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Ilaria S, Tamara D, Antonella DJ, Elena M. Role of mitochondria-endoplasmic reticulum contacts in neurodegenerative, neurodevelopmental and neuropsychiatric conditions. Eur J Neurosci 2024. [PMID: 39099373 DOI: 10.1111/ejn.16485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 04/15/2024] [Accepted: 07/15/2024] [Indexed: 08/06/2024]
Abstract
Mitochondria-endoplasmic reticulum contacts (MERCs) mediate a close and continuous communication between both organelles that is essential for the transfer of calcium and lipids to mitochondria, necessary for cellular signalling and metabolic pathways. Their structural and molecular characterisation has shown the involvement of many proteins that bridge the membranes of the two organelles and maintain the structural stability and function of these contacts. The crosstalk between the two organelles is fundamental for proper neuronal function and is now recognised as a component of many neurological disorders. In fact, an increasing proportion of MERC proteins take part in the molecular and cellular basis of pathologies affecting the nervous system. Here we review the alterations in MERCs that have been reported for these pathologies, from neurodevelopmental and neuropsychiatric disorders to neurodegenerative diseases. Although mitochondrial abnormalities in these debilitating conditions have been extensively attributed to the high energy demand of neurons, a distinct role for MERCs is emerging as a new field of research. Understanding the molecular details of such alterations may open the way to new paths of therapeutic intervention.
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Affiliation(s)
- Serangeli Ilaria
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy
| | - Diamanti Tamara
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy
| | - De Jaco Antonella
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy
| | - Miranda Elena
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy
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2
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Licini C, Morroni G, Lucarini G, Vitto VAM, Orlando F, Missiroli S, D'Achille G, Perrone M, Spadoni T, Graciotti L, Bigossi G, Provinciali M, Offidani A, Mattioli-Belmonte M, Cirioni O, Pinton P, Simonetti O, Marchi S. ER-mitochondria association negatively affects wound healing by regulating NLRP3 activation. Cell Death Dis 2024; 15:407. [PMID: 38862500 PMCID: PMC11167056 DOI: 10.1038/s41419-024-06765-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/14/2024] [Accepted: 05/21/2024] [Indexed: 06/13/2024]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative agent of acute bacterial skin and skin-structure infections (ABSSSI), one of the major challenges to the health system worldwide. Although the use of antibiotics as the first line of intervention for MRSA-infected wounds is recommended, important side effects could occur, including cytotoxicity or immune dysregulation, thus affecting the repair process. Here, we show that the oxazolidinone antibiotic linezolid (LZD) impairs wound healing by aberrantly increasing interleukin 1 β (IL-1β) production in keratinocytes. Mechanistically, LZD triggers a reactive oxygen species (ROS)-independent mitochondrial damage that culminates in increased tethering between the endoplasmic reticulum (ER) and mitochondria, which in turn activates the NLR family pyrin domain-containing 3 (NLRP3) inflammasome complex by promoting its assembly to the mitochondrial surface. Downregulation of ER-mitochondria contact formation is sufficient to inhibit the LZD-driven NLRP3 inflammasome activation and IL-1β production, restoring wound closure. These results identify the ER-mitochondria association as a key factor for NLRP3 activation and reveal a new mechanism in the regulation of the wound healing process that might be clinically relevant.
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Affiliation(s)
- Caterina Licini
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
| | - Gianluca Morroni
- Microbiology Unit, Department of Biomedical Sciences and Public Health, Marche Polytechnic University, Ancona, Italy
| | - Guendalina Lucarini
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
| | - Veronica Angela Maria Vitto
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Fiorenza Orlando
- Experimental Animal Models for Aging Research, Scientific Technological Area, IRCCS INRCA, 60121, Ancona, Italy
| | - Sonia Missiroli
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Gloria D'Achille
- Microbiology Unit, Department of Biomedical Sciences and Public Health, Marche Polytechnic University, Ancona, Italy
| | - Mariasole Perrone
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Tatiana Spadoni
- Department of Biomedical Sciences and Public Health, Marche Polytechnic University, Ancona, Italy
| | - Laura Graciotti
- Department of Biomedical Sciences and Public Health, Marche Polytechnic University, Ancona, Italy
| | - Giorgia Bigossi
- Advanced Technology Center for Aging Research, IRCCS INRCA, 60121, Ancona, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, IRCCS INRCA, 60121, Ancona, Italy
| | - Annamaria Offidani
- Clinic of Dermatology, Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
| | - Monica Mattioli-Belmonte
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
- Advanced Technology Center for Aging Research, IRCCS INRCA, 60121, Ancona, Italy
| | - Oscar Cirioni
- Clinic of Infectious Diseases, Department of Biomedical Sciences and Public Health, Marche Polytechnic University, Ancona, Italy
| | - Paolo Pinton
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Oriana Simonetti
- Clinic of Dermatology, Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy.
| | - Saverio Marchi
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy.
- Advanced Technology Center for Aging Research, IRCCS INRCA, 60121, Ancona, Italy.
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Nakamura K, Aoyama-Ishiwatari S, Nagao T, Paaran M, Obara CJ, Sakurai-Saito Y, Johnston J, Du Y, Suga S, Tsuboi M, Nakakido M, Tsumoto K, Kishi Y, Gotoh Y, Kwak C, Rhee HW, Seo JK, Kosako H, Potter C, Carragher B, Lippincott-Schwartz J, Polleux F, Hirabayashi Y. PDZD8-FKBP8 tethering complex at ER-mitochondria contact sites regulates mitochondrial complexity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.22.554218. [PMID: 38895210 PMCID: PMC11185567 DOI: 10.1101/2023.08.22.554218] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Mitochondria-ER membrane contact sites (MERCS) represent a fundamental ultrastructural feature underlying unique biochemistry and physiology in eukaryotic cells. The ER protein PDZD8 is required for the formation of MERCS in many cell types, however, its tethering partner on the outer mitochondrial membrane (OMM) is currently unknown. Here we identified the OMM protein FKBP8 as the tethering partner of PDZD8 using a combination of unbiased proximity proteomics, CRISPR-Cas9 endogenous protein tagging, Cryo-Electron Microscopy (Cryo-EM) tomography, and correlative light-EM (CLEM). Single molecule tracking revealed highly dynamic diffusion properties of PDZD8 along the ER membrane with significant pauses and capture at MERCS. Overexpression of FKBP8 was sufficient to narrow the ER-OMM distance, whereas independent versus combined deletions of these two proteins demonstrated their interdependence for MERCS formation. Furthermore, PDZD8 enhances mitochondrial complexity in a FKBP8-dependent manner. Our results identify a novel ER-mitochondria tethering complex that regulates mitochondrial morphology in mammalian cells.
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Lee J, Pye N, Ellis L, Vos KD, Mortiboys H. Evidence of mitochondrial dysfunction in ALS and methods for measuring in model systems. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 176:269-325. [PMID: 38802177 DOI: 10.1016/bs.irn.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Metabolic dysfunction is a hallmark of multiple amyotrophic lateral sclerosis (ALS) models with a majority of ALS patients exhibiting hypermetabolism. The central sites of metabolism in the cell are mitochondria, capable of utilising a multitude of cellular substrates in an array of ATP-generating reactions. With reactive oxygen species (ROS) production occurring during some of these reactions, mitochondria can contribute considerably to oxidative stress. Mitochondria are also very dynamic organelles, interacting with other organelles, undergoing fusion/fission in response to changing metabolic states and being turned over by the cell regularly. Disruptions to many of these mitochondrial functions and processes have been reported in ALS models, largely indicating compromised mitochondrial function, increased ROS production by mitochondria, disrupted interactions with the endoplasmic reticulum and reduced turnover. This chapter summarises methods routinely used to assess mitochondria in ALS models and the alterations that have been reported in these models.
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Affiliation(s)
- James Lee
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom
| | - Natalie Pye
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom
| | - Laura Ellis
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom
| | - Kurt De Vos
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom
| | - Heather Mortiboys
- Sheffield Institute for Translational Neuroscience, School of Medicine and Population Health, University of Sheffield, Sheffield, United Kingdom.
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5
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Wang Y, Yang J. ER-organelle contacts: A signaling hub for neurological diseases. Pharmacol Res 2024; 203:107149. [PMID: 38518830 DOI: 10.1016/j.phrs.2024.107149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/07/2024] [Accepted: 03/19/2024] [Indexed: 03/24/2024]
Abstract
Neuronal health is closely linked to the homeostasis of intracellular organelles, and organelle dysfunction affects the pathological progression of neurological diseases. In contrast to isolated cellular compartments, a growing number of studies have found that organelles are largely interdependent structures capable of communicating through membrane contact sites (MCSs). MCSs have been identified as key pathways mediating inter-organelle communication crosstalk in neurons, and their alterations have been linked to neurological disease pathology. The endoplasmic reticulum (ER) is a membrane-bound organelle capable of forming an extensive network of pools and tubules with important physiological functions within neurons. There are multiple MCSs between the ER and other organelles and the plasma membrane (PM), which regulate a variety of cellular processes. In this review, we focus on ER-organelle MCSs and their role in a variety of neurological diseases. We compared the biological effects between different tethering proteins and the effects of their respective disease counterparts. We also discuss how altered ER-organelle contacts may affect disease pathogenesis. Therefore, understanding the molecular mechanisms of ER-organelle MCSs in neuronal homeostasis will lay the foundation for the development of new therapies targeting ER-organelle contacts.
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Affiliation(s)
- Yunli Wang
- Key Laboratory of Environmental Stress and Chronic Disease Control & Prevention (China Medical University), Ministry of Education, PR China; Department of Toxicology, School of Public Health, China Medical University, Shenyang 110122, PR China
| | - Jinghua Yang
- Key Laboratory of Environmental Stress and Chronic Disease Control & Prevention (China Medical University), Ministry of Education, PR China; Department of Toxicology, School of Public Health, China Medical University, Shenyang 110122, PR China.
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Wilson EL, Yu Y, Leal NS, Woodward JA, Patikas N, Morris JL, Field SF, Plumbly W, Paupe V, Chowdhury SR, Antrobus R, Lindop GE, Adia YM, Loh SHY, Prudent J, Martins LM, Metzakopian E. Genome-wide CRISPR/Cas9 screen shows that loss of GET4 increases mitochondria-endoplasmic reticulum contact sites and is neuroprotective. Cell Death Dis 2024; 15:203. [PMID: 38467609 PMCID: PMC10928201 DOI: 10.1038/s41419-024-06568-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 02/13/2024] [Accepted: 02/19/2024] [Indexed: 03/13/2024]
Abstract
Organelles form membrane contact sites between each other, allowing for the transfer of molecules and signals. Mitochondria-endoplasmic reticulum (ER) contact sites (MERCS) are cellular subdomains characterized by close apposition of mitochondria and ER membranes. They have been implicated in many diseases, including neurodegenerative, metabolic, and cardiac diseases. Although MERCS have been extensively studied, much remains to be explored. To uncover novel regulators of MERCS, we conducted a genome-wide, flow cytometry-based screen using an engineered MERCS reporter cell line. We found 410 genes whose downregulation promotes MERCS and 230 genes whose downregulation decreases MERCS. From these, 29 genes were selected from each population for arrayed screening and 25 were validated from the high population and 13 from the low population. GET4 and BAG6 were highlighted as the top 2 genes that upon suppression increased MERCS from both the pooled and arrayed screens, and these were subjected to further investigation. Multiple microscopy analyses confirmed that loss of GET4 or BAG6 increased MERCS. GET4 and BAG6 were also observed to interact with the known MERCS proteins, inositol 1,4,5-trisphosphate receptors (IP3R) and glucose-regulated protein 75 (GRP75). In addition, we found that loss of GET4 increased mitochondrial calcium uptake upon ER-Ca2+ release and mitochondrial respiration. Finally, we show that loss of GET4 rescues motor ability, improves lifespan and prevents neurodegeneration in a Drosophila model of Alzheimer's disease (Aβ42Arc). Together, these results suggest that GET4 is involved in decreasing MERCS and that its loss is neuroprotective.
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Affiliation(s)
- Emma L Wilson
- UK Dementia Research Institute, University of Cambridge, Clifford Albutt building, Cambridge biomedical campus, Cambridge, CB2 0AH, UK
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters building, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Yizhou Yu
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Nuno S Leal
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - James A Woodward
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Nikolaos Patikas
- UK Dementia Research Institute, University of Cambridge, Clifford Albutt building, Cambridge biomedical campus, Cambridge, CB2 0AH, UK
| | - Jordan L Morris
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters building, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Sarah F Field
- UK Dementia Research Institute, University of Cambridge, Clifford Albutt building, Cambridge biomedical campus, Cambridge, CB2 0AH, UK
| | - William Plumbly
- UK Dementia Research Institute, University of Cambridge, Clifford Albutt building, Cambridge biomedical campus, Cambridge, CB2 0AH, UK
| | - Vincent Paupe
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters building, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Suvagata R Chowdhury
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters building, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Rd, Cambridge, CB2 0XY, UK
| | - Georgina E Lindop
- Cambridge Advanced Imaging Centre, University of Cambridge, Anatomy Building, Downing Site, Cambridge, CB2 3DY, UK
| | - Yusuf M Adia
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Samantha H Y Loh
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Julien Prudent
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters building, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
| | - L Miguel Martins
- MRC Toxicology Unit, University of Cambridge, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK.
| | - Emmanouil Metzakopian
- UK Dementia Research Institute, University of Cambridge, Clifford Albutt building, Cambridge biomedical campus, Cambridge, CB2 0AH, UK.
- bit bio, The Dorothy Hodgkin Building, Babraham Research Campus, Cambridge, CB22 3FH, UK.
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7
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Twyning MJ, Tufi R, Gleeson TP, Kolodziej KM, Campesan S, Terriente-Felix A, Collins L, De Lazzari F, Giorgini F, Whitworth AJ. Partial loss of MCU mitigates pathology in vivo across a diverse range of neurodegenerative disease models. Cell Rep 2024; 43:113681. [PMID: 38236772 DOI: 10.1016/j.celrep.2024.113681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 11/01/2023] [Accepted: 01/02/2024] [Indexed: 03/02/2024] Open
Abstract
Mitochondrial calcium (Ca2+) uptake augments metabolic processes and buffers cytosolic Ca2+ levels; however, excessive mitochondrial Ca2+ can cause cell death. Disrupted mitochondrial function and Ca2+ homeostasis are linked to numerous neurodegenerative diseases (NDs), but the impact of mitochondrial Ca2+ disruption is not well understood. Here, we show that Drosophila models of multiple NDs (Parkinson's, Huntington's, Alzheimer's, and frontotemporal dementia) reveal a consistent increase in neuronal mitochondrial Ca2+ levels, as well as reduced mitochondrial Ca2+ buffering capacity, associated with increased mitochondria-endoplasmic reticulum contact sites (MERCs). Importantly, loss of the mitochondrial Ca2+ uptake channel MCU or overexpression of the efflux channel NCLX robustly suppresses key pathological phenotypes across these ND models. Thus, mitochondrial Ca2+ imbalance is a common feature of diverse NDs in vivo and is an important contributor to the disease pathogenesis. The broad beneficial effects from partial loss of MCU across these models presents a common, druggable target for therapeutic intervention.
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Affiliation(s)
- Madeleine J Twyning
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Roberta Tufi
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Thomas P Gleeson
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Kinga M Kolodziej
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Susanna Campesan
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Ana Terriente-Felix
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Lewis Collins
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Federica De Lazzari
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - Flaviano Giorgini
- Department of Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
| | - Alexander J Whitworth
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK.
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Makio T, Simmen T. Not So Rare: Diseases Based on Mutant Proteins Controlling Endoplasmic Reticulum-Mitochondria Contact (MERC) Tethering. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2024; 7:25152564241261228. [PMID: 39070058 PMCID: PMC11273598 DOI: 10.1177/25152564241261228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 04/12/2024] [Accepted: 05/27/2024] [Indexed: 07/30/2024]
Abstract
Mitochondria-endoplasmic reticulum contacts (MERCs), also called endoplasmic reticulum (ER)-mitochondria contact sites (ERMCS), are the membrane domains, where these two organelles exchange lipids, Ca2+ ions, and reactive oxygen species. This crosstalk is a major determinant of cell metabolism, since it allows the ER to control mitochondrial oxidative phosphorylation and the Krebs cycle, while conversely, it allows the mitochondria to provide sufficient ATP to control ER proteostasis. MERC metabolic signaling is under the control of tethers and a multitude of regulatory proteins. Many of these proteins have recently been discovered to give rise to rare diseases if their genes are mutated. Surprisingly, these diseases share important hallmarks and cause neurological defects, sometimes paired with, or replaced by skeletal muscle deficiency. Typical symptoms include developmental delay, intellectual disability, facial dysmorphism and ophthalmologic defects. Seizures, epilepsy, deafness, ataxia, or peripheral neuropathy can also occur upon mutation of a MERC protein. Given that most MERC tethers and regulatory proteins have secondary functions, some MERC protein-based diseases do not fit into this categorization. Typically, however, the proteins affected in those diseases have dominant functions unrelated to their roles in MERCs tethering or their regulation. We are discussing avenues to pharmacologically target genetic diseases leading to MERC defects, based on our novel insight that MERC defects lead to common characteristics in rare diseases. These shared characteristics of MERCs disorders raise the hope that they may allow for similar treatment options.
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Affiliation(s)
- Tadashi Makio
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Thomas Simmen
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Thakur RS, O’Connor-Giles KM. PDZD8 promotes autophagy at ER-Lysosome contact sites to regulate synaptogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.30.564828. [PMID: 37961523 PMCID: PMC10634952 DOI: 10.1101/2023.10.30.564828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Building synaptic connections, which are often far from the soma, requires coordinating a host of cellular activities from transcription to protein turnover, placing a high demand on intracellular communication. Membrane contact sites (MCSs) formed between cellular organelles have emerged as key signaling hubs for coordinating an array of cellular activities. We have found that the endoplasmic reticulum (ER) MCS tethering protein PDZD8 is required for activity-dependent synaptogenesis. PDZD8 is sufficient to drive ectopic synaptic bouton formation through an autophagy-dependent mechanism and required for basal synapse formation when autophagy biogenesis is limited. PDZD8 functions at ER-late endosome/lysosome (LEL) MCSs to promote lysosome maturation and accelerate autophagic flux. Mutational analysis of PDZD8's SMP domain further suggests a role for lipid transfer at ER-LEL MCSs. We propose that PDZD8-dependent lipid transfer from ER to LELs promotes lysosome maturation to increase autophagic flux during periods of high demand, including activity-dependent synapse formation.
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Affiliation(s)
- Rajan S. Thakur
- Department of Neuroscience, Brown University, Providence, RI
| | - Kate M. O’Connor-Giles
- Department of Neuroscience, Brown University, Providence, RI
- Carney Institute for Brain Science, Providence, RI
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10
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Maddison DC, Malik B, Amadio L, Bis-Brewer DM, Züchner S, Peters OM, Smith GA. COPI-regulated mitochondria-ER contact site formation maintains axonal integrity. Cell Rep 2023; 42:112883. [PMID: 37498742 PMCID: PMC10840514 DOI: 10.1016/j.celrep.2023.112883] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 06/05/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023] Open
Abstract
Coat protein complex I (COPI) is best known for its role in Golgi-endoplasmic reticulum (ER) trafficking, responsible for the retrograde transport of ER-resident proteins. The ER is crucial to neuronal function, regulating Ca2+ homeostasis and the distribution and function of other organelles such as endosomes, peroxisomes, and mitochondria via functional contact sites. Here we demonstrate that disruption of COPI results in mitochondrial dysfunction in Drosophila axons and human cells. The ER network is also disrupted, and the neurons undergo rapid degeneration. We demonstrate that mitochondria-ER contact sites (MERCS) are decreased in COPI-deficient axons, leading to Ca2+ dysregulation, heightened mitophagy, and a decrease in respiratory capacity. Reintroducing MERCS is sufficient to rescue not only mitochondrial distribution and Ca2+ uptake but also ER morphology, dramatically delaying neurodegeneration. This work demonstrates an important role for COPI-mediated trafficking in MERC formation, which is an essential process for maintaining axonal integrity.
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Affiliation(s)
- Daniel C Maddison
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Bilal Malik
- UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Leonardo Amadio
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK; UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Dana M Bis-Brewer
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Stephan Züchner
- John P. Hussman Institute for Human Genomics, University of Miami, Miami, FL, USA; Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Miami, FL, USA
| | - Owen M Peters
- UK Dementia Research Institute, School of Biosciences, Cardiff University, Cardiff CF24 4HQ, UK
| | - Gaynor A Smith
- UK Dementia Research Institute, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK.
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11
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Mattedi F, Lloyd-Morris E, Hirth F, Vagnoni A. Optogenetic cleavage of the Miro GTPase reveals the direct consequences of real-time loss of function in Drosophila. PLoS Biol 2023; 21:e3002273. [PMID: 37590319 PMCID: PMC10465005 DOI: 10.1371/journal.pbio.3002273] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 08/29/2023] [Accepted: 07/22/2023] [Indexed: 08/19/2023] Open
Abstract
Miro GTPases control mitochondrial morphology, calcium homeostasis, and regulate mitochondrial distribution by mediating their attachment to the kinesin and dynein motor complex. It is not clear, however, how Miro proteins spatially and temporally integrate their function as acute disruption of protein function has not been performed. To address this issue, we have developed an optogenetic loss of function "Split-Miro" allele for precise control of Miro-dependent mitochondrial functions in Drosophila. Rapid optogenetic cleavage of Split-Miro leads to a striking rearrangement of the mitochondrial network, which is mediated by mitochondrial interaction with the microtubules. Unexpectedly, this treatment did not impact the ability of mitochondria to buffer calcium or their association with the endoplasmic reticulum. While Split-Miro overexpression is sufficient to augment mitochondrial motility, sustained photocleavage shows that Split-Miro is surprisingly dispensable to maintain elevated mitochondrial processivity. In adult fly neurons in vivo, Split-Miro photocleavage affects both mitochondrial trafficking and neuronal activity. Furthermore, functional replacement of endogenous Miro with Split-Miro identifies its essential role in the regulation of locomotor activity in adult flies, demonstrating the feasibility of tuning animal behaviour by real-time loss of protein function.
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Affiliation(s)
- Francesca Mattedi
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Ethlyn Lloyd-Morris
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Frank Hirth
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Alessio Vagnoni
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
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Rühmkorf A, Harbauer AB. Role of Mitochondria-ER Contact Sites in Mitophagy. Biomolecules 2023; 13:1198. [PMID: 37627263 PMCID: PMC10452924 DOI: 10.3390/biom13081198] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/27/2023] Open
Abstract
Mitochondria are often referred to as the "powerhouse" of the cell. However, this organelle has many more functions than simply satisfying the cells' metabolic needs. Mitochondria are involved in calcium homeostasis and lipid metabolism, and they also regulate apoptotic processes. Many of these functions require contact with the ER, which is mediated by several tether proteins located on the respective organellar surfaces, enabling the formation of mitochondria-ER contact sites (MERCS). Upon damage, mitochondria produce reactive oxygen species (ROS) that can harm the surrounding cell. To circumvent toxicity and to maintain a functional pool of healthy organelles, damaged and excess mitochondria can be targeted for degradation via mitophagy, a form of selective autophagy. Defects in mitochondria-ER tethers and the accumulation of damaged mitochondria are found in several neurodegenerative diseases, including Parkinson's disease and amyotrophic lateral sclerosis, which argues that the interplay between the two organelles is vital for neuronal health. This review provides an overview of the different mechanisms of mitochondrial quality control that are implicated with the different mitochondria-ER tether proteins, and also provides a novel perspective on how MERCS are involved in mediating mitophagy upon mitochondrial damage.
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Affiliation(s)
- Alina Rühmkorf
- TUM Medical Graduate Center, Technical University of Munich, 81675 Munich, Germany
- Max Planck Institute for Biological Intelligence, 82152 Planegg-Martinsried, Germany
| | - Angelika Bettina Harbauer
- Max Planck Institute for Biological Intelligence, 82152 Planegg-Martinsried, Germany
- Institute of Neuronal Cell Biology, Technical University of Munich, 80802 Munich, Germany
- Munich Cluster for Systems Neurology, 81377 Munich, Germany
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13
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Smith G, Sweeney ST, O’Kane CJ, Prokop A. How neurons maintain their axons long-term: an integrated view of axon biology and pathology. Front Neurosci 2023; 17:1236815. [PMID: 37564364 PMCID: PMC10410161 DOI: 10.3389/fnins.2023.1236815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
Axons are processes of neurons, up to a metre long, that form the essential biological cables wiring nervous systems. They must survive, often far away from their cell bodies and up to a century in humans. This requires self-sufficient cell biology including structural proteins, organelles, and membrane trafficking, metabolic, signalling, translational, chaperone, and degradation machinery-all maintaining the homeostasis of energy, lipids, proteins, and signalling networks including reactive oxygen species and calcium. Axon maintenance also involves specialised cytoskeleton including the cortical actin-spectrin corset, and bundles of microtubules that provide the highways for motor-driven transport of components and organelles for virtually all the above-mentioned processes. Here, we aim to provide a conceptual overview of key aspects of axon biology and physiology, and the homeostatic networks they form. This homeostasis can be derailed, causing axonopathies through processes of ageing, trauma, poisoning, inflammation or genetic mutations. To illustrate which malfunctions of organelles or cell biological processes can lead to axonopathies, we focus on axonopathy-linked subcellular defects caused by genetic mutations. Based on these descriptions and backed up by our comprehensive data mining of genes linked to neural disorders, we describe the 'dependency cycle of local axon homeostasis' as an integrative model to explain why very different causes can trigger very similar axonopathies, providing new ideas that can drive the quest for strategies able to battle these devastating diseases.
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Affiliation(s)
- Gaynor Smith
- Cardiff University, School of Medicine, College of Biomedical and Life Sciences, Cardiff, United Kingdom
| | - Sean T. Sweeney
- Department of Biology, University of York and York Biomedical Research Institute, York, United Kingdom
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, The University of Manchester, Manchester, United Kingdom
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14
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Garcia-Casas P, Rossini M, Filadi R, Pizzo P. Mitochondrial Ca 2+ signaling and Alzheimer's disease: Too much or too little? Cell Calcium 2023; 113:102757. [PMID: 37192560 DOI: 10.1016/j.ceca.2023.102757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 05/18/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease, caused by poorly known pathogenic mechanisms and aggravated by delayed therapeutic intervention, that still lacks an effective cure. However, it is clear that some important neurophysiological processes are altered years before the onset of clinical symptoms, offering the possibility of identifying biological targets useful for implementation of new therapies. Of note, evidence has been provided suggesting that mitochondria, pivotal organelles in sustaining neuronal energy demand and modulating synaptic activity, are dysfunctional in AD samples. In particular, alterations in mitochondrial Ca2+ signaling have been proposed as causal events for neurodegeneration, although the exact outcomes and molecular mechanisms of these defects, as well as their longitudinal progression, are not always clear. Here, we discuss the importance of a correct mitochondrial Ca2+ handling for neuronal physiology and summarize the latest findings on dysfunctional mitochondrial Ca2+ pathways in AD, analysing possible consequences contributing to the neurodegeneration that characterizes the disease.
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Affiliation(s)
- Paloma Garcia-Casas
- Department of Biomedical Sciences, University of Padova, 35131 Padua, Italy; Department of Biochemistry and Molecular Biology and Physiology, School of Medicine, University of Valladolid, 47003 Valladolid, Spain
| | - Michela Rossini
- Department of Biomedical Sciences, University of Padova, 35131 Padua, Italy
| | - Riccardo Filadi
- Department of Biomedical Sciences, University of Padova, 35131 Padua, Italy; Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy.
| | - Paola Pizzo
- Department of Biomedical Sciences, University of Padova, 35131 Padua, Italy; Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; Study Centre for Neurodegeneration (CESNE), University of Padova, 35131 Padua, Italy.
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15
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de Ridder I, Kerkhofs M, Lemos FO, Loncke J, Bultynck G, Parys JB. The ER-mitochondria interface, where Ca 2+ and cell death meet. Cell Calcium 2023; 112:102743. [PMID: 37126911 DOI: 10.1016/j.ceca.2023.102743] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 04/20/2023] [Accepted: 04/24/2023] [Indexed: 05/03/2023]
Abstract
Endoplasmic reticulum (ER)-mitochondria contact sites are crucial to allow Ca2+ flux between them and a plethora of proteins participate in tethering both organelles together. Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a pivotal role at such contact sites, participating in both ER-mitochondria tethering and as Ca2+-transport system that delivers Ca2+ from the ER towards mitochondria. At the ER-mitochondria contact sites, the IP3Rs function as a multi-protein complex linked to the voltage-dependent anion channel 1 (VDAC1) in the outer mitochondrial membrane, via the chaperone glucose-regulated protein 75 (GRP75). This IP3R-GRP75-VDAC1 complex supports the efficient transfer of Ca2+ from the ER into the mitochondrial intermembrane space, from which the Ca2+ ions can reach the mitochondrial matrix through the mitochondrial calcium uniporter. Under physiological conditions, basal Ca2+ oscillations deliver Ca2+ to the mitochondrial matrix, thereby stimulating mitochondrial oxidative metabolism. However, when mitochondrial Ca2+ overload occurs, the increase in [Ca2+] will induce the opening of the mitochondrial permeability transition pore, thereby provoking cell death. The IP3R-GRP75-VDAC1 complex forms a hub for several other proteins that stabilize the complex and/or regulate the complex's ability to channel Ca2+ into the mitochondria. These proteins and their mechanisms of action are discussed in the present review with special attention for their role in pathological conditions and potential implication for therapeutic strategies.
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Affiliation(s)
- Ian de Ridder
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Martijn Kerkhofs
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Fernanda O Lemos
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Jens Loncke
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium
| | - Geert Bultynck
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium.
| | - Jan B Parys
- KU Leuven, Laboratory for Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Campus Gasthuisberg O/N-1 B-802, Herestraat 49, Leuven BE-3000, Belgium.
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Varte V, Munkelwitz JW, Rincon-Limas DE. Insights from Drosophila on Aβ- and tau-induced mitochondrial dysfunction: mechanisms and tools. Front Neurosci 2023; 17:1184080. [PMID: 37139514 PMCID: PMC10150963 DOI: 10.3389/fnins.2023.1184080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 03/31/2023] [Indexed: 05/05/2023] Open
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative dementia in older adults worldwide. Sadly, there are no disease-modifying therapies available for treatment due to the multifactorial complexity of the disease. AD is pathologically characterized by extracellular deposition of amyloid beta (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. Increasing evidence suggest that Aβ also accumulates intracellularly, which may contribute to the pathological mitochondrial dysfunction observed in AD. According with the mitochondrial cascade hypothesis, mitochondrial dysfunction precedes clinical decline and thus targeting mitochondria may result in new therapeutic strategies. Unfortunately, the precise mechanisms connecting mitochondrial dysfunction with AD are largely unknown. In this review, we will discuss how the fruit fly Drosophila melanogaster is contributing to answer mechanistic questions in the field, from mitochondrial oxidative stress and calcium dysregulation to mitophagy and mitochondrial fusion and fission. In particular, we will highlight specific mitochondrial insults caused by Aβ and tau in transgenic flies and will also discuss a variety of genetic tools and sensors available to study mitochondrial biology in this flexible organism. Areas of opportunity and future directions will be also considered.
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Affiliation(s)
- Vanlalrinchhani Varte
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States
| | - Jeremy W. Munkelwitz
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States
| | - Diego E. Rincon-Limas
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, United States
- Department of Neuroscience, University of Florida, Gainesville, FL, United States
- Genetics Institute, University of Florida, Gainesville, FL, United States
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17
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New discoveries in ER-mitochondria communication. Biochem Soc Trans 2023; 51:571-577. [PMID: 36892405 DOI: 10.1042/bst20221305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/17/2023] [Accepted: 02/17/2023] [Indexed: 03/10/2023]
Abstract
The study of endoplasmic reticulum (ER)-mitochondria communication is a vast and expanding field with many novel developments in the past few years. In this mini-review, we focus on several recent publications that identify novel functions of tether complexes, in particular autophagy regulation and lipid droplet biogenesis. We review novel findings that shed light on the role of triple contacts between ER and mitochondria with peroxisomes or lipid droplets as the third player. We also summarize recent findings on the role of ER-mitochondria contacts in human neurodegenerative diseases, which implicate either enhanced or reduced ER-mitochondria contacts in neurodegeneration. Taken together, the discussed studies highlight the need for further research into the role of triple organelle contacts, as well as into the exact mechanisms of increased and decreased ER-mitochondria contacts in neurodegeneration.
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Kim YK, Jung YS, Song J. Transcriptome Profile in the Mouse Brain of Hepatic Encephalopathy and Alzheimer's Disease. Int J Mol Sci 2022; 24:ijms24010675. [PMID: 36614117 PMCID: PMC9821016 DOI: 10.3390/ijms24010675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 01/03/2023] Open
Abstract
Hepatic encephalopathy (HE) is a chronic metabolic disease accompanied by neuropathological and neuropsychiatric features, including memory deficits, psychomotor dysfunction, depression, and anxiety. Alzheimer's disease (AD), the most common neurodegenerative disease, is characterized by tau hyperphosphorylation, excessive amyloid beta (Aβ) accumulation, the formation of fibrillary tangles, hippocampus atrophy, and neuroinflammation. Recent studies have suggested a positive correlation between HE and AD. Some studies reported that an impaired cholesterol pathway, abnormal bile acid secretion, excessive ammonia level, impaired Aβ clearance, astrocytic dysfunction, and abnormal γ-aminobutyric acid GABAergic neuronal signaling in HE may also be involved in AD pathology. However, the mechanisms and related genes involved in AD-like pathology in the HE brain are unclear. Thus, we compared the cortical transcriptome profile between an HE mouse model, bile duct ligation (BDL), and an AD mouse model, the 5×FAD. Our study showed that the expression of many genes implicated in HE is associated with neuronal dysfunction in AD mice. We found changes in various protein-coding RNAs, implicated in synapses, neurogenesis, neuron projection, neuron differentiation, and neurite outgrowth, and non-coding RNAs possibly associated with neuropathology. Our data provide an important resource for further studies to elucidate AD-like pathophysiology in HE patients.
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Affiliation(s)
- Young-Kook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
| | - Yoon Seok Jung
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Republic of Korea
- Correspondence: ; Tel.: +82-61-379-2706; Fax: +82-61-375-5834
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1-L Transcription in Alzheimer's Disease. Curr Issues Mol Biol 2022; 44:3533-3551. [PMID: 36005139 PMCID: PMC9406503 DOI: 10.3390/cimb44080243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/04/2022] [Accepted: 08/06/2022] [Indexed: 11/23/2022] Open
Abstract
Alzheimer’s disease is a very complex disease and better explanations and models are needed to understand how neurons are affected and microglia are activated. A new model of Alzheimer’s disease is presented here, the β-amyloid peptide is considered an important RNA recognition/binding peptide. 1-L transcription revealed compatible sequences with AAUAAA (PAS signal) and UUUC (class III ARE rich in U) in the Aβ peptide, supporting the peptide–RNA regulatory model. When a hypothetical model of fibril selection with the prionic character of amyloid assemblies is added to the peptide-RNA regulatory model, the downregulation of the PI3K-Akt pathway and the upregulation of the PLC-IP3 pathway are well explained. The model explains why neurons are less protected from inflammation and why microglia are activated; why mitochondria are destabilized; why the autophagic flux is destabilized; and why the post-transcriptional attenuation of the axonal signal “noise” is interrupted. For example, the model suggests that Aβ peptide may post-transcriptionally control ELAVL2 (ELAV-like RNA binding protein 2) and DCP2 (decapping mRNA protein 2), which are known to regulate RNA processing, transport, and stability.
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