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Granat L, Knorr DY, Ranson DC, Chakrabarty RP, Chandel NS, Bateman JM. A Drosophila model of mitochondrial disease phenotypic heterogeneity. Biol Open 2024; 13:bio060278. [PMID: 38304969 PMCID: PMC10924217 DOI: 10.1242/bio.060278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 01/22/2024] [Indexed: 02/03/2024] Open
Abstract
Mutations in genes that affect mitochondrial function cause primary mitochondrial diseases. Mitochondrial diseases are highly heterogeneous and even patients with the same mitochondrial disease can exhibit broad phenotypic heterogeneity, which is poorly understood. Mutations in subunits of mitochondrial respiratory complex I cause complex I deficiency, which can result in severe neurological symptoms and death in infancy. However, some complex I deficiency patients present with much milder symptoms. The most common nuclear gene mutated in complex I deficiency is the highly conserved core subunit NDUFS1. To model the phenotypic heterogeneity in complex I deficiency, we used RNAi lines targeting the Drosophila NDUFS1 homolog ND-75 with different efficiencies. Strong knockdown of ND-75 in Drosophila neurons resulted in severe behavioural phenotypes, reduced lifespan, altered mitochondrial morphology, reduced endoplasmic reticulum (ER)-mitochondria contacts and activation of the unfolded protein response (UPR). By contrast, weak ND-75 knockdown caused much milder behavioural phenotypes and changes in mitochondrial morphology. Moreover, weak ND-75 did not alter ER-mitochondria contacts or activate the UPR. Weak and strong ND-75 knockdown resulted in overlapping but distinct transcriptional responses in the brain, with weak knockdown specifically affecting proteosome activity and immune response genes. Metabolism was also differentially affected by weak and strong ND-75 knockdown including gamma-aminobutyric acid (GABA) levels, which may contribute to neuronal dysfunction in ND-75 knockdown flies. Several metabolic processes were only affected by strong ND-75 knockdown including the pentose phosphate pathway and the metabolite 2-hydroxyglutarate (2-HG), suggesting 2-HG as a candidate biomarker of severe neurological mitochondrial disease. Thus, our Drosophila model provides the means to dissect the mechanisms underlying phenotypic heterogeneity in mitochondrial disease.
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Affiliation(s)
- Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RX, UK
| | - Debbra Y. Knorr
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RX, UK
| | - Daniel C. Ranson
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RX, UK
| | - Ram Prosad Chakrabarty
- Department of Medicine, Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Navdeep S. Chandel
- Department of Medicine, Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Joseph M. Bateman
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RX, UK
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2
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Granat L, Knorr DY, Ranson DC, Hamer EL, Chakrabarty RP, Mattedi F, Fort-Aznar L, Hirth F, Sweeney ST, Vagnoni A, Chandel NS, Bateman JM. Yeast NDI1 reconfigures neuronal metabolism and prevents the unfolded protein response in mitochondrial complex I deficiency. PLoS Genet 2023; 19:e1010793. [PMID: 37399212 PMCID: PMC10348588 DOI: 10.1371/journal.pgen.1010793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 07/14/2023] [Accepted: 05/22/2023] [Indexed: 07/05/2023] Open
Abstract
Mutations in subunits of the mitochondrial NADH dehydrogenase cause mitochondrial complex I deficiency, a group of severe neurological diseases that can result in death in infancy. The pathogenesis of complex I deficiency remain poorly understood, and as a result there are currently no available treatments. To better understand the underlying mechanisms, we modelled complex I deficiency in Drosophila using knockdown of the mitochondrial complex I subunit ND-75 (NDUFS1) specifically in neurons. Neuronal complex I deficiency causes locomotor defects, seizures and reduced lifespan. At the cellular level, complex I deficiency does not affect ATP levels but leads to mitochondrial morphology defects, reduced endoplasmic reticulum-mitochondria contacts and activation of the endoplasmic reticulum unfolded protein response (UPR) in neurons. Multi-omic analysis shows that complex I deficiency dramatically perturbs mitochondrial metabolism in the brain. We find that expression of the yeast non-proton translocating NADH dehydrogenase NDI1, which reinstates mitochondrial NADH oxidation but not ATP production, restores levels of several key metabolites in the brain in complex I deficiency. Remarkably, NDI1 expression also reinstates endoplasmic reticulum-mitochondria contacts, prevents UPR activation and rescues the behavioural and lifespan phenotypes caused by complex I deficiency. Together, these data show that metabolic disruption due to loss of neuronal NADH dehydrogenase activity cause UPR activation and drive pathogenesis in complex I deficiency.
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Affiliation(s)
- Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Debbra Y. Knorr
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Daniel C. Ranson
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Emma L. Hamer
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Ram Prosad Chakrabarty
- Department of Medicine and Biochemistry & Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Francesca Mattedi
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Laura Fort-Aznar
- Department of Biology and York Biomedical Research Institute, University of York, Heslington, York, United Kingdom
- Alzheimer’s disease and other cognitive disorders Unit, Hospital Clínic de Barcelona IDIBAPS, Universitat de Barcelona, Barcelona, Spain
| | - Frank Hirth
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Sean T. Sweeney
- Department of Biology and York Biomedical Research Institute, University of York, Heslington, York, United Kingdom
| | - Alessio Vagnoni
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Navdeep S. Chandel
- Department of Medicine and Biochemistry & Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Joseph M. Bateman
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
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Baskaran P, Mihaylov SR, Vinsland E, Shah K, Granat L, Ultanir SK, Tee AR, Murn J, Bateman JM. Phosphorylation of the novel mTOR substrate Unkempt regulates cellular morphogenesis. J Biol Chem 2023; 299:102788. [PMID: 36509146 PMCID: PMC9852543 DOI: 10.1016/j.jbc.2022.102788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
Mechanistic target of rapamycin (mTOR) is a protein kinase that integrates multiple inputs to regulate anabolic cellular processes. For example, mTOR complex 1 (mTORC1) has key functions in growth control, autophagy, and metabolism. However, much less is known about the signaling components that act downstream of mTORC1 to regulate cellular morphogenesis. Here, we show that the RNA-binding protein Unkempt, a key regulator of cellular morphogenesis, is a novel substrate of mTORC1. We show that Unkempt phosphorylation is regulated by nutrient levels and growth factors via mTORC1. To analyze Unkempt phosphorylation, we immunoprecipitated Unkempt from cells in the presence or the absence of the mTORC1 inhibitor rapamycin and used mass spectrometry to identify mTORC1-dependent phosphorylated residues. This analysis showed that mTORC1-dependent phosphorylation is concentrated in a serine-rich intrinsically disordered region in the C-terminal half of Unkempt. We also found that Unkempt physically interacts with and is directly phosphorylated by mTORC1 through binding to the regulatory-associated protein of mTOR, Raptor. Furthermore, analysis in the developing brain of mice lacking TSC1 expression showed that phosphorylation of Unkempt is mTORC1 dependent in vivo. Finally, mutation analysis of key serine/threonine residues in the serine-rich region indicates that phosphorylation inhibits the ability of Unkempt to induce a bipolar morphology. Phosphorylation within this serine-rich region thus profoundly affects the ability of Unkempt to regulate cellular morphogenesis. Taken together, our findings reveal a novel molecular link between mTORC1 signaling and cellular morphogenesis.
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Affiliation(s)
- Pranetha Baskaran
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Simeon R Mihaylov
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK; Kinases and Brain Development Lab, The Francis Crick Institute, London, UK
| | - Elin Vinsland
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK; Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Kriti Shah
- Department of Biochemistry, University of California, Riverside, California, USA
| | - Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Sila K Ultanir
- Kinases and Brain Development Lab, The Francis Crick Institute, London, UK
| | - Andrew R Tee
- Cancer and Genetics Building, Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park Way, Cardiff, UK
| | - Jernej Murn
- Department of Biochemistry, University of California, Riverside, California, USA.
| | - Joseph M Bateman
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK.
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Phadke L, Lau DHW, Aghaizu ND, Ibarra S, Navarron CM, Granat L, Magno L, Whiting P, Jolly S. A primary rodent triculture model to investigate the role of glia-neuron crosstalk in regulation of neuronal activity. Front Aging Neurosci 2022; 14:1056067. [DOI: 10.3389/fnagi.2022.1056067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/07/2022] [Indexed: 12/03/2022] Open
Abstract
Neuroinflammation and hyperexcitability have been implicated in the pathogenesis of neurodegenerative disease, and new models are required to investigate the cellular crosstalk involved in these processes. We developed an approach to generate a quantitative and reproducible triculture system that is suitable for pharmacological studies. While primary rat cells were previously grown in a coculture medium formulated to support only neurons and astrocytes, we now optimised a protocol to generate tricultures containing neurons, astrocytes and microglia by culturing in a medium designed to support all three cell types and adding exogenous microglia to cocultures. Immunocytochemistry was used to confirm the intended cell types were present. The percentage of ramified microglia in the tricultures decreases as the number of microglia present increases. Multi-electrode array recordings indicate that microglia in the triculture model suppress neuronal activity in a dose-dependent manner. Neurons in both cocultures and tricultures are responsive to the potassium channel blocker 4-aminopyridine, suggesting that neurons remained viable and functional in the triculture model. Furthermore, suppressed neuronal activity in tricultures correlates with decreased densities of dendritic spines and of the postsynaptic protein Homer1 along dendrites, indicative of a direct or indirect effect of microglia on synapse function. We thus present a functional triculture model, which, due to its more complete cellular composition, is a more relevant model than standard cocultures. The model can be used to probe glia-neuron interactions and subsequently aid the development of assays for drug discovery, using neuronal excitability as a functional endpoint.
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Rupawala H, Shah K, Davies C, Rose J, Colom-Cadena M, Peng X, Granat L, Aljuhani M, Mizuno K, Troakes C, Perez-Nievas BG, Morgan A, So PW, Hortobagyi T, Spires-Jones TL, Noble W, Giese KP. Cysteine string protein alpha accumulates with early pre-synaptic dysfunction in Alzheimer’s disease. Brain Commun 2022; 4:fcac192. [PMID: 35928052 PMCID: PMC9345313 DOI: 10.1093/braincomms/fcac192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 05/12/2022] [Accepted: 07/20/2022] [Indexed: 11/17/2022] Open
Abstract
In Alzheimer’s disease, synapse loss causes memory and cognitive impairment. However, the mechanisms underlying synaptic degeneration in Alzheimer’s disease are not well understood. In the hippocampus, alterations in the level of cysteine string protein alpha, a molecular co-chaperone at the pre-synaptic terminal, occur prior to reductions in synaptophysin, suggesting that it is a very sensitive marker of synapse degeneration in Alzheimer’s. Here, we identify putative extracellular accumulations of cysteine string alpha protein, which are proximal to beta-amyloid deposits in post-mortem human Alzheimer’s brain and in the brain of a transgenic mouse model of Alzheimer’s disease. Cysteine string protein alpha, at least some of which is phosphorylated at serine 10, accumulates near the core of beta-amyloid deposits and does not co-localize with hyperphosphorylated tau, dystrophic neurites or glial cells. Using super-resolution microscopy and array tomography, cysteine string protein alpha was found to accumulate to a greater extent than other pre-synaptic proteins and at a comparatively great distance from the plaque core. This indicates that cysteine string protein alpha is most sensitive to being released from pre-synapses at low concentrations of beta-amyloid oligomers. Cysteine string protein alpha accumulations were also evident in other neurodegenerative diseases, including some fronto-temporal lobar dementias and Lewy body diseases, but only in the presence of amyloid plaques. Our findings are consistent with suggestions that pre-synapses are affected early in Alzheimer’s disease, and they demonstrate that cysteine string protein alpha is a more sensitive marker for early pre-synaptic dysfunction than traditional synaptic markers. We suggest that cysteine string protein alpha should be used as a pathological marker for early synaptic disruption caused by beta-amyloid.
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Affiliation(s)
- Huzefa Rupawala
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Keshvi Shah
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Caitlin Davies
- Centre for Discovery Brain Sciences and the UK Dementia Research Institute, The University of Edinburgh , 1 George Square, Edinburgh EH8 9JZ , UK
| | - Jamie Rose
- Centre for Discovery Brain Sciences and the UK Dementia Research Institute, The University of Edinburgh , 1 George Square, Edinburgh EH8 9JZ , UK
| | - Marti Colom-Cadena
- Centre for Discovery Brain Sciences and the UK Dementia Research Institute, The University of Edinburgh , 1 George Square, Edinburgh EH8 9JZ , UK
| | - Xianhui Peng
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Lucy Granat
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Manal Aljuhani
- Department of Neuroimaging, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Keiko Mizuno
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Claire Troakes
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Beatriz Gomez Perez-Nievas
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Alan Morgan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool , Liverpool L69 3BX , UK
| | - Po-Wah So
- Department of Neuroimaging, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Tibor Hortobagyi
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
- Department of Neurology, ELKH-DE Cerebrovascular and Neurodegenerative Research Group, University of Debrecen , 4032 Debrecen , Hungary
| | - Tara L Spires-Jones
- Centre for Discovery Brain Sciences and the UK Dementia Research Institute, The University of Edinburgh , 1 George Square, Edinburgh EH8 9JZ , UK
| | - Wendy Noble
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
| | - Karl Peter Giese
- Department of Basic and Clinical Neuroscience, King’s College London, Institute of Psychiatry, Psychology and Neuroscience , 5 Cutcombe Road, London SE5 9RX , UK
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Trecarichi A, Duggett NA, Granat L, Lo S, Malik AN, Zuliani-Álvarez L, Flatters SJL. Preclinical evidence for mitochondrial DNA as a potential blood biomarker for chemotherapy-induced peripheral neuropathy. PLoS One 2022; 17:e0262544. [PMID: 35015774 PMCID: PMC8752024 DOI: 10.1371/journal.pone.0262544] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/28/2021] [Indexed: 01/14/2023] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a serious dose-limiting side effect of several first-line chemotherapeutic agents including paclitaxel, oxaliplatin and bortezomib, for which no predictive marker is currently available. We have previously shown that mitochondrial dysfunction is associated with the development and maintenance of CIPN. The aim of this study was to evaluate the potential use of mitochondrial DNA (mtDNA) levels and complex I enzyme activity as blood biomarkers for CIPN. Real-time qPCR was used to measure mtDNA levels in whole blood collected from chemotherapy- and vehicle-treated rats at three key time-points of pain-like behaviour: prior to pain development, at the peak of mechanical hypersensitivity and at resolution of pain-like behaviour. Systemic oxaliplatin significantly increased mtDNA levels in whole blood prior to pain development. Furthermore, paclitaxel- and bortezomib-treated animals displayed significantly higher levels of mtDNA at the peak of mechanical hypersensitivity. Mitochondrial complex I activity in whole blood was assessed with an ELISA-based Complex I Enzyme Activity Dipstick Assay. Complex I activity was not altered by any of the three chemotherapeutic agents, either prior to or during pain-like behaviour. These data demonstrate that blood levels of mtDNA are altered after systemic administration of chemotherapy. Oxaliplatin, in particular, is associated with higher mtDNA levels before animals show any pain-like behaviour, thus suggesting a potential role for circulating mtDNA levels as non-invasive predictive biomarker for CIPN.
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Affiliation(s)
- Annalisa Trecarichi
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Natalie A. Duggett
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Lucy Granat
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Samantha Lo
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Afshan N. Malik
- Department of Diabetes, School of Life Course Sciences, King’s College London, London, United Kingdom
| | - Lorena Zuliani-Álvarez
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Sarah J. L. Flatters
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- * E-mail:
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Abstract
Neuronal mitochondrial dysfunction causes primary mitochondrial diseases and likely contributes to neurodegenerative diseases including Parkinson's and Alzheimer's disease. Mitochondrial dysfunction has also been documented in neurodevelopmental disorders such as tuberous sclerosis complex and autism spectrum disorder. Only symptomatic treatments exist for neurodevelopmental disorders, while neurodegenerative diseases are largely untreatable. Altered mitochondrial function activates mitochondrial retrograde signalling pathways, which enable signalling to the nucleus to reprogramme nuclear gene expression. In this review, we discuss the role of mitochondrial retrograde signalling in neurological diseases. We summarize how mitochondrial dysfunction contributes to neurodegenerative disease and neurodevelopmental disorders. Mitochondrial signalling mechanisms that have relevance to neurological disease are discussed. We then describe studies documenting retrograde signalling pathways in neurons and glia, and in animal models of neuronal mitochondrial dysfunction and neurological disease. Finally, we suggest how specific retrograde signalling pathways can be targeted to develop novel treatments for neurological diseases. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.
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Affiliation(s)
- Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 125 Coldharbour Lane, London SE5 9NU, UK
| | - Rachel J Hunt
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 125 Coldharbour Lane, London SE5 9NU, UK
| | - Joseph M Bateman
- Maurice Wohl Clinical Neuroscience Institute, King's College London, 125 Coldharbour Lane, London SE5 9NU, UK
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Hunt RJ, Granat L, McElroy GS, Ranganathan R, Chandel NS, Bateman JM. Mitochondrial stress causes neuronal dysfunction via an ATF4-dependent increase in L-2-hydroxyglutarate. J Cell Biol 2019; 218:4007-4016. [PMID: 31645461 PMCID: PMC6891100 DOI: 10.1083/jcb.201904148] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 08/19/2019] [Accepted: 09/11/2019] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial stress contributes to a range of neurological diseases. Mitonuclear signaling pathways triggered by mitochondrial stress remodel cellular physiology and metabolism. How these signaling mechanisms contribute to neuronal dysfunction and disease is poorly understood. We find that mitochondrial stress in neurons activates the transcription factor ATF4 as part of the endoplasmic reticulum unfolded protein response (UPR) in Drosophila We show that ATF4 activation reprograms nuclear gene expression and contributes to neuronal dysfunction. Mitochondrial stress causes an ATF4-dependent increase in the level of the metabolite L-2-hydroxyglutarate (L-2-HG) in the Drosophila brain. Reducing L-2-HG levels directly, by overexpressing L-2-HG dehydrogenase, improves neurological function. Modulation of L-2-HG levels by mitochondrial stress signaling therefore regulates neuronal function.
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Affiliation(s)
- Rachel J Hunt
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Gregory S McElroy
- Department of Medicine and Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Ramya Ranganathan
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
| | - Navdeep S Chandel
- Department of Medicine and Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Joseph M Bateman
- Maurice Wohl Clinical Neuroscience Institute, King's College London, London, UK
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Duncan OF, Granat L, Ranganathan R, Singh VK, Mazaud D, Fanto M, Chambers D, Ballard CG, Bateman JM. Ras-ERK-ETS inhibition alleviates neuronal mitochondrial dysfunction by reprogramming mitochondrial retrograde signaling. PLoS Genet 2018; 14:e1007567. [PMID: 30059502 PMCID: PMC6085068 DOI: 10.1371/journal.pgen.1007567] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 08/09/2018] [Accepted: 07/16/2018] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial dysfunction activates the mitochondrial retrograde signaling pathway, resulting in large scale changes in gene expression. Mitochondrial retrograde signaling in neurons is poorly understood and whether retrograde signaling contributes to cellular dysfunction or is protective is unknown. We show that inhibition of Ras-ERK-ETS signaling partially reverses the retrograde transcriptional response to alleviate neuronal mitochondrial dysfunction. We have developed a novel genetic screen to identify genes that modify mitochondrial dysfunction in Drosophila. Knock-down of one of the genes identified in this screen, the Ras-ERK-ETS pathway transcription factor Aop, alleviates the damaging effects of mitochondrial dysfunction in the nervous system. Inhibition of Ras-ERK-ETS signaling also restores function in Drosophila models of human diseases associated with mitochondrial dysfunction. Importantly, Ras-ERK-ETS pathway inhibition partially reverses the mitochondrial retrograde transcriptional response. Therefore, mitochondrial retrograde signaling likely contributes to neuronal dysfunction through mis-regulation of gene expression. Loss of mitochondrial function activates the mitochondrial retrograde signaling pathway resulting in large scale changes in nuclear gene transcription. Very little is known about retrograde signaling in the nervous system and how the transcriptional changes affect neuronal function. Here we identify Ras-ERK-ETS signaling as a novel mitochondrial retrograde signaling pathway in the Drosophila nervous system. Inhibition of Ras-ERK-ETS signaling improves neuronal function in Drosophila models of mitochondrial disease. Targeting Ras-ERK-ETS signaling may therefore have therapeutic potential in mitochondrial disease patients. Using a transcriptomic approach, we find that inhibition of Ras-ERK-ETS signaling partially reverses the mitochondrial retrograde transcriptional response. Surprisingly therefore, the mitochondrial retrograde transcriptional response contributes to neuronal dysfunction.
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Affiliation(s)
- Olivia F. Duncan
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Lucy Granat
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Ramya Ranganathan
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Vandana K. Singh
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - David Mazaud
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - Manolis Fanto
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
| | - David Chambers
- Wolfson Centre for Age-Related Diseases, King’s College London, London, United Kingdom
| | - Clive G. Ballard
- Medical School Building, St Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Joseph M. Bateman
- Maurice Wohl Clinical Neuroscience Institute, King’s College London, London, United Kingdom
- * E-mail:
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Granat L, Engström JE, Praveen S, Rodhe H. Light absorbing material (soot) in rainwater and in aerosol particles in the Maldives. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jd013768] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Gustafsson O, Krusa M, Zencak Z, Sheesley RJ, Granat L, Engstrom E, Praveen PS, Rao PSP, Leck C, Rodhe H. Brown Clouds over South Asia: Biomass or Fossil Fuel Combustion? Science 2009; 323:495-8. [DOI: 10.1126/science.1164857] [Citation(s) in RCA: 489] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Granat L, Hällgren JE. Relation between estimated dry deposition and throughfall in a coniferous forest exposed to controlled levels of SO2 and NO2. Environ Pollut 1992; 75:237-242. [PMID: 15092039 DOI: 10.1016/0269-7491(92)90045-c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Throughfall was collected in a Scots pine forest exposed to about 14 microg m(-3) of both SO2 and NO2, and in a control forest with 1 microg m(-3) SO2 and < 1 microg m(-3) NO2. Precipitation was collected in a nearby open field. Collection was performed on an event basis during the whole vegetation period. Exposure was made by an open-air release system during the vegetation period, except during rain and at night. Additional sulfate deposition in the exposed forest (compared to control forest) was nearly equal to dry deposition of sulfur dioxide, as estimated with a stomatal conductance model adapted for the particular forest. It is thus concluded that essentially all of the dry deposited sulfur dioxide is eventually extracted and appears in throughfall-including the fraction that has been deposited through stomata. Attempts to relate net throughfall deposition to dry deposition of sulfate in the control forest were inconclusive, since a minor (10%) uncertainty in the water balance had a major influence on calculated deposition velocity for particulate sulfate. Nitrate throughfall deposition is about half of the open field wet deposition, both for the exposed and control forest. Thus, a long-term exposure with about 14 microg m(-3) NO2 decreased nitrate throughfall deposition.
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Affiliation(s)
- L Granat
- Department of Meteorology, University of Stockholm, Arrhenius Laboratory S-10691 Stockholm, Sweden
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Lannefors H, Hansson HC, Granat L. Background aerosol composition in Southern Sweden—Fourteen micro and macro constituents measured in seven particle size intervals at one site during one year. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/0004-6981(83)90012-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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