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Chustecki JM, Johnston IG. Collective mitochondrial dynamics resolve conflicting cellular tensions: From plants to general principles. Semin Cell Dev Biol 2024; 156:253-265. [PMID: 38043948 DOI: 10.1016/j.semcdb.2023.09.005] [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: 06/05/2023] [Revised: 08/18/2023] [Accepted: 09/15/2023] [Indexed: 12/05/2023]
Abstract
Mitochondria play diverse and essential roles in eukaryotic cells, and plants are no exception. Plant mitochondria have several differences from their metazoan and fungal cousins: they often exist in a fragmented state, move rapidly on actin rather than microtubules, have many plant-specific metabolic features and roles, and usually contain only a subset of the complete mtDNA genome, which itself undergoes frequent recombination. This arrangement means that exchange and complementation is essential for plant mitochondria, and recent work has begun to reveal how their collective dynamics and resultant "social networks" of encounters support this exchange, connecting plant mitochondria in time rather than in space. This review will argue that this social network perspective can be extended to a "societal network", where mitochondrial dynamics are an essential part of the interacting cellular society of organelles and biomolecules. Evidence is emerging that mitochondrial dynamics allow optimal resolutions to competing cellular priorities; we will survey this evidence and review potential future research directions, highlighting that plant mitochondria can help reveal and test principles that apply across other kingdoms of life. In parallel with this fundamental cell biology, we also highlight the translational "One Health" importance of plant mitochondrial behaviour - which is exploited in the production of a vast amount of crops consumed worldwide - and the potential for multi-objective optimisation to understand and rationally re-engineer the evolved resolutions to these tensions.
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Affiliation(s)
- Joanna M Chustecki
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Iain G Johnston
- Department of Mathematics, University of Bergen, Bergen, Norway; Computational Biology Unit, University of Bergen, Bergen, Norway.
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Broatch JR, Zarekookandeh N, Glarin R, Strik M, Johnston LA, Moffat BA, Bird LJ, Gunningham K, Churilov L, Johns HT, Askew CD, Levinger I, O'Riordan SF, Bishop DJ, Brodtmann A. Train Smart Study: protocol for a randomised trial investigating the role of exercise training dose on markers of brain health in sedentary middle-aged adults. BMJ Open 2023; 13:e069413. [PMID: 37225276 DOI: 10.1136/bmjopen-2022-069413] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
INTRODUCTION Regular aerobic exercise is associated with improved cognitive function, implicating it as a strategy to reduce dementia risk. This is reinforced by the association between greater cardiorespiratory fitness and larger brain volume, superior cognitive performance and lower dementia risk. However, the optimal aerobic exercise dose, namely the intensity and mode of delivery, to improve brain health and lower dementia risk has received less attention. We aim to determine the effect of different doses of aerobic exercise training on markers of brain health in sedentary middle-aged adults, hypothesising that high-intensity interval training (HIIT) will be more beneficial than moderate-intensity continuous training (MICT). METHODS AND ANALYSIS In this two-group parallel, open-label blinded endpoint randomised trial, 70 sedentary middle-aged (45-65 years) adults will be randomly allocated to one of two 12-week aerobic exercise training interventions matched for total exercise training volume: (1) MICT (n=35) or HIIT (n=35). Participants will perform ~50 min exercise training sessions, 3 days per week, for 12 weeks. The primary outcome will be measured as between-group difference in cardiorespiratory fitness (peak oxygen uptake) change from baseline to the end of training. Secondary outcomes include between-group differences in cognitive function and ultra-high field MRI (7T) measured markers of brain health (brain blood flow, cerebrovascular function, brain volume, white matter microstructural integrity and resting state functional brain activity) changes from baseline to the end of training. ETHICS AND DISSEMINATION The Victoria University Human Research Ethics Committee (VUHREC) has approved this study (HRE20178), and all protocol modifications will be communicated to the relevant parties (eg, VUHREC, trial registry). Findings from this study will be disseminated via peer-review publications, conference presentations, clinical communications and both mainstream and social media. TRIAL REGISTRATION NUMBER ANZCTR12621000144819.
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Affiliation(s)
- James R Broatch
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
| | - Navabeh Zarekookandeh
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
| | - Rebecca Glarin
- Melbourne Brain Centre Imaging Unit, Department of Radiology, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Radiology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Myrte Strik
- Melbourne Brain Centre Imaging Unit, Department of Radiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Leigh A Johnston
- Melbourne Brain Centre Imaging Unit, Department of Radiology, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
| | - Bradford A Moffat
- Melbourne Brain Centre Imaging Unit, Department of Radiology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Laura J Bird
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia
| | - Kate Gunningham
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
| | - Leonid Churilov
- Melbourne Medical School, The University of Melbourne, Melbourne, Victoria, Australia
| | - Hannah T Johns
- Melbourne Medical School, The University of Melbourne, Melbourne, Victoria, Australia
- Australian Stroke Alliance, Melbourne Brain Centre, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Christopher D Askew
- Sunshine Coast Health Institute, Sunshine Coast Hospital and Health Service, Nambour, Queensland, Australia
- School of Health, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Itamar Levinger
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
- The Australian Institute of Musculoskeletal Sciences, Melbourne, Victoria, Australia
| | - Shane F O'Riordan
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
| | - David J Bishop
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Victoria, Australia
| | - Amy Brodtmann
- Cognitive Health Initiative, Central Clinical School, Monash University, Clayton, Victoria, Australia
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia
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Williams CF, Hather C, Conteh JS, Zhang J, Popa RG, Owen AW, Jonas CL, Choi H, Daniel RM, Lloyd D, Porch A, George CH. Non-thermal disruption of β-adrenergic receptor-activated Ca 2+ signalling and apoptosis in human ES-derived cardiomyocytes by microwave electric fields at 2.4 GHz. Biochem Biophys Res Commun 2023; 661:89-98. [PMID: 37087803 DOI: 10.1016/j.bbrc.2023.04.038] [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: 03/30/2023] [Accepted: 04/15/2023] [Indexed: 04/25/2023]
Abstract
The ubiquity of wireless electronic-device connectivity has seen microwaves emerge as one of the fastest growing forms of electromagnetic exposure. A growing evidence-base refutes the claim that wireless technologies pose no risk to human health at current safety levels designed to limit thermal (heating) effects. The potential impact of non-thermal effects of microwave exposure, especially in electrically-excitable tissues (e.g., heart), remains controversial. We exposed human embryonic stem-cell derived cardiomyocytes (CM), under baseline and beta-adrenergic receptor (β-AR)-stimulated conditions, to microwaves at 2.4 GHz, a frequency used extensively in wireless communication (e.g., 4G, Bluetooth™ and WiFi). To control for any effect of sample heating, experiments were done in CM subjected to matched rates of direct heating or CM maintained at 37 °C. Detailed profiling of the temporal and amplitude features of Ca2+ signalling in CM under these experimental conditions was reconciled with the extent and spatial clustering of apoptosis. The data show that exposure of CM to 2.4 GHz EMF eliminated the normal Ca2+ signalling response to β-AR stimulation and provoked spatially-clustered apoptosis. This is first evidence that non-thermal effects of 2.4 GHz microwaves might have profound effects on human CM function, responsiveness to activation, and survival.
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Affiliation(s)
- Catrin F Williams
- School of Engineering, Cardiff University, Wales, UK; School of Biosciences, Cardiff University, Wales, UK
| | | | | | | | | | | | | | - Heungjae Choi
- School of Engineering, Cardiff University, Wales, UK
| | | | - David Lloyd
- School of Engineering, Cardiff University, Wales, UK; School of Biosciences, Cardiff University, Wales, UK
| | - Adrian Porch
- School of Engineering, Cardiff University, Wales, UK.
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Giannakis K, Chustecki JM, Johnston IG. Exchange on dynamic encounter networks allows plant mitochondria to collect complete sets of mitochondrial DNA products despite their incomplete genomes. QUANTITATIVE PLANT BIOLOGY 2022; 3:e18. [PMID: 37077986 PMCID: PMC10095876 DOI: 10.1017/qpb.2022.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 07/26/2022] [Accepted: 07/26/2022] [Indexed: 05/03/2023]
Abstract
Mitochondria in plant cells usually contain less than a full copy of the mitochondrial DNA (mtDNA) genome. Here, we asked whether mitochondrial dynamics may allow individual mitochondria to 'collect' a full set of mtDNA-encoded gene products over time, by facilitating exchange between individuals akin to trade on a social network. We characterise the collective dynamics of mitochondria in Arabidopsis hypocotyl cells using a recent approach combining single-cell time-lapse microscopy, video analysis and network science. We use a quantitative model to predict the capacity for sharing genetic information and gene products through the networks of encounters between mitochondria. We find that biological encounter networks support the emergence of gene product sets over time more readily than a range of other possible network structures. Using results from combinatorics, we identify the network statistics that determine this propensity, and discuss how features of mitochondrial dynamics observed in biology facilitate the collection of mtDNA-encoded gene products.
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Affiliation(s)
| | | | - Iain G. Johnston
- Department of Mathematics, University of Bergen, Bergen, Norway
- Computational Biology Unit, University of Bergen, Bergen, Norway
- Author for correspondence: I. G. Johnston, E-mail:
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Abstract
Mitochondria are organelles with vital functions in almost all eukaryotic cells. Often described as the cellular 'powerhouses' due to their essential role in aerobic oxidative phosphorylation, mitochondria perform many other essential functions beyond energy production. As signaling organelles, mitochondria communicate with the nucleus and other organelles to help maintain cellular homeostasis, allow cellular adaptation to diverse stresses, and help steer cell fate decisions during development. Mitochondria have taken center stage in the research of normal and pathological processes, including normal tissue homeostasis and metabolism, neurodegeneration, immunity and infectious diseases. The central role that mitochondria assume within cells is evidenced by the broad impact of mitochondrial diseases, caused by defects in either mitochondrial or nuclear genes encoding for mitochondrial proteins, on different organ systems. In this Review, we will provide the reader with a foundation of the mitochondrial 'hardware', the mitochondrion itself, with its specific dynamics, quality control mechanisms and cross-organelle communication, including its roles as a driver of an innate immune response, all with a focus on development, disease and aging. We will further discuss how mitochondrial DNA is inherited, how its mutation affects cell and organismal fitness, and current therapeutic approaches for mitochondrial diseases in both model organisms and humans.
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Affiliation(s)
- Marlies P. Rossmann
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 01238, USA
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Sonia M. Dubois
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Suneet Agarwal
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Leonard I. Zon
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 01238, USA
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Howard Hughes Medical Institute, Boston, MA 02115, USA
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Chustecki JM, Gibbs DJ, Bassel GW, Johnston IG. Network analysis of Arabidopsis mitochondrial dynamics reveals a resolved tradeoff between physical distribution and social connectivity. Cell Syst 2021; 12:419-431.e4. [PMID: 34015261 PMCID: PMC8136767 DOI: 10.1016/j.cels.2021.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/22/2021] [Accepted: 04/13/2021] [Indexed: 11/27/2022]
Abstract
Mitochondria in plant cells exist largely as individual organelles which move, colocalize, and interact, but the cellular priorities addressed by these dynamics remain incompletely understood. Here, we elucidate these principles by studying the dynamic "social networks" of mitochondria in Arabidopsis thaliana wildtype and mutants, describing the colocalization of individuals over time. We combine single-cell live imaging of hypocotyl mitochondrial dynamics with individual-based modeling and network analysis. We identify an inevitable tradeoff between mitochondrial physical priorities (an even cellular distribution of mitochondria) and “social” priorities (individuals interacting, to facilitate the exchange of chemicals and information). This tradeoff results in a tension between maintaining mitochondrial spacing and facilitating colocalization. We find that plant cells resolve this tension to favor efficient networks with high potential for exchanging contents. We suggest that this combination of physical modeling coupled to experimental data through network analysis can shed light on the fundamental principles underlying these complex organelle dynamics. A record of this paper’s transparent peer review process is included in the supplemental information. Dynamic social networks of plant mitochondria reflect physical organellar encounters Network analysis and modeling show priorities and tradeoffs for mitochondrial motion Mitochondria in plant cells trade off physical spacing against social connectivity Plant cells favor efficient networks with high potential for information exchange
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Affiliation(s)
| | - Daniel J Gibbs
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - George W Bassel
- Department of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Iain G Johnston
- Department of Mathematics, University of Bergen, Realfagbygget, Bergen 5007, Norway; Computational Biology Unit, University of Bergen, Høyteknologisenteret i Bergen, Bergen 5008, Norway.
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