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Catlin JP, Schaner Tooley CE. Exploring potential developmental origins of common neurodegenerative disorders. Biochem Soc Trans 2024; 52:1035-1044. [PMID: 38661189 DOI: 10.1042/bst20230422] [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: 09/11/2023] [Revised: 03/12/2024] [Accepted: 04/11/2024] [Indexed: 04/26/2024]
Abstract
In the United States, it is now estimated that 6.7 million people over the age of 65 are afflicted by Alzheimer's disease (AD), over 1 million people are living with Parkinson's disease (PD), and over 200 000 have or are at risk for developing Huntington's disease (HD). All three of these neurodegenerative diseases result in the ultimate death of distinct neuronal subtypes, and it is widely thought that age-related damage is the single biggest contributing factor to this neuronal death. However, recent studies are now suggesting that developmental defects during early neurogenesis could also play a role in the pathology of neurodegenerative diseases. Loss or overexpression of proteins associated with HD, PD, and AD also result in embryonic phenotypes but whether these developmental defects slowly unmask over time and contribute to age-related neurodegeneration remains highly debated. Here, we discuss known links between embryonic neurogenesis and neurodegenerative disorders (including common signaling pathways), potential compensatory mechanisms that could delay presentation of neurodegenerative disorders, and the types of model systems that could be used to study these links in vivo.
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Affiliation(s)
- James P Catlin
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, U.S.A
| | - Christine E Schaner Tooley
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, U.S.A
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Rossant J. Why study human embryo development? Dev Biol 2024; 509:43-50. [PMID: 38325560 DOI: 10.1016/j.ydbio.2024.02.001] [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: 08/21/2023] [Revised: 12/31/2023] [Accepted: 02/01/2024] [Indexed: 02/09/2024]
Abstract
Understanding the processes and mechanisms underlying early human embryo development has become an increasingly active and important area of research. It has potential for insights into important clinical issues such as early pregnancy loss, origins of congenital anomalies and developmental origins of adult disease, as well as fundamental insights into human biology. Improved culture systems for preimplantation embryos, combined with the new tools of single cell genomics and live imaging, are providing new insights into the similarities and differences between human and mouse development. However, access to human embryo material is still restricted and extended culture of early embryos has regulatory and ethical concerns. Stem cell-derived models of different phases of human development can potentially overcome these limitations and provide a scalable source of material to explore the early postimplantation stages of human development. To date, such models are clearly incomplete replicas of normal development but future technological improvements can be envisaged. The ethical and regulatory environment for such studies remains to be fully resolved.
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Affiliation(s)
- Janet Rossant
- The Gairdner Foundation and the Hospital for Sick Children, University of Toronto, MaRS Centre, Heritage Building, 101 College Street, Suite 335, Toronto, Ontario, M5G 1L7, Canada.
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Thompson LM, Orr HT. HD and SCA1: Tales from two 30-year journeys since gene discovery. Neuron 2023; 111:3517-3530. [PMID: 37863037 PMCID: PMC10842341 DOI: 10.1016/j.neuron.2023.09.036] [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: 03/24/2023] [Revised: 07/21/2023] [Accepted: 09/26/2023] [Indexed: 10/22/2023]
Abstract
One of the more transformative findings in human genetics was the discovery that the expansion of unstable nucleotide repeats underlies a group of inherited neurological diseases. A subset of these unstable repeat neurodegenerative diseases is due to the expansion of a CAG trinucleotide repeat encoding a stretch of glutamines, i.e., the polyglutamine (polyQ) repeat neurodegenerative diseases. Among the CAG/polyQ repeat diseases are Huntington's disease (HD) and spinocerebellar ataxia type 1 (SCA1), in which the expansions are within widely expressed proteins. Although both HD and SCA1 are autosomal dominantly inherited, and both typically cause mid- to late-life-onset movement disorders with cognitive decline, they each are characterized by distinct clinical characteristics and predominant sites of neuropathology. Importantly, the respective affected proteins, Huntingtin (HTT, HD) and Ataxin 1 (ATXN1, SCA1), have unique functions and biological properties. Here, we review HD and SCA1 with a focus on how their disease-specific and shared features may provide informative insights.
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Affiliation(s)
- Leslie M Thompson
- Department of Psychiatry and Human Behavior, Department of Neurobiology and Behavior, Department of Biological Chemistry, Institute of Memory Impairments and Neurological Disorders, Sue and Bill Gross Stem Cell Center, University of California Irvine, Irvine, CA 92697, USA
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, Institute for Translational Neuroscience, University of Minnesota, Minneapolis and Saint Paul, MN 55455, USA.
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Laundos TL, Li S, Cheang E, De Santis R, Piccolo FM, Brivanlou AH. Huntingtin CAG-expansion mutation results in a dominant negative effect. Front Cell Dev Biol 2023; 11:1252521. [PMID: 37727506 PMCID: PMC10505792 DOI: 10.3389/fcell.2023.1252521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 08/14/2023] [Indexed: 09/21/2023] Open
Abstract
Introduction: Huntington's disease (HD) remains an incurable and fatal neurodegenerative disease long after CAG-expansion mutation in the huntingtin gene (HTT) was identified as the cause. The underlying pathological mechanism, whether HTT loss of function or gain of toxicity results from mutation, remains a matter of debate. Methods: In this study, we genetically modulated wild-type or mutant HTT expression levels in isogenic human embryonic stem cells to systematically investigate their contribution to HD-specific phenotypes. Results: Using highly reproducible and quantifiable in vitro micropattern-based assays, we observed comparable phenotypes with HD mutation and HTT depletion. However, halving endogenous wild-type HTT levels did not strongly recapitulate the HD phenotypes, arguing against a classical loss of function mechanism. Remarkably, expression of CAG-expanded HTT in non-HD cells induced HD like phenotypes akin to HTT depletion. Discussion: By corollary, these results indicate a dominant negative effect of mutated HTT on its wild-type counterpart. Complementation with additional copies of wild-type HTT ameliorated the HD-associated phenotypes, strongly supporting a classical dominant negative mechanism. Understanding the molecular basis of this dominant negative effect will guide the development of efficient clinical strategies to counteract the deleterious impact of mutant HTT on the wild-type HTT function.
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Affiliation(s)
- Tiago L. Laundos
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
- ICBAS—Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
- i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Porto, Portugal
| | - Shu Li
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
| | - Eric Cheang
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
| | - Riccardo De Santis
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
| | - Francesco M. Piccolo
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
| | - Ali H. Brivanlou
- Laboratory of Synthetic Embryology, The Rockefeller University, New York City, NY, United States
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Abstract
Neurodegenerative diseases are characterized by the progressive loss of structure or function of neurons. In this Spotlight, we explore the idea that genetic forms of neurodegenerative disorders might be rooted in neural development. Focusing on Alzheimer's, Parkinson's and Huntington's disease, we first provide a brief overview of the pathology for these diseases. Although neurodegenerative diseases are generally thought of as late-onset diseases, we discuss recent evidence promoting the notion that they might be considered neurodevelopmental disorders. With this view in mind, we consider the suitability of animal models for studying these diseases, highlighting human-specific features of human brain development. We conclude by proposing that one such feature, human-specific regulation of neurogenic time, might be key to understanding the etiology and pathophysiology of human neurodegenerative disease.
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Affiliation(s)
- Khadijeh Shabani
- Institut du Cerveau – Paris Brain Institute – ICM, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, 75013 Paris, France
| | - Bassem A. Hassan
- Institut du Cerveau – Paris Brain Institute – ICM, Sorbonne Université, Inserm, CNRS, Hôpital Pitié-Salpêtrière, 75013 Paris, France
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Sturchio A, Duker AP, Muñoz-Sanjuan I, Espay AJ. Subtyping monogenic disorders: Huntington disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 193:171-184. [PMID: 36803810 DOI: 10.1016/b978-0-323-85555-6.00003-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Huntington disease is a highly disabling neurodegenerative disease characterized by psychiatric, cognitive, and motor deficits. The causal genetic mutation in huntingtin (Htt, also known as IT15), located on chromosome 4p16.3, leads to an expansion of a triplet coding for polyglutamine. The expansion is invariably associated with the disease when >39 repeats. Htt encodes for the protein huntingtin (HTT), which carries out many essential biological functions in the cell, in particular in the nervous system. The precise mechanism of toxicity is not known. Based on a one-gene-one-disease framework, the prevailing hypothesis ascribes toxicity to the universal aggregation of HTT. However, the aggregation process into mutant huntingtin (mHTT) is associated with a reduction of the levels of wild-type HTT. A loss of wild-type HTT may plausibly be pathogenic, contributing to the disease onset and progressive neurodegeneration. Moreover, many other biological pathways are altered in Huntington disease, such as in the autophagic system, mitochondria, and essential proteins beyond HTT, potentially explaining biological and clinical differences among affected individuals. As one gene does not mean one disease, future efforts at identifying specific Huntington subtypes are important to design biologically tailored therapeutic approaches that correct the corresponding biological pathways-rather than continuing to exclusively target the common denominator of HTT aggregation for elimination.
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Affiliation(s)
- Andrea Sturchio
- James J. and Joan A. Gardner Family Center for Parkinson's disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States; Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, Stockholm, Sweden.
| | - Andrew P Duker
- James J. and Joan A. Gardner Family Center for Parkinson's disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States
| | | | - Alberto J Espay
- James J. and Joan A. Gardner Family Center for Parkinson's disease and Movement Disorders, Department of Neurology, University of Cincinnati, Cincinnati, OH, United States.
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Stronati E, Giraldez S, Huang L, Abraham E, McGuire GR, Hsu HT, Jones KA, Estarás C. YAP1 regulates the self-organized fate patterning of hESC-derived gastruloids. Stem Cell Reports 2022; 17:211-220. [PMID: 35063126 PMCID: PMC8828531 DOI: 10.1016/j.stemcr.2021.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 11/24/2022] Open
Abstract
The gastrulation process relies on complex interactions between developmental signaling pathways that are not completely understood. Here, we interrogated the contribution of the Hippo signaling effector YAP1 to the formation of the three germ layers by analyzing human embryonic stem cell (hESC)-derived 2D-micropatterned gastruloids. YAP1 knockout gastruloids display a reduced ectoderm layer and enlarged mesoderm and endoderm layers compared with wild type. Furthermore, our epigenome and transcriptome analysis revealed that YAP1 attenuates Nodal signaling by directly repressing the chromatin accessibility and transcription of key genes in the Nodal pathway, including the NODAL and FOXH1 genes. Hence, in the absence of YAP1, hyperactive Nodal signaling retains SMAD2/3 in the nuclei, impeding ectoderm differentiation of hESCs. Thus, our work revealed that YAP1 is a master regulator of Nodal signaling, essential for instructing germ layer fate patterning in human gastruloids. YAP1 deletion compromises cell-fate patterning of hESC-derived 2D gastruloids YAP1 is required for ectoderm differentiation in hESCs YAP1 transcriptionally represses Nodal signaling genes during ectoderm induction Reducing Nodal signaling rescues YAP1 knockout gastrulation defects
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