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The retinal pigmentation pathway in human albinism: Not so black and white. Prog Retin Eye Res 2022; 91:101091. [PMID: 35729001 DOI: 10.1016/j.preteyeres.2022.101091] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/24/2022] [Accepted: 05/26/2022] [Indexed: 12/16/2022]
Abstract
Albinism is a pigment disorder affecting eye, skin and/or hair. Patients usually have decreased melanin in affected tissues and suffer from severe visual abnormalities, including foveal hypoplasia and chiasmal misrouting. Combining our data with those of the literature, we propose a single functional genetic retinal signalling pathway that includes all 22 currently known human albinism disease genes. We hypothesise that defects affecting the genesis or function of different intra-cellular organelles, including melanosomes, cause syndromic forms of albinism (Hermansky-Pudlak (HPS) and Chediak-Higashi syndrome (CHS)). We put forward that specific melanosome impairments cause different forms of oculocutaneous albinism (OCA1-8). Further, we incorporate GPR143 that has been implicated in ocular albinism (OA1), characterised by a phenotype limited to the eye. Finally, we include the SLC38A8-associated disorder FHONDA that causes an even more restricted "albinism-related" ocular phenotype with foveal hypoplasia and chiasmal misrouting but without pigmentation defects. We propose the following retinal pigmentation pathway, with increasingly specific genetic and cellular defects causing an increasingly specific ocular phenotype: (HPS1-11/CHS: syndromic forms of albinism)-(OCA1-8: OCA)-(GPR143: OA1)-(SLC38A8: FHONDA). Beyond disease genes involvement, we also evaluate a range of (candidate) regulatory and signalling mechanisms affecting the activity of the pathway in retinal development, retinal pigmentation and albinism. We further suggest that the proposed pigmentation pathway is also involved in other retinal disorders, such as age-related macular degeneration. The hypotheses put forward in this report provide a framework for further systematic studies in albinism and melanin pigmentation disorders.
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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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Muraoka S, DeLeo AM, Sethi MK, Yukawa‐Takamatsu K, Yang Z, Ko J, Hogan JD, Ruan Z, You Y, Wang Y, Medalla M, Ikezu S, Chen M, Xia W, Gorantla S, Gendelman HE, Issadore D, Zaia J, Ikezu T. Proteomic and biological profiling of extracellular vesicles from Alzheimer's disease human brain tissues. Alzheimers Dement 2020; 16:896-907. [PMID: 32301581 PMCID: PMC7293582 DOI: 10.1002/alz.12089] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/05/2019] [Accepted: 01/15/2020] [Indexed: 12/31/2022]
Abstract
Introduction Extracellular vesicles (EVs) from human Alzheimer's disease (AD) biospecimens contain amyloid beta (Aβ) peptide and tau. While AD EVs are known to affect brain disease pathobiology, their biochemical and molecular characterizations remain ill defined. Methods EVs were isolated from the cortical gray matter of 20 AD and 18 control brains. Tau and Aβ levels were measured by immunoassay. Differentially expressed EV proteins were assessed by quantitative proteomics and machine learning. Results Levels of pS396 tau and Aβ1–42 were significantly elevated in AD EVs. High levels of neuron‐ and glia‐specific factors are detected in control and AD EVs, respectively. Machine learning identified ANXA5, VGF, GPM6A, and ACTZ in AD EV compared to controls. They distinguished AD EVs from controls in the test sets with 88% accuracy. Discussion In addition to Aβ and tau, ANXA5, VGF, GPM6A, and ACTZ are new signature proteins in AD EVs.
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Affiliation(s)
- Satoshi Muraoka
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Annina M. DeLeo
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Manveen K. Sethi
- Department of BiochemistryBoston University School of Medicine Boston Massachusetts USA
| | - Kayo Yukawa‐Takamatsu
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Zijian Yang
- Department of BioengineeringUniversity of Pennsylvania Philadelphia Pennsylvania USA
| | - Jina Ko
- Department of BioengineeringUniversity of Pennsylvania Philadelphia Pennsylvania USA
| | - John D. Hogan
- Program in BioinformaticsBoston University Boston Massachusetts USA
| | - Zhi Ruan
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Yang You
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Yuzhi Wang
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Maria Medalla
- Department of Anatomy and NeurobiologyBoston University School of Medicine Boston Massachusetts USA
| | - Seiko Ikezu
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
| | - Mei Chen
- Geriatric ResearchEducation and Clinical CenterEdith Nourse Rogers Memorial Veterans Hospital Bedford Massachusetts USA
| | - Weiming Xia
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
- Geriatric ResearchEducation and Clinical CenterEdith Nourse Rogers Memorial Veterans Hospital Bedford Massachusetts USA
| | - Santhi Gorantla
- Department of Pharmacology and Experimental NeurosciencesUniversity of Nebraska Medical Center Omaha Nebraska USA
| | - Howard E. Gendelman
- Department of Pharmacology and Experimental NeurosciencesUniversity of Nebraska Medical Center Omaha Nebraska USA
| | - David Issadore
- Department of BioengineeringUniversity of Pennsylvania Philadelphia Pennsylvania USA
| | - Joseph Zaia
- Department of BiochemistryBoston University School of Medicine Boston Massachusetts USA
| | - Tsuneya Ikezu
- Department of Pharmacology and Experimental TherapeuticsBoston University School of Medicine Boston Massachusetts USA
- Department of NeurologyBoston University School of Medicine Boston Massachusetts USA
- Center for Systems NeuroscienceBoston University Boston Massachusetts USA
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Rosas NM, Alvarez Juliá A, Alzuri SE, Frasch AC, Fuchsova B. Alanine Scanning Mutagenesis of the C-Terminal Cytosolic End of Gpm6a Identifies Key Residues Essential for the Formation of Filopodia. Front Mol Neurosci 2018; 11:314. [PMID: 30233315 PMCID: PMC6131581 DOI: 10.3389/fnmol.2018.00314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/15/2018] [Indexed: 12/14/2022] Open
Abstract
Neuronal membrane glycoprotein M6a (Gpm6a) is a protein with four transmembrane regions and the N- and the C-ends facing the cytosol. It functions in processes of neuronal development, outgrowth of neurites, and formation of filopodia, spines, and synapsis. Molecular mechanisms by which Gpm6a acts in these processes are not fully comprehended. Structural similarities of Gpm6a with tetraspanins led us to hypothesize that, similarly to tetraspanins, the cytoplasmic tails function as connections with cytoskeletal and/or signaling proteins. Here, we demonstrate that the C- but not the N-terminal cytosolic end of Gpm6a is required for the formation of filopodia by Gpm6a in cultured neurons from rat hippocampus and in neuroblastoma cells N2a. Further immunofluorescence microcopy and flow cytometry analysis show that deletion of neither the N- nor the C-terminal intracellular domains interferes with the recognition of Gpm6a by the function-blocking antibody directed against the extracellular part of Gpm6a. Expression levels of both truncation mutants were not affected but we observed decrease in the amount of both truncated proteins on cell surface suggesting that the incapacity of the Gpm6a lacking C-terminus to induce filopodium formation is not due to the lower amount of Gpm6a on cell surface. Following colocalization assays shows that deletion of the C- but not the N-terminus diminishes the association of Gpm6a with clathrin implying involvement of clathrin-mediated trafficking events. Next, using comprehensive alanine scanning mutagenesis of the C-terminus we identify K250, K255, and E258 as the key residues for the formation of filopodia by Gpm6a. Substitution of these charged residues with alanine also diminishes the amount of Gpm6a on cell surface and in case of K255 and E258 leads to the lower amount of total expressed protein. Subsequent bioinformatic analysis of Gpm6a amino acid sequence reveals that highly conserved and functional residues cluster preferentially within the C- and not within the N-terminus and that K250, K255, and E258 are predicted as part of sorting signals of transmembrane proteins. Altogether, our results provide evidence that filopodium outgrowth induced by Gpm6a requires functionally critical residues within the C-terminal cytoplasmic tail.
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Affiliation(s)
- Nicolás M Rosas
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, CONICET-UNSAM, San Martin, Argentina
| | - Anabel Alvarez Juliá
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, CONICET-UNSAM, San Martin, Argentina
| | - Sofia E Alzuri
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, CONICET-UNSAM, San Martin, Argentina
| | - Alberto C Frasch
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, CONICET-UNSAM, San Martin, Argentina
| | - Beata Fuchsova
- Instituto de Investigaciones Biotecnológicas IIB-INTECH, CONICET-UNSAM, San Martin, Argentina
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Mutations in the Drosophila tricellular junction protein M6 synergize with RasV12 to induce apical cell delamination and invasion. Proc Natl Acad Sci U S A 2018; 115:8358-8363. [PMID: 30061406 DOI: 10.1073/pnas.1807343115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Complications from metastasis are responsible for the majority of cancer-related deaths. Despite the outsized medical impact of metastasis, remarkably little is known about one of the key early steps of metastasis: departure of a tumor cell from its originating tissue. It is well documented that cellular delamination in the basal direction can induce invasive behaviors, but it remains unknown if apical cell delamination can induce migration and invasion in a cancer context. To explore this feature of cancer progression, we performed a genetic screen in Drosophila and discovered that mutations in the protein M6 synergize with oncogenic Ras to drive invasion following apical delamination without crossing a basement membrane. Mechanistically, we observed that M6-deficient RasV12 clones delaminate as a result of alterations in a Canoe-RhoA-myosin II axis that is necessary for both the delamination and invasion phenotypes. To uncover the cellular roles of M6, we show that it localizes to tricellular junctions in epithelial tissues where it is necessary for the structural integrity of multicellular contacts. This work provides evidence that apical delamination can precede invasion and highlights the important role that tricellular junction integrity can play in this process.
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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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8
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Fuchsova B, Alvarez Juliá A, Rizavi HS, Frasch AC, Pandey GN. Altered expression of neuroplasticity-related genes in the brain of depressed suicides. Neuroscience 2015; 299:1-17. [PMID: 25934039 DOI: 10.1016/j.neuroscience.2015.04.057] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/02/2015] [Accepted: 04/22/2015] [Indexed: 02/04/2023]
Abstract
BACKGROUND Expression of the neuronal membrane glycoprotein M6a (GPM6A), the proteolipid protein (PLP/DM20) family member, is downregulated in the hippocampus of chronically stressed animals. Its neuroplastic function involves a role in neurite formation, filopodium outgrowth and synaptogenesis through an unknown mechanism. Disruptions in neuroplasticity mechanisms have been shown to play a significant part in the etiology of depression. Thus, the current investigation examined whether GPM6A expression is also altered in human depressed brain. METHODS Expression levels and coexpression patterns of GPM6A, GPM6B, and PLP1 (two other members of PLP/DM20 family) as well as of the neuroplasticity-related genes identified to associate with GPM6A were determined using quantitative polymerase chain reaction (qPCR) in postmortem samples from the hippocampus (n = 18) and the prefrontal cortex (PFC) (n = 25) of depressed suicide victims and compared with control subjects (hippocampus n = 18; PFC n = 25). Neuroplasticity-related proteins that form complexes with GPM6A were identified by coimmunoprecipitation technique followed by mass spectrometry. RESULTS Results indicated transcriptional downregulation of GPM6A and GPM6B in the hippocampus of depressed suicides. The expression level of calcium/calmodulin-dependent protein kinase II alpha (CAMK2A) and coronin1A (CORO1A) was also significantly decreased. Subsequent analysis of coexpression patterns demonstrated coordinated gene expression in the hippocampus and in the PFC indicating that the function of these genes might be coregulated in the human brain. However, in the brain of depressed suicides this coordinated response was disrupted. CONCLUSIONS Disruption of coordinated gene expression as well as abnormalities in GPM6A and GPM6B expression and expression of the components of GPM6A complexes were detected in the brain of depressed suicides.
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Affiliation(s)
- B Fuchsova
- Instituto de Investigaciones Biotecnológicas, CONICET-UNSAM, 1650 San Martin, Argentina.
| | - A Alvarez Juliá
- Instituto de Investigaciones Biotecnológicas, CONICET-UNSAM, 1650 San Martin, Argentina
| | - H S Rizavi
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - A C Frasch
- Instituto de Investigaciones Biotecnológicas, CONICET-UNSAM, 1650 San Martin, Argentina
| | - G N Pandey
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA
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Lázaro-Martínez JM, Rodríguez-Castellón E, Vega D, Monti GA, Chattah AK. Solid-state Studies of the Crystalline/Amorphous Character in Linear Poly(ethylenimine hydrochloride) (PEI·HCl) Polymers and Their Copper Complexes. Macromolecules 2015. [DOI: 10.1021/ma5023082] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juan Manuel Lázaro-Martínez
- CONICET, Av. Rivadavia 1917 (C1033AAJ), CABA, Argentina
- Departamento
de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 (C1113AAD), CABA, Argentina
| | - Enrique Rodríguez-Castellón
- Departamento
de Química Inorgánica, Cristalografía y Mineralogía,
Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, Málaga, 29071, Spain
| | - Daniel Vega
- Departamento
de Física de la Materia Condensada, Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, 1650 San Martín, Buenos
Aires, Argentina
- Escuela de
Ciencia y Tecnología, Universidad Nacional de General San Martín, Buenos Aires, Argentina
| | - Gustavo Alberto Monti
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET, Medina Allende s/n (X5000HUA), Córdoba, Argentina
| | - Ana Karina Chattah
- FaMAF-Universidad Nacional de Córdoba and IFEG-CONICET, Medina Allende s/n (X5000HUA), Córdoba, Argentina
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Mita S, de Monasterio-Schrader P, Fünfschilling U, Kawasaki T, Mizuno H, Iwasato T, Nave KA, Werner HB, Hirata T. Transcallosal Projections Require Glycoprotein M6-Dependent Neurite Growth and Guidance. Cereb Cortex 2014; 25:4111-25. [PMID: 24917275 DOI: 10.1093/cercor/bhu129] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The function of mature neurons critically relies on the developmental outgrowth and projection of their cellular processes. It has long been postulated that the neuronal glycoproteins M6a and M6b are involved in axon growth because these four-transmembrane domain-proteins of the proteolipid protein family are highly enriched on growth cones, but in vivo evidence has been lacking. Here, we report that the function of M6 proteins is required for normal axonal extension and guidance in vivo. In mice lacking both M6a and M6b, a severe hypoplasia of axon tracts was manifested. Most strikingly, the corpus callosum was reduced in thickness despite normal densities of cortical projection neurons. In single neuron tracing, many axons appeared shorter and disorganized in the double-mutant cortex, and some of them were even misdirected laterally toward the subcortex. Probst bundles were not observed. Upon culturing, double-mutant cortical and cerebellar neurons displayed impaired neurite outgrowth, indicating a cell-intrinsic function of M6 proteins. A rescue experiment showed that the intracellular loop of M6a is essential for the support of neurite extension. We propose that M6 proteins are required for proper extension and guidance of callosal axons that follow one of the most complex trajectories in the mammalian nervous system.
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Affiliation(s)
- Sakura Mita
- Division of Brain Function, National Institute of Genetics, Graduate University for Advanced Studies (Sokendai), Mishima 411-8540, Japan
| | | | - Ursula Fünfschilling
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Goettingen, Germany
| | - Takahiko Kawasaki
- Division of Brain Function, National Institute of Genetics, Graduate University for Advanced Studies (Sokendai), Mishima 411-8540, Japan
| | - Hidenobu Mizuno
- Division of Neurogenetics, National Institute of Genetics, Graduate University for Advanced Studies (Sokendai), Mishima 411-8540, Japan
| | - Takuji Iwasato
- Division of Neurogenetics, National Institute of Genetics, Graduate University for Advanced Studies (Sokendai), Mishima 411-8540, Japan
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Goettingen, Germany
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, D-37075 Goettingen, Germany
| | - Tatsumi Hirata
- Division of Brain Function, National Institute of Genetics, Graduate University for Advanced Studies (Sokendai), Mishima 411-8540, Japan
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