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Lewis SA, Bakhtiari S, Forstrom J, Bayat A, Bilan F, Le Guyader G, Alkhunaizi E, Vernon H, Padilla-Lopez SR, Kruer MC. AGAP1-associated endolysosomal trafficking abnormalities link gene-environment interactions in neurodevelopmental disorders. Dis Model Mech 2023; 16:dmm049838. [PMID: 37470098 PMCID: PMC10548112 DOI: 10.1242/dmm.049838] [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: 08/16/2022] [Accepted: 07/13/2023] [Indexed: 07/21/2023] Open
Abstract
AGAP1 is an Arf1 GTPase-activating protein that regulates endolysosomal trafficking. Damaging variants have been linked to cerebral palsy and autism. We report three new cases in which individuals had microdeletion variants in AGAP1. The affected individuals had intellectual disability (3/3), autism (3/3), dystonia with axial hypotonia (1/3), abnormalities of brain maturation (1/3), growth impairment (2/3) and facial dysmorphism (2/3). We investigated mechanisms potentially underlying AGAP1 variant-mediated neurodevelopmental impairments using the Drosophila ortholog CenG1a. We discovered reduced axon terminal size, increased neuronal endosome abundance and elevated autophagy compared to those in controls. Given potential incomplete penetrance, we assessed gene-environment interactions. We found basal elevation in the phosphorylation of the integrated stress-response protein eIF2α (or eIF2A) and inability to further increase eIF2α phosphorylation with subsequent cytotoxic stressors. CenG1a-mutant flies had increased lethality from exposure to environmental insults. We propose a model wherein disruption of AGAP1 function impairs endolysosomal trafficking, chronically activating the integrated stress response and leaving AGAP1-deficient cells susceptible to a variety of second-hit cytotoxic stressors. This model may have broader applicability beyond AGAP1 in instances where both genetic and environmental insults co-occur in individuals with neurodevelopmental disorders.
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Affiliation(s)
- Sara A. Lewis
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Jacob Forstrom
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Allan Bayat
- Institute for Regional Health Services, University of Southern Denmark, 5230 Odense, Denmark
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, 4293 Dianalund, Denmark
| | - Frédéric Bilan
- Service de Génétique, CHU de Poitiers, 86000 Poitiers, France
- Laboratoire de Neurosciences Experimentales et Cliniques, INSERM U1084, 86000 Poitiers, France
| | - Gwenaël Le Guyader
- Service de Génétique, CHU de Poitiers, 86000 Poitiers, France
- Laboratoire de Neurosciences Experimentales et Cliniques, INSERM U1084, 86000 Poitiers, France
| | - Ebba Alkhunaizi
- Department of Medical Genetics, North York General Hospital, Toronto, ON M3J0K2, Canada
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON M3J0K2, Canada
| | - Hilary Vernon
- Department of Genetic Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Sergio R. Padilla-Lopez
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Michael C. Kruer
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85016, USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
- Programs in Neuroscience, Molecular & Cellular Biology, and Biomedical Informatics, Arizona State University, Tempe, AZ 85287, USA
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Lewis SA, Bakhtiari S, Forstrom J, Bayat A, Bilan F, Le Guyader G, Alkhunaizi E, Vernon H, Padilla-Lopez SR, Kruer MC. AGAP1-associated endolysosomal trafficking abnormalities link gene-environment interactions in a neurodevelopmental disorder. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.31.526497. [PMID: 36778426 PMCID: PMC9915612 DOI: 10.1101/2023.01.31.526497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
AGAP1 is an Arf1 GAP that regulates endolysosomal trafficking. Damaging variants have been linked to cerebral palsy and autism. We report 3 new individuals with microdeletion variants in AGAP1 . Affected individuals have intellectual disability (3/3), autism (3/3), dystonia with axial hypotonia (1/3), abnormalities of brain maturation (1/3), growth impairment (2/3) and facial dysmorphism (2/3). We investigated mechanisms potentially underlying AGAP1 neurodevelopmental impairments using the Drosophila ortholog, CenG1a . We discovered reduced axon terminal size, increased neuronal endosome abundance, and elevated autophagy at baseline. Given potential incomplete penetrance, we assessed gene-environment interactions. We found basal elevation in phosphorylation of the integrated stress-response protein eIF2α and inability to further increase eIF2α-P with subsequent cytotoxic stressors. CenG1a -mutant flies have increased lethality from exposure to environmental insults. We propose a model wherein disruption of AGAP1 function impairs endolysosomal trafficking, chronically activating the integrated stress response, and leaving AGAP1-deficient cells susceptible to a variety of second hit cytotoxic stressors. This model may have broader applicability beyond AGAP1 in instances where both genetic and environmental insults co-occur in individuals with neurodevelopmental disorders. Summary statement We describe 3 additional patients with heterozygous AGAP1 deletion variants and use a loss of function Drosophila model to identify defects in synaptic morphology with increased endosomal sequestration, chronic autophagy induction, basal activation of eIF2α-P, and sensitivity to environmental stressors.
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Affiliation(s)
- Sara A. Lewis
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, AZ USA
| | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, AZ USA
| | - Jacob Forstrom
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, AZ USA
| | - Allan Bayat
- Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
| | - Frédéric Bilan
- Service de Génétique, CHU de Poitiers
- Laboratoire de Neurosciences Experimentales et Cliniques, INSERM U1084, Poitiers, France
| | - Gwenaël Le Guyader
- Service de Génétique, CHU de Poitiers
- Laboratoire de Neurosciences Experimentales et Cliniques, INSERM U1084, Poitiers, France
| | - Ebba Alkhunaizi
- Department of Medical Genetics, North York General Hospital, Toronto, Ontario, Canada
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Hilary Vernon
- Department of Genetic Medicine, Johns Hopkins University, Baltimore, MD USA
| | - Sergio R. Padilla-Lopez
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, AZ USA
| | - Michael C. Kruer
- Pediatric Movement Disorders Program, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ USA
- Departments of Child Health, Neurology, Genetics and Cellular & Molecular Medicine, University of Arizona College of Medicine Phoenix, AZ USA
- Programs in Neuroscience, Molecular & Cellular Biology, and Biomedical Informatics, Arizona State University, Tempe, AZ USA
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Wakabayashi S, Sawamura N, Voelzmann A, Broemer M, Asahi T, Hoch M. Ohgata, the Single Drosophila Ortholog of Human Cereblon, Regulates Insulin Signaling-dependent Organismic Growth. J Biol Chem 2016; 291:25120-25132. [PMID: 27702999 PMCID: PMC5122779 DOI: 10.1074/jbc.m116.757823] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Indexed: 11/06/2022] Open
Abstract
Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that is highly conserved in animals and plants. CRBN proteins have been implicated in various biological processes such as development, metabolism, learning, and memory formation, and their impairment has been linked to autosomal recessive non-syndromic intellectual disability and cancer. Furthermore, human CRBN was identified as the primary target of thalidomide teratogenicity. Data on functional analysis of CRBN family members in vivo, however, are still scarce. Here we identify Ohgata (OHGT), the Drosophila ortholog of CRBN, as a regulator of insulin signaling-mediated growth. Using ohgt mutants that we generated by targeted mutagenesis, we show that its loss results in increased body weight and organ size without changes of the body proportions. We demonstrate that ohgt knockdown in the fat body, an organ analogous to mammalian liver and adipose tissue, phenocopies the growth phenotypes. We further show that overgrowth is due to an elevation of insulin signaling in ohgt mutants and to the down-regulation of inhibitory cofactors of circulating Drosophila insulin-like peptides (DILPs), named acid-labile subunit and imaginal morphogenesis protein-late 2. The two inhibitory proteins were previously shown to be components of a heterotrimeric complex with growth-promoting DILP2 and DILP5. Our study reveals OHGT as a novel regulator of insulin-dependent organismic growth in Drosophila.
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Affiliation(s)
- Satoru Wakabayashi
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan
| | - Naoya Sawamura
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan,
- the Research Organization for Nano-life Innovation, Waseda University, Shinjuku, Tokyo 162-0041, Japan
| | - André Voelzmann
- the Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Meike Broemer
- the German Center for Neurodegenerative Diseases (DZNE), c/o Life and Medical Sciences (LIMES) Institute, Carl-Troll-Strasse 31, 53115 Bonn, Germany, and
| | - Toru Asahi
- From the Faculty of Science and Engineering, Waseda University, TWIns, 2-2 Wakamatsu, Shinjuku, Tokyo 162-8480, Japan,
- the Research Organization for Nano-life Innovation, Waseda University, Shinjuku, Tokyo 162-0041, Japan
| | - Michael Hoch
- Program Unit Development, Genetics and Molecular Physiology, Laboratory for Molecular Developmental Biology, LIMES Institute, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
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Llorens JV, Metzendorf C, Missirlis F, Lind MI. Mitochondrial iron supply is required for the developmental pulse of ecdysone biosynthesis that initiates metamorphosis in Drosophila melanogaster. J Biol Inorg Chem 2015; 20:1229-38. [PMID: 26468126 DOI: 10.1007/s00775-015-1302-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/05/2015] [Indexed: 12/23/2022]
Abstract
Synthesis of ecdysone, the key hormone that signals the termination of larval growth and the initiation of metamorphosis in insects, is carried out in the prothoracic gland by an array of iron-containing cytochrome P450s, encoded by the halloween genes. Interference, either with iron-sulfur cluster biogenesis in the prothoracic gland or with the ferredoxins that supply electrons for steroidogenesis, causes a block in ecdysone synthesis and developmental arrest in the third instar larval stage. Here we show that mutants in Drosophila mitoferrin (dmfrn), the gene encoding a mitochondrial carrier protein implicated in mitochondrial iron import, fail to grow and initiate metamorphosis under dietary iron depletion or when ferritin function is partially compromised. In mutant dmfrn larvae reared under iron replete conditions, the expression of halloween genes is increased and 20-hydroxyecdysone (20E), the active form of ecdysone, is synthesized. In contrast, addition of an iron chelator to the diet of mutant dmfrn larvae disrupts 20E synthesis. Dietary addition of 20E has little effect on the growth defects, but enables approximately one-third of the iron-deprived dmfrn larvae to successfully turn into pupae and, in a smaller percentage, into adults. This partial rescue is not observed with dietary supply of ecdysone's precursor 7-dehydrocholesterol, a precursor in the ecdysone biosynthetic pathway. The findings reported here support the notion that a physiological supply of mitochondrial iron for the synthesis of iron-sulfur clusters and heme is required in the prothoracic glands of insect larvae for steroidogenesis. Furthermore, mitochondrial iron is also essential for normal larval growth.
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Affiliation(s)
- Jose V Llorens
- Department of Comparative Physiology, Uppsala University, Norbyvägen 18A, Uppsala, Sweden
| | - Christoph Metzendorf
- Heidelberg University Biochemistry Center (BZH), University of Heidelberg, Im Neuenheimer Feld 328, Heidelberg, Germany
| | - Fanis Missirlis
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, Av. IPN 2508, Mexico City, Mexico.
| | - Maria I Lind
- Department of Comparative Physiology, Uppsala University, Norbyvägen 18A, Uppsala, Sweden.
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Carnes MU, Campbell T, Huang W, Butler DG, Carbone MA, Duncan LH, Harbajan SV, King EM, Peterson KR, Weitzel A, Zhou S, Mackay TFC. The Genomic Basis of Postponed Senescence in Drosophila melanogaster. PLoS One 2015; 10:e0138569. [PMID: 26378456 PMCID: PMC4574564 DOI: 10.1371/journal.pone.0138569] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/01/2015] [Indexed: 12/30/2022] Open
Abstract
Natural populations harbor considerable genetic variation for lifespan. While evolutionary theory provides general explanations for the existence of this variation, our knowledge of the genes harboring naturally occurring polymorphisms affecting lifespan is limited. Here, we assessed the genetic divergence between five Drosophila melanogaster lines selected for postponed senescence for over 170 generations (O lines) and five lines from the same base population maintained at a two week generation interval for over 850 generations (B lines). On average, O lines live 70% longer than B lines, are more productive at all ages, and have delayed senescence for other traits than reproduction. We performed population sequencing of pools of individuals from all B and O lines and identified 6,394 genetically divergent variants in or near 1,928 genes at a false discovery rate of 0.068. A 2.6 Mb region at the tip of the X chromosome contained many variants fixed for alternative alleles in the two populations, suggestive of a hard selective sweep. We also assessed genome wide gene expression of O and B lines at one and five weeks of age using RNA sequencing and identified genes with significant (false discovery rate < 0.05) effects on gene expression with age, population and the age by population interaction, separately for each sex. We identified transcripts that exhibited the transcriptional signature of postponed senescence and integrated the gene expression and genetic divergence data to identify 98 (175) top candidate genes in females (males) affecting postponed senescence and increased lifespan. While several of these genes have been previously associated with Drosophila lifespan, most are novel and constitute a rich resource for future functional validation.
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Affiliation(s)
- Megan Ulmer Carnes
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Terry Campbell
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Wen Huang
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; Program in Genetics, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Daniel G Butler
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Mary Anna Carbone
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; Program in Genetics, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Laura H Duncan
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Sasha V Harbajan
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Edward M King
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Kara R Peterson
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Alexander Weitzel
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Shanshan Zhou
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; Program in Genetics, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
| | - Trudy F C Mackay
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; Program in Genetics, North Carolina State University, Raleigh, North Carolina, 27695, United States of America; W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, 27695, United States of America
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Yan Y, Wang H, Chen H, Lindström-Battle A, Jiao R. Ecdysone and Insulin Signaling Play Essential Roles in Readjusting the Altered Body Size Caused by the dGPAT4 Mutation in Drosophila. J Genet Genomics 2015; 42:487-94. [DOI: 10.1016/j.jgg.2015.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 06/04/2015] [Accepted: 06/04/2015] [Indexed: 12/19/2022]
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