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Higashi T, Saito AC, Chiba H. Damage control of epithelial barrier function in dynamic environments. Eur J Cell Biol 2024; 103:151410. [PMID: 38579602 DOI: 10.1016/j.ejcb.2024.151410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 03/27/2024] [Accepted: 03/30/2024] [Indexed: 04/07/2024] Open
Abstract
Epithelial tissues cover the surfaces and lumens of the internal organs of multicellular animals and crucially contribute to internal environment homeostasis by delineating distinct compartments within the body. This vital role is known as epithelial barrier function. Epithelial cells are arranged like cobblestones and intricately bind together to form an epithelial sheet that upholds this barrier function. Central to the restriction of solute and fluid diffusion through intercellular spaces are occluding junctions, tight junctions in vertebrates and septate junctions in invertebrates. As part of epithelial tissues, cells undergo constant renewal, with older cells being replaced by new ones. Simultaneously, the epithelial tissue undergoes relative rearrangement, elongating, and shifting directionally as a whole. The movement or shape changes within the epithelial sheet necessitate significant deformation and reconnection of occluding junctions. Recent advancements have shed light on the intricate mechanisms through which epithelial cells sustain their barrier function in dynamic environments. This review aims to introduce these noteworthy findings and discuss some of the questions that remain unanswered.
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Affiliation(s)
- Tomohito Higashi
- Department of Basic Pathology, Fukushima Medical University, Fukushima 960-1295, Japan.
| | - Akira C Saito
- Department of Basic Pathology, Fukushima Medical University, Fukushima 960-1295, Japan
| | - Hideki Chiba
- Department of Basic Pathology, Fukushima Medical University, Fukushima 960-1295, Japan
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2
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Schleutker R, Luschnig S. Palmitoylation of proteolipid protein M6 promotes tricellular junction assembly in epithelia of Drosophila. J Cell Sci 2024; 137:jcs261916. [PMID: 38345097 DOI: 10.1242/jcs.261916] [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: 12/18/2023] [Accepted: 02/02/2024] [Indexed: 03/21/2024] Open
Abstract
Tricellular junctions (TCJs) seal epithelial cell vertices and are essential for tissue integrity and physiology, but how TCJs are assembled and maintained is poorly understood. In Drosophila, the transmembrane proteins Anakonda (Aka, also known as Bark), Gliotactin (Gli) and M6 organize occluding TCJs. Aka and M6 localize in an interdependent manner to vertices and act jointly to localize Gli, but how these proteins interact to assemble TCJs was not previously known. Here, we show that the proteolipid protein M6 physically interacts with Aka and with itself, and that M6 is palmitoylated on conserved juxta-membrane cysteine residues. This modification promotes vertex localization of M6 and binding to Aka, but not to itself, and becomes essential when TCJ protein levels are reduced. Abolishing M6 palmitoylation leads to delayed localization of M6 and Aka but does not affect the rate of TCJ growth or mobility of M6 or Aka. Our findings suggest that palmitoylation-dependent recruitment of Aka by M6 promotes initiation of TCJ assembly, whereas subsequent TCJ growth relies on different mechanisms that are independent of M6 palmitoylation.
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Affiliation(s)
- Raphael Schleutker
- Institute of Integrative Cell Biology and Physiology, Cells in Motion (CiM) Interfaculty Centre, University of Münster, D-48149 Münster, Germany
| | - Stefan Luschnig
- Institute of Integrative Cell Biology and Physiology, Cells in Motion (CiM) Interfaculty Centre, University of Münster, D-48149 Münster, Germany
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3
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Keramidioti A, Golegou E, Psarra E, Paschalidis N, Kalodimou K, Yamamoto S, Delidakis C, Vakaloglou KM, Zervas CG. Epithelial morphogenesis in the Drosophila egg chamber requires Parvin and ILK. Front Cell Dev Biol 2022; 10:951082. [PMID: 36531940 PMCID: PMC9752845 DOI: 10.3389/fcell.2022.951082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 11/21/2022] [Indexed: 03/11/2024] Open
Abstract
Integrins are the major family of transmembrane proteins that mediate cell-matrix adhesion and have a critical role in epithelial morphogenesis. Integrin function largely depends on the indirect connection of the integrin cytoplasmic tail to the actin cytoskeleton through an intracellular protein network, the integrin adhesome. What is currently unknown is the role of individual integrin adhesome components in epithelia dynamic reorganization. Drosophila egg chamber consists of the oocyte encircled by a monolayer of somatic follicle epithelial cells that undergo specific cell shape changes. Egg chamber morphogenesis depends on a developmental array of cell-cell and cell-matrix signalling events. Recent elegant work on the role of integrins in the Drosophila egg chamber has indicated their essential role in the early stages of oogenesis when the pre-follicle cells assemble into the follicle epithelium. Here, we have focused on the functional requirement of two key integrin adhesome components, Parvin and Integrin-Linked Kinase (ILK). Both proteins are expressed in the developing ovary from pupae to the adult stage and display enriched expression in terminal filament and stalk cells, while their genetic removal from early germaria results in severe disruption of the subsequent oogenesis, leading to female sterility. Combining genetic mosaic analysis of available null alleles for both Parvin and Ilk with conditional rescue utilizing the UAS/Gal4 system, we found that Parvin and ILK are required in pre-follicle cells for germline cyst encapsulation and stalk cell morphogenesis. Collectively, we have uncovered novel developmental functions for both Parvin and ILK, which closely synergize with integrins in epithelia.
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Affiliation(s)
- Athina Keramidioti
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Evgenia Golegou
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Eleni Psarra
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Nikolaos Paschalidis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Konstantina Kalodimou
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Department of Neuroscience (BCM), The Development Disease Models and Therapeutics Graduate Program, Baylor College of Medicine (BCM), Texas Children’s Hospital (TCH), Program in Developmental Biology (BCM), Jan and Dan Duncan Neurological Research Institute, Houston, TX, United States
| | - Christos Delidakis
- Department of Biology, University of Crete, Iraklio, Greece
- Foundation for Research and Technology-Hellas (FORTH), Institute of Molecular Biology and Biotechnology (IMBB), Iraklio, Greece
| | - Katerina M. Vakaloglou
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Christos G. Zervas
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
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Fernández EM, Cutraro YB, Adams J, Monteleone MC, Hughes KJ, Frasch AC, Vidal-Gadea AG, Brocco MA. Neuronal membrane glycoprotein (nmgp-1) gene deficiency affects chemosensation-related behaviors, dauer exit and egg-laying in Caenorhabditis elegans. J Neurochem 2021; 160:234-255. [PMID: 34816431 DOI: 10.1111/jnc.15543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 11/10/2021] [Accepted: 11/14/2021] [Indexed: 11/30/2022]
Abstract
The nervous system monitors the environment to maintain homeostasis, which can be affected by stressful conditions. Using mammalian models of chronic stress, we previously observed altered brain levels of GPM6A, a protein involved in neuronal morphology. However, GPM6A's role in systemic stress responses remains unresolved. The nematode Caenorhabditis elegans expresses a GPM6A ortholog, the neuronal membrane glycoprotein 1 (NMGP-1). Because of the shared features between nematode and mammalian nervous systems and the vast genetic tools available in C. elegans, we used the worm to elucidate the role of GPM6A in the stress response. We first identified nmgp-1 expression in different amphid and phasmid neurons. To understand the nmgp-1 role, we characterized the behavior of nmgp-1(RNAi) animals and two nmgp-1 mutant alleles. Compared to control animals, mutant and RNAi-treated worms exhibited increased recovery time from the stress-resistant dauer stage, altered SDS chemosensation and reduced egg-laying rate resulting in egg retention (bag-of-worms phenotype). Silencing of nmgp-1 expression induced morphological abnormalities in the ASJ sensory neurons, partly responsible for dauer exit. These results indicate that nmgp-1 is required for neuronal morphology and for behaviors associated with chemosensation. Finally, we propose nmgp-1 mutants as a tool to screen drugs for human nervous system pathologies.
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Affiliation(s)
- Eliana M Fernández
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires, Argentina
| | - Yamila B Cutraro
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires, Argentina
| | - Jessica Adams
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Melisa C Monteleone
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires, Argentina
| | - Kiley J Hughes
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Alberto C Frasch
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires, Argentina
| | | | - Marcela A Brocco
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín, Buenos Aires, Argentina
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Row S, Huang YC, Deng WM. Developmental regulation of oocyte lipid intake through 'patent' follicular epithelium in Drosophila melanogaster. iScience 2021; 24:102275. [PMID: 33817579 PMCID: PMC8005764 DOI: 10.1016/j.isci.2021.102275] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 02/19/2021] [Accepted: 03/02/2021] [Indexed: 01/20/2023] Open
Abstract
Epithelia form protective permeability barriers that selectively allow the exchange of material while maintaining tissue integrity under extreme mechanical, chemical, and bacterial loads. Here, we report in the Drosophila follicular epithelium a developmentally regulated and evolutionarily conserved process "patency", wherein a breach is created in the epithelium at tricellular contacts during mid-vitellogenesis. In Drosophila, patency exhibits a strict temporal range potentially delimited by the transcription factor Tramtrack69 and a spatial pattern influenced by the dorsal-anterior signals of the follicular epithelium. Crucial for growth and lipid uptake by the oocyte, patency is also exploited by endosymbionts such as Spiroplasma pulsonii. Our findings reveal an evolutionarily conserved and developmentally regulated non-typical epithelial function in a classic model system.
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Affiliation(s)
- Sarayu Row
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Yi-Chun Huang
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Wu-Min Deng
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Rice C, De O, Alhadyian H, Hall S, Ward RE. Expanding the Junction: New Insights into Non-Occluding Roles for Septate Junction Proteins during Development. J Dev Biol 2021; 9:11. [PMID: 33801162 PMCID: PMC8006247 DOI: 10.3390/jdb9010011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/17/2022] Open
Abstract
The septate junction (SJ) provides an occluding function for epithelial tissues in invertebrate organisms. This ability to seal the paracellular route between cells allows internal tissues to create unique compartments for organ function and endows the epidermis with a barrier function to restrict the passage of pathogens. Over the past twenty-five years, numerous investigators have identified more than 30 proteins that are required for the formation or maintenance of the SJs in Drosophila melanogaster, and have determined many of the steps involved in the biogenesis of the junction. Along the way, it has become clear that SJ proteins are also required for a number of developmental events that occur throughout the life of the organism. Many of these developmental events occur prior to the formation of the occluding junction, suggesting that SJ proteins possess non-occluding functions. In this review, we will describe the composition of SJs, taking note of which proteins are core components of the junction versus resident or accessory proteins, and the steps involved in the biogenesis of the junction. We will then elaborate on the functions that core SJ proteins likely play outside of their role in forming the occluding junction and describe studies that provide some cell biological perspectives that are beginning to provide mechanistic understanding of how these proteins function in developmental contexts.
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Affiliation(s)
- Clinton Rice
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA; (C.R.); (H.A.)
| | - Oindrila De
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA;
| | - Haifa Alhadyian
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA; (C.R.); (H.A.)
| | | | - Robert E. Ward
- Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA;
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The Transmembrane Proteins M6 and Anakonda Cooperate to Initiate Tricellular Junction Assembly in Epithelia of Drosophila. Curr Biol 2020; 30:4254-4262.e5. [DOI: 10.1016/j.cub.2020.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/30/2020] [Accepted: 08/03/2020] [Indexed: 11/18/2022]
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Interplay between Anakonda, Gliotactin, and M6 for Tricellular Junction Assembly and Anchoring of Septate Junctions in Drosophila Epithelium. Curr Biol 2020; 30:4245-4253.e4. [PMID: 32857971 DOI: 10.1016/j.cub.2020.07.090] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 11/22/2022]
Abstract
In epithelia, tricellular junctions (TCJs) serve as pivotal sites for barrier function and integration of both biochemical and mechanical signals [1-3]. In Drosophila, TCJs are composed of the transmembrane protein Sidekick at the adherens junction (AJ) level, which plays a role in cell-cell contact rearrangement [4-6]. At the septate junction (SJ) level, TCJs are formed by Gliotactin (Gli) [7], Anakonda (Aka) [8, 9], and the Myelin proteolipid protein (PLP) M6 [10, 11]. Despite previous data on TCJ organization [12-14], TCJ assembly, composition, and links to adjacent bicellular junctions (BCJs) remain poorly understood. Here, we have characterized the making of TCJs within the plane of adherens junctions (tricellular adherens junction [tAJ]) and the plane of septate junctions (tricellular septate junction [tSJ]) and report that their assembly is independent of each other. Aka and M6, whose localizations are interdependent, act upstream to localize Gli. In turn, Gli stabilizes Aka at tSJ. Moreover, tSJ components are not only essential at vertex, as we found that loss of tSJ integrity induces micron-length bicellular SJ (bSJ) deformations. This phenotype is associated with the disappearance of SJ components at tricellular contacts, indicating that bSJs are no longer connected to tSJs. Reciprocally, SJ components are required to restrict the localization of Aka and Gli at vertex. We propose that tSJs function as pillars to anchor bSJs to ensure the maintenance of tissue integrity in Drosophila proliferative epithelia.
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Molecular organization, regulation and function of tricellular junctions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183143. [DOI: 10.1016/j.bbamem.2019.183143] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/21/2019] [Accepted: 11/29/2019] [Indexed: 02/07/2023]
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Gregor A, Kramer JM, van der Voet M, Schanze I, Uebe S, Donders R, Reis A, Schenck A, Zweier C. Altered GPM6A/M6 dosage impairs cognition and causes phenotypes responsive to cholesterol in human and Drosophila. Hum Mutat 2015; 35:1495-505. [PMID: 25224183 DOI: 10.1002/humu.22697] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 09/05/2014] [Indexed: 12/28/2022]
Abstract
Glycoprotein M6A (GPM6A) is a neuronal transmembrane protein of the PLP/DM20 (proteolipid protein) family that associates with cholesterol-rich lipid rafts and promotes filopodia formation. We identified a de novo duplication of the GPM6A gene in a patient with learning disability and behavioral anomalies. Expression analysis in blood lymphocytes showed increased GPM6A levels. An increase of patient-derived lymphoblastoid cells carrying membrane protrusions supports a functional effect of this duplication. To study the consequences of GPM6A dosage alterations in an intact nervous system, we employed Drosophila melanogaster as a model organism. We found that knockdown of Drosophila M6, the sole member of the PLP family in flies, in the wing, and whole organism causes malformation and lethality, respectively. These phenotypes as well as the protrusions of patient-derived lymphoblastoid cells with increased GPM6A levels can be alleviated by cholesterol supplementation. Notably, overexpression as well as loss of M6 in neurons specifically compromises long-term memory in the courtship conditioning paradigm. Our findings thus indicate a critical role of correct GPM6A/M6 levels for cognitive function and support a role of the GPM6A duplication for the patient's phenotype. Together with other recent findings, this study highlights compromised cholesterol homeostasis as a recurrent feature in cognitive phenotypes.
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Affiliation(s)
- Anne Gregor
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Formoso K, García MD, Frasch AC, Scorticati C. Filopodia formation driven by membrane glycoprotein M6a depends on the interaction of its transmembrane domains. J Neurochem 2015; 134:499-512. [PMID: 25940868 DOI: 10.1111/jnc.13153] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 04/21/2015] [Accepted: 04/24/2015] [Indexed: 12/19/2022]
Abstract
Membrane glycoprotein M6a, which belongs to the tetraspan proteolipid protein family, promotes structural plasticity in neurons and cell lines by unknown mechanisms. This glycoprotein is encoded by Gpm6a, a stress-regulated gene. The hippocampus of animals chronically stressed by either psychosocial or physical stressors shows decreased M6a expression. Stressed Gpm6a-null mice develop a claustrophobia-like phenotype. In humans, de novo duplication of GPM6A results in learning/behavioral abnormalities, and two single-nucleotide polymorphisms (SNPs) in the non-coding region are linked to mood disorders. Here, we studied M6a dimerization in neuronal membranes and its functional relevance. We showed that the self-interaction of M6a transmembrane domains (TMDs) might be driving M6a dimerization, which is required to induce filopodia formation. Glycine mutants located in TMD2 and TMD4 of M6a affected its dimerization, thus preventing M6a-induced filopodia formation in neurons. In silico analysis of three non-synonymous SNPs located in the coding region of TMDs suggested that these mutations induce protein instability. Indeed, these SNPs prevented M6a from being functional in neurons, owing to decreased stability, dimerization or improper folding. Interestingly, SNP3 (W141R), which caused endoplasmic reticulum retention, is equivalent to that mutated in PLP1, W161L, which causes demyelinating Pelizaeus-Merzbacher disease. In this work we analyzed the functional contribution of transmembrane domains (TMDs) of the neuronal membrane glycoprotein M6a. We determined that certain glycines present in TMD2 and TMD4 are critical for filopodia induction in neurons. In addition, three nsSNPs located in the coding region of TMD2 and TMD3 of GPM6A impair M6a function by affecting its stability, folding and dimer formation.
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Affiliation(s)
- Karina Formoso
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Micaela D García
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Alberto C Frasch
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
| | - Camila Scorticati
- Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Martín, Buenos Aires, Argentina
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Zappia MP, Bernabo G, Billi SC, Frasch AC, Ceriani MF, Brocco MA. A role for the membrane protein M6 in the Drosophila visual system. BMC Neurosci 2012; 13:78. [PMID: 22762289 PMCID: PMC3438117 DOI: 10.1186/1471-2202-13-78] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 06/26/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Members of the proteolipid protein family, including the four-transmembrane glycoprotein M6a, are involved in neuronal plasticity in mammals. Results from our group previously demonstrated that M6, the only proteolipid protein expressed in Drosophila, localizes to the cell membrane in follicle cells. M6 loss triggers female sterility, which suggests a role for M6 in follicular cell remodeling. These results were the basis of the present study, which focused on the function and requirements of M6 in the fly nervous system. RESULTS The present study identified two novel, tissue-regulated M6 isoforms with variable N- and C- termini, and showed that M6 is the functional fly ortholog of Gpm6a. In the adult brain, the protein was localized to several neuropils, such as the optic lobe, the central complex, and the mushroom bodies. Interestingly, although reduced M6 levels triggered a mild rough-eye phenotype, hypomorphic M6 mutants exhibited a defective response to light. CONCLUSIONS Based on its ability to induce filopodium formation we propose that M6 is key in cell remodeling processes underlying visual system function. These results bring further insight into the role of M6/M6a in biological processes involving neuronal plasticity and behavior in flies and mammals.
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Affiliation(s)
- María Paula Zappia
- Instituto de Investigaciones Biotecnológicas Dr, Rodolfo Ugalde, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de General San Martín, IIB, INTECH, CONICET-UNSAM, San Martín, Provincia de Buenos Aires, Argentina.
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