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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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Alvarez Juliá A, Frasch AC, Fuchsova B. Neuronal filopodium formation induced by the membrane glycoprotein M6a (Gpm6a) is facilitated by coronin-1a, Rac1, and p21-activated kinase 1 (Pak1). J Neurochem 2016; 137:46-61. [PMID: 26809475 DOI: 10.1111/jnc.13552] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 01/01/2023]
Abstract
Stress-responsive neuronal membrane glycoprotein M6a (Gpm6a) functions in neurite extension, filopodium and spine formation and synaptogenesis. The mechanisms of Gpm6a action in these processes are incompletely understood. Previously, we identified the actin regulator coronin-1a (Coro1a) as a putative Gpm6a interacting partner. Here, we used co-immunoprecipitation assays with the anti-Coro1a antibody to show that Coro1a associates with Gpm6a in rat hippocampal neurons. By immunofluorescence microscopy, we demonstrated that in hippocampal neurons Coro1a localizes in F-actin-enriched regions and some of Coro1a spots co-localize with Gpm6a labeling. Notably, the over-expression of a dominant-negative form of Coro1a as well as its down-regulation by siRNA interfered with Gpm6a-induced filopodium formation. Coro1a is known to regulate the plasma membrane translocation and activation of small GTPase Rac1. We show that Coro1a co-immunoprecipitates with Rac1 together with Gpm6a. Pharmacological inhibition of Rac1 resulted in a significant decrease in filopodium formation by Gpm6a. The same was observed upon the co-expression of Gpm6a with the inactive GDP-bound form of Rac1. In this case, the elevated membrane recruitment of GDP-bound Rac1 was detected as well. Moreover, the kinase activity of the p21-activated kinase 1 (Pak1), a main downstream effector of Rac1 that acts downstream of Coro1a, was required for Gpm6a-induced filopodium formation. Taken together, our results provide evidence that a signaling pathway including Coro1a, Rac1, and Pak1 facilitates Gpm6a-induced filopodium formation. Formation of filopodia by membrane glycoprotein M6a (Gpm6a) requires actin regulator coronin-1a (Coro1a), known to regulate plasma membrane localization and activation of Rac1 and its downstream effector Pak1. Coro1a associates with Gpm6a. Blockage of Coro1a, Rac1, or Pak1 interferes with Gpm6a-induced filopodium formation. Moreover, Gpm6a facilitates Rac1 membrane recruitment. Altogether, a mechanistic insight into the process of Gpm6a-induced neuronal filopodium formation is provided.
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Affiliation(s)
- Anabel Alvarez Juliá
- 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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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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Formoso K, Billi SC, Frasch AC, Scorticati C. Tyrosine 251 at the C-terminus of neuronal glycoprotein M6a is critical for neurite outgrowth. J Neurosci Res 2014; 93:215-29. [PMID: 25242528 DOI: 10.1002/jnr.23482] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 07/12/2014] [Accepted: 08/15/2014] [Indexed: 12/12/2022]
Abstract
Neuronal glycoprotein M6a is involved in neuronal plasticity, promoting neurite and filopodia outgrowth and, likely, synaptogenesis. Polymorphisms in the human M6a gene GPM6A have recently been associated with mental illnesses such as schizophrenia, bipolar disorders, and claustrophobia. Nevertheless, the molecular bases underlying these observations remain unknown. We have previously documented that, to induce filopodia formation, M6a depends on the association of membrane lipid microdomains and the activation of Src and mitogen-activated protein kinase kinases. Here, in silico analysis of the phosphorylation of tyrosine 251 (Y251) at the C-terminus of M6a showed that it could be a target of Src kinases. We examined whether phosphorylation of M6a at Y251 affects neurite and filopodia outgrowth and the targets involved in its signal propagation. This work provides evidence that the Src kinase family and the phosphatidylinositide 3-kinase (PI3K), but not Ras, participate in M6a signal cascade leading to neurite/filopodia outgrowth in hippocampal neurons and murine neuroblastoma N2a cells. Phosphorylation of M6a at Y251 is essential only for neurite outgrowth by the PI3K/AKT-mediated pathway and, moreover, rescues the inhibition caused by selective Src inhibitor and external M6a monoclonal antibody treatment. Thus, we suggest that phosphorylation of M6a at Y251 is critical for a specific stage of neuronal development and triggers redundant signaling pathways leading to neurite extension.
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Affiliation(s)
- Karina Formoso
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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Identification of GPM6A and GPM6B as potential new human lymphoid leukemia-associated oncogenes. Cell Oncol (Dordr) 2014; 37:179-91. [PMID: 24916915 DOI: 10.1007/s13402-014-0171-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Previously, we found that the Graffi murine leukemia virus (MuLV) is able to induce a wide spectrum of hematologic malignancies in vivo. Using high-density oligonucleotide microarrays, we established the gene expression profiles of several of these malignancies, thereby specifically focusing on genes deregulated in the lymphoid sub-types. We observed over-expression of a variety of genes, including Arntl2, Bfsp2, Gfra2, Gpm6a, Gpm6b, Nln, Fbln1, Bmp7, Etv5 and Celsr1 and, in addition, provided evidence that Fmn2 and Parm-1 may act as novel oncogenes. In the present study, we assessed the expression patterns of eight selected human homologs of these genes in primary human B-cell malignancies, and explored the putative oncogenic potential of GPM6A and GPM6B. METHODS The gene expression levels of the selected human homologs were tested in human B-cell malignancies by semi-quantitative RT-PCR. The protein expression profiles of human GPM6A and GPM6B were analyzed by Western blotting. The localization and the effect of GPM6A and GPM6B on the cytoskeleton were determined using confocal and indirect immunofluorescence microscopy. To confirm the oncogenic potential of GPM6A and GPM6B, classical colony formation assays in soft agar and focus forming assays were used. The effects of these proteins on the cell cycle were assessed by flow cytometry analysis. RESULTS Using semi-quantitative RT-PCR, we found that most of the primary B-cell malignancies assessed showed altered expression patterns of the genes tested, including GPM6A and GPM6B. Using confocal microscopy, we found that the GPM6A protein (isoform 3) exhibits a punctate cytoplasmic localization and that the GPM6B protein (isoform 4) exhibits a peri-nuclear and punctate cytoplasmic localization. Interestingly, we found that exogenous over-expression of both proteins in NIH/3T3 cells alters the actin and microtubule networks and induces the formation of long filopodia-like protrusions. Additionally, we found that these over-expressing NIH/3T3 cells exhibit anchorage-independent growth and enhanced proliferation rates. Cellular transformation (i.e., loss of contact inhibition) was, however, only observed after exogenous over-expression of GPM6B. CONCLUSIONS Our results indicate that several human homologs of the genes found to be deregulated in Graffi MuLV experimental mouse models may serve as candidate biomarkers for human B-cell malignancies. In addition, we found that GPM6A and GPM6B may act as novel oncogenes in the development of these malignancies.
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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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Butland SL, Sanders SS, Schmidt ME, Riechers SP, Lin DTS, Martin DDO, Vaid K, Graham RK, Singaraja RR, Wanker EE, Conibear E, Hayden MR. The palmitoyl acyltransferase HIP14 shares a high proportion of interactors with huntingtin: implications for a role in the pathogenesis of Huntington's disease. Hum Mol Genet 2014; 23:4142-60. [PMID: 24705354 DOI: 10.1093/hmg/ddu137] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
HIP14 is the most highly conserved of 23 human palmitoyl acyltransferases (PATs) that catalyze the post-translational addition of palmitate to proteins, including huntingtin (HTT). HIP14 is dysfunctional in the presence of mutant HTT (mHTT), the causative gene for Huntington disease (HD), and we hypothesize that reduced palmitoylation of HTT and other HIP14 substrates contributes to the pathogenesis of the disease. Here we describe the yeast two-hybrid (Y2H) interactors of HIP14 in the first comprehensive study of interactors of a mammalian PAT. Unexpectedly, we discovered a highly significant overlap between HIP14 interactors and 370 published interactors of HTT, 4-fold greater than for control proteins (P = 8 × 10(-5)). Nearly half of the 36 shared interactors are already implicated in HD, supporting a direct link between HIP14 and the disease. The HIP14 Y2H interaction set is significantly enriched for palmitoylated proteins that are candidate substrates. We confirmed that three of them, GPM6A, and the Sprouty domain-containing proteins SPRED1 and SPRED3, are indeed palmitoylated by HIP14; the first enzyme known to palmitoylate these proteins. These novel substrates functions might be affected by reduced palmitoylation in HD. We also show that the vesicular cargo adapter optineurin, an established HTT-binding protein, co-immunoprecipitates with HIP14 but is not palmitoylated. mHTT leads to mislocalization of optineurin and aberrant cargo trafficking. Therefore, it is possible that optineurin regulates trafficking of HIP14 to its substrates. Taken together, our data raise the possibility that defective palmitoylation by HIP14 might be an important mechanism that contributes to the pathogenesis of HD.
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Affiliation(s)
- Stefanie L Butland
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Shaun S Sanders
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Mandi E Schmidt
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Sean-Patrick Riechers
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin-Buch 13125, Germany
| | - David T S Lin
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Dale D O Martin
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Kuljeet Vaid
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Rona K Graham
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Roshni R Singaraja
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Erich E Wanker
- Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin-Buch 13125, Germany
| | - Elizabeth Conibear
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4
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Zinc finger protein 219-like (ZNF219L) and Sox9a regulate synuclein-γ2 (sncgb) expression in the developing notochord of zebrafish. Biochem Biophys Res Commun 2013; 442:189-94. [DOI: 10.1016/j.bbrc.2013.11.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 11/09/2013] [Indexed: 11/24/2022]
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Lien HW, Yang CH, Cheng CH, Hung CC, Liao WH, Hwang PP, Han YS, Huang CJ. A novel zinc finger protein 219-like (ZNF219L) is involved in the regulation of collagen type 2 alpha 1a (col2a1a) gene expression in zebrafish notochord. Int J Biol Sci 2013; 9:872-86. [PMID: 24155663 PMCID: PMC3805895 DOI: 10.7150/ijbs.7126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/24/2013] [Indexed: 12/01/2022] Open
Abstract
The notochord is required for body plan patterning in vertebrates, and defects in notochord development during embryogenesis can lead to diseases affecting the adult. It is therefore important to elucidate the gene regulatory mechanism underlying notochord formation. In this study, we cloned the zebrafish zinc finger 219-like (ZNF219L) based on mammalian ZNF219, which contains nine C2H2-type zinc finger domains. Through whole-mount in situ hybridization, we found that znf219L mRNA is mainly expressed in the zebrafish midbrain-hindbrain boundary, hindbrain, and notochord during development. The znf219L morpholino knockdown caused partial abnormal notochord phenotype and reduced expression of endogenous col2a1a in the notochord specifically. In addition, ZNF219L could recognize binding sites with GGGGG motifs and trigger augmented activity of the col2a1a promoter in a luciferase assay. Furthermore, in vitro binding experiments revealed that ZNF219L recognizes the GGGGG motifs in the promoter region of the zebrafish col2a1a gene through its sixth and ninth zinc finger domains. Taken together, our results reveal that ZNF219L is involved in regulating the expression of col2a1a in zebrafish notochord specifically.
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Affiliation(s)
- Huang-Wei Lien
- 1. Institute of Fisheries Sciences, National Taiwan University, Taipei 106, Taiwan
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Bianchi C, Torsello B, Di Stefano V, Zipeto MA, Facchetti R, Bombelli S, Perego RA. One isoform of Arg/Abl2 tyrosine kinase is nuclear and the other seven cytosolic isoforms differently modulate cell morphology, motility and the cytoskeleton. Exp Cell Res 2013; 319:2091-2102. [PMID: 23707396 DOI: 10.1016/j.yexcr.2013.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/10/2013] [Accepted: 05/11/2013] [Indexed: 12/30/2022]
Abstract
The non-receptor tyrosine kinase Abelson related gene (Arg/Abl2) regulates cell migration and morphogenesis by modulating the cytoskeleton. Arg promotes actin-based cell protrusions and spreading, and inhibits cell migration by attenuating stress fiber formation and contractility via activation of the RhoA inhibitor, p190RhoGAP, and by regulating focal adhesion dynamics also via CrkII phosphorylation. Eight full-length Arg isoforms with different N- and C-termini are endogenously expressed in human cells. In this paper, the eight Arg isoforms, subcloned in the pFLAG-CMV2 vector, were transfected in COS-7 cells in order to study their subcellular distribution and role in cell morphology, migration and cytoskeletal modulation. The transfected 1BSCTS Arg isoform has a nuclear distribution and phosphorylates CrkII in the nucleus, whilst the other isoforms are detected in the cytoplasm. The 1BLCTL, 1BSCTL, 1ASCTS isoforms were able to significantly decrease stress fibers, induce cell shrinkage and filopodia-like protrusions with a significant increase in p190RhoGAP phosphorylation. In contrast, 1ALCTL, 1ALCTS, 1ASCTL and 1BLCTS isoforms do not significantly decrease stress fibers and induce the formation of retraction tail-like protrusions. The 1BLCTL and 1ALCTL isoforms have different effects on cell migration and focal adhesions. All these data may open new perspectives to study the mechanisms of cell invasiveness.
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Affiliation(s)
- Cristina Bianchi
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Barbara Torsello
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Vitalba Di Stefano
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Maria A Zipeto
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Rita Facchetti
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Silvia Bombelli
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy
| | - Roberto A Perego
- Department of Health Sciences, Milano-Bicocca University, 20900 Monza (MB), Italy.
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Cheng YC, Scotting PJ, Hsu LS, Lin SJ, Shih HY, Hsieh FY, Wu HL, Tsao CL, Shen CJ. Zebrafish rgs4 is essential for motility and axonogenesis mediated by Akt signaling. Cell Mol Life Sci 2013; 70:935-50. [PMID: 23052218 PMCID: PMC11113239 DOI: 10.1007/s00018-012-1178-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Revised: 09/19/2012] [Accepted: 09/24/2012] [Indexed: 12/21/2022]
Abstract
The schizophrenia susceptibility gene, Rgs4, is one of the most intensively studied regulators of G-protein signaling members, well known to be fundamental in regulating neurotransmission. However, little is known about its role in the developing nervous system. We have isolated zebrafish rgs4 and shown that it is transcribed in the developing nervous system. Rgs4 knockdown did not affect neuron number and patterning but resulted in locomotion defects and aberrant development of axons. This was confirmed using a selective Rgs4 inhibitor, CCG-4986. Rgs4 knockdown also attenuated the level of phosphorylated-Akt1, and injection of constitutively-activated AKT1 rescued the motility defects and axonal phenotypes in the spinal cord but not in the hindbrain and trigeminal neurons. Our in vivo analysis reveals a novel role for Rgs4 in regulating axonogenesis during embryogenesis, which is mediated by another schizophrenia-associated gene, Akt1, in a region-specific manner.
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Affiliation(s)
- Yi-Chuan Cheng
- Graduate Institute of Biomedical Sciences, School of Medicine, Chang Gung University, Taoyuan, 33383, Taiwan.
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12
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Liao WH, Cheng CH, Hung KS, Chiu WT, Chen GD, Hwang PP, Hwang SPL, Kuan YS, Huang CJ. Protein tyrosine phosphatase receptor type O (Ptpro) regulates cerebellar formation during zebrafish development through modulating Fgf signaling. Cell Mol Life Sci 2013; 70:2367-81. [PMID: 23361036 PMCID: PMC3676743 DOI: 10.1007/s00018-013-1259-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 12/13/2012] [Accepted: 01/03/2013] [Indexed: 02/04/2023]
Abstract
Protein activities controlled by receptor protein tyrosine phosphatases (RPTPs) play comparably important roles in transducing cell surface signals into the cytoplasm by protein tyrosine kinases. Previous studies showed that several RPTPs are involved in neuronal generation, migration, and axon guidance in Drosophila, and the vertebrate hippocampus, retina, and developing limbs. However, whether the protein tyrosine phosphatase type O (ptpro), one kind of RPTP, participates in regulating vertebrate brain development is largely unknown. We isolated the zebrafish ptpro gene and found that its transcripts are primarily expressed in the embryonic and adult central nervous system. Depletion of zebrafish embryonic Ptpro by antisense morpholino oligonucleotide knockdown resulted in prominent defects in the forebrain and cerebellum, and the injected larvae died on the 4th day post-fertilization (dpf). We further investigated the function of ptpro in cerebellar development and found that the expression of ephrin-A5b (efnA5b), a Fgf signaling induced cerebellum patterning factor, was decreased while the expression of dusp6, a negative-feedback gene of Fgf signaling in the midbrain-hindbrain boundary region, was notably induced in ptpro morphants. Further analyses demonstrated that cerebellar defects of ptpro morphants were partially rescued by inhibiting Fgf signaling. Moreover, Ptpro physically interacted with the Fgf receptor 1a (Fgfr1a) and dephosphorylated Fgfr1a in a dose-dependant manner. Therefore, our findings demonstrate that Ptpro activity is required for patterning the zebrafish embryonic brain. Specifically, Ptpro regulates cerebellar formation during zebrafish development through modulating Fgf signaling.
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Affiliation(s)
- Wei-Hao Liao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 104, Taiwan
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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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