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Li Z, Liang S, Ke L, Wang M, Gao K, Li D, Xu Z, Li N, Zhang P, Cheng W. Cell life-or-death events in osteoporosis: All roads lead to mitochondrial dynamics. Pharmacol Res 2024; 208:107383. [PMID: 39214266 DOI: 10.1016/j.phrs.2024.107383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Revised: 08/14/2024] [Accepted: 08/26/2024] [Indexed: 09/04/2024]
Abstract
Mitochondria exhibit heterogeneous shapes and networks within and among cell types and tissues, also in normal or osteoporotic bone tissues with complex cell types. This dynamic characteristic is determined by the high plasticity provided by mitochondrial dynamics and is stemmed from responding to the survival and functional requirements of various bone cells in a specific microenvironments. In contrast, mitochondrial dysfunction, induced by dysregulation of mitochondrial dynamics, may act as a trigger of cell death signals, including common apoptosis and other forms of programmed cell death (PCD). These PCD processes consisting of tightly structured cascade gene expression events, can further influence the bone remodeling by facilitating the death of various bone cells. Mitochondrial dynamics, therefore, drive the bone cells to stand at the crossroads of life and death by integrating external signals and altering metabolism, shape, and signal-response properties of mitochondria. This implies that targeting mitochondrial dynamics displays significant potential in treatment of osteoporosis. Considerable effort has been made in osteoporosis to emphasize the parallel roles of mitochondria in regulating energy metabolism, calcium signal transduction, oxidative stress, inflammation, and cell death. However, the emerging field of mitochondrial dynamics-related PCD is not well understood. Herein, to bridge the gap, we outline the latest knowledge on mitochondrial dynamics regulating bone cell life or death during normal bone remodeling and osteoporosis.
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Affiliation(s)
- Zhichao Li
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China; Center for Translational Medicine Research and Development, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China; Department of Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250014, China
| | - Songlin Liang
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China; Center for Translational Medicine Research and Development, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Liqing Ke
- Center for Translational Medicine Research and Development, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Mengjie Wang
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China
| | - Kuanhui Gao
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China
| | - Dandan Li
- College of Integrated Traditional Chinese and Western Medicine, Hebei University of Chinese Medicine, Shijiazhuang, 050011, China
| | - Zhanwang Xu
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China; Department of Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250014, China
| | - Nianhu Li
- First College of Clinical Medicine, Shandong University of Traditional Chinese Medicine, Jinan, 250014, China; Department of Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250014, China.
| | - Peng Zhang
- Center for Translational Medicine Research and Development, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China; Faculty of Biomedical Engineering, Shenzhen University of Advanced Technology, Shenzhen, 518000, China; Key Laboratory of Biomedical Imaging Science and System, Chinese Academy of Sciences, Shenzhen, 518000, China; Shandong Zhongke Advanced Technology Co., Ltd., Jinan, 250300, China.
| | - Wenxiang Cheng
- Center for Translational Medicine Research and Development, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
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2
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Parry HA, Willingham TB, Giordano KA, Kim Y, Qazi S, Knutson JR, Combs CA, Glancy B. Impact of capillary and sarcolemmal proximity on mitochondrial structure and energetic function in skeletal muscle. J Physiol 2024; 602:1967-1986. [PMID: 38564214 PMCID: PMC11068488 DOI: 10.1113/jp286246] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024] Open
Abstract
Mitochondria within skeletal muscle cells are located either between the muscle contractile apparatus (interfibrillar mitochondria, IFM) or beneath the cell membrane (subsarcolemmal mitochondria, SSM), with several structural and functional differences reported between IFM and SSM. However, recent 3D imaging studies demonstrate that mitochondria are particularly concentrated in the proximity of capillaries embedded in sarcolemmal grooves rather than in proximity to the sarcolemma itself (paravascular mitochondria, PVM). To evaluate the impact of capillary vs. sarcolemmal proximity, we compared the structure and function of skeletal muscle mitochondria located either lateral to embedded capillaries (PVM), adjacent to the sarcolemma but not in PVM pools (SSM) or interspersed between sarcomeres (IFM). Mitochondrial morphology and interactions were assessed by 3D electron microscopy coupled with machine learning segmentation, whereas mitochondrial energy conversion was assessed by two-photon microscopy of mitochondrial membrane potential, content, calcium, NADH redox and flux in live, intact cells. Structurally, although PVM and SSM were similarly larger than IFM, PVM were larger, rounder and had more physical connections to neighbouring mitochondria compared to both IFM and SSM. Functionally, PVM had similar or greater basal NADH flux compared to SSM and IFM, respectively, despite a more oxidized NADH pool and a greater membrane potential, signifying a greater activation of the electron transport chain in PVM. Together, these data indicate that proximity to capillaries has a greater impact on resting mitochondrial energy conversion and distribution in skeletal muscle than the sarcolemma alone. KEY POINTS: Capillaries have a greater impact on mitochondrial energy conversion in skeletal muscle than the sarcolemma. Paravascular mitochondria are larger, and the outer mitochondrial membrane is more connected with neighbouring mitochondria. Interfibrillar mitochondria are longer and have greater contact sites with other organelles (i.e. sarcoplasmic reticulum and lipid droplets). Paravascular mitochondria have greater activation of oxidative phosphorylation than interfibrillar mitochondria at rest, although this is not regulated by calcium.
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Affiliation(s)
- Hailey A. Parry
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - T. Bradley Willingham
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- Shephard Center’s Virginia C. Crawford Research Institute, Atlanta, GA, USA
| | | | - Yuho Kim
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- University of Massachusetts, Lowell, MA,USA
| | - Shureed Qazi
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jay R. Knutson
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Christian A. Combs
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
| | - Brian Glancy
- National Lung, Blood, and Heart Institute, National Institutes of Health, Bethesda, MD, USA
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
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3
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Jenkins BC, Neikirk K, Katti P, Claypool SM, Kirabo A, McReynolds MR, Hinton A. Mitochondria in disease: changes in shapes and dynamics. Trends Biochem Sci 2024; 49:346-360. [PMID: 38402097 PMCID: PMC10997448 DOI: 10.1016/j.tibs.2024.01.011] [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: 09/05/2023] [Revised: 01/14/2024] [Accepted: 01/26/2024] [Indexed: 02/26/2024]
Abstract
Mitochondrial structure often determines the function of these highly dynamic, multifunctional, eukaryotic organelles, which are essential for maintaining cellular health. The dynamic nature of mitochondria is apparent in descriptions of different mitochondrial shapes [e.g., donuts, megamitochondria (MGs), and nanotunnels] and crista dynamics. This review explores the significance of dynamic alterations in mitochondrial morphology and regulators of mitochondrial and cristae shape. We focus on studies across tissue types and also describe new microscopy techniques for detecting mitochondrial morphologies both in vivo and in vitro that can improve understanding of mitochondrial structure. We highlight the potential therapeutic benefits of regulating mitochondrial morphology and discuss prospective avenues to restore mitochondrial bioenergetics to manage diseases related to mitochondrial dysfunction.
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Affiliation(s)
- Brenita C Jenkins
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801, USA
| | - Kit Neikirk
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna Katti
- National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Steven M Claypool
- Department of Physiology, Mitochondrial Phospholipid Research Center, Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Annet Kirabo
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Center for Immunobiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Infection, Immunology and Inflammation, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Vanderbilt Institute for Global Health, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Melanie R McReynolds
- Department of Biochemistry and Molecular Biology, The Huck Institute of the Life Sciences, Pennsylvania State University, State College, PA 16801, USA.
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Kim Y, Parry HA, Willingham TB, Alspaugh G, Lindberg E, Combs CA, Knutson JR, Bleck CKE, Glancy B. Reorganization of mitochondria-organelle interactions during postnatal development in skeletal muscle. J Physiol 2024; 602:891-912. [PMID: 38429930 PMCID: PMC10939894 DOI: 10.1113/jp285014] [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: 05/12/2023] [Accepted: 01/16/2024] [Indexed: 03/03/2024] Open
Abstract
Skeletal muscle cellular development requires the integrated assembly of mitochondria and other organelles adjacent to the sarcomere in support of muscle contractile performance. However, it remains unclear how interactions among organelles and with the sarcomere relates to the development of muscle cell function. Here, we combine 3D volume electron microscopy, proteomic analyses, and live cell functional imaging to investigate the postnatal reorganization of mitochondria-organelle interactions in skeletal muscle. We show that while mitochondrial networks are disorganized and loosely associated with the contractile apparatus at birth, contact sites among mitochondria, lipid droplets and the sarcoplasmic reticulum are highly abundant in neonatal muscles. The maturation process is characterized by a transition to highly organized mitochondrial networks wrapped tightly around the muscle sarcomere but also to less frequent interactions with both lipid droplets and the sarcoplasmic reticulum. Concomitantly, expression of proteins involved in mitochondria-organelle membrane contact sites decreases during postnatal development in tandem with a decrease in abundance of proteins associated with sarcomere assembly despite an overall increase in contractile protein abundance. Functionally, parallel measures of mitochondrial membrane potential, NADH redox status, and NADH flux within intact cells revealed that mitochondria in adult skeletal muscle fibres maintain a more activated electron transport chain compared with neonatal muscle mitochondria. These data demonstrate a developmental redesign reflecting a shift from muscle cell assembly and frequent inter-organelle communication toward a muscle fibre with mitochondrial structure, interactions, composition and function specialized to support contractile function. KEY POINTS: Mitochondrial network organization is remodelled during skeletal muscle postnatal development. The mitochondrial outer membrane is in frequent contact with other organelles at birth and transitions to more close associations with the contractile apparatus in mature muscles. Mitochondrial energy metabolism becomes more activated during postnatal development. Understanding the developmental redesign process within skeletal muscle cells may help pinpoint specific areas of deficit in muscles with developmental disorders.
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Affiliation(s)
- Yuho Kim
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, MA 01854, USA
| | - Hailey A. Parry
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - T. Bradley Willingham
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Greg Alspaugh
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Eric Lindberg
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Christian A. Combs
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Jay R. Knutson
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Christopher K. E. Bleck
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
| | - Brian Glancy
- National Heart, Lung, and Blood Institute National Institutes of Health, Bethesda, MD 20892, USA
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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5
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Roman B, Mastoor Y, Zhang Y, Gross D, Springer D, Liu C, Glancy B, Murphy E. Loss of mitochondrial Ca 2+ uptake protein 3 impairs skeletal muscle calcium handling and exercise capacity. J Physiol 2024; 602:113-128. [PMID: 38018177 PMCID: PMC10824360 DOI: 10.1113/jp284894] [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: 04/14/2023] [Accepted: 11/06/2023] [Indexed: 11/30/2023] Open
Abstract
Mitochondrial calcium concentration ([Ca2+ ]m ) plays an essential role in bioenergetics, and loss of [Ca2+ ]m homeostasis can trigger diseases and cell death in numerous cell types. Ca2+ uptake into mitochondria occurs via the mitochondrial Ca2+ uniporter (MCU), which is regulated by three mitochondrial Ca2+ uptake (MICU) proteins localized in the intermembrane space, MICU1, 2, and 3. We generated a mouse model of systemic MICU3 ablation and examined its physiological role in skeletal muscle. We found that loss of MICU3 led to impaired exercise capacity. When the muscles were directly stimulated there was a decrease in time to fatigue. MICU3 ablation significantly increased the maximal force of the KO muscle and altered fibre type composition with an increase in the ratio of type IIb (low oxidative capacity) to type IIa (high oxidative capacity) fibres. Furthermore, MICU3-KO mitochondria have reduced uptake of Ca2+ and increased phosphorylation of pyruvate dehydrogenase, indicating that KO animals contain less Ca2+ in their mitochondria. Skeletal muscle from MICU3-KO mice exhibited lower net oxidation of NADH during electrically stimulated muscle contraction compared with wild-type. These data demonstrate that MICU3 plays a role in skeletal muscle physiology by setting the proper threshold for mitochondrial Ca2+ uptake, which is important for matching energy demand and supply in muscle. KEY POINTS: Mitochondrial calcium uptake is an important regulator of bioenergetics and cell death and is regulated by the mitochondrial calcium uniporter (MCU) and three calcium sensitive regulatory proteins (MICU1, 2 and 3). Loss of MICU3 leads to impaired exercise capacity and decreased time to skeletal muscle fatigue. Skeletal muscle from MICU3-KO mice exhibits a net oxidation of NADH during electrically stimulated muscle contractions, suggesting that MICU3 plays a role in skeletal muscle physiology by matching energy demand and supply.
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Affiliation(s)
| | | | - Yingfan Zhang
- Muscle Energetics, NHLBI, and NIAMS, NIH, Bethesda, MD, USA
| | - Dennis Gross
- Cardiac Physiology, NHLBI, NIH, Bethesda, MD, USA
| | | | - Chengyu Liu
- Transgenic Core, NHLBI, NIH, Bethesda, MD, USA
| | - Brian Glancy
- Muscle Energetics, NHLBI, and NIAMS, NIH, Bethesda, MD, USA
- Transgenic Core, NHLBI, NIH, Bethesda, MD, USA
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6
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Energy transfer between the mitochondrial network and lipid droplets in insulin resistant skeletal muscle. CURRENT OPINION IN PHYSIOLOGY 2021; 24:100487. [PMID: 35274067 PMCID: PMC8903156 DOI: 10.1016/j.cophys.2022.100487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondria and lipid droplets in the insulin resistant skeletal muscle of type 2 diabetic individuals have both been heavily investigated independently and are characterized by more fragmented, dysfunctional mitochondrial networks and larger lipid droplets compared to skeletal muscle of healthy individuals. Specialized contacts between mitochondrial and lipid droplet membranes are known to decrease in diabetic muscle, though it remains unclear how energy transfer at the remaining mitochondria-lipid droplet contact sites may be altered by type 2 diabetes. The purpose of this review is to highlight recent data on mitochondrial structure and function and lipid droplet dynamics in type 2 diabetic skeletal muscle and to underscore the need for more detailed investigations into the functional nature of mitochondria-lipid droplet interactions in type 2 diabetes.
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Willingham TB, Ajayi PT, Glancy B. Subcellular Specialization of Mitochondrial Form and Function in Skeletal Muscle Cells. Front Cell Dev Biol 2021; 9:757305. [PMID: 34722542 PMCID: PMC8554132 DOI: 10.3389/fcell.2021.757305] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/27/2021] [Indexed: 11/22/2022] Open
Abstract
Across different cell types and within single cells, mitochondria are heterogeneous in form and function. In skeletal muscle cells, morphologically and functionally distinct subpopulations of mitochondria have been identified, but the mechanisms by which the subcellular specialization of mitochondria contributes to energy homeostasis in working muscles remains unclear. Here, we discuss the current data regarding mitochondrial heterogeneity in skeletal muscle cells and highlight potential new lines of inquiry that have emerged due to advancements in cellular imaging technologies.
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Affiliation(s)
- T. Bradley Willingham
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Peter T. Ajayi
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Brian Glancy
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
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8
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An energetics perspective on geroscience: mitochondrial protonmotive force and aging. GeroScience 2021; 43:1591-1604. [PMID: 33864592 DOI: 10.1007/s11357-021-00365-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/07/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondria are organelles that provide energy to cells through ATP production. Mitochondrial dysfunction has long been postulated to mediate cellular declines that drive biological aging. Many well-characterized hallmarks of aging may involve underlying energetic defects that stem from loss of mitochondrial function with age. Why and how mitochondrial function declines with age is an open question and one that has been difficult to answer. Mitochondria are powered by an electrochemical gradient across the inner mitochondrial membrane known as the protonmotive force (PMF). This gradient decreases with age in several experimental models. However, it is unclear if a diminished PMF is a cause or a consequence of aging. Herein, we briefly review and define mitochondrial function, we summarize how PMF changes with age in several models, and we highlight recent studies that implicate PMF in aging biology. We also identify barriers that must be addressed for the field to progress. Emerging technology permits more precise in vivo study of mitochondria that will allow better understanding of cause and effect in metabolic models of aging. Once cause and effect can be discerned more precisely, energetics approaches to combat aging may be developed to prevent or reverse functional decline.
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9
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10
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Qualls AE, Southern WM, Call JA. Mitochondria-cytokine crosstalk following skeletal muscle injury and disuse: a mini-review. Am J Physiol Cell Physiol 2021; 320:C681-C688. [PMID: 33566726 DOI: 10.1152/ajpcell.00462.2020] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Skeletal muscle mitochondria are highly adaptable, highly dynamic organelles that maintain the functional integrity of the muscle fiber by providing ATP for contraction and cellular homeostasis (e.g., Na+/K+ ATPase). Emerging as early modulators of inflammation, mitochondria sense and respond to cellular stress. Mitochondria communicate with the environment, in part, by release of physical signals called mitochondrial-derived damage-associated molecular patterns (mito-DAMPs) and deviation from routine function (e.g., reduced ATP production, Ca2+ overload). When skeletal muscle is compromised, mitochondria contribute to an acute inflammatory response necessary for myofibril regeneration; however, exhaustive signaling associated with altered or reduced mitochondrial function can be detrimental to muscle outcomes. Here, we describe changes in mitochondrial content, structure, and function following skeletal muscle injury and disuse and highlight the influence of mitochondria-cytokine crosstalk on muscle regeneration and recovery. Although the appropriate therapeutic modulation following muscle stressors remains unknown, retrospective gene expression analysis reveals that interleukin-6 (IL-6), interleukin-1β (IL-1β), chemokine C-X-C motif ligand 1 (CXCL1), and monocyte chemoattractant protein 1 (MCP-1) are significantly upregulated following three unique muscle injuries. These cytokines modulate mitochondrial function and execute bona fide pleiotropic roles that can aid functional recovery of muscle, however, when aberrant, chronically disrupt healing partly by exacerbating mitochondrial dysfunction. Multidisciplinary efforts to delineate the opposing regulatory roles of inflammatory cytokines in the muscle mitochondrial environment are required to modulate regenerative behavior following skeletal muscle injury or disuse. Future therapeutic directions to consider include quenching or limited release of mito-DAMPs and cytokines present in cytosol or circulation.
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Affiliation(s)
- Anita E Qualls
- Clinical School, University of Cambridge, Cambridge, United Kingdom
| | - W Michael Southern
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Jarrod A Call
- Department of Kinesiology, University of Georgia, Athens, Georgia.,Regenerative Bioscience Center, University of Georgia, Athens, Georgia
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11
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Glancy B, Kim Y, Katti P, Willingham TB. The Functional Impact of Mitochondrial Structure Across Subcellular Scales. Front Physiol 2020; 11:541040. [PMID: 33262702 PMCID: PMC7686514 DOI: 10.3389/fphys.2020.541040] [Citation(s) in RCA: 122] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 10/20/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are key determinants of cellular health. However, the functional role of mitochondria varies from cell to cell depending on the relative demands for energy distribution, metabolite biosynthesis, and/or signaling. In order to support the specific needs of different cell types, mitochondrial functional capacity can be optimized in part by modulating mitochondrial structure across several different spatial scales. Here we discuss the functional implications of altering mitochondrial structure with an emphasis on the physiological trade-offs associated with different mitochondrial configurations. Within a mitochondrion, increasing the amount of cristae in the inner membrane improves capacity for energy conversion and free radical-mediated signaling but may come at the expense of matrix space where enzymes critical for metabolite biosynthesis and signaling reside. Electrically isolating individual cristae could provide a protective mechanism to limit the spread of dysfunction within a mitochondrion but may also slow the response time to an increase in cellular energy demand. For individual mitochondria, those with relatively greater surface areas can facilitate interactions with the cytosol or other organelles but may be more costly to remove through mitophagy due to the need for larger phagophore membranes. At the network scale, a large, stable mitochondrial reticulum can provide a structural pathway for energy distribution and communication across long distances yet also enable rapid spreading of localized dysfunction. Highly dynamic mitochondrial networks allow for frequent content mixing and communication but require constant cellular remodeling to accommodate the movement of mitochondria. The formation of contact sites between mitochondria and several other organelles provides a mechanism for specialized communication and direct content transfer between organelles. However, increasing the number of contact sites between mitochondria and any given organelle reduces the mitochondrial surface area available for contact sites with other organelles as well as for metabolite exchange with cytosol. Though the precise mechanisms guiding the coordinated multi-scale mitochondrial configurations observed in different cell types have yet to be elucidated, it is clear that mitochondrial structure is tailored at every level to optimize mitochondrial function to meet specific cellular demands.
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Affiliation(s)
- Brian Glancy
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
- NIAMS, National Institutes of Health, Bethesda, MD, United States
| | - Yuho Kim
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, Lowell, MA, United States
| | - Prasanna Katti
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
| | - T. Bradley Willingham
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
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12
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Berry BJ, Wojtovich AP. Mitochondrial light switches: optogenetic approaches to control metabolism. FEBS J 2020; 287:4544-4556. [PMID: 32459870 DOI: 10.1111/febs.15424] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/11/2020] [Accepted: 05/20/2020] [Indexed: 02/06/2023]
Abstract
Developing new technologies to study metabolism is increasingly important as metabolic disease prevalence increases. Mitochondria control cellular metabolism and dynamic changes in mitochondrial function are associated with metabolic abnormalities in cardiovascular disease, cancer, and obesity. However, a lack of precise and reversible methods to control mitochondrial function has prevented moving from association to causation. Recent advances in optogenetics have addressed this challenge, and mitochondrial function can now be precisely controlled in vivo using light. A class of genetically encoded, light-activated membrane channels and pumps has addressed mechanistic questions that promise to provide new insights into how cellular metabolism downstream of mitochondrial function contributes to disease. Here, we highlight emerging reagents-mitochondria-targeted light-activated cation channels or proton pumps-to decrease or increase mitochondrial activity upon light exposure, a technique we refer to as mitochondrial light switches, or mtSWITCH . The mtSWITCH technique is broadly applicable, as energy availability and metabolic signaling are conserved aspects of cellular function and health. Here, we outline the use of these tools in diverse cellular models of disease. We review the molecular details of each optogenetic tool, summarize the results obtained with each, and outline best practices for using optogenetic approaches to control mitochondrial function and downstream metabolism.
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Affiliation(s)
- Brandon J Berry
- Department of Pharmacology and Physiology, University of Rochester Medical Center, NY, USA
| | - Andrew P Wojtovich
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, NY, USA
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13
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Damiani C, Gaglio D, Sacco E, Alberghina L, Vanoni M. Systems metabolomics: from metabolomic snapshots to design principles. Curr Opin Biotechnol 2020; 63:190-199. [PMID: 32278263 DOI: 10.1016/j.copbio.2020.02.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/11/2020] [Accepted: 02/18/2020] [Indexed: 02/07/2023]
Abstract
Metabolomics is a rapidly expanding technology that finds increasing application in a variety of fields, form metabolic disorders to cancer, from nutrition and wellness to design and optimization of cell factories. The integration of metabolic snapshots with metabolic fluxes, physiological readouts, metabolic models, and knowledge-informed Artificial Intelligence tools, is required to obtain a system-level understanding of metabolism. The emerging power of multi-omic approaches and the development of integrated experimental and computational tools, able to dissect metabolic features at cellular and subcellular resolution, provide unprecedented opportunities for understanding design principles of metabolic (dis)regulation and for the development of precision therapies in multifactorial diseases, such as cancer and neurodegenerative diseases.
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Affiliation(s)
- Chiara Damiani
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy; ISBE.IT, SYSBIO Centre of Systems Biology, Piazza della Scienza 2, Milan 20126, Italy
| | - Daniela Gaglio
- ISBE.IT, SYSBIO Centre of Systems Biology, Piazza della Scienza 2, Milan 20126, Italy; Institute of Molecular Bioimaging and Physiology (IBFM), National Research Council (CNR), Segrate, Milan, Italy
| | - Elena Sacco
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy; ISBE.IT, SYSBIO Centre of Systems Biology, Piazza della Scienza 2, Milan 20126, Italy
| | - Lilia Alberghina
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy; ISBE.IT, SYSBIO Centre of Systems Biology, Piazza della Scienza 2, Milan 20126, Italy
| | - Marco Vanoni
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy; ISBE.IT, SYSBIO Centre of Systems Biology, Piazza della Scienza 2, Milan 20126, Italy.
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Glancy B. Visualizing Mitochondrial Form and Function within the Cell. Trends Mol Med 2020; 26:58-70. [PMID: 31706841 PMCID: PMC6938546 DOI: 10.1016/j.molmed.2019.09.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/25/2019] [Accepted: 09/25/2019] [Indexed: 12/12/2022]
Abstract
The specific cellular role of mitochondria is influenced by the surrounding environment because effective mitochondrial function requires the delivery of inputs (e.g., oxygen) and export of products (e.g., signaling molecules) to and from other cellular components, respectively. Recent technological developments in mitochondrial imaging have led to a more precise and comprehensive understanding of the spatial relationships governing the function of this complex organelle, opening a new era of mitochondrial research. Here, I highlight current imaging approaches for visualizing mitochondrial form and function within complex cellular environments. Increasing clarity of mitochondrial behavior within cells will continue to lend mechanistic insights into the role of mitochondria under normal and pathological conditions and point to spatially regulated processes that can be targeted to improve cellular function.
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Affiliation(s)
- Brian Glancy
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA; National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA.
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Ryan TE. Assessing mitochondrial energetics in vivo with molecular detail: the best of both worlds using mitoRACE. J Physiol 2019; 597:5319-5320. [PMID: 31541453 DOI: 10.1113/jp278897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 09/18/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Terence E Ryan
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL, USA.,Center for Exercise Science, University of Florida, Gainesville, FL, USA
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