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Yao Y, Qiu L, Wei X, Chen J, Choy KW, Zheng G, Yang T, Li S, Yang F. Functional study of a rare L1CAM gene c.1759G>C variant prove its pathogenicity. Cell Biochem Funct 2024; 42:e4034. [PMID: 38715189 DOI: 10.1002/cbf.4034] [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: 03/09/2024] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 05/14/2024]
Abstract
L1 syndrome, a neurological disorder with an X-linked inheritance pattern, mainly results from mutations occurring in the L1 cell adhesion molecule (L1CAM) gene. The L1CAM molecule, belonging to the immunoglobulin (Ig) superfamily of neurocyte adhesion molecules, plays a pivotal role in facilitating intercellular signal transmission across membranes and is indispensable for proper neuronal development and function. This study identified a rare missense variant (c.1759G>C; p.G587R) in the L1CAM gene within a male fetus presenting with hydrocephalus. Due to a lack of functional analysis, the significance of the L1CAM mutation c.1759G>C (p.G587R) remains unknown. We aimed to perform further verification for its pathogenicity. Blood samples were obtained from the proband and his parents for trio clinical exome sequencing and mutation analysis. Expression level analysis was conducted using western blot techniques. Immunofluorescence was employed to investigate L1CAM subcellular localization, while cell aggregation and cell scratch assays were utilized to assess protein function. The study showed that the mutation (c.1759G>C; p.G587R) affected posttranslational glycosylation modification and induced alterations in the subcellular localization of L1-G587R in the cells. It resulted in the diminished expression of L1CAM on the cell surface and accumulation in the endoplasmic reticulum. The p.G587R altered the function of L1CAM protein and reduced homophilic adhesion capacity of proteins, leading to impaired adhesion and migration of proteins between cells. Our findings provide first biological evidence for the association between the missense mutation (c.1759G>c; p.G587R) in the L1CAM gene and L1 syndrome, confirming the pathogenicity of this missense mutation.
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Affiliation(s)
- Yuqing Yao
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Liyan Qiu
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Xingyu Wei
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jianping Chen
- Medical Equipment Department, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Kwong Wai Choy
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong SAR, China
- Laboratory of Genetics and Genomics, Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Guiyun Zheng
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Tuyin Yang
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Sisi Li
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Fang Yang
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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Wang P, Liao H, Wang Q, Xie H, Wang H, Yang M, Liu S. L1 Syndrome Prenatal Diagnosis Supplemented by Functional Analysis of One L1CAM Gene Missense Variant. Reprod Sci 2021; 29:768-780. [PMID: 34914080 PMCID: PMC8863719 DOI: 10.1007/s43032-021-00828-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/06/2021] [Indexed: 11/30/2022]
Abstract
L1 syndrome, a complex X-linked neurological disorder, is caused by mutations in the L1 cell adhesion molecule (L1CAM) gene. L1CAM molecule is a member of immunoglobulin (Ig) superfamily of neural cell adhesion molecules (CAMs), which plays a pivotal role in the developing nervous system. In this study, a L1CAM gene exonic missense variant (c.1108G > A, p.G370R) was identified in two induced fetuses (abnormal fetuses), who presented corpus callosum agenesis accompanied with hydrocephalus. Clinical data, published literature, online database, and bioinformatic analysis suggest that the single-nucleotide variant of L1CAM gene is a likely pathogenic mutation. In vitro assays were performed to evaluate the effects of this variant. Based on NSC-34/COS-7 cells transfected with wild-type (L1-WT) and mutated (L1-G370R) plasmids, the L1CAM gene exonic missense variant (c.1108G > A, p.G370R) reduced cell surface expression, induced partial endoplasmic reticulum retention, affected posttranslational modification, and reduced protein’s homophilic adhesive ability, but did not induce endoplasmic reticulum stress, which might probably associate with L1 syndrome. Finally, 35 isolated fetuses were screened for L1CAM gene variants by Sanger sequencing. These cases all prenatally suspected of corpus callosum agenesis accompanied with hydrocephalus, which may relate to L1 syndrome. Consequently, one L1CAM gene single missense variant (c.550C > T, p.R184W) was detected in one fetus. Our results provided evidence that the L1CAM gene missense variant (c.1108G > A, p.G370R) may relate to L1 syndrome. The findings of this study suggest a potential possibility of L1CAM gene screening for prenatal diagnoses for fetuses presented corpus callosum agenesis accompanied with hydrocephalus.
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Affiliation(s)
- Ping Wang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Hong Liao
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Quyou Wang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Hanbing Xie
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - He Wang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Mei Yang
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China
| | - Shanling Liu
- Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, No. 20, Section 3, Renminnan Road, Chengdu, 610041, Sichuan, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
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3
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Resnik-Docampo M, Cunningham KM, Ruvalcaba SM, Choi C, Sauer V, Jones DL. Neuroglian regulates Drosophila intestinal stem cell proliferation through enhanced signaling via the epidermal growth factor receptor. Stem Cell Reports 2021; 16:1584-1597. [PMID: 33961791 PMCID: PMC8190597 DOI: 10.1016/j.stemcr.2021.04.006] [Citation(s) in RCA: 3] [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: 09/20/2020] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 12/27/2022] Open
Abstract
The Drosophila intestine is an excellent system for elucidating mechanisms regulating stem cell behavior. Here we show that the septate junction (SJ) protein Neuroglian (Nrg) is expressed in intestinal stem cells (ISCs) and enteroblasts (EBs) within the fly intestine. SJs are not present between ISCs and EBs, suggesting Nrg plays a different role in this tissue. We reveal that Nrg is required for ISC proliferation in young flies, and depletion of Nrg from ISCs and EBs suppresses increased ISC proliferation in aged flies. Conversely, overexpression of Nrg in ISC and EBs promotes ISC proliferation, leading to an increase in cells expressing ISC/EB markers; in addition, we observe an increase in epidermal growth factor receptor (Egfr) activation. Genetic epistasis experiments reveal that Nrg acts upstream of Egfr to regulate ISC proliferation. As Nrg function is highly conserved in mammalian systems, our work characterizing the role of Nrg in the intestine has implications for the treatment of intestinal disorders that arise due to altered ISC behavior.
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Affiliation(s)
- Martin Resnik-Docampo
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kathleen M Cunningham
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - S Mateo Ruvalcaba
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Charles Choi
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Vivien Sauer
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - D Leanne Jones
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Giordano M, Cavallaro U. Different Shades of L1CAM in the Pathophysiology of Cancer Stem Cells. J Clin Med 2020; 9:E1502. [PMID: 32429448 PMCID: PMC7291284 DOI: 10.3390/jcm9051502] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/07/2020] [Accepted: 05/13/2020] [Indexed: 12/12/2022] Open
Abstract
L1 cell adhesion molecule (L1CAM) is aberrantly expressed in several tumor types where it is causally linked to malignancy and therapy resistance, acting also as a poor prognosis factor. Accordingly, several approaches have been developed to interfere with L1CAM function or to deliver cytotoxic agents to L1CAM-expressing tumors. Metastatic dissemination, tumor relapse and drug resistance can be fueled by a subpopulation of neoplastic cells endowed with peculiar biological properties that include self-renewal, efficient DNA repair, drug efflux machineries, quiescence, and immune evasion. These cells, known as cancer stem cells (CSC) or tumor-initiating cells, represent, therefore, an ideal target for tumor eradication. However, the molecular and functional traits of CSC have been unveiled only to a limited extent. In this context, it appears that L1CAM is expressed in the CSC compartment of certain tumors, where it plays a causal role in stemness itself and/or in biological processes intimately associated with CSC (e.g., epithelial-mesenchymal transition (EMT) and chemoresistance). This review summarizes the role of L1CAM in cancer focusing on its functional contribution to CSC pathophysiology. We also discuss the clinical usefulness of therapeutic strategies aimed at targeting L1CAM in the context of anti-CSC treatments.
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Affiliation(s)
| | - Ugo Cavallaro
- Unit of Gynaecological Oncology Research, European Institute of Oncology IRCSS, 20128 Milan, Italy;
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Samatov TR, Wicklein D, Tonevitsky AG. L1CAM: Cell adhesion and more. ACTA ACUST UNITED AC 2016; 51:25-32. [DOI: 10.1016/j.proghi.2016.05.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/20/2016] [Indexed: 12/17/2022]
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Christaller WAA, Vos Y, Gebre-Medhin S, Hofstra RMW, Schäfer MKE. L1 syndrome diagnosis complemented with functional analysis of L1CAM variants located to the two N-terminal Ig-like domains. Clin Genet 2016; 91:115-120. [DOI: 10.1111/cge.12763] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 02/15/2016] [Accepted: 02/15/2016] [Indexed: 11/30/2022]
Affiliation(s)
- W. A. A. Christaller
- Department of Anesthesiology, University Medical Center; Johannes Gutenberg-University Mainz; Mainz Germany
| | - Y. Vos
- Department of Genetics, University Medical Centre Groningen; University of Groningen; Groningen The Netherlands
| | - S. Gebre-Medhin
- Department of Clinical Genetics; University Hospital, Lund University; Lund Sweden
| | - R. M. W. Hofstra
- Department of Clinical Genetics; University of Rotterdam; Rotterdam The Netherlands
| | - M. K. E. Schäfer
- Department of Anesthesiology, University Medical Center; Johannes Gutenberg-University Mainz; Mainz Germany
- Focus program Translational Neurosciences (FTN); Johannes Gutenberg-University Mainz; Mainz Germany
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7
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Melo US, Macedo-Souza LI, Figueiredo T, Muotri AR, Gleeson JG, Coux G, Armas P, Calcaterra NB, Kitajima JP, Amorim S, Olávio TR, Griesi-Oliveira K, Coatti GC, Rocha CRR, Martins-Pinheiro M, Menck CFM, Zaki MS, Kok F, Zatz M, Santos S. Overexpression of KLC2 due to a homozygous deletion in the non-coding region causes SPOAN syndrome. Hum Mol Genet 2015; 24:6877-85. [PMID: 26385635 DOI: 10.1093/hmg/ddv388] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 09/14/2015] [Indexed: 02/06/2023] Open
Abstract
SPOAN syndrome is a neurodegenerative disorder mainly characterized by spastic paraplegia, optic atrophy and neuropathy (SPOAN). Affected patients are wheelchair bound after 15 years old, with progressive joint contractures and spine deformities. SPOAN patients also have sub normal vision secondary to apparently non-progressive congenital optic atrophy. A potential causative gene was mapped at 11q13 ten years ago. Here we performed next-generation sequencing in SPOAN-derived samples. While whole-exome sequencing failed to identify the causative mutation, whole-genome sequencing allowed to detect a homozygous 216-bp deletion (chr11.hg19:g.66,024,557_66,024,773del) located at the non-coding upstream region of the KLC2 gene. Expression assays performed with patient's fibroblasts and motor neurons derived from SPOAN patients showed KLC2 overexpression. Luciferase assay in constructs with 216-bp deletion confirmed the overexpression of gene reporter, varying from 48 to 74%, as compared with wild-type. Knockdown and overexpression of klc2 in Danio rerio revealed mild to severe curly-tail phenotype, which is suggestive of a neuromuscular disorder. Overexpression of a gene caused by a small deletion in the non-coding region is a novel mechanism, which to the best of our knowledge, was never reported before in a recessive condition. Although the molecular mechanism of KLC2 up-regulation still remains to be uncovered, such example adds to the importance of non-coding regions in human pathology.
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Affiliation(s)
- Uirá S Melo
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil
| | - Lucia I Macedo-Souza
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil
| | - Thalita Figueiredo
- Northeast Biotechnology Network (RENORBIO), Federal University of Paraiba (UFPB), Joao Pessoa, PB 58051-900, Brazil, Department of Biology, Paraiba State University (UEPB), Campina Grande, PB 58429-500, Brazil
| | - Alysson R Muotri
- Department of Pediatrics/Rady Children's Hospital San Diego, University of California San Diego, La Jolla, CA 92093, USA
| | - Joseph G Gleeson
- Laboratory for Pediatric Brain Disease, The Rockefeller University, New York, NY 10065, USA
| | - Gabriela Coux
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, SF S2002LRK, Argentina
| | - Pablo Armas
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, SF S2002LRK, Argentina
| | - Nora B Calcaterra
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Rosario, SF S2002LRK, Argentina
| | | | - Simone Amorim
- Department of Neurology, School of Medicine, University of Sao Paulo (USP), São Paulo, SP 01246-903, Brazil
| | - Thiago R Olávio
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil
| | - Karina Griesi-Oliveira
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil
| | - Giuliana C Coatti
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil
| | - Clarissa R R Rocha
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP 05508-900, Brazil and
| | - Marinalva Martins-Pinheiro
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP 05508-900, Brazil and
| | - Carlos F M Menck
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, SP 05508-900, Brazil and
| | - Maha S Zaki
- Department of Clinical Genetics, Human Genetics and Genome Research Division, National Research Center, Cairo 12311, Egypt
| | - Fernando Kok
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil, Mendelics Genomic Analysis, São Paulo, SP 04013-000, Brazil
| | - Mayana Zatz
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Biosciences Institute, University of Sao Paulo (USP), Sao Paulo, SP 05508-090, Brazil,
| | - Silvana Santos
- Northeast Biotechnology Network (RENORBIO), Federal University of Paraiba (UFPB), Joao Pessoa, PB 58051-900, Brazil, Department of Biology, Paraiba State University (UEPB), Campina Grande, PB 58429-500, Brazil
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Matzat T, Sieglitz F, Kottmeier R, Babatz F, Engelen D, Klämbt C. Axonal wrapping in the Drosophila PNS is controlled by glia-derived neuregulin homolog Vein. Development 2015; 142:1336-45. [PMID: 25758464 DOI: 10.1242/dev.116616] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Efficient neuronal conductance requires that axons are insulated by glial cells. For this, glial membranes need to wrap around axons. Invertebrates show a relatively simple extension of glial membranes around the axons, resembling Remak fibers formed by Schwann cells in the mammalian peripheral nervous system. To unravel the molecular pathways underlying differentiation of glial cells that provide axonal wrapping, we are using the genetically amenable Drosophila model. At the end of larval life, the wrapping glia differentiates into very large cells, spanning more than 1 mm of axonal length. The extension around axonal membranes is not influenced by the caliber of the axon or its modality. Using cell type-specific gene knockdown we show that the extension of glial membranes around the axons is regulated by an autocrine activation of the EGF receptor through the neuregulin homolog Vein. This resembles the molecular mechanism employed during cell-autonomous reactivation of glial differentiation after injury in mammals. We further demonstrate that Vein, produced by the wrapping glia, also regulates the formation of septate junctions in the abutting subperineurial glia. Moreover, the wrapping glia indirectly controls the proliferation of the perineurial glia. Thus, the wrapping glia appears center stage to orchestrate the development of the different glial cell layers in a peripheral nerve.
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Affiliation(s)
- Till Matzat
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
| | - Florian Sieglitz
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
| | - Rita Kottmeier
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
| | - Felix Babatz
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
| | - Daniel Engelen
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
| | - Christian Klämbt
- Institut für Neurobiologie, Universität Münster, Badestr. 9, Münster D-48149, Germany
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Nagaraj K, Mualla R, Hortsch M. The L1 Family of Cell Adhesion Molecules: A Sickening Number of Mutations and Protein Functions. ADVANCES IN NEUROBIOLOGY 2014; 8:195-229. [DOI: 10.1007/978-1-4614-8090-7_9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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10
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Differential effects of human L1CAM mutations on complementing guidance and synaptic defects in Drosophila melanogaster. PLoS One 2013; 8:e76974. [PMID: 24155914 PMCID: PMC3796554 DOI: 10.1371/journal.pone.0076974] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 09/05/2013] [Indexed: 01/17/2023] Open
Abstract
A large number of different pathological L1CAM mutations have been identified that result in a broad spectrum of neurological and non-neurological phenotypes. While many of these mutations have been characterized for their effects on homophilic and heterophilic interactions, as well as expression levels in vitro, there are only few studies on their biological consequences in vivo. The single L1-type CAM gene in Drosophila, neuroglian (nrg), has distinct functions during axon guidance and synapse formation and the phenotypes of nrg mutants can be rescued by the expression of human L1CAM. We previously showed that the highly conserved intracellular FIGQY Ankyrin-binding motif is required for L1CAM-mediated synapse formation, but not for neurite outgrowth or axon guidance of the Drosophila giant fiber (GF) neuron. Here, we use the GF as a model neuron to characterize the pathogenic L120V, Y1070C, C264Y, H210Q, E309K and R184Q extracellular L1CAM missense mutations and a L1CAM protein with a disrupted ezrin-moesin-radixin (ERM) binding site to investigate the signaling requirements for neuronal development. We report that different L1CAM mutations have distinct effects on axon guidance and synapse formation. Furthermore, L1CAM homophilic binding and signaling via the ERM motif is essential for axon guidance in Drosophila. In addition, the human pathological H210Q, R184Q and Y1070C, but not the E309K and L120V L1CAM mutations affect outside-in signaling via the FIGQY Ankyrin binding domain which is required for synapse formation. Thus, the pathological phenotypes observed in humans are likely to be caused by the disruption of signaling required for both, guidance and synaptogenesis.
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Abstract
Homophilic interaction of the L1 family of cell adhesion molecules plays a pivotal role in regulating neurite outgrowth and neural cell networking in vivo. Functional defects in L1 family members are associated with neurological disorders such as X-linked mental retardation, multiple sclerosis, low-IQ syndrome, developmental delay, and schizophrenia. Various human tumors with poor prognosis also implicate the role of L1, a representative member of the L1 family of cell adhesion molecules, and ectopic expression of L1 in fibroblastic cells induces metastasis-associated gene expression. Previous studies on L1 homologs indicated that four N-terminal immunoglobulin-like domains form a horseshoe-like structure that mediates homophilic interactions. Various models including the zipper, domain-swap, and symmetry-related models are proposed to be involved in structural mechanism of homophilic interaction of the L1 family members. Recently, cryo-electron tomography of L1 and crystal structure studies of neurofascin, an L1 family protein, have been performed. This review focuses on recent discoveries of different models and describes the possible structural mechanisms of homophilic interactions of L1 family members. Understanding structural mechanisms of homophilic interactions in various cell adhesion proteins should aid the development of therapeutic strategies for L1 family cell adhesion molecule-associated diseases.
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Affiliation(s)
- Chun Hua Wei
- Department of Bioengineering, College of Engineering, Hanyang University, Seoul 133-791, Korea
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12
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Tagliavacca L, Colombo F, Racchetti G, Meldolesi J. L1CAM and its cell-surface mutants: new mechanisms and effects relevant to the physiology and pathology of neural cells. J Neurochem 2012; 124:397-409. [PMID: 22973895 PMCID: PMC3557714 DOI: 10.1111/jnc.12015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/05/2012] [Accepted: 09/08/2012] [Indexed: 11/27/2022]
Abstract
The L1 syndrome, a genetic disease that affects 1/30 000 newborn males, is sustained by numerous missense mutations of L1 cell adhesion molecule (L1CAM), an adhesion surface protein active also in transmembrane signaling, essential for the development and function of neurons. To investigate the cell biology of L1CAM, we employed a high RE1-silencing transcription (factor) clone of the pheochromocytoma PC12 line, defective in L1CAM expression and neurite outgrowth. The clone was transfected with wild-type L1CAM and four missense, disease-inducing point mutants encoding proteins distributed to the cell surface. The mutant-expressing cells, defective in adhesion to extracellular matrix proteins and in migration, exhibited unchanged proliferation. The nerve growth factor (NGF)-induced neurite outgrowth was re-established in defective clone cells transfected with the wild-type and the H210Q and I219T L1CAMs mutants, but not in the others. The stimulated outgrowth was confirmed in a second defective PC12 clone over-expressing the NGF receptor TrkA, treated with NGF and/or a recombinant L1CAM chimera. These results revealed a new function of L1CAM, a positive, robust and dose-dependent modulation of the TrkA receptor activated spontaneously or by NGF. The variable effects observed with the different L1CAM mutants suggest that this function contributes to the marked heterogeneity of symptoms and severity observed in the patients affected by the L1 syndrome.
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Affiliation(s)
- Luigina Tagliavacca
- Department of Neuroscience, Vita-Salute San Raffaele University and San Raffaele Institute, Milano, Italy
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Donier E, Gomez-Sanchez JA, Grijota-Martinez C, Lakomá J, Baars S, Garcia-Alonso L, Cabedo H. L1CAM binds ErbB receptors through Ig-like domains coupling cell adhesion and neuregulin signalling. PLoS One 2012; 7:e40674. [PMID: 22815787 PMCID: PMC3398014 DOI: 10.1371/journal.pone.0040674] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 06/12/2012] [Indexed: 01/14/2023] Open
Abstract
During nervous system development different cell-to-cell communication mechanisms operate in parallel guiding migrating neurons and growing axons to generate complex arrays of neural circuits. How such a system works in coordination is not well understood. Cross-regulatory interactions between different signalling pathways and redundancy between them can increase precision and fidelity of guidance systems. Immunoglobulin superfamily proteins of the NCAM and L1 families couple specific substrate recognition and cell adhesion with the activation of receptor tyrosine kinases. Thus it has been shown that L1CAM-mediated cell adhesion promotes the activation of the EGFR (erbB1) from Drosophila to humans. Here we explore the specificity of the molecular interaction between L1CAM and the erbB receptor family. We show that L1CAM binds physically erbB receptors in both heterologous systems and the mammalian developing brain. Different Ig-like domains located in the extracellular part of L1CAM can support this interaction. Interestingly, binding of L1CAM to erbB enhances its response to neuregulins. During development this may synergize with the activation of erbB receptors through L1CAM homophilic interactions, conferring diffusible neuregulins specificity for cells or axons that interact with the substrate through L1CAM.
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Affiliation(s)
- Emanuelle Donier
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
| | - Jose Antonio Gomez-Sanchez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
- Fundación de la Comunidad Valenciana para la Investigación en el Hospital General Universitario de Alicante, Alicante, Spain
| | - Carmen Grijota-Martinez
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
| | - Jarmila Lakomá
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
| | - Sigrid Baars
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
| | - Luis Garcia-Alonso
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
- * E-mail: (LGA); (HC)
| | - Hugo Cabedo
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Spanish National Research Council, San Juan de Alicante, Spain
- Fundación de la Comunidad Valenciana para la Investigación en el Hospital General Universitario de Alicante, Alicante, Spain
- * E-mail: (LGA); (HC)
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14
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Marx M, Diestel S, Bozon M, Keglowich L, Drouot N, Bouché E, Frebourg T, Minz M, Saugier-Veber P, Castellani V, Schäfer MKE. Pathomechanistic characterization of two exonic L1CAM variants located in trans in an obligate carrier of X-linked hydrocephalus. Neurogenetics 2012; 13:49-59. [PMID: 22222883 DOI: 10.1007/s10048-011-0307-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 12/07/2011] [Indexed: 11/29/2022]
Abstract
Mutations in the gene encoding the neural cell adhesion molecule L1CAM cause several neurological disorders collectively referred to as L1 syndrome. We report here a family case of X-linked hydrocephalus in which an obligate female carrier has two exonic L1CAM missense mutations in trans substituting amino acids in the first (p.W635C) or second (p.V768I) fibronectin-type III domains. We performed various biochemical and cell biological in vitro assays to evaluate the pathogenicity of these variants. Mutant L1-W635C protein accumulates in the endoplasmic reticulum (ER), is not transported into axons, and fails to promote L1CAM-mediated cell-cell adhesion as well as neurite growth. Immunoprecipitation experiments show that L1-W635C associates with the molecular ER chaperone calnexin and is modified by poly-ubiquitination. The mutant L1-V768I protein localizes at the cell surface, is not retained in the ER, and promotes neurite growth similar to wild-type L1CAM. However, the p.V768I mutation impairs L1CAM-mediated cell-cell adhesion albeit less severe than L1-W635C. These data indicate that p.W635C is a novel loss-of-function L1 syndrome mutation. The p.V768I mutation may represent a non-pathogenic variant or a variant associated with low penetrance. The poly-ubiquitination of L1-W635C and its association with the ER chaperone calnexin provide further insights into the molecular mechanisms underlying defective cell surface trafficking of L1CAM in L1 syndrome.
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Affiliation(s)
- Mariola Marx
- Institute of Anatomy and Cell Biology, Center for Neurosciences, University of Freiburg, Freiburg, Germany
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15
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Adhesion and signaling between neurons and glial cells in Drosophila. Curr Opin Neurobiol 2011; 21:11-6. [DOI: 10.1016/j.conb.2010.08.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/03/2010] [Accepted: 08/15/2010] [Indexed: 12/21/2022]
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16
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Linking L1CAM-mediated signaling to NF-κB activation. Trends Mol Med 2010; 17:178-87. [PMID: 21195665 DOI: 10.1016/j.molmed.2010.11.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/19/2010] [Accepted: 11/19/2010] [Indexed: 01/13/2023]
Abstract
The cell adhesion molecule L1 (L1CAM) was originally identified as a neural adhesion molecule essential for neurite outgrowth and axon guidance. Many studies have now shown that L1CAM is overexpressed in human carcinomas and associated with poor prognosis. So far, L1CAM-mediated cellular signaling has been largely attributed to an association with growth factor receptors, referred to as L1CAM-'assisted' signaling. New data demonstrate that L1CAM can signal via two additional mechanisms: 'forward' signaling via regulated intramembrane proteolysis and 'reverse' signaling via the activation of the transcription factor nuclear factor (NF)-κB. Taken together, these findings lead to a new understanding of L1CAM downstream signaling that is fundamental for the development of anti-L1CAM antibody-mediated therapeutics in human tumor cells.
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17
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Schäfer MKE, Altevogt P. L1CAM malfunction in the nervous system and human carcinomas. Cell Mol Life Sci 2010; 67:2425-37. [PMID: 20237819 PMCID: PMC11115577 DOI: 10.1007/s00018-010-0339-1] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/30/2010] [Accepted: 02/11/2010] [Indexed: 12/14/2022]
Abstract
Research over the last 25 years on the cell adhesion molecule L1 has revealed its pivotal role in nervous system function. Mutations of the human L1CAM gene have been shown to cause neurodevelopmental disorders such as X-linked hydrocephalus, spastic paraplegia and mental retardation. Impaired L1 function has been also implicated in the aetiology of fetal alcohol spectrum disorders, defective enteric nervous system development and malformations of the renal system. Importantly, aberrant expression of L1 has emerged as a critical factor in the development of human carcinomas, where it enhances cell proliferation, motility and chemoresistance. This discovery promoted collaborative work between tumour biologists and neurobiologists, which has led to a substantial expansion of the basic knowledge about L1 function and regulation. Here we provide an overview of the pathological conditions caused by L1 malfunction. We further discuss how the available data on gene regulation, molecular interactions and posttranslational processing of L1 may contribute to a better understanding of associated neurological and cancerous diseases.
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Affiliation(s)
- Michael K E Schäfer
- Center for Neurosciences, Institute of Anatomy and Cell Biology, University of Freiburg, Freiburg, Germany.
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18
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L1 syndrome mutations impair neuronal L1 function at different levels by divergent mechanisms. Neurobiol Dis 2010; 40:222-37. [PMID: 20621658 DOI: 10.1016/j.nbd.2010.05.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 05/19/2010] [Accepted: 05/25/2010] [Indexed: 11/22/2022] Open
Abstract
Mutations in the human L1CAM gene cause neurodevelopmental disorders collectively referred to as L1 syndrome. Here, we investigated cellular pathomechanisms underlying two L1 syndrome mutations, R184Q and W1036L. We demonstrate that these mutations cause partial endoplasmic reticulum (ER) retention of L1, reduce L1 cell surface expression, but do not induce ER stress in neuronal NSC-34 cells. We provide evidence that surface trafficking of mutated L1 is affected by defective sorting to ER exit sites and attenuated ER export. However, in differentiated neuronal cultures and long-term cultured hippocampal slices, the L1-R184Q protein is restricted to cell bodies, whereas L1-W1036L also aberrantly localizes to dendrites. These trafficking defects preclude axonal targeting of L1, thereby affecting L1-mediated axon growth and arborization. Our results indicate that L1 syndrome mutations impair neuronal L1 function at different levels, firstly by attenuating ER export and secondly by interfering with polarized neuronal trafficking.
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