic mislocalization and accumulation of TDP43 disrupt autoregulation; conversely, inefficient TDP43 autoregulation can lead to cytoplasmic TDP43 deposition and subsequent neurodegeneration. Because TDP43 plays a multifaceted role in maintaining RNA metabolism, its mislocalization and accumulation interrupt several RNA processing pathways that in turn affect RNA stability and gene expression. TDP43-mediated disruption of these pathways-including alternative mRNA splicing, non-coding RNA processing, and RNA granule dynamics-may directly or indirectly contribute to ALS pathogenesis. Therefore, strategies that restore effective TDP43 autoregulation may ultimately prevent neurodegeneration in ALS and related disorders.
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Affiliation(s)
- Kaitlin Weskamp
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States
| | - Sami J Barmada
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States.
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20
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Jiang P, Hou Z, Bolin JM, Thomson JA, Stewart R. RNA-Seq of Human Neural Progenitor Cells Exposed to Lead (Pb) Reveals Transcriptome Dynamics, Splicing Alterations and Disease Risk Associations. Toxicol Sci 2017; 159:251-265. [PMID: 28903495 PMCID: PMC6372217 DOI: 10.1093/toxsci/kfx129] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Lead (Pb) is a well-known toxicant, especially for the developing nervous system, albeit the mechanism is largely unknown. In this study, we use time series RNA-seq to conduct a genome-wide survey of the transcriptome response of human embryonic stem cell-derived neural progenitor cells to lead treatment. Using a dynamic time warping algorithm coupled with statistical tests, we find that lead can either accelerate or decelerate the expression of specific genes during the time series. We further show that lead disrupts a neuron- and brain-specific splicing factor NOVA1 regulated splicing network. Using lead induced transcriptome change signatures, we predict several known and novel disease risks under lead exposure. The findings in this study will allow a better understanding of the mechanism of lead toxicity, facilitate the development of diagnostic biomarkers and treatment for lead exposure, and comprise a highly valuable resource for environmental toxicology. Our study also demonstrates that a human (embryonic stem) cell-derived system can be used for studying the mechanism of toxicants, which can be useful for drug or compound toxicity screens and safety assessment.
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Affiliation(s)
- Peng Jiang
- Regenerative Biology Laboratory, Morgridge Institute for Research, Madison, Wisconsin 53707
| | - Zhonggang Hou
- Regenerative Biology Laboratory, Morgridge Institute for Research, Madison, Wisconsin 53707
| | - Jennifer M. Bolin
- Regenerative Biology Laboratory, Morgridge Institute for Research, Madison, Wisconsin 53707
| | - James A. Thomson
- Regenerative Biology Laboratory, Morgridge Institute for Research, Madison, Wisconsin 53707
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, Wisconsin 53706
- Department of Molecular Cellular and Developmental Biology, University of California, Santa Barbara, California 93106
| | - Ron Stewart
- Regenerative Biology Laboratory, Morgridge Institute for Research, Madison, Wisconsin 53707
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21
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Li H, Lv B, Kong L, Xia J, Zhu M, Hu L, Zhen D, Wu Y, Jia X, Zhu S, Cui H. Nova1 mediates resistance of rat pheochromocytoma cells to hypoxia-induced apoptosis via the Bax/Bcl-2/caspase-3 pathway. Int J Mol Med 2017; 40:1125-1133. [PMID: 28791345 PMCID: PMC5593465 DOI: 10.3892/ijmm.2017.3089] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 07/26/2017] [Indexed: 11/18/2022] Open
Abstract
Neuro-oncological ventral antigen 1 (Nova1) is a well known brain-specific splicing factor. Several studies have identified Nova1 as a regulatory protein at the top of a hierarchical network. However, the function of Nova1 during hypoxia remains poorly understood. This study aimed to investigate the protective effect of Nova1 against cell hypoxia and to further explore the Bax/Bcl-2/caspase-3 pathway as a potential mechanism. During hypoxia, the survival rate of pheochromocytoma PC12 cells was gradually decreased and the apoptosis rate was gradually increased, peaking at 48 h of hypoxia. At 48 h after transfection of PC12 cells with pCMV-Myc-Nova1, the expression of Nova1 was significantly increased, with wide distribution in the cytoplasm and nucleus. Moreover, the survival rate was significantly increased and the apoptosis rate was significantly decreased. Additionally, the mRNA and protein expression levels of Bax and caspase-3 were significantly increased in the pCMV-Myc group and significantly decreased in the pCMV-Myc-Nova1 group, whereas that of Bcl-2 was significantly decreased in the pCMV-Myc group and significantly increased in the pCMV-Myc-Nova1 group. This study indicated that Nova1 could be linked to resistance to the hypoxia-induced apoptosis of PC12 cells via the Bax/Bcl-2/caspase-3 pathway, and this finding may be of significance for exploring novel mechanisms of hypoxia and the treatment of hypoxia-associated diseases.
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Affiliation(s)
- Hualing Li
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Bei Lv
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Ling Kong
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Jing Xia
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Ming Zhu
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Lijuan Hu
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Danyang Zhen
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Yifan Wu
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Xiaoqin Jia
- Department of Biochemistry, Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
| | - Sujuan Zhu
- Department of Biochemistry, Biosciences and Biotechnology College of Yangzhou University, Yangzhou, Jiangsu 225009, P.R. China
| | - Hengmi Cui
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou, Jiangsu 225001, P.R. China
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22
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Ramanouskaya TV, Grinev VV. The determinants of alternative RNA splicing in human cells. Mol Genet Genomics 2017; 292:1175-1195. [PMID: 28707092 DOI: 10.1007/s00438-017-1350-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 07/06/2017] [Indexed: 12/29/2022]
Abstract
Alternative splicing represents an important level of the regulation of gene function in eukaryotic organisms. It plays a critical role in virtually every biological process within an organism, including regulation of cell division and cell death, differentiation of tissues in the embryo and the adult organism, as well as in cellular response to diverse environmental factors. In turn, studies of the last decade have shown that alternative splicing itself is controlled by different mechanisms. Unfortunately, there is no clear understanding of how these diverse mechanisms, or determinants, regulate and constrain the set of alternative RNA species produced from any particular gene in every cell of the human body. Here, we provide a consolidated overview of alternative splicing determinants including RNA-protein interactions, epigenetic regulation via chromatin remodeling, coupling of transcription-to-alternative splicing, effect of secondary structures in pre-RNA, and function of the RNA quality control systems. We also extensively and critically discuss some mechanistic insights on coordinated inclusion/exclusion of exons during the formation of mature RNA molecules. We conclude that the final structure of RNA is pre-determined by a complex interplay between cis- and trans-acting factors. Altogether, currently available empirical data significantly expand our understanding of the functioning of the alternative splicing machinery of cells in normal and pathological conditions. On the other hand, there are still many blind spots that require further deep investigations.
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23
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Suzuki H, Matsuoka M. hnRNPA1 autoregulates its own mRNA expression to remain non-cytotoxic. Mol Cell Biochem 2016; 427:123-131. [PMID: 28000042 DOI: 10.1007/s11010-016-2904-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/03/2016] [Indexed: 01/03/2023]
Abstract
Heterogeneous nuclear ribonucleoprotein (hnRNP)A1, a member of the hnRNP family, is involved in a variety of RNA metabolisms. The hnRNPA1 expression is altered in some human diseases and mutations of the hnRNPA1 gene cause amyotrophic lateral sclerosis and multisystem proteinopathy. It has been therefore assumed that the dysregulation of hnRNPA1 is linked to the pathogenesis of the diseases. However, the mechanism underlying the regulation of the hnRNPA1 expression remains unknown. In this study, using cell-based models, we have found that hnRNPA1 negatively regulates its own mRNA expression by inhibiting the intron10 splicing of hnRNPA1 pre-mRNA. This mechanism likely serves as an autoregulation of the hnRNPA1 expression. We have also found that a low-grade excess of hnRNPA1 expression causes cytotoxicity by activating the mitochondrial apoptosis pathway. Collectively, these data suggest that the level of hnRNPA1 is strictly controlled to be within a certain range by the mRNA autoregulation in the physiological condition so that the cytotoxicity-causative alteration of hnRNPA1 expression does not take place.
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Affiliation(s)
- Hiroaki Suzuki
- Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-Ku, Tokyo, 160-8402, Japan
| | - Masaaki Matsuoka
- Department of Pharmacology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-Ku, Tokyo, 160-8402, Japan. .,Department of Dermatological Neuroscience, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-Ku, Tokyo, 160-8402, Japan.
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24
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Abstract
Alternative precursor-mRNA splicing is a key mechanism for regulating gene expression in mammals and is controlled by specialized RNA-binding proteins. The misregulation of splicing is implicated in multiple neurological disorders. We describe recent mouse genetic studies of alternative splicing that reveal its critical role in both neuronal development and the function of mature neurons. We discuss the challenges in understanding the extensive genetic programmes controlled by proteins that regulate splicing, both during development and in the adult brain.
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Affiliation(s)
- Celine K Vuong
- Molecular Biology Interdepartmental Graduate Program, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Douglas L Black
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Sika Zheng
- Division of Biomedical Sciences, University of California at Riverside, Riverside, California 92521, USA
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25
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Lin JC, Chi YL, Peng HY, Lu YH. RBM4-Nova1-SRSF6 splicing cascade modulates the development of brown adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1368-1379. [PMID: 27535496 DOI: 10.1016/j.bbagrm.2016.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/13/2016] [Accepted: 08/09/2016] [Indexed: 01/01/2023]
Abstract
Alternative splicing (AS) is a pivotal mechanism for the expansion of gene diversity, which determines the cellular fate or specification. However, the effect of AS networks on brown adipogenesis has not been comprehensively investigated. In this study, we identified the discriminative splicing profiles of RNA-binding motif protein 4a-knockout (RBM4a-/-) brown adipocytes (BAs) and compared them with those of their wild-type counterparts through deep RNA-sequencing. Among these candidates, RBM4a ablation enhanced the relative level of exon 4-excluded neuro-oncological ventral antigen 1 (Nova1-4) transcripts, which were predominantly generated in embryonic BAs. By contrast, most of the Nova1 transcripts were exon 4-included (Nova1+4) in mature BAs. The Nova1 isoforms exhibited differential effects on repressing the development of BAs. Moreover, overexpression of Nova1 proteins reduced the serine/arginine splicing factor 6 (SRSF6) level by enhancing the generation of intron 2-included (SRSF6+intron 2) transcripts, which are a putative candidate of the AS-coupled nonsense-mediated decay mechanism. Furthermore, we observed the positive effect of SRSF6 on BA development. These results highlight the hierarchical role of RBM4a in an AS cascade that manipulates brown adipogenesis.
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Affiliation(s)
- Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
| | - Yi-Lin Chi
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Hui-Yu Peng
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yi-Han Lu
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
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26
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Prasad A, Porter DF, Kroll-Conner PL, Mohanty I, Ryan AR, Crittenden SL, Wickens M, Kimble J. The PUF binding landscape in metazoan germ cells. RNA (NEW YORK, N.Y.) 2016; 22:1026-43. [PMID: 27165521 PMCID: PMC4911911 DOI: 10.1261/rna.055871.116] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 04/14/2016] [Indexed: 05/09/2023]
Abstract
PUF (Pumilio/FBF) proteins are RNA-binding proteins and conserved stem cell regulators. The Caenorhabditis elegans PUF proteins FBF-1 and FBF-2 (collectively FBF) regulate mRNAs in germ cells. Without FBF, adult germlines lose all stem cells. A major gap in our understanding of PUF proteins, including FBF, is a global view of their binding sites in their native context (i.e., their "binding landscape"). To understand the interactions underlying FBF function, we used iCLIP (individual-nucleotide resolution UV crosslinking and immunoprecipitation) to determine binding landscapes of C. elegans FBF-1 and FBF-2 in the germline tissue of intact animals. Multiple iCLIP peak-calling methods were compared to maximize identification of both established FBF binding sites and positive control target mRNAs in our iCLIP data. We discovered that FBF-1 and FBF-2 bind to RNAs through canonical as well as alternate motifs. We also analyzed crosslinking-induced mutations to map binding sites precisely and to identify key nucleotides that may be critical for FBF-RNA interactions. FBF-1 and FBF-2 can bind sites in the 5'UTR, coding region, or 3'UTR, but have a strong bias for the 3' end of transcripts. FBF-1 and FBF-2 have strongly overlapping target profiles, including mRNAs and noncoding RNAs. From a statistically robust list of 1404 common FBF targets, 847 were previously unknown, 154 were related to cell cycle regulation, three were lincRNAs, and 335 were shared with the human PUF protein PUM2.
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Affiliation(s)
- Aman Prasad
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Douglas F Porter
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Peggy L Kroll-Conner
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Ipsita Mohanty
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Anne R Ryan
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Sarah L Crittenden
- Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Marvin Wickens
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Judith Kimble
- Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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27
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Saito Y, Miranda-Rottmann S, Ruggiu M, Park CY, Fak JJ, Zhong R, Duncan JS, Fabella BA, Junge HJ, Chen Z, Araya R, Fritzsch B, Hudspeth AJ, Darnell RB. NOVA2-mediated RNA regulation is required for axonal pathfinding during development. eLife 2016; 5. [PMID: 27223325 PMCID: PMC4930328 DOI: 10.7554/elife.14371] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 05/23/2016] [Indexed: 01/13/2023] Open
Abstract
The neuron specific RNA-binding proteins NOVA1 and NOVA2 are highly homologous alternative splicing regulators. NOVA proteins regulate at least 700 alternative splicing events in vivo, yet relatively little is known about the biologic consequences of NOVA action and in particular about functional differences between NOVA1 and NOVA2. Transcriptome-wide searches for isoform-specific functions, using NOVA1 and NOVA2 specific HITS-CLIP and RNA-seq data from mouse cortex lacking either NOVA isoform, reveals that NOVA2 uniquely regulates alternative splicing events of a series of axon guidance related genes during cortical development. Corresponding axonal pathfinding defects were specific to NOVA2 deficiency: Nova2-/- but not Nova1-/- mice had agenesis of the corpus callosum, and axonal outgrowth defects specific to ventral motoneuron axons and efferent innervation of the cochlea. Thus we have discovered that NOVA2 uniquely regulates alternative splicing of a coordinate set of transcripts encoding key components in cortical, brainstem and spinal axon guidance/outgrowth pathways during neural differentiation, with severe functional consequences in vivo.
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Affiliation(s)
- Yuhki Saito
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Soledad Miranda-Rottmann
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Matteo Ruggiu
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | | | - John J Fak
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Ru Zhong
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Jeremy S Duncan
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, United States
| | - Brian A Fabella
- Laboratory of Sensory Neuroscience, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Harald J Junge
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Zhe Chen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, United States
| | - Roberto Araya
- Department of Neurosciences, Faculty of Medicine, University of Montreal, Montreal, Canada
| | - Bernd Fritzsch
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, United States
| | - A J Hudspeth
- Laboratory of Sensory Neuroscience, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Robert B Darnell
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, United States.,New York Genome Center, New York, United States
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28
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Takei S, Togo-Ohno M, Suzuki Y, Kuroyanagi H. Evolutionarily conserved autoregulation of alternative pre-mRNA splicing by ribosomal protein L10a. Nucleic Acids Res 2016; 44:5585-5596. [PMID: 26961311 PMCID: PMC4937301 DOI: 10.1093/nar/gkw152] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Alternative splicing of pre-mRNAs can regulate expression of protein-coding genes by generating unproductive mRNAs rapidly degraded by nonsense-mediated mRNA decay (NMD). Many of the genes directly regulated by alternative splicing coupled with NMD (AS-NMD) are related to RNA metabolism, but the repertoire of genes regulated by AS-NMD in vivo is to be determined. Here, we analyzed transcriptome data of wild-type and NMD-defective mutant strains of the nematode worm Caenorhabditis elegans and demonstrate that eight of the 82 cytoplasmic ribosomal protein (rp) genes generate unproductively spliced mRNAs. Knockdown of any of the eight rp genes exerted a dynamic and compensatory effect on alternative splicing of its own transcript and inverse effects on that of the other rp genes. A large subunit protein L10a, termed RPL-1 in nematodes, directly and specifically binds to an evolutionarily conserved 39-nt stretch termed L10ARE between the two alternative 5′ splice sites in its own pre-mRNA to switch the splice site choice. Furthermore, L10ARE-mediated splicing autoregulation of the L10a-coding gene is conserved in vertebrates. These results indicate that L10a is an evolutionarily conserved splicing regulator and that homeostasis of a subset of the rp genes are regulated at the level of pre-mRNA splicing in vivo.
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Affiliation(s)
- Satomi Takei
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Marina Togo-Ohno
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
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29
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Zhi F, Wang Q, Deng D, Shao N, Wang R, Xue L, Wang S, Xia X, Yang Y. MiR-181b-5p downregulates NOVA1 to suppress proliferation, migration and invasion and promote apoptosis in astrocytoma. PLoS One 2014; 9:e109124. [PMID: 25299073 PMCID: PMC4192361 DOI: 10.1371/journal.pone.0109124] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 08/28/2014] [Indexed: 11/30/2022] Open
Abstract
MicroRNAs (miRNAs) are small, short noncoding RNAs that modulate the expression of numerous genes by targeting their mRNA. Numerous abnormal miRNA expression patterns are observed in various human malignancies, and certain miRNAs can act as oncogenes or tumor suppressors. Astrocytoma, the most common neuroepithelial cancer, represents the majority of malignant brain tumors in humans. In our previous studies, we found that the downregulation of miR-181b-5p in astrocytomas is associated with a poor prognosis. The aim of the present study was to investigate the functional role of miR-181b-5p and its possible target genes. miR-181b-5p was significantly downregulated in astrocytoma specimens, and the reduced expression of miR-181b-5p was inversely correlated with the clinical stage. The ectopic expression of miR-181b-5p inhibited proliferation, migration and invasion and induced apoptosis in astrocytoma cancer cells in vitro. The NOVA1 (neuro-oncological ventral antigen 1) gene was further identified as a novel direct target of miR-181b-5p. Specifically, miR-181b-5p bound directly to the 3'-untranslated region (UTR) of NOVA1 and suppressed its expression. In clinical specimens, NOVA1 was overexpressed, and its protein levels were inversely correlated with miR-181b-5p expression. Furthermore, the changing level of NOVA1 was significantly associated with a poor survival outcome. Similar to restoring miR-181b-5p expression, downregulating NOVA1 inhibited cell growth, migration and invasion. Overexpression of NOVA1 reversed the inhibitory effects of miR-181b-5p. Our results indicate that miR-181b-5p is a tumor suppressor in astrocytoma that inhibits tumor progression by targeting NOVA1. These findings suggest that miR-181b-5p may serve as a novel therapeutic target for astrocytoma.
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Affiliation(s)
- Feng Zhi
- Modern Medical Research Center, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Qiang Wang
- Department of Neurosurgery, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Danni Deng
- Modern Medical Research Center, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Naiyuan Shao
- Department of Neurosurgery, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Rong Wang
- Modern Medical Research Center, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Lian Xue
- Modern Medical Research Center, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Suinuan Wang
- Department of Neurosurgery, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Xiwei Xia
- Department of Neurosurgery, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Yilin Yang
- Modern Medical Research Center, Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
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30
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Villate O, Turatsinze JV, Mascali LG, Grieco FA, Nogueira TC, Cunha DA, Nardelli TR, Sammeth M, Salunkhe VA, Esguerra JLS, Eliasson L, Marselli L, Marchetti P, Eizirik DL. Nova1 is a master regulator of alternative splicing in pancreatic beta cells. Nucleic Acids Res 2014; 42:11818-30. [PMID: 25249621 PMCID: PMC4191425 DOI: 10.1093/nar/gku861] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Alternative splicing (AS) is a fundamental mechanism for the regulation of gene expression. It affects more than 90% of human genes but its role in the regulation of pancreatic beta cells, the producers of insulin, remains unknown. Our recently published data indicated that the ‘neuron-specific’ Nova1 splicing factor is expressed in pancreatic beta cells. We have presently coupled specific knockdown (KD) of Nova1 with RNA-sequencing to determine all splice variants and downstream pathways regulated by this protein in beta cells. Nova1 KD altered the splicing of nearly 5000 transcripts. Pathway analysis indicated that these genes are involved in exocytosis, apoptosis, insulin receptor signaling, splicing and transcription. In line with these findings, Nova1 silencing inhibited insulin secretion and induced apoptosis basally and after cytokine treatment in rodent and human beta cells. These observations identify a novel layer of regulation of beta cell function, namely AS controlled by key splicing regulators such as Nova1.
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Affiliation(s)
- Olatz Villate
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Jean-Valery Turatsinze
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Loriana G Mascali
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Fabio A Grieco
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Tatiane C Nogueira
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Daniel A Cunha
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Tarlliza R Nardelli
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Michael Sammeth
- Laboratório Nacional de Computação Científica (LNCC), Petrópolis Rio de Janeiro, 25651-076, Brazil
| | - Vishal A Salunkhe
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Jonathan L S Esguerra
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Lena Eliasson
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Lorella Marselli
- Department of Clinical and Experimental Medicine, Pancreatic Islet Cell Laboratory, University of Pisa, Pisa, 56126, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Pancreatic Islet Cell Laboratory, University of Pisa, Pisa, 56126, Italy
| | - Decio L Eizirik
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
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31
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Chen B, Yun J, Kim MS, Mendell JT, Xie Y. PIPE-CLIP: a comprehensive online tool for CLIP-seq data analysis. Genome Biol 2014; 15:R18. [PMID: 24451213 PMCID: PMC4054095 DOI: 10.1186/gb-2014-15-1-r18] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 01/22/2014] [Indexed: 11/10/2022] Open
Abstract
CLIP-seq is widely used to study genome-wide interactions between RNA-binding proteins and RNAs. However, there are few tools available to analyze CLIP-seq data, thus creating a bottleneck to the implementation of this methodology. Here, we present PIPE-CLIP, a Galaxy framework-based comprehensive online pipeline for reliable analysis of data generated by three types of CLIP-seq protocol: HITS-CLIP, PAR-CLIP and iCLIP. PIPE-CLIP provides both data processing and statistical analysis to determine candidate cross-linking regions, which are comparable to those regions identified from the original studies or using existing computational tools. PIPE-CLIP is available at http://pipeclip.qbrc.org/.
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32
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Zaghlool A, Ameur A, Cavelier L, Feuk L. Splicing in the human brain. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 116:95-125. [PMID: 25172473 DOI: 10.1016/b978-0-12-801105-8.00005-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It has become increasingly clear over the past decade that RNA has important functions in human cells beyond its role as an intermediate translator of DNA to protein. It is now known that RNA plays highly specific roles in pathways involved in regulatory, structural, and catalytic functions. The complexity of RNA production and regulation has become evident with the advent of high-throughput methods to study the transcriptome. Deep sequencing has revealed an enormous diversity of RNA types and transcript isoforms in human cells. The transcriptome of the human brain is particularly interesting as it contains more expressed genes than other tissues and also displays an extreme diversity of transcript isoforms, indicating that highly complex regulatory pathways are present in the brain. Several of these regulatory proteins are now identified, including RNA-binding proteins that are neuron specific. RNA-binding proteins also play important roles in regulating the splicing process and the temporal and spatial isoform production. While significant progress has been made in understanding the human transcriptome, many questions still remain regarding the basic mechanisms of splicing and subcellular localization of RNA. A long-standing question is to what extent the splicing of pre-mRNA is cotranscriptional and posttranscriptional, respectively. Recent data, including studies of the human brain, indicate that splicing is primarily cotranscriptional in human cells. This chapter describes the current understanding of splicing and splicing regulation in the human brain and discusses the recent global sequence-based analyses of transcription and splicing.
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Affiliation(s)
- Ammar Zaghlool
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Adam Ameur
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lucia Cavelier
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Uppsala University Hospital, Uppsala, Sweden
| | - Lars Feuk
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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33
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Morchikh M, Naughtin M, Di Nunzio F, Xavier J, Charneau P, Jacob Y, Lavigne M. TOX4 and NOVA1 proteins are partners of the LEDGF PWWP domain and affect HIV-1 replication. PLoS One 2013; 8:e81217. [PMID: 24312278 PMCID: PMC3842248 DOI: 10.1371/journal.pone.0081217] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 10/10/2013] [Indexed: 12/31/2022] Open
Abstract
PWWP domains are involved in the chromatin attachment of several proteins. They bind to both DNA and proteins and their interaction with specific histone methylation marks define them as a new class of histone code readers. The lens epithelium derived growth factor (LEDGF/p75) contains an N-terminal PWWP domain necessary for its interaction with chromatin but also a C-terminal domain which interacts with several proteins, such as lentiviral integrases. These two domains confer a chromatin-tethering function to LEDGF/p75 and in the case of lentiviral integrases, this tethering participates in the efficiency and site selectivity of integration. Although proteins interacting with LEDGF/p75 C-terminal domain have been extensively studied, no data exist about partners of its PWWP domain regulating its interaction with chromatin. In this study, we report the identification by yeast-two-hybrid of thirteen potential partners of the LEDGF PWWP domain. Five of these interactions were confirmed in mammalian cells, using both a protein complementation assay and co-immunoprecipitation approaches. Three of these partners interact with full length LEDGF/p75, they are specific for PWWP domains of the HDGF family and they require PWWP amino acids essential for the interaction with chromatin. Among them, the transcription activator TOX4 and the splicing cofactor NOVA1 were selected for a more extensive study. These two proteins or their PWWP interacting regions (PIR) colocalize with LEDGF/p75 in Hela cells and interact in vitro in the presence of DNA. Finally, single round VSV-G pseudotyped HIV-1 but not MLV infection is inhibited in cells overexpressing these two PIRs. The observed inhibition of infection can be attributed to a defect in the integration step. Our data suggest that a regulation of LEDGF interaction with chromatin by cellular partners of its PWWP domain could be involved in several processes linked to LEDGF tethering properties, such as lentiviral integration, DNA repair or transcriptional regulation.
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Affiliation(s)
- Mehdi Morchikh
- Ecole Normale Supérieure, Laboratoire Joliot-Curie, Centre National de la Recherche Scientifique, Lyon, France
- Institut Pasteur, Unité de Virologie Structurale, Centre National de la Recherche Scientifique, Unité de recherche associée, Paris, France
- Université Pierre et Marie Curie, Paris, France
| | - Monica Naughtin
- Ecole Normale Supérieure, Laboratoire Joliot-Curie, Centre National de la Recherche Scientifique, Lyon, France
| | - Francesca Di Nunzio
- Institut Pasteur, Unité de Virologie Moléculaire et Vaccinologie, Centre National de la Recherche Scientifique, Paris, France
| | - Johan Xavier
- Ecole Normale Supérieure, Laboratoire Joliot-Curie, Centre National de la Recherche Scientifique, Lyon, France
| | - Pierre Charneau
- Institut Pasteur, Unité de Virologie Moléculaire et Vaccinologie, Centre National de la Recherche Scientifique, Paris, France
| | - Yves Jacob
- Institut Pasteur, Unité de Génétique Moléculaire des Virus à ARN, Centre National de la Recherche Scientifique, Paris, France
- Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Marc Lavigne
- Ecole Normale Supérieure, Laboratoire Joliot-Curie, Centre National de la Recherche Scientifique, Lyon, France
- Institut Pasteur, Unité de Virologie Structurale, Centre National de la Recherche Scientifique, Unité de recherche associée, Paris, France
- * E-mail:
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Zhou Y, Liu S, Liu G, Öztürk A, Hicks GG. ALS-associated FUS mutations result in compromised FUS alternative splicing and autoregulation. PLoS Genet 2013; 9:e1003895. [PMID: 24204307 PMCID: PMC3814325 DOI: 10.1371/journal.pgen.1003895] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 09/05/2013] [Indexed: 12/13/2022] Open
Abstract
The gene encoding a DNA/RNA binding protein FUS/TLS is frequently mutated in amyotrophic lateral sclerosis (ALS). Mutations commonly affect its carboxy-terminal nuclear localization signal, resulting in varying deficiencies of FUS nuclear localization and abnormal cytoplasmic accumulation. Increasing evidence suggests deficiencies in FUS nuclear function may contribute to neuron degeneration. Here we report a novel FUS autoregulatory mechanism and its deficiency in ALS-associated mutants. Using FUS CLIP-seq, we identified significant FUS binding to a highly conserved region of exon 7 and the flanking introns of its own pre-mRNAs. We demonstrated that FUS is a repressor of exon 7 splicing and that the exon 7-skipped splice variant is subject to nonsense-mediated decay (NMD). Overexpression of FUS led to the repression of exon 7 splicing and a reduction of endogenous FUS protein. Conversely, the repression of exon 7 was reduced by knockdown of FUS protein, and moreover, it was rescued by expression of EGFP-FUS. This dynamic regulation of alternative splicing describes a novel mechanism of FUS autoregulation. Given that ALS-associated FUS mutants are deficient in nuclear localization, we examined whether cells expressing these mutants would be deficient in repressing exon 7 splicing. We showed that FUS harbouring R521G, R522G or ΔExon15 mutation (minor, moderate or severe cytoplasmic localization, respectively) directly correlated with respectively increasing deficiencies in both exon 7 repression and autoregulation of its own protein levels. These data suggest that compromised FUS autoregulation can directly exacerbate the pathogenic accumulation of cytoplasmic FUS protein in ALS. We showed that exon 7 skipping can be induced by antisense oligonucleotides targeting its flanking splice sites, indicating the potential to alleviate abnormal cytoplasmic FUS accumulation in ALS. Taken together, FUS autoregulation by alternative splicing provides insight into a molecular mechanism by which FUS-regulated pre-mRNA processing can impact a significant number of targets important to neurodegeneration.
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Affiliation(s)
- Yueqin Zhou
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- Regenerative Medicine Program, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Songyan Liu
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- Regenerative Medicine Program, University of Manitoba, Winnipeg, Manitoba, Canada
- Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Guodong Liu
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- Regenerative Medicine Program, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Arzu Öztürk
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- Regenerative Medicine Program, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Geoffrey G. Hicks
- Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
- Regenerative Medicine Program, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Zhang C, Lee KY, Swanson MS, Darnell RB. Prediction of clustered RNA-binding protein motif sites in the mammalian genome. Nucleic Acids Res 2013; 41:6793-807. [PMID: 23685613 PMCID: PMC3737533 DOI: 10.1093/nar/gkt421] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 01/24/2023] Open
Abstract
Sequence-specific interactions of RNA-binding proteins (RBPs) with their target transcripts are essential for post-transcriptional gene expression regulation in mammals. However, accurate prediction of RBP motif sites has been difficult because many RBPs recognize short and degenerate sequences. Here we describe a hidden Markov model (HMM)-based algorithm mCarts to predict clustered functional RBP-binding sites by effectively integrating the number and spacing of individual motif sites, their accessibility in local RNA secondary structures and cross-species conservation. This algorithm learns and quantifies rules of these features, taking advantage of a large number of in vivo RBP-binding sites obtained from cross-linking and immunoprecipitation data. We applied this algorithm to study two representative RBP families, Nova and Mbnl, which regulate tissue-specific alternative splicing through interacting with clustered YCAY and YGCY elements, respectively, and predicted their binding sites in the mouse transcriptome. Despite the low information content in individual motif elements, our algorithm made specific predictions for successful experimental validation. Analysis of predicted sites also revealed cases of extensive and distal RBP-binding sites important for splicing regulation. This algorithm can be readily applied to other RBPs to infer their RNA-regulatory networks. The software is freely available at http://zhanglab.c2b2.columbia.edu/index.php/MCarts.
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Affiliation(s)
- Chaolin Zhang
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA, Department of Molecular Genetics and Microbiology and the Center for NeuroGenetics, University of Florida, College of Medicine, Gainesville, FL 32610, USA and Department of Neurology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
| | - Kuang-Yung Lee
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA, Department of Molecular Genetics and Microbiology and the Center for NeuroGenetics, University of Florida, College of Medicine, Gainesville, FL 32610, USA and Department of Neurology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
| | - Maurice S. Swanson
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA, Department of Molecular Genetics and Microbiology and the Center for NeuroGenetics, University of Florida, College of Medicine, Gainesville, FL 32610, USA and Department of Neurology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
| | - Robert B. Darnell
- Laboratory of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA, Department of Molecular Genetics and Microbiology and the Center for NeuroGenetics, University of Florida, College of Medicine, Gainesville, FL 32610, USA and Department of Neurology, Chang Gung Memorial Hospital, Keelung 204, Taiwan
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Grinev VV, Ramanouskaya TV, Gloushen SV. Multidimensional control of cell structural robustness. Cell Biol Int 2013; 37:1023-37. [PMID: 23686647 DOI: 10.1002/cbin.10128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Accepted: 04/21/2013] [Indexed: 11/12/2022]
Abstract
Ample adaptive and functional opportunities of a living cell are determined by the complexity of its structural organisation. However, such complexity gives rise to a problem of maintenance of the coherence of inner processes in macroscopic interims and in macroscopic volumes which is necessary to support the structural robustness of a cell. The solution to this problem lies in multidimensional control of the adaptive and functional changes of a cell as well as its self-renewing processes in the context of environmental conditions. Six mechanisms (principles) form the basis of this multidimensional control: regulatory circuits with feedback loops, redundant inner diversity within a cell, multilevel distributed network organisation of a cell, molecular selection within a cell, continuous informational flows and functioning with a reserve of power. In the review we provide detailed analysis of these mechanisms, discuss their specific functions and the role of the superposition of these mechanisms in the maintenance of cell structural robustness in a wide range of environmental conditions.
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Affiliation(s)
- Vasily V Grinev
- Biology Faculty, Department of Genetics, Belarusian State University, 220030, Minsk, Belarus.
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Abstract
Neurons have their own systems for regulating RNA. Several multigene families encode RNA binding proteins (RNABPs) that are uniquely expressed in neurons, including the well-known neuron-specific markers ELAV and NeuN and the disease antigen NOVA. New technologies have emerged in recent years to assess the function of these proteins in vivo, and the answers are yielding insights into how and why neurons may regulate RNA in special ways-to increase cellular complexity, to localize messenger RNA (mRNA) spatially, and to regulate their expression in response to synaptic stimuli. The functions of such restricted neuronal proteins are likely to be complemented by more widely expressed RNABPs that may themselves have developed specialized functions in neurons, including Argonaute/microRNAs (miRNAs). Here we review what is known about such RNABPs and explore the potential biologic and neurologic significance of neuronal RNA regulatory systems.
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Affiliation(s)
- Robert B Darnell
- Department of Molecular Neuro-Oncology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
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38
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Fu RH, Liu SP, Huang SJ, Chen HJ, Chen PR, Lin YH, Ho YC, Chang WL, Tsai CH, Shyu WC, Lin SZ. Aberrant Alternative Splicing Events in Parkinson's Disease. Cell Transplant 2013; 22:653-61. [PMID: 23127794 DOI: 10.3727/096368912x655154] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing (AS) using a sole gene to express multiple transcripts with diverse protein coding sequences and/or RNA regulatory elements raises genomic complexities. In the nervous system, several thousand AS events play important roles in ion transportation, receptor recognition, neurotransmission, memory, and learning. Not surprisingly, AS influences human physiology, development, and disease. Many research studies have focused on aberrant AS in nervous system diseases, including Parkinson's disease (PD), the second most common progressive neurodegenerative disorder of the central nervous system. PD affects the lives of several million people globally. It is caused by protein aggregation, such as in Lewy bodies, and the loss of dopamine-containing neurons in the substantia nigra of the midbrain. To our knowledge, six genes, including PARK2, SNCAIP, LRRK2, SNCA, SRRM2, and MAPT, are involved in aberrant AS events in PD patients. In this review, we highlight the relevance of aberrant AS in PD and discuss the use of an aberrant AS profile as a potential diagnostic or prognostic marker for PD and as a possible means of applying therapy.
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Affiliation(s)
- Ru-Huei Fu
- Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan, ROC
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Shih-Ping Liu
- Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan, ROC
- Graduate Institute of Basic Medical Science, China Medical University, Taichung, Taiwan, ROC
| | - Shyh-Jer Huang
- Center for Molecular Medicine, China Medical University Hospital, Taichung, Taiwan, ROC
| | - Hung-Jen Chen
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, China Medical University Hospital, Taichung, Taiwan, ROC
| | - Pin-Ru Chen
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Ya-Hsien Lin
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Yu-Chen Ho
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Wen-Lin Chang
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Chang-Hai Tsai
- Department of Pediatrics, China Medical University Hospital, Taichung, Taiwan, ROC
- Department of Healthcare Administration, Asia University, Taichung, Taiwan, ROC
| | - Woei-Cherng Shyu
- Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan, ROC
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
| | - Shinn-Zong Lin
- Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan, ROC
- Graduate Institute of Immunology, China Medical University, Taichung, Taiwan, ROC
- Department of Healthcare Administration, Asia University, Taichung, Taiwan, ROC
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Eom T, Zhang C, Wang H, Lay K, Fak J, Noebels JL, Darnell RB. NOVA-dependent regulation of cryptic NMD exons controls synaptic protein levels after seizure. eLife 2013; 2:e00178. [PMID: 23359859 PMCID: PMC3552424 DOI: 10.7554/elife.00178] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/29/2012] [Indexed: 12/13/2022] Open
Abstract
The neuronal RNA binding protein NOVA regulates splicing, shuttles to the cytoplasm, and co-localizes with target transcripts in dendrites, suggesting links between splicing and local translation. Here we identified >200 transcripts showing NOVA-dependent changes in abundance, but, surprisingly, HITS-CLIP revealed NOVA binds these RNAs in introns rather than 3′ UTRs. This led us to discover NOVA-regulated splicing of cryptic exons within these introns. These exons triggered nonsense mediated decay (NMD), as UPF1 and protein synthesis were required for NOVA's effect on RNA levels. Their regulation was dynamic and physiologically relevant. The NMD exons were regulated by seizures, which also induced changes in Nova subcellular localization and mediated large changes in synaptic proteins, including proteins implicated in familial epilepsy. Moreover, Nova haploinsufficient mice had spontaneous epilepsy. The data reveal a hidden means of dynamic RNA regulation linking electrical activity to splicing and protein output, and of mediating homeostatic excitation/inhibition balance in neurons. DOI:http://dx.doi.org/10.7554/eLife.00178.001 After the DNA in a gene has been transcribed into messenger RNA, portions of the mRNA called introns are removed, and the remaining stretches of mRNA, which are known as exons, are spliced together. Within eukaryotic cells, a process known as alternative splicing allows a single gene to encode for multiple protein variants by ensuring that some exons are included in the final, modified mRNA, while other exons are excluded. This modified mRNA is then translated into proteins. Eukaryotic cells also contain proteins that bind to RNA to regulate alternative splicing. These RNA-binding proteins are often found in both the cytoplasm and nucleus of cells, and their involvement in splicing may be linked to other processes in the cell such as mRNA localization and translation. It has also become clear over the past two decades that certain types of RNA-binding proteins, including NOVA proteins, are only found in neurons, and that these proteins have been best characterized as alternative splicing regulators. Recent work has also suggested that they also have important roles in regulating neuronal activity and development, and that their actions in neuronal nuclei and cytoplasm might be coordinated. Now Eom et al. use the predictive power of a high throughput sequencing and crosslinking method termed HITS-CLIP to show that NOVA proteins can indirectly regulate cytoplasmic mRNA levels by regulating the process of alternative splicing in the nucleus to produce ‘cryptic’ exons in the brains of mice. The presence of these exons in the mRNA leads to the production of premature termination codons in the cytoplasm. These codons trigger a process called nonsense-mediated decay that involves identifying mRNA transcripts that contain nonsense mutations, and then degrading them. These cryptic exons were seen in mice missing the NOVA proteins, where they are expressed in abnormally high levels; in normal mice, these exons have not been seen before, hence they were termed ‘cryptic’. Eom et al. also show that these cryptic exons are physiologically relevant by inducing epileptic seizures in mice. Following the seizures, they find that the NOVA proteins up-regulate and down-regulate the levels of different cryptic exons, leading to changes in the levels of the proteins encoded by these mRNAs, including proteins that inhibit further seizures. Overall the results indicate that, by controlling the production of various proteins in neurons, these previously unknown cryptic exons have important roles in the workings of the brain. DOI:http://dx.doi.org/10.7554/eLife.00178.002
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Affiliation(s)
- Taesun Eom
- Laboratory of Molecular Neuro-Oncology , Rockefeller University , New York , United States
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Lawson CB, Niino T, Hermansen RA, Brok-Volchanskaya V, Jackson MF, Garikipati DK, Liberles DA, Rodgers BD. The salmonid myostatin gene family: a novel model for investigating mechanisms that influence duplicate gene fate. BMC Evol Biol 2012; 12:202. [PMID: 23043301 PMCID: PMC3557186 DOI: 10.1186/1471-2148-12-202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/22/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Most fishes possess two paralogs for myostatin, a muscle growth inhibitor, while salmonids are presumed to have four: mstn1a, mstn1b, mstn2a and mstn2b, a pseudogene. The mechanisms responsible for preserving these duplicates as well as the depth of mstn2b nonfunctionalization within the family remain unknown. We therefore characterized several genomic clones in order to better define species and gene phylogenies. RESULTS Gene organization and sequence conservation was particularly evident among paralog groupings and within salmonid subfamilies. All mstn2b sequences included in-frame stop codons, confirming its nonfunctionalization across taxa, although the indels and polymorphisms responsible often differed. For example, the specific indels within the Onchorhynchus tshawytscha and O. nerka genes were remarkably similar and differed equally from other mstn2b orthologs. A phylogenetic analysis weakly established a mstn2b clade including only these species, which coupled with a shared 51 base pair deletion might suggest a history involving hybridization or a shared phylogenetic history. Furthermore, mstn2 introns all lacked conserved splice site motifs, suggesting that the tissue-specific processing of mstn2a transcripts, but not those of mstn2b, is due to alternative cis regulation and is likely a common feature in salmonids. It also suggests that limited transcript processing may have contributed to mstn2b nonfunctionalization. CONCLUSIONS Previous studies revealed divergence within gene promoters while the current studies provide evidence for relaxed or positive selection in some coding sequence lineages. These results together suggest that the salmonid myostatin gene family is a novel resource for investigating mechanisms that regulate duplicate gene fate as paralog specific differences in gene expression, transcript processing and protein structure are all suggestive of active divergence.
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Affiliation(s)
- Casey B Lawson
- Department of Animal Sciences, Washington State University, Pullman, WA 99164, USA
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Li H, Sun C, Wang Y, Gao Y, Liu Y, Gao Y, Li X, Zhang C. Dynamic expression pattern of neuro-oncological ventral antigen 1 (Nova1) in the rat brain after focal cerebral ischemia/reperfusion insults. J Histochem Cytochem 2012; 61:45-54. [PMID: 23042482 DOI: 10.1369/0022155412461255] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The present study aimed to evaluate the expression of neuro-oncological ventral antigen 1 (Nova1) in cerebral ischemia/reperfusion (I/R) insults by immunohistochemistry. The focal cerebral I/R model was induced by right middle cerebral artery occlusion (MCAO) for 120 min followed by 1 day, 7 days, and 14 days of reperfusion in Sprague-Dawley (SD) rats. The results showed that Nova1 was expressed in nearly the whole brain, although with higher density in hippocampus, hypothalamus, cingulate cortex, and medial habenular nucleus. The immunoreactivity of Nova1 neurons was increased dramatically, especially on both sides of the hippocampal CA(1) region, after 1 day of reperfusion. A strong response occurred at the ipsilateral CA(1) region between 1 day and 7 days of reperfusion. Likewise, strong compensatory responses of Nova1 expression were observed on the contralateral side of the striate cortex, dentate gyrus, and hypothalamus. Interestingly, more Nova1 neurons were observed to translocate to the dendrites and growth cones of the axons in the hypothalamus on the ischemic side after 7 days of reperfusion. In conclusion, our data suggest that Nova1 might mediate neuronal responsiveness, and its expression might positively correlate with neural repair after I/R insults in the rat brain.
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Affiliation(s)
- Hualing Li
- Beijing Institute of Radiation Medicine, State Key Laboratory of Proteomics, State Key Laboratory of Medical Neurobiology, Cognitive and Mental Health Research Center, Beijing, China
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Alternative splicing: functional diversity among voltage-gated calcium channels and behavioral consequences. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1522-9. [PMID: 23022282 DOI: 10.1016/j.bbamem.2012.09.018] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/15/2012] [Accepted: 09/19/2012] [Indexed: 12/14/2022]
Abstract
Neuronal voltage-gated calcium channels generate rapid, transient intracellular calcium signals in response to membrane depolarization. Neuronal Ca(V) channels regulate a range of cellular functions and are implicated in a variety of neurological and psychiatric diseases including epilepsy, Parkinson's disease, chronic pain, schizophrenia, and bipolar disorder. Each mammalian Cacna1 gene has the potential to generate tens to thousands of Ca(V) channels by alternative pre-mRNA splicing, a process that adds fine granulation to the pool of Ca(V) channel structures and functions. The precise composition of Ca(V) channel splice isoform mRNAs expressed in each cell are controlled by cell-specific splicing factors. The activity of splicing factors are in turn regulated by molecules that encode various cellular features, including cell-type, activity, metabolic states, developmental state, and other factors. The cellular and behavioral consequences of individual sites of Ca(V) splice isoforms are being elucidated, as are the cell-specific splicing factors that control splice isoform selection. Altered patterns of alternative splicing of Ca(V) pre-mRNAs can alter behavior in subtle but measurable ways, with the potential to influence drug efficacy and disease severity. This article is part of a Special Issue entitled: Calcium channels.
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Licatalosi DD, Yano M, Fak JJ, Mele A, Grabinski SE, Zhang C, Darnell RB. Ptbp2 represses adult-specific splicing to regulate the generation of neuronal precursors in the embryonic brain. Genes Dev 2012; 26:1626-42. [PMID: 22802532 DOI: 10.1101/gad.191338.112] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing cross-linking immunoprecipitation)-generated map of reproducible Ptbp2-RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival.
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Affiliation(s)
- Donny D Licatalosi
- Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, New York 10065, USA
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Sugimoto Y, König J, Hussain S, Zupan B, Curk T, Frye M, Ule J. Analysis of CLIP and iCLIP methods for nucleotide-resolution studies of protein-RNA interactions. Genome Biol 2012; 13:R67. [PMID: 22863408 PMCID: PMC4053741 DOI: 10.1186/gb-2012-13-8-r67] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 06/11/2012] [Accepted: 08/03/2012] [Indexed: 11/12/2022] Open
Abstract
UV cross-linking and immunoprecipitation (CLIP) and individual-nucleotide resolution CLIP (iCLIP) are methods to study protein-RNA interactions in untreated cells and tissues. Here, we analyzed six published and two novel data sets to confirm that both methods identify protein-RNA cross-link sites, and to identify a slight uridine preference of UV-C-induced cross-linking. Comparing Nova CLIP and iCLIP data revealed that cDNA deletions have a preference for TTT motifs, whereas iCLIP cDNA truncations are more likely to identify clusters of YCAY motifs as the primary Nova binding sites. In conclusion, we demonstrate how each method impacts the analysis of protein-RNA binding specificity.
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Affiliation(s)
- Yoichiro Sugimoto
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Julian König
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Shobbir Hussain
- The Wellcome Trust Centre for Stem Cell Research, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Blaž Zupan
- Faculty of Computer and Information Science, University of Ljubljana, Tržaška 25, SI-1000, Ljubljana, Slovenia
| | - Tomaž Curk
- Faculty of Computer and Information Science, University of Ljubljana, Tržaška 25, SI-1000, Ljubljana, Slovenia
| | - Michaela Frye
- The Wellcome Trust Centre for Stem Cell Research, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Jernej Ule
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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Kosti I, Radivojac P, Mandel-Gutfreund Y. An integrated regulatory network reveals pervasive cross-regulation among transcription and splicing factors. PLoS Comput Biol 2012; 8:e1002603. [PMID: 22844237 PMCID: PMC3405991 DOI: 10.1371/journal.pcbi.1002603] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 05/24/2012] [Indexed: 11/19/2022] Open
Abstract
Traditionally the gene expression pathway has been regarded as being comprised of independent steps, from RNA transcription to protein translation. To date there is increasing evidence of coupling between the different processes of the pathway, specifically between transcription and splicing. To study the interplay between these processes we derived a transcription-splicing integrated network. The nodes of the network included experimentally verified human proteins belonging to three groups of regulators: transcription factors, splicing factors and kinases. The nodes were wired by instances of predicted transcriptional and alternative splicing regulation. Analysis of the network indicated a pervasive cross-regulation among the nodes; specifically, splicing factors are significantly more connected by alternative splicing regulatory edges relative to the two other subgroups, while transcription factors are more extensively controlled by transcriptional regulation. Furthermore, we found that splicing factors are the most regulated of the three regulatory groups and are subject to extensive combinatorial control by alternative splicing and transcriptional regulation. Consistent with the network results, our bioinformatics analyses showed that the subgroup of kinases have the highest density of predicted phosphorylation sites. Overall, our systematic study reveals that an organizing principle in the logic of integrated networks favor the regulation of regulatory proteins by the specific regulation they conduct. Based on these results, we propose a new regulatory paradigm postulating that gene expression regulation of the master regulators in the cell is predominantly achieved by cross-regulation.
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Affiliation(s)
- Idit Kosti
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa, Israel
| | - Predrag Radivojac
- School of Informatics and Computing, Indiana University, Bloomington, Indiana, United States of America
| | - Yael Mandel-Gutfreund
- Faculty of Biology, Technion – Israel Institute of Technology, Haifa, Israel
- * E-mail:
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Polymenidou M, Lagier-Tourenne C, Hutt KR, Bennett CF, Cleveland DW, Yeo GW. Misregulated RNA processing in amyotrophic lateral sclerosis. Brain Res 2012; 1462:3-15. [PMID: 22444279 PMCID: PMC3707312 DOI: 10.1016/j.brainres.2012.02.059] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 02/24/2012] [Accepted: 02/24/2012] [Indexed: 12/12/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) research is undergoing an era of unprecedented discoveries with the identification of new genes as major genetic causes of this disease. These discoveries reinforce the genetic, clinical and pathological overlap between ALS and frontotemporal lobar degeneration (FTLD). Common causes of these diseases include mutations in the RNA/DNA-binding proteins, TDP-43 and FUS/TLS and most recently, hexanucleotide expansions in the C9orf72 gene, discoveries that highlight the overlapping pathogenic mechanisms that trigger ALS and FTLD. TDP-43 and FUS/TLS, both of which participate in several steps of RNA processing, are abnormally aggregated and mislocalized in ALS and FTLD, while the expansion in the C9orf72 pre-mRNA strongly suggests sequestration of one or more RNA binding proteins in pathologic RNA foci. Hence, ALS and FTLD converge in pathogenic pathways disrupting the regulation of RNA processing. This article is part of a Special Issue entitled RNA-Binding Proteins.
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Affiliation(s)
- Magdalini Polymenidou
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093-6070, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
| | - Clotilde Lagier-Tourenne
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093-6070, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
| | - Kasey R. Hutt
- Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
| | - C. Frank Bennett
- Isis Pharmaceuticals, 2855 Gazelle Court, Carlsbad, CA 92010, USA
| | - Don W. Cleveland
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093-6070, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
| | - Gene W. Yeo
- Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-6070, USA
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Shang E, Cui Q, Wang X, Beseler C, Greenberg DA, Wolgemuth DJ. The bromodomain-containing gene BRD2 is regulated at transcription, splicing, and translation levels. J Cell Biochem 2012; 112:2784-93. [PMID: 21608014 DOI: 10.1002/jcb.23192] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The human BRD2 gene has been linked and associated with a form of common epilepsy and electroencephalographic abnormalities. Disruption of Brd2 in the mouse revealed that it is essential for embryonic neural development and that viable Brd2(+/-) heterozygotes show both decreased GABAergic neuron counts and increased susceptibility to seizures. To understand the molecular mechanisms by which mis-expression of BRD2 might contribute to epilepsy, we examined its regulation at multiple levels. We discovered that BRD2 expresses distinct tissue-specific transcripts that originate from different promoters and have strikingly different lengths of 5' untranslated regions (5'UTR). We also experimentally confirmed the presence of a highly conserved, alternatively spliced exon, inclusion of which would result in a premature termination of translation. Downstream of this alternative exon is a polymorphic microsatellite (GT-repeats). Manipulation of the number of the GT-repeats revealed that the length of the GT-repeats affects the ratio of the two alternative splicing products. In vitro translation and expression in cultured cells revealed that among the four different mRNAs (long and short 5'UTR combined with regular and alternative splicing), only the regularly spliced mRNA with the short 5'UTR yields full-length protein. In situ hybridization and immunohistochemical studies showed that although Brd2 mRNA is expressed in both the hippocampus and cerebellum, Brd2 protein only can be detected in the cerebellar Purkinje cells and not in hippocampal cells. These multiple levels of regulation would likely affect the production of functional BRD2 protein during neural development and hence, its role in the etiology of seizure susceptibility.
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Affiliation(s)
- Enyuan Shang
- Division of Statistical Genetics, Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York, New York 10032, USA
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Irimia M, Denuc A, Ferran JL, Pernaute B, Puelles L, Roy SW, Garcia-Fernàndez J, Marfany G. Evolutionarily conserved A-to-I editing increases protein stability of the alternative splicing factor Nova1. RNA Biol 2012; 9:12-21. [PMID: 22258141 DOI: 10.4161/rna.9.1.18387] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The structural complexity of the vertebrate brain is mirrored by its unparalleled transcriptome complexity. In particular, two post-transcriptional processes, alternative splicing and RNA editing, greatly diversify brain transcriptomes. Here we report a close connection between these two processes: we show A-to-I RNA editing in Nova1, a key brain-specific regulator of alternative splicing. Nova1 editing levels increase during embryonic development in mouse and chicken brains and show significant variation across postnatal brain regions. Evolutionary conservation of both editing and editing-associated RNA secondary structure of the Nova1 mRNA for 300 million years attests to the functional importance of Nova1 editing. Using a combination of different assays in human HEK293T cell lines, we report a novel post-translational role for this RNA editing. Whereas functional assays showed no effect of RNA editing on the regulatory splicing activity of the encoded proteins, we found evidence that edited forms exhibit reduced proteasome targeting and increased protein half-life. In addition, we found evidence for similar regulation of protein half-life by an evolutionarily conserved alternative splicing event in Nova1. These results open new venues of research on the multi-level integration of gene expression by: (1) revealing the novel role of RNA editing in regulating protein stability, and (2) establishing protein stability as a new target of multifaceted regulation.
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Affiliation(s)
- Manuel Irimia
- Departament de Genètica, Facultat de Biología, Universitat de Barcelona, Barcelona, Spain.
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Katyal S, Glubrecht DD, Li L, Gao Z, Godbout R. Disabled-1 alternative splicing in human fetal retina and neural tumors. PLoS One 2011; 6:e28579. [PMID: 22163036 PMCID: PMC3232236 DOI: 10.1371/journal.pone.0028579] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 11/10/2011] [Indexed: 11/19/2022] Open
Abstract
Background The Reelin-Dab1 signaling pathway plays a critical role in the positioning of migrating neurons, dendrite formation and lamination in the developing central nervous system. We have previously identified two alternatively spliced forms of Dab1 in the developing chick retina: an early form, Dab1-E, expressed in retinal progenitor cells, and a late form, Dab1 or Dab1-L, expressed in amacrine and ganglion cells. Compared to Dab1-L, Dab1-E lacks two exons that encode two Src family kinase (SFK) phosphorylation sites. Principal Findings Both Dab1-L and Dab1-E-like transcripts were identified in human fetal retina. Expression of human Dab1-L in primary chick retinal cultures resulted in Reelin-mediated induction of SFK phosphorylation and formation of neurite-like processes. In contrast, human Dab1-E-expressing cells retained an undifferentiated morphology. The human Dab1 gene is located within a common fragile site, and it has been postulated that it may function as a tumor suppressor. Analysis of Dab1 splice forms in retinoblastoma and neuroblastoma tumor cells revealed relative enrichment of Dab1-L-like (includes exons 7 and 8) and Dab1-E-like (excludes exons 7 and 8) transcripts in retinoblastoma and neuroblastoma, respectively. Treatment of retinoblastoma cell line RB522A with Reelin resulted in increased tyrosine phosphorylation of Dab1. As Nova2 has previously been implicated in the exclusion of exons 9B and 9C in Dab1, we examined the expression of this splicing factor in neuroblastoma and retinoblastoma cell lines. Nova2 was only detected in neuroblastoma cells, suggesting a correlation between Nova2 expression and increased levels of Dab1-E-like splice forms in neuroblastoma. Conclusions These results indicate that alternative splicing of Dab1 is conserved in avian and mammalian species, with Dab1-L driving SFK phosphorylation in both species. Dab1-E- and Dab-L-like isoforms are also expressed in childhood neural tumors, with preferential enrichment of Dab1-L-like and Dab1-E-like isoforms in retinoblastoma and neuroblastoma, respectively.
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Affiliation(s)
- Sachin Katyal
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Darryl D. Glubrecht
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Lei Li
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Zhihua Gao
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Roseline Godbout
- Department of Oncology, Cross Cancer Institute, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Protein-RNA and protein-protein recognition by dual KH1/2 domains of the neuronal splicing factor Nova-1. Structure 2011; 19:930-44. [PMID: 21742260 DOI: 10.1016/j.str.2011.05.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/29/2011] [Accepted: 05/02/2011] [Indexed: 01/05/2023]
Abstract
Nova onconeural antigens are neuron-specific RNA-binding proteins implicated in paraneoplastic opsoclonus-myoclonus-ataxia (POMA) syndrome. Nova harbors three K-homology (KH) motifs implicated in alternate splicing regulation of genes involved in inhibitory synaptic transmission. We report the crystal structure of the first two KH domains (KH1/2) of Nova-1 bound to an in vitro selected RNA hairpin, containing a UCAG-UCAC high-affinity binding site. Sequence-specific intermolecular contacts in the complex involve KH1 and the second UCAC repeat, with the RNA scaffold buttressed by interactions between repeats. Whereas the canonical RNA-binding surface of KH2 in the above complex engages in protein-protein interactions in the crystalline state, the individual KH2 domain can sequence-specifically target the UCAC RNA element in solution. The observed antiparallel alignment of KH1 and KH2 domains in the crystal structure of the complex generates a scaffold that could facilitate target pre-mRNA looping on Nova binding, thereby potentially explaining Nova's functional role in splicing regulation.
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