The Role of Glycyl-tRNA Synthetase in Neurodegeneration
Lead Research Organisation:
University of Oxford
Department Name: Physiology Anatomy and Genetics
Abstract
Degenerative disorders of the nervous system place a significant and increasing healthcare burden as the average age of the population rises. In order to develop effective treatments, an understanding of how these disorders arise is critical. Relatively rare inherited diseases such as spinal muscular atrophy are an ideal paradigm with the insights gained expected to be broadly applicable to common conditions such as Alzheimer‘s and Parkinson‘s Disease.
We are studying a neurodegenerative disorder caused by mutations in the gene for Glycyl-tRNA Synthetase (GlyRS): an enzyme required by cells to ensure proteins are synthesised correctly from their genetic templates. However, motor nerves are particularly vulnerable to mutations in this enzyme. To understand why, we will examine the cells of mice to study how GlyRS mutations might change gene expression and affect motor nerve function. We will then examine the interactions of this ubiquitous enzyme with proteins that may be specific to motor nerves. Through determination of the atomic structures, the key parts of the enzyme mediating such interactions can be identified.
This research will yield fresh insights into how neurons degenerate and why they are vulnerable. This will then form the basis of new treatments for these appalling disorders.
We are studying a neurodegenerative disorder caused by mutations in the gene for Glycyl-tRNA Synthetase (GlyRS): an enzyme required by cells to ensure proteins are synthesised correctly from their genetic templates. However, motor nerves are particularly vulnerable to mutations in this enzyme. To understand why, we will examine the cells of mice to study how GlyRS mutations might change gene expression and affect motor nerve function. We will then examine the interactions of this ubiquitous enzyme with proteins that may be specific to motor nerves. Through determination of the atomic structures, the key parts of the enzyme mediating such interactions can be identified.
This research will yield fresh insights into how neurons degenerate and why they are vulnerable. This will then form the basis of new treatments for these appalling disorders.
Technical Summary
Glycyl-tRNA synthetase (GlyRS) is an essential enzyme for ensuring the fidelity of translation of the genetic code through ligation of glycine with its cognate tRNA. Several dominant mutations have been identified in GlyRS causing lower motor neuron disorders. A mouse model with a C201R GlyRS mutation has also been identified on the basis of a distal motor neuronopathy (grip-strength) phenotype. Our preliminary structure-function studies demonstrate that mutant GlyRS forms functional enzymes but activity, which may be increased or decreased, is not consistently correlated with the disease phenotype. Furthermore a GlyRS mutation, with increased enzyme activity, reduces survival of cultured neurons.
The aim of the proposed study is to understand how GlyRS mutations lead to neurodegeneration. We hypothesize that toxicity is mediated by a neuron-specific intermediary protein and this will be explored using the C201R mouse. We have therefore designed this project with the following specific objectives:
1. Characterisation of the C201R mouse a. Histopathology of peripheral nerves and neuromuscular junction b. Motor neuron culture transfection studies c. Gene expression profiling to reveal gene networks leading to neurodegeneration
2. Identifying GlyRS binding partners to reveal protein networks leading to neurodegeneration
3. Structure-biochemistry of GlyRS-substrate complexes
We will fully characterise the nature of the neurodegenerative process in C201R mice through electron microscopy and histopathology of peripheral nerves and muscle. Primary motor neuron cultures will be transfected with tagged axonal transport and synapse proteins and visualised with confocal microscopy. Changes in gene expression will be determined using DNA microarrays and real-time PCR.
A yeast two-hybrid screen, co-immunoprecipitation and mass spectrometry will be used to identify binding partners. GlyRS will be crystallised in complex with cognate tRNA and binding partners using high-throughput sitting-drop vapour diffusion and structures determined with publicly available bioinformatics resources. This will be correlated with GlyRS enzyme activity in-vitro and in-vivo using standard radio-labelled aminoacylation assays.
This project examines the neurodegenerative process from the most fundamental level of molecular architecture to the whole organism level. It represents a unique scientific opportunity to integrate several complementary disciplines; each placing the other in context and having the potential to provide greater insights into the mechanism of disease.
If the mechanism of toxicity in GlyRS mutations can be identified, drugs could be used to disrupt this process. GlyRS inhibitors already exist as do antibiotics targeting other aminoacyl-synthetases. Modification of these agents based upon structure-function work could eventually lead to effective treatments for neurodegenerative disorders.
The aim of the proposed study is to understand how GlyRS mutations lead to neurodegeneration. We hypothesize that toxicity is mediated by a neuron-specific intermediary protein and this will be explored using the C201R mouse. We have therefore designed this project with the following specific objectives:
1. Characterisation of the C201R mouse a. Histopathology of peripheral nerves and neuromuscular junction b. Motor neuron culture transfection studies c. Gene expression profiling to reveal gene networks leading to neurodegeneration
2. Identifying GlyRS binding partners to reveal protein networks leading to neurodegeneration
3. Structure-biochemistry of GlyRS-substrate complexes
We will fully characterise the nature of the neurodegenerative process in C201R mice through electron microscopy and histopathology of peripheral nerves and muscle. Primary motor neuron cultures will be transfected with tagged axonal transport and synapse proteins and visualised with confocal microscopy. Changes in gene expression will be determined using DNA microarrays and real-time PCR.
A yeast two-hybrid screen, co-immunoprecipitation and mass spectrometry will be used to identify binding partners. GlyRS will be crystallised in complex with cognate tRNA and binding partners using high-throughput sitting-drop vapour diffusion and structures determined with publicly available bioinformatics resources. This will be correlated with GlyRS enzyme activity in-vitro and in-vivo using standard radio-labelled aminoacylation assays.
This project examines the neurodegenerative process from the most fundamental level of molecular architecture to the whole organism level. It represents a unique scientific opportunity to integrate several complementary disciplines; each placing the other in context and having the potential to provide greater insights into the mechanism of disease.
If the mechanism of toxicity in GlyRS mutations can be identified, drugs could be used to disrupt this process. GlyRS inhibitors already exist as do antibiotics targeting other aminoacyl-synthetases. Modification of these agents based upon structure-function work could eventually lead to effective treatments for neurodegenerative disorders.
People |
ORCID iD |
Zam Cader (Principal Investigator / Fellow) |
Publications

Achilli F
(2009)
An ENU-induced mutation in mouse glycyl-tRNA synthetase (GARS) causes peripheral sensory and motor phenotypes creating a model of Charcot-Marie-Tooth type 2D peripheral neuropathy.
in Disease models & mechanisms

Benoy V
(2018)
HDAC6 is a therapeutic target in mutant GARS-induced Charcot-Marie-Tooth disease.
in Brain : a journal of neurology


Gayán J
(2008)
Genomewide linkage scan reveals novel loci modifying age of onset of Huntington's disease in the Venezuelan HD kindreds.
in Genetic epidemiology

Grice SJ
(2015)
Dominant, toxic gain-of-function mutations in gars lead to non-cell autonomous neuropathology.
in Human molecular genetics

Grice SJ
(2018)
Plexin-Semaphorin Signaling Modifies Neuromuscular Defects in a Drosophila Model of Peripheral Neuropathy.
in Frontiers in molecular neuroscience

Janssen BJ
(2012)
Neuropilins lock secreted semaphorins onto plexins in a ternary signaling complex.
in Nature structural & molecular biology

Lafrenière RG
(2010)
A dominant-negative mutation in the TRESK potassium channel is linked to familial migraine with aura.
in Nature medicine

Sleigh JN
(2014)
Neuromuscular junction maturation defects precede impaired lower motor neuron connectivity in Charcot-Marie-Tooth type 2D mice.
in Human molecular genetics

Sleigh JN
(2017)
Trk receptor signaling and sensory neuron fate are perturbed in human neuropathy caused by Gars mutations.
in Proceedings of the National Academy of Sciences of the United States of America
Description | IMI |
Amount | € 26,000,000 (EUR) |
Organisation | European Commission |
Department | Innovative Medicines Initiative (IMI) |
Sector | Public |
Country | Belgium |
Start | 08/2012 |
End | 09/2017 |
Description | OSCI Seed Funding (James Martin Fund) |
Amount | £20,000 (GBP) |
Organisation | University of Oxford |
Department | James Martin Fund |
Sector | Academic/University |
Country | United Kingdom |
Start | 08/2011 |
End | 09/2012 |
Description | Oxford University John Fell Fund Award |
Amount | £45,000 (GBP) |
Organisation | University of Oxford |
Department | John Fell Fund |
Sector | Academic/University |
Country | United Kingdom |
Start | 01/2007 |
End | 03/2015 |
Description | Project Grants |
Amount | € 93,000 (EUR) |
Organisation | French Muscular Dystrophy Association (AFM) |
Sector | Charity/Non Profit |
Country | France |
Start | 03/2013 |
End | 03/2015 |
Title | A Fly model of Glycyl-tRNA Synthetase |
Description | Flies expressing human GARS - wildtype and disease causing mutants |
Type Of Material | Model of mechanisms or symptoms - non-mammalian in vivo |
Provided To Others? | No |
Impact | This has provide significant insights into the time course of the neuro-degenerative process and convergence points for genetic interactors |
Title | An inducible GARS neuronal stable cell line |
Description | A lentiviral transduced NSC-34 cell line expressing Tet-ON GARS. Mitochondrial and cytoplasmic as well as wild-type and mutant isoforms |
Type Of Material | Cell line |
Year Produced | 2012 |
Provided To Others? | Yes |
Impact | This has allowed the characterization of the GARS transcriptome and proteome |
Title | Stem Cell Resources |
Description | Panel of cell lines from range of neurological and psychiatric disorders as well as diabetes and healthy controls. |
Type Of Material | Cell line |
Year Produced | 2014 |
Provided To Others? | Yes |
Impact | This will become accessbile to the international research community |
URL | http://stembancc.org/ |
Description | A fly model of GlyRS Neurodegeneration |
Organisation | University of Oxford |
Department | Department of Physiology, Anatomy and Genetics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Leading collaborative work |
Collaborator Contribution | Generation of a fly model of Glycyl-tRNA synthetase to identify pathogenic mechanism and to understand interactions with other genes involved in neurodegeneration |
Impact | A validated fly model of neurodegeneration |
Start Year | 2010 |
Description | StemBANCC |
Organisation | European Commission |
Department | Innovative Medicines Initiative (IMI) |
Country | Belgium |
Sector | Public |
PI Contribution | Leading this consortium |
Collaborator Contribution | 25 academic institutions 10 pharmaceutical companies providing 26 million euros in-kind contribution |
Impact | None |
Start Year | 2012 |
Description | StemBANCC |
Organisation | F. Hoffmann-La Roche AG |
Country | Global |
Sector | Private |
PI Contribution | Leading this consortium |
Collaborator Contribution | 25 academic institutions 10 pharmaceutical companies providing 26 million euros in-kind contribution |
Impact | None |
Start Year | 2012 |
Description | TRESK - a new gene for migraine |
Organisation | University of Montreal |
Country | Canada |
Sector | Academic/University |
PI Contribution | Co-ordinating and leading collaboration. |
Collaborator Contribution | This collaboration involved the electrophysiological characterization of TRESK in XenopusThe sequencing of migraine probands to identify variants in ion channel genes |
Impact | Identification of the first gene linked to typical migraine - TRESK. Publication in Nature Medicine Significant media coverage of findings |
Start Year | 2008 |
Description | TRESK - a new gene for migraine |
Organisation | University of Oxford |
Department | Department of Physics |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Co-ordinating and leading collaboration. |
Collaborator Contribution | This collaboration involved the electrophysiological characterization of TRESK in XenopusThe sequencing of migraine probands to identify variants in ion channel genes |
Impact | Identification of the first gene linked to typical migraine - TRESK. Publication in Nature Medicine Significant media coverage of findings |
Start Year | 2008 |
Description | Mechanisms of Migraine, Migraine Trust Meeting |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Participants in your research and patient groups |
Results and Impact | 100 migraine and headache sufferers attended a talk on the mechanisms of migraine. There was a question and answer session following the talk There was significant interest in the talk such that other patient groups have subsequently requested further talks |
Year(s) Of Engagement Activity | 2010 |
Description | TRESK and Migraine Breaking News |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Widespread coverage of Nature Medicine publication by newspapers, radio and TV worldwide Numerous emails and other communications with congratulations or requests of interest to participate in research |
Year(s) Of Engagement Activity | 2010 |