Role of autophagy in the accumulation of defective mitochondria during ageing
Lead Research Organisation:
Newcastle University
Department Name: Biosciences Institute
Abstract
The progressive ageing of the UK population is one of the most serious problems our society will face during the 21st century. The increase in the number of people suffering from age-related diseases is a heavy burden on the NHS and threatens to collapse one of the best health care systems in the world.
The simplest and most cost effective solution to the "ageing problem" is to find ways to delay the rate of ageing, extending healthy lifespan, delaying the onset of age-related diseases and therefore extending the time an individual can remain fully independent. To delay ageing, we must fully understand the complex mechanisms that drive it and how they are connected.
Mitochondria are the powerhouses of the cell, generating the majority of ATP, the cellular currency required to keep cells going. As in any other factory, mitochondria generate harmful waste and require maintenance from time to time. Autophagy is the main way that the cell achieves this. It is responsible for removal and recycling of damaged components to keep the cell, including mitochondria, in optimal working condition. With age, the capacity of autophagy to do this declines. At the same time damaged mitochondria also accumulate, causing depletion of ATP, which leads to cell death and neurodegeneration and is associated with diseases such as Parkinson's or Alzheimer's disease.
We have found a new mechanism that connects the age associated reduction in autophagy efficiency and the accumulation of defective mitochondria. Importantly this mechanism can be targeted with drugs that are already in use in the clinic. When autophagy is interrupted, either genetically or during aging, respiratory complex I (CI) which mitochondria need to produce energy, stops working properly and starts to generate an abnormally high amount of harmful waste in the form of free radicals which can cause cell death and accelerate ageing. We have discovered that by-passing CI or restoring its function prevents cell death and extends lifespan.
We will develop a research program that will use a combination of in vitro and in vivo models to establish the connection between autophagy and mitochondria in ageing. Firstly, we will investigate how cell death is induced in autophagy-deficient cells, restoring CI function and rescuing cell death. Secondly, we will use the powerful genetics of the fruit fly to find out how loss of autophagy causes the accumulation of damaged mitochondria and measure it effect on the ageing process. Finally, we will boost autophagy and/or mitochondrial function to ask if by-passing CI in old individuals is enough to delay ageing. By the end of this project, we will have identified key mechanisms that drive ageing and can be targeted with therapies which are already clinically approved.
The simplest and most cost effective solution to the "ageing problem" is to find ways to delay the rate of ageing, extending healthy lifespan, delaying the onset of age-related diseases and therefore extending the time an individual can remain fully independent. To delay ageing, we must fully understand the complex mechanisms that drive it and how they are connected.
Mitochondria are the powerhouses of the cell, generating the majority of ATP, the cellular currency required to keep cells going. As in any other factory, mitochondria generate harmful waste and require maintenance from time to time. Autophagy is the main way that the cell achieves this. It is responsible for removal and recycling of damaged components to keep the cell, including mitochondria, in optimal working condition. With age, the capacity of autophagy to do this declines. At the same time damaged mitochondria also accumulate, causing depletion of ATP, which leads to cell death and neurodegeneration and is associated with diseases such as Parkinson's or Alzheimer's disease.
We have found a new mechanism that connects the age associated reduction in autophagy efficiency and the accumulation of defective mitochondria. Importantly this mechanism can be targeted with drugs that are already in use in the clinic. When autophagy is interrupted, either genetically or during aging, respiratory complex I (CI) which mitochondria need to produce energy, stops working properly and starts to generate an abnormally high amount of harmful waste in the form of free radicals which can cause cell death and accelerate ageing. We have discovered that by-passing CI or restoring its function prevents cell death and extends lifespan.
We will develop a research program that will use a combination of in vitro and in vivo models to establish the connection between autophagy and mitochondria in ageing. Firstly, we will investigate how cell death is induced in autophagy-deficient cells, restoring CI function and rescuing cell death. Secondly, we will use the powerful genetics of the fruit fly to find out how loss of autophagy causes the accumulation of damaged mitochondria and measure it effect on the ageing process. Finally, we will boost autophagy and/or mitochondrial function to ask if by-passing CI in old individuals is enough to delay ageing. By the end of this project, we will have identified key mechanisms that drive ageing and can be targeted with therapies which are already clinically approved.
Technical Summary
Ageing is one of the most important biomedical challenges of the 21st century. Understanding the underlying mechanisms that drive ageing will provide us with the tools to solve the "ageing problem". Two hallmarks of ageing are diminished autopaghic capacity and accumulation of defective mitochondria.
Autophagy is instrumental for recycling damaged cellular components including mitochondria. Accordingly mutations in genes encoding the autophagy machinery cause severe neurodegeneration. Similarly, mitochondria are essential to produce cellular energy, and mutations in mitochondrial genes cause devastating diseases. Unfortunately, how autophagy dysfunction contributes to the accumulation of respiratory-deficient mitochondria in ageing remains to be established.
We have uncovered a new mechanism where genetic or age-related disruption of autophagy causes accumulation of dysfunctional mitochondria. These mitochondria generate less ATP and more Reactive Oxygen Species (ROS). Interestingly respiratory complex I (CI) is selectively affected in both autophagy-deficient cells and old individuals. CI is the largest respiratory enzyme and main generator of ROS, triggering cell death via apoptosis during dysfunction.
Our research program will determine how decreased autophagic capacity contributes to the accumulation of respiratory-deficient mitochondria and the role of CI in ageing. Firstly, we will investigate how CI triggers apoptosis. Secondly, we will determine how disrupted autophagy leads to the accumulation of CI-deficient mitochondria and how this affects ageing. Finally, we will implement genetic, pharmacological and dietary interventions to boost autophagy and restore CI function, extending healthy lifespan. Our project will provide us with specific targets that can be manipulated with clinically approved drugs, allowing a swift translation of our findings.
Autophagy is instrumental for recycling damaged cellular components including mitochondria. Accordingly mutations in genes encoding the autophagy machinery cause severe neurodegeneration. Similarly, mitochondria are essential to produce cellular energy, and mutations in mitochondrial genes cause devastating diseases. Unfortunately, how autophagy dysfunction contributes to the accumulation of respiratory-deficient mitochondria in ageing remains to be established.
We have uncovered a new mechanism where genetic or age-related disruption of autophagy causes accumulation of dysfunctional mitochondria. These mitochondria generate less ATP and more Reactive Oxygen Species (ROS). Interestingly respiratory complex I (CI) is selectively affected in both autophagy-deficient cells and old individuals. CI is the largest respiratory enzyme and main generator of ROS, triggering cell death via apoptosis during dysfunction.
Our research program will determine how decreased autophagic capacity contributes to the accumulation of respiratory-deficient mitochondria and the role of CI in ageing. Firstly, we will investigate how CI triggers apoptosis. Secondly, we will determine how disrupted autophagy leads to the accumulation of CI-deficient mitochondria and how this affects ageing. Finally, we will implement genetic, pharmacological and dietary interventions to boost autophagy and restore CI function, extending healthy lifespan. Our project will provide us with specific targets that can be manipulated with clinically approved drugs, allowing a swift translation of our findings.
Planned Impact
Bioscience for health is one of the BBSRC strategic areas and within this area, extending population health span and increasing the independence of senior citizens is at the top of the list of priorities. The present consensus is that fundamental research directed at understanding the proximal causes of ageing is the most promising strategy to extend healthy lifespan. Our research program will operate under this paradigm determining the role autophagy and mitochondria play in ageing.
In the short term our research will have impact on ACADEMIC RESEARCHERS providing them with new knowledge about basic mechanisms of ageing. Our work will provide new tools and targets for drugs to CLINICIANS and HEALTH PROFESSIONALS working on ageing and degenerative diseases. A non-exclusive list includes: cancer, diabetes, immune diseases, Parkinson's disease and mitochondrial disease. In the long term, we aspire to develop treatments or interventions to prevent, delay or reverse ageing and extend healthy lifespan. Since both autophagy and mitochondria have been extensively studied, there are a number of clinically approved drugs (e.g. metformin, rapamycin or the bromodomain inhibitor I-BET 525762A).
Delaying ageing and age-related diseases will have an enormous IMPACT ON SOCIETY. One of the main problems the United Kingdom faces is the rising number of elderly people requiring more and more help to preserve their independence for longer. Alzheimer's disease, diabetes type II, sarcopenia, cancer or age-related cataracts are just a few examples of diseases and conditions that increase frailty and reduce the quality of life of the aged population. Finding a way to boost cellular energy levels in elderly citizens will contribute to this strategy by reducing frailty, extending their independence and dramatically reducing health care costs.
INDUSTRY will benefit from the possibility to perform drug screens in the in vivo and ex vivo models we will generate. Identifying novel or repurposing existing drugs that can prevent, delay or reverse the accumulation of dysfunctional mitochondria will open new markets, significantly increasing the revenue of the pharmaceutical industry. Ageing and age-related diseases will be a highly profitable market for pharmaceutical industry in the future. Our work will generate a list of drugs to be tested in higher model organisms or in humans. We will consider opportunities for commercialization in collaboration with the Newcastle University business development office who will evaluate the potential translational impact and industrial interaction of our research.
To boost the impact of our work, we will publish open access articles in high quality, broad readership journals and communicating our research via oral and poster presentations at scientific meetings before publication. We will take advantage of the websites of Newcastle University (including our own institute and laboratories), as well as social media (Twitter, Facebook) to actively promote our findings. The Newcastle University Press Office will be involved to ensure our findings are disseminated to the wider public as much as possible. Furthermore, we will generate opportunities throughout the project to disseminate and discuss our work with the general public, for whom the topic of healthy ageing is both accessible and interesting.
One of the most immediate impacts will be the CAREER DEVELOPMENT of the PDRA, RT and students who will learn and develop laboratory, analytical and writing skills, all of which are required for a successful career in science and to tackle age-related problems. Our cutting-edge research involving a number of latest TECHNOLOGIES will also train new SKILLED RESEARCHERS in UK.
In the short term our research will have impact on ACADEMIC RESEARCHERS providing them with new knowledge about basic mechanisms of ageing. Our work will provide new tools and targets for drugs to CLINICIANS and HEALTH PROFESSIONALS working on ageing and degenerative diseases. A non-exclusive list includes: cancer, diabetes, immune diseases, Parkinson's disease and mitochondrial disease. In the long term, we aspire to develop treatments or interventions to prevent, delay or reverse ageing and extend healthy lifespan. Since both autophagy and mitochondria have been extensively studied, there are a number of clinically approved drugs (e.g. metformin, rapamycin or the bromodomain inhibitor I-BET 525762A).
Delaying ageing and age-related diseases will have an enormous IMPACT ON SOCIETY. One of the main problems the United Kingdom faces is the rising number of elderly people requiring more and more help to preserve their independence for longer. Alzheimer's disease, diabetes type II, sarcopenia, cancer or age-related cataracts are just a few examples of diseases and conditions that increase frailty and reduce the quality of life of the aged population. Finding a way to boost cellular energy levels in elderly citizens will contribute to this strategy by reducing frailty, extending their independence and dramatically reducing health care costs.
INDUSTRY will benefit from the possibility to perform drug screens in the in vivo and ex vivo models we will generate. Identifying novel or repurposing existing drugs that can prevent, delay or reverse the accumulation of dysfunctional mitochondria will open new markets, significantly increasing the revenue of the pharmaceutical industry. Ageing and age-related diseases will be a highly profitable market for pharmaceutical industry in the future. Our work will generate a list of drugs to be tested in higher model organisms or in humans. We will consider opportunities for commercialization in collaboration with the Newcastle University business development office who will evaluate the potential translational impact and industrial interaction of our research.
To boost the impact of our work, we will publish open access articles in high quality, broad readership journals and communicating our research via oral and poster presentations at scientific meetings before publication. We will take advantage of the websites of Newcastle University (including our own institute and laboratories), as well as social media (Twitter, Facebook) to actively promote our findings. The Newcastle University Press Office will be involved to ensure our findings are disseminated to the wider public as much as possible. Furthermore, we will generate opportunities throughout the project to disseminate and discuss our work with the general public, for whom the topic of healthy ageing is both accessible and interesting.
One of the most immediate impacts will be the CAREER DEVELOPMENT of the PDRA, RT and students who will learn and develop laboratory, analytical and writing skills, all of which are required for a successful career in science and to tackle age-related problems. Our cutting-edge research involving a number of latest TECHNOLOGIES will also train new SKILLED RESEARCHERS in UK.
Publications
Garcia-Macia M
(2021)
A Mammalian Target of Rapamycin-Perilipin 3 (mTORC1-Plin3) Pathway is essential to Activate Lipophagy and Protects Against Hepatosteatosis.
in Hepatology (Baltimore, Md.)
Sedlackova L
(2020)
Autophagy promotes cell and organismal survival by maintaining NAD(H) pools
Kataura T
(2022)
Autophagy promotes cell survival by maintaining NAD levels.
in Developmental cell
Scialo F
(2021)
Coenzyme Q redox signalling and longevity
in Free Radical Biology and Medicine
Navas P
(2021)
Editorial: "Mitochondrial coenzyme Q homeostasis: Signalling, respiratory chain stability and diseases.".
in Free radical biology & medicine
Sanz A
(2018)
Editorial: Coenzyme Q Redox State and Cellular Homeostasis.
in Frontiers in physiology
Ashor AW
(2020)
Effects of inorganic nitrate and vitamin C co-supplementation on blood pressure and vascular function in younger and older healthy adults: A randomised double-blind crossover trial.
in Clinical nutrition (Edinburgh, Scotland)
Klionsky DJ
(2021)
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.
in Autophagy
Carillo MR
(2020)
L-Carnitine in Drosophila: A Review.
in Antioxidants (Basel, Switzerland)
Scialò F
(2020)
Mitochondrial complex I derived ROS regulate stress adaptation in Drosophila melanogaster.
in Redox biology
Description | Autophagy is the primary mechanism by which cells eliminate damaged components, including mitochondria. Elimination of damaged mitochondria is particularly crucial since they provide most of the cellular energy in the form of ATP. Reduced autophagy is a hallmark of ageing and age-related diseases. In parallel, ageing is characterized by the accumulation of defective mitochondria. We have generated cellular models where autophagy is interrupted due to mutations in genes essential for the process such as atg5. Interestingly, autophagy-deficient cells survive without problems in a glucose-rich media where glycolysis is the leading way to generate ATP. However, the same cells die very fast when they are forced to use oxidative phosphorylation. Our data indicate that autophagy deficiency triggers an NAD+ crisis in different cellular models. NAD+ is depleted due to its extensive use in repairing tasks (particularly DNA damaged by PARPs and sirtuins). Our data indicate that the "CI-defect" observed in autophagy-deficient cells is, in fact, an adaptation to diminished NAD+ levels and contributes to minimizing cell death. Our results show that preventing NAD+ depletion (either boosting its synthesis or preventing its degradation) is the best strategy to reduce cell death in mammalian cellular models. Interestingly, preventing the depletion of NAD(H) or boosting NAD+ synthesis is possible to rescue the lethal phenotype associated with autophagy deficiency in yeast, flies and human cells. Our discoveries open the door to new treatments for both ageing and age-related diseases. |
Exploitation Route | Our discoveries open the door to new treatments for both ageing and age-related diseases where autophagy is severely decreased. Boosting NAD+ levels is possible using compounds that are already available in the market. Our results support that the strategy works in yeast, Drosophila flies and human cells. The previous exciting results invite to test the same NAD+ boosters compounds in mouse models as a preliminary phase before planning clinical trials. |
Sectors | Chemicals Healthcare Pharmaceuticals and Medical Biotechnology |
Description | Identification of Parkinson disease-specific mitochondrial pathogenesis for disease-modifying therapy |
Amount | £93,243 (GBP) |
Organisation | Japan Society for the Promotion of Science (JSPS) |
Sector | Public |
Country | Japan |
Start | 02/2019 |
End | 01/2022 |
Description | Identification of active ingredients targets to prevent skin ageing |
Amount | £98,212 (GBP) |
Funding ID | BB/R506345/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2017 |
End | 09/2021 |
Description | Mitochondrial redox protein quality control in ageing |
Amount | £532,275 (GBP) |
Funding ID | BB/W002892/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 03/2022 |
End | 09/2025 |
Description | Senior Research Fellowship, |
Amount | £1,512,586 (GBP) |
Funding ID | 212241/Z/18/Z |
Organisation | Wellcome Trust |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 04/2019 |
End | 04/2024 |
Description | Why do mitochondria produce more ROS when we age? |
Amount | £446,952 (GBP) |
Funding ID | BB/W006774/1 |
Organisation | Biotechnology and Biological Sciences Research Council (BBSRC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2022 |
End | 01/2025 |
Title | New Drosophila strain with increased stress resistance |
Description | New fruit fly model generated by CRIRSR/Cas9 genomic editing |
Type Of Material | Model of mechanisms or symptoms - non-mammalian in vivo |
Year Produced | 2018 |
Provided To Others? | Yes |
Impact | Improved understanding of antioxidant defence mechanisms and the tool to study these in vivo |
URL | https://www.nature.com/articles/s41467-017-02746-z |
Description | Collaboration to characterize the metabolome of cellular and fly models of autophagy dysfunction. |
Organisation | University of Glasgow |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We provide Dr Oliver Maddocks with different cellular models where autophagy is disrupted and cells are cultured in either glucose or galactose. In addition, we implement different treatments that improve survival of autophagy deficient cells. We aim to determine the metabolic changes behind such an improvement |
Collaborator Contribution | Combining targeted and untargeted metabolomics the laboratory of Dr Maddocks produces multiple metabolic measurements including the main metabolites belonging to glycolysis, Pentose Phosphate Pathway, Kreb's cycle, nucleotide metabolism, etc. that are altered in our cellular models of autophagy deficiency. |
Impact | This collaboration has made possible a better understanding of the metabolic changes caused by autophagy deficiency providing us with therapeutic targets to improve the deleterious phenotypes observed. |
Start Year | 2018 |
Description | Collaboration to generate a neuronal model of autophagy deficiency. |
Organisation | University of Birmingham |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We provide Dr Sarkar with different models of autophagy deficiency cells and with expertise and information about mitochondrial function and techniques to evaluate mitochondrial activity, ROS production, etc. |
Collaborator Contribution | Dr Sarkar has generated human neurons differentiated from autophagy knockout human embryonic stem cells to test whether the phenotypes observed in fibroblast are conserved in this more relevant neurodegenerative disease model. In addition, we shall be able to test whether different therapeutic approaches to compensate autophagy deficiency also work in neurons. |
Impact | This collaboration provides us with an additional cellular model where to test whether the results observed in mouse fibroblasts also occur in another cellular type. Due to the fact, that many neurodegenerative diseases are associated with dysregulation of mechanism of quality control (such as autophagy), these neuronal models are highly relevant to validate new therapeutic targets. |
Start Year | 2018 |
Description | Collaboration to measure superoxide levels ex vivo and in vivo. |
Organisation | University of Cambridge |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We use the superoxide detector provided by the laboratories of Profs Murphy and Hartley (MitoNeoD) to estimate superoxide levels in cells and fly tissues. We provide them with feedback about how the probe works in different cell types and fly tissues. |
Collaborator Contribution | Profs Harley and Murphy has provided us with MitoNeoD a modified version of MitoSox (a superoxide fluorescent probe) that fixes many of the problems associated with the latest e.g. lack of specificity, problems with DNA intercalation, etc. |
Impact | This collaboration allows a better estimation of the real levels of superoxide in our research models. |
Start Year | 2018 |
Description | Collaboration to measure superoxide levels ex vivo and in vivo. |
Organisation | University of Glasgow |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We use the superoxide detector provided by the laboratories of Profs Murphy and Hartley (MitoNeoD) to estimate superoxide levels in cells and fly tissues. We provide them with feedback about how the probe works in different cell types and fly tissues. |
Collaborator Contribution | Profs Harley and Murphy has provided us with MitoNeoD a modified version of MitoSox (a superoxide fluorescent probe) that fixes many of the problems associated with the latest e.g. lack of specificity, problems with DNA intercalation, etc. |
Impact | This collaboration allows a better estimation of the real levels of superoxide in our research models. |
Start Year | 2018 |
Description | Collaboration to measure the effect of disrupting autophagy in Saccharomyces cerevisae. |
Organisation | Newcastle University |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We provide knowledge to study the effects of autophagy disruption on Saccharomyces cerevisiae. |
Collaborator Contribution | The group lead by Dr Manolis Papamichos Chronakis has provided us with data showing the effect of disrupting autophagy in yeast and how the defect in growth can be partially rescued by providing the cells with NAD+ precursors. |
Impact | The experiments performed by Dr Papamichos Chronakis have shown that the response to disruption in autophagy is conserved from yeast to humans. |
Start Year | 2018 |
Description | Collaboration to measure the impact of defects in autophagy on Caenorhabiditis elegans healthspan |
Organisation | Durham University |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We provide the team lead by Dr Weinkove with knowledge on how to generate models of autophagy deficiency in worms. Besides, we genotype the worms to confirm that specific genes were knocked down. |
Collaborator Contribution | Dr Weinkove provides us with measurements of healthspan of mutant and control worms using the automated system developed by his research group. |
Impact | We have obtained information about the effect of disrupting autophagy in worms (C. elegans) |
Start Year | 2019 |
Description | Synthesis of new molecules to extend healthy ageing |
Organisation | National Research Council |
Country | Italy |
Sector | Public |
PI Contribution | We will provide our collaborators with a list of potential targets that will be used to synthetize new molecules that have the potential to extend heathy ageing . |
Collaborator Contribution | Our collaborators will provide us with new molecules with the potential to extend healthy ageing and fight age-related diseases. |
Impact | This collaboration is helping us understand which proteins are important in extending healthy ageing |
Start Year | 2018 |
Description | Cell Detectives event at the Newcastle Centre for Life |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | The PI and members of the laboratory were involved in a research exhibition at the Newcastle Centre for Life with approximately 500 children and parents attending the event |
Year(s) Of Engagement Activity | 2019 |
Description | Co-organize and co-chair of Redox Signalling in Physiology, Ageing and Disease co-organized by the Biochemical Society and the British Society for Research on Ageing |
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 | Organization of the scientific conference "Redox Signalling in Physiology, Ageing and Disease" supported by the Biochemical Society and the British Society for Research on Ageing with over 100 attendants. |
Year(s) Of Engagement Activity | 2019 |
URL | https://www.eventsforce.net/biochemsoc/frontend/reg/thome.csp?pageID=20523&eventID=48&traceRedir=2 |
Description | Press release on our recent publication |
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 | Media (as a channel to the public) |
Results and Impact | Our press release was covered by several news agencies. |
Year(s) Of Engagement Activity | 2018 |
URL | https://www.ncl.ac.uk/press/articles/archive/2018/01/howdidweevolvetolivelonger/ |
Description | Public Session on ageing |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | As part of the research conference on Redox Biology and Ageing the PI co-organised a Public Session where a lay audience (approx. 100) with an interest in the Biology of Ageing was provided with the opportunity to ask questions from the leaders in the field. |
Year(s) Of Engagement Activity | 2019 |
URL | https://www.eventsforce.net/biochemsoc/frontend/reg/thome.csp?pageID=20523&eventID=48&traceRedir=2 |