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Słyk Ż, Stachowiak N, Małecki M. Recombinant Adeno-Associated Virus Vectors for Gene Therapy of the Central Nervous System: Delivery Routes and Clinical Aspects. Biomedicines 2024; 12:1523. [PMID: 39062095 PMCID: PMC11274884 DOI: 10.3390/biomedicines12071523] [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: 04/19/2024] [Revised: 06/23/2024] [Accepted: 07/03/2024] [Indexed: 07/28/2024] Open
Abstract
The Central Nervous System (CNS) is vulnerable to a range of diseases, including neurodegenerative and oncological conditions, which present significant treatment challenges. The blood-brain barrier (BBB) restricts molecule penetration, complicating the achievement of therapeutic concentrations in the CNS following systemic administration. Gene therapy using recombinant adeno-associated virus (rAAV) vectors emerges as a promising strategy for treating CNS diseases, demonstrated by the registration of six gene therapy products in the past six years and 87 ongoing clinical trials. This review explores the implementation of rAAV vectors in CNS disease treatment, emphasizing AAV biology and vector engineering. Various administration methods-such as intravenous, intrathecal, and intraparenchymal routes-and experimental approaches like intranasal and intramuscular administration are evaluated, discussing their advantages and limitations in different CNS contexts. Additionally, the review underscores the importance of optimizing therapeutic efficacy through the pharmacokinetics (PK) and pharmacodynamics (PD) of rAAV vectors. A comprehensive analysis of clinical trials reveals successes and challenges, including barriers to commercialization. This review provides insights into therapeutic strategies using rAAV vectors in neurological diseases and identifies areas requiring further research, particularly in optimizing rAAV PK/PD.
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Affiliation(s)
- Żaneta Słyk
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
- Laboratory of Gene Therapy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Natalia Stachowiak
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Maciej Małecki
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
- Laboratory of Gene Therapy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
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2
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Wang C, Liu Y, Xiong J, Xie K, Wang T, Hu Y, Fu H, Zhang B, Huang X, Bao H, Cai H, Dong B, Li Z. Genome-wide CRISPR screenings identified SMCHD1 as a host-restricting factor for AAV transduction. PLoS Pathog 2024; 20:e1012344. [PMID: 38976714 PMCID: PMC11257396 DOI: 10.1371/journal.ppat.1012344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 07/18/2024] [Accepted: 06/14/2024] [Indexed: 07/10/2024] Open
Abstract
AAV-mediated gene therapy typically requires a high dose of viral transduction, risking acute immune responses and patient safety, part of which is due to limited understanding of the host-viral interactions, especially post-transduction viral genome processing. Here, through a genome-wide CRISPR screen, we identified SMCHD1 (Structural Maintenance of Chromosomes Hinge Domain 1), an epigenetic modifier, as a critical broad-spectrum restricting host factor for post-entry AAV transgene expression. SMCHD1 knock-down by RNAi and CRISPRi or knock-out by CRISPR all resulted in significantly enhanced transgene expression across multiple viral serotypes, as well as for both single-strand and self-complementary AAV genome types. Mechanistically, upon viral transduction, SMCHD1 effectively repressed AAV transcription by the formation of an LRIF1-HP1-containing protein complex and directly binding with the AAV genome to maintain a heterochromatin-like state. SMCHD1-KO or LRIF1-KD could disrupt such a complex and thus result in AAV transcriptional activation. Together, our results highlight the host factor-induced chromatin remodeling as a critical inhibitory mechanism for AAV transduction and may shed light on further improvement in AAV-based gene therapy.
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Affiliation(s)
- Chenlu Wang
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Yu Liu
- National Clinical Research Center for Geriatrics and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Jingfei Xiong
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Kun Xie
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Tianshu Wang
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Yu Hu
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Huancheng Fu
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Baiquan Zhang
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Xiaochao Huang
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Hui Bao
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Haoyang Cai
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
| | - Biao Dong
- National Clinical Research Center for Geriatrics and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
- Sichuan Real and Best Biotech Co., Ltd., Chengdu, China
| | - Zhonghan Li
- Center of Growth Metabolism and Aging, State Key Laboratory of Oral Disease, West China Hospital of Stomatology, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu, China
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3
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Ling C, Yu C, Wang C, Yang M, Yang H, Yang K, He Y, Shen Y, Tang S, Yu X, Zhou Z, Zhou S, Zhou J, Zhu L, Li J. rAAV capsid mutants eliminate leaky expression from DNA donor template for homologous recombination. Nucleic Acids Res 2024; 52:6518-6531. [PMID: 38783157 PMCID: PMC11194064 DOI: 10.1093/nar/gkae401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 04/28/2024] [Accepted: 05/04/2024] [Indexed: 05/25/2024] Open
Abstract
Precise genomic editing through the combination of CRISPR/Cas systems and recombinant adeno-associated virus (rAAV)-delivered homology directed repair (HDR) donor templates represents a powerful approach. However, the challenge of effectively suppressing leaky transcription from the rAAV vector, a phenomenon associated to cytotoxicity, persists. In this study, we demonstrated substantial promoter activities of various homology arms and inverted terminal repeats (ITR). To address this issue, we identified a novel rAAV variant, Y704T, which not only yields high-vector quantities but also effectively suppresses in cis mRNA transcription driven by a robust promoter. The Y704T variant maintains normal functionality in receptor interaction, intracellular trafficking, nuclear entry, uncoating, and second-strand synthesis, while specifically exhibiting defects in transcription. Importantly, this inhibitory effect is found to be independent of ITR, promoter types, and RNA polymerases. Mechanistic studies unveiled the involvement of Valosin Containing Protein (VCP/p97) in capsid-mediated transcription repression. Remarkably, the Y704T variant delivers HDR donor templates without compromising DNA replication ability and homologous recombination efficiency. In summary, our findings enhance the understanding of capsid-regulated transcription and introduce novel avenues for the application of the rAAV-CRISPR/Cas9 system in human gene therapy.
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Affiliation(s)
- Chen Ling
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
| | - Chenghui Yu
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Cong Wang
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Ming Yang
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Hengbin Yang
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Keying Yang
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Yun He
- State Key Laboratory of Genetic Engineering and Engineering Research Center of Gene Technology (Ministry of Education), School of Life Sciences, Zhongshan Hospital, Fudan University, Shanghai 200438, China
| | - Yajie Shen
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Huashan Hospital, Shanghai Engineering Research Center of Industrial Microorganisms, MOE Engineering Research Center of Gene Technology, Fudan University, Shanghai 200438, China
| | - Shiyi Tang
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
| | - Xiaomin Yu
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
| | - Zhengjun Zhou
- Department of Liver Surgery and Transplantation, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Shaolai Zhou
- Department of Liver Surgery and Transplantation, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Jian Zhou
- Department of Liver Surgery and Transplantation, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Liqing Zhu
- Department of Clinical Laboratory, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China
- Department of Clinical Laboratory, Peking University Cancer Hospital and Institute, Beijing 100142, China
| | - Jixi Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Huashan Hospital, Shanghai Engineering Research Center of Industrial Microorganisms, MOE Engineering Research Center of Gene Technology, Fudan University, Shanghai 200438, China
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4
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Pohorilets I, Beard JP, Driscoll JL, Schmitz JC, Koide K. Synthesis and antiproliferative activity of a tetrahydrofuran analog of FR901464. Bioorg Med Chem Lett 2024; 104:129739. [PMID: 38599298 DOI: 10.1016/j.bmcl.2024.129739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/03/2024] [Accepted: 04/06/2024] [Indexed: 04/12/2024]
Abstract
FR901464 is a natural product that exhibits antiproliferative activity at single-digit nanomolar concentrations in cancer cells. Its tetrahydropyran-spiroepoxide covalently binds the spliceosome. Through our medicinal chemistry campaign, we serendipitously discovered that a bromoetherification formed a tetrahydrofuran. The tetrahydrofuran analog was three orders of magnitude less potent than the corresponding tetrahydropyran analogs. This study shows the significance of the tetrahydropyran ring that presents the epoxide toward the spliceosome.
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Affiliation(s)
- Ivanna Pohorilets
- Department of Chemistry, University of Pittsburgh 219 Parkman Avenue, Pittsburgh, PA 15260, United States
| | - Jacob P Beard
- Department of Chemistry, University of Pittsburgh 219 Parkman Avenue, Pittsburgh, PA 15260, United States
| | - Julia L Driscoll
- Department of Chemistry, University of Pittsburgh 219 Parkman Avenue, Pittsburgh, PA 15260, United States
| | - John C Schmitz
- Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh School of Medicine 5150 Centre Avenue, Pittsburgh, PA 15232, United States; Cancer Therapeutics Program, UPMC Hillman Cancer Center 5117 Centre Ave, Pittsburgh, PA 15232, United States
| | - Kazunori Koide
- Department of Chemistry, University of Pittsburgh 219 Parkman Avenue, Pittsburgh, PA 15260, United States; Cancer Therapeutics Program, UPMC Hillman Cancer Center 5117 Centre Ave, Pittsburgh, PA 15232, United States.
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5
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Pierce GF, Fong S, Long BR, Kaczmarek R. Deciphering conundrums of adeno-associated virus liver-directed gene therapy: focus on hemophilia. J Thromb Haemost 2024; 22:1263-1289. [PMID: 38103734 DOI: 10.1016/j.jtha.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 11/07/2023] [Accepted: 12/01/2023] [Indexed: 12/19/2023]
Abstract
Adeno-associated virus gene therapy has been the subject of intensive investigation for monogenic disease gene addition therapy for more than 25 years, yet few therapies have been approved by regulatory agencies. Most have not progressed beyond phase 1/2 due to toxicity, lack of efficacy, or both. The liver is a natural target for adeno-associated virus since most serotypes have a high degree of tropism for hepatocytes due to cell surface receptors for the virus and the unique liver sinusoidal geometry facilitating high volumes of blood contact with hepatocyte cell surfaces. Recessive monogenic diseases such as hemophilia represent promising targets since the defective proteins are often synthesized in the liver and secreted into the circulation, making them easy to measure, and many do not require precise regulation. Yet, despite initiation of many disease-specific clinical trials, therapeutic windows are often nonexistent, resulting in excess toxicity and insufficient efficacy. Iterative progress built on these attempts is best illustrated by hemophilia, with the first regulatory approvals for factor IX and factor VIII gene therapies eventually achieved 25 years after the first gene therapy studies in humans. Although successful gene transfer may result in the production of sufficient transgenic protein to modify the disease, many emerging questions on durability, predictability, reliability, and variability of response have not been answered. The underlying biology accounting for these heterogeneous responses and the interplay between host and virus is the subject of intense investigation and the subject of this review.
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Affiliation(s)
- Glenn F Pierce
- World Federation of Hemophilia, Montreal, Quebec, Canada.
| | - Sylvia Fong
- BioMarin Pharmaceutical Inc, Research and Early Development, Novato, California, USA
| | - Brian R Long
- BioMarin Pharmaceutical Inc, Research and Early Development, Novato, California, USA
| | - Radoslaw Kaczmarek
- Department of Pediatrics, Indiana University School of Medicine, Wells Center for Pediatric Research, Indiana, USA; Laboratory of Glycobiology, Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw, Poland
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6
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Loeb EJ, Havlik PL, Elmore ZC, Rosales A, Fergione SM, Gonzalez TJ, Smith TJ, Benkert AR, Fiflis DN, Asokan A. Capsid-mediated control of adeno-associated viral transcription determines host range. Cell Rep 2024; 43:113902. [PMID: 38431840 PMCID: PMC11150003 DOI: 10.1016/j.celrep.2024.113902] [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: 09/19/2023] [Revised: 01/13/2024] [Accepted: 02/16/2024] [Indexed: 03/05/2024] Open
Abstract
Adeno-associated virus (AAV) is a member of the genus Dependoparvovirus, which infects a wide range of vertebrate species. Here, we observe that, unlike most primate AAV isolates, avian AAV is transcriptionally silenced in human cells. By swapping the VP1 N terminus from primate AAVs (e.g., AAV8) onto non-mammalian isolates (e.g., avian AAV), we identify a minimal component of the AAV capsid that controls viral transcription and unlocks robust transduction in both human cells and mouse tissue. This effect is accompanied by increased AAV genome chromatin accessibility and altered histone methylation. Proximity ligation analysis reveals that host factors are selectively recruited by the VP1 N terminus of AAV8 but not avian AAV. Notably, these include AAV essential factors implicated in the nuclear factor κB pathway, chromatin condensation, and histone methylation. We postulate that the AAV capsid has evolved mechanisms to recruit host factors to its genome, allowing transcriptional activation in a species-specific manner.
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Affiliation(s)
- Ezra J Loeb
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Patrick L Havlik
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Zachary C Elmore
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Alan Rosales
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Sophia M Fergione
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA
| | - Trevor J Gonzalez
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA
| | - Timothy J Smith
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA
| | - Abigail R Benkert
- Department of Surgery, Duke University School of Medicine, Durham, NC, USA
| | - David N Fiflis
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Aravind Asokan
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, USA; Department of Surgery, Duke University School of Medicine, Durham, NC, USA.
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7
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Kraszewska I, Sarad K, Andrysiak K, Kopacz A, Schmidt L, Krüger M, Dulak J, Jaźwa-Kusior A. Casein kinase 2 activity is a host restriction factor for AAV transduction. Mol Ther 2024; 32:84-102. [PMID: 37952087 PMCID: PMC10787142 DOI: 10.1016/j.ymthe.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 09/29/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
So far, the mechanisms that impede AAV transduction, especially in the human heart, are poorly understood, hampering the introduction of new, effective gene therapy strategies. Therefore, the aim of this study was to identify and overcome the main cellular barriers to successful transduction in the heart, using induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs), iPSC-derived cardiac fibroblasts (iPSC-CFs), and primary endothelial cells to model vector-host interactions. Through phosphoproteome analysis we established that casein kinase 2 (CK2) signaling is one of the most significantly affected pathways upon AAV exposure. Transient inhibition of CK2 activity substantially enhanced the transduction rate of AAV2, AAV6, and AAV9 in all tested cell types. In particular, CK2 inhibition improved the trafficking of AAVs through the cytoplasm, impaired DNA damage response through destabilization of MRE11, and altered the RNA processing pathways, which were also highly responsive to AAV transduction. Also, it augmented transgene expression in already transduced iPSC-CFs, which retain AAV genomes in a functional, but probably silent form. In summary, the present study provides new insights into the current understanding of the host-AAV vector interaction, identifying CK2 activity as a key barrier to efficient transduction and transgene expression, which may translate to improving the outcome of AAV-based therapies in the future.
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Affiliation(s)
- Izabela Kraszewska
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
| | - Katarzyna Sarad
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland; Doctoral School of Exact and Natural Sciences, Jagiellonian University, Krakow, Poland
| | - Kalina Andrysiak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Aleksandra Kopacz
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Luisa Schmidt
- CECAD Research Center, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Marcus Krüger
- CECAD Research Center, Institute for Genetics, University of Cologne, Cologne, Germany
| | - Józef Dulak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Agnieszka Jaźwa-Kusior
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
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8
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Gonzalez-Sandoval A, Pekrun K, Tsuji S, Zhang F, Hung KL, Chang HY, Kay MA. The AAV capsid can influence the epigenetic marking of rAAV delivered episomal genomes in a species dependent manner. Nat Commun 2023; 14:2448. [PMID: 37117181 PMCID: PMC10147666 DOI: 10.1038/s41467-023-38106-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 04/17/2023] [Indexed: 04/30/2023] Open
Abstract
Recombinant adeno-associated viral vectors (rAAVs) are among the most commonly used vehicles for in vivo based gene therapies. However, it is hard to predict which AAV capsid will provide the most robust expression in human subjects due to the observed discordance in vector-mediated transduction between species. In our study, we use a primate specific capsid, AAV-LK03, to demonstrate that the limitation of this capsid towards transduction of mouse cells is unrelated to cell entry and nuclear transport but rather due to depleted histone H3 chemical modifications related to active transcription, namely H3K4me3 and H3K27ac, on the vector DNA itself. A single-amino acid insertion into the AAV-LK03 capsid enables efficient transduction and the accumulation of active-related epigenetic marks on the vector chromatin in mouse without compromising transduction efficiency in human cells. Our study suggests that the capsid protein itself is involved in driving the epigenetic status of the vector genome, most likely during the process of uncoating. Programming viral chromatin states by capsid design may enable facile DNA transduction between vector and host species and ultimately lead to rational selection of AAV capsids for use in humans.
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Affiliation(s)
- Adriana Gonzalez-Sandoval
- Department of Pediatrics, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
- Encoded Therapeutics, South San Francisco, CA, USA
| | - Katja Pekrun
- Department of Pediatrics, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - Shinnosuke Tsuji
- Department of Pediatrics, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
- Specialty Medicine Research Laboratories I, Daiichi Sankyo Co., Ltd., Tokyo, Japan
| | - Feijie Zhang
- Department of Pediatrics, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
| | - King L Hung
- Department of Dermatology, Stanford University, Stanford, CA, USA
| | - Howard Y Chang
- Department of Dermatology, Stanford University, Stanford, CA, USA
- Center for Personal Dynamic Regulomes and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Mark A Kay
- Department of Pediatrics, Stanford University, Stanford, CA, USA.
- Department of Genetics, Stanford University, Stanford, CA, USA.
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9
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Host Cell Restriction Factors Blocking Efficient Vector Transduction: Challenges in Lentiviral and Adeno-Associated Vector Based Gene Therapies. Cells 2023; 12:cells12050732. [PMID: 36899868 PMCID: PMC10001033 DOI: 10.3390/cells12050732] [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: 12/15/2022] [Revised: 02/02/2023] [Accepted: 02/08/2023] [Indexed: 03/03/2023] Open
Abstract
Gene therapy relies on the delivery of genetic material to the patient's cells in order to provide a therapeutic treatment. Two of the currently most used and efficient delivery systems are the lentiviral (LV) and adeno-associated virus (AAV) vectors. Gene therapy vectors must successfully attach, enter uncoated, and escape host restriction factors (RFs), before reaching the nucleus and effectively deliver the therapeutic genetic instructions to the cell. Some of these RFs are ubiquitously expressed in mammalian cells, while others are cell-specific, and others still are expressed only upon induction by danger signals as type I interferons. Cell restriction factors have evolved to protect the organism against infectious diseases and tissue damage. These restriction factors can be intrinsic, directly acting on the vector, or related with the innate immune response system, acting indirectly through the induction of interferons, but both are intertwined. The innate immunity is the first line of defense against pathogens and, as such cells derived from myeloid progenitors (but not only), are well equipped with RFs to detect pathogen-associated molecular patterns (PAMPs). In addition, some non-professional cells, such as epithelial cells, endothelial cells, and fibroblasts, play major roles in pathogen recognition. Unsurprisingly, foreign DNA and RNA molecules are among the most detected PAMPs. Here, we review and discuss identified RFs that block LV and AAV vector transduction, hindering their therapeutic efficacy.
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10
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Chen T, Yang H, Liu P, Hamiti M, Zhang X, Xu Y, Quan W, Zhang Y, Yu W, Jiao L, Du T, Xi J, Yin B, Zhou W, Lu S, Peng X. Splicing factor SF3B3, a NS5-binding protein, restricts ZIKV infection by targeting GCH1. Virol Sin 2022; 38:222-232. [PMID: 36572150 PMCID: PMC10176263 DOI: 10.1016/j.virs.2022.12.005] [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: 08/16/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Zika virus (ZIKV), a positive-sense single-stranded RNA virus, causes congenital ZIKV syndrome in children and Guillain-Barré Syndrome (GBS) in adults. ZIKV expresses nonstructural protein 5 (NS5), a large protein that is essential for viral replication. ZIKV NS5 confers the ability to evade interferon (IFN) signalling; however, the exact mechanism remains unclear. In this study, we employed affinity pull-down and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses and found that splicing factor 3b subunit 3 (SF3B3) is associated with the NS5-Flag pull-down complex through interaction with NS5. Functional assays showed that SF3B3 overexpression inhibited ZIKV replication by promoting IFN-stimulated gene (ISG) expression whereas silencing of SF3B3 inhibited expression of ISGs to promote ZIKV replication. GTP cyclohydrolase I (GCH1) is the first and rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis. NS5 upregulates the expression of GCH1 during ZIKV infection. And GCH1 marginally promoted ZIKV replication via the IFN pathway. Additionally, GCH1 expression is related to the regulation of SF3B3. Overexpression of the SF3B3 protein effectively reduced GCH1 protein levels, whereas SF3B3 knockdown increased its levels. These findings indicated that ZIKV NS5 binding protein SF3B3 contributed to the host immune response against ZIKV replication by modulating the expression of GCH1.
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Affiliation(s)
- Tanxiu Chen
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China; Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital, Nanchang, 330029, China
| | - Hao Yang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Penghui Liu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Moliduer Hamiti
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Xintian Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Yi Xu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Wenqi Quan
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Yong Zhang
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Wenhai Yu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Li Jiao
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Tingfu Du
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Juemin Xi
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China
| | - Bin Yin
- The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Wei Zhou
- Department of Science and Education, Jiangxi Key Laboratory of Translational Cancer Research, Jiangxi Cancer Hospital, Nanchang, 330029, China
| | - Shuaiyao Lu
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China.
| | - Xiaozhong Peng
- Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Kunming, 650031, China; The State Key Laboratory of Medical Molecular Biology, Department of Molecular Biology and Biochemistry, Institute of Basic Medical Sciences, Medical Primate Research Center, Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
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11
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Meyer NL, Chapman MS. Adeno-associated virus (AAV) cell entry: structural insights. Trends Microbiol 2022; 30:432-451. [PMID: 34711462 PMCID: PMC11225776 DOI: 10.1016/j.tim.2021.09.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 09/02/2021] [Accepted: 09/14/2021] [Indexed: 02/07/2023]
Abstract
Adeno-associated virus (AAV) is the leading vector in emerging treatments of inherited diseases. Higher transduction efficiencies and cellular specificity are required for broader clinical application, motivating investigations of virus-host molecular interactions during cell entry. High-throughput methods are identifying host proteins more comprehensively, with subsequent molecular studies revealing unanticipated complexity and serotype specificity. Cryogenic electron microscopy (cryo-EM) provides a path towards structural details of these sometimes heterogeneous virus-host complexes, and is poised to illuminate more fully the steps in entry. Here presented, is progress in understanding the distinct steps of glycan attachment, and receptor-mediated entry/trafficking. Comparison with structures of antibody complexes provides new insights on immune neutralization with implications for the design of improved gene therapy vectors.
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Affiliation(s)
- Nancy L Meyer
- Pacific Northwest Cryo-EM Center, Oregon Health and Science University (OHSU) Center for Spatial Systems Biomedicine, Portland, OR, USA
| | - Michael S Chapman
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
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12
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Fludarabine increases nuclease-free AAV- and CRISPR/Cas9-mediated homologous recombination in mice. Nat Biotechnol 2022; 40:1285-1294. [PMID: 35393561 DOI: 10.1038/s41587-022-01240-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/28/2022] [Indexed: 12/12/2022]
Abstract
Homologous recombination (HR)-based gene therapy using adeno-associated viruses (AAV-HR) without nucleases has several advantages over classic gene therapy, especially the potential for permanent transgene expression. However, the low efficiency of AAV-HR remains a major limitation. Here, we tested a series of small-molecule compounds and found that ribonucleotide reductase (RNR) inhibitors substantially enhance AAV-HR efficiency in mouse and human liver cell lines approximately threefold. Short-term administration of the RNR inhibitor fludarabine increased the in vivo efficiency of both non-nuclease- and CRISPR/Cas9-mediated AAV-HR two- to sevenfold in the murine liver, without causing overt toxicity. Fludarabine administration induced transient DNA damage signaling in both proliferating and quiescent hepatocytes. Notably, the majority of AAV-HR events occurred in non-proliferating hepatocytes in both fludarabine-treated and control mice, suggesting that the induction of transient DNA repair signaling in non-dividing hepatocytes was responsible for enhancing AAV-HR efficiency in mice. These results suggest that use of a clinically approved RNR inhibitor can potentiate AAV-HR-based genome-editing therapeutics.
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13
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Riyad JM, Weber T. Intracellular trafficking of adeno-associated virus (AAV) vectors: challenges and future directions. Gene Ther 2021; 28:683-696. [PMID: 33658649 PMCID: PMC8413391 DOI: 10.1038/s41434-021-00243-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/27/2021] [Accepted: 02/05/2021] [Indexed: 02/07/2023]
Abstract
In the last two decades, recombinant adeno-associated virus has emerged as the most popular gene therapy vector. Recently AAV gene therapy has been approved by the FDA for the treatment of two rare genetic disorders, namely the early childhood blindness disease Leber congenital amaurosis and spinal muscular atrophy (SMA). As is the case for the treatment of SMA, if the AAV vector must be administered systemically, very high vector doses are often required for therapeutic efficacy. But higher vector doses inevitably increase the risk of adverse events. The tragic death of three children in a clinical trial to treat X-linked myotubular myopathy with an AAV vector has thrown this limitation into sharp relief. Regardless of the precise cause(s) that led to the death of the two children, it is critical that we develop better AAV vectors to achieve therapeutic levels of expression with lower vector doses. To transduce successfully a target cell, AAV has to overcome both systemic as well as cellular roadblocks. In this review, we discuss some of the most prominent cellular roadblocks that AAV must get past to deliver successfully its therapeutic payload. We also highlight recent advancements in our knowledge of AAV biology that can potentially be harnessed to improve AAV vector performance and thereby make AAV gene therapy safer.
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Affiliation(s)
- Jalish M Riyad
- Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Thomas Weber
- Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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14
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Wang H, Chan TW, Vashisht AA, Drew BG, Calkin AC, Harris TE, Wohlschlegel JA, Xiao X, Reue K. Lipin 1 modulates mRNA splicing during fasting adaptation in liver. JCI Insight 2021; 6:e150114. [PMID: 34494556 PMCID: PMC8492312 DOI: 10.1172/jci.insight.150114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/23/2021] [Indexed: 01/03/2023] Open
Abstract
Lipin 1 regulates cellular lipid homeostasis through roles in glycerolipid synthesis (through phosphatidic acid phosphatase activity) and transcriptional coactivation. Lipin 1-deficient individuals exhibit episodic disease symptoms that are triggered by metabolic stress, such as stress caused by prolonged fasting. We sought to identify critical lipin 1 activities during fasting. We determined that lipin 1 deficiency induces widespread alternative mRNA splicing in liver during fasting, much of which is normalized by refeeding. The role of lipin 1 in mRNA splicing was largely independent of its enzymatic function. We identified interactions between lipin 1 and spliceosome proteins, as well as a requirement for lipin 1 to maintain homeostatic levels of spliceosome small nuclear RNAs and specific RNA splicing factors. In fasted Lpin1-/- liver, we identified a correspondence between alternative splicing of phospholipid biosynthetic enzymes and dysregulated phospholipid levels; splicing patterns and phospholipid levels were partly normalized by feeding. Thus, lipin 1 influences hepatic lipid metabolism through mRNA splicing, as well as through enzymatic and transcriptional activities, and fasting exacerbates the deleterious effects of lipin 1 deficiency on metabolic homeostasis.
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Affiliation(s)
- Huan Wang
- Human Genetics, David Geffen School of Medicine at UCLA
| | | | - Ajay A Vashisht
- Biological Chemistry, University of California, Los Angeles, California, USA
| | - Brian G Drew
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Anna C Calkin
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia.,Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Baker Department of Cardiometabolic Health, University of Melbourne, Parkville, Victoria, Australia
| | - Thurl E Harris
- Pharmacology, University of Virginia, Charlottesville, Virginia, USA
| | - James A Wohlschlegel
- Biological Chemistry, University of California, Los Angeles, California, USA.,Molecular Biology Institute and
| | - Xinshu Xiao
- Bioinformatics Interdepartmental Program and.,Molecular Biology Institute and.,Integrative Biology and Physiology, University of California, Los Angeles, California, USA
| | - Karen Reue
- Human Genetics, David Geffen School of Medicine at UCLA,,Molecular Biology Institute and
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15
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Bohlen MO, McCown TJ, Powell SK, El-Nahal HG, Daw T, Basso MA, Sommer MA, Samulski RJ. Adeno-Associated Virus Capsid-Promoter Interactions in the Brain Translate from Rat to the Nonhuman Primate. Hum Gene Ther 2020; 31:1155-1168. [PMID: 32940068 DOI: 10.1089/hum.2020.196] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recently, we established an adeno-associated virus (AAV9) capsid-promoter interaction that directly determined cell-specific gene expression across two synthetic promoters, Cbh and CBA, in the rat striatum. These studies not only expand this capsid-promoter interaction to include another promoter in the rat striatum but also establish AAV capsid-promoter interactions in the nonhuman primate brain. When AAV serotype 9 (AAV9) vectors were injected into the rat striatum, the minimal synthetic promoter JetI drove green fluorescent protein (GFP) gene expression predominantly in oligodendrocytes. However, similar to our previous findings, the insertion of six alanines into VP1/VP2 of the AAV9 capsid (AAV9AU) significantly shifted JetI-driven GFP gene expression to neurons. In addition, previous retrograde tracing studies in the nonhuman primate brain also revealed the existence of a capsid-promoter interaction. When rAAV2-Retro vectors were infused into the frontal eye field (FEF) of rhesus macaques, local gene expression was prominent using either the hybrid chicken beta actin (CAG) or human synapsin (hSyn) promoters. However, only the CAG promoter, not the hSyn promoter, led to gene expression in the ipsilateral claustrum and contralateral FEF. Conversely, infusion of rAAV2-retro-hSyn vectors, but not rAAV2-retro-CAG, into the macaque superior colliculus led to differential and selective retrograde gene expression in cerebellotectal afferent cells. Clearly, this differential promoter/capsid expression profile could not be attributed to promoter inactivation from retrograde transport of the rAAV2-Retro vector. In summary, we document the potential for AAV capsid/promoter interactions to impact cell-specific gene expression across species, experimental manipulations, and engineered capsids, independent of capsid permissivity.
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Affiliation(s)
- Martin O Bohlen
- Department Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Thomas J McCown
- Departments of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Departments of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,UNC Gene Therapy Center, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA
| | - Sara K Powell
- UNC Gene Therapy Center, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA.,Asklepios Biopharmaceutical, Inc., Research Triangle Park, NC, USA
| | - Hala G El-Nahal
- Department Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Tierney Daw
- Department Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Michele A Basso
- Fuster Laboratory of Cognitive Neuroscience, Department of Psychiatry and Biobehavioral Sciences and Neurobiology, and Jane and Terry Semel Institute for Neuroscience and Human Behavior, Brain Research Institute-David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Marc A Sommer
- Department Biomedical Engineering, Duke University, Durham, North Carolina, USA.,Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, USA.,Center for Cognitive Neuroscience, Duke University, Durham, North Carolina, USA
| | - R Jude Samulski
- UNC Gene Therapy Center, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA.,Departments of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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16
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Journey to the Center of the Cell: Tracing the Path of AAV Transduction. Trends Mol Med 2020; 27:172-184. [PMID: 33071047 DOI: 10.1016/j.molmed.2020.09.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/13/2020] [Accepted: 09/15/2020] [Indexed: 02/08/2023]
Abstract
As adeno-associated virus (AAV)-based gene therapies are being increasingly approved for use in humans, it is important that we understand vector-host interactions in detail. With the advances in genome-wide genetic screening tools, a clear picture of AAV-host interactions is beginning to emerge. Understanding these interactions can provide insights into the viral life cycle. Accordingly, novel strategies to circumvent the current limitations of AAV-based vectors may be explored. Here, we summarize our current understanding of the various stages in the journey of the vector from the cell surface to the nucleus and contextualize the roles of recently identified host factors.
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17
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Breaking the sound barrier: Towards next-generation AAV vectors for gene therapy of hearing disorders. Hear Res 2020; 413:108092. [PMID: 33268240 DOI: 10.1016/j.heares.2020.108092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 09/14/2020] [Accepted: 10/08/2020] [Indexed: 12/20/2022]
Abstract
Owing to the advances in transgenic animal technology and the advent of the next-generation sequencing era, over 120 genes causing hereditary hearing loss have been identified by now. In parallel, the field of human gene therapy continues to make exciting and rapid progress, culminating in the recent approval of several ex vivo and in vivo applications. Despite these encouraging developments and the growing interest in causative treatments for hearing disorders, gene therapeutic interventions in the inner ear remain in their infancy and await clinical translation. This review focuses on the adeno-associated virus (AAV), which nowadays represents one of the safest and most promising vectors in gene therapy. We first provide an overview of AAV biology and outline the principles of therapeutic gene transfer with recombinant AAV vectors, before pointing out major challenges and solutions for clinical translation including vector manufacturing and species translatability. Finally, we highlight seminal technologies for engineering and selection of next-generation "designer" AAV capsids, and illustrate their power and potential with recent examples of their application for inner ear gene transfer in animals.
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18
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SUMOylation Targets Adeno-associated Virus Capsids but Mainly Restricts Transduction by Cellular Mechanisms. J Virol 2020; 94:JVI.00871-20. [PMID: 32669341 DOI: 10.1128/jvi.00871-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 07/08/2020] [Indexed: 11/20/2022] Open
Abstract
Adeno-associated virus (AAV) has proven to be a promising candidate for gene therapy due to its nonpathogenic nature, ease of production, and broad tissue tropism. However, its transduction capabilities are not optimal due to the interaction with various host factors within the cell. In a previous study, we identified members of the small ubiquitin-like modifier (SUMO) pathway as significant restriction factors in AAV gene transduction. In the present study, we explored the scope of this restriction by focusing on the AAV capsid and host cell proteins as targets. We show that during vector production, the capsid protein VP2 becomes SUMOylated, as indicated by deletion and point mutations of VP2 or the obstruction of its N terminus via the addition of a tag. We observed that SUMOylated AAV capsids display higher stability than non-SUMOylated capsids. Prevention of capsid SUMOylation by VP2 mutations did not abolish transduction restriction by SUMOylation; however, it reduced activation of gene transduction by shutdown of the cellular SUMOylation pathway. This indicates a link between capsid SUMOylation and SUMOylation of cellular proteins in restricting gene transduction. Infection with AAV triggers general SUMOylation of cellular proteins. In particular, the DAXX protein, a putative host cell restriction factor that can become SUMOylated, is able to restrict AAV gene transduction by reducing the intracellular accumulation of AAV vectors. We also observe that the coexpression of a SUMOylation inhibitor with an AAV2 reporter gene vector increased gene transduction significantly.IMPORTANCE Host factors within the cell are the major mode of restriction of adeno-associated virus (AAV) and keep it from fulfilling its maximum potential as a gene therapy vector. A better understanding of the intricacies of restriction would enable the engineering of better vectors. Via a genome-wide short interfering RNA screen, we identified that proteins of the small ubiquitin-like modifier (SUMO) pathway play an important role in AAV restriction. In this study, we investigate whether this restriction is targeted to the AAV directly or indirectly through host cell factors. The results indicate that both targets act in concert to restrict AAV.
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19
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Maurer AC, Weitzman MD. Adeno-Associated Virus Genome Interactions Important for Vector Production and Transduction. Hum Gene Ther 2020; 31:499-511. [PMID: 32303138 PMCID: PMC7232694 DOI: 10.1089/hum.2020.069] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 04/16/2020] [Indexed: 12/12/2022] Open
Abstract
Recombinant adeno-associated virus has emerged as one of the most promising gene therapy delivery vectors. Development of these vectors took advantage of key features of the wild-type adeno-associated virus (AAV), enabled by basic studies of the underlying biology and requirements for transcription, replication, and packaging of the viral genome. Each step in generating and utilizing viral vectors involves numerous molecular interactions that together determine the efficiency of vector production and gene delivery. Once delivered into the cell, interactions with host proteins will determine the fate of the viral genome, and these will impact the intended goal of gene delivery. Here, we provide an overview of known interactions of the AAV genome with viral and cellular proteins involved in its amplification, packaging, and expression. Further appreciation of how the AAV genome interacts with host factors will enhance how this simple virus can be harnessed for an array of vector purposes that benefit human health.
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Affiliation(s)
- Anna C. Maurer
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
| | - Matthew D. Weitzman
- Division of Protective Immunity, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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20
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Sun C. The SF3b complex: splicing and beyond. Cell Mol Life Sci 2020; 77:3583-3595. [PMID: 32140746 PMCID: PMC7452928 DOI: 10.1007/s00018-020-03493-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/13/2020] [Accepted: 02/20/2020] [Indexed: 12/17/2022]
Abstract
The SF3b complex is an intrinsic component of the functional U2 small nuclear ribonucleoprotein (snRNP). As U2 snRNP enters nuclear pre-mRNA splicing, SF3b plays key roles in recognizing the branch point sequence (BPS) and facilitating spliceosome assembly and activation. Since the discovery of SF3b, substantial progress has been made in elucidating its molecular mechanism during splicing. In addition, numerous recent studies indicate that SF3b and its components are engaged in various molecular and cellular events that are beyond the canonical role in splicing. This review summarizes the current knowledge on the SF3b complex and highlights its multiple roles in splicing and beyond.
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Affiliation(s)
- Chengfu Sun
- Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, 610500, China.
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21
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A CRISPR Screen Identifies the Cell Polarity Determinant Crumbs 3 as an Adeno-associated Virus Restriction Factor in Hepatocytes. J Virol 2019; 93:JVI.00943-19. [PMID: 31391273 DOI: 10.1128/jvi.00943-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/06/2019] [Indexed: 12/21/2022] Open
Abstract
Adeno-associated viruses (AAV) are helper-dependent parvoviruses that have been developed into promising gene therapy vectors. Many studies, including a recent unbiased genomic screen, have identified host factors essential for AAV cell entry, but no genome-wide screens that address inhibitory host factors have been reported. Here, we utilize a novel CRISPR screen to identify AAV restriction factors in a human hepatocyte cell line. The major hit from our gain-of-function screen is the apical polarity determinant Crumbs 3 (Crb3). Knockout (KO) of Crb3 enhances AAV transduction, while overexpression exerts the opposite effect. Further, Crb3 appears to restrict AAV transduction in a serotype- and cell type-specific manner. Particularly, for AAV serotype 9 and a rationally engineered AAV variant, we demonstrate that increased availability of galactosylated glycans on the surfaces of Crb3 KO cells, but not the universal AAV receptor, leads to increased capsid attachment and enhanced transduction. We postulate that Crb3 could serve as a key molecular determinant that restricts the availability of AAV glycan attachment factors on the cell surface by maintaining apical-basal polarity and tight junction integrity.IMPORTANCE Adeno-associated viruses (AAVs) have recently emerged at the forefront as gene therapy vectors; however, our understanding of host factors that influence AAV transduction in different cell types is still evolving. In the present study, we perform a genome-scale CRISPR knockout screen to identify cellular host factors that restrict AAV infection in hepatocyte cultures. We discover that Crumbs 3, which determines cellular polarity, also influences the distribution of certain carbohydrate attachment factors on the cell surface. This in turn affects the ability of virions to bind and enter the cells. This study underscores the importance of cell polarity in AAV transduction and provides a potential molecular basis for the differential infectious mechanism(s) in cell culture versus organ systems.
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22
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Madigan VJ, Yuziuk JA, Chiarella AM, Tyson TO, Meganck RM, Elmore ZC, Tse LV, Hathaway NA, Asokan A. Ring finger protein 121 is a potent regulator of adeno-associated viral genome transcription. PLoS Pathog 2019; 15:e1007988. [PMID: 31386698 PMCID: PMC6697353 DOI: 10.1371/journal.ppat.1007988] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 08/16/2019] [Accepted: 07/17/2019] [Indexed: 12/12/2022] Open
Abstract
Adeno-associated viruses (AAV) are Dependoparvoviruses that have shown promise as recombinant vectors for gene therapy. While infectious pathways of AAV are well studied, gaps remain in our understanding of host factors affecting vector genome expression. Here, we map the role of ring finger protein 121 (RNF121), an E3 ubiquitin ligase, as a key regulator of AAV genome transcription. CRISPR-mediated knockout of RNF121 (RNF121 KO) in different cells markedly decreased AAV transduction regardless of capsid serotype or vector dose. Recombinant AAV transduction is partially rescued by overexpressing RNF121, but not by co-infection with helper Adenovirus. Major steps in the AAV infectious pathway including cell surface binding, cellular uptake, nuclear entry, capsid uncoating and second strand synthesis are unaffected. While gene expression from transfected plasmids or AAV genomes is unaffected, mRNA synthesis from AAV capsid-associated genomes is markedly decreased in RNF121 KO cells. These observations were attributed to transcriptional arrest as corroborated by RNAPol-ChIP and mRNA half-life measurements. Although AAV capsid proteins do not appear to be direct substrates of RNF121, the catalytic domain of the E3 ligase appears essential. Inhibition of ubiquitin-proteasome pathways revealed that blocking Valosin Containing Protein (VCP/p97), which targets substrates to the proteasome, can selectively and completely restore AAV-mediated transgene expression in RNF121 KO cells. Expanding on this finding, transcriptomic and proteomic analysis revealed that the catalytic subunit of DNA PK (DNAPK-Cs), a known activator of VCP, is upregulated in RNF121 KO cells and that the DNA damage machinery is enriched at sites of stalled AAV genome transcription. We postulate that a network of RNF121, VCP and DNA damage response elements function together to regulate transcriptional silencing and/or activation of AAV vector genomes. Recombinant AAV vectors are at the forefront of clinical gene therapy. There is a need to better understand the mechanisms dictating AAV transduction in the host. Here, we identify a network of host proteins involving RNF121, p97 and the DNA damage machinery as potent factors regulating AAV genome transcription. Our study sheds light on an understudied aspect of AAV biology with implications for gene therapy.
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Affiliation(s)
- Victoria J. Madigan
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Gene Therapy Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Surgery, Duke University School of Medicine, Durham, NC, United States of America
| | - Julianne A. Yuziuk
- Gene Therapy Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Anna M. Chiarella
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, Chapel Hill, NC, United States of America
| | - Tyne O. Tyson
- Department of Surgery, Duke University School of Medicine, Durham, NC, United States of America
| | - Rita M. Meganck
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Gene Therapy Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Surgery, Duke University School of Medicine, Durham, NC, United States of America
| | - Zachary C. Elmore
- Department of Surgery, Duke University School of Medicine, Durham, NC, United States of America
- Department of Molecular Genetics & Microbiology, Duke University School of Medicine, Durham, NC, United States of America
| | - Longping V. Tse
- Gene Therapy Center, the University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Nathaniel A. Hathaway
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, Chapel Hill, NC, United States of America
| | - Aravind Asokan
- Department of Surgery, Duke University School of Medicine, Durham, NC, United States of America
- Department of Molecular Genetics & Microbiology, Duke University School of Medicine, Durham, NC, United States of America
- * E-mail:
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23
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Komatsu Y, Takeuchi D, Tokunaga T, Sakurai H, Makino A, Honda T, Ikeda Y, Tomonaga K. RNA Virus-Based Episomal Vector with a Fail-Safe Switch Facilitating Efficient Genetic Modification and Differentiation of iPSCs. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2019; 14:47-55. [PMID: 31309127 PMCID: PMC6606997 DOI: 10.1016/j.omtm.2019.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 05/15/2019] [Indexed: 12/24/2022]
Abstract
A gene delivery system that allows efficient and safe stem cell modification is critical for next-generation stem cell therapies. An RNA virus-based episomal vector (REVec) is a gene transfer system developed based on Borna disease virus (BoDV), which facilitates persistent intranuclear RNA transgene delivery without integrating into the host genome. In this study, we analyzed susceptibility of human induced pluripotent stem cell (iPSC) lines from different somatic cell sources to REVec, along with commonly used viral vectors, and demonstrated highly efficient REVec transduction of iPSCs. Using REVec encoding myogenic transcription factor MyoD1, we further demonstrated potential application of the REVec system for inducing differentiation of iPSCs into skeletal muscle cells. Of note, treatment with a small molecule, T-705, completely eliminated REVec in persistently transduced cells. Thus, the REVec system offers a versatile toolbox for stable, integration-free iPSC modification and trans-differentiation, with a unique switch-off mechanism.
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Affiliation(s)
- Yumiko Komatsu
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.,The Keihanshin Consortium for Fostering the Next Generation of Global Leaders in Research (K-CONNEX), Kyoto University, Kyoto 606-8501, Japan
| | - Dan Takeuchi
- Section of Bacterial Drug Resistance Research, Thailand-Japan Research Collaboration Center, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Tomoya Tokunaga
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan
| | - Hidetoshi Sakurai
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto 606-8507, Japan
| | - Akiko Makino
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.,Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto 606-8507, Japan
| | - Tomoyuki Honda
- Division of Virology, Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
| | - Yasuhiro Ikeda
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Keizo Tomonaga
- Laboratory of RNA Viruses, Department of Virus Research, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.,Department of Mammalian Regulatory Network, Graduate School of Biostudies, Kyoto University, Kyoto 606-8507, Japan.,Department of Molecular Virology, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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24
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Lu B, Kurmi K, Munoz-Gomez M, Jacobus Ambuludi EJ, Tonne JM, Rakshit K, Hitosugi T, Kudva YC, Matveyenko AV, Ikeda Y. Impaired β-cell glucokinase as an underlying mechanism in diet-induced diabetes. Dis Model Mech 2018; 11:dmm033316. [PMID: 29915142 PMCID: PMC6031355 DOI: 10.1242/dmm.033316] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/26/2018] [Indexed: 12/22/2022] Open
Abstract
High-fat diet (HFD)-fed mouse models have been widely used to study early type 2 diabetes. Decreased β-cell glucokinase (GCK) expression has been observed in HFD-induced diabetes. However, owing to its crucial roles in glucose metabolism in the liver and in islet β-cells, the contribution of decreased GCK expression to the development of HFD-induced diabetes is unclear. Here, we employed a β-cell-targeted gene transfer vector and determined the impact of β-cell-specific increase in GCK expression on β-cell function and glucose handling in vitro and in vivo Overexpression of GCK enhanced glycolytic flux, ATP-sensitive potassium channel activation and membrane depolarization, and increased proliferation in Min6 cells. β-cell-targeted GCK transduction did not change glucose handling in chow-fed C57BL/6 mice. Although adult mice fed a HFD showed reduced islet GCK expression, impaired glucose tolerance and decreased glucose-stimulated insulin secretion (GSIS), β-cell-targeted GCK transduction improved glucose tolerance and restored GSIS. Islet perifusion experiments verified restored GSIS in isolated HFD islets by GCK transduction. Thus, our data identify impaired β-cell GCK expression as an underlying mechanism for dysregulated β-cell function and glycemic control in HFD-induced diabetes. Our data also imply an etiological role of GCK in diet-induced diabetes.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Brian Lu
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA
- Virology and Gene Therapy Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA
| | - Kiran Kurmi
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA
- Molecular Pharmacology and Experimental Therapeutics Graduate Program, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN 55905, USA
| | | | | | - Jason M Tonne
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Kuntol Rakshit
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Taro Hitosugi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905, USA
| | - Yogish C Kudva
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN 55905, USA
| | - Aleksey V Matveyenko
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA
| | - Yasuhiro Ikeda
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55905, USA
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25
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Herrmann AK, Grimm D. High-Throughput Dissection of AAV-Host Interactions: The Fast and the Curious. J Mol Biol 2018; 430:2626-2640. [PMID: 29782834 DOI: 10.1016/j.jmb.2018.05.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 12/24/2022]
Abstract
Over 50 years after its initial description, adeno-associated virus (AAV) remains the most exciting but also most elusive study object in basic or applied virology. On the one hand, its simple structure not only facilitates investigations into virus biology but, combined with the availability of numerous natural AAV variants with distinct infection efficiency and specificity, also makes AAV a preferred substrate for engineering of gene delivery vectors. On the other hand, it is striking to witness a recent flurry of reports that highlight and partially close persistent gaps in our understanding of AAV virus and vector biology. This is all the more perplexing considering that recombinant AAVs have already been used in >160 clinical trials and recently been commercialized as gene therapeutics. Here, we discuss a reason for these advances in AAV research, namely, the advent and application of powerful high-throughput technology for dissection of AAV-host interactions and optimization of AAV gene therapy vectors. As relevant examples, we focus on the discovery of (i) a "new" cellular AAV receptor, AAVR, (ii) host restriction factors for AAV entry, and (iii) AAV capsid determinants that mediate trafficking through the blood-brain barrier. While items i/ii are prototypes of extra- or intracellular AAV host factors that were identified via high-throughput screenings, item iii exemplifies the power of molecular evolution to investigate the virus itself. In the future, we anticipate that these and other key technologies will continue to accelerate the dissection of AAV biology and will yield a wealth of new designer viruses for clinical use.
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Affiliation(s)
- Anne-Kathrin Herrmann
- Cluster of Excellence CellNetworks,Virus-Host Interaction Group, Department of Infectious Diseases/Virology, Heidelberg University Hospital, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; BioQuant Center, University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Dirk Grimm
- Cluster of Excellence CellNetworks,Virus-Host Interaction Group, Department of Infectious Diseases/Virology, Heidelberg University Hospital, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; BioQuant Center, University of Heidelberg, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany; German Center for Infection Research (DZIF), Partner site Heidelberg, 69120 Heidelberg, Germany.
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26
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Morsy SG, Tonne JM, Zhu Y, Lu B, Budzik K, Krempski JW, Ali SA, El-Feky MA, Ikeda Y. Divergent susceptibilities to AAV-SaCas9-gRNA vector-mediated genome-editing in a single-cell-derived cell population. BMC Res Notes 2017; 10:720. [PMID: 29221488 PMCID: PMC5721606 DOI: 10.1186/s13104-017-3028-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/29/2017] [Indexed: 01/05/2023] Open
Abstract
OBJECTIVE Recombinant adeno-associated virus (AAV)-based vectors are characterized by their robust and safe transgene delivery. The CRISPR/Cas9 and guide RNA (gRNA) system present a promising genome-editing platform, and a recent development of a shorter Cas9 enzyme from Staphylococcus aureus (SaCas9) allows generation of high titer single AAV vectors which carry both saCas9- and gRNA-expression cassettes. Here, we used two AAV-SaCas9 vectors with distinct GFP-targeted gRNA sequences and determined the impact of AAV-SaCas9-gRNA vector treatment in a single cell clone carrying a GFP-expression cassette. RESULTS Our results showed comparable GFP knockout efficiencies (40-50%) upon a single low-dose infection. Three consecutive transductions of 25-fold higher doses of vectors showed 80% GFP knockout efficiency. To analyze the "AAV-SaCas9-resistant cell population", we sorted the residual GFP-positive cells and assessed their permissiveness to super-infection with two AAV-Cas9-GFP vectors. We found the sorted cells were significantly more resistant to the GFP knockout mediated by the same AAV vector, but not by the other GFP-targeted AAV vector. Our data therefore demonstrate highly efficient genome-editing by the AAV-SaCas9-gRNA vector system. Differential susceptibilities of single cell-derived cells to the AAV-SaCas9-gRNA-mediated genome editing may represent a formidable barrier to achieve 100% genome editing efficiency by this vector system.
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Affiliation(s)
- Salma G. Morsy
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
- Cancer Biology, South Egypt Cancer Institute, Assiut University, Assiut, Egypt
| | - Jason M. Tonne
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
| | - Yaxi Zhu
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
| | - Brian Lu
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
| | - Karol Budzik
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
| | - James W. Krempski
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
| | - Sherine A. Ali
- Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Mohamed A. El-Feky
- Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Yasuhiro Ikeda
- Department of Molecular Medicine, Mayo Clinic, College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
- Center for Regenerative Medicine, Mayo Clinic, College of Medicine, Rochester, MN 55905 USA
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27
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Site Specific Modification of Adeno-Associated Virus Enables Both Fluorescent Imaging of Viral Particles and Characterization of the Capsid Interactome. Sci Rep 2017; 7:14766. [PMID: 29116194 PMCID: PMC5676692 DOI: 10.1038/s41598-017-15255-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 10/24/2017] [Indexed: 01/10/2023] Open
Abstract
Adeno-associated viruses (AAVs) are attractive gene therapy vectors due to their low toxicity, high stability, and rare integration into the host genome. Expressing ligands on the viral capsid can re-target AAVs to new cell types, but limited sites have been identified on the capsid that tolerate a peptide insertion. Here, we incorporated a site-specific tetracysteine sequence into the AAV serotype 9 (AAV9) capsid, to permit labelling of viral particles with either a fluorescent dye or biotin. We demonstrate that fluorescently labelled particles are detectable in vitro, and explore the utility of the method in vivo in mice with time-lapse imaging. We exploit the biotinylated viral particles to generate two distinct AAV interactomes, and identify several functional classes of proteins that are highly represented: actin/cytoskeletal protein binding, RNA binding, RNA splicing/processing, chromatin modifying, intracellular trafficking and RNA transport proteins. To examine the biological relevance of the capsid interactome, we modulated the expression of two proteins from the interactomes prior to AAV transduction. Blocking integrin αVβ6 receptor function reduced AAV9 transduction, while reducing histone deacetylase 4 (HDAC4) expression enhanced AAV transduction. Our method demonstrates a strategy for inserting motifs into the AAV capsid without compromising viral titer or infectivity.
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28
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Grimm D, Büning H. Small But Increasingly Mighty: Latest Advances in AAV Vector Research, Design, and Evolution. Hum Gene Ther 2017; 28:1075-1086. [DOI: 10.1089/hum.2017.172] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Dirk Grimm
- Heidelberg University Hospital, Cluster of Excellence CellNetworks, Department of Infectious Diseases, Virology, Heidelberg, Germany
- BioQuant Center, University of Heidelberg, Heidelberg, Germany
- German Center for Infection Research (DZIF), partner site Heidelberg, Germany
| | - Hildegard Büning
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany
- Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, Germany
- German Center for Infection Research (DZIF), partner site Hannover-Braunschweig, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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29
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Muik A, Reul J, Friedel T, Muth A, Hartmann KP, Schneider IC, Münch RC, Buchholz CJ. Covalent coupling of high-affinity ligands to the surface of viral vector particles by protein trans-splicing mediates cell type-specific gene transfer. Biomaterials 2017; 144:84-94. [PMID: 28825979 DOI: 10.1016/j.biomaterials.2017.07.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/18/2017] [Accepted: 07/22/2017] [Indexed: 02/04/2023]
Abstract
We have established a novel approach for the covalent coupling of large polypeptides to the surface of fully assembled adeno-associated viral gene transfer vector (AAV) particles via split-intein mediated protein-trans-splicing (PTS). This way, we achieved selective gene transfer to distinct cell types. Single-chain variable fragments (scFvs) or designed ankyrin repeat proteins (DARPins), exhibiting high-affinity binding to cell surface receptors selectively expressed on the surface of target cells, were coupled to AAV particles harboring mutations in the capsid proteins which ablate natural receptor usage. Both, the AAV capsid protein VP2 and multiple separately produced targeting ligands recognizing Her2/neu, EpCAM, CD133 or CD30 were genetically fused with complementary split-intein domains. Optimized coupling conditions led to an effective conjugation of each targeting ligand to the universal AAV capsid and translated into specific gene transfer into target receptor-positive cell types in vitro and in vivo. Interestingly, PTS-based AAVs exhibited significantly less gene transfer into target receptor-negative cells than AAVs displaying the same targeting ligand but coupled genetically. Another important consequence of the PTS technology is the possibility to now display scFvs or other antibody-derived domain formats harboring disulfide-bonds in a functionally active form on the surface of AAV particles. Hence, the custom combination of a universal AAV vector particle and targeting ligands of various formats allows for an unprecedented flexibility in the generation of gene transfer vectors targeted to distinct cell types.
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Affiliation(s)
- Alexander Muik
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Johanna Reul
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Thorsten Friedel
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Anke Muth
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | | | - Irene C Schneider
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Robert C Münch
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Christian J Buchholz
- Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, 63225, Langen, Germany.
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30
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Pillay S, Carette JE. Host determinants of adeno-associated viral vector entry. Curr Opin Virol 2017; 24:124-131. [PMID: 28672171 DOI: 10.1016/j.coviro.2017.06.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 05/28/2017] [Accepted: 06/09/2017] [Indexed: 12/18/2022]
Abstract
Viral vectors based on adeno-associated virus (AAV) are leading candidates for therapeutic gene delivery. Understanding rate-limiting steps in the entry of AAV vectors may be used in a rational approach to improve efficiency and specificity of transduction. This review describes our current understanding of AAV entry, a key step during infection. We discuss the identity and functions of AAV receptors and attachment factors, including the recently discovered multi-serotype receptor AAVR. We further provide an overview of other host factors that act during the trafficking stage of AAV vector transduction. In particular, we focus on cellular protein complexes associated with retrograde transport from endosomes to the trans-Golgi network. The novel insights in AAV-host interactions facilitated by technological advances in genetic screening approaches provide a greater depth in our understanding how AAV vectors exploit host factors to deliver its genetic cargo to the nucleus.
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Affiliation(s)
- Sirika Pillay
- Stanford University, Department of Microbiology and Immunology, Stanford, CA 94305, USA
| | - Jan E Carette
- Stanford University, Department of Microbiology and Immunology, Stanford, CA 94305, USA.
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31
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Pham D, Koide K. Discoveries, target identifications, and biological applications of natural products that inhibit splicing factor 3B subunit 1. Nat Prod Rep 2017; 33:637-47. [PMID: 26812544 DOI: 10.1039/c5np00110b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Covering: 1992 to 2015The natural products FR901464, pladienolide, and herboxidiene were discovered as activators of reporter gene systems. Unexpectedly, these compounds target neither transcription nor translation; rather, they target splicing factor 3B subunit 1 of the spliceosome, causing changes in splicing patterns. All of them showed anticancer activity in a low nanomolar range. Since their discovery, these molecules have been used in a variety of biological applications.
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Affiliation(s)
- Dianne Pham
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA.
| | - Kazunori Koide
- Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA.
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32
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Cellular transduction mechanisms of adeno-associated viral vectors. Curr Opin Virol 2016; 21:54-60. [PMID: 27544821 DOI: 10.1016/j.coviro.2016.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 07/30/2016] [Accepted: 08/01/2016] [Indexed: 12/27/2022]
Abstract
Recombinant adeno-associated viral vectors (rAAV) are regarded as promising vehicles for therapeutic gene delivery. Continued development and new strategies are essential to improve the potency of AAV vectors and reduce the effective dose needed for clinical efficacy. In this regard, many studies have focused on understanding the cellular transduction mechanisms of rAAV, often with the goal of exploiting this knowledge to increase gene transfer efficiency. Here, we provide an overview of our evolving understanding of rAAV cellular trafficking pathways through the host cell, beginning with cellular entry and ending with transcription of the vector genome. Strategies to exploit this information for improving rAAV transduction are discussed.
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33
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De Maio FA, Risso G, Iglesias NG, Shah P, Pozzi B, Gebhard LG, Mammi P, Mancini E, Yanovsky MJ, Andino R, Krogan N, Srebrow A, Gamarnik AV. The Dengue Virus NS5 Protein Intrudes in the Cellular Spliceosome and Modulates Splicing. PLoS Pathog 2016; 12:e1005841. [PMID: 27575636 PMCID: PMC5004807 DOI: 10.1371/journal.ppat.1005841] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 08/03/2016] [Indexed: 11/22/2022] Open
Abstract
Dengue virus NS5 protein plays multiple functions in the cytoplasm of infected cells, enabling viral RNA replication and counteracting host antiviral responses. Here, we demonstrate a novel function of NS5 in the nucleus where it interferes with cellular splicing. Using global proteomic analysis of infected cells together with functional studies, we found that NS5 binds spliceosome complexes and modulates endogenous splicing as well as minigene-derived alternative splicing patterns. In particular, we show that NS5 alone, or in the context of viral infection, interacts with core components of the U5 snRNP particle, CD2BP2 and DDX23, alters the inclusion/exclusion ratio of alternative splicing events, and changes mRNA isoform abundance of known antiviral factors. Interestingly, a genome wide transcriptome analysis, using recently developed bioinformatics tools, revealed an increase of intron retention upon dengue virus infection, and viral replication was improved by silencing specific U5 components. Different mechanistic studies indicate that binding of NS5 to the spliceosome reduces the efficiency of pre-mRNA processing, independently of NS5 enzymatic activities. We propose that NS5 binding to U5 snRNP proteins hijacks the splicing machinery resulting in a less restrictive environment for viral replication.
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Affiliation(s)
| | - Guillermo Risso
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA-CONICET), Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
| | | | - Priya Shah
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
| | - Berta Pozzi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA-CONICET), Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
| | | | - Pablo Mammi
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA-CONICET), Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
| | | | | | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, United States of America
| | - Nevan Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
| | - Anabella Srebrow
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE, UBA-CONICET), Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
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34
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Mutants at the 2-Fold Interface of Adeno-associated Virus Type 2 (AAV2) Structural Proteins Suggest a Role in Viral Transcription for AAV Capsids. J Virol 2016; 90:7196-7204. [PMID: 27252527 PMCID: PMC4984656 DOI: 10.1128/jvi.00493-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/19/2016] [Indexed: 01/21/2023] Open
Abstract
We previously reported that an amino acid substitution, Y704A, near the 2-fold interface of adeno-associated virus (AAV) was defective for transcription of the packaged genome (M. Salganik, F. Aydemir, H. J. Nam, R. McKenna, M. Agbandje-McKenna, and N. Muzyczka, J Virol 88:1071–1079, 2013, doi: http://dx.doi.org/10.1128/JVI.02093-13). In this report, we have characterized the defect in 6 additional capsid mutants located in a region ∼30 Å in diameter on the surface of the AAV type 2 (AAV2) capsid near the 2-fold interface. These mutants, which are highly conserved among primate serotypes, displayed a severe defect (3 to 6 logs) in infectivity. All of the mutants accumulated significant levels of uncoated DNA in the nucleus, but none of the mutants were able to accumulate significant amounts of genomic mRNA postinfection. In addition, wild-type (wt) capsids that were bound to the conformational antibody A20, which is known to bind the capsid surface in the region of the mutants, were also defective for transcription. In all cases, the mutant virus particles, as well as the antibody-bound wild-type capsids, were able to enter the cell, travel to the nucleus, uncoat, and synthesize a second strand but were unable to transcribe their genomes. Taken together, the phenotype of these mutants provides compelling evidence that the AAV capsid plays a role in the transcription of its genome, and the mutants map this functional region on the surface of the capsid near the 2-fold interface. This appears to be the first example of a viral structural protein that is also involved in the transcription of the viral genome that it delivers to the nucleus. IMPORTANCE Many viruses package enzymes within their capsids that assist in expressing their genomes postinfection, e.g., retroviruses. A number of nonenveloped viruses, including AAV, carry proteases that are needed for capsid maturation or for capsid modification during infection. We describe here what appears to be the first example of a nonenveloped viral capsid that appears to have a role in promoting transcription. A total of six mutants at the AAV capsid 2-fold interface were shown to have a severe defect in expressing their genomes, and the defect was at the level of mRNA accumulation. This suggests that AAV capsids have a novel role in promoting the transcription of the genomes that they have packaged. Since wt virions could not complement the mutant viruses, and the mutant viruses did not effectively inhibit wt gene expression, our results suggest that the capsid exerts its effect on transcription in cis.
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35
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De La Garza A, Cameron RC, Nik S, Payne SG, Bowman TV. Spliceosomal component Sf3b1 is essential for hematopoietic differentiation in zebrafish. Exp Hematol 2016; 44:826-837.e4. [PMID: 27260753 DOI: 10.1016/j.exphem.2016.05.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 10/21/2022]
Abstract
SF3B1 (Splicing factor 3b, subunit 1) is one of the most commonly mutated factors in myelodysplastic syndrome (MDS). Although the genetic correlation between SF3B1 mutations and MDS etiology are quite strong, no in vivo model currently exists to explore how SF3B1 loss alters blood cell development. Using zebrafish mutants, we show here that proper function of Sf3b1 is required for all hematopoietic lineages. As in MDS patients, zebrafish sf3b1 mutants develop a macrocytic-anemia-like phenotype due to a block in maturation at a late progenitor stage. The mutant embryos also develop neutropenia, because their primitive myeloid cells fail to mature and turn on differentiation markers such as l-plastin and myeloperoxidase. In contrast, production of definitive hematopoietic stem and progenitor cells (HSPCs) from hemogenic endothelial cells within the dorsal aorta is greatly diminished, whereas arterial endothelial cells are correctly fated. Notch signaling, imperative for the endothelial-to-hematopoietic transition, is also normal, indicating that HSPC induction is blocked in sf3b1 mutants downstream or independent of Notch signaling. The data demonstrate that Sf3b1 function is necessary during key differentiation fate decisions in multiple blood cell types. Zebrafish sf3b1 mutants offer a novel animal model with which to explore the role of splicing in hematopoietic development and provide an excellent in vivo system with which to delve into the question of why and how Sf3b1 dysfunction is detrimental to hematopoietic differentiation, which could improve MDS diagnosis and treatment.
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Affiliation(s)
- Adriana De La Garza
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Rosannah C Cameron
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Sara Nik
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Sara G Payne
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Teresa V Bowman
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Gottesman Institute for Stem Cell Biology and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Medicine (Oncology), Albert Einstein College of Medicine, Bronx, NY, USA.
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Dhar S, La Clair JJ, León B, Hammons JC, Yu Z, Kashyap MK, Castro JE, Burkart MD. A Carbohydrate-Derived Splice Modulator. J Am Chem Soc 2016; 138:5063-8. [PMID: 27058259 DOI: 10.1021/jacs.5b13427] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Small-molecule splice modulators have recently been recognized for their clinical potential for diverse cancers. This, combined with their use as tools to study the importance of splice-regulated events and their association with disease, continues to fuel the discovery of new splice modulators. One of the key challenges found in the current class of materials arises from their instability, where rapid metabolic degradation can lead to off-target responses. We now describe the preparation of bench-stable splice modulators by adapting carbohydrate motifs as a central scaffold to provide rapid access to potent splice modulators.
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Affiliation(s)
- Sachin Dhar
- Department of Chemistry and Biochemistry, University of California-San Diego , 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - James J La Clair
- Department of Chemistry and Biochemistry, University of California-San Diego , 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Brian León
- Department of Chemistry and Biochemistry, University of California-San Diego , 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Justin C Hammons
- Department of Chemistry and Biochemistry, University of California-San Diego , 9500 Gilman Drive, La Jolla, California 92093-0358, United States
| | - Zhe Yu
- Moores Cancer Center, University of California-San Diego , La Jolla, California 92093-0358, United States
| | - Manoj K Kashyap
- Moores Cancer Center, University of California-San Diego , La Jolla, California 92093-0358, United States
| | - Januario E Castro
- Moores Cancer Center, University of California-San Diego , La Jolla, California 92093-0358, United States
| | - Michael D Burkart
- Department of Chemistry and Biochemistry, University of California-San Diego , 9500 Gilman Drive, La Jolla, California 92093-0358, United States
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Functional Genomic Strategies for Elucidating Human-Virus Interactions: Will CRISPR Knockout RNAi and Haploid Cells? Adv Virus Res 2016; 94:1-51. [PMID: 26997589 PMCID: PMC7112329 DOI: 10.1016/bs.aivir.2015.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Over the last several years a wealth of transformative human–virus interaction discoveries have been produced using loss-of-function functional genomics. These insights have greatly expanded our understanding of how human pathogenic viruses exploit our cells to replicate. Two technologies have been at the forefront of this genetic revolution, RNA interference (RNAi) and random retroviral insertional mutagenesis using haploid cell lines (haploid cell screening), with the former technology largely predominating. Now the cutting edge gene editing of the CRISPR/Cas9 system has also been harnessed for large-scale functional genomics and is poised to possibly displace these earlier methods. Here we compare and contrast these three screening approaches for elucidating host–virus interactions, outline their key strengths and weaknesses including a comparison of an arrayed multiple orthologous RNAi reagent screen to a pooled CRISPR/Cas9 human rhinovirus 14–human cell interaction screen, and recount some notable insights made possible by each. We conclude with a brief perspective on what might lie ahead for the fast evolving field of human–virus functional genomics.
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