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Monsalvo-Maraver LA, Ovalle-Noguez EA, Nava-Osorio J, Maya-López M, Rangel-López E, Túnez I, Tinkov AA, Tizabi Y, Aschner M, Santamaría A. Interactions Between the Ubiquitin-Proteasome System, Nrf2, and the Cannabinoidome as Protective Strategies to Combat Neurodegeneration: Review on Experimental Evidence. Neurotox Res 2024; 42:18. [PMID: 38393521 PMCID: PMC10891226 DOI: 10.1007/s12640-024-00694-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/13/2024] [Accepted: 02/04/2024] [Indexed: 02/25/2024]
Abstract
Neurodegenerative disorders are chronic brain diseases that affect humans worldwide. Although many different factors are thought to be involved in the pathogenesis of these disorders, alterations in several key elements such as the ubiquitin-proteasome system (UPS), the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, and the endocannabinoid system (ECS or endocannabinoidome) have been implicated in their etiology. Impairment of these elements has been linked to the origin and progression of neurodegenerative disorders, while their potentiation is thought to promote neuronal survival and overall neuroprotection, as proved with several experimental models. These key neuroprotective pathways can interact and indirectly activate each other. In this review, we summarize the neuroprotective potential of the UPS, ECS, and Nrf2 signaling, both separately and combined, pinpointing their role as a potential therapeutic approach against several hallmarks of neurodegeneration.
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Affiliation(s)
- Luis Angel Monsalvo-Maraver
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.U. Coyoacán, 04510, Mexico City, Mexico.
| | - Enid A Ovalle-Noguez
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.U. Coyoacán, 04510, Mexico City, Mexico
| | - Jade Nava-Osorio
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.U. Coyoacán, 04510, Mexico City, Mexico
| | - Marisol Maya-López
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.U. Coyoacán, 04510, Mexico City, Mexico
- Doctorado en Ciencias Biológicas y de La Salud, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, Mexico
| | - Edgar Rangel-López
- Instituto Nacional de Neurología y Neurocirugía, S.S.A., Mexico City, Mexico
| | - Isaac Túnez
- Instituto de Investigaciones Biomédicas Maimonides de Córdoba (IMIBIC), Departamento de Bioquímica y Biología Molecular, Facultad de Medicina y Enfermería, Universidad de Córdoba, Red Española de Excelencia en Estimulación Cerebral (REDESTIM), Córdoba, Spain
| | - Alexey A Tinkov
- IM Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
- Yaroslavl State University, Yaroslavl, Russia
| | - Yousef Tizabi
- Department of Pharmacology, Howard University College of Medicine, Washington, DC, USA
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Abel Santamaría
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, C.U. Coyoacán, 04510, Mexico City, Mexico.
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2
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AlAbdi L, Desbois M, Rusnac DV, Sulaiman RA, Rosenfeld JA, Lalani S, Murdock DR, Burrage LC, Billie Au PY, Towner S, Wilson WG, Wong L, Brunet T, Strobl-Wildemann G, Burton JE, Hoganson G, McWalter K, Begtrup A, Zarate YA, Christensen EL, Opperman KJ, Giles AC, Helaby R, Kania A, Zheng N, Grill B, Alkuraya FS. Loss-of-function variants in MYCBP2 cause neurobehavioural phenotypes and corpus callosum defects. Brain 2023; 146:1373-1387. [PMID: 36200388 PMCID: PMC10319777 DOI: 10.1093/brain/awac364] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 08/11/2022] [Accepted: 08/22/2022] [Indexed: 11/14/2022] Open
Abstract
The corpus callosum is a bundle of axon fibres that connects the two hemispheres of the brain. Neurodevelopmental disorders that feature dysgenesis of the corpus callosum as a core phenotype offer a valuable window into pathology derived from abnormal axon development. Here, we describe a cohort of eight patients with a neurodevelopmental disorder characterized by a range of deficits including corpus callosum abnormalities, developmental delay, intellectual disability, epilepsy and autistic features. Each patient harboured a distinct de novo variant in MYCBP2, a gene encoding an atypical really interesting new gene (RING) ubiquitin ligase and signalling hub with evolutionarily conserved functions in axon development. We used CRISPR/Cas9 gene editing to introduce disease-associated variants into conserved residues in the Caenorhabditis elegans MYCBP2 orthologue, RPM-1, and evaluated functional outcomes in vivo. Consistent with variable phenotypes in patients with MYCBP2 variants, C. elegans carrying the corresponding human mutations in rpm-1 displayed axonal and behavioural abnormalities including altered habituation. Furthermore, abnormal axonal accumulation of the autophagy marker LGG-1/LC3 occurred in variants that affect RPM-1 ubiquitin ligase activity. Functional genetic outcomes from anatomical, cell biological and behavioural readouts indicate that MYCBP2 variants are likely to result in loss of function. Collectively, our results from multiple human patients and CRISPR gene editing with an in vivo animal model support a direct link between MYCBP2 and a human neurodevelopmental spectrum disorder that we term, MYCBP2-related developmental delay with corpus callosum defects (MDCD).
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Affiliation(s)
- Lama AlAbdi
- Department of Zoology, College of Science, King Saud University, Riyadh 11362, Saudi Arabia
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Muriel Desbois
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Domniţa-Valeria Rusnac
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA
- Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Raashda A Sulaiman
- Department of Medical Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Seema Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - David R Murdock
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Ping Yee Billie Au
- Department of Medical Genetics, Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Shelley Towner
- Pediatric Genetics, University of Virginia, Charlottesville, VA 22903, USA
| | - William G Wilson
- Pediatric Genetics, University of Virginia, Charlottesville, VA 22903, USA
| | - Lawrence Wong
- Department of Genetics, Northern California Kaiser Permanente, Oakland, CA 94611, USA
| | - Theresa Brunet
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, 81675 Munich, Germany
- Institute of Neurogenomics (ING), Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | | | - Jennifer E Burton
- Department of Genetics, University of Illinois College of Medicine at Peoria, Peoria, IL 61605, USA
| | - George Hoganson
- Department of Genetics, University of Illinois College of Medicine at Peoria, Peoria, IL 61605, USA
| | - Kirsty McWalter
- Genedx, Inc., 207 Perry Parkway, Gaithersburg, MD 20877, USA
| | - Amber Begtrup
- Genedx, Inc., 207 Perry Parkway, Gaithersburg, MD 20877, USA
| | - Yuri A Zarate
- Section of Genetics and Metabolism, Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA
| | - Elyse L Christensen
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Karla J Opperman
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
| | - Andrew C Giles
- Division of Medical Sciences, University of Northern British Columbia, Prince George, BC V2N 4Z9, Canada
| | - Rana Helaby
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
| | - Artur Kania
- Institut de recherches cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
- Integrated Program in Neuroscience, McGill University, Montréal, QC H3A 2B4, Canada
- Division of Experimental Medicine, McGill University, Montréal, QC H3A 2B2, Canada
- Department of Anatomy and Cell Biology, McGill University, Montréal, QC H3A 0C7, Canada
| | - Ning Zheng
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA
- Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | - Brock Grill
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98101, USA
- Department of Pharmacology, University of Washington School of Medicine, Seattle, WA 98195, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98101, USA
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 11564, Saudi Arabia
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3
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Li W, Gao M, Hu C, Chen X, Zhou Y. NMNAT2: An important metabolic enzyme affecting the disease progression. Biomed Pharmacother 2023; 158:114143. [PMID: 36528916 DOI: 10.1016/j.biopha.2022.114143] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/13/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) is an evolutionarily conserved nicotinamide adenine dinucleotide (NAD+) synthase located in the cytoplasm and Golgi apparatus. NMNAT2 has an important role in neurodegenerative diseases, malignant tumors, and other diseases that seriously endanger human health. NMNAT2 exerts a neuroprotective function through its NAD synthase activity and chaperone function. Among them, the NMNAT2-NAD+-Sterile alpha and Toll/interleukin-1 receptor motif-containing 1 (SARM1) axis is closely related to Wallerian degeneration. Physical injury or pathological stimulation will cause a decrease in NMNAT2, which activates SARM1, leading to axonal degeneration and the occurrence of amyotrophic lateral sclerosis (ALS), Alzheimer's disease, peripheral neuropathy, and other neurodegenerative diseases. In addition, NMNAT2 exerts a cancer-promoting role in solid tumors, including colorectal cancer, lung cancer, ovarian cancer, and glioma, and is closely related to tumor occurrence and development. This paper reviews the chromosomal and subcellular localization of NMNAT2 and its basic biological functions. We also summarize the NMNAT2-related signal transduction pathway and the role of NMNAT2 in diseases. We aimed to provide a new perspective to comprehensively understand the relationship between NMNAT2 and its associated diseases.
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Affiliation(s)
- Wentao Li
- NHC Key Laboratory of Carcinogenesis, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China; Cancer Research Institute, Basic School of Medicine, Central South University, Changsha, Hunan 410078, China
| | - Mengxiang Gao
- NHC Key Laboratory of Carcinogenesis, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China; Cancer Research Institute, Basic School of Medicine, Central South University, Changsha, Hunan 410078, China
| | - Chunhui Hu
- Teaching and Research Section of Clinical Nursing, Xiangya Hospital of Central South University, Changsha, Hunan 410013, China
| | - Xiuwen Chen
- Teaching and Research Section of Clinical Nursing, Xiangya Hospital of Central South University, Changsha, Hunan 410013, China.
| | - Yanhong Zhou
- NHC Key Laboratory of Carcinogenesis, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, China; Cancer Research Institute, Basic School of Medicine, Central South University, Changsha, Hunan 410078, China.
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4
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Lin S. The making of the Drosophila mushroom body. Front Physiol 2023; 14:1091248. [PMID: 36711013 PMCID: PMC9880076 DOI: 10.3389/fphys.2023.1091248] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 01/02/2023] [Indexed: 01/14/2023] Open
Abstract
The mushroom body (MB) is a computational center in the Drosophila brain. The intricate neural circuits of the mushroom body enable it to store associative memories and process sensory and internal state information. The mushroom body is composed of diverse types of neurons that are precisely assembled during development. Tremendous efforts have been made to unravel the molecular and cellular mechanisms that build the mushroom body. However, we are still at the beginning of this challenging quest, with many key aspects of mushroom body assembly remaining unexplored. In this review, I provide an in-depth overview of our current understanding of mushroom body development and pertinent knowledge gaps.
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5
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Pinto MJ, Tomé D, Almeida RD. The Ubiquitinated Axon: Local Control of Axon Development and Function by Ubiquitin. J Neurosci 2021; 41:2796-2813. [PMID: 33789876 PMCID: PMC8018891 DOI: 10.1523/jneurosci.2251-20.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 01/15/2021] [Accepted: 01/22/2021] [Indexed: 02/01/2023] Open
Abstract
Ubiquitin tagging sets protein fate. With a wide range of possible patterns and reversibility, ubiquitination can assume many shapes to meet specific demands of a particular cell across time and space. In neurons, unique cells with functionally distinct axons and dendrites harboring dynamic synapses, the ubiquitin code is exploited at the height of its power. Indeed, wide expression of ubiquitination and proteasome machinery at synapses, a diverse brain ubiquitome, and the existence of ubiquitin-related neurodevelopmental diseases support a fundamental role of ubiquitin signaling in the developing and mature brain. While special attention has been given to dendritic ubiquitin-dependent control, how axonal biology is governed by this small but versatile molecule has been considerably less discussed. Herein, we set out to explore the ubiquitin-mediated spatiotemporal control of an axon's lifetime: from its differentiation and growth through presynaptic formation, function, and pruning.
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Affiliation(s)
- Maria J Pinto
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
| | - Diogo Tomé
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
- Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, 3810-193, Portugal
| | - Ramiro D Almeida
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, 3004-504, Portugal
- Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, 3810-193, Portugal
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6
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Yang M, Guo Y, Wang S, Chen C, Chang YH, Ho MSC. The F-Box Protein CG5003 Regulates Axon Pruning and the Integrity of the Drosophila Mushroom Body. Front Mol Neurosci 2021; 14:634784. [PMID: 33716667 PMCID: PMC7947810 DOI: 10.3389/fnmol.2021.634784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 01/27/2021] [Indexed: 11/25/2022] Open
Abstract
Protein homeostasis serves as an important step in regulating diverse cellular processes underlying the function and development of the nervous system. In particular, the ubiquitination proteasome system (UPS), a universal pathway mediating protein degradation, contributes to the development of numerous synaptic structures, including the Drosophila olfactory-associative learning center mushroom body (MB), thereby affecting associated function. Here, we describe the function of a newly characterized Drosophila F-box protein CG5003, an adaptor for the RING-domain type E3 ligase (SCF complex), in MB development. Lacking CG5003 ubiquitously causes MB γ axon pruning defects and selective CG5003 expression in pan-neurons leads to both γ axon and α/β lobe abnormalities. Interestingly, change in CG5003 expression in MB neurons does not cause any abnormalities in axons, suggesting that CG5003 functions in cells extrinsic to MB to regulate its development. Mass spectrum analysis indicates that silencing CG5003 expression in all neurons affects expression levels of proteins in the cell and structural morphogenesis, transcription regulator activity, and catalytic activity. Our findings reinforce the importance of UPS and identify a new factor in regulating neuronal development as exemplified by the synaptic structure MB.
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Affiliation(s)
- Mengying Yang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yige Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Shuran Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Changyan Chen
- Institute of Intervention Vessel, Shanghai Tenth People's Hospital, Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Tongji University, Shanghai, China
| | - Yung-Heng Chang
- Department of Anesthesiology, Stony Brook School of Medicine, New York, NY, United States
| | - Margaret Su-Chun Ho
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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7
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Lee B, Cho Y. Experimental Model Systems for Understanding Human Axonal Injury Responses. Int J Mol Sci 2021; 22:E474. [PMID: 33418850 PMCID: PMC7824864 DOI: 10.3390/ijms22020474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/03/2020] [Accepted: 12/30/2020] [Indexed: 12/26/2022] Open
Abstract
Neurons are structurally unique and have dendrites and axons that are vulnerable to injury. Some neurons in the peripheral nervous system (PNS) can regenerate their axons after injuries. However, most neurons in the central nervous system (CNS) fail to do so, resulting in irreversible neurological disorders. To understand the mechanisms of axon regeneration, various experimental models have been utilized in vivo and in vitro. Here, we collate the key experimental models that revealed the important mechanisms regulating axon regeneration and degeneration in different systems. We also discuss the advantages of experimenting with the rodent model, considering the application of these findings in understanding human diseases and for developing therapeutic methods.
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Affiliation(s)
| | - Yongcheol Cho
- Laboratory of Axon Regeneration & Degeneration, Department of Life Sciences, Korea University, Anam-ro 145, Seongbuk-gu, Seoul 02841, Korea;
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8
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Russo A, DiAntonio A. Wnd/DLK Is a Critical Target of FMRP Responsible for Neurodevelopmental and Behavior Defects in the Drosophila Model of Fragile X Syndrome. Cell Rep 2020; 28:2581-2593.e5. [PMID: 31484070 PMCID: PMC6746345 DOI: 10.1016/j.celrep.2019.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 07/02/2019] [Accepted: 07/30/2019] [Indexed: 01/23/2023] Open
Abstract
Fragile X syndrome (FXS) is the leading heritable cause of intellectual disability and commonly co-occurs with autism spectrum disorder. Silencing of the Fmr1 gene leads to the absence of the protein product, fragile X mental retardation protein (FMRP), which represses translation of many target mRNAs. Excess translation of these targets is one cause of neuronal dysfunction in FXS. Utilizing the Drosophila model of FXS, we identified the mitogen-activated protein kinase kinase kinase (MAP3K) Wallenda/dual leucine zipper kinase (DLK) as a critical target of FMRP. dFMRP binds Wallenda mRNA and is required to limit Wallenda protein levels. In dFmr1 mutants, Wallenda signaling drives defects in synaptic development, neuronal morphology, and behavior. Pharmacological inhibition of Wallenda in larvae suppresses dFmr1 neurodevelopmental phenotypes, while adult administration prevents dFmr1 behavioral defects. We propose that in dFmr1 mutants chronic Wallenda/DLK signaling disrupts nervous system development and function and that inhibition of this kinase cascade might be a candidate therapeutic intervention for the treatment of FXS. Russo and DiAntonio identify a dysregulated MAPK signaling pathway in the fly model of fragile X syndrome. MAP3K Wnd/DLK drives dFmr1 mutant phenotypes, and pharmacological inhibition of Wnd/DLK prevents neural dysfunction in this model, thus highlighting a possible role for Wnd/DLK in the pathophysiology of fragile X syndrome.
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Affiliation(s)
- Alexandra Russo
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA; Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine in St. Louis, St. Louis, MO 63110, USA.
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9
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Kang H, Zhao J, Jiang X, Li G, Huang W, Cheng H, Duan R. Drosophila Netrin-B controls mushroom body axon extension and regulates courtship-associated learning and memory of a Drosophila fragile X syndrome model. Mol Brain 2019; 12:52. [PMID: 31138234 PMCID: PMC6540430 DOI: 10.1186/s13041-019-0472-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 05/06/2019] [Indexed: 01/29/2023] Open
Abstract
Mushroom body (MB) is a prominent structure essential for olfactory learning and memory in the Drosophila brain. The development of the MB involves the appropriate guidance of axon lobes and sister axon branches. Appropriate guidance that accurately shapes MB development requires the integration of various guidance cues provided by a series of cell types, which guide axons to reach their final positions within the MB neuropils. Netrins are axonal guidance molecules that are conserved regulators of embryonic nerve cord patterning. However, whether they contribute to MB morphogenesis has not yet been evaluated. Here, we find that Netrin-B (NetB) is highly expressed in the MB lobes, regulating lobe length through genetic interactions with the receptors Frazzled and Uncoordinated-5 from 24 h after pupal formation onwards. We observe that overexpression of NetB causes severe β lobe fusion in the MB, which is similar to the MB defects seen in the Drosophila model of fragile X syndrome (FXS). Our results further show that fragile-X mental retardation protein FMRP inhibits the translational activity of human ortholog Netrin-1 (NTN1). Knock-down of NetB significantly rescues the MB defects and ameliorates deficits in the learning and memory in FXS model Drosophila. These results indicate a critical role for NetB in MB lobe extension and identify NetB as a novel target of FMRP which contributes to learning and memory.
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Affiliation(s)
- Huaixing Kang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Juan Zhao
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Xuan Jiang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Guangxu Li
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Wen Huang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Huili Cheng
- Changchun Children' Hospital, Changchun, 130000, Jilin, China.
| | - Ranhui Duan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Medical Genetics, Central South University, Changsha, 410078, Hunan, China. .,Hunan Key Laboratory of Animal Models for Human Diseases, Central South University, Changsha, 410078, Hunan, China.
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10
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Bremer J, Marsden KC, Miller A, Granato M. The ubiquitin ligase PHR promotes directional regrowth of spinal zebrafish axons. Commun Biol 2019; 2:195. [PMID: 31149640 PMCID: PMC6531543 DOI: 10.1038/s42003-019-0434-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/16/2019] [Indexed: 01/05/2023] Open
Abstract
To reconnect with their synaptic targets, severed axons need to regrow robustly and directionally along the pre-lesional trajectory. While mechanisms directing axonal regrowth are poorly understood, several proteins direct developmental axon outgrowth, including the ubiquitin ligase PHR (Mycbp2). Invertebrate PHR also limits regrowth of injured axons, whereas its role in vertebrate axonal regrowth remains elusive. Here we took advantage of the high regrowth capacity of spinal zebrafish axons and observed robust and directional regrowth following laser transection of spinal Mauthner axons. We found that PHR directs regrowing axons along the pre-lesional trajectory and across the transection site. At the transection site, initial regrowth of wild-type axons was multidirectional. Over time, misdirected sprouts were corrected in a PHR-dependent manner. Ablation of cyfip2, known to promote F-actin-polymerization and pharmacological inhibition of JNK reduced misdirected regrowth of PHR-deficient axons, suggesting that PHR controls directional Mauthner axonal regrowth through cyfip2- and JNK-dependent pathways.
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Affiliation(s)
- Juliane Bremer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
| | - Kurt C. Marsden
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
- Present Address: Department of Biological Sciences, North Carolina State University, Raleigh, 27607 NC USA
| | - Adam Miller
- Institute of Neuroscience, University of Oregon, Eugene, 97405 OR USA
| | - Michael Granato
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA USA
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11
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Hamid R, Hajirnis N, Kushwaha S, Saleem S, Kumar V, Mishra RK. Drosophila Choline transporter non-canonically regulates pupal eclosion and NMJ integrity through a neuronal subset of mushroom body. Dev Biol 2019; 446:80-93. [DOI: 10.1016/j.ydbio.2018.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/25/2018] [Accepted: 12/07/2018] [Indexed: 12/19/2022]
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12
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Mecklenburg KL, Weghorst FP, Freed SA, O'Tousa JE. Discordant Responses to MAPK Pathway Stimulation Include Axonal Growths in Adult Drosophila Photoreceptors. Front Mol Neurosci 2018; 11:441. [PMID: 30564098 PMCID: PMC6288290 DOI: 10.3389/fnmol.2018.00441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 11/14/2018] [Indexed: 11/22/2022] Open
Abstract
Wallenda (WND) is the Drosophila member of a conserved family of dual leucine-zipper kinases (DLK) active in both neuronal regeneration and degeneration. We examined the role of WND over-expression on sensory neuron morphology by driving WND in multiple subtypes of Drosophila photoreceptors. WND overexpression under control of the pan-retinal GAL4 driver GMR causes multiple photoreceptor defects including cell death, rhabdomere degeneration, and axonal sprouting. Individual photoreceptor subtypes were assayed using GAL4 drivers specific for each photoreceptor class. Many R7 and R8 cells exhibit axonal sprouting while some show cell degeneration. Delaying the onset of WND overexpression until 20 days of age showed that older adult R7 cells retain the ability to initiate new axon growth. R1–6 photoreceptor cells degenerate in response to WND expression and exhibit rhodopsin loss and rhabdomere degeneration. RNAi knockdown of the MAPK signaling components Kayak (KAY) and Hemipterous (HEP) attenuates the WND-induced loss of Rh1 rhodopsin. UAS-induced HEP expression is similar to WND expression, causing degeneration in R1–6 photoreceptors and axonal sprouting in R7 photoreceptors. These results demonstrate that WND in adult Drosophila photoreceptor cells acts through MAPK signaling activity with both regenerative and degenerative responses. These photoreceptors provide a tractable experimental model to reveal cellular mechanisms driving contradictory WND signaling responses.
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Affiliation(s)
- Kirk L Mecklenburg
- Department of Biology, Indiana University South Bend, South Bend, IN, United States
| | - Forrest P Weghorst
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Stephanie A Freed
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
| | - Joseph E O'Tousa
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States
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13
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Asghari Adib E, Smithson LJ, Collins CA. An axonal stress response pathway: degenerative and regenerative signaling by DLK. Curr Opin Neurobiol 2018; 53:110-119. [PMID: 30053694 DOI: 10.1016/j.conb.2018.07.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/02/2018] [Indexed: 02/08/2023]
Abstract
Signaling through the dual leucine zipper-bearing kinase (DLK) is required for injured neurons to initiate new axonal growth; however, activation of this kinase also leads to neuronal degeneration and death in multiple models of injury and neurodegenerative diseases. This has spurred current consideration of DLK as a candidate therapeutic target, and raises a vital question: in what context is DLK a friend or foe to neurons? Here, we review our current understanding of DLK's function and mechanisms in regulating both regenerative and degenerative responses to axonal damage and stress in the nervous system.
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Affiliation(s)
- Elham Asghari Adib
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Laura J Smithson
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Catherine A Collins
- Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
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14
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DISCO interacting protein 2 determines direction of axon projection under the regulation of c-Jun N-terminal kinase in the Drosophila mushroom body. Biochem Biophys Res Commun 2017; 487:116-121. [DOI: 10.1016/j.bbrc.2017.04.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 04/07/2017] [Indexed: 11/21/2022]
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15
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Pathogenic Huntington Alters BMP Signaling and Synaptic Growth through Local Disruptions of Endosomal Compartments. J Neurosci 2017; 37:3425-3439. [PMID: 28235896 DOI: 10.1523/jneurosci.2752-16.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 02/07/2017] [Accepted: 02/13/2017] [Indexed: 01/05/2023] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by expansion of a polyglutamine (polyQ) stretch within the Huntingtin (Htt) protein. Pathogenic Htt disrupts multiple neuronal processes, including gene expression, axonal trafficking, proteasome and mitochondrial activity, and intracellular vesicle trafficking. However, the primary pathogenic mechanism and subcellular site of action for mutant Htt are still unclear. Using a Drosophila HD model, we found that pathogenic Htt expression leads to a profound overgrowth of synaptic connections that correlates directly with the levels of Htt at nerve terminals. Branches of the same nerve containing different levels of Htt show distinct phenotypes, indicating that Htt acts locally to disrupt synaptic growth. The effects of pathogenic Htt on synaptic growth arise from defective synaptic endosomal trafficking, leading to expansion of a recycling endosomal signaling compartment containing Sorting Nexin 16 and a reduction in late endosomes containing Rab11. The disruption of endosomal compartments leads to elevated BMP signaling within nerve terminals, driving excessive synaptic growth. Blocking aberrant signaling from endosomes or reducing BMP activity ameliorates the severity of HD pathology and improves viability. Pathogenic Htt is present largely in a nonaggregated form at synapses, indicating that cytosolic forms of the protein are likely to be the toxic species that disrupt endosomal signaling. Our data indicate that pathogenic Htt acts locally at nerve terminals to alter trafficking between endosomal compartments, leading to defects in synaptic structure that correlate with pathogenesis and lethality in the Drosophila HD model.SIGNIFICANCE STATEMENT Huntington's disease (HD) is the most commonly inherited polyglutamine expansion disorder, but how mutant Huntingtin (Htt) disrupts neuronal function is unclear. In particular, it is unknown within what subcellular compartment pathogenic Htt acts and whether the pathogenesis is associated with aggregated or more soluble forms of the protein. Using a Drosophila HD model, we find that nonaggregated pathogenic Htt acts locally at synaptic terminals to disrupt endosomal compartments, leading to aberrant wiring defects. Genetic manipulations to increase endosomal trafficking of synaptic growth receptors from signaling endosomes or to reduce BMP signaling reduce pathology in this HD model. These data indicate that pathogenic Htt can act locally within nerve terminals to disrupt synaptic endosomal signaling and induce neuropathology.
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16
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Axon Termination, Pruning, and Synaptogenesis in the Giant Fiber System of Drosophila melanogaster Is Promoted by Highwire. Genetics 2017; 205:1229-1245. [PMID: 28100586 DOI: 10.1534/genetics.116.197343] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/20/2016] [Indexed: 11/18/2022] Open
Abstract
The ubiquitin ligase Highwire has a conserved role in synapse formation. Here, we show that Highwire coordinates several facets of central synapse formation in the Drosophila melanogaster giant fiber system, including axon termination, axon pruning, and synaptic function. Despite the similarities to the fly neuromuscular junction, the role of Highwire and the underlying signaling pathways are distinct in the fly's giant fiber system. During development, branching of the giant fiber presynaptic terminal occurs and, normally, the transient branches are pruned away. However, in highwire mutants these ectopic branches persist, indicating that Highwire promotes axon pruning. highwire mutants also exhibit defects in synaptic function. Highwire promotes axon pruning and synaptic function cell-autonomously by attenuating a mitogen-activated protein kinase pathway including Wallenda, c-Jun N-terminal kinase/Basket, and the transcription factor Jun. We also show a novel role for Highwire in non-cell autonomous promotion of synaptic function from the midline glia. Highwire also regulates axon termination in the giant fibers, as highwire mutant axons exhibit severe overgrowth beyond the pruning defect. This excessive axon growth is increased by manipulating Fos expression in the cells surrounding the giant fiber terminal, suggesting that Fos regulates a trans-synaptic signal that promotes giant fiber axon growth.
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17
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Baker ST, Grill B. Defining Minimal Binding Regions in Regulator of Presynaptic Morphology 1 (RPM-1) Using Caenorhabditis elegans Neurons Reveals Differential Signaling Complexes. J Biol Chem 2016; 292:2519-2530. [PMID: 27979965 DOI: 10.1074/jbc.m116.748004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/14/2016] [Indexed: 12/22/2022] Open
Abstract
The intracellular signaling protein regulator of presynaptic morphology 1 (RPM-1) is a conserved regulator of synapse formation and axon termination in Caenorhabditis elegans RPM-1 functions in a ubiquitin ligase complex with the F-box protein FSN-1 and functions through the microtubule binding protein RAE-1. Using a structure-function approach and positive selection for transgenic C. elegans, we explored the biochemical relationship between RPM-1, FSN-1, and RAE-1. This led to the identification of two new domains in RPM-1 that are sufficient for binding to FSN-1, called FSN-1 binding domain 2 (FBD2) and FBD3. Furthermore, we map the RAE-1 binding domain to a much smaller region of RPM-1. Point mutations in RPM-1 that reduce binding to RAE-1 did not affect FSN-1 binding, indicating that RPM-1 utilizes different biochemical mechanisms to bind these molecules. Analysis of RPM-1 protein complexes in the neurons of C. elegans elucidated two further discoveries: FSN-1 binds to RAE-1, and this interaction is not mediated by RPM-1, and RPM-1 binding to FSN-1 and RAE-1 reduces FSN-1·RAE-1 complex formation. These results indicate that RPM-1 uses different mechanisms to recruit FSN-1 and RAE-1 into independent signaling complexes in neurons.
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Affiliation(s)
- Scott T Baker
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458
| | - Brock Grill
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458
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18
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Oliva C, Hassan BA. Receptor Tyrosine Kinases and Phosphatases in Neuronal Wiring: Insights From Drosophila. Curr Top Dev Biol 2016; 123:399-432. [PMID: 28236973 DOI: 10.1016/bs.ctdb.2016.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Tyrosine phosphorylation is at the crossroads of many signaling pathways. Brain wiring is not an exception, and several receptor tyrosine kinases (RTKs) and tyrosine receptor phosphates (RPTPs) have been involved in this process. Considerable work has been done on RTKs, and for many of them, detailed molecular mechanisms and functions in several systems have been characterized. In contrast, RPTPs have been studied considerably less and little is known about their ligands and substrates. In both families, we find redundancy between different members to accomplish particular wiring patterns. Strikingly, some RTKs and RPTPs have lost their catalytic activity during evolution, but not their importance in biological processes. In this regard, we have to keep in mind that these proteins have multiple domains and some of their functions are independent of tyrosine phosphorylation/dephosphorylation. Since RTKs and RPTPs are enzymes involved not only in early stages of axon and dendrite pathfinding but also in synapse formation and physiology, they have a potential as drug targets. Drosophila has been a key model organism in the search of a better understanding of brain wiring, and its sophisticated toolbox is very suitable for studying the function of genes with pleiotropic functions such as RTKs and RPTPs, from wiring to synaptic formation and function. In these review, we mainly cover findings from this model organism and complement them with discoveries in vertebrate systems.
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Affiliation(s)
- Carlos Oliva
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad of Chile, Santiago, Chile.
| | - Bassem A Hassan
- Sorbonne Universités, UPMC Univ Paris 06, Inserm, CNRS, AP-HP, Institut du Cerveau et la Moelle (ICM)-Hôpital Pitié-Salpêtrière, Boulevard de l'Hôpital, Paris, France.
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19
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Zwarts L, Goossens T, Clements J, Kang YY, Callaerts P. Axon Branch-Specific Semaphorin-1a Signaling in Drosophila Mushroom Body Development. Front Cell Neurosci 2016; 10:210. [PMID: 27656129 PMCID: PMC5011136 DOI: 10.3389/fncel.2016.00210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/23/2016] [Indexed: 11/25/2022] Open
Abstract
Correct wiring of the mushroom body (MB) neuropil in the Drosophila brain involves appropriate positioning of different axonal lobes, as well as the sister branches that develop from individual axons. This positioning requires the integration of various guidance cues provided by different cell types, which help the axons find their final positions within the neuropil. Semaphorins are well-known for their conserved roles in neuronal development and axon guidance. We investigated the role of Sema-1a in MB development more closely. We show that Sema-1a is expressed in the MBs as well as surrounding structures, including the glial transient interhemispheric fibrous ring, throughout development. By loss- and gain-of-function experiments, we show that the MB axons display lobe and sister branch-specific Sema-1a signaling, which controls different aspects of axon outgrowth and guidance. Furthermore, we demonstrate that these effects are modulated by the integration of MB intrinsic and extrinsic Sema-1a signaling pathways involving PlexA and PlexB. Finally, we also show a role for neuronal- glial interaction in Sema-1a dependent β-lobe outgrowth.
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Affiliation(s)
- Liesbeth Zwarts
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Tim Goossens
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Jason Clements
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
| | - Yuan Y Kang
- Department of Biology and Biochemistry, University of Houston, Houston, TX USA
| | - Patrick Callaerts
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, LeuvenBelgium; Center for the Biology of Disease, Vlaams Instituut voor Biotechnologie, LeuvenBelgium
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20
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Feoktistov AI, Herman TG. Wallenda/DLK protein levels are temporally downregulated by Tramtrack69 to allow R7 growth cones to become stationary boutons. Development 2016; 143:2983-93. [PMID: 27402706 DOI: 10.1242/dev.134403] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/23/2016] [Indexed: 11/20/2022]
Abstract
Dual leucine zipper kinase (DLK) promotes growth cone motility and must be restrained to ensure normal development. PHR (Pam/Highwire/RPM-1) ubiquitin ligases therefore target DLK for degradation unless axon injury occurs. Overall DLK levels decrease during development, but how DLK levels are regulated within a developing growth cone has not been examined. We analyzed the expression of the fly DLK Wallenda (Wnd) in R7 photoreceptor growth cones as they halt at their targets and become presynaptic boutons. We found that Wnd protein levels are repressed by the PHR protein Highwire (Hiw) during R7 growth cone halting, as has been observed in other systems. However, as R7 growth cones become boutons, Wnd levels are further repressed by a temporally expressed transcription factor, Tramtrack69 (Ttk69). Previously unobserved negative feedback from JNK also contributes to Wnd repression at both time points. We conclude that neurons deploy additional mechanisms to downregulate DLK as they form stable, synaptic connections. We use live imaging to probe the effects of Wnd and Ttk69 on R7 bouton development and conclude that Ttk69 coordinates multiple regulators of this process.
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Affiliation(s)
- Alexander I Feoktistov
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, OR 97403, USA
| | - Tory G Herman
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, OR 97403, USA
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21
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Hao Y, Frey E, Yoon C, Wong H, Nestorovski D, Holzman LB, Giger RJ, DiAntonio A, Collins C. An evolutionarily conserved mechanism for cAMP elicited axonal regeneration involves direct activation of the dual leucine zipper kinase DLK. eLife 2016; 5. [PMID: 27268300 PMCID: PMC4896747 DOI: 10.7554/elife.14048] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/12/2016] [Indexed: 11/13/2022] Open
Abstract
A broadly known method to stimulate the growth potential of axons is to elevate intracellular levels of cAMP, however the cellular pathway(s) that mediate this are not known. Here we identify the Dual Leucine-zipper Kinase (DLK, Wnd in Drosophila) as a critical target and effector of cAMP in injured axons. DLK/Wnd is thought to function as an injury ‘sensor’, as it becomes activated after axonal damage. Our findings in both Drosophila and mammalian neurons indicate that the cAMP effector kinase PKA is a conserved and direct upstream activator of Wnd/DLK. PKA is required for the induction of Wnd signaling in injured axons, and DLK is essential for the regenerative effects of cAMP in mammalian DRG neurons. These findings link two important mediators of responses to axonal injury, DLK/Wnd and cAMP/PKA, into a unified and evolutionarily conserved molecular pathway for stimulating the regenerative potential of injured axons. DOI:http://dx.doi.org/10.7554/eLife.14048.001 Adult mammals typically cannot repair damage to the nerve fibers in their brain or spinal cord. This is because these nerve cells cannot generally grow new nerve fibers. However this inability to regenerate nerve fibers is not set in stone. Instead, it can be unlocked by a second injury in nerves elsewhere in the body, the so-called “peripheral nervous system”. This process relies on an enzyme called DLK, which becomes activated in damaged nerve fibers. But how does DLK ‘sense’ damage to nerve fibers? Injuring the peripheral nervous system causes the levels of a molecule called cAMP to increase in the damaged nerve cells, and the elevated cAMP levels stimulate the nerve fibers to regenerate. However, it was not known if cAMP activates DLK, or if the two act independently of each other. By looking at the regeneration of damaged nerve fibers in fruit fly larvae, Hao et al. now show that the cAMP and DLK signaling pathways are clearly linked. Further experiments with nerve cells from mice and human cells revealed more detail about this link. Together the results showed that another enzyme called PKA activates DLK directly when cAMP levels are high. These findings reveal a unified pathway that is the key to unlocking the regenerative potential of injured nerve fibers, which has been conserved for hundreds of millions of years of evolution. Further work could now ask if the DLK enzyme is involved in the other known roles of cAMP signaling in nerve cells; or if cAMP and PKA activate DLK in other forms of nerve damage, including injuries where nerve fibers normally fail to regenerate. DOI:http://dx.doi.org/10.7554/eLife.14048.002
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Affiliation(s)
- Yan Hao
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Erin Frey
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Choya Yoon
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Hetty Wong
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Douglas Nestorovski
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Lawrence B Holzman
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, United States.,Department of Neurology, University of Michigan School of Medicine, Ann Arbor, United States
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, United States
| | - Catherine Collins
- Department of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
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22
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Grill B, Murphey RK, Borgen MA. The PHR proteins: intracellular signaling hubs in neuronal development and axon degeneration. Neural Dev 2016; 11:8. [PMID: 27008623 PMCID: PMC4806438 DOI: 10.1186/s13064-016-0063-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 03/15/2016] [Indexed: 11/10/2022] Open
Abstract
During development, a coordinated and integrated series of events must be accomplished in order to generate functional neural circuits. Axons must navigate toward target cells, build synaptic connections, and terminate outgrowth. The PHR proteins (consisting of mammalian Phr1/MYCBP2, Drosophila Highwire and C. elegans RPM-1) function in each of these events in development. Here, we review PHR function across species, as well as the myriad of signaling pathways PHR proteins regulate. These findings collectively suggest that the PHR proteins are intracellular signaling hubs, a concept we explore in depth. Consistent with prominent developmental functions, genetic links have begun to emerge between PHR signaling networks and neurodevelopmental disorders, such as autism, schizophrenia and intellectual disability. Finally, we discuss the recent and important finding that PHR proteins regulate axon degeneration, which has further heightened interest in this fascinating group of molecules.
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Affiliation(s)
- Brock Grill
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA.
| | - Rodney K Murphey
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL, 33458, USA
| | - Melissa A Borgen
- Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, FL, 33458, USA
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23
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Siegenthaler D, Enneking EM, Moreno E, Pielage J. L1CAM/Neuroglian controls the axon-axon interactions establishing layered and lobular mushroom body architecture. ACTA ACUST UNITED AC 2015; 208:1003-18. [PMID: 25825519 PMCID: PMC4384726 DOI: 10.1083/jcb.201407131] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The establishment of neuronal circuits depends on the guidance of axons both along and in between axonal populations of different identity; however, the molecular principles controlling axon-axon interactions in vivo remain largely elusive. We demonstrate that the Drosophila melanogaster L1CAM homologue Neuroglian mediates adhesion between functionally distinct mushroom body axon populations to enforce and control appropriate projections into distinct axonal layers and lobes essential for olfactory learning and memory. We addressed the regulatory mechanisms controlling homophilic Neuroglian-mediated cell adhesion by analyzing targeted mutations of extra- and intracellular Neuroglian domains in combination with cell type-specific rescue assays in vivo. We demonstrate independent and cooperative domain requirements: intercalating growth depends on homophilic adhesion mediated by extracellular Ig domains. For functional cluster formation, intracellular Ankyrin2 association is sufficient on one side of the trans-axonal complex whereas Moesin association is likely required simultaneously in both interacting axonal populations. Together, our results provide novel mechanistic insights into cell adhesion molecule-mediated axon-axon interactions that enable precise assembly of complex neuronal circuits.
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Affiliation(s)
- Dominique Siegenthaler
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland University of Basel, 4003 Basel, Switzerland
| | - Eva-Maria Enneking
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland University of Basel, 4003 Basel, Switzerland
| | - Eliza Moreno
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Jan Pielage
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
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24
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Kelly SM, Bienkowski R, Banerjee A, Melicharek DJ, Brewer ZA, Marenda DR, Corbett AH, Moberg KH. The Drosophila ortholog of the Zc3h14 RNA binding protein acts within neurons to pattern axon projection in the developing brain. Dev Neurobiol 2015; 76:93-106. [PMID: 25980665 DOI: 10.1002/dneu.22301] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 12/18/2022]
Abstract
The dNab2 polyadenosine RNA binding protein is the D. melanogaster ortholog of the vertebrate ZC3H14 protein, which is lost in a form of inherited intellectual disability (ID). Human ZC3H14 can rescue D. melanogaster dNab2 mutant phenotypes when expressed in all neurons of the developing nervous system, suggesting that dNab2/ZC3H14 performs well-conserved roles in neurons. However, the cellular and molecular requirements for dNab2/ZC3H14 in the developing nervous system have not been defined in any organism. Here we show that dNab2 is autonomously required within neurons to pattern axon projection from Kenyon neurons into the mushroom bodies, which are required for associative olfactory learning and memory in insects. Mushroom body axons lacking dNab2 project aberrantly across the brain midline and also show evidence of defective branching. Coupled with the prior finding that ZC3H14 is highly expressed in rodent hippocampal neurons, this requirement for dNab2 in mushroom body neurons suggests that dNab2/ZC3H14 has a conserved role in supporting axon projection and branching. Consistent with this idea, loss of dNab2 impairs short-term memory in a courtship conditioning assay. Taken together these results reveal a cell-autonomous requirement for the dNab2 RNA binding protein in mushroom body development and provide a window into potential neurodevelopmental functions of the human ZC3H14 protein.
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Affiliation(s)
- Seth M Kelly
- Department of Biology, College of Wooster, Wooster, Ohio, 44691
| | - Rick Bienkowski
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322.,Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322.,Graduate Program in Genetics and Molecular Biology, Emory University, Atlanta, Georgia, 30322
| | - Ayan Banerjee
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - David J Melicharek
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | | | - Daniel R Marenda
- Department of Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104.,Departments of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, 19104
| | - Anita H Corbett
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia, 30322
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia, 30322
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25
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Reynaud E, Lahaye LL, Boulanger A, Petrova IM, Marquilly C, Flandre A, Martianez T, Privat M, Noordermeer JN, Fradkin LG, Dura JM. Guidance of Drosophila Mushroom Body Axons Depends upon DRL-Wnt Receptor Cleavage in the Brain Dorsomedial Lineage Precursors. Cell Rep 2015; 11:1293-304. [PMID: 25981040 DOI: 10.1016/j.celrep.2015.04.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 03/07/2015] [Accepted: 04/15/2015] [Indexed: 10/23/2022] Open
Abstract
In vivo axon pathfinding mechanisms in the neuron-dense brain remain relatively poorly characterized. We study the Drosophila mushroom body (MB) axons, whose α and β branches connect to different brain areas. We show that the Ryk family WNT5 receptor, DRL (derailed), which is expressed in the dorsomedial lineages, brain structure precursors adjacent to the MBs, is required for MB α branch axon guidance. DRL acts to capture and present WNT5 to MB axons rather than transduce a WNT5 signal. DRL's ectodomain must be cleaved and shed to guide α axons. DRL-2, another Ryk, is expressed within MB axons and functions as a repulsive WNT5 signaling receptor. Finally, our biochemical data support the existence of a ternary complex composed of the cleaved DRL ectodomain, WNT5, and DRL-2. Thus, the interaction of MB-extrinsic and -intrinsic Ryks via their common ligand acts to guide MB α axons.
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Affiliation(s)
- Elodie Reynaud
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Liza L Lahaye
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Ana Boulanger
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Iveta M Petrova
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Claire Marquilly
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Adrien Flandre
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Tania Martianez
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Martin Privat
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
| | - Jasprina N Noordermeer
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands
| | - Lee G Fradkin
- Department of Molecular Cell Biology, Leiden University Medical Center, 2300 RC Leiden, the Netherlands.
| | - Jean-Maurice Dura
- Institute of Human Genetics, UPR1142, CNRS, 141, rue de la Cardonille, 34396 Montpellier, France.
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Sharma J, Baker ST, Turgeon SM, Gurney AM, Opperman KJ, Grill B. Identification of a peptide inhibitor of the RPM-1 · FSN-1 ubiquitin ligase complex. J Biol Chem 2014; 289:34654-66. [PMID: 25326385 DOI: 10.1074/jbc.m114.614065] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Pam/Highwire/RPM-1 (PHR) proteins include: Caenorhabditis elegans RPM-1 (Regulator of Presynaptic Morphology 1), Drosophila Highwire, and murine Phr1. These important regulators of neuronal development function in synapse formation, axon guidance, and axon termination. In mature neurons the PHR proteins also regulate axon degeneration and regeneration. PHR proteins function, in part, through an ubiquitin ligase complex that includes the F-box protein FSN-1 in C. elegans and Fbxo45 in mammals. At present, the structure-function relationships that govern formation of this complex are poorly understood. We cloned 9 individual domains that compose the entire RPM-1 protein sequence and found a single domain centrally located in RPM-1 that is sufficient for binding to FSN-1. Deletion analysis further refined FSN-1 binding to a conserved 97-amino acid region of RPM-1. Mutagenesis identified several conserved motifs and individual amino acids that mediate this interaction. Transgenic overexpression of this recombinant peptide, which we refer to as the RPM-1·FSN-1 complex inhibitory peptide (RIP), yields similar phenotypes and enhancer effects to loss of function in fsn-1. Defects caused by transgenic RIP were suppressed by loss of function in the dlk-1 MAP3K and were alleviated by point mutations that reduce binding to FSN-1. These findings suggest that RIP specifically inhibits the interaction between RPM-1 and FSN-1 in vivo, thereby blocking formation of a functional ubiquitin ligase complex. Our results are consistent with the FSN-1 binding domain of RPM-1 recruiting FSN-1 and a target protein, such as DLK-1, whereas the RING-H2 domain of RPM-1 ubiquitinates the target.
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Affiliation(s)
- Jaiprakash Sharma
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, 33458 and
| | - Scott T Baker
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, 33458 and Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Shane M Turgeon
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, 33458 and
| | - Allison M Gurney
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Karla J Opperman
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, 33458 and
| | - Brock Grill
- From the Department of Neuroscience, The Scripps Research Institute, Scripps Florida, Jupiter, Florida, 33458 and
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Opperman KJ, Grill B. RPM-1 is localized to distinct subcellular compartments and regulates axon length in GABAergic motor neurons. Neural Dev 2014; 9:10. [PMID: 24885325 PMCID: PMC4077836 DOI: 10.1186/1749-8104-9-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 04/24/2014] [Indexed: 01/24/2023] Open
Abstract
Background The PAM/Highwire/RPM-1 (PHR) proteins are conserved signaling proteins that regulate axon length and synapse formation during development. Loss of function in Caenorhabditis elegans rpm-1 results in axon termination and synapse formation defects in the mechanosensory neurons. An explanation for why these two phenotypes are observed in a single neuronal cell has remained absent. Further, it is uncertain whether the axon termination phenotypes observed in the mechanosensory neurons of rpm-1 mutants are unique to this specific type of neuron, or more widespread defects that occur with loss of function in rpm-1. Results Here, we show that RPM-1 is localized to both the mature axon tip and the presynaptic terminals of individual motor neurons and individual mechanosensory neurons. Genetic analysis indicated that GABAergic motor neurons, like the mechanosensory neurons, have both synapse formation and axon termination defects in rpm-1 mutants. RPM-1 functions in parallel with the active zone component SYD-2 (Liprin) to regulate not only synapse formation, but also axon termination in motor neurons. Our analysis of rpm-1−/−; syd-2−/− double mutants also revealed a role for RPM-1 in axon extension. The MAP3K DLK-1 partly mediated RPM-1 function in both axon termination and axon extension, and the relative role of DLK-1 was dictated by the anatomical location of the neuron in question. Conclusions Our findings show that axon termination defects are a core phenotype caused by loss of function in rpm-1, and not unique to the mechanosensory neurons. We show in motor neurons and in mechanosensory neurons that RPM-1 is localized to multiple, distinct subcellular compartments in a single cell. Thus, RPM-1 might be differentially regulated or RPM-1 might differentially control signals in distinct subcellular compartments to regulate multiple developmental outcomes in a single neuron. Our findings provide further support for the previously proposed model that PHR proteins function to coordinate axon outgrowth and termination with synapse formation.
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Affiliation(s)
| | - Brock Grill
- Department of Neuroscience, The Scripps Research Institute - Florida, 130 Scripps Way, Jupiter, FL 33458, USA.
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RPM-1 uses both ubiquitin ligase and phosphatase-based mechanisms to regulate DLK-1 during neuronal development. PLoS Genet 2014; 10:e1004297. [PMID: 24810406 PMCID: PMC4014440 DOI: 10.1371/journal.pgen.1004297] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 02/21/2014] [Indexed: 01/06/2023] Open
Abstract
The Pam/Highwire/RPM-1 (PHR) proteins are key regulators of neuronal development that function in axon extension and guidance, termination of axon outgrowth, and synapse formation. Outside of development, the PHR proteins also regulate axon regeneration and Wallerian degeneration. The PHR proteins function in part by acting as ubiquitin ligases that degrade the Dual Leucine zipper-bearing Kinase (DLK). Here, we show that the Caenorhabditis elegans PHR protein, Regulator of Presynaptic Morphology 1 (RPM-1), also utilizes a phosphatase-based mechanism to regulate DLK-1. Using mass spectrometry, we identified Protein Phosphatase Magnesium/Manganese dependent 2 (PPM-2) as a novel RPM-1 binding protein. Genetic, transgenic, and biochemical studies indicated that PPM-2 functions coordinately with the ubiquitin ligase activity of RPM-1 and the F-box protein FSN-1 to negatively regulate DLK-1. PPM-2 acts on S874 of DLK-1, a residue implicated in regulation of DLK-1 binding to a short, inhibitory isoform of DLK-1 (DLK-1S). Our study demonstrates that PHR proteins function through both phosphatase and ubiquitin ligase mechanisms to inhibit DLK. Thus, PHR proteins are potentially more accurate and sensitive regulators of DLK than originally thought. Our results also highlight an important and expanding role for the PP2C phosphatase family in neuronal development. The molecular mechanisms that govern formation of functional synaptic connections are central to brain development and function. We have used the nematode C. elegans to explore the mechanism of how the intracellular signaling protein RPM-1 regulates neuronal development. Using a combination of proteomic, genetic, transgenic, and biochemical approaches we have shown that RPM-1 functions through a PP2C phosphatase, PPM-2, to regulate the activity of a MAP3 kinase, DLK-1. Our results indicate that a combination of PPM-2 phosphatase activity and RPM-1 ubiquitin ligase activity inhibit DLK-1.
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Wang X, Kim JH, Bazzi M, Robinson S, Collins CA, Ye B. Bimodal control of dendritic and axonal growth by the dual leucine zipper kinase pathway. PLoS Biol 2013; 11:e1001572. [PMID: 23750116 PMCID: PMC3672216 DOI: 10.1371/journal.pbio.1001572] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/16/2013] [Indexed: 02/03/2023] Open
Abstract
Knowledge of the molecular and genetic mechanisms underlying the separation of dendritic and axonal compartments is not only crucial for understanding the assembly of neural circuits, but also for developing strategies to correct defective dendrites or axons in diseases with subcellular precision. Previous studies have uncovered regulators dedicated to either dendritic or axonal growth. Here we investigate a novel regulatory mechanism that differentially directs dendritic and axonal growth within the same neuron in vivo. We find that the dual leucine zipper kinase (DLK) signaling pathway in Drosophila, which consists of Highwire and Wallenda and controls axonal growth, regeneration, and degeneration, is also involved in dendritic growth in vivo. Highwire, an evolutionarily conserved E3 ubiquitin ligase, restrains axonal growth but acts as a positive regulator for dendritic growth in class IV dendritic arborization neurons in the larva. While both the axonal and dendritic functions of highwire require the DLK kinase Wallenda, these two functions diverge through two downstream transcription factors, Fos and Knot, which mediate the axonal and dendritic regulation, respectively. This study not only reveals a previously unknown function of the conserved DLK pathway in controlling dendrite development, but also provides a novel paradigm for understanding how neuronal compartmentalization and the diversity of neuronal morphology are achieved.
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Affiliation(s)
- Xin Wang
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jung Hwan Kim
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mouna Bazzi
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara Robinson
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Catherine A. Collins
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bing Ye
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Tian X, Wu C. The role of ubiquitin-mediated pathways in regulating synaptic development, axonal degeneration and regeneration: insights from fly and worm. J Physiol 2013; 591:3133-43. [PMID: 23613532 DOI: 10.1113/jphysiol.2012.247940] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The covalent attachment of the 76 amino acid peptide ubiquitin to target proteins is a rapid and reversible modification that regulates protein stability, activity and localization. As such, it is a potent mechanism for sculpting the synapse. Recent studies from two genetic model organisms, Caenorhabditis elegans and Drosophila, have provided mounting evidence that ubiquitin-mediated pathways play important roles in controlling the presynaptic size, synaptic elimination and stabilization, synaptic transmission, postsynaptic receptor abundance, axonal degeneration and regeneration. While the data supporting the requirement of ubiquitination/deubiquitination for normal synaptic development and repair are compelling, detailed analyses of signalling events up- and downstream of these ubiquitin modifications are often challenging. This article summarizes the related research conducted in worms and flies and provides insight into the fundamental questions facing this field.
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Affiliation(s)
- Xiaolin Tian
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Breaking it down: the ubiquitin proteasome system in neuronal morphogenesis. Neural Plast 2013; 2013:196848. [PMID: 23476809 PMCID: PMC3586504 DOI: 10.1155/2013/196848] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 12/31/2012] [Indexed: 01/20/2023] Open
Abstract
The ubiquitin-proteasome system (UPS) is most widely known for its role in intracellular protein degradation; however, in the decades since its discovery, ubiquitination has been associated with the regulation of a wide variety of cellular processes. The addition of ubiquitin tags, either as single moieties or as polyubiquitin chains, has been shown not only to mediate degradation by the proteasome and the lysosome, but also to modulate protein function, localization, and endocytosis. The UPS plays a particularly important role in neurons, where local synthesis and degradation work to balance synaptic protein levels at synapses distant from the cell body. In recent years, the UPS has come under increasing scrutiny in neurons, as elements of the UPS have been found to regulate such diverse neuronal functions as synaptic strength, homeostatic plasticity, axon guidance, and neurite outgrowth. Here we focus on recent advances detailing the roles of the UPS in regulating the morphogenesis of axons, dendrites, and dendritic spines, with an emphasis on E3 ubiquitin ligases and their identified regulatory targets.
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A Permissive Role of Mushroom Body α/β Core Neurons in Long-Term Memory Consolidation in Drosophila. Curr Biol 2012; 22:1981-9. [DOI: 10.1016/j.cub.2012.08.048] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 07/18/2012] [Accepted: 08/21/2012] [Indexed: 11/23/2022]
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