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Marmion RA, Simpkins AG, Barrett LA, Denberg DW, Zusman S, Schottenfeld-Roames J, Schüpbach T, Shvartsman SY. Stochastic phenotypes in RAS-dependent developmental diseases. Curr Biol 2023; 33:807-816.e4. [PMID: 36706752 PMCID: PMC10026697 DOI: 10.1016/j.cub.2023.01.008] [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: 06/08/2022] [Revised: 12/02/2022] [Accepted: 01/05/2023] [Indexed: 01/27/2023]
Abstract
Germline mutations upregulating RAS signaling are associated with multiple developmental disorders. A hallmark of these conditions is that the same mutation may present vastly different phenotypes in different individuals, even in monozygotic twins. Here, we demonstrate how the origins of such largely unexplained phenotypic variations may be dissected using highly controlled studies in Drosophila that have been gene edited to carry activating variants of MEK, a core enzyme in the RAS pathway. This allowed us to measure the small but consistent increase in signaling output of such alleles in vivo. The fraction of mutation carriers reaching adulthood was strongly reduced, but most surviving animals had normal RAS-dependent structures. We rationalize these results using a stochastic signaling model and support it by quantifying cell fate specification errors in bilaterally symmetric larval trachea, a RAS-dependent structure that allows us to isolate the effects of mutations from potential contributions of genetic modifiers and environmental differences. We propose that the small increase in signaling output shifts the distribution of phenotypes into a regime, where stochastic variation causes defects in some individuals, but not in others. Our findings shed light on phenotypic heterogeneity of developmental disorders caused by deregulated RAS signaling and offer a framework for investigating causal effects of other pathogenic alleles and mild mutations in general.
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Affiliation(s)
- Robert A Marmion
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
| | - Alison G Simpkins
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
| | - Lena A Barrett
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
| | - David W Denberg
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
| | - Susan Zusman
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
| | | | - Trudi Schüpbach
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Stanislav Y Shvartsman
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Flatiron Institute, Simons Foundation, New York, NY 10010, USA.
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Fraire-Zamora JJ, Tosi S, Solon J, Casanova J. Control of hormone-driven organ disassembly by ECM remodeling and Yorkie-dependent apoptosis. Curr Biol 2021; 31:5261-5273.e4. [PMID: 34666006 DOI: 10.1016/j.cub.2021.09.057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 06/30/2021] [Accepted: 09/22/2021] [Indexed: 01/13/2023]
Abstract
Epithelia grow and shape into functional structures during organogenesis. Although most of the focus on organogenesis has been drawn to the building of biological structures, the disassembly of pre-existing structures is also an important event to reach a functional adult organ. Examples of disassembly processes include the regression of the Müllerian or Wolffian ducts during gonad development and mammary gland involution during the post-lactational period in adult females. To date, it is unclear how organ disassembly is controlled at the cellular level. Here, we follow the Drosophila larval trachea through metamorphosis and show that its disassembly is a hormone-driven and precisely orchestrated process. It occurs in two phases: first, remodeling of the apical extracellular matrix (aECM), mediated by matrix metalloproteases and independent of the actomyosin cytoskeleton, results in a progressive shortening of the entire trachea and a nuclear-to-cytoplasmic relocalization of the Hippo effector Yorkie (Yki). Second, a decreased transcription of the Yki target, Diap1, in the posterior metameres and the activation of caspases result in the apoptotic loss of the posterior half of the trachea while the anterior half escapes cell death. Thus, our work unravels a mechanism by which hormone-driven ECM remodeling controls sequential tissue shortening and apoptotic cell removal through the transcriptional activity of Yki, leading to organ disassembly during animal development.
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Affiliation(s)
- Juan J Fraire-Zamora
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Institut de Biologia Molecular de Barcelona (CSIC), Barcelona, Catalonia, Spain; Institut de Recerca Biomèdica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain; Instituto Biofisika (CSIC, UPV/EHU), Basque Excellence Research Centre, Barrio Sarriena, 48940 Leioa, Spain.
| | - Sébastien Tosi
- Institut de Recerca Biomèdica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain
| | - Jérôme Solon
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Universitat Pompeu Fabra (UPF), Barcelona 08003, Spain; Instituto Biofisika (CSIC, UPV/EHU), Basque Excellence Research Centre, Barrio Sarriena, 48940 Leioa, Spain; Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain.
| | - Jordi Casanova
- Institut de Biologia Molecular de Barcelona (CSIC), Barcelona, Catalonia, Spain; Institut de Recerca Biomèdica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10, 08028 Barcelona, Spain
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Zhu JY, Lee JG, van de Leemput J, Lee H, Han Z. Functional analysis of SARS-CoV-2 proteins in Drosophila identifies Orf6-induced pathogenic effects with Selinexor as an effective treatment. Cell Biosci 2021; 11:59. [PMID: 33766136 PMCID: PMC7992514 DOI: 10.1186/s13578-021-00567-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/02/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND SARS-CoV-2 causes COVID-19 with a widely diverse disease profile that affects many different tissues. The mechanisms underlying its pathogenicity in host organisms remain unclear. Animal models for studying the pathogenicity of SARS-CoV-2 proteins are lacking. METHODS Using bioinformatic analysis, we found that 90% of the virus-host interactions involve human proteins conserved in Drosophila. Therefore, we generated a series of transgenic fly lines for individual SARS-CoV-2 genes, and used the Gal4-UAS system to express these viral genes in Drosophila to study their pathogenicity. RESULTS We found that the ubiquitous expression of Orf6, Nsp6 or Orf7a in Drosophila led to reduced viability and tissue defects, including reduced trachea branching as well as muscle deficits resulting in a "held-up" wing phenotype and poor climbing ability. Furthermore, muscles in these flies showed dramatically reduced mitochondria. Since Orf6 was found to interact with nucleopore proteins XPO1, we tested Selinexor, a drug that inhibits XPO1, and found that it could attenuate the Orf6-induced lethality and tissue-specific phenotypes observed in flies. CONCLUSIONS Our study established Drosophila as a model for studying the function of SARS-CoV2 genes, identified Orf6 as a highly pathogenic protein in various tissues, and demonstrated the potential of Selinexor for inhibiting Orf6 toxicity using an in vivo animal model system.
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Affiliation(s)
- Jun-Yi Zhu
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jin-Gu Lee
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hangnoh Lee
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
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