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Iwanaga R, Yahagi N, Hakeda-Suzuki S, Suzuki T. Cell adhesion and actin dynamics factors promote axonal extension and synapse formation in transplanted Drosophila photoreceptor cells. Dev Growth Differ 2024; 66:205-218. [PMID: 38403285 DOI: 10.1111/dgd.12916] [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: 11/24/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 02/27/2024]
Abstract
Vision is formed by the transmission of light stimuli to the brain through axons extending from photoreceptor cells. Damage to these axons leads to loss of vision. Despite research on neural circuit regeneration through transplantation, achieving precise axon projection remains challenging. To achieve optic nerve regeneration by transplantation, we employed the Drosophila visual system. We previously established a transplantation method for Drosophila utilizing photoreceptor precursor cells extracted from the eye disc. However, little axonal elongation of transplanted cells into the brain, the lamina, was observed. We verified axonal elongation to the lamina by modifying the selection process for transplanted cells. Moreover, we focused on N-cadherin (Ncad), a cell adhesion factor, and Twinstar (Tsr), which has been shown to promote actin reorganization and induce axon elongation in damaged nerves. Overexpression of Ncad and tsr promoted axon elongation to the lamina, along with presynaptic structure formation in the elongating axons. Furthermore, overexpression of Neurexin-1 (Nrx-1), encoding a protein identified as a synaptic organizer, was found to not only promote presynapse formation but also enhance axon elongation. By introducing Ncad, tsr, and Nrx-1, we not only successfully achieved axonal projection of transplanted cells to the brain beyond the retina, but also confirmed the projection of transplanted cells into a deeper ganglion, the medulla. The present study offers valuable insights to realize regeneration through transplantation in a more complex nervous system.
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Affiliation(s)
- Riku Iwanaga
- School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Japan
| | - Nagisa Yahagi
- School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Japan
| | - Satoko Hakeda-Suzuki
- School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Japan
- Research Initiatives and Promotion Organization, Yokohama National University, Yokohama, Japan
| | - Takashi Suzuki
- School of Life Science and Technology, Tokyo Institute of Technology, Yokahama, Japan
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Chen S, Venkatesan A, Lin YQ, Xie J, Neely G, Banerjee S, Bhat MA. Drosophila Homolog of the Human Carpenter Syndrome Linked Gene, MEGF8, Is Required for Synapse Development and Function. J Neurosci 2022; 42:7016-7030. [PMID: 35944997 PMCID: PMC9480877 DOI: 10.1523/jneurosci.0442-22.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 11/21/2022] Open
Abstract
Drosophila multiple epidermal growth factor-like domains 8 (dMegf8) is a homolog of human MEGF8 MEGF8 encodes a multidomain transmembrane protein which is highly conserved across species. In humans, MEGF8 mutations cause a rare genetic disorder called Carpenter syndrome, which is frequently associated with abnormal left-right patterning, cardiac defects, and learning disabilities. MEGF8 is also associated with psychiatric disorders. Despite its clinical relevance, MEGF8 remains poorly characterized; and although it is highly conserved, studies on animal models of Megf8 are also very limited. The presence of intellectual disabilities in Carpenter syndrome patients and association of MEGF8 with psychiatric disorders indicate that mutations in MEGF8 cause underlying defects in synaptic structure and functions. In this study, we investigated the role of Drosophila dMegf8 in glutamatergic synapses of the larval neuromuscular junctions (NMJ) in both males and females. We show that dMegf8 localizes to NMJ synapses and is required for proper synaptic growth. dMegf8 mutant larvae and adults show severe motor coordination deficits. At the NMJ, dMegf8 mutants show altered localization of presynaptic and postsynaptic proteins, defects in synaptic ultrastructure, and neurotransmission. Interestingly, dMegf8 mutants have reduced levels of the Type II BMP receptor Wishful thinking (Wit). dMegf8 displays genetic interactions with neurexin-1 (dnrx) and wit, and in association with Dnrx and Wit plays an essential role in synapse organization. Our studies provide insights into human MEGF8 functions and potentially into mechanisms that may underlie intellectual disabilities observed in Carpenter syndrome as well as MEGF8-related synaptic structural and/or functional deficits in psychiatric disorders.SIGNIFICANCE STATEMENT Carpenter syndrome, known for over a century now, is a genetic disorder linked to mutations in Multiple Epidermal Growth Factor-like Domains 8 (MEGF8) gene and associated with intellectual disabilities among other symptoms. MEGF8 is also associated with psychiatric disorders. Despite the high genetic conservation and clinical relevance, the functions of MEGF8 remain largely uncharacterized. Patients with intellectual disabilities and psychiatric diseases often have an underlying defect in synaptic structure and function. This work defines the role of the fly homolog of human MEGF8, dMegf8, in glutamatergic synapse growth, organization, and function and provide insights into potential functions of MEGF8 in human central synapses and synaptic mechanisms that may underlie psychiatric disorders and intellectual disabilities seen in Carpenter syndrome.
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Affiliation(s)
- Shuting Chen
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
- Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China
| | - Anand Venkatesan
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
| | - Yong Qi Lin
- Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales Australia 2006
| | - Jing Xie
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
- Second Xiangya Hospital of Central South University, Changsha, Hunan 410011, China
| | - Gregory Neely
- Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales Australia 2006
| | - Swati Banerjee
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
| | - Manzoor A Bhat
- Department of Cellular and Integrative Physiology, Joe R. and Teresa Lozano Long School of Medicine, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229
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Jeong HS, Kim HJ, Kim DH, Chung KW, Choi BO, Lee JE. Therapeutic Potential of CKD-504, a Novel Selective Histone Deacetylase 6 Inhibitor, in a Zebrafish Model of Neuromuscular Junction Disorders. Mol Cells 2022; 45:231-242. [PMID: 35356895 PMCID: PMC9001154 DOI: 10.14348/molcells.2022.5005] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/19/2021] [Accepted: 12/25/2021] [Indexed: 11/27/2022] Open
Abstract
The neuromuscular junction (NMJ), which is a synapse for signal transmission from motor neurons to muscle cells, has emerged as an important region because of its association with several peripheral neuropathies. In particular, mutations in GARS that affect the formation of NMJ result in Charcot-Marie-Tooth disease and distal hereditary motor neuropathy. These disorders are mainly considered to be caused by neuronal axon abnormalities; however, no treatment is currently available. Therefore, in order to determine whether the NMJ could be targeted to treat neurodegenerative disorders, we investigated the NMJ recovery effect of HDAC6 inhibitors, which have been used in the treatment of several peripheral neuropathies. In the present study, we demonstrated that HDAC6 inhibition was sufficient to enhance movement by restoring NMJ impairments observed in a zebrafish disease model. We found that CKD-504, a novel HDAC6 inhibitor, was effective in repairing NMJ defects, suggesting that treatment of neurodegenerative diseases via NMJ targeting is possible.
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Affiliation(s)
- Hui Su Jeong
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University, Seoul 06351, Korea
| | - Hye Jin Kim
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University, Seoul 06351, Korea
| | - Deok-Ho Kim
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ki Wha Chung
- Department of Biological Sciences, Kongju National University, Gongju 32588, Korea
| | - Byung-Ok Choi
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University, Seoul 06351, Korea
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Ji Eun Lee
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences & Technology, Sungkyunkwan University, Seoul 06351, Korea
- Samsung Biomedical Research Institute, Samsung Medical Center, Seoul 06351, Korea
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Abstract
Neurexin-3 is primarily localized in the presynaptic membrane and forms complexes with various ligands located in the postsynaptic membrane. Neurexin-3 has important roles in synapse development and synapse functions. Neurexin-3 mediates excitatory presynaptic differentiation by interacting with leucine-rich-repeat transmembrane neuronal proteins. Meanwhile, neurexin-3 modulates the expression of presynaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors and γ-aminobutyric acid A receptors by interacting with neuroligins at excitatory and inhibitory synapses. Numerous studies have documented the potential contribution of neurexin-3 to neurodegenerative and neuropsychiatric disorders, such as Alzheimer's disease, addiction behaviors, and other diseases, which raises hopes that understanding the mechanisms of neurexin-3 may hold the key to developing new strategies for related illnesses. This review comprehensively covers the literature to provide current knowledge of the structure, function, and clinical role of neurexin-3.
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Naik AS, Lin JM, Taroc EZM, Katreddi RR, Frias JA, Lemus AA, Sammons MA, Forni PE. Smad4-dependent morphogenic signals control the maturation and axonal targeting of basal vomeronasal sensory neurons to the accessory olfactory bulb. Development 2020; 147:147/8/dev184036. [PMID: 32341026 PMCID: PMC7197725 DOI: 10.1242/dev.184036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 03/10/2020] [Indexed: 12/31/2022]
Abstract
The vomeronasal organ (VNO) contains two main types of vomeronasal sensory neurons (VSNs) that express distinct vomeronasal receptor (VR) genes and localize to specific regions of the neuroepithelium. Morphogenic signals are crucial in defining neuronal identity and network formation; however, if and what signals control maturation and homeostasis of VSNs is largely unexplored. Here, we found transforming growth factor β (TGFβ) and bone morphogenetic protein (BMP) signal transduction in postnatal mice, with BMP signaling being restricted to basal VSNs and at the marginal zones of the VNO: the site of neurogenesis. Using different Smad4 conditional knockout mouse models, we disrupted canonical TGFβ/BMP signaling in either maturing basal VSNs (bVSNs) or all mature VSNs. Smad4 loss of function in immature bVSNs compromises dendritic knob formation, pheromone induced activation, correct glomeruli formation in the accessory olfactory bulb (AOB) and survival. However, Smad4 loss of function in all mature VSNs only compromises correct glomeruli formation in the posterior AOB. Our results indicate that Smad4-mediated signaling drives the functional maturation and connectivity of basal VSNs. Summary: Genetic disruption of TGFβ/BMP signaling in maturing basal vomeronasal sensory neurons (VSNs) or in all mature VSNs indicates that Smad4 signaling drives maturation and connectivity of basal VSNs.
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Affiliation(s)
- Ankana S Naik
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Jennifer M Lin
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Ed Zandro M Taroc
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Raghu R Katreddi
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Jesus A Frias
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Alex A Lemus
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Morgan A Sammons
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
| | - Paolo E Forni
- Department of Biological Sciences; The RNA Institute; University at Albany, State University of New York, Albany, NY 12222, USA
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Berke B, Le L, Keshishian H. Target-dependent retrograde signaling mediates synaptic plasticity at the Drosophila neuromuscular junction. Dev Neurobiol 2020; 79:895-912. [PMID: 31950660 DOI: 10.1002/dneu.22731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 12/26/2022]
Abstract
Neurons that innervate multiple targets often establish synapses with target-specific strengths, and local forms of synaptic plasticity. We have examined the molecular-genetic mechanisms that allow a single Drosophila motoneuron, the ventral Common Exciter (vCE), to establish connections with target-specific properties at its various synaptic partners. By driving transgenes in a subset of vCE's targets, we found that individual target cells are able to independently control the properties of vCE's innervating branch and synapses. This is achieved by means of a trans-synaptic growth factor secreted by the target cell. At the larval neuromuscular junction, postsynaptic glutamate receptor activity stimulates the release of the BMP4/5/6 homolog Glass bottom boat (Gbb). As larvae mature and motoneuron terminals grow, Gbb activates the R-Smad transcriptional regulator phosphorylated Mad (pMad) to facilitate presynaptic development. We found that manipulations affecting glutamate receptors or Gbb within subsets of target muscles led to local effects either specific to the manipulated muscle or by a limited gradient within the presynaptic branches. While presynaptic development depends on pMad transcriptional activity within the motoneuron nucleus, we find that the Gbb growth factor may also act locally within presynaptic terminals. Local Gbb signaling and presynaptic pMad accumulation within boutons may therefore participate in a "synaptic tagging" mechanism, to influence synaptic growth and plasticity in Drosophila.
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Affiliation(s)
- Brett Berke
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
| | - Linh Le
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | - Haig Keshishian
- Molecular, Cellular, and Developmental Biology Department, Yale University, New Haven, CT, USA
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Bellosta P, Soldano A. Dissecting the Genetics of Autism Spectrum Disorders: A Drosophila Perspective. Front Physiol 2019; 10:987. [PMID: 31481894 PMCID: PMC6709880 DOI: 10.3389/fphys.2019.00987] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 07/18/2019] [Indexed: 01/10/2023] Open
Abstract
Autism Spectrum Disorder (ASD) is a complex group of multi-factorial developmental disorders that leads to communication and behavioral defects. Genetic alterations have been identified in around 20% of ASD patients and the use of genetic models, such as Drosophila melanogaster, has been of paramount importance in deciphering the significance of these alterations. In fact, many of the ASD associated genes, such as FMR1, Neurexin, Neuroligins and SHANK encode for proteins that have conserved functions in neurons and during synapse development, both in humans and in the fruit fly. Drosophila is a prominent model in neuroscience due to the conserved genetic networks that control neurodevelopmental processes and to the ease of manipulating its genetics. In the present review we will describe recent advances in the field of ASD with a particular focus on the characterization of genes where the use of Drosophila has been fundamental to better understand their function.
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Affiliation(s)
- Paola Bellosta
- Laboratory of Metabolism of Cell Growth and Neuronal Survival, Department of Cellular, Computational and Integrative Biology (CIBio), University of Trento, Trento, Italy.,Department of Medicine, New York University Langone Medical Center, New York, NY, United States
| | - Alessia Soldano
- Laboratory of Translational Genomics, Department of Cellular, Computational and Integrative Biology (CIBio), University of Trento, Trento, Italy
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