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Campbell D, Zuryn S. The mechanisms and roles of mitochondrial dynamics in C. elegans. Semin Cell Dev Biol 2024; 156:266-275. [PMID: 37919144 DOI: 10.1016/j.semcdb.2023.10.006] [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: 06/18/2023] [Revised: 10/15/2023] [Accepted: 10/26/2023] [Indexed: 11/04/2023]
Abstract
If mitochondria are the powerhouses of the cell, then mitochondrial dynamics are the power grid that regulates how that energy output is directed and maintained in response to unique physiological demands. Fission and fusion dynamics are highly regulated processes that fine-tune the mitochondrial networks of cells to enable appropriate responses to intrinsic and extrinsic stimuli, thereby maintaining cellular and organismal homeostasis. These dynamics shape many aspects of an organism's healthspan including development, longevity, stress resistance, immunity, and response to disease. In this review, we discuss the latest findings regarding the mechanisms and roles of mitochondrial dynamics by focussing on the nematode Caenorhabditis elegans. Whole live-animal studies in C. elegans have enabled a true organismal-level understanding of the impact that mitochondrial dynamics play in homeostasis over a lifetime.
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Affiliation(s)
- Daniel Campbell
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Steven Zuryn
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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Michaeli L, Spector E, Haeussler S, Carvalho CA, Grobe H, Abu-Shach UB, Zinger H, Conradt B, Broday L. ULP-2 SUMO protease regulates UPR mt and mitochondrial homeostasis in Caenorhabditis elegans. Free Radic Biol Med 2024; 214:19-27. [PMID: 38301974 PMCID: PMC10929073 DOI: 10.1016/j.freeradbiomed.2024.01.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/19/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
Mitochondria are the powerhouses of cells, responsible for energy production and regulation of cellular homeostasis. When mitochondrial function is impaired, a stress response termed mitochondrial unfolded protein response (UPRmt) is initiated to restore mitochondrial function. Since mitochondria and UPRmt are implicated in many diseases, it is important to understand UPRmt regulation. In this study, we show that the SUMO protease ULP-2 has a key role in regulating mitochondrial function and UPRmt. Specifically, down-regulation of ulp-2 suppresses UPRmt and reduces mitochondrial membrane potential without significantly affecting cellular ROS. Mitochondrial networks are expanded in ulp-2 null mutants with larger mitochondrial area and increased branching. Moreover, the amount of mitochondrial DNA is increased in ulp-2 mutants. Downregulation of ULP-2 also leads to alterations in expression levels of mitochondrial genes involved in protein import and mtDNA replication, however, mitophagy remains unaltered. In summary, this study demonstrates that ULP-2 is required for mitochondrial homeostasis and the UPRmt.
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Affiliation(s)
- Lirin Michaeli
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Eyal Spector
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Simon Haeussler
- Faculty of Biology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Cátia A Carvalho
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Hanna Grobe
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ulrike Bening Abu-Shach
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Hen Zinger
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Barbara Conradt
- Faculty of Biology, Ludwig-Maximilians-University Munich, Munich, Germany; Department of Cell and Developmental Biology, Division of Biosciences, University College London, London, United Kingdom
| | - Limor Broday
- Department of Cell and Developmental Biology, School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
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Dodge JD, Browder NJ, Pellegrino MW. Mitochondrial recovery by the UPR mt: Insights from C. elegans. Semin Cell Dev Biol 2024; 154:59-68. [PMID: 36792440 DOI: 10.1016/j.semcdb.2023.02.002] [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: 01/14/2023] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/15/2023]
Abstract
Mitochondria are multifaceted organelles, with such functions as the production of cellular energy to the regulation of cell death. However, mitochondria incur various sources of damage from the accumulation of reactive oxygen species and DNA mutations that can impact the protein folding environment and impair their function. Since mitochondrial dysfunction is often associated with reductions in organismal fitness and possibly disease, cells must have safeguards in place to protect mitochondrial function and promote recovery during times of stress. The mitochondrial unfolded protein response (UPRmt) is a transcriptional adaptation that promotes mitochondrial repair to aid in cell survival during stress. While the earlier discoveries into the regulation of the UPRmt stemmed from studies using mammalian cell culture, much of our understanding about this stress response has been bestowed to us by the model organism Caenorhabditis elegans. Indeed, the facile but powerful genetics of this relatively simple nematode has uncovered multiple regulators of the UPRmt, as well as several physiological roles of this stress response. In this review, we will summarize these major advancements originating from studies using C. elegans.
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Affiliation(s)
- Joshua D Dodge
- The University of Texas at Arlington, Department of Biology, Arlington, TX 76019, USA
| | - Nicholas J Browder
- The University of Texas at Arlington, Department of Biology, Arlington, TX 76019, USA
| | - Mark W Pellegrino
- The University of Texas at Arlington, Department of Biology, Arlington, TX 76019, USA.
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Kumar M, Sharma S, Mazumder S. Role of UPR mt and mitochondrial dynamics in host immunity: it takes two to tango. Front Cell Infect Microbiol 2023; 13:1135203. [PMID: 37260703 PMCID: PMC10227438 DOI: 10.3389/fcimb.2023.1135203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 04/24/2023] [Indexed: 06/02/2023] Open
Abstract
The immune system of a host contains a group of heterogeneous cells with the prime aim of restraining pathogenic infection and maintaining homeostasis. Recent reports have proved that the various subtypes of immune cells exploit distinct metabolic programs for their functioning. Mitochondria are central signaling organelles regulating a range of cellular activities including metabolic reprogramming and immune homeostasis which eventually decree the immunological fate of the host under pathogenic stress. Emerging evidence suggests that following bacterial infection, innate immune cells undergo profound metabolic switching to restrain and countervail the bacterial pathogens, promote inflammation and restore tissue homeostasis. On the other hand, bacterial pathogens affect mitochondrial structure and functions to evade host immunity and influence their intracellular survival. Mitochondria employ several mechanisms to overcome bacterial stress of which mitochondrial UPR (UPRmt) and mitochondrial dynamics are critical. This review discusses the latest advances in our understanding of the immune functions of mitochondria against bacterial infection, particularly the mechanisms of mitochondrial UPRmt and mitochondrial dynamics and their involvement in host immunity.
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Affiliation(s)
- Manmohan Kumar
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
| | - Shagun Sharma
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
| | - Shibnath Mazumder
- Immunobiology Laboratory, Department of Zoology, University of Delhi, Delhi, India
- Faculty of Life Sciences and Biotechnology, South Asian University, Delhi, India
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Rolland S, Conradt B. Genetic screen identifies non-mitochondrial proteins involved in the maintenance of mitochondrial homeostasis. MICROPUBLICATION BIOLOGY 2022; 2022:10.17912/micropub.biology.000562. [PMID: 35622507 PMCID: PMC9099400 DOI: 10.17912/micropub.biology.000562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 04/28/2022] [Accepted: 05/02/2022] [Indexed: 11/06/2022]
Abstract
The mitochondrial unfolded protein response (UPR mt ) is an important stress response that ensures the maintenance of mitochondrial homeostasis in response to various types of cellular stress. We previously described a genetic screen for Caenorhabditis elegans genes, which when inactivated cause UPR mt activation, and reported genes identified that encode mitochondrial proteins. We now report additional genes identified in the screen. Importantly, these include genes that encode non-mitochondrial proteins involved in processes such as the control of gene expression, post-translational modifications, cell signaling and cellular trafficking. Interestingly, we identified several genes that have been proposed to participate in the transfer of lipids between peroxisomes, ER and mitochondria, suggesting that lipid transfer between these organelles is essential for mitochondrial homeostasis. In conclusion, this study shows that the maintenance of mitochondrial homeostasis is not only dependent on mitochondrial processes but also relies on non-mitochondrial processes and pathways. Our results reinforce the notion that mitochondrial function and cellular function are intimately connected.
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Affiliation(s)
- Stephane Rolland
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
- Current Address: Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan 44919, South Korea
| | - Barbara Conradt
- Faculty of Biology, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
- Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
- Current Address: Department of Cell and Developmental Biology, Division of Biosciences, University College London, London WC1E 6AP, United Kingdom
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