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Kawamura Y, Oka K, Semba T, Takamori M, Sugiura Y, Yamasaki R, Suzuki Y, Chujo T, Nagase M, Oiwa Y, Fujioka S, Homma S, Yamamura Y, Miyawaki S, Narita M, Fukuda T, Sakai Y, Ishimoto T, Tomizawa K, Suematsu M, Yamamoto T, Bono H, Okano H, Miura K. Cellular senescence induction leads to progressive cell death via the INK4a-RB pathway in naked mole-rats. EMBO J 2023; 42:e111133. [PMID: 37431790 PMCID: PMC10425838 DOI: 10.15252/embj.2022111133] [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: 03/23/2022] [Revised: 05/04/2023] [Accepted: 05/12/2023] [Indexed: 07/12/2023] Open
Abstract
Naked mole-rats (NMRs) have exceptional longevity and are resistant to age-related physiological decline and diseases. Given the role of cellular senescence in aging, we postulated that NMRs possess unidentified species-specific mechanisms to prevent senescent cell accumulation. Here, we show that upon induction of cellular senescence, NMR fibroblasts underwent delayed and progressive cell death that required activation of the INK4a-retinoblastoma protein (RB) pathway (termed "INK4a-RB cell death"), a phenomenon not observed in mouse fibroblasts. Naked mole-rat fibroblasts uniquely accumulated serotonin and were inherently vulnerable to hydrogen peroxide (H2 O2 ). After activation of the INK4a-RB pathway, NMR fibroblasts increased monoamine oxidase levels, leading to serotonin oxidization and H2 O2 production, which resulted in increased intracellular oxidative damage and cell death activation. In the NMR lung, induction of cellular senescence caused delayed, progressive cell death mediated by monoamine oxidase activation, thereby preventing senescent cell accumulation, consistent with in vitro results. The present findings indicate that INK4a-RB cell death likely functions as a natural senolytic mechanism in NMRs, providing an evolutionary rationale for senescent cell removal as a strategy to resist aging.
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Affiliation(s)
- Yoshimi Kawamura
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
- Department of PhysiologyKeio University School of MedicineTokyoJapan
| | - Kaori Oka
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
| | - Takashi Semba
- Gastrointestinal Cancer Biology, International Research Center for Medical Sciences (IRCMS)Kumamoto UniversityKumamotoJapan
| | - Mayuko Takamori
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
| | - Yuki Sugiura
- Department of BiochemistryKeio University School of MedicineTokyoJapan
| | - Riyo Yamasaki
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
| | - Yusuke Suzuki
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
| | - Takeshi Chujo
- Department of Molecular PhysiologyKumamoto UniversityKumamotoJapan
| | - Mari Nagase
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
| | - Yuki Oiwa
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
- Department of Chemical BiologyNational Center for Geriatrics and GerontologyObuJapan
| | - Shusuke Fujioka
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
| | - Sayuri Homma
- Department of PharmacologyHoshi University School of Pharmacy and Pharmaceutical SciencesTokyoJapan
| | - Yuki Yamamura
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
| | - Shingo Miyawaki
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
- Laboratory of Veterinary Surgery, Faculty of Applied Biological SciencesGifu UniversityGifuJapan
| | - Minoru Narita
- Department of PharmacologyHoshi University School of Pharmacy and Pharmaceutical SciencesTokyoJapan
- Division of Cancer PathophysiologyNational Cancer Center Research Institute (NCCRI)TokyoJapan
| | - Takaichi Fukuda
- Department of Anatomy and NeurobiologyKumamoto UniversityKumamotoJapan
| | - Yusuke Sakai
- Department of PathologyNational Institute of Infectious DiseasesTokyoJapan
| | - Takatsugu Ishimoto
- Gastrointestinal Cancer Biology, International Research Center for Medical Sciences (IRCMS)Kumamoto UniversityKumamotoJapan
- Department of Gastroenterological Surgery, Graduate School of Medical SciencesKumamoto UniversityKumamotoJapan
| | - Kazuhito Tomizawa
- Department of Molecular PhysiologyKumamoto UniversityKumamotoJapan
- Center for Metabolic Regulation of Healthy AgingKumamoto UniversityKumamotoJapan
| | - Makoto Suematsu
- Department of BiochemistryKeio University School of MedicineTokyoJapan
- WPI‐Bio2Q Research CenterCentral Institute for Experimental AnimalsKawasakiJapan
| | - Takuya Yamamoto
- Department of Life Science Frontiers, Center for iPS Cell Research and Application (CiRA)Kyoto UniversityKyotoJapan
- Institute for the Advanced Study of Human Biology (WPI‐ASHBi), Kyoto UniversityKyotoJapan
- Medical‐risk Avoidance based on iPS Cells TeamRIKEN Center for Advanced Intelligence Project (AIP)KyotoJapan
| | - Hidemasa Bono
- Laboratory of Genome Informatics, Graduate School of Integrated Sciences for LifeHiroshima UniversityHigashi‐HiroshimaJapan
- Laboratory of BioDX, PtBio Collaborative Research Laboratory, Genome Editing Innovation CenterHiroshima UniversityHigashi‐HiroshimaJapan
| | - Hideyuki Okano
- Department of PhysiologyKeio University School of MedicineTokyoJapan
| | - Kyoko Miura
- Department of Aging and Longevity ResearchKumamoto UniversityKumamotoJapan
- Biomedical Animal Research Laboratory, Institute for Genetic MedicineHokkaido UniversitySapporoJapan
- Department of PhysiologyKeio University School of MedicineTokyoJapan
- Center for Metabolic Regulation of Healthy AgingKumamoto UniversityKumamotoJapan
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Oka K, Yamakawa M, Kawamura Y, Kutsukake N, Miura K. The Naked Mole-Rat as a Model for Healthy Aging. Annu Rev Anim Biosci 2023; 11:207-226. [PMID: 36318672 DOI: 10.1146/annurev-animal-050322-074744] [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] [Indexed: 11/06/2022]
Abstract
Naked mole-rats (NMRs, Heterocephalus glaber) are the longest-lived rodents with a maximum life span exceeding 37 years. They exhibit a delayed aging phenotype and resistance to age-related functional decline/diseases. Specifically, they do not display increased mortality with age, maintain several physiological functions until nearly the end of their lifetime, and rarely develop cancer and Alzheimer's disease. NMRs live in a hypoxic environment in underground colonies in East Africa and are highly tolerant of hypoxia. These unique characteristics of NMRs have attracted considerable interest from zoological and biomedical researchers. This review summarizes previous studies of the ecology, hypoxia tolerance, longevity/delayed aging, and cancer resistance of NMRs and discusses possible mechanisms contributing to their healthy aging. In addition, we discuss current issues and future perspectives to fully elucidate the mechanisms underlying delayed aging and resistance to age-related diseases in NMRs.
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Affiliation(s)
- Kaori Oka
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; , ,
| | - Masanori Yamakawa
- Department of Evolutionary Studies of Biosystems, Sokendai (The Graduate University for Advanced Studies), Kanagawa, Japan; ,
| | - Yoshimi Kawamura
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; , ,
| | - Nobuyuki Kutsukake
- Department of Evolutionary Studies of Biosystems, Sokendai (The Graduate University for Advanced Studies), Kanagawa, Japan; , .,Research Center for Integrative Evolutionary Science, Sokendai (The Graduate University for Advanced Studies), Kanagawa, Japan
| | - Kyoko Miura
- Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; , , .,Center for Metabolic Regulation of Healthy Aging, Kumamoto University, Kumamoto, Japan
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Marks de Chabris NC, Sabir S, Perkins G, Cheng H, Ellisman MH, Pamenter ME. Short communication: Acute hypoxia does not alter mitochondrial abundance in naked mole-rats. Comp Biochem Physiol A Mol Integr Physiol 2023; 276:111343. [PMID: 36379380 DOI: 10.1016/j.cbpa.2022.111343] [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: 08/26/2022] [Revised: 10/20/2022] [Accepted: 11/08/2022] [Indexed: 11/15/2022]
Abstract
Hypoxia poses a significant energetic challenge and most species exhibit metabolic remodelling when exposed to prolonged hypoxia. One component of this remodelling is mitochondrial biogenesis/mitophagy, which alter mitochondrial abundance and helps to adjust metabolic throughput to match changes in energy demands in hypoxia. However, how acute hypoxia impacts mitochondrial abundance in hypoxia-tolerant species is poorly understood. To help address this gap, we exposed hypoxia-tolerant naked mole-rats to 3 h of normoxia or acute hypoxia (5% O2) and measured changes in mitochondrial abundance using two well-established markers: citrate synthase (CS) enzyme activity and mitochondrial DNA (mtDNA) abundance. We found that neither marker changed with hypoxia in brain, liver, or kidney, suggesting that mitochondrial biogenesis is not initiated during acute hypoxia in these tissues. Conversely in skeletal muscle, the ratio of CS activity to total protein decreased 50% with hypoxia. However, this change was likely driven by an increase in soluble protein density in hypoxia because CS activity was unchanged relative to wet tissue weight and the mtDNA copy number was unchanged. To confirm this, we examined skeletal muscle mitochondria using transmission electron microscopy and found no change in mitochondrial volume density. Taken together with previous studies of mitochondrial respiratory function, our present findings suggest that naked mole-rats primarily rely on tissue-specific functional remodelling of metabolic pathways and mitochondrial respiratory throughput, and not physical changes in mitochondrial number or volume, to adjust to short-term hypoxic exposure.
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Affiliation(s)
| | - Soulene Sabir
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Hang Cheng
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Marc H Ellisman
- National Center for Microscopy and Imaging Research, Department of Neurosciences, University of California San Diego, La Jolla, CA, USA
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada; University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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Yap KN, Wong HS, Ramanathan C, Rodriguez-Wagner CA, Roberts MD, Freeman DA, Buffenstein R, Zhang Y. Naked mole-rat and Damaraland mole-rat exhibit lower respiration in mitochondria, cellular and organismal levels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148582. [PMID: 35667393 DOI: 10.1016/j.bbabio.2022.148582] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 05/30/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Naked mole-rats (NMR) and Damaraland mole-rats (DMR) exhibit extraordinary longevity for their body size, high tolerance to hypoxia and oxidative stress and high reproductive output; these collectively defy the concept that life-history traits should be negatively correlated. However, when life-history traits share similar underlying physiological mechanisms, these may be positively associated with each other. We propose that one such potential common mechanism might be the bioenergetic properties of mole-rats. Here, we aim to characterize the bioenergetic properties of two African mole-rats. We adopted a top-down perspective measuring the bioenergetic properties at the organismal, cellular, and molecular level in both species and the biological significance of these properties were compared with the same measures in Siberian hamsters and C57BL/6 mice, chosen for their similar body size to the mole-rat species. We found mole-rats shared several bioenergetic properties that differed from their comparison species, including low basal metabolic rates, a high dependence on glycolysis rather than on oxidative phosphorylation for ATP production, and low proton conductance across the mitochondrial inner membrane. These shared mole-rat features could be a result of evolutionary adaptation to tolerating variable oxygen atmospheres, in particular hypoxia, and may in turn be one of the molecular mechanisms underlying their extremely long lifespans.
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Affiliation(s)
- Kang Nian Yap
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, United States of America; Department of Biology, Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Hoi Shan Wong
- Calico Life Sciences LLC, South San Francisco, CA 94080, United States of America
| | - Chidambaram Ramanathan
- College of Health Sciences, University of Memphis, Memphis, TN 38152, United States of America
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, United States of America
| | - David A Freeman
- Department of Biological Science, University of Memphis, Memphis, TN 38152, United States of America
| | - Rochelle Buffenstein
- Calico Life Sciences LLC, South San Francisco, CA 94080, United States of America.
| | - Yufeng Zhang
- College of Health Sciences, University of Memphis, Memphis, TN 38152, United States of America.
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D’Alessio S, Cheng H, Eaton L, Kraev I, Pamenter ME, Lange S. Acute Hypoxia Alters Extracellular Vesicle Signatures and the Brain Citrullinome of Naked Mole-Rats (Heterocephalus glaber). Int J Mol Sci 2022; 23:ijms23094683. [PMID: 35563075 PMCID: PMC9100269 DOI: 10.3390/ijms23094683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 02/04/2023] Open
Abstract
Peptidylarginine deiminases (PADs) and extracellular vesicles (EVs) may be indicative biomarkers of physiological and pathological status and adaptive responses, including to diseases and disorders of the central nervous system (CNS) and related to hypoxia. While these markers have been studied in hypoxia-intolerant mammals, in vivo investigations in hypoxia-tolerant species are lacking. Naked mole-rats (NMR) are among the most hypoxia-tolerant mammals and are thus a good model organism for understanding natural and beneficial adaptations to hypoxia. Thus, we aimed to reveal CNS related roles for PADs in hypoxia tolerance and identify whether circulating EV signatures may reveal a fingerprint for adaptive whole-body hypoxia responses in this species. We found that following in vivo acute hypoxia, NMR: (1) plasma-EVs were remodelled, (2) whole proteome EV cargo contained more protein hits (including citrullinated proteins) and a higher number of associated KEGG pathways relating to the total proteome of plasma-EVs Also, (3) brains had a trend for elevation in PAD1, PAD3 and PAD6 protein expression, while PAD2 and PAD4 were reduced, while (4) the brain citrullinome had a considerable increase in deiminated protein hits with hypoxia (1222 vs. 852 hits in normoxia). Our findings indicate that circulating EV signatures are modified and proteomic content is reduced in hypoxic conditions in naked mole-rats, including the circulating EV citrullinome, while the brain citrullinome is elevated and modulated in response to hypoxia. This was further reflected in elevation of some PADs in the brain tissue following acute hypoxia treatment. These findings indicate a possible selective role for PAD-isozymes in hypoxia response and tolerance.
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Affiliation(s)
- Stefania D’Alessio
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6 UW, UK;
| | - Hang Cheng
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
| | - Liam Eaton
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
| | - Igor Kraev
- Electron Microscopy Suite, Faculty of Science, Technology, Engineering and Mathematics, Open University, Walton Hall, Milton Keynes MK7 6AA, UK;
| | - Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; (H.C.); (L.E.); (M.E.P.)
- Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Sigrun Lange
- Tissue Architecture and Regeneration Research Group, School of Life Sciences, College of Liberal Arts and Sciences, University of Westminster, London W1W 6 UW, UK;
- Correspondence: ; Tel.: +44-(0)-20-7911-5000 (ext. 64832)
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Abstract
ABSTRACT
Hypoxia is one of the strongest environmental drivers of cellular and physiological adaptation. Although most mammals are largely intolerant of hypoxia, some specialized species have evolved mitigative strategies to tolerate hypoxic niches. Among the most hypoxia-tolerant mammals are naked mole-rats (Heterocephalus glaber), a eusocial species of subterranean rodent native to eastern Africa. In hypoxia, naked mole-rats maintain consciousness and remain active despite a robust and rapid suppression of metabolic rate, which is mediated by numerous behavioural, physiological and cellular strategies. Conversely, hypoxia-intolerant mammals and most other hypoxia-tolerant mammals cannot achieve the same degree of metabolic savings while staying active in hypoxia and must also increase oxygen supply to tissues, and/or enter torpor. Intriguingly, recent studies suggest that naked mole-rats share many cellular strategies with non-mammalian vertebrate champions of anoxia tolerance, including the use of alternative metabolic end-products and potent pH buffering mechanisms to mitigate cellular acidification due to upregulation of anaerobic metabolic pathways, rapid mitochondrial remodelling to favour increased respiratory efficiency, and systemic shifts in energy prioritization to maintain brain function over that of other tissues. Herein, I discuss what is known regarding adaptations of naked mole-rats to a hypoxic lifestyle, and contrast strategies employed by this species to those of hypoxia-intolerant mammals, closely related African mole-rats, other well-studied hypoxia-tolerant mammals, and non-mammalian vertebrate champions of anoxia tolerance. I also discuss the neotenic theory of hypoxia tolerance – a leading theory that may explain the evolutionary origins of hypoxia tolerance in mammals – and highlight promising but underexplored avenues of hypoxia-related research in this fascinating model organism.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7. University of Ottawa, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada, K1H 8M5
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Huynh KW, Pamenter ME. Lactate inhibits naked mole-rat cardiac mitochondrial respiration. J Comp Physiol B 2022; 192:501-511. [PMID: 35181821 DOI: 10.1007/s00360-022-01430-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 01/13/2022] [Accepted: 01/29/2022] [Indexed: 12/25/2022]
Abstract
In aerobic conditions, the proton-motive force drives oxidative phosphorylation (OXPHOS) and the conversion of ADP to ATP. In hypoxic environments, OXPHOS is impaired, resulting in energy shortfalls and the accumulation of protons and lactate. This results in cellular acidification, which may impact the activity and/or integrity of mitochondrial enzymes and in turn negatively impact mitochondrial respiration and thus aerobic ATP production. Naked mole-rats (NMRs) are among the most hypoxia-tolerant mammals and putatively experience intermittent hypoxia in their underground burrows. However, if and how NMR cardiac mitochondria are impacted by lactate accumulation in hypoxia is unknown. We predicted that lactate alters mitochondrial respiration in NMR cardiac muscle. To test this, we used high-resolution respirometry to measure mitochondrial respiration in permeabilized cardiac muscle fibres from NMRs exposed to 4 h of in vivo normoxia (21% O2) or hypoxia (7% O2). We found that: (1) cardiac mitochondria cannot directly oxidize lactate, but surprisingly, (2) lactate inhibits mitochondrial respiration, and (3) decreases complex IV maximum respiratory capacity. Finally, (4) in vivo hypoxic exposure decreases the magnitude of lactate-mediated inhibition of mitochondrial respiration. Taken together, our results suggest that lactate may retard electron transport system function in NMR cardiac mitochondria, particularly in normoxia, and that NMR hearts may be primed for anaerobic metabolism.
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Affiliation(s)
- Kenny W Huynh
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada
| | - Matthew E Pamenter
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt., Ottawa, ON, K1N 6N5, Canada. .,University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
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Metabolomic Analysis of Carbohydrate and Amino Acid Changes Induced by Hypoxia in Naked Mole-Rat Brain and Liver. Metabolites 2022; 12:metabo12010056. [PMID: 35050178 PMCID: PMC8779284 DOI: 10.3390/metabo12010056] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 12/20/2022] Open
Abstract
Hypoxia poses a major physiological challenge for mammals and has significant impacts on cellular and systemic metabolism. As with many other small rodents, naked mole-rats (NMRs; Heterocephalus glaber), who are among the most hypoxia-tolerant mammals, respond to hypoxia by supressing energy demand (i.e., through a reduction in metabolic rate mediated by a variety of cell- and tissue-level strategies), and altering metabolic fuel use to rely primarily on carbohydrates. However, little is known regarding specific metabolite changes that underlie these responses. We hypothesized that NMR tissues utilize multiple strategies in responding to acute hypoxia, including the modulation of signalling pathways to reduce anabolism and reprogram carbohydrate metabolism. To address this question, we evaluated changes of 64 metabolites in NMR brain and liver following in vivo hypoxia exposure (7% O2, 4 h). We also examined changes in matched tissues from similarly treated hypoxia-intolerant mice. We report that, following exposure to in vivo hypoxia: (1) phenylalanine, tyrosine and tryptophan anabolism are supressed both in NMR brain and liver; (2) carbohydrate metabolism is reprogramed in NMR brain and liver, but in a divergent manner; (3) redox state is significantly altered in NMR brain; and (4) the AMP/ATP ratio is elevated in liver. Overall, our results suggest that hypoxia induces significant metabolic remodelling in NMR brain and liver via alterations of multiple metabolic pathways.
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Temperature sensitivity differs between heart and red muscle mitochondria in mahi-mahi (Coryphaena hippurus). Sci Rep 2020; 10:14865. [PMID: 32913250 PMCID: PMC7484784 DOI: 10.1038/s41598-020-71741-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 08/10/2020] [Indexed: 11/08/2022] Open
Abstract
Maintaining energy balance over a wide range of temperatures is critical for an active pelagic fish species such as the mahi-mahi (Coryphaena hippurus), which can experience rapid changes in temperature during vertical migrations. Due to the profound effect of temperature on mitochondrial function, this study was designed to investigate the effects of temperature on mitochondrial respiration in permeabilized heart and red skeletal muscle (RM) fibres isolated from mahi-mahi. As RM is thought to be more anatomically isolated from rapid ambient temperature changes compared to the myocardium, it was hypothesized that heart mitochondria would be more tolerant of temperature changes through a greater ability to match respiratory capacity to an increase in temperature and to maintain coupling, when compared to RM mitochondria. Results show that heart fibres were more temperature sensitive and increased respiration rate with temperature increases to a greater degree than RM. Respiratory coupling ratios at the three assay temperatures (20, 26, and 30 °C), revealed that heart mitochondria were less coupled at a lower temperature (26 °C) compared to RM mitochondria (30 °C). In response to an in vitro acute temperature challenge, both tissues showed irreversible effects, where both heart and RM increased uncoupling whether the assay temperature was acutely changed from 20 to 30 °C or 30 to 20 °C. The findings from this study indicate that mahi-mahi heart mitochondria were more temperature sensitive compared to those from RM.
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