1
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Zaqout S, Kaindl AM. Autosomal Recessive Primary Microcephaly: Not Just a Small Brain. Front Cell Dev Biol 2022; 9:784700. [PMID: 35111754 PMCID: PMC8802810 DOI: 10.3389/fcell.2021.784700] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/01/2021] [Indexed: 02/06/2023] Open
Abstract
Microcephaly or reduced head circumference results from a multitude of abnormal developmental processes affecting brain growth and/or leading to brain atrophy. Autosomal recessive primary microcephaly (MCPH) is the prototype of isolated primary (congenital) microcephaly, affecting predominantly the cerebral cortex. For MCPH, an accelerating number of mutated genes emerge annually, and they are involved in crucial steps of neurogenesis. In this review article, we provide a deeper look into the microcephalic MCPH brain. We explore cytoarchitecture focusing on the cerebral cortex and discuss diverse processes occurring at the level of neural progenitors, early generated and mature neurons, and glial cells. We aim to thereby give an overview of current knowledge in MCPH phenotype and normal brain growth.
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Affiliation(s)
- Sami Zaqout
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
- Biomedical and Pharmaceutical Research Unit, QU Health, Qatar University, Doha, Qatar
| | - Angela M. Kaindl
- Institute of Cell and Neurobiology, Charité—Universitätsmedizin Berlin, Berlin, Germany
- Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Charité—Universitätsmedizin Berlin, Berlin, Germany
- Department of Pediatric Neurology, Charité—Universitätsmedizin Berlin, Berlin, Germany
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2
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Bedont JL, Toda H, Shi M, Park CH, Quake C, Stein C, Kolesnik A, Sehgal A. Short and long sleeping mutants reveal links between sleep and macroautophagy. eLife 2021; 10:64140. [PMID: 34085929 PMCID: PMC8177895 DOI: 10.7554/elife.64140] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 05/20/2021] [Indexed: 02/03/2023] Open
Abstract
Sleep is a conserved and essential behavior, but its mechanistic and functional underpinnings remain poorly defined. Through unbiased genetic screening in Drosophila, we discovered a novel short-sleep mutant we named argus. Positional cloning and subsequent complementation, CRISPR/Cas9 knock-out, and RNAi studies identified Argus as a transmembrane protein that acts in adult peptidergic neurons to regulate sleep. argus mutants accumulate undigested Atg8a(+) autophagosomes, and genetic manipulations impeding autophagosome formation suppress argus sleep phenotypes, indicating that autophagosome accumulation drives argus short-sleep. Conversely, a blue cheese neurodegenerative mutant that impairs autophagosome formation was identified independently as a gain-of-sleep mutant, and targeted RNAi screens identified additional genes involved in autophagosome formation whose knockdown increases sleep. Finally, autophagosomes normally accumulate during the daytime and nighttime sleep deprivation extends this accumulation into the following morning, while daytime gaboxadol feeding promotes sleep and reduces autophagosome accumulation at nightfall. In sum, our results paradoxically demonstrate that wakefulness increases and sleep decreases autophagosome levels under unperturbed conditions, yet strong and sustained upregulation of autophagosomes decreases sleep, whereas strong and sustained downregulation of autophagosomes increases sleep. The complex relationship between sleep and autophagy suggested by our findings may have implications for pathological states including chronic sleep disorders and neurodegeneration, as well as for integration of sleep need with other homeostats, such as under conditions of starvation.
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Affiliation(s)
- Joseph L Bedont
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Hirofumi Toda
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Mi Shi
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Christine H Park
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Christine Quake
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Carly Stein
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Anna Kolesnik
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States
| | - Amita Sehgal
- Chronobiology and Sleep Institute, Perelman Medical School of University of Pennsylvania, Philadelphia, United States.,Howard Hughes Medical Institute, Philadelphia, United States
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3
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Duan X, Tong C. Autophagy in Drosophila and Zebrafish. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1208:333-356. [PMID: 34260032 DOI: 10.1007/978-981-16-2830-6_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Autophagy is a highly conserved cellular process that delivers cellular contents to the lysosome for degradation. It not only serves as a bulk degradation system for various cytoplasmic components but also functions selectively to clear damaged organelles, aggregated proteins, and invading pathogens (Feng et al., Cell Res 24:24-41, 2014; Galluzzi et al., EMBO J 36:1811-36, 2017; Klionsky et al., Autophagy 12:1-222, 2016). The malfunction of autophagy leads to multiple developmental defects and diseases (Mizushima et al., Nature 451:1069-75, 2008). Drosophila and zebrafish are higher metazoan model systems with sophisticated genetic tools readily available, which make it possible to dissect the autophagic processes and to understand the physiological functions of autophagy (Lorincz et al., Cells 6:22, 2017a; Mathai et al., Cells 6:21, 2017; Zhang and Baehrecke, Trends Cell Biol 25:376-87, 2015). In this chapter, we will discuss recent progress that has been made in the autophagic field by using these animal models. We will focus on the protein machineries required for autophagosome formation and maturation as well as the physiological roles of autophagy in both Drosophila and zebrafish.
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Affiliation(s)
- Xiuying Duan
- MOE Key Laboratory for Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chao Tong
- MOE Key Laboratory for Biosystems Homeostasis and Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, China. .,The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
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4
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Matiytsiv NP, Chernyk YI. Drosophila melanogaster as a Model System for the Study of Human Neuropathy and the Testing of Neuroprotectors. CYTOL GENET+ 2020. [DOI: 10.3103/s0095452720030081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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5
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Sim J, Osborne KA, Argudo García I, Matysik AS, Kraut R. The BEACH Domain Is Critical for Blue Cheese Function in a Spatial and Epistatic Autophagy Hierarchy. Front Cell Dev Biol 2019; 7:129. [PMID: 31428609 PMCID: PMC6688705 DOI: 10.3389/fcell.2019.00129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 07/02/2019] [Indexed: 01/26/2023] Open
Abstract
Drosophila blue cheese (bchs) encodes a BEACH domain adaptor protein that, like its human homolog ALFY, promotes clearance of aggregated proteins through its interaction with Atg5 and p62. bchs mutations lead to age-dependent accumulation of ubiquitinated inclusions and progressive neurodegeneration in the fly brain, but neither the influence of autophagy on bchs-related degeneration, nor bchs’ placement in the autophagic hierarchy have been shown. We present epistatic evidence in a well-defined larval motor neuron paradigm that in bchs mutants, synaptic accumulation of ubiquitinated aggregates and neuronal death can be rescued by pharmacologically amplifying autophagic initiation. Further, pharmacological rescue requires at least one intact BEACH-containing isoform of the two identified in this study. Genetically augmenting a late step in autophagy, however, rescues even a strong mutation which retains only a third, non-BEACH containing isoform. Using living primary larval brain neurons, we elucidate the primary defect in bchs to be an excess of early autophagic compartments and a deficit in mature compartments. Conversely, rescuing the mutants by full-length Bchs over-expression induces mature compartment proliferation and rescues neuronal death. Surprisingly, only the longest Bchs isoform colocalizes well with autophagosomes, and shuttles between different vesicular locations depending on the type of autophagic impetus applied. Our results are consistent with Bchs promoting autophagic maturation, and the BEACH domain being required for this function.
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Affiliation(s)
- Joan Sim
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Kathleen A Osborne
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Irene Argudo García
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - Artur S Matysik
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Rachel Kraut
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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6
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Beyond autophagy: a novel role for autism-linked Wdfy3 in brain mitophagy. Sci Rep 2018; 8:11348. [PMID: 30054502 PMCID: PMC6063930 DOI: 10.1038/s41598-018-29421-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/05/2018] [Indexed: 01/12/2023] Open
Abstract
WD repeat and FYVE domain-containing 3 (WDFY3; also known as Autophagy-Linked FYVE or Alfy) is an identified intellectual disability, developmental delay and autism risk gene. This gene encodes for a scaffolding protein that is expressed in both the developing and adult central nervous system and required for autophagy and aggrephagy with yet unexplored roles in mitophagy. Given that mitochondrial trafficking, dynamics and remodeling have key roles in synaptic plasticity, we tested the role of Wdfy3 on brain bioenergetics by using Wdfy3+/lacZ mice, the only known Wdfy3 mutant animal model with overt neurodevelopmental anomalies that survive to adulthood. We found that Wdfy3 is required for sustaining brain bioenergetics and morphology via mitophagy. Decreased mitochondrial quality control by conventional mitophagy was partly compensated for by the increased formation of mitochondria-derived vesicles (MDV) targeted to lysosomal degradation (micromitophagy). These observations, extended through proteomic analysis of mitochondria-enriched cortical fractions, showed significant enrichment for pathways associated with mitophagy, mitochondrial transport and axon guidance via semaphorin, Robo, L1cam and Eph-ephrin signaling. Collectively, our findings support a critical role for Wdfy3 in mitochondrial homeostasis with implications for neuron differentiation, neurodevelopment and age-dependent neurodegeneration.
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7
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Hebbar S, Khandelwal A, Jayashree R, Hindle SJ, Chiang YN, Yew JY, Sweeney ST, Schwudke D. Lipid metabolic perturbation is an early-onset phenotype in adult spinster mutants: a Drosophila model for lysosomal storage disorders. Mol Biol Cell 2017; 28:3728-3740. [PMID: 29046397 PMCID: PMC5739291 DOI: 10.1091/mbc.e16-09-0674] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/10/2017] [Accepted: 10/11/2017] [Indexed: 02/06/2023] Open
Abstract
Intracellular accumulation of lipids and swollen dysfunctional lysosomes are linked to several neurodegenerative diseases, including lysosomal storage disorders (LSD). Detailed characterization of lipid metabolic changes in relation to the onset and progression of neurodegeneration is currently missing. We systematically analyzed lipid perturbations in spinster (spin) mutants, a Drosophila model of LSD-like neurodegeneration. Our results highlight an imbalance in brain ceramide and sphingosine in the early stages of neurodegeneration, preceding the accumulation of endomembranous structures, manifestation of altered behavior, and buildup of lipofuscin. Manipulating levels of ceramidase and altering these lipids in spin mutants allowed us to conclude that ceramide homeostasis is the driving force in disease progression and is integral to spin function in the adult nervous system. We identified 29 novel physical interaction partners of Spin and focused on the lipid carrier protein, Lipophorin (Lpp). A subset of Lpp and Spin colocalize in the brain and within organs specialized for lipid metabolism (fat bodies and oenocytes). Reduced Lpp protein was observed in spin mutant tissues. Finally, increased levels of lipid metabolites produced by oenocytes in spin mutants allude to a functional interaction between Spin and Lpp, underscoring the systemic nature of lipid perturbation in LSD.
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Affiliation(s)
- Sarita Hebbar
- National Center for Biological Sciences, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - Avinash Khandelwal
- National Center for Biological Sciences, Tata Institute for Fundamental Research, Bangalore 560065, India
| | - R Jayashree
- Centre for Cellular and Molecular Platforms (C-CAMP), Proteomics Facility, Bangalore 560065, India
| | | | | | - Joanne Y Yew
- Pacific Biosciences Research Center, University of Hawai'i at Ma-noa, Honolulu, HI 96822
| | - Sean T Sweeney
- Department of Biology, University of York, York YO10 5DD, UK
| | - Dominik Schwudke
- National Center for Biological Sciences, Tata Institute for Fundamental Research, Bangalore 560065, India
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8
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Kim M, Ho A, Lee JH. Autophagy and Human Neurodegenerative Diseases-A Fly's Perspective. Int J Mol Sci 2017; 18:ijms18071596. [PMID: 28737703 PMCID: PMC5536083 DOI: 10.3390/ijms18071596] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/12/2017] [Accepted: 07/21/2017] [Indexed: 12/18/2022] Open
Abstract
Neurodegenerative diseases in humans are frequently associated with prominent accumulation of toxic protein inclusions and defective organelles. Autophagy is a process of bulk lysosomal degradation that eliminates these harmful substances and maintains the subcellular environmental quality. In support of autophagy's importance in neuronal homeostasis, several genetic mutations that interfere with autophagic processes were found to be associated with familial neurodegenerative disorders. In addition, genetic mutations in autophagy-regulating genes provoked neurodegenerative phenotypes in animal models. The Drosophila model significantly contributed to these recent developments, which led to the theory that autophagy dysregulation is one of the major underlying causes of human neurodegenerative disorders. In the current review, we discuss how studies using Drosophila enhanced our understanding of the relationship between autophagy and neurodegenerative processes.
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Affiliation(s)
- Myungjin Kim
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Allison Ho
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Jun Hee Lee
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.
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9
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LRBA is Essential for Allogeneic Responses in Bone Marrow Transplantation. Sci Rep 2016; 6:36568. [PMID: 27824136 PMCID: PMC5099895 DOI: 10.1038/srep36568] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 10/18/2016] [Indexed: 12/25/2022] Open
Abstract
The PH-BEACH-WD40 (PBW) protein family members play a role in coordinating receptor signaling and intracellular vesicle trafficking. LPS-Responsive-Beige-like Anchor (LRBA) is a PBW protein whose immune function remains elusive. Here we show that LRBA-null mice are viable, but exhibit compromised rejection of allogeneic, xenogeneic and missing self bone-marrow grafts. Further, we demonstrate that LRBA-null Natural Killer (NK) cells exhibit impaired signaling by the key NK activating receptors, NKp46 and NKG2D. However, induction of IFN-γ by cytokines remains intact, indicating LRBA selectively facilitates signals by receptors for ligands expressed on the surface of NK targets. Surprisingly, LRBA limits immunoregulatory cell numbers in tissues where GvHD is primed or initiated, and consistent with this LRBA-null mice also demonstrate resistance to lethal GvHD. These findings demonstrate that LRBA is redundant for host longevity while being essential for both host and donor-mediated immune responses and thus represents a unique and novel molecular target in transplant immunology.
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10
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Dragich JM, Kuwajima T, Hirose-Ikeda M, Yoon MS, Eenjes E, Bosco JR, Fox LM, Lystad AH, Oo TF, Yarygina O, Mita T, Waguri S, Ichimura Y, Komatsu M, Simonsen A, Burke RE, Mason CA, Yamamoto A. Autophagy linked FYVE (Alfy/WDFY3) is required for establishing neuronal connectivity in the mammalian brain. eLife 2016; 5. [PMID: 27648578 PMCID: PMC5030082 DOI: 10.7554/elife.14810] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 08/25/2016] [Indexed: 12/23/2022] Open
Abstract
The regulation of protein degradation is essential for maintaining the appropriate environment to coordinate complex cell signaling events and to promote cellular remodeling. The Autophagy linked FYVE protein (Alfy), previously identified as a molecular scaffold between the ubiquitinated cargo and the autophagic machinery, is highly expressed in the developing central nervous system, indicating that this pathway may have yet unexplored roles in neurodevelopment. To examine this possibility, we used mouse genetics to eliminate Alfy expression. We report that this evolutionarily conserved protein is required for the formation of axonal tracts throughout the brain and spinal cord, including the formation of the major forebrain commissures. Consistent with a phenotype reflecting a failure in axon guidance, the loss of Alfy in mice disrupts localization of glial guidepost cells, and attenuates axon outgrowth in response to Netrin-1. These findings further support the growing indication that macroautophagy plays a key role in the developing CNS.
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Affiliation(s)
- Joanna M Dragich
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Takaaki Kuwajima
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Cell Biology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Megumi Hirose-Ikeda
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Michael S Yoon
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Evelien Eenjes
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Joan R Bosco
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Leora M Fox
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States.,Doctoral Program in Neurobiology and Behavior, Columbia University, New York, United States
| | - Alf H Lystad
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Tinmarla F Oo
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Olga Yarygina
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Tomohiro Mita
- The Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Satoshi Waguri
- Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Yoshinobu Ichimura
- The Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Masaaki Komatsu
- The Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Anne Simonsen
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Robert E Burke
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Cell Biology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Carol A Mason
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Cell Biology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Neuroscience, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, New York, United States
| | - Ai Yamamoto
- Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, United States.,Department of Cell Biology, College of Physicians and Surgeons, Columbia University, New York, United States
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11
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Abstract
Polyglutamine (polyQ) expansion within Huntingtin (Htt) causes the fatal neurodegenerative disorder Huntington’s Disease (HD). Although Htt is ubiquitously expressed and conserved from Drosophila to humans, its normal biological function is still being elucidated. Here we characterize a role for the Drosophila Htt homolog (dHtt) in fast axonal transport (FAT). Generation and expression of transgenic dHtt-mRFP and human Htt-mRFP fusion proteins in Drosophila revealed co-localization with mitochondria and synaptic vesicles undergoing FAT. However, Htt was not ubiquitously associated with the transport machinery, as it was excluded from dense-core vesicles and APLIP1 containing vesicles. Quantification of cargo movement in dHtt deficient axons revealed that mitochondria and synaptic vesicles show a decrease in the distance and duration of transport, and an increase in the number of pauses. In addition, the ratio of retrograde to anterograde flux was increased in mutant animals. Densecore vesicles did not display similar defects in processivity, but did show altered retrograde to anterograde flux along axons. Given the co-localization with mitochondria and synaptic vesicles, but not dense-core vesicles, the data suggest dHtt likely acts locally at cargo interaction sites to regulate processivity. An increase in dynein heavy chain expression was also observed in dHtt mutants, suggesting that the altered flux observed for all cargo may represent secondary transport changes occurring independent of dHtt’s primary function. Expression of dHtt in a milton (HAP1) mutant background revealed that the protein does not require mitochondria or HAP1 to localize along axons, suggesting Htt has an independent mechanism for coupling with motors to regulate their processivity during axonal transport.
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Affiliation(s)
- Kurt R Weiss
- a Department of Biology , The Picower Institute for Learning and Memory, Massachusetts Institute of Technology , Cambridge , MA , USA.,b Department of Brain and Cognitive Sciences , The Picower Institute for Learning and Memory, Massachusetts Institute of Technology , Cambridge , MA , USA
| | - J Troy Littleton
- a Department of Biology , The Picower Institute for Learning and Memory, Massachusetts Institute of Technology , Cambridge , MA , USA.,b Department of Brain and Cognitive Sciences , The Picower Institute for Learning and Memory, Massachusetts Institute of Technology , Cambridge , MA , USA
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12
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Ceramides And Stress Signalling Intersect With Autophagic Defects In Neurodegenerative Drosophila blue cheese (bchs) Mutants. Sci Rep 2015; 5:15926. [PMID: 26639035 PMCID: PMC4671070 DOI: 10.1038/srep15926] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/07/2015] [Indexed: 12/19/2022] Open
Abstract
Sphingolipid metabolites are involved in the regulation of autophagy, a degradative recycling process that is required to prevent neuronal degeneration. Drosophila blue cheese mutants neurodegenerate due to perturbations in autophagic flux, and consequent accumulation of ubiquitinated aggregates. Here, we demonstrate that blue cheese mutant brains exhibit an elevation in total ceramide levels; surprisingly, however, degeneration is ameliorated when the pool of available ceramides is further increased, and exacerbated when ceramide levels are decreased by altering sphingolipid catabolism or blocking de novo synthesis. Exogenous ceramide is seen to accumulate in autophagosomes, which are fewer in number and show less efficient clearance in blue cheese mutant neurons. Sphingolipid metabolism is also shifted away from salvage toward de novo pathways, while pro-growth Akt and MAP pathways are down-regulated, and ER stress is increased. All these defects are reversed under genetic rescue conditions that increase ceramide generation from salvage pathways. This constellation of effects suggests a possible mechanism whereby the observed deficit in a potentially ceramide-releasing autophagic pathway impedes survival signaling and exacerbates neuronal death.
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13
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Hasanagic M, van Meel E, Luan S, Aurora R, Kornfeld S, Eissenberg JC. The lysosomal enzyme receptor protein (LERP) is not essential, but is implicated in lysosomal function in Drosophila melanogaster. Biol Open 2015; 4:1316-25. [PMID: 26405051 PMCID: PMC4610224 DOI: 10.1242/bio.013334] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 08/20/2015] [Indexed: 12/12/2022] Open
Abstract
The lysosomal enzyme receptor protein (LERP) of Drosophila melanogaster is the ortholog of the mammalian cation-independent mannose 6-phosphate (Man 6-P) receptor, which mediates trafficking of newly synthesized lysosomal acid hydrolases to lysosomes. However, flies lack the enzymes necessary to make the Man 6-P mark, and the amino acids implicated in Man 6-P binding by the mammalian receptor are not conserved in LERP. Thus, the function of LERP in sorting of lysosomal enzymes to lysosomes in Drosophila is unclear. Here, we analyze the consequence of LERP depletion in S2 cells and intact flies. RNAi-mediated knockdown of LERP in S2 cells had little or no effect on the cellular content or secretion of several lysosomal hydrolases. We generated a novel Lerp null mutation, Lerp(F6), which abolishes LERP protein expression. Lerp mutants have normal viability and fertility and display no overt phenotypes other than reduced body weight. Lerp mutant flies exhibit a 30-40% decrease in the level of several lysosomal hydrolases, and are hypersensitive to dietary chloroquine and starvation, consistent with impaired lysosome function. Loss of LERP also enhances an eye phenotype associated with defective autophagy. Our findings implicate Lerp in lysosome function and autophagy.
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Affiliation(s)
- Medina Hasanagic
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Eline van Meel
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Shan Luan
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA
| | - Rajeev Aurora
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Stuart Kornfeld
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Joel C Eissenberg
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA
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14
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Steffens A, Bräutigam A, Jakoby M, Hülskamp M. The BEACH Domain Protein SPIRRIG Is Essential for Arabidopsis Salt Stress Tolerance and Functions as a Regulator of Transcript Stabilization and Localization. PLoS Biol 2015; 13:e1002188. [PMID: 26133670 PMCID: PMC4489804 DOI: 10.1371/journal.pbio.1002188] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 05/26/2015] [Indexed: 12/22/2022] Open
Abstract
Members of the highly conserved class of BEACH domain containing proteins (BDCPs) have been established as broad facilitators of protein-protein interactions and membrane dynamics in the context of human diseases like albinism, bleeding diathesis, impaired cellular immunity, cancer predisposition, and neurological dysfunctions. Also, the Arabidopsis thaliana BDCP SPIRRIG (SPI) is important for membrane integrity, as spi mutants exhibit split vacuoles. In this work, we report a novel molecular function of the BDCP SPI in ribonucleoprotein particle formation. We show that SPI interacts with the P-body core component DECAPPING PROTEIN 1 (DCP1), associates to mRNA processing bodies (P-bodies), and regulates their assembly upon salt stress. The finding that spi mutants exhibit salt hypersensitivity suggests that the local function of SPI at P-bodies is of biological relevance. Transcriptome-wide analysis revealed qualitative differences in the salt stress-regulated transcriptional response of Col-0 and spi. We show that SPI regulates the salt stress-dependent post-transcriptional stabilization, cytoplasmic agglomeration, and localization to P-bodies of a subset of salt stress-regulated mRNAs. Finally, we show that the PH-BEACH domains of SPI and its human homolog FAN (Factor Associated with Neutral sphingomyelinase activation) interact with DCP1 isoforms from plants, mammals, and yeast, suggesting the evolutionary conservation of an association of BDCPs and P-bodies.
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Affiliation(s)
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Düsseldorf, Germany
- Plant Biochemistry, Heinrich Heine University, Düsseldorf, Germany
| | - Marc Jakoby
- Botanical Institute, Biocenter, Cologne University, Cologne, Germany
| | - Martin Hülskamp
- Botanical Institute, Biocenter, Cologne University, Cologne, Germany
- * E-mail:
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15
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Lee YM, Sun YH. Maintenance of glia in the optic lamina is mediated by EGFR signaling by photoreceptors in adult Drosophila. PLoS Genet 2015; 11:e1005187. [PMID: 25909451 PMCID: PMC4409299 DOI: 10.1371/journal.pgen.1005187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/31/2015] [Indexed: 01/13/2023] Open
Abstract
The late onset of neurodegeneration in humans indicates that the survival and function of cells in the nervous system must be maintained throughout adulthood. In the optic lamina of the adult Drosophila, the photoreceptor axons are surrounded by multiple types of glia. We demonstrated that the adult photoreceptors actively contribute to glia maintenance in their target field within the optic lamina. This effect is dependent on the epidermal growth factor receptor (EGFR) ligands produced by the R1-6 photoreceptors and transported to the optic lamina to act on EGFR in the lamina glia. EGFR signaling is necessary and sufficient to act in a cell-autonomous manner in the lamina glia. Our results suggest that EGFR signaling is required for the trafficking of the autophagosome/endosome to the lysosome. The loss of EGFR signaling results in cell degeneration most likely because of the accumulation of autophagosomes. Our findings provide in vivo evidence for the role of adult neurons in the maintenance of glia and a novel role for EGFR signaling in the autophagic flux. Degeneration of the nervous system can be viewed as a failure to maintain cell survival or function in the nervous system. The late onset of neurodegeneration in humans indicates that the cell survival in the nervous system must be maintained throughout our lives. Neuronal survival is maintained by neurotrophic factors in adults; however, it is unclear whether glia survival is also maintained throughout adulthood. Here, we use the Drosophila visual system as a model to address the role played by adult neurons for the active maintenance of glia. We demonstrated that the adult photoreceptors secrete a signaling molecule, which is transported to the brain to act on the lamina glia and maintain its integrity. When this signaling pathway is blocked, the lamina glia undergoes a progressive and irreversible degeneration. The primary defect occurs in the trafficking from the late endosome and autophagosome to the lysosome. This defect leads to an accumulation of autophagosomes and subsequent cell degeneration as a result of autophagy. Our findings provide in vivo evidence for a novel aspect of the neuron-glia interaction and a novel role for EGFR signaling in regulating the maintenance and degeneration of the nervous system.
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Affiliation(s)
- Yuan-Ming Lee
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Y. Henry Sun
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Institute of Genomic Sciences, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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16
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Teh OK, Hatsugai N, Tamura K, Fuji K, Tabata R, Yamaguchi K, Shingenobu S, Yamada M, Hasebe M, Sawa S, Shimada T, Hara-Nishimura I. BEACH-domain proteins act together in a cascade to mediate vacuolar protein trafficking and disease resistance in Arabidopsis. MOLECULAR PLANT 2015; 8:389-98. [PMID: 25618824 DOI: 10.1016/j.molp.2014.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/21/2014] [Accepted: 11/12/2014] [Indexed: 05/08/2023]
Abstract
Membrane trafficking to the protein storage vacuole (PSV) is a specialized process in seed plants. However, this trafficking mechanism to PSV is poorly understood. Here, we show that three types of Beige and Chediak-Higashi (BEACH)-domain proteins contribute to both vacuolar protein transport and effector-triggered immunity (ETI). We screened a green fluorescent seed (GFS) library of Arabidopsis mutants with defects in vesicle trafficking and isolated two allelic mutants gfs3 and gfs12 with a defect in seed protein transport to PSV. The gene responsible for the mutant phenotype was found to encode a putative protein belonging to group D of BEACH-domain proteins, which possess kinase domains. Disruption of other BEACH-encoding loci in the gfs12 mutant showed that BEACH homologs acted in a cascading manner for PSV trafficking. The epistatic genetic interactions observed among BEACH homologs were also found in the ETI responses of the gfs12 and gfs12 bchb-1 mutants, which showed elevated avirulent bacterial growth. The GFS12 kinase domain interacted specifically with the pleckstrin homology domain of BchC1. These results suggest that a cascade of multiple BEACH-domain proteins contributes to vacuolar protein transport and plant defense.
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Affiliation(s)
- Ooi-kock Teh
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Noriyuki Hatsugai
- Research Centre for Cooperative Projects, Hokkaido University, Kita-ku, Sapporo 060-8638, Japan
| | - Kentaro Tamura
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kentaro Fuji
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Ryo Tabata
- Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
| | - Katsushi Yamaguchi
- Functional Genomics Facility, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Shuji Shingenobu
- Functional Genomics Facility, National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Masashi Yamada
- Department of Biology and IGSP Center for Systems Biology, Duke University, Durham, NC 27708, USA
| | - Mitsuyasu Hasebe
- Division of Evolutionary Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan; School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
| | - Shinichiro Sawa
- Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan
| | - Tomoo Shimada
- Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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17
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Bakhoum MF, Bakhoum CY, Ding Z, Carlton SM, Campbell GA, Jackson GR. Evidence for autophagic gridlock in aging and neurodegeneration. Transl Res 2014; 164:1-12. [PMID: 24561013 DOI: 10.1016/j.trsl.2014.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 01/07/2014] [Accepted: 01/08/2014] [Indexed: 10/25/2022]
Abstract
Autophagy is essential to neuronal homeostasis, and its impairment is implicated in the development of neurodegenerative pathology. However, the underlying mechanisms and consequences of this phenomenon remain a matter of conjecture. We show that misexpression of human tau in Drosophila induces accumulation of autophagic intermediates with a preponderance of large vacuoles, which we term giant autophagic bodies (GABs), which are reminiscent of dysfunctional autophagic entities. Lowering basal autophagy reduces GABs, whereas increasing autophagy decreases mature autolysosomes. Induction of autophagy is also associated with rescue of the tauopathy phenotype, suggesting that formation of GABs may be a compensatory mechanism rather than a trigger of neurodegeneration. Last, we show that the peculiar Biondi bodies observed in the choroid epithelium of both elderly and Alzheimer's disease human brains express immunoreactive markers similar to those of GABs. Collectively, these data indicate that autophagic gridlock contributes to the development of pathology in aging and neurodegeneration.
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Affiliation(s)
- Mathieu F Bakhoum
- School of Medicine, The University of Texas Medical Branch at Galveston, Galveston, Tex; Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Galveston, Tex
| | - Christine Y Bakhoum
- School of Medicine, The University of Texas Medical Branch at Galveston, Galveston, Tex
| | - Zhixia Ding
- Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Galveston, Tex
| | - Susan M Carlton
- School of Medicine, The University of Texas Medical Branch at Galveston, Galveston, Tex; Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Galveston, Tex
| | - Gerald A Campbell
- School of Medicine, The University of Texas Medical Branch at Galveston, Galveston, Tex; Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, Tex
| | - George R Jackson
- Department of Neuroscience and Cell Biology, The University of Texas Medical Branch at Galveston, Galveston, Tex; Department of Neurology, The University of Texas Medical Branch at Galveston, Galveston, Tex; Department of Neurology, Baylor College of Medicine, and Parkinson's Disease Research Education and Clinical Center, Michael E. DeBakey VA Medical Center, Houston, Tex.
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18
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Abstract
Autophagy is a conserved catabolic process that delivers the cytosol and cytosolic constituents to the lysosome. Its fundamental role is to maintain cellular homeostasis and to protect cells from varying insults, including misfolded proteins and damaged organelles. Beyond these roles, the highly specialized cells of the brain have further adapted autophagic pathways to suit their distinct needs. In this review, we briefly summarize our current understanding of the different forms of autophagy and then offer a closer look at how these pathways impact neuronal and glial functions. The emerging evidence indicates that not only are autophagy pathways essential for neural health, but they have a direct impact on developmental and neurodegenerative processes. Taken together, as we unravel the complex roles autophagy pathways play, we will gain the necessary insight to modify these pathways to protect the human brain and treat neurodegenerative diseases.
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Affiliation(s)
- Ai Yamamoto
- Departments of Neurology, Pathology, and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032;
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19
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Cullinane AR, Schäffer AA, Huizing M. The BEACH is hot: a LYST of emerging roles for BEACH-domain containing proteins in human disease. Traffic 2013; 14:749-66. [PMID: 23521701 DOI: 10.1111/tra.12069] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/18/2013] [Accepted: 03/23/2013] [Indexed: 12/19/2022]
Abstract
BEACH (named after 'Beige and Chediak-Higashi') is a conserved ∼280 residue domain, present in nine human BEACH domain containing proteins (BDCPs). Most BDCPs are large, containing a PH-like domain for membrane association preceding their BEACH domain, and containing WD40 and other domains for ligand binding. Recent studies found that mutations in individual BDCPs cause several human diseases. BDCP alterations affect lysosome size (LYST and NSMAF), apoptosis (NSMAF), autophagy (LYST, WDFY3, LRBA), granule size (LYST, NBEAL2, NBEA) or synapse formation (NBEA). However, the roles of each BDCP in these membrane events remain controversial. After reviewing studies on individual BDCPs, we propose a unifying hypothesis that BDCPs act as scaffolding proteins that facilitate membrane events, including both fission and fusion, determined by their binding partners. BDCPs may also bind each other, enabling fusion or fission of vesicles that are not necessarily of the same type. Such mechanisms explain why different BDCPs may have roles in autophagy; each BDCP is specific for the cell type or the cargo, but not necessarily specific for attaching to the autophagosome. Further elucidation of these mechanisms, preferably carrying out the same experiment on multiple BDCPs, and possibly using patients' cells, may identify potential targets for therapy.
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Affiliation(s)
- Andrew R Cullinane
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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20
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Luan S, Ilvarsonn AM, Eissenberg JC. The unique GGA clathrin adaptor of Drosophila melanogaster is not essential. PLoS One 2012; 7:e45163. [PMID: 23028818 PMCID: PMC3447878 DOI: 10.1371/journal.pone.0045163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 08/17/2012] [Indexed: 01/07/2023] Open
Abstract
The Golgi-localized, γ-ear-containing, ARF binding proteins (GGAs) are a highly conserved family of monomeric clathrin adaptor proteins implicated in clathrin-mediated protein sorting between the trans-Golgi network and endosomes. GGA RNAi knockdowns in Drosophila have resulted in conflicting data concerning whether the Drosophila GGA (dGGA) is essential. The goal of this study was to define the null phenotype for the unique Drosophila GGA. We describe two independently derived dGGA mutations. Neither allele expresses detectable dGGA protein. Homozygous and hemizygous flies with each allele are viable and fertile. In contrast to a previous report using RNAi knockdown, GGA mutant flies show no evidence of age-dependent retinal degeneration or cathepsin missorting. Our results demonstrate that several of the previous RNAi knockdown phenotypes were the result of off-target effects. However, GGA null flies are hypersensitive to dietary chloroquine and to starvation, implicating GGA in lysosomal function and autophagy.
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Affiliation(s)
- Shan Luan
- Department of Biology, Macelwane Hall, Saint Louis University, St. Louis, Missouri, United States of America
| | - Anne M. Ilvarsonn
- Department of Biology, Macelwane Hall, Saint Louis University, St. Louis, Missouri, United States of America
| | - Joel C. Eissenberg
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis, University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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21
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Sansone CL, Blumenthal EM. Developmental expression of drop-dead is required for early adult survival and normal body mass in Drosophila melanogaster. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 42:690-8. [PMID: 22728457 PMCID: PMC3416960 DOI: 10.1016/j.ibmb.2012.06.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/28/2012] [Accepted: 06/05/2012] [Indexed: 05/07/2023]
Abstract
In Drosophila melanogaster, mutations in the gene drop-dead (drd) result in early adult lethality, with flies dying within 2 weeks of eclosion. Additional phenotypes include neurodegeneration, tracheal defects, starvation, reduced body mass, and female sterility. The cause of early lethality and the function of the drd protein remain unknown. In the current study, the temporal profiles of drd expression required for adult survival and body mass regulation were investigated. Knockdown of drd expression by UAS-RNAi transgenes and rescue of drd expression on a drd mutant background by a UAS-drd transgene were controlled with the Heat Shock Protein 70 (Hsp70)-Gal4 driver. Flies were heat-shocked at different stages of their lifecycle, and the survival and body mass of the resulting adult flies were assayed. Surprisingly, the adult lethal phenotype did not depend upon drd expression in the adult. Rather, expression of drd during the second half of metamorphosis was both necessary and sufficient to prevent rapid adult mortality. In contrast, the attainment of normal adult body mass required a different temporal pattern of drd expression. In this case, manipulation of drd expression solely during larval development or metamorphosis had no effect on body mass, while knockdown or rescue of drd expression during all of pre-adult (embryonic, larval, and pupal) development did significantly alter body mass. Together, these results indicate that the adult-lethal gene drd is required only during development. Furthermore, the mutant phenotypes of body mass and lifespan are separable phenotypes arising from an absence of drd expression at different developmental stages.
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22
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Lopez-Herrera G, Tampella G, Pan-Hammarström Q, Herholz P, Trujillo-Vargas C, Phadwal K, Simon A, Moutschen M, Etzioni A, Mory A, Srugo I, Melamed D, Hultenby K, Liu C, Baronio M, Vitali M, Philippet P, Dideberg V, Aghamohammadi A, Rezaei N, Enright V, Du L, Salzer U, Eibel H, Pfeifer D, Veelken H, Stauss H, Lougaris V, Plebani A, Gertz E, Schäffer A, Hammarström L, Grimbacher B. Deleterious mutations in LRBA are associated with a syndrome of immune deficiency and autoimmunity. Am J Hum Genet 2012; 90:986-1001. [PMID: 22608502 PMCID: PMC3370280 DOI: 10.1016/j.ajhg.2012.04.015] [Citation(s) in RCA: 345] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 03/07/2012] [Accepted: 04/11/2012] [Indexed: 12/14/2022] Open
Abstract
Most autosomal genetic causes of childhood-onset hypogammaglobulinemia are currently not well understood. Most affected individuals are simplex cases, but both autosomal-dominant and autosomal-recessive inheritance have been described. We performed genetic linkage analysis in consanguineous families affected by hypogammaglobulinemia. Four consanguineous families with childhood-onset humoral immune deficiency and features of autoimmunity shared genotype evidence for a linkage interval on chromosome 4q. Sequencing of positional candidate genes revealed that in each family, affected individuals had a distinct homozygous mutation in LRBA (lipopolysaccharide responsive beige-like anchor protein). All LRBA mutations segregated with the disease because homozygous individuals showed hypogammaglobulinemia and autoimmunity, whereas heterozygous individuals were healthy. These mutations were absent in healthy controls. Individuals with homozygous LRBA mutations had no LRBA, had disturbed B cell development, defective in vitro B cell activation, plasmablast formation, and immunoglobulin secretion, and had low proliferative responses. We conclude that mutations in LRBA cause an immune deficiency characterized by defects in B cell activation and autophagy and by susceptibility to apoptosis, all of which are associated with a clinical phenotype of hypogammaglobulinemia and autoimmunity.
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Affiliation(s)
- Gabriela Lopez-Herrera
- Department of Immunology, Division of Infection and Immunity, University College London, Royal Free Hospital, London NW3 2QG, UK
- Immunodeficiency Research Unit, National Institute of Pediatrics, Mexico City 04530, Mexico
| | - Giacomo Tampella
- Pediatrics Clinic and Institute of Molecular Medicine A. Novicelli, University of Brescia, Spedali Civili di Brescia, Brescia 25123, Italy
| | - Qiang Pan-Hammarström
- Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, SE-14186 Stockholm, Sweden
| | - Peer Herholz
- Centre of Chronic Immunodeficiency, University Medical Centre, 79108 Freiburg, Germany
| | - Claudia M. Trujillo-Vargas
- Department of Immunology, Division of Infection and Immunity, University College London, Royal Free Hospital, London NW3 2QG, UK
- Group of Primary Immunodeficiencies, University of Antioquia, Medellin 1226, Colombia
| | - Kanchan Phadwal
- Biomedical Research Centre Translational Immunology Lab, National Institute for Health Research, Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Anna Katharina Simon
- Biomedical Research Centre Translational Immunology Lab, National Institute for Health Research, Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
- Medcial Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
| | - Michel Moutschen
- University of Liège Center of Immunology, Laboratory of Immunoendocrinology, Institute of Pathology, Liège-Sart Tilman 4000, Belgium
| | - Amos Etzioni
- Division of Pediatrics and Immunology, Rappaport School of Medicine, Technion, Haifa 31096, Israel
| | - Adi Mory
- Division of Pediatrics and Immunology, Rappaport School of Medicine, Technion, Haifa 31096, Israel
| | - Izhak Srugo
- Division of Pediatrics and Immunology, Rappaport School of Medicine, Technion, Haifa 31096, Israel
| | - Doron Melamed
- Division of Pediatrics and Immunology, Rappaport School of Medicine, Technion, Haifa 31096, Israel
| | - Kjell Hultenby
- Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, SE-14186 Stockholm, Sweden
| | - Chonghai Liu
- Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, SE-14186 Stockholm, Sweden
- Department of Pediatrics, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan 637000, China
| | - Manuela Baronio
- Pediatrics Clinic and Institute of Molecular Medicine A. Novicelli, University of Brescia, Spedali Civili di Brescia, Brescia 25123, Italy
| | - Massimiliano Vitali
- Pediatrics Clinic and Institute of Molecular Medicine A. Novicelli, University of Brescia, Spedali Civili di Brescia, Brescia 25123, Italy
| | - Pierre Philippet
- Department of Pediatrics, Centre Hospitalier Chrétien-Esperance, Montegnée 4420, Belgium
| | - Vinciane Dideberg
- University of Liège, Center for Human Genetics, Liège-Sart Tilman B-4000, Belgium
| | - Asghar Aghamohammadi
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences. Tehran 14194, Iran
| | - Nima Rezaei
- Molecular Immunology Research Center and Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran 14194, Iran
| | - Victoria Enright
- Department of Immunology, Division of Infection and Immunity, University College London, Royal Free Hospital, London NW3 2QG, UK
| | - Likun Du
- Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, SE-14186 Stockholm, Sweden
| | - Ulrich Salzer
- Centre of Chronic Immunodeficiency, University Medical Centre, 79108 Freiburg, Germany
| | - Hermann Eibel
- Centre of Chronic Immunodeficiency, University Medical Centre, 79108 Freiburg, Germany
| | - Dietmar Pfeifer
- Department of Hematology and Oncology, Freiburg University Medical Center, Freiburg 79106, Germany
| | - Hendrik Veelken
- Department of Hematology, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
| | - Hans Stauss
- Department of Immunology, Division of Infection and Immunity, University College London, Royal Free Hospital, London NW3 2QG, UK
| | - Vassilios Lougaris
- Pediatrics Clinic and Institute of Molecular Medicine A. Novicelli, University of Brescia, Spedali Civili di Brescia, Brescia 25123, Italy
| | - Alessandro Plebani
- Pediatrics Clinic and Institute of Molecular Medicine A. Novicelli, University of Brescia, Spedali Civili di Brescia, Brescia 25123, Italy
| | - E. Michael Gertz
- National Center for Biotechnology Information, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20894, USA
| | - Alejandro A. Schäffer
- National Center for Biotechnology Information, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20894, USA
| | - Lennart Hammarström
- Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, SE-14186 Stockholm, Sweden
| | - Bodo Grimbacher
- Department of Immunology, Division of Infection and Immunity, University College London, Royal Free Hospital, London NW3 2QG, UK
- Centre of Chronic Immunodeficiency, University Medical Centre, 79108 Freiburg, Germany
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23
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Olszewski PK, Rozman J, Jacobsson JA, Rathkolb B, Strömberg S, Hans W, Klockars A, Alsiö J, Risérus U, Becker L, Hölter SM, Elvert R, Ehrhardt N, Gailus-Durner V, Fuchs H, Fredriksson R, Wolf E, Klopstock T, Wurst W, Levine AS, Marcus C, Hrabě de Angelis M, Klingenspor M, Schiöth HB, Kilimann MW. Neurobeachin, a regulator of synaptic protein targeting, is associated with body fat mass and feeding behavior in mice and body-mass index in humans. PLoS Genet 2012; 8:e1002568. [PMID: 22438821 PMCID: PMC3305408 DOI: 10.1371/journal.pgen.1002568] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/16/2012] [Indexed: 01/08/2023] Open
Abstract
Neurobeachin (Nbea) regulates neuronal membrane protein trafficking and is required for the development and functioning of central and neuromuscular synapses. In homozygous knockout (KO) mice, Nbea deficiency causes perinatal death. Here, we report that heterozygous KO mice haploinsufficient for Nbea have higher body weight due to increased adipose tissue mass. In several feeding paradigms, heterozygous KO mice consumed more food than wild-type (WT) controls, and this consumption was primarily driven by calories rather than palatability. Expression analysis of feeding-related genes in the hypothalamus and brainstem with real-time PCR showed differential expression of a subset of neuropeptide or neuropeptide receptor mRNAs between WT and Nbea+/− mice in the sated state and in response to food deprivation, but not to feeding reward. In humans, we identified two intronic NBEA single-nucleotide polymorphisms (SNPs) that are significantly associated with body-mass index (BMI) in adult and juvenile cohorts. Overall, data obtained in mice and humans suggest that variation of Nbea abundance or activity critically affects body weight, presumably by influencing the activity of feeding-related neural circuits. Our study emphasizes the importance of neural mechanisms in body weight control and points out NBEA as a potential risk gene in human obesity. Body weight and energy balance are under very complex neural, endocrine, and metabolic control. Correspondingly, recent research suggests that hundreds of genes contribute to human obesity and that only a small proportion of them have as yet been identified. Neurobeachin (Nbea) is a protein specifically expressed in nerve and endocrine cells and is important for neurotransmission, apparently by influencing the synaptic targeting of membrane proteins. Here, we show that heterozygous knockout mice, expressing Nbea at 50% of normal levels, display increased adipose tissue mass, abnormal feeding behavior, and modified expression of specific genes in the brainstem and hypothalamus known to be important for body weight control. Moreover, we find that NBEA gene polymorphisms are associated with body-mass index in adult and juvenile human cohorts. Our results demonstrate that variation of Nbea activity critically affects body weight, presumably by influencing the activity of feeding-related neural circuits. They emphasize the importance of neural mechanisms in body weight control, and they identify NBEA as a potential genetic risk factor in human obesity.
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Affiliation(s)
- Pawel K. Olszewski
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- Minnesota Obesity Center, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Molecular Nutritional Medicine, Else Kröner-Fresenius Center and ZIEL Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Josefin A. Jacobsson
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, München, Germany
| | - Siv Strömberg
- Molecular Cell Biology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Wolfgang Hans
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Anica Klockars
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Johan Alsiö
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Ulf Risérus
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Lore Becker
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Department of Neurology, Friedrich-Baur-Institut, Ludwig-Maximilians-Universität München, München, Germany
| | - Sabine M. Hölter
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany
| | - Ralf Elvert
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Nicole Ehrhardt
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Valérie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Robert Fredriksson
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Eckhard Wolf
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, München, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institut, Ludwig-Maximilians-Universität München, München, Germany
| | - Wolfgang Wurst
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany
- Max-Planck-Institute for Psychiatry, München, Germany
- Technical University München-Weihenstephan, Lehrstuhl für Entwicklungsgenetik c/o Helmholtz Zentrum München, Neuherberg, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Munich, Germany
| | - Allen S. Levine
- Minnesota Obesity Center, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Claude Marcus
- Department for Clinical Science, Intervention, and Technology, Karolinska Institutet, Division of Pediatrics, National Childhood Obesity Centre, Stockholm, Sweden
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
| | - Martin Klingenspor
- Molecular Nutritional Medicine, Else Kröner-Fresenius Center and ZIEL Research Center for Nutrition and Food Sciences, Technische Universität München, Freising-Weihenstephan, Germany
| | - Helgi B. Schiöth
- Functional Pharmacology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Manfred W. Kilimann
- Molecular Cell Biology Unit, Department of Neuroscience, Uppsala University, Uppsala, Sweden
- * E-mail:
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Eissenberg JC, Ilvarsonn AM, Sly WS, Waheed A, Krzyzanek V, Pohlmann R, Waschkau D, Kretzschmar D, Dennes AC. Drosophila GGA model: an ultimate gateway to GGA analysis. Traffic 2011; 12:1821-38. [PMID: 21923734 PMCID: PMC3601743 DOI: 10.1111/j.1600-0854.2011.01285.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Golgi-localized, γ-ear-containing, ADP ribosylation factor-binding (GGA) proteins are monomeric adaptors implicated in clathrin-mediated vesicular transport between the trans Golgi network and endosomes, characterized mainly from cell culture analysis of lysosomal sorting. To provide the first demonstration of GGA's role in vivo, we used Drosophila which has a single GGA and a single lysosomal sorting receptor, lysosomal enzyme receptor protein (LERP). Using RNAi knockdowns, we show that the Drosophila GGA is required for lysosomal sorting. We further identified authentic components of the Drosophila lysosomal sorting system--the sorting receptor LERP, the sorting adaptor GGA and the lysosomal cargo cathepsins B1, D and L--to show that GGA depletion results in lysosomal dysfunction. Abnormal lysosomal morphology, missorting of lysosomal cathepsins and impaired lysosomal proteolysis show disturbed LERP trafficking after GGA depletion. GGA is highly expressed in the mushroom bodies and the pigment cells of the retina, and increasing or decreasing the levels of GGA in the eyes leads to retinal defects. Reduced GGA levels also enhance an eye defect caused by overexpression of the autophagy-associated protein Blue cheese (Bchs), implicating GGA in autophagic processes. This shows that Drosophila provides an excellent whole-animal model to gain new insights into the function of GGA in the physiological environment of a multicellular organism.
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Affiliation(s)
- Joel C. Eissenberg
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, MO 63104, USA
| | - Anne M. Ilvarsonn
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, MO 63104, USA
| | - William S. Sly
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, MO 63104, USA
| | - Abdul Waheed
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, MO 63104, USA
| | - Vladislav Krzyzanek
- Institute of Medical Physics and Biophysics University of Muenster, 48149 Muenster, Germany
| | - Regina Pohlmann
- UKM, Institute of Physiological Chemistry and Pathobiochemistry, 48149 Münster, Germany
| | - Daniela Waschkau
- UKM, Institute of Physiological Chemistry and Pathobiochemistry, 48149 Münster, Germany
| | | | - André C. Dennes
- UKM, Institute of Physiological Chemistry and Pathobiochemistry, 48149 Münster, Germany
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Gulsuner S, Tekinay AB, Doerschner K, Boyaci H, Bilguvar K, Unal H, Ors A, Onat OE, Atalar E, Basak AN, Topaloglu H, Kansu T, Tan M, Tan U, Gunel M, Ozcelik T. Homozygosity mapping and targeted genomic sequencing reveal the gene responsible for cerebellar hypoplasia and quadrupedal locomotion in a consanguineous kindred. Genome Res 2011; 21:1995-2003. [PMID: 21885617 DOI: 10.1101/gr.126110.111] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The biological basis for the development of the cerebro-cerebellar structures required for posture and gait in humans is poorly understood. We investigated a large consanguineous family from Turkey exhibiting an extremely rare phenotype associated with quadrupedal locomotion, mental retardation, and cerebro-cerebellar hypoplasia, linked to a 7.1-Mb region of homozygosity on chromosome 17p13.1-13.3. Diffusion weighted imaging and fiber tractography of the patients' brains revealed morphological abnormalities in the cerebellum and corpus callosum, in particular atrophy of superior, middle, and inferior peduncles of the cerebellum. Structural magnetic resonance imaging showed additional morphometric abnormalities in several cortical areas, including the corpus callosum, precentral gyrus, and Brodmann areas BA6, BA44, and BA45. Targeted sequencing of the entire homozygous region in three affected individuals and two obligate carriers uncovered a private missense mutation, WDR81 p.P856L, which cosegregated with the condition in the extended family. The mutation lies in a highly conserved region of WDR81, flanked by an N-terminal BEACH domain and C-terminal WD40 beta-propeller domains. WDR81 is predicted to be a transmembrane protein. It is highly expressed in the cerebellum and corpus callosum, in particular in the Purkinje cell layer of the cerebellum. WDR81 represents the third gene, after VLDLR and CA8, implicated in quadrupedal locomotion in humans.
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Affiliation(s)
- Suleyman Gulsuner
- Department of Molecular Biology and Genetics, Faculty of Science, Bilkent University, Ankara 06800, Turkey
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Lysosomal proteolysis inhibition selectively disrupts axonal transport of degradative organelles and causes an Alzheimer's-like axonal dystrophy. J Neurosci 2011; 31:7817-30. [PMID: 21613495 DOI: 10.1523/jneurosci.6412-10.2011] [Citation(s) in RCA: 341] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the hallmark neuritic dystrophy of Alzheimer's disease (AD), autophagic vacuoles containing incompletely digested proteins selectively accumulate in focal axonal swellings, reflecting defects in both axonal transport and autophagy. Here, we investigated the possibility that impaired lysosomal proteolysis could be a basis for both of these defects leading to neuritic dystrophy. In living primary mouse cortical neurons expressing fluorescence-tagged markers, LC3-positive autophagosomes forming in axons rapidly acquired the endo-lysosomal markers Rab7 and LAMP1 and underwent exclusive retrograde movement. Proteolytic clearance of these transported autophagic vacuoles was initiated after fusion with bidirectionally moving lysosomes that increase in number at more proximal axon levels and in the perikaryon. Disrupting lysosomal proteolysis by either inhibiting cathepsins directly or by suppressing lysosomal acidification slowed the axonal transport of autolysosomes, late endosomes, and lysosomes and caused their selective accumulation within dystrophic axonal swellings. Mitochondria and other organelles lacking cathepsins moved normally under these conditions, indicating that the general functioning of the axonal transport system was preserved. Dystrophic swellings induced by lysosomal proteolysis inhibition resembled in composition those in several mouse models of AD and also acquired other AD-like features, including immunopositivity for ubiquitin, amyloid precursor protein, and hyperphosphorylated neurofilament proteins. Restoration of lysosomal proteolysis reversed the affected movements of proteolytic Rab7 vesicles, which in turn essentially cleared autophagic substrates and reversed the axonal dystrophy. These studies identify the AD-associated defects in neuronal lysosomal proteolysis as a possible basis for the selective transport abnormalities and highly characteristic pattern of neuritic dystrophy associated with AD.
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Kriston-Vizi J, Thong NW, Poh CL, Yee KC, Ling JSP, Kraut R, Wasser M. Gebiss: an ImageJ plugin for the specification of ground truth and the performance evaluation of 3D segmentation algorithms. BMC Bioinformatics 2011; 12:232. [PMID: 21668958 PMCID: PMC3225128 DOI: 10.1186/1471-2105-12-232] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 06/13/2011] [Indexed: 02/06/2023] Open
Abstract
Background Image segmentation is a crucial step in quantitative microscopy that helps to define regions of tissues, cells or subcellular compartments. Depending on the degree of user interactions, segmentation methods can be divided into manual, automated or semi-automated approaches. 3D image stacks usually require automated methods due to their large number of optical sections. However, certain applications benefit from manual or semi-automated approaches. Scenarios include the quantification of 3D images with poor signal-to-noise ratios or the generation of so-called ground truth segmentations that are used to evaluate the accuracy of automated segmentation methods. Results We have developed Gebiss; an ImageJ plugin for the interactive segmentation, visualisation and quantification of 3D microscopic image stacks. We integrated a variety of existing plugins for threshold-based segmentation and volume visualisation. Conclusions We demonstrate the application of Gebiss to the segmentation of nuclei in live Drosophila embryos and the quantification of neurodegeneration in Drosophila larval brains. Gebiss was developed as a cross-platform ImageJ plugin and is freely available on the web at http://imaging.bii.a-star.edu.sg/projects/gebiss/.
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Affiliation(s)
- Janos Kriston-Vizi
- Bioinformatics Institute, Agency for Science, Technology and Research (A*STAR), 138671, Singapore.
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28
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Yamada K, Fuwa TJ, Ayukawa T, Tanaka T, Nakamura A, Wilkin MB, Baron M, Matsuno K. Roles of Drosophila Deltex in Notch receptor endocytic trafficking and activation. Genes Cells 2011; 16:261-72. [DOI: 10.1111/j.1365-2443.2011.01488.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Ping Y, Waro G, Licursi A, Smith S, Vo-Ba DA, Tsunoda S. Shal/K(v)4 channels are required for maintaining excitability during repetitive firing and normal locomotion in Drosophila. PLoS One 2011; 6:e16043. [PMID: 21264215 PMCID: PMC3022017 DOI: 10.1371/journal.pone.0016043] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Accepted: 12/03/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Rhythmic behaviors, such as walking and breathing, involve the coordinated activity of central pattern generators in the CNS, sensory feedback from the PNS, to motoneuron output to muscles. Unraveling the intrinsic electrical properties of these cellular components is essential to understanding this coordinated activity. Here, we examine the significance of the transient A-type K(+) current (I(A)), encoded by the highly conserved Shal/K(v)4 gene, in neuronal firing patterns and repetitive behaviors. While I(A) is present in nearly all neurons across species, elimination of I(A) has been complicated in mammals because of multiple genes underlying I(A), and/or electrical remodeling that occurs in response to affecting one gene. METHODOLOGY/PRINCIPAL FINDINGS In Drosophila, the single Shal/K(v)4 gene encodes the predominant I(A) current in many neuronal cell bodies. Using a transgenically expressed dominant-negative subunit (DNK(v)4), we show that I(A) is completely eliminated from cell bodies, with no effect on other currents. Most notably, DNK(v)4 neurons display multiple defects during prolonged stimuli. DNK(v)4 neurons display shortened latency to firing, a lower threshold for repetitive firing, and a progressive decrement in AP amplitude to an adapted state. We record from identified motoneurons and show that Shal/K(v)4 channels are similarly required for maintaining excitability during repetitive firing. We then examine larval crawling, and adult climbing and grooming, all behaviors that rely on repetitive firing. We show that all are defective in the absence of Shal/K(v)4 function. Further, knock-out of Shal/K(v)4 function specifically in motoneurons significantly affects the locomotion behaviors tested. CONCLUSIONS/SIGNIFICANCE Based on our results, Shal/K(v)4 channels regulate the initiation of firing, enable neurons to continuously fire throughout a prolonged stimulus, and also influence firing frequency. This study shows that Shal/K(v)4 channels play a key role in repetitively firing neurons during prolonged input/output, and suggests that their function and regulation are important for rhythmic behaviors.
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Affiliation(s)
- Yong Ping
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Girma Waro
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ashley Licursi
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Sarah Smith
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Dai-An Vo-Ba
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Susan Tsunoda
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
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Trantow CM, Hedberg-Buenz A, Iwashita S, Moore SA, Anderson MG. Elevated oxidative membrane damage associated with genetic modifiers of Lyst-mutant phenotypes. PLoS Genet 2010; 6:e1001008. [PMID: 20617205 PMCID: PMC2895641 DOI: 10.1371/journal.pgen.1001008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 05/27/2010] [Indexed: 01/16/2023] Open
Abstract
LYST is a large cytosolic protein that influences the biogenesis of lysosome-related organelles, and mutation of the encoding gene, LYST, can cause Chediak-Higashi syndrome. Recently, Lyst-mutant mice were recognized to also exhibit an iris disease resembling exfoliation syndrome, a common cause of glaucoma in humans. Here, Lyst-mutant iris phenotypes were used in a search for genes that influence Lyst pathways. In a candidate gene–driven approach, albino Lyst-mutant mice homozygous for a mutation in Tyr, whose product is key to melanin synthesis within melanosomes, exhibited complete rescue of Lyst-mutant iris phenotypes. In a genetic background–driven approach using a DBA/2J strain of congenic mice, an interval containing Tyrp1 enhanced Lyst-dependent iris phenotypes. Thus, both experimental approaches implicated the melanosome, an organelle that is a potential source of oxidative stress, as contributing to the disease phenotype. Confirming an association with oxidative damage, Lyst mutation resulted in genetic context–sensitive changes in iris lipid hydroperoxide levels, being lowest in albino and highest in DBA/2J mice. Surprisingly, the DBA/2J genetic background also exposed a late-onset neurodegenerative phenotype involving cerebellar Purkinje-cell degeneration. These results identify an association between oxidative damage to lipid membranes and the severity of Lyst-mutant phenotypes, revealing a new mechanism that contributes to pathophysiology involving LYST. LYST is a poorly understood protein involved in hereditary disease. Mutations in the encoding gene cause Chediak-Higashi syndrome, a rare lethal disease affecting multiple tissues of the body. Mutations in Lyst also recapitulate features of exfoliation syndrome, a common disease affecting the anterior chamber of the eye. Unfortunately, the Lyst gene is quite large, rendering it difficult to study by many molecular and cellular approaches. Here, we use a genetic approach in mice to identify additional genetic pathways which might modify, or prevent, the ill consequences associated with Lyst mutation. Our experiments demonstrate that Lyst mutation results in elevated levels of oxidative damage to lipid membranes. These results identify a previously unrecognized consequence of Lyst mutation and a modifiable pathway of potential clinical relevance in humans. Ultimately, knowledge of these events will contribute to the design of new therapeutic strategies allowing a similar alleviation of disease in humans.
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Affiliation(s)
- Colleen M. Trantow
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, Iowa, United States of America
| | - Adam Hedberg-Buenz
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, Iowa, United States of America
| | - Sachiyo Iwashita
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, Iowa, United States of America
| | - Steven A. Moore
- Department of Pathology, The University of Iowa, Iowa City, Iowa, United States of America
| | - Michael G. Anderson
- Department of Molecular Physiology and Biophysics, The University of Iowa, Iowa City, Iowa, United States of America
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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31
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Hortsch R, Lee E, Erathodiyil N, Hebbar S, Steinert S, Lee JY, Chua DSK, Kraut R. Glycolipid trafficking in Drosophila undergoes pathway switching in response to aberrant cholesterol levels. Mol Biol Cell 2010; 21:778-90. [PMID: 20053687 PMCID: PMC2828964 DOI: 10.1091/mbc.e09-01-0005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 11/24/2009] [Accepted: 12/22/2009] [Indexed: 01/29/2023] Open
Abstract
In lipid storage diseases, the intracellular trafficking of sphingolipids is altered by conditions of aberrant cholesterol accumulation. Drosophila has been used recently to model lipid storage diseases, but the effects of sterol accumulation on sphingolipid trafficking are not known in the fly, and the trafficking of sphingolipids in general has not been studied in this model organism. Here, we examined the uptake and intracellular distribution of a fluorescent glycolipid analog, BODIPY-lactosyl-ceramide, in Drosophila neurons. The uptake mechanism and intracellular trafficking route of this simple glycolipid are largely conserved. Our principle finding is that cholesterol steers trafficking of the glycolipid between Golgi, lysosome, and recycling compartments. Our analyses support the idea that cholesterol storage in Drosophila triggers a switch in glycolipid trafficking from the biosynthetic to the degradative endolysosomal pathway, whereas cholesterol depletion eliminates recycling of the glycolipid. Unexpectedly, we observe a novel phenomenon we term "hijacking," whereby lactosyl-ceramide diverts the trafficking pathway of an endocytic cargo, dextran, completely away from its lysosomal target. This work establishes that glycolipid trafficking in Drosophila undergoes changes similar to those seen in mammalian cells under conditions of cholesterol storage and therefore validates Drosophila as a suitable model organism in which to study lipid storage diseases.
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Affiliation(s)
- Ralf Hortsch
- Institute of Bioengineering and Nanotechnology, Agency for Science, Technology, and Research, Singapore 138669; and
| | - Esther Lee
- Institute of Bioengineering and Nanotechnology, Agency for Science, Technology, and Research, Singapore 138669; and
| | - Nandanan Erathodiyil
- Institute of Bioengineering and Nanotechnology, Agency for Science, Technology, and Research, Singapore 138669; and
| | - Sarita Hebbar
- Institute of Bioengineering and Nanotechnology, Agency for Science, Technology, and Research, Singapore 138669; and
| | - Steffen Steinert
- Institute of Bioengineering and Nanotechnology, Agency for Science, Technology, and Research, Singapore 138669; and
| | - Jun Yu Lee
- School of Biological Sciences, Nanyang Technological University, Singapore 639798
| | - Doreen See Kin Chua
- School of Biological Sciences, Nanyang Technological University, Singapore 639798
| | - Rachel Kraut
- School of Biological Sciences, Nanyang Technological University, Singapore 639798
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Rancillac A, Lainé J, Perrenoud Q, Geoffroy H, Ferezou I, Vitalis T, Rossier J. Degenerative abnormalities in transgenic neocortical neuropeptide Y interneurons expressing tau-green fluorescent protein. J Neurosci Res 2010; 88:487-99. [PMID: 19830842 DOI: 10.1002/jnr.22234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The introduction of a reporter gene into bacterial artificial chromosome (BAC) constructs allows a rapid identification of the cell type expressing the gene of interest. Here we used BAC transgenic mice expressing a tau-sapphire green fluorescent protein (GFP) under the transcriptional control of the neuropeptide Y (NPY) genomic sequence to characterize morphological and electrophysiological properties of NPY-GFP interneurons of the mouse juvenile primary somatosensory cortex. Electrophysiological whole-cell recordings and biocytin injections were performed to allow the morphological reconstruction of the recorded neurons in three dimensions. Ninety-six recorded NPY-GFP interneurons were compared with 39 wild-type (WT) NPY interneurons, from which 23 and 19 were reconstructed, respectively. We observed that 91% of the reconstructed NPY-GFP interneurons had developed an atypical axonal swelling from which emerge numerous ramifications. These abnormalities were very heterogeneous in shape and size. They were immunoreactive for the microtubule-associated protein tau and the lysosomal-associated membrane protein 1 (LAMP1). Moreover, an electron microscopic analysis revealed the accumulation of numerous autophagic and lysosomal vacuoles in swollen axons. Morphological analyses of NPY-GFP interneurons also indicated that their somata were smaller, their entire dendritic tree was thickened and presented a restricted spatial distribution in comparison with WT NPY interneurons. Finally, the morphological defects observed in NPY-GFP interneurons appeared to be associated with alterations of their electrophysiological intrinsic properties. Altogether, these results demonstrate that NPY-GFP interneurons developed dystrophic axonal swellings and severe morphological and electrophysiological defects that could be due to the overexpression of tau-coupled reporter constructs.
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Affiliation(s)
- Armelle Rancillac
- Laboratoire de Neurobiologie, CNRS UMR 7637, ESPCI ParisTech, Paris, France
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Zheng J, Yan T, Feng Y, Zhai Q. Involvement of lysosomes in the early stages of axon degeneration. Neurochem Int 2009; 56:516-21. [PMID: 20036294 DOI: 10.1016/j.neuint.2009.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 12/15/2009] [Accepted: 12/17/2009] [Indexed: 01/08/2023]
Abstract
Axon degeneration is a common hallmark of many neurodegenerative diseases, and the underlying mechanism remains largely unknown. Lysosomes are involved in some neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Whether lysosomes are involved in axon degeneration is yet to be elucidated. In this study, we found only about 10% lysosomes remained in axons of cultured superior cervical ganglia (SCGs) after transection for 4h when stained with LysoTracker. Furthermore, we found that lysosomal disruption occurred earlier than morphological changes and loss of mitochondrial membrane potential. In addition, the well-known axon-protective protein Wld(S) delayed injury-induced axon degeneration from both morphological changes and lysosomal disruption. Lysosomal inhibitors including chloroquine and ammonium chloride induced axon degeneration in cultured SCGs, and Wld(S) also slowed down the axon degeneration induced by lysosomal inhibitors. All these data suggest that lysosomal disruption is an early marker of axon degeneration, and inhibition of lysosome induces axon degeneration in a Wld(S)-protectable way. Thus, maintenance of normal lysosomal function might be an important approach to delay axon degeneration in neurodegenerative diseases.
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Affiliation(s)
- Jin Zheng
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Medrihan L, Rohlmann A, Fairless R, Andrae J, Döring M, Missler M, Zhang W, Kilimann MW. Neurobeachin, a protein implicated in membrane protein traffic and autism, is required for the formation and functioning of central synapses. J Physiol 2009; 587:5095-106. [PMID: 19723784 DOI: 10.1113/jphysiol.2009.178236] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The development of neuronal networks in the brain requires the differentiation of functional synapses. Neurobeachin (Nbea) was identified as a putative regulator of membrane protein trafficking associated with tubulovesicular endomembranes and postsynaptic plasma membranes. Nbea is essential for evoked transmission at neuromuscular junctions, but its role in the central nervous system has not been characterized. Here, we have studied central synapses of a newly generated gene-trap knockout (KO) mouse line at embryonic day 18, because null-mutant mice are paralysed and die perinatally. Although the overall brain architecture was normal, we identified major abnormalities of synaptic function in mutant animals. In acute slices from the brainstem, both spontaneous excitatory and inhibitory postsynaptic currents were clearly reduced and failure rates of evoked inhibitory responses were markedly increased. In addition, the frequency of miniature excitatory and both the frequency and amplitudes of miniature inhibitory postsynaptic currents were severely diminished in KO mice, indicating a perturbation of both action potential-dependent and -independent transmitter release. Moreover, Nbea appears to be important for the formation and composition of central synapses because the area density of mature asymmetric contacts in the fetal brainstem was reduced to 30% of wild-type levels, and the expression levels of a subset of synaptic marker proteins were smaller than in littermate controls. Our data demonstrate for the first time a function of Nbea at central synapses that may be based on its presumed role in targeting membrane proteins to synaptic contacts, and are consistent with the 'excitatory-inhibitory imbalance' model of autism where Nbea gene rearrangements have been detected in some patients.
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Affiliation(s)
- Lucian Medrihan
- Center for Physiology, Georg-August University and DFG-Research Center of Molecular Physiology of the Brain, D-37073 Göttingen, Germany
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Dell'Angelica EC. AP-3-dependent trafficking and disease: the first decade. Curr Opin Cell Biol 2009; 21:552-9. [PMID: 19497727 DOI: 10.1016/j.ceb.2009.04.014] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 04/28/2009] [Accepted: 04/30/2009] [Indexed: 10/20/2022]
Abstract
The adaptor protein (AP)-3 complex defines a pathway for the intracellular trafficking of membrane-associated proteins in most eukaryotic cells. Ten years ago, genetic defects in AP-3 were linked to a human Mendelian disease, named Hermansky-Pudlak syndrome, characterized by abnormal biogenesis and function of lysosome-related organelles such as melanosomes and platelet dense granules. During recent years, research on this trafficking pathway has significantly expanded its horizons to include evolutionarily divergent eukaryotic models and to embrace functional genomics and proteomics approaches. These studies have brought into focus ideas about the specific roles of this pathway in protein trafficking and organelle biogenesis within the endosomal-lysosomal system.
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Affiliation(s)
- Esteban C Dell'Angelica
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-7088, USA.
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Bakota L, Brandt R. Chapter 2 Live‐Cell Imaging in the Study of Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:49-103. [DOI: 10.1016/s1937-6448(09)76002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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