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Martin TG, Leinwand LA. Molecular regulation of reversible cardiac remodeling: lessons from species with extreme physiological adaptations. J Exp Biol 2024; 227:jeb247445. [PMID: 39344503 PMCID: PMC11463965 DOI: 10.1242/jeb.247445] [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] [Indexed: 10/01/2024]
Abstract
Some vertebrates evolved to have a remarkable capacity for anatomical and physiological plasticity in response to environmental challenges. One example of such plasticity can be found in the ambush-hunting snakes of the genus Python, which exhibit reversible cardiac growth with feeding. The predation strategy employed by pythons is associated with months-long fasts that are arrested by ingestion of large prey. Consequently, digestion compels a dramatic increase in metabolic rate and hypertrophy of multiple organs, including the heart. In this Review, we summarize the post-prandial cardiac adaptations in pythons at the whole-heart, cellular and molecular scales. We highlight circulating factors and cellular signaling pathways that are altered during digestion to affect cardiac form and function and propose possible mechanisms that may drive the post-digestion regression of cardiac mass. Adaptive physiological cardiac hypertrophy has also been observed in other vertebrates, including in fish acclimated to cold water, birds flying at high altitudes and exercising mammals. To reveal potential evolutionarily conserved features, we summarize the molecular signatures of reversible cardiac remodeling identified in these species and compare them with those of pythons. Finally, we offer a perspective on the potential of biomimetics targeting the natural biology of pythons as therapeutics for human heart disease.
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Affiliation(s)
- Thomas G. Martin
- Molecular, Cellular, and Developmental Biology Department, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Leslie A. Leinwand
- Molecular, Cellular, and Developmental Biology Department, University of Colorado Boulder, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA
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Yang Y, Hao Z, An N, Han Y, Miao W, Storey KB, Lefai E, Liu X, Wang J, Liu S, Xie M, Chang H. Integrated transcriptomics and metabolomics reveal protective effects on heart of hibernating Daurian ground squirrels. J Cell Physiol 2023; 238:2724-2748. [PMID: 37733616 DOI: 10.1002/jcp.31123] [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: 08/04/2023] [Revised: 09/02/2023] [Accepted: 09/08/2023] [Indexed: 09/23/2023]
Abstract
Hibernating mammals are natural models of resistance to ischemia, hypoxia-reperfusion injury, and hypothermia. Daurian ground squirrels (spermophilus dauricus) can adapt to endure multiple torpor-arousal cycles without sustaining cardiac damage. However, the molecular regulatory mechanisms that underlie this adaptive response are not yet fully understood. This study investigates morphological, functional, genetic, and metabolic changes that occur in the heart of ground squirrels in three groups: summer active (SA), late torpor (LT), and interbout arousal (IBA). Morphological and functional changes in the heart were measured using hematoxylin-eosin (HE) staining, Masson staining, echocardiography, and enzyme-linked immunosorbent assay (ELISA). Results showed significant changes in cardiac function in the LT group as compared with SA or IBA groups, but no irreversible damage occurred. To understand the molecular mechanisms underlying these phenotypic changes, transcriptomic and metabolomic analyses were conducted to assess differential changes in gene expression and metabolite levels in the three groups of ground squirrels, with a focus on GO and KEGG pathway analysis. Transcriptomic analysis showed that differentially expressed genes were involved in the remodeling of cytoskeletal proteins, reduction in protein synthesis, and downregulation of the ubiquitin-proteasome pathway during hibernation (including LT and IBA groups), as compared with the SA group. Metabolomic analysis revealed increased free amino acids, activation of the glutathione antioxidant system, altered cardiac fatty acid metabolic preferences, and enhanced pentose phosphate pathway activity during hibernation as compared with the SA group. Combining the transcriptomic and metabolomic data, active mitochondrial oxidative phosphorylation and creatine-phosphocreatine energy shuttle systems were observed, as well as inhibition of ferroptosis signaling pathways during hibernation as compared with the SA group. In conclusion, these results provide new insights into cardio-protection in hibernators from the perspective of gene and metabolite changes and deepen our understanding of adaptive cardio-protection mechanisms in mammalian hibernators.
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Affiliation(s)
- Yingyu Yang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Ziwei Hao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Ning An
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Yuting Han
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Weilan Miao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Etienne Lefai
- INRAE, Unité de Nutrition Humaine, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Xiaoxuan Liu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Junshu Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Shuo Liu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Manjiang Xie
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, Shaanxi, China
| | - Hui Chang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
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Vásquez-Trincado C, Patel M, Sivaramakrishnan A, Bekeová C, Anderson-Pullinger L, Wang N, Tang HY, Seifert EL. Adaptation of the heart to Frataxin depletion: Evidence that integrated stress response can predominate over mTORC1 activation. Hum Mol Genet 2021; 33:ddab216. [PMID: 34550363 PMCID: PMC11000666 DOI: 10.1093/hmg/ddab216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 11/12/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an inherited disorder caused by depletion of frataxin (FXN), a mitochondrial protein required for iron-sulfur cluster (ISC) biogenesis. Cardiac dysfunction is the main cause of death. Yet pathogenesis, and, more generally, how the heart adapts to FXN loss, remain poorly understood, though are expected to be linked to an energy deficit. We modified a transgenic (TG) mouse model of inducible FXN depletion that permits phenotypic evaluation of the heart at different FXN levels, and focused on substrate-specific bioenergetics and stress signaling. When FXN protein in the TG heart was 17% of normal, bioenergetics and signaling were not different from control. When, 8 weeks later, FXN was ~ 97% depleted in the heart, TG heart mass and cardiomyocyte cross-sectional area were less, without evidence of fibrosis or apoptosis. mTORC1 signaling was activated, as was the integrated stress response, evidenced by greater phosphorylation of eIF2α relative to total eIF2α, and decreased protein translation. We interpret these results to suggest that, in TG hearts, an anabolic stimulus was constrained by eIF2α phosphorylation. Cardiac contractility was maintained in the 97%-FXN-depleted hearts, possibly contributed by an unexpected preservation of β-oxidation, though pyruvate oxidation was lower. Bioenergetics alterations were matched by changes in the mitochondrial proteome, including a non-uniform decrease in abundance of ISC-containing proteins. Altogether, these findings suggest that the FXN depleted heart can suppress a major ATP demanding process such as protein translation, which, together with some preservation of β-oxidation, could be adaptive, at least in the short term.
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Affiliation(s)
- César Vásquez-Trincado
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Monika Patel
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Aishwarya Sivaramakrishnan
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Carmen Bekeová
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Lauren Anderson-Pullinger
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Nadan Wang
- Center for Translational Medicine, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Hsin-Yao Tang
- Proteomics and Metabolomics Facility, The Wistar Institute, Philadelphia, PA 19104, United States
| | - Erin L Seifert
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
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Tessier SN, Ingelson-Filpula WA, Storey KB. Epigenetic regulation by DNA methyltransferases during torpor in the thirteen-lined ground squirrel Ictidomys tridecemlineatus. Mol Cell Biochem 2021; 476:3975-3985. [PMID: 34191233 DOI: 10.1007/s11010-021-04214-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 06/21/2021] [Indexed: 12/31/2022]
Abstract
The thirteen-lined ground squirrel, Ictidomys tridecemlineatus, is a mammal capable of lowering its Tb to almost 0 °C while undergoing deep torpor bouts over the winter. To decrease its metabolic rate to such a drastic extent, the squirrel must undergo multiple physiological, biological, and molecular alterations including downregulation of almost all nonessential processes. Epigenetic regulation allows for a dynamic range of transient phenotypes, allowing the squirrel to downregulate energy-expensive and nonessential pathways during torpor. DNA methylation is a prominent form of epigenetic regulation; therefore, the DNA methyltransferase (DNMT) family of enzymes were studied by measuring expression and activity levels of the five major proteins during torpor bouts. Additionally, specific cytosine marks on genomic DNA were quantified to further elucidate DNA methylation during hibernation. A tissue-specific response was observed that highlighted variant degrees of DNA methylation and DNMT expression/activity, demonstrating that DNA methylation is a highly complex form of epigenetic regulation and likely one of many regulatory mechanisms that enables metabolic rate depression in response to torpor.
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Affiliation(s)
- Shannon N Tessier
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.,BioMEMS Resource Center & Center for Engineering in Medicine, Massachusetts General Hospital & Harvard Medical School, 114 16th Street, Charlestown, MA, 02129, USA
| | - W Aline Ingelson-Filpula
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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Popova S, Ulanova A, Gritsyna Y, Salmov N, Rogachevsky V, Mikhailova G, Bobylev A, Bobyleva L, Yutskevich Y, Morenkov O, Zakharova N, Vikhlyantsev I. Predominant synthesis of giant myofibrillar proteins in striated muscles of the long-tailed ground squirrel Urocitellus undulatus during interbout arousal. Sci Rep 2020; 10:15185. [PMID: 32938992 PMCID: PMC7495002 DOI: 10.1038/s41598-020-72127-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
Abstract
Molecular mechanisms underlying muscle-mass retention during hibernation have been extensively discussed in recent years. This work tested the assumption that protein synthesis hyperactivation during interbout arousal of the long-tailed ground squirrel Urocitellus undulatus should be accompanied by increased calpain-1 activity in striated muscles. Calpain-1 is known to be autolysed and activated in parallel. Western blotting detected increased amounts of autolysed calpain-1 fragments in the heart (1.54-fold, p < 0.05) and m. longissimus dorsi (1.8-fold, p < 0.01) of ground squirrels during interbout arousal. The total protein synthesis rate determined by SUnSET declined 3.67-fold in the heart (p < 0.01) and 2.96-fold in m. longissimus dorsi (p < 0.01) during interbout arousal. The synthesis rates of calpain-1 substrates nebulin and titin in muscles did not differ during interbout arousal from those in active summer animals. A recovery of the volume of m. longissimus dorsi muscle fibres, a trend towards a heart-muscle mass increase and a restoration of the normal titin content (reduced in the muscles during hibernation) were observed. The results indicate that hyperactivation of calpain-1 in striated muscles of long-tailed ground squirrels during interbout arousal is accompanied by predominant synthesis of giant sarcomeric cytoskeleton proteins. These changes may contribute to muscle mass retention during hibernation.
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Affiliation(s)
- Svetlana Popova
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Anna Ulanova
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Yulia Gritsyna
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Nikolay Salmov
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Vadim Rogachevsky
- Laboratory of Signal Perception Mechanisms, Institute of Cell Biophysics, FRC PSCBR, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Gulnara Mikhailova
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Alexander Bobylev
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Liya Bobyleva
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Yana Yutskevich
- Kuban State University, Krasnodar, Krasnodar Krai, 350040, Russia
| | - Oleg Morenkov
- Laboratory of Cell Culture and Tissue Engineering, Institute of Cell Biophysics, FRC PSCBR, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Nadezda Zakharova
- Laboratory of Natural and Artificial Hypobiosis Mechanisms, Institute of Cell Biophysics, FRC PSCBR, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Ivan Vikhlyantsev
- Laboratory of the Structure and Functions of Muscle Proteins, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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Al-Attar R, Storey KB. Suspended in time: Molecular responses to hibernation also promote longevity. Exp Gerontol 2020; 134:110889. [PMID: 32114078 DOI: 10.1016/j.exger.2020.110889] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/20/2020] [Accepted: 02/21/2020] [Indexed: 12/16/2022]
Abstract
Aging in most animals is an inevitable process that causes or is a result of physiological, biochemical, and molecular changes in the body, and has a strong influence on an organism's lifespan. Although advancement in medicine has allowed humans to live longer, the prevalence of age-associated medical complications is continuously burdening older adults worldwide. Current animal models used in research to study aging have provided novel information that has helped investigators understand the aging process; however, these models are limiting. Aging is a complex process that is regulated at multiple biological levels, and while a single manipulation in these models can provide information on a process, it is not enough to understand the global regulation of aging. Some mammalian hibernators live up to 9.8-times higher than their expected average lifespan, and new research attributes this increase to their ability to hibernate. A common theme amongst these mammalian hibernators is their ability to greatly reduce their metabolic rate to a fraction of their normal rate and initiate cytoprotective responses that enable their survival. Metabolic rate depression is strictly regulated at different biological levels in order to enable the animal to not only survive, but to also do so by relying mainly on their limited internal fuels. As such, understanding both the global and specific regulatory mechanisms used to promote survival during hibernation could, in theory, allow investigators to have a better understanding of the aging process. This can also allow pharmaceutical industries to find therapeutics that could delay or reverse age-associated medical complications and promote healthy aging and longevity in humans.
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Affiliation(s)
- Rasha Al-Attar
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
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Childers CL, Tessier SN, Storey KB. The heart of a hibernator: EGFR and MAPK signaling in cardiac muscle during the hibernation of thirteen-lined ground squirrels, Ictidomys tridecemlineatus. PeerJ 2019; 7:e7587. [PMID: 31534849 PMCID: PMC6732209 DOI: 10.7717/peerj.7587] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/30/2019] [Indexed: 12/18/2022] Open
Abstract
Background Thirteen-lined ground squirrels (Ictidomys tridecemlineatus) experience dramatic changes in physiological and molecular parameters during winter hibernation. Notably, these animals experience reduced blood circulation during torpor, which can put numerous stresses on their hearts. The present study evaluates the role played by the epidermal growth factor receptor (EGFR) in signal transduction during hibernation at low body temperature to evaluate signaling mechanisms. By investigating the regulation of intracellular mitogen activated protein kinase (MAPK) pathway responses, anti-apoptosis signals, downstream transcription factors, and heat shock proteins in cardiac muscle we aim to determine the correlation between upstream tyrosine phosphorylation events and downstream outcomes. Methods Protein abundance of phosphorylated EGFR, MAPKs and downstream effector proteins were quantified using immunoblotting and Luminex® multiplex assays. Results Monitoring five time points over the torpor/arousal cycle, EGFR phosphorylation on T654, Y1068, Y1086 was found to increase significantly compared with euthermic control values particularly during the arousal process from torpor, whereas phosphorylation at Y1045 was reduced during torpor. Phosphorylation of intracellular MAPK targets (p-ERK 1/2, p-JNK, p-p38) also increased strongly during the early arousal stage with p-p38 levels also rising during prolonged torpor. However, of downstream MAPK effector kinases that were measured, only p-Elk-1 levels changed showing a decrease during interbout arousal (IA). Apoptosis markers revealed a strong reduction of the pro-apoptotic p-BAD protein during entrance into torpor that remained suppressed through torpor and IA. However, active caspase-9 protein rose strongly during IA. Levels of p-AKT were suppressed during the transition phases into and out of torpor. Of four heat shock proteins assessed, only HSP27 protein levels changed significantly (a 40% decrease) during torpor. Conclusion We show evidence of EGFR phosphorylation correlating to activation of MAPK signaling and downstream p-ELK1 suppression during hibernation. We also demonstrate a reduction in p-BAD mediated pro-apoptotic signaling during hibernation with active caspase-9 protein levels increasing only during IA. I. tridecemlineatus has natural mechanisms of tissue protection during hibernation that is largely due to cellular regulation through phosphorylation-mediated signaling cascade. We identify a possible link between EGFR and MAPK signaling via p-ERK, p-p38, and p-JNK in the cardiac muscle of these hibernating mammals that correlates with an apparent reduction in caspase-9 apoptotic signaling. This reveals a piece of the mechanism behind how these mammals are resilient to cardiac stresses during hibernation that would otherwise be damaging.
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Affiliation(s)
| | - Shannon N Tessier
- BioMEMS Resource Center & Center for Engineering in Medicine, Massachusetts General Hospital & Harvard Medical School, Charlestown, MA, USA
| | - Kenneth B Storey
- Institute of Biochemistry, Department of Biology and Chemistry, Carleton University, Ottawa, ON, Canada
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Wu X, Pan B, Liu L, Zhao W, Zhu J, Huang X, Tian J. In utero exposure to PM2.5 during gestation caused adult cardiac hypertrophy through histone acetylation modification. J Cell Biochem 2018; 120:4375-4384. [PMID: 30269375 DOI: 10.1002/jcb.27723] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/29/2018] [Indexed: 01/27/2023]
Affiliation(s)
- Xiaoqi Wu
- Heart Centre, Children’s Hospital of Chongqing Medical University Chongqing China
- Key Laboratory of Developmental Disease in Childhood (Chongqing Medical University), Ministry of Education Chongqing China
- Key Laboratory of Pediatrics Chongqing China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders Chongqing China
| | - Bo Pan
- Heart Centre, Children’s Hospital of Chongqing Medical University Chongqing China
- Key Laboratory of Developmental Disease in Childhood (Chongqing Medical University), Ministry of Education Chongqing China
- Key Laboratory of Pediatrics Chongqing China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders Chongqing China
| | - Lingjuan Liu
- Key Laboratory of Developmental Disease in Childhood (Chongqing Medical University), Ministry of Education Chongqing China
- Key Laboratory of Pediatrics Chongqing China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders Chongqing China
| | - Weian Zhao
- Heart Centre, Children’s Hospital of Chongqing Medical University Chongqing China
- Key Laboratory of Developmental Disease in Childhood (Chongqing Medical University), Ministry of Education Chongqing China
- Key Laboratory of Pediatrics Chongqing China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders Chongqing China
| | - Jing Zhu
- Key Laboratory of Developmental Disease in Childhood (Chongqing Medical University), Ministry of Education Chongqing China
- Key Laboratory of Pediatrics Chongqing China
- Chongqing International Science and Technology Cooperation Center for Child Development and Disorders Chongqing China
| | - Xupei Huang
- Department of Biomedical Science Charlie E. Schmidt College of Medicine, Florida Atlantic University Boca Raton Florida
| | - Jie Tian
- Heart Centre, Children’s Hospital of Chongqing Medical University Chongqing China
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Agmatine modulates calcium handling in cardiomyocytes of hibernating ground squirrels through calcium-sensing receptor signaling. Cell Signal 2018; 51:1-12. [PMID: 30030121 DOI: 10.1016/j.cellsig.2018.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 11/20/2022]
Abstract
True hibernators are remarkable group of mammals whose hearts are resistant to such stressors as deep hypothermia, ischemia, arrhythmia. Capability of cardiac cells from hibernating species to effectively rule Ca2+ homeostasis during torpor is poorly studied. Better understanding of these mechanisms could allow to introduce new strategies for improvement the cardiac performance and may be useful for cardiovascular medicine. Here for the first time we have shown that the regulation of Ca2+ handling and thereby cardiomyocyte contractility by endogenous neurotransmitter agmatine occurs through the modulation of calcium-sensing receptor (CaSR). In isolated cardiocytes of hibernating ground squirrels generating stationary Ca2+ transients in the absence of actual myocellular excitation, low doses of this polyamine (up to 500 μM) induce the Gβγ-dependent activation of PI3-kinase with subsequent stimulation of Akt-kinase and nitric oxide (NO) production by endothelial NO-synthase (eNOS). NO production abolishes Ca2+ oscillations in virtue of the enhancement of Ca2+ reuptake by sarco(endo)plasmic Ca2+ ATPase (SERCA). Simultaneously, the activation of phospholipase A2 (PLA2) and arachidonic-acid dependent Ca2+ entry occur providing replenishment of Ca2+ store. High concentrations of agmatine (> 2 mM) induce other CaSR-mediated pathways involving phospholipase C (PLC) pathway, the formation of inositoltriphosphate (IP3) and diacylglicerol (DAG) followed by induction of their targets: IP3 receptors and protein kinase C isoforms (PKC), respectively. Furthermore, it is also responsible for the stimulation of PLA2 and elevation of intracellular calcium caused by arachidonic acid-regulated Ca2+-permeable (ARC) channels. Additionally, there is a potent store-operated Ca2+ entry (SOC) in cardiomyocyte. Negative (NPS 2143) and positive (R 568) allosteric modulators of CaSR recapitulate effects of low and high agmatine doses on Ca2+ handling and NO synthesis. These facts and the alteration of agmatine influence in response to an increase of extracellular Ca2+, which is the direct agonist of CaSR, may confirm the participation of CaSR in regulation of Ca2+ handling and excitability of cardiomyocytes by agmatine.
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Wiersma M, Beuren TMA, de Vrij EL, Reitsema VA, Bruintjes JJ, Bouma HR, Brundel BJJM, Henning RH. Torpor-arousal cycles in Syrian hamster heart are associated with transient activation of the protein quality control system. Comp Biochem Physiol B Biochem Mol Biol 2018; 223:23-28. [PMID: 29894736 DOI: 10.1016/j.cbpb.2018.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/28/2018] [Accepted: 06/04/2018] [Indexed: 12/14/2022]
Abstract
Hibernation consists of torpor, with marked suppression of metabolism and physiological functions, alternated with arousal periods featuring their full restoration. The heart is particularly challenged, exemplified by its rate reduction from 400 to 5-10 beats per minute during torpor in Syrian hamsters. In addition, during arousals, the heart needs to accommodate the very rapid return to normal function, which lead to our hypothesis that cardiac function during hibernation is supported by maintenance of protein homeostasis through adaptations in the protein quality control (PQC) system. Hereto, we examined autophagy, the endoplasmic reticulum (ER) unfolded protein (UPRER) response and the heat shock response (HSR) in Syrian hamster hearts during torpor and arousal. Transition from torpor to arousal (1.5 h) was associated with stimulation of the PQC system during early arousal, demonstrated by induction of autophagosomes, as shown by an increase in LC3B-II protein abundance, likely related to the activation of the UPRER during late torpor in response to proteotoxic stress. The HSR was not activated during torpor or arousal. Our results demonstrate activation of the cardiac PQC system - particularly autophagosomal degradation - in early arousal in response to cardiac stress, to clear excess aberrant or damaged proteins, being gradually formed during the torpor bout and/or the rapid increase in heart rate during the transition from torpor to arousal. This mechanism may enable the large gain in cardiac function during the transition from torpor to arousal, which may hold promise to further understand 'hibernation' of cardiomyocytes in human heart disease.
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Affiliation(s)
- Marit Wiersma
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands; Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands.
| | - Thais M A Beuren
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands; Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands
| | - Edwin L de Vrij
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands; Department of Surgery, Martini Hospital, Groningen, The Netherlands
| | - Vera A Reitsema
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands
| | - Jantje J Bruintjes
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands
| | - Hjalmar R Bouma
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands; Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bianca J J M Brundel
- Department of Physiology, Amsterdam Cardiovascular Sciences, VU University Medical Center, Amsterdam, The Netherlands; Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands
| | - Robert H Henning
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, The Netherlands
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Peter AK, Crocini C, Leinwand LA. Expanding our scientific horizons: utilization of unique model organisms in biological research. EMBO J 2017; 36:2311-2314. [PMID: 28694243 DOI: 10.15252/embj.201797640] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Angela K Peter
- Department of Molecular, Cellular and Developmental Biology, Biofrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Claudia Crocini
- Department of Molecular, Cellular and Developmental Biology, Biofrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Leslie A Leinwand
- Department of Molecular, Cellular and Developmental Biology, Biofrontiers Institute, University of Colorado, Boulder, CO, USA
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12
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Lindstedt S, Nishikawa K. Huxleys’ Missing Filament: Form and Function of Titin in Vertebrate Striated Muscle. Annu Rev Physiol 2017; 79:145-166. [DOI: 10.1146/annurev-physiol-022516-034152] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stan Lindstedt
- Center for Bioengineering Innovation, Northern Arizona University, Flagstaff, Arizona 86011-4185
| | - Kiisa Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011-4185;
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13
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Zhang Y, Aguilar OA, Storey KB. Transcriptional activation of muscle atrophy promotes cardiac muscle remodeling during mammalian hibernation. PeerJ 2016; 4:e2317. [PMID: 27602284 PMCID: PMC4991874 DOI: 10.7717/peerj.2317] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 07/12/2016] [Indexed: 12/12/2022] Open
Abstract
Background. Mammalian hibernation in thirteen-lined ground squirrels (Ictidomys tridecemlineatus) is characterized by dramatic changes on a physiological and molecular level. During hibernation, mammalian hearts show a propensity to hypertrophy due to the need for increasing contractility to pump colder and more viscous blood. While cardiac hypertrophy is quite often a process characterized by decompensation, the ground squirrel studied is an excellent model of cardiac plasticity and cardioprotection under conditions of hypothermia and ischemia. The forkhead box O (Foxo) family of proteins and myogenin (MyoG) are transcription factors that control protein degradation and muscle atrophy by regulating the expression of the E3 ubiquitin ligases, MAFbx and MuRF1. These ligases are part of the ubiquitin proteasome system by transferring ubiquitin to proteins and targeting these proteins for degradation. Regulation of Foxo1 and 3a occurs through phosphorylation at different residues. The threonine-24 (Thr-24) and serine-319 (Ser-319) residues on Foxo1, and the Thr-32 residue on Foxo3a are phosphorylated by Akt, leading to cytoplasmic localization of Foxo. We propose that the described mechanism contributes to the changes taking place in cardiac muscle throughout hibernation. Methods. Total and phosphorylated protein levels of Foxo1 and Foxo3a, as well as total protein levels of MyoG, MAFbx, and MuRF1, were studied using immunoblotting. Results. Immunoblotting results demonstrated upregulations in Foxo1 and Foxo3a total protein levels (1.3- and 4.5-fold increases relative to euthermic control, for Foxo1 and 3a respectively) during late torpor, and protein levels remained elevated throughout the rest of torpor and at interbout arousal. We also observed decreases in inactive, phosphorylated Foxo1 and 3a proteins during throughout torpor, where levels of p-Foxo1 Ser319 and Thr24, as well as p-Foxo3a Thr32 decreased by at least 45% throughout torpor. MyoG was upregulated only during late torpor by 2.4-fold. Protein levels of MAFbx and MuRF1 increased in late torpor as well as during early arousal by as much as 2.8-fold, and MAFbx levels remained elevated during interbout arousal, whereas MuRF1 levels returned to control levels. Discussion. The present results indicate that upregulation and activation of Foxo1 and 3a, in addition to the increase in MyoG levels at late torpor, may be upregulating the expression of MAFbx and MuRF1. These findings suggest that there is activation of the ubiquitin proteasome system (UPS) as ground squirrels arouse from torpor. Therefore, the signalling pathway involving MyoG, and the E3 ligases MAFbx and MuRF1, plays a significant role in cardiac muscle remodelling during hibernation. These findings provide insights into the regulation of protein degradation and turnover in the cardiac muscle of a hibernator model.
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Affiliation(s)
- Yichi Zhang
- Institute of Biochemistry and Department of Biology, Carleton University , Ottawa , ON , Canada
| | - Oscar A Aguilar
- Institute of Biochemistry and Department of Biology, Carleton University , Ottawa , ON , Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University , Ottawa , ON , Canada
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14
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Wu CW, Biggar KK, Luu BE, Szereszewski KE, Storey KB. Analysis of microRNA expression during the torpor-arousal cycle of a mammalian hibernator, the 13-lined ground squirrel. Physiol Genomics 2016; 48:388-96. [PMID: 27084747 DOI: 10.1152/physiolgenomics.00005.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/04/2016] [Indexed: 01/06/2023] Open
Abstract
Hibernation is a highly regulated stress response that is utilized by some mammals to survive harsh winter conditions and involves a complex metabolic reprogramming at the cellular level to maintain tissue protections at low temperature. In this study, we profiled the expression of 117 conserved microRNAs in the heart, muscle, and liver of the 13-lined ground squirrel (Ictidomys tridecemlineatus) across four stages of the torpor-arousal cycle (euthermia, early torpor, late torpor, and interbout arousal) by real-time PCR. We found significant differential regulation of numerous microRNAs that were both tissue specific and torpor stage specific. Among the most significant regulated microRNAs was miR-208b, a positive regulator of muscle development that was found to be upregulated by fivefold in the heart during late torpor (13-fold during arousal), while decreased by 3.7-fold in the skeletal muscle, implicating a potential regulatory role in the development of cardiac hypertrophy and skeletal muscle atrophy in the ground squirrels during torpor. In addition, the insulin resistance marker miR-181a was upregulated by 5.7-fold in the liver during early torpor, which supports previous suggestions of hyperinsulinemia in hibernators during the early stages of the hibernation cycle. Although microRNA expression profiles were largely unique between the three tissues, GO annotation analysis revealed that the putative targets of upregulated microRNAs tend to enrich toward suppression of progrowth-related processes in all three tissues. These findings implicate microRNAs in the regulation of both tissue-specific processes and general suppression of cell growth during hibernation.
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Affiliation(s)
- Cheng-Wei Wu
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Kyle K Biggar
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Bryan E Luu
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Kama E Szereszewski
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada
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15
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Zena LA, Dantonio V, Gargaglioni LH, Andrade DV, Abe AS, Bícego KC. Winter metabolic depression does not change arterial baroreflex control of heart rate in the tegu lizard (Salvator merianae). J Exp Biol 2016; 219:725-33. [DOI: 10.1242/jeb.129130] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 12/17/2015] [Indexed: 11/20/2022]
Abstract
Baroreflex regulation of blood pressure (BP) is important for maintaining appropriate tissue perfusion. Although temperature affects heart rate (fH) reflex regulation in some reptiles and toads, no data are available on the influence of temperature-independent metabolic states on baroreflex. The South American tegu lizard Salvator merianae exhibits a clear seasonal cycle of activity decreasing fH along with winter metabolic downregulation, independent of body temperature. Through pharmacological interventions (phenylephrine and sodium nitroprusside), the baroreflex control of fH was studied at ∼25°C in spring-summer and winter-acclimated tegus.
In winter lizards, resting and minimum fH were lower than in spring-summer animals (respectively, 13.3±0.82 vs 10.3±0.81 and 11.2±0.65 vs 7.97±0.88 beats.min−1), while no acclimation differences occurred in resting BP (5.14±0.38 vs 5.06±0.56 kPa), baroreflex gain (94.3±10.7 vs 138.7±30.3 %.kPa−1) and rate-pressure product (an index of myocardial activity). Vagal tone exceeded the sympathetic tone of fH especially in the winter group. Therefore, despite the lower fH, winter acclimation does not diminish the fH baroreflex responses nor rate-pressure product possibly because of increased stroke volume that may arise due to heart hypertrophy. Independent of acclimation, fH responded more to hypotension than to hypertension. This should imply that tegus, which have no pressure separation within the single heart ventricle, must have other protection mechanisms against pulmonary hypertension or oedema, presumably through lymphatic drainage and/or vagal vasoconstriction of pulmonary artery. Such a predominant fH reflex response to hypothension, previously observed in anurans, crocodilians and mammals, may be a common feature of tetrapods.
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Affiliation(s)
- Lucas A. Zena
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, 14884-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
| | - Valter Dantonio
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, 14884-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
| | - Luciane H. Gargaglioni
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, 14884-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
| | - Denis V. Andrade
- Department of Zoology, Institute of Bioscience, São Paulo State University, Rio Claro, São Paulo, 13506-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
| | - Augusto S. Abe
- Department of Zoology, Institute of Bioscience, São Paulo State University, Rio Claro, São Paulo, 13506-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
| | - Kênia C. Bícego
- Department of Animal Morphology and Physiology, College of Agricultural and Veterinarian Sciences, São Paulo State University, Jaboticabal, São Paulo, 14884-900, Brazil
- National Institute of Science and Technology – Comparative Physiology (INCT- Fisiologia Comparada), Brazil
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16
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Zhang Y, Storey KB. Expression of nuclear factor of activated T cells (NFAT) and downstream muscle-specific proteins in ground squirrel skeletal and heart muscle during hibernation. Mol Cell Biochem 2015; 412:27-40. [PMID: 26597853 DOI: 10.1007/s11010-015-2605-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 11/14/2015] [Indexed: 10/22/2022]
Abstract
The thirteen-lined ground squirrel (Ictidomys tridecemlineatus) undergoes remarkable adaptive changes during hibernation. Interestingly, skeletal muscle remodelling occurs during the torpor-arousal cycle of hibernation to prevent net muscle loss despite inactivity. Reversible cardiomyocyte hypertrophy occurs in cardiac muscle, allowing the heart to preserve cardiac output during hibernation, while avoiding chronic maladaptive hypertrophy post-hibernation. We propose that calcium signalling proteins [calcineurin (Cn), calmodulin (CaM), and calpain], the nuclear factor of activated T cell (NFAT) family of transcription factors, and the NFAT targets myoferlin and myomaker contribute significantly to adaptations taking place in skeletal and cardiac muscle during hibernation. Protein-level analyses were performed over several conditions: euthermic room temperature (ER), euthermic cold room (EC), entrance into (EN), early (ET), and late torpor (LT) time points, in addition to early (EA), interbout (IA), and late arousal (LA) time points using immunoblotting and DNA-protein interaction (DPI) enzyme-linked immunosorbent assay (ELISAs). In skeletal and cardiac muscle, NFATc2 protein levels were elevated during torpor. NFATc4 increased throughout the torpor-arousal cycle in both tissues, and NFATc1 showed this trend in cardiac muscle only. NFATc3 showed an elevation in DNA-binding activity but not expression during torpor. Myoferlin protein levels dramatically increased during torpor in both skeletal and cardiac muscle. Myomaker levels also increased significantly in cardiac muscle during torpor. Cardiac Cn levels remained stable, whereas CaM and calpain decreased throughout the torpor-arousal cycle. Activation and/or upregulation of NFATc2, c3, myoferlin, and myomaker at torpor could be part of a stress-response mechanism to preserve skeletal muscle mass, whereas CaM and calpain appear to initiate the rapid reversal of cardiac hypertrophy during arousal through downregulation of the NFAT-Cn pathway.
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Affiliation(s)
- Yichi Zhang
- Department of Biology, Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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17
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Vermillion KL, Jagtap P, Johnson JE, Griffin TJ, Andrews MT. Characterizing Cardiac Molecular Mechanisms of Mammalian Hibernation via Quantitative Proteogenomics. J Proteome Res 2015; 14:4792-804. [DOI: 10.1021/acs.jproteome.5b00575] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Katie L. Vermillion
- Department
of Biology, University of Minnesota Duluth, 1035 Kirby Drive, Duluth, Minnesota 55812, United States
| | - Pratik Jagtap
- Center
for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner
Avenue, St. Paul, Minnesota 55108, United States
- Department
of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church St SE, Minneapolis, Minnesota 55455, United States
| | - James E. Johnson
- Minnesota Supercomputing Institute, 512 Walter Library 117 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Timothy J. Griffin
- Center
for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner
Avenue, St. Paul, Minnesota 55108, United States
- Department
of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church St SE, Minneapolis, Minnesota 55455, United States
| | - Matthew T. Andrews
- Department
of Biology, University of Minnesota Duluth, 1035 Kirby Drive, Duluth, Minnesota 55812, United States
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18
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Ratigan ED, McKay DB. Exploring principles of hibernation for organ preservation. Transplant Rev (Orlando) 2015; 30:13-9. [PMID: 26613668 DOI: 10.1016/j.trre.2015.08.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 08/19/2015] [Accepted: 08/30/2015] [Indexed: 11/25/2022]
Abstract
Interest in mimicking hibernating states has led investigators to explore the biological mechanisms that permit hibernating mammals to survive for months at extremely low ambient temperatures, with no food or water, and awaken from their hibernation without apparent organ injury. Hibernators have evolved mechanisms to adapt to dramatic reductions in core body temperature and metabolic rate, accompanied by prolonged periods without nutritional intake and at the same time tolerate the metabolic demands of arousal. This review discusses the inherent resilience of hibernators to kidney injury and provides a potential framework for new therapies targeting ex vivo preservation of kidneys for transplantation.
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Affiliation(s)
- Emmett D Ratigan
- Division of Nephrology/Hypertension, Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - Dianne B McKay
- Division of Nephrology/Hypertension, Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, USA.
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19
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Buffenstein R, Nelson OL, Corbit KC. Questioning the preclinical paradigm: natural, extreme biology as an alternative discovery platform. Aging (Albany NY) 2015; 6:913-20. [PMID: 25553771 PMCID: PMC4276785 DOI: 10.18632/aging.100704] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The pace at which science continues to advance is astonishing. From cosmology, microprocessors, structural engineering, and DNA sequencing our lives are continually affected by science-based technology. However, progress in treating human ailments, especially age-related conditions such as cancer and Alzheimer's disease, moves at a relative snail's pace. Given that the amount of investment is not disproportionately low, one has to question why our hopes for the development of efficacious drugs for such grievous illnesses have been frustratingly unrealized. Here we discuss one aspect of drug development –rodent models – and propose an alternative approach to discovery research rooted in evolutionary experimentation. Our goal is to accelerate the conversation around how we can move towards more translative preclinical work.
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Affiliation(s)
- Rochelle Buffenstein
- Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, TX University of Texas Health Science Center at San Antonio, TX USA
| | - O Lynne Nelson
- Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 9916, USA
| | - Kevin C Corbit
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA 91360, USA
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20
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Vermillion KL, Anderson KJ, Hampton M, Andrews MT. Gene expression changes controlling distinct adaptations in the heart and skeletal muscle of a hibernating mammal. Physiol Genomics 2015; 47:58-74. [PMID: 25572546 PMCID: PMC4346737 DOI: 10.1152/physiolgenomics.00108.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/05/2015] [Indexed: 01/12/2023] Open
Abstract
Throughout the hibernation season, the thirteen-lined ground squirrel (Ictidomys tridecemlineatus) experiences extreme fluctuations in heart rate, metabolism, oxygen consumption, and body temperature, along with prolonged fasting and immobility. These conditions necessitate different functional requirements for the heart, which maintains contractile function throughout hibernation, and the skeletal muscle, which remains largely inactive. The adaptations used to maintain these contractile organs under such variable conditions serves as a natural model to study a variety of medically relevant conditions including heart failure and disuse atrophy. To better understand how two different muscle tissues maintain function throughout the extreme fluctuations of hibernation we performed Illumina HiSeq 2000 sequencing of cDNAs to compare the transcriptome of heart and skeletal muscle across the circannual cycle. This analysis resulted in the identification of 1,076 and 1,466 differentially expressed genes in heart and skeletal muscle, respectively. In both heart and skeletal muscle we identified a distinct cold-tolerant mechanism utilizing peroxisomal metabolism to make use of elevated levels of unsaturated depot fats. The skeletal muscle transcriptome also shows an early increase in oxidative capacity necessary for the altered fuel utilization and increased oxygen demand of shivering. Expression of the fetal gene expression profile is used to maintain cardiac tissue, either through increasing myocyte size or proliferation of resident cardiomyocytes, while skeletal muscle function and mass are protected through transcriptional regulation of pathways involved in protein turnover. This study provides insight into how two functionally distinct muscles maintain function under the extreme conditions of mammalian hibernation.
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Affiliation(s)
- Katie L Vermillion
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Kyle J Anderson
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
| | - Marshall Hampton
- Department of Mathematics and Statistics, University of Minnesota Duluth, Duluth, Minnesota
| | - Matthew T Andrews
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota; and
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21
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Nelson OL, Robbins CT. Cardiovascular function in large to small hibernators: bears to ground squirrels. J Comp Physiol B 2014; 185:265-79. [PMID: 25542162 DOI: 10.1007/s00360-014-0881-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 11/25/2014] [Accepted: 12/02/2014] [Indexed: 01/19/2023]
Abstract
Mammalian hibernation has intrigued scientists due to extreme variations in normal seasonal physiological homeostasis. Numerous species manifest a hibernation phenotype although the characteristics of the hypometabolic state can be quite different. Ground squirrels (e.g., Sciuridae) are often considered the prototypical hibernator as individuals in this genus transition from an active, euthermic state (37 °C) to a nonresponsive hibernating state where torpid body temperature commonly falls to 3-5 °C. However, the hibernating state is not continuous as periodic warming and arousals occur. In contrast, the larger hibernators of genus Ursus are less hypothermic (body temperatures decline from approximately 37°-33 °C), are more reactive, and cyclical arousals do not occur. Both species dramatically reduce cardiac output during hibernation from the active state (bears ~75 % reduction in bears and ~97 % reduction in ground squirrels), and both species demonstrate hypokinetic atrial chamber activity. However, there are several important differences in cardiac function between the two groups during hibernation. Left ventricular diastolic filling volumes and stroke volumes do not differ in bears between seasons, but increased diastolic and stroke volumes during hibernation are important contributors to cardiac output in ground squirrels. Decreased cardiac muscle mass and increased ventricular stiffness have been found in bears, whereas ground squirrels have increased cardiac muscle mass and decreased ventricular stiffness during hibernation. Molecular pathways of cardiac muscle plasticity reveal differences between the species in the modification of sarcomeric proteins such as titin and α myosin heavy chain during hibernation. The differences in hibernation character are likely to account for the alternative cardiac phenotypes and functional strategies manifested by the two species. Molecular investigation coupled with better knowledge of seasonal physiological alterations is dramatically advancing our understanding of small and large hibernators and their evolutionary differences.
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Affiliation(s)
- O Lynne Nelson
- Department of Veterinary Clinical Sciences, Washington State University, 100 Grimes Way, Pullman, WA, 99164, USA,
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22
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Currie SE, Noy K, Geiser F. Passive rewarming from torpor in hibernating bats: minimizing metabolic costs and cardiac demands. Am J Physiol Regul Integr Comp Physiol 2014; 308:R34-41. [PMID: 25411363 DOI: 10.1152/ajpregu.00341.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Endothermic arousal from torpor is an energetically costly process and imposes enormous demands on the cardiovascular system, particularly during early stage arousal from low body temperature (Tb). To minimize these costs many bats and other heterothermic endotherms rewarm passively from torpor using solar radiation or fluctuating ambient temperature (Ta). Because the heart plays a critical role in the arousal process in terms of blood distribution and as a source of heat production, it is desirable to understand how the function of this organ responds to passive rewarming and how this relates to changes in metabolism and Tb. We investigated heart rate (HR) in hibernating long-eared bats (Nyctophilus gouldi) and its relationship to oxygen consumption (V̇o₂) and subcutaneous temperature (Tsub) during exposure to increasing Ta compared with endogenous arousals at constant low Ta. During passive rewarming, HR and V̇o₂ remained low over a large Tsub range and increased concurrently with increasing Ta (Q₁₀ 2.4 and 2.5, respectively). Absolute values were higher than during steady-state torpor but below those measured during torpor entry. During active arousals, mean HR and V̇o₂ were substantially higher than during passive rewarming at corresponding Tsub. In addition, partial passive rewarming reduced the cost of arousal from torpor by 53% compared with entirely active arousal. Our data show that passive rewarming considerably reduces arousal costs and arousal time; we suggest this may also contribute to minimizing exposure to oxidative stresses as well as demands on the cardiovascular system.
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Affiliation(s)
- Shannon E Currie
- Centre for Behavioral and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Kodie Noy
- Centre for Behavioral and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Fritz Geiser
- Centre for Behavioral and Physiological Ecology, Zoology, University of New England, Armidale, Australia
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