Molecular chaperone function and motor neuron degeneration
Lead Research Organisation:
University College London
Department Name: Institute of Ophthalmology
Abstract
In order to co-ordinate movement, signals must be sent from the brain to the muscles along specialized nerve cells called motor neurons. Some of these motor neurons are very large and send signals over several feet, this makes their biology very challenging and means that they can be susceptible to stress and disease. When these motor neurons die it leads to paralysis. In some families this paralysis can be inherited because of genetic changes. Recently, it was discovered that inherited changes in a stress response protein called HSJ1 lead to paralysis through the death of motor neurons. We have been studying this protein for many years and know that it can protect nerve cells, including motor neurons, from stress. To function normally all cells need to balance their production of new proteins with their removal and this is especially important at times of stress, when proteins can get damaged. Therefore, evolution has developed a family of proteins called molecular chaperones to help maintain this balance and HSJ1 is an important molecular chaperone in nerve cells. To investigate how HSJ1 functions in nerve cells and understand why it is so critical to motor neurons, we have now reprogrammed cells from patients with inherited paralysis and will use them to study human motor neurons. We also have developed an animal model that mimics the human disease. In this project we will use these models to discover the molecular basis for paralysis in patients. It is likely that the events that cause paralysis in this disease will also affect how motor neurons function in other diseases and therefore we think this will tell us more about other types of motor neuron disease and nerve cell death in general. We will also use this detailed molecular understanding to develop new treatments that might be used for this type of paralysis and potentially other forms of nerve cell death such as motor neuron disease, Parkinson's and Alzheimer's disease.
Technical Summary
Many neurodegenerative diseases are characterised by intracellular proteinacious inclusions of aggregated, misfolded protein, suggesting that imbalances of protein homeostasis (proteostasis) are a factor in disease pathogenesis. Molecular chaperones are important regulators of proteostasis and the neuronal chaperone HSJ1 (DnaJB2) can protect against several types of neurodegeneration, including polyglutamine expanded huntingtin and mutant SOD1 in vivo. Furthermore, mutations that cause loss of HSJ1 function lead to distal hereditary motor neuropathy (dHMN) and Charcot-Marie-Tooth type 2 (CMT2), suggesting HSJ1 is particularly important for maintaining motor neuron proteostasis. This project aims to discover the precise molecular mechanisms that underlie the death of motor neurons caused by HSJ1 mutations. We have successfully reprogrammed HSJ1 patient cells to an induced pluripotent stem cell (iPSC) state and have developed a conditional HSJ1 knock-out (KO) mouse. The constitutive KO recapitulates the human phenotype, with death of motor neurons in the spinal cord. Here we will combine these models to understand motor neuron degeneration caused by loss of HSJ1. We will use a multidisciplinary approach to investigate specific functional deficits in iPSC motor neurons. Subsequently, we will rescue the cellular phenotype, by viral delivery of HSJ1 isoforms, to confirm the specificity of these functional defects, in parallel with investigating isoform specific mouse models, to define the HSJ1 isoform requirements for motor neuron survival. The client proteins of HSJ1 in motor neurons will be identified by a combined proteomic approach of identifying co-purifying proteins and monitoring changes in the proteome following loss of HSJ1. The interaction of putative clients with HSJ1 will be defined, and their importance for motor neuron survival tested. Finally, this mechanistic understanding will be used to test potential therapies for HSJ1 mediated dHMN.
Planned Impact
This research is directly relevant to the general public as neurodegeneration is a disease that affects most of us in some way, either directly or through affecting a loved one. What we discover about how motor neurons die could have a broader relevance to many forms of neurodegeneration. More specifically this research will be important to those affected by the many forms of motor neuron disease and the patient orientated groups that fund raise and motivate for funding to find effective treatments, such as the Motor Neurone Disease Association.
Furthermore, there are links between athletic excellence and achievement and motor neuron dysfunction and this research could be directly relevant to influencing how we can ensure that exercise does not have negative effects on nerve cell function. We will learn more about how neurons respond to environmental stress and this will be of interest to how we consider the environment and our interaction with it.
The research will also have impact on the biotech community. There are several small recently established Biotech companies that are pursuing potential pharmacological manipulation of molecular chaperones, protein folding and the cell stress machinery (heat shock response and unfolded protein response). Large Pharma are also interested in the potential of manipulating these pathways, either as targets in oncology or for their potential in alleviating neuronal dysfunction. Importantly, GSK is a collaborator on this project providing exclusive compounds for manipulation of the unfolded protein response and other Pharma have provided drugs (e.g. Novartis and HSP990). The data generated by this research project could have important impact for these potential applications in the future.
Furthermore, there are links between athletic excellence and achievement and motor neuron dysfunction and this research could be directly relevant to influencing how we can ensure that exercise does not have negative effects on nerve cell function. We will learn more about how neurons respond to environmental stress and this will be of interest to how we consider the environment and our interaction with it.
The research will also have impact on the biotech community. There are several small recently established Biotech companies that are pursuing potential pharmacological manipulation of molecular chaperones, protein folding and the cell stress machinery (heat shock response and unfolded protein response). Large Pharma are also interested in the potential of manipulating these pathways, either as targets in oncology or for their potential in alleviating neuronal dysfunction. Importantly, GSK is a collaborator on this project providing exclusive compounds for manipulation of the unfolded protein response and other Pharma have provided drugs (e.g. Novartis and HSP990). The data generated by this research project could have important impact for these potential applications in the future.
Publications
Kampinga HH
(2019)
Function, evolution, and structure of J-domain proteins.
in Cell stress & chaperones
Klionsky DJ
(2016)
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition).
in Autophagy
Ottaviani D
(2017)
Protein kinase CK2 modulates HSJ1 function through phosphorylation of the UIM2 domain.
in Human molecular genetics
Zarouchlioti C
(2018)
DNAJ Proteins in neurodegeneration: essential and protective factors.
in Philosophical transactions of the Royal Society of London. Series B, Biological sciences
Description | PhD studenthsip |
Amount | £92,537 (GBP) |
Organisation | Motor Neurone Disease Association (MND) |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 09/2016 |
End | 09/2019 |
Title | Isogenic knock-out lines |
Description | CRISPR mediated knock-out of DNAJB2 from control iPSC line to use as a control |
Type Of Material | Cell line |
Year Produced | 2018 |
Provided To Others? | No |
Impact | The line has just been developed and not used yet |
Title | Patient cell lines |
Description | Patient derived iPSC cell lines with differentiation to motor neurone |
Type Of Material | Cell line |
Provided To Others? | No |
Impact | The International Society for Stem Cell Research (ISSCR), StemBANCC and the Basel Stem Cell Network presented Translational Opportunities in Stem Cell Research, an ISSCR International Symposium, 27 February - 1 March, 2017, in Basel, Switzerland. Poster submission Generation of motor neurons from distal hereditary motor neuropathy patient-derived iPSCs Authors David A. Parfitt1, Heather L. Smith1 Lauren Gittings1, Michaela Auer-Grumbach2, Burkhard Gess3 and Michael E. Cheetham |
Title | Proteome of iPSC motor neurons |
Description | We have analysed the proteome of control and DNAJB2 null iPSC motor neurons produced in vitro |
Type Of Material | Database/Collection of data |
Year Produced | 2019 |
Provided To Others? | No |
Impact | The data are not yet publicly available as we are still analyzing the data |
Title | Proteome of lumbar spinal cord |
Description | We have produced a proteome from mouse lumbar spinal cord from control C57Bl6 mice and Dnajb2 knock-out mice at P15. |
Type Of Material | Database/Collection of data |
Year Produced | 2019 |
Provided To Others? | No |
Impact | The data are not yet publicly available as we are still analyzing them. |
Description | DNAJB2 patient stem cells |
Organisation | Medical University of Vienna |
Country | Austria |
Sector | Academic/University |
PI Contribution | We have produced iPSC cells and made motor neurone |
Collaborator Contribution | The partners provided patient fibroblasts for reprogramming |
Impact | The International Society for Stem Cell Research (ISSCR), StemBANCC and the Basel Stem Cell Network presented Translational Opportunities in Stem Cell Research, an ISSCR International Symposium, 27 February - 1 March, 2017, in Basel, Switzerland. Poster submission Generation of motor neurons from distal hereditary motor neuropathy patient-derived iPSCs Authors David A. Parfitt1, Heather L. Smith1 Lauren Gittings1, Michaela Auer-Grumbach2, Burkhard Gess3 and Michael E. Cheetham |
Start Year | 2015 |
Description | DNAJB2 patient stem cells |
Organisation | University of Münster |
Department | Faculty of Chemistry and Pharmacy |
Country | Germany |
Sector | Academic/University |
PI Contribution | We have produced iPSC cells and made motor neurone |
Collaborator Contribution | The partners provided patient fibroblasts for reprogramming |
Impact | The International Society for Stem Cell Research (ISSCR), StemBANCC and the Basel Stem Cell Network presented Translational Opportunities in Stem Cell Research, an ISSCR International Symposium, 27 February - 1 March, 2017, in Basel, Switzerland. Poster submission Generation of motor neurons from distal hereditary motor neuropathy patient-derived iPSCs Authors David A. Parfitt1, Heather L. Smith1 Lauren Gittings1, Michaela Auer-Grumbach2, Burkhard Gess3 and Michael E. Cheetham |
Start Year | 2015 |
Description | HSJ1 phosphorylation collaboration |
Organisation | University of Padova |
Country | Italy |
Sector | Academic/University |
PI Contribution | I have developed a collaboration with Dr Maria Ruzzene Padova to study HSJ1 phosphorylation. Her PhD student Daniele Ottaviani will spend 6 months in my lab. |
Collaborator Contribution | We are providing reagents and advice to study HSJ! phosphorylation. |
Impact | Daniele has received 2 fellowships to fund his visit from EMBO and Boehringer Ingelheim |
Start Year | 2015 |
Description | J protein workshop |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | 40 people attended a workshop focused on J proteins in Gdansk, a summary of this workshop was published in Cell Stress and Chaperones. We recommended changes in terminology and future research directions. |
Year(s) Of Engagement Activity | 2018 |
Description | Presentation at ISSCR conference |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | The International Society for Stem Cell Research (ISSCR), StemBANCC and the Basel Stem Cell Network presented Translational Opportunities in Stem Cell Research, an ISSCR International Symposium, 27 February - 1 March, 2017, in Basel, Switzerland. Poster submission Generation of motor neurons from distal hereditary motor neuropathy patient-derived iPSCs Authors David A. Parfitt1, Heather L. Smith1 Lauren Gittings1, Michaela Auer-Grumbach2, Burkhard Gess3 and Michael E. Cheetham |
Year(s) Of Engagement Activity | 2017 |
Description | Regulation of the neuroprotective chaperone DNAJB2 in motor neurons |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Presentation by Dr Parfitt at May 2017, Protein Quality Control EMBO Conference, Sant Feliu de Giuxols, Spain |
Year(s) Of Engagement Activity | 2017 |