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Naranjo M, Breedon SA, Storey KB. Cardiac microRNA expression profile in response to estivation. Biochimie 2023:S0300-9084(23)00001-9. [PMID: 36627041 DOI: 10.1016/j.biochi.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/09/2023]
Abstract
Couch's spadefoot toad (Scaphiopus couchii) spends most of the year underground in a hypometabolic state known as estivation. During this time, they overcome significant dehydration and lack of food through many mechanisms including employing metabolic rate depression (MRD), increasing urea concentration, switching to lipid oxidation as the primary energy source, and decreasing their breathing and heart rate. MicroRNA (miRNA) are known to regulate translation by targeting messenger RNA (mRNA) for degradation or temporary storage, with several studies having reported that miRNA is differentially expressed during MRD, including estivation. Thus, we hypothesized that miRNA would be involved in gene regulation during estivation in S. couchii heart. Next-generation sequencing and bioinformatic analyses were used to assess changes in miRNA expression in response to two-month estivation and to predict the downstream effects of this expression. KEGG and GO analyses indicated that ribosome and cardiac muscle contraction are among the pathways predicted to be upregulated, whereas cell signaling and fatty acid metabolism were predicted to be downregulated. Together these results suggest that miRNAs contribute to the regulation of gene expression related to cardiac muscle physiology and energy metabolism during estivation.
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Affiliation(s)
- Mairelys Naranjo
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6
| | - Sarah A Breedon
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6.
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2
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Mancardi D, Ottolenghi S, Attanasio U, Tocchetti CG, Paroni R, Pagliaro P, Samaja M. Janus, or the Inevitable Battle Between Too Much and Too Little Oxygen. Antioxid Redox Signal 2022; 37:972-989. [PMID: 35412859 DOI: 10.1089/ars.2021.0232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Significance: Oxygen levels are key regulators of virtually every living mammalian cell, under both physiological and pathological conditions. Starting from embryonic and fetal development, through the growth, onset, and progression of diseases, oxygen is a subtle, although pivotal, mediator of key processes such as differentiation, proliferation, autophagy, necrosis, and apoptosis. Hypoxia-driven modifications of cellular physiology are investigated in depth or for their clinical and translational relevance, especially in the ischemic scenario. Recent Advances: The mild or severe lack of oxygen is, undoubtedly, related to cell death, although abundant evidence points at oscillating oxygen levels, instead of permanent low pO2, as the most detrimental factor. Different cell types can consume oxygen at different rates and, most interestingly, some cells can shift from low to high consumption according to the metabolic demand. Hence, we can assume that, in the intracellular compartment, oxygen tension varies from low to high levels depending on both supply and consumption. Critical Issues: The positive balance between supply and consumption leads to a pro-oxidative environment, with some cell types facing hypoxia/hyperoxia cycles, whereas some others are under fairly constant oxygen tension. Future Directions: Within this frame, the alterations of oxygen levels (dysoxia) are critical in two paradigmatic organs, the heart and brain, under physiological and pathological conditions and the interactions of oxygen with other physiologically relevant gases, such as nitric oxide, can alternatively contribute to the worsening or protection of ischemic organs. Further, the effects of dysoxia are of pivotal importance for iron metabolism. Antioxid. Redox Signal. 37, 972-989.
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Affiliation(s)
- Daniele Mancardi
- Department of Clinical and Biological Sciences, University of Torino, Turin, Italy
| | - Sara Ottolenghi
- Department of Health Sciences, University of Milano, Milan, Italy
- School of Medicine and Surgery, University of Milano Bicocca, Milan, Italy
| | - Umberto Attanasio
- Cardio-Oncology Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Carlo Gabriele Tocchetti
- Cardio-Oncology Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy
- Interdepartmental Center for Clinical and Translational Research (CIRCET), Federico II University, Naples, Italy
- Interdepartmental Hypertension Research Center (CIRIAPA), Federico II University, Naples, Italy
- Center for Basic and Clinical Immunology Research (CISI), Federico II University, Naples, Italy
| | - Rita Paroni
- Department of Health Sciences, University of Milano, Milan, Italy
| | - Pasquale Pagliaro
- Department of Clinical and Biological Sciences, University of Torino, Turin, Italy
| | - Michele Samaja
- Department of Health Sciences, University of Milano, Milan, Italy
- MAGI GROUP, San Felice del Benaco, Italy
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3
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Tessier SN, Breedon SA, Storey KB. Modulating Nrf2 transcription factor activity: Revealing the regulatory mechanisms of antioxidant defenses during hibernation in 13-lined ground squirrels. Cell Biochem Funct 2021; 39:623-635. [PMID: 33624895 DOI: 10.1002/cbf.3627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 11/09/2022]
Abstract
Mammalian hibernators undergo major behavioural, physiological and biochemical changes to survive hypothermia, ischaemia-reperfusion and finite fuel reserves during days or weeks of continuous torpor. During hibernation, the 13-lined ground squirrel (Ictidomys tridecemlineatus) undergoes a global suppression of energetically expensive processes such as transcription and translation, while selectively upregulating certain genes/proteins to mitigate torpor-related damage. Antioxidant defenses are critical for preventing damage caused by reactive oxygen species (ROS) during torpor and arousal, and Nrf2 is a critical regulator of these antioxidant genes. This study analysed the relative protein expression levels of Nrf2, KEAP1, small Mafs (MafF, MafK and MafG) and catalase and the regulation of Nrf2 transcription factors by post-translational modifications (PTMs) and protein-protein interactions with a negative regulator (KEAP1) during hibernation. It was found that a significant increase in MafK during late torpor predicated an increase in relative Nrf2 and catalase levels seen in arousal. Additionally, Nrf2-KEAP1 protein-protein interactions and Nrf2 PTMs, including serine phosphorylation and lysine acetylation, were responsive to cycles of torpor-arousal with peak responses occurring during arousal. These peaks seen during arousal correspond to a surge in oxygen consumption, which causes increased ROS production. Thus, these regulatory mechanisms could be important during hibernation because they provide mechanisms for mitigating the deleterious effects of oxidative stress by modifying Nrf2 expression and function in an energetically inexpensive manner.
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Affiliation(s)
- Shannon N Tessier
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada.,BioMEMS Resource Center & Center for Engineering in Medicine and Surgery, Massachusetts General Hospital & Harvard Medical School, Charlestown, Massachusetts, USA
| | - Sarah A Breedon
- 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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4
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Nespolo RF, Gaitan-Espitia JD, Quintero-Galvis JF, Fernandez FV, Silva AX, Molina C, Storey KB, Bozinovic F. A functional transcriptomic analysis in the relict marsupial Dromiciops gliroides
reveals adaptive regulation of protective functions during hibernation. Mol Ecol 2018; 27:4489-4500. [DOI: 10.1111/mec.14876] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 09/05/2018] [Accepted: 09/07/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Roberto F. Nespolo
- Instituto de Ciencias Ambientales y Evolutivas; Facultad de Ciencias; Universidad Austral de Chile; Valdivia Chile
- Departamento de Ecología; Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
- Millennium Institute for Integrative Biology (iBio); Santiago Chile
| | - Juan Diego Gaitan-Espitia
- The Swire Institute of Marine Science and School of Biological Sciences; The University of Hong Kong; Hong Kong SAR China
- CSIRO Oceans & Atmosphere; Hobart Tasmania Australia
| | - Julian F. Quintero-Galvis
- Instituto de Ciencias Ambientales y Evolutivas; Facultad de Ciencias; Universidad Austral de Chile; Valdivia Chile
| | - Fernanda V. Fernandez
- Instituto de Fisiología; Facultad de Medicina; Universidad Austral de Chile; Valdivia Chile
| | - Andrea X. Silva
- AUSTRALomics, Vicerrectoría de Investigación, Desarrollo y Creación Artística; Universidad Austral de Chile; Valdivia Chile
| | - Cristian Molina
- AUSTRALomics, Vicerrectoría de Investigación, Desarrollo y Creación Artística; Universidad Austral de Chile; Valdivia Chile
| | - Kenneth B. Storey
- Department of Biology and Institute of Biochemistry; Carleton University; Ottawa Ontario Canada
| | - Francisco Bozinovic
- Departamento de Ecología; Center of Applied Ecology and Sustainability (CAPES); Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile; Santiago Chile
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5
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Hadj-Moussa H, Green SR, Storey KB. The Living Dead: Mitochondria and Metabolic Arrest. IUBMB Life 2018; 70:1260-1266. [PMID: 30230676 DOI: 10.1002/iub.1910] [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: 05/31/2018] [Revised: 06/17/2018] [Accepted: 06/19/2018] [Indexed: 12/26/2022]
Abstract
Mitochondria are not just the powerhouses of the cell; these 'end of function' organelles are crucial components of cellular physiology and influence many central metabolic and signaling pathways that support complex multicellular life. Not surprisingly, these organelles play vital roles in adaptations for extreme survival strategies including hibernation and freeze tolerance, both of which are united by requirements for a strong reduction and reprioritization of metabolic processes. To facilitate metabolic rate depression, adaptations of all aspects of mitochondrial function are required, including; energetics, physiology, abundance, gene regulation, and enzymatic controls. This review discusses these factors with a focus on the stress-specific nature of mitochondrial genes and transcriptional regulators, and processes including apoptosis and chaperone protein responses. We also analyze the regulation of glutamate dehydrogenase and pyruvate dehydrogenase, central mitochondrial enzymes involved in coordinating the shifts in metabolic fuel use associated with extreme survival strategies. Finally, an emphasis is given to the novel mitochondrial research areas of microRNAs, peptides, epigenetics, and gaseous mediators and their potential roles in facilitating hypometabolism. © 2018 IUBMB Life, 70(12):1260-1266, 2018.
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Affiliation(s)
- Hanane Hadj-Moussa
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
| | - Stuart R Green
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
| | - Kenneth B Storey
- Department of Biology and Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
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6
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Stancic A, Jankovic A, Korac A, Cirovic D, Otasevic V, Storey KB, Korac B. A lesson from the oxidative metabolism of hibernator heart: Possible strategy for cardioprotection. Comp Biochem Physiol B Biochem Mol Biol 2018; 219-220:1-9. [PMID: 29501789 DOI: 10.1016/j.cbpb.2018.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/13/2018] [Accepted: 02/22/2018] [Indexed: 01/20/2023]
Abstract
In the present study we hypothesized that myocardial adaptive phenotype in mammalian hibernation involves rearrangement of mitochondria bioenergetic pathways providing protective pattern in states of reduced metabolism and low temperature. European ground squirrels (Spermophilus citellus) were exposed to low temperature (4 ± 1 °C) and then divided into two groups: (1) animals that fell into torpor (hibernating group) and (2) animals that stayed active and euthermic for 1, 3, 7, 12, or 21 days (cold-exposed group). Protein levels of selected components of the electron transport chain and ATP synthase in the heart increased after prolonged cold acclimation (mainly from day 7-21 of cold exposure) and during hibernation. Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was also upregulated under both cold exposure and hibernating conditions. The phosphorylation state (Thr172) of 5'-AMP-activated protein kinase α increased early in cold exposure (at day 1 and 3) along with increased protein levels of phosphofructokinase and pyruvate dehydrogenase, whereas hypoxia inducible factor 1α protein levels showed no changes in response to cold exposure or hibernation. Hibernation also resulted in protein upregulation of three antioxidant defense enzymes (manganese and copper/zinc superoxide dismutases and glutathione peroxidase) and thioredoxin in the heart. Cold-exposed and hibernation-related phenotypes of the heart are characterized by improved molecular basis for mitochondrial energy-producing and antioxidant capacities that are achieved in a controlled manner. The recapitulation of such adaptive mechanisms found in hibernators could have broad application for myocardial protection from ishemia/reperfusion to improve hypothermic survival and cold preservation of hearts from non-hibernating species, including humans.
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Affiliation(s)
- Ana Stancic
- University of Belgrade, Institute for Biological Research "Sinisa Stankovic", Belgrade, Serbia
| | - Aleksandra Jankovic
- University of Belgrade, Institute for Biological Research "Sinisa Stankovic", Belgrade, Serbia
| | - Aleksandra Korac
- University of Belgrade, Faculty of Biology, Centre for Electron Microscopy, Belgrade, Serbia
| | - Dusko Cirovic
- University of Belgrade, Faculty of Biology, Belgrade, Serbia
| | - Vesna Otasevic
- University of Belgrade, Institute for Biological Research "Sinisa Stankovic", Belgrade, Serbia
| | - Kenneth B Storey
- Carleton University, Department of Biology, Ottawa, Ontario, Canada
| | - Bato Korac
- University of Belgrade, Institute for Biological Research "Sinisa Stankovic", Belgrade, Serbia.
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7
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Logan SM, Storey KB. Tissue-specific response of carbohydrate-responsive element binding protein (ChREBP) to mammalian hibernation in 13-lined ground squirrels. Cryobiology 2016; 73:103-11. [PMID: 27614289 DOI: 10.1016/j.cryobiol.2016.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 08/31/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022]
Abstract
Mammalian hibernation is characterized by a general suppression of energy expensive processes and a switch to lipid oxidation as the primary fuel source. Glucose-responsive carbohydrate responsive element binding protein (ChREBP) has yet to be studied in hibernating organisms, which prepare for the cold winter months by feeding until they exhibit an obesity-like state that is accompanied by naturally-induced and completely reversible insulin resistance. Studying ChREBP expression and activity in the hibernating 13-lined ground squirrel is important to better understand the molecular mechanisms that regulate energy metabolism under cellular stress. Immunoblotting was used to determine the relative expression level and subcellular localization of ChREBP, as well as serine phosphorylation at 95 kDa, comparing euthermic and late torpid ground squirrel liver, kidney, heart and muscle. DNA-binding ELISAs and RT-PCR were used to explore ChREBP transcriptional activity during cold stress. ChREBP activity seemed generally suppressed in liver and kidney. During torpor, ChREBP total protein levels decreased to 44% of EC in liver, phosphoserine levels increased 2.1-fold of EC in kidney, and downstream Fasn/Pkl transcript levels decreased to <60% of EC in liver. By contrast, ChREBP activity generally increased during torpor in cardiac and skeletal muscle, where ChREBP total protein levels increased over 1.5-fold and 5-fold of EC in muscle and heart, respectively; where DNA-binding increased by ∼2-fold of EC in muscle; and where Fasn transcript levels increased over 3-fold and 7-fold in both muscle and heart, respectively. In summary, ChREBP has a tissue-specific role in regulating energy metabolism during hibernation.
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Affiliation(s)
- Samantha M Logan
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada.
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8
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Inhibition of skeletal muscle atrophy during torpor in ground squirrels occurs through downregulation of MyoG and inactivation of Foxo4. Cryobiology 2016; 73:112-9. [PMID: 27593478 DOI: 10.1016/j.cryobiol.2016.08.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 08/15/2016] [Accepted: 08/31/2016] [Indexed: 12/20/2022]
Abstract
Foxo4 and MyoG proteins regulate the transcription of numerous genes, including the E3 ubiquitin ligases MAFbx and MuRF1, which are activated in skeletal muscle under atrophy-inducing conditions. In the thirteen-lined ground squirrel, there is little muscle wasting that occurs during hibernation, a process characterized by bouts of torpor and arousal, despite virtual inactivity. Consequently, we were interested in studying the regulatory role of Foxo4 and MyoG on ubiquitin ligases throughout torpor-arousal cycles. Findings indicate that MAFbx and MuRF1 decreased during early torpor (ET) by 42% and 40%, respectively, relative to euthermic control (EC), although MuRF1 expression subsequently increased at late torpor (LT). The expression pattern of MyoG most closely resembled that of MAFbx, with levels decreasing during LT. In addition, the phosphorylation of Foxo4 at Thr-451 showed an initial increase during EN, followed by a decline throughout the remainder of the torpor-arousal cycle, suggesting Foxo4 inhibition. This trend was mirrored by inhibition of the Ras-Ral pathway, as the Ras and Ral proteins were decreased by 77% and 41% respectively, at ET. Foxo4 phosphorylation at S197 was depressed during entrance and torpor, suggesting Foxo4 nuclear localization, and possibly regulating the increase in MuRF1 levels at LT. These findings indicate that signaling pathways involved in regulating muscle atrophy, such as MyoG and Foxo4 through the Ras-Ral pathway, contribute to important muscle-specific changes during hibernation. Therefore, this data provides novel insight into the molecular mechanisms regulating muscle remodeling in a hibernator model.
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9
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Tessier SN, Storey KB. Lessons from mammalian hibernators: molecular insights into striated muscle plasticity and remodeling. Biomol Concepts 2016; 7:69-92. [DOI: 10.1515/bmc-2015-0031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/21/2016] [Indexed: 12/19/2022] Open
Abstract
AbstractStriated muscle shows an amazing ability to adapt its structural apparatus based on contractile activity, loading conditions, fuel supply, or environmental factors. Studies with mammalian hibernators have identified a variety of molecular pathways which are strategically regulated and allow animals to endure multiple stresses associated with the hibernating season. Of particular interest is the observation that hibernators show little skeletal muscle atrophy despite the profound metabolic rate depression and mechanical unloading that they experience during long weeks of torpor. Additionally, the cardiac muscle of hibernators must adjust to low temperature and reduced perfusion, while the strength of contraction increases in order to pump cold, viscous blood. Consequently, hibernators hold a wealth of knowledge as it pertains to understanding the natural capacity of myocytes to alter structural, contractile and metabolic properties in response to environmental stimuli. The present review outlines the molecular and biochemical mechanisms which play a role in muscular atrophy, hypertrophy, and remodeling. In this capacity, four main networks are highlighted: (1) antioxidant defenses, (2) the regulation of structural, contractile and metabolic proteins, (3) ubiquitin proteosomal machinery, and (4) macroautophagy pathways. Subsequently, we discuss the role of transcription factors nuclear factor (erythroid-derived 2)-like 2 (Nrf2), Myocyte enhancer factor 2 (MEF2), and Forkhead box (FOXO) and their associated posttranslational modifications as it pertains to regulating each of these networks. Finally, we propose that comparing and contrasting these concepts to data collected from model organisms able to withstand dramatic changes in muscular function without injury will allow researchers to delineate physiological versus pathological responses.
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Affiliation(s)
- Shannon N. Tessier
- 1Department of Surgery and Center for Engineering in Medicine, Massachusetts General Hospital and Harvard Medical School, Building 114 16th Street, Charlestown, MA 02129, USA
| | - Kenneth B. Storey
- 2Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa K1S 5B6, Ontario, Canada
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Abstract
Extended bouts of fasting are ingrained in the ecology of many organisms, characterizing aspects of reproduction, development, hibernation, estivation, migration, and infrequent feeding habits. The challenge of long fasting episodes is the need to maintain physiological homeostasis while relying solely on endogenous resources. To meet that challenge, animals utilize an integrated repertoire of behavioral, physiological, and biochemical responses that reduce metabolic rates, maintain tissue structure and function, and thus enhance survival. We have synthesized in this review the integrative physiological, morphological, and biochemical responses, and their stages, that characterize natural fasting bouts. Underlying the capacity to survive extended fasts are behaviors and mechanisms that reduce metabolic expenditure and shift the dependency to lipid utilization. Hormonal regulation and immune capacity are altered by fasting; hormones that trigger digestion, elevate metabolism, and support immune performance become depressed, whereas hormones that enhance the utilization of endogenous substrates are elevated. The negative energy budget that accompanies fasting leads to the loss of body mass as fat stores are depleted and tissues undergo atrophy (i.e., loss of mass). Absolute rates of body mass loss scale allometrically among vertebrates. Tissues and organs vary in the degree of atrophy and downregulation of function, depending on the degree to which they are used during the fast. Fasting affects the population dynamics and activities of the gut microbiota, an interplay that impacts the host's fasting biology. Fasting-induced gene expression programs underlie the broad spectrum of integrated physiological mechanisms responsible for an animal's ability to survive long episodes of natural fasting.
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Affiliation(s)
- Stephen M Secor
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Hannah V Carey
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
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11
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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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12
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Yuan L, Geiser F, Lin B, Sun H, Chen J, Zhang S. Down but Not Out: The Role of MicroRNAs in Hibernating Bats. PLoS One 2015; 10:e0135064. [PMID: 26244645 PMCID: PMC4526555 DOI: 10.1371/journal.pone.0135064] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 07/16/2015] [Indexed: 01/17/2023] Open
Abstract
MicroRNAs (miRNAs) regulate many physiological processes through post-transcriptional control of gene expression and are a major part of the small noncoding RNAs (snRNA). As hibernators can survive at low body temperatures (Tb) for many months without suffering tissue damage, understanding the mechanisms that enable them to do so are of medical interest. Because the brain integrates peripheral physiology and white adipose tissue (WAT) is the primary energy source during hibernation, we hypothesized that both of these organs play a crucial role in hibernation, and thus, their activity would be relatively increased during hibernation. We carried out the first genomic analysis of small RNAs, specifically miRNAs, in the brain and WAT of a hibernating bat (Myotis ricketti) by comparing deeply torpid with euthermic individual bats using high-throughput sequencing (Solexa) and qPCR validation of expression levels. A total of 196 miRNAs (including 77 novel bat-specific miRNAs) were identified, and of these, 49 miRNAs showed significant differences in expression during hibernation, including 33 in the brain and 25 in WAT (P≤0.01 &│logFC│≥1). Stem-loop qPCR confirmed the miRNA expression patterns identified by Solexa sequencing. Moreover, 31 miRNAs showed tissue- or state-specific expression, and six miRNAs with counts >100 were specifically expressed in the brain. Putative target gene prediction combined with KEGG pathway and GO annotation showed that many essential processes of both organs are significantly correlated with differentially expressed miRNAs during bat hibernation. This is especially evident with down-regulated miRNAs, indicating that many physiological pathways are altered during hibernation. Thus, our novel findings of miRNAs and Interspersed Elements in a hibernating bat suggest that brain and WAT are active with respect to the miRNA expression activity during hibernation.
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Affiliation(s)
- Lihong Yuan
- Guangdong Entomological Institute, Guangzhou, China
- Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangzhou, China
- Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangzhou, China
| | - Fritz Geiser
- Center for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, Australia
| | - Benfu Lin
- Animal Husbandry and Veterinary Bureau of Huadu District, Guangzhou, China
| | - Haibo Sun
- MininGene Biotechnology Co. Ltd, Beijing, China
| | - Jinping Chen
- Guangdong Entomological Institute, Guangzhou, China
- Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Guangzhou, China
- Guangdong Key Laboratory of Integrated Pest Management in Agriculture, Guangzhou, China
| | - Shuyi Zhang
- Institute of Molecular Ecology and Evolution, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
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13
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Regulation of Torpor in the Gray Mouse Lemur: Transcriptional and Translational Controls and Role of AMPK Signaling. GENOMICS PROTEOMICS & BIOINFORMATICS 2015; 13:103-10. [PMID: 26092186 PMCID: PMC4511784 DOI: 10.1016/j.gpb.2015.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/21/2015] [Indexed: 12/02/2022]
Abstract
The gray mouse lemur (Microcebus murinus) is one of few primate species that is able to enter daily torpor or prolonged hibernation in response to environmental stresses. With an emerging significance to human health research, lemurs present an optimal model for exploring molecular adaptations that regulate primate hypometabolism. A fundamental challenge is how to effectively regulate energy expensive cellular processes (e.g., transcription and translation) during transitions to/from torpor without disrupting cellular homeostasis. One such regulatory mechanism is reversible posttranslational modification of selected protein targets that offers fine cellular control without the energetic burden. This study investigates the role of phosphorylation and/or acetylation in regulating key factors involved in energy homeostasis (AMP-activated protein kinase, or AMPK, signaling pathway), mRNA translation (eukaryotic initiation factor 2α or eIF2α, eukaryotic initiation factor 4E or eIF4E, and initiation factor 4E binding protein or 4EBP), and gene transcription (histone H3) in six tissues of torpid and aroused gray mouse lemurs. Our results indicated selective tissue-specific changes of these regulatory proteins. The relative level of Thr172-phosphorylated AMPKα was significantly elevated in the heart but reduced in brown adipose tissue during daily torpor, as compared to the aroused lemurs, implicating the regulation of AMPK activity during daily torpor in these tissues. Interestingly, the levels of the phosphorylated eIFs were largely unaltered between aroused and torpid animals. Phosphorylation and acetylation of histone H3 were examined as a marker for transcriptional regulation. Compared to the aroused lemurs, level of Ser10-phosphorylated histone H3 decreased significantly in white adipose tissue during torpor, suggesting global suppression of gene transcription. However, a significant increase in acetyl-histone H3 in the heart of torpid lemurs indicated a possible stimulation of transcriptional activity of this tissue. Overall, our study demonstrates that AMPK signaling and posttranslational regulation of selected proteins may play crucial roles in the control of transcription/translation during daily torpor in mouse lemurs.
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Zhang Q, Lin Y, Zhang XY, Wang DH. Cold exposure inhibits hypothalamic Kiss-1 gene expression, serum leptin concentration, and delays reproductive development in male Brandt's vole (Lasiopodomys brandtii). INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2015; 59:679-691. [PMID: 25145442 DOI: 10.1007/s00484-014-0879-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/09/2014] [Accepted: 07/22/2014] [Indexed: 06/03/2023]
Abstract
Cold commonly affects growth and reproductive development in small mammals. Here, we test the hypothesis that low ambient temperature will affect growth and puberty onset, associated with altered hypothalamic Kiss-1 gene expression and serum leptin concentration in wild rodents. Male Brandt's voles (Lasiopodomys brandtii) were exposed to cold (4 ± 1 °C) and warm (23 ± 1 °C) conditions from the birth and sacrificed on different developmental stages (day 26, day 40, day 60, and day 90, respectively). Brandt's voles increased the thermogenic capacity of brown adipose tissue, mobilized body fat, decreased serum leptin levels, and delayed the reproductive development especially on day 40 in the cold condition. They increased food intake to compensate for the high energy demands in the cold. The hypothalamic Kiss-1 gene expression on day 26 was decreased, associated with lower wet testis mass and testis testosterone concentration on day 40, in the cold-exposed voles compared to that in the warm. Serum leptin was positively correlated with body fat, testis mass, and testosterone concentration. These data suggested that cold exposure inhibited hypothalamic Kiss-1 gene expression during the early stage of development, decreased serum leptin concentration, and delayed reproductive development in male Brandt's voles.
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Affiliation(s)
- Qiang Zhang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, 100101, Beijing, China
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Zhang L, Storey KB, Yu DN, Hu Y, Zhang JY. The complete mitochondrial genome of Ictidomys tridecemlineatus (Rodentia: Sciuridae). Mitochondrial DNA A DNA Mapp Seq Anal 2015; 27:2608-9. [PMID: 26024127 DOI: 10.3109/19401736.2015.1041117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The complete mitochondrial genome of the thirteen-lined ground squirrel, Ictidomys tridecemlineatus (Rodentia: Sciuridae) was sequenced to analyze the gene arrangement. It is a circular molecule of 16,458 bp in length including 37 genes typically found in other squirrels. The AT content of the overall base composition is 63.7% and the length of the control region is 1016 bp with 63.0% AT content. In BI and ML phylogenetic trees, I. tridecemlineatus is a sister clade to the genus Cynomys, and Tamias sibiricus is a sister clade to (Marmota himalayana + (I. tridecemlineatus + (C. leucurus + C. ludovicianus))). Ratufinae is well supported as the basal clade of Sciuridae. The monophyly of the family Sciuridae and its subfamilies Callosciurinae, Xerinae and Sciurinae are well supported.
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Affiliation(s)
- Leping Zhang
- a College of Chemistry and Life Science, Zhejiang Normal University , Jinhua , Zhejiang Province , China
| | - Kenneth B Storey
- b Department of Biology , Carleton University , Ottawa , Ontario , Canada , and
| | - Dan-Na Yu
- a College of Chemistry and Life Science, Zhejiang Normal University , Jinhua , Zhejiang Province , China .,c Institute of Ecology, Zhejiang Normal University , Jinhua , Zhejiang Province , China
| | - Yizhong Hu
- a College of Chemistry and Life Science, Zhejiang Normal University , Jinhua , Zhejiang Province , China
| | - Jia-Yong Zhang
- a College of Chemistry and Life Science, Zhejiang Normal University , Jinhua , Zhejiang Province , China .,c Institute of Ecology, Zhejiang Normal University , Jinhua , Zhejiang Province , China
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The regulation of troponins I, C and ANP by GATA4 and Nkx2-5 in heart of hibernating thirteen-lined ground squirrels, Ictidomys tridecemlineatus. PLoS One 2015; 10:e0117747. [PMID: 25679215 PMCID: PMC4334527 DOI: 10.1371/journal.pone.0117747] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 01/02/2015] [Indexed: 02/06/2023] Open
Abstract
Hibernation is an adaptive strategy used by various mammals to survive the winter under situations of low ambient temperatures and limited or no food availability. The heart of hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus) has the remarkable ability to descend to low, near 0°C temperatures without falling into cardiac arrest. We hypothesized that the transcription factors GATA4 and Nkx2-5 may play a role in cardioprotection by facilitating the expression of key downstream targets such as troponin I, troponin C, and ANP (atrial natriuretic peptide). This study measured relative changes in transcript levels, protein levels, protein post-translational modifications, and transcription factor binding over six stages: euthermic control (EC), entrance into torpor (EN), early torpor (ET), late torpor (LT), early arousal (EA), and interbout arousal (IA). We found differential regulation of GATA4 whereby transcript/protein expression, post-translational modification (phosphorylation of serine 261), and DNA binding were enhanced during the transitory phases (entrance and arousal) of hibernation. Activation of GATA4 was paired with increases in cardiac troponin I, troponin C and ANP protein levels during entrance, while increases in p-GATA4 DNA binding during early arousal was paired with decreases in troponin I and no changes in troponin C and ANP protein levels. Unlike its binding partner, the relative mRNA/protein expression and DNA binding of Nkx2-5 did not change during hibernation. This suggests that either Nkx2-5 does not play a substantial role or other regulatory mechanisms not presently studied (e.g. posttranslational modifications) are important during hibernation. The data suggest a significant role for GATA4-mediated gene transcription in the differential regulation of genes which aid cardiac-specific challenges associated with torpor-arousal.
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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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Quinones QJ, Ma Q, Zhang Z, Barnes BM, Podgoreanu MV. Organ protective mechanisms common to extremes of physiology: a window through hibernation biology. Integr Comp Biol 2014; 54:497-515. [PMID: 24848803 DOI: 10.1093/icb/icu047] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Supply and demand relationships govern survival of animals in the wild and are also key determinants of clinical outcomes in critically ill patients. Most animals' survival strategies focus on the supply side of the equation by pursuing territory and resources, but hibernators are able to anticipate declining availability of nutrients by reducing their energetic needs through the seasonal use of torpor, a reversible state of suppressed metabolic demand and decreased body temperature. Similarly, in clinical medicine the majority of therapeutic interventions to care for critically ill or trauma patients remain focused on elevating physiologic supply above critical thresholds by increasing the main determinants of delivery of oxygen to the tissues (cardiac output, perfusion pressure, hemoglobin concentrations, and oxygen saturation), as well as increasing nutritional support, maintaining euthermia, and other general supportive measures. Techniques, such as induced hypothermia and preconditioning, aimed at diminishing a patient's physiologic requirements as a short-term strategy to match reduced supply and to stabilize their condition, are few and underutilized in clinical settings. Consequently, comparative approaches to understand the mechanistic adaptations that suppress metabolic demand and alter metabolic use of fuel as well as the application of concepts gleaned from studies of hibernation, to the care of critically ill and injured patients could create novel opportunities to improve outcomes in intensive care and perioperative medicine.
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Affiliation(s)
- Quintin J Quinones
- *Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Qing Ma
- *Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Zhiquan Zhang
- *Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Brian M Barnes
- *Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Mihai V Podgoreanu
- *Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA*Department of Anesthesiology, Systems Modeling of Perioperative Organ Injury Laboratory, Duke University, Box 3094, Durham, NC 27710, USA; Institute for Arctic Biology, University of Alaska, Fairbanks, AK, USA
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Beyond retrograde and anterograde signalling: mitochondrial-nuclear interactions as a means for evolutionary adaptation and contemporary disease susceptibility. Biochem Soc Trans 2013; 41:111-7. [PMID: 23356268 DOI: 10.1042/bst20120227] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although there is general agreement that most forms of common disease develop as a consequence of a combination of factors, including genetic, environmental and behavioural contributors, the actual mechanistic basis of how these factors initiate or promote diabetes, cancer, neurodegenerative and cardiovascular diseases in some individuals but not in others with seemingly identical risk factor profiles, is not clearly understood. In this respect, consideration of the potential role for mitochondrial genetics, damage and function in influencing common disease susceptibility seems merited, given that the prehistoric challenges were the original factors that moulded cellular function, and these were based upon the mitochondrial-nuclear relationships that were established during evolutionary history. These interactions were probably refined during prehistoric environmental selection events that, at present, are largely absent. Contemporary risk factors such as diet, sedentary lifestyle and increased longevity, which influence our susceptibility to a variety of chronic diseases were not part of the dynamics that defined the processes of mitochondrial-nuclear interaction, and thus cell function. Consequently, the prehistoric challenges that contributed to cell functionality and evolution should be considered when interpreting and designing experimental data and strategies. Although several molecular epidemiological studies have generally supported this notion, studies that probe beyond these associations are required. Such investigation will mark the initial steps for mechanistically addressing the provocative concept that contemporary human disease susceptibility is the result of prehistoric selection events for mitochondrial-nuclear function, which increased the probability for survival and reproductive success during evolution.
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Rouble AN, Hefler J, Mamady H, Storey KB, Tessier SN. Anti-apoptotic signaling as a cytoprotective mechanism in mammalian hibernation. PeerJ 2013; 1:e29. [PMID: 23638364 PMCID: PMC3628845 DOI: 10.7717/peerj.29] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 01/11/2013] [Indexed: 12/20/2022] Open
Abstract
In the context of normal cell turnover, apoptosis is a natural phenomenon involved in making essential life and death decisions. Apoptotic pathways balance signals which promote cell death (pro-apoptotic pathways) or counteract these signals (anti-apoptotic pathways). We proposed that changes in anti-apoptotic proteins would occur during mammalian hibernation to aid cell preservation during prolonged torpor under cellular conditions that are highly injurious to most mammals (e.g. low body temperatures, ischemia). Immunoblotting was used to analyze the expression of proteins associated with pro-survival in six tissues of thirteen-lined ground squirrels, Ictidomys tridecemlineatus. The brain showed a concerted response to torpor with significant increases in the levels of all anti-apoptotic targets analyzed (Bcl-2, Bcl-xL, BI-1, Mcl-1, cIAP1/2, xIAP) as well as enhanced phosphorylation of Bcl-2 at S70 and T56. Heart responded similarly with most anti-apoptotic proteins elevated significantly during torpor except for Bcl-xL and xIAP that decreased and Mcl-1 that was unaltered. In liver, BI-1 increased whereas cIAP1/2 decreased. In kidney, there was an increase in BI-1, cIAP and xIAP but decreases in Bcl-xL and p-Bcl-2(T56) content. In brown adipose tissue, protein levels of BI-1, cIAP1/2, and xIAP decreased significantly during torpor (compared with euthermia) whereas Bcl-2, Bcl-xL, Mcl-1 were unaltered; however, Bcl-2 showed enhanced phosphorylation at Thr56 but not at Ser70. In skeletal muscle, only xIAP levels changed significantly during torpor (an increase). The data show that anti-apoptotic pathways have organ-specific responses in hibernators with a prominent potential role in heart and brain where coordinated enhancement of anti-apoptotic proteins occurred in response to torpor.
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Affiliation(s)
- Andrew N Rouble
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Joshua Hefler
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Hapsatou Mamady
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
| | - Shannon N Tessier
- Institute of Biochemistry & Department of Biology, Carleton University, Ottawa, Ontario, Canada K1S 5B6
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Wu CW, Biggar KK, Storey KB. Biochemical adaptations of mammalian hibernation: exploring squirrels as a perspective model for naturally induced reversible insulin resistance. ACTA ACUST UNITED AC 2013; 46:1-13. [PMID: 23314346 PMCID: PMC3854349 DOI: 10.1590/1414-431x20122388] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/17/2012] [Indexed: 01/20/2023]
Abstract
An important disease among human metabolic disorders is type 2 diabetes mellitus. This disorder involves multiple physiological defects that result from high blood glucose content and eventually lead to the onset of insulin resistance. The combination of insulin resistance, increased glucose production, and decreased insulin secretion creates a diabetic metabolic environment that leads to a lifetime of management. Appropriate models are critical for the success of research. As such, a unique model providing insight into the mechanisms of reversible insulin resistance is mammalian hibernation. Hibernators, such as ground squirrels and bats, are excellent examples of animals exhibiting reversible insulin resistance, for which a rapid increase in body weight is required prior to entry into dormancy. Hibernator studies have shown differential regulation of specific molecular pathways involved in reversible resistance to insulin. The present review focuses on this growing area of research and the molecular mechanisms that regulate glucose homeostasis, and explores the roles of the Akt signaling pathway during hibernation. Here, we propose a link between hibernation, a well-documented response to periods of environmental stress, and reversible insulin resistance, potentially facilitated by key alterations in the Akt signaling network, PPAR-γ/PGC-1α regulation, and non-coding RNA expression. Coincidentally, many of the same pathways are frequently found to be dysregulated during insulin resistance in human type 2 diabetes. Hence, the molecular networks that may regulate reversible insulin resistance in hibernating mammals represent a novel approach by providing insight into medical treatment of insulin resistance in humans.
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Affiliation(s)
- C-W Wu
- Department of Biology, Institute of Biochemistry, Carleton University, Ottawa, ON, Canada
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Wu CW, Storey KB. Regulation of the mTOR signaling network in hibernating thirteen-lined ground squirrels. J Exp Biol 2012; 215:1720-7. [DOI: 10.1242/jeb.066225] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
SUMMARY
For many small mammals, survival over the winter months is a serious challenge because of low environmental temperatures and limited food availability. The solution for many species, such as thirteen-lined ground squirrels (Ictidomys tridecemlineatus), is hibernation, an altered physiological state characterized by seasonal heterothermy and entry into long periods of torpor that are interspersed with short arousals back to euthermia. During torpor, metabolic rate is strongly reduced to achieve major energy savings, and a coordinated depression of non-essential ATP-expensive functions such as protein synthesis takes place. This study examines the mammalian target of rapamycin (mTOR) signaling pathway, a crucial component of the insulin receptor network, over six stages of the torpor–arousal cycle of hibernation. Immunoblots showed that the phosphorylation state of mTORSer2448 was strongly reduced in skeletal muscle (by 55%) during late torpor but increased by 200% during early arousal compared with euthermia. However, the phosphorylation state of this residue remained relatively constant in cardiac muscle during torpor but was enhanced during entrance into torpor and early arousal from torpor stages (by 2.9- and 3.2-fold, respectively). Phosphorylation states of upstream regulators of mTOR, p-AktThr473 and p-TSC2Thr1462, were also suppressed in skeletal muscle by 55 and 51%, respectively, during late torpor, as were selected downstream substrates – p-4E-BP1Thr46 and p-S6Ser235 contents dropped by 74 and 41%, respectively. Overall, the results indicate suppressed mTOR signaling in skeletal muscle, but not cardiac muscle, during torpor. By contrast, activation of mTOR and other components of the mTORC1 complex (p-PRAS40Thr246 and GβL) occurred during early arousal in both skeletal and cardiac muscle.
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Affiliation(s)
- Cheng-Wei Wu
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, CanadaK1S 5B6
| | - Kenneth B. Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, CanadaK1S 5B6
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Tessier SN, Storey KB. Myocyte enhancer factor-2 and cardiac muscle gene expression during hibernation in thirteen-lined ground squirrels. Gene 2012; 501:8-16. [PMID: 22513076 DOI: 10.1016/j.gene.2012.04.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/19/2012] [Accepted: 04/04/2012] [Indexed: 12/01/2022]
Abstract
Many small mammals turn to hibernation to survive the winter, cycling through bouts of prolonged torpor where metabolic rate and body temperature fall to low levels. Remarkably, hypertrophy is promoted in cardiac muscle to support the stronger contractions needed in the cold. We proposed that altered expression of mRNA/protein levels of myocyte enhancer factor-2 (MEF2A, MEF2C) transcription factors and downstream targets (e.g., desmin, glucose transporter 4, and myomesin 1) would aid cardiac muscle of thirteen-lined ground squirrels (Ictidomys tridecemlineatus) in meeting challenges associated with hibernation. Gene and protein responses were compared over six conditions: control (euthermic animals in a 5 °C cold room), entrance into torpor, short and long torpors, arousal and interbout. Mef2a relative transcript levels were significantly elevated from controls contributing to increases in MEF2A protein levels throughout the torpor-arousal bout. In addition, levels of phosphorylated, activated MEF2A (Thr312) correlated with increases in MEF2A-DNA binding. MEF2C transcript/protein levels were significantly elevated over controls at selected sampling points whereas phosphorylated/activated MEF2C (Ser387) levels rose during torpor and DNA binding was most prominent during entrance into torpor. Some gene targets of MEF2 action were also upregulated. Desmin transcript levels remained constant whereas enhanced protein expression occurred during entrance into torpor. Glut4 transcript levels were enhanced in arousal and protein expression was elevated over all five sampling points during torpor/arousal. Myomesin 1 transcript levels increased between early torpor and early arousal and protein levels increased during entrance and deep torpor. These data provide insights into the changes in gene/protein in expression that help to prepare cardiac muscle for hibernation.
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Affiliation(s)
- Shannon N Tessier
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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Krzywanski DM, Moellering DR, Fetterman JL, Dunham-Snary KJ, Sammy MJ, Ballinger SW. The mitochondrial paradigm for cardiovascular disease susceptibility and cellular function: a complementary concept to Mendelian genetics. J Transl Med 2011; 91:1122-35. [PMID: 21647091 PMCID: PMC3654682 DOI: 10.1038/labinvest.2011.95] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
While there is general agreement that cardiovascular disease (CVD) development is influenced by a combination of genetic, environmental, and behavioral contributors, the actual mechanistic basis of how these factors initiate or promote CVD development in some individuals while others with identical risk profiles do not, is not clearly understood. This review considers the potential role for mitochondrial genetics and function in determining CVD susceptibility from the standpoint that the original features that molded cellular function were based upon mitochondrial-nuclear relationships established millions of years ago and were likely refined during prehistoric environmental selection events that today, are largely absent. Consequently, contemporary risk factors that influence our susceptibility to a variety of age-related diseases, including CVD were probably not part of the dynamics that defined the processes of mitochondrial-nuclear interaction, and thus, cell function. In this regard, the selective conditions that contributed to cellular functionality and evolution should be given more consideration when interpreting and designing experimental data and strategies. Finally, future studies that probe beyond epidemiologic associations are required. These studies will serve as the initial steps for addressing the provocative concept that contemporary human disease susceptibility is the result of selection events for mitochondrial function that increased chances for prehistoric human survival and reproductive success.
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Affiliation(s)
- David M Krzywanski
- Division of Molecular and Cellular Pathology, Department of Pathology, The University of Alabama at Birmingham, Birmingham, AL, USA
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Nowell MM, Choi H, Rourke BC. Muscle plasticity in hibernating ground squirrels (Spermophilus lateralis) is induced by seasonal, but not low-temperature, mechanisms. J Comp Physiol B 2010; 181:147-64. [DOI: 10.1007/s00360-010-0505-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 07/05/2010] [Accepted: 07/23/2010] [Indexed: 12/17/2022]
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Expression of myocyte enhancer factor-2 and downstream genes in ground squirrel skeletal muscle during hibernation. Mol Cell Biochem 2010; 344:151-62. [PMID: 20617369 DOI: 10.1007/s11010-010-0538-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 06/24/2010] [Indexed: 01/03/2023]
Abstract
Myocyte enhancer factor-2 (MEF2) transcription factors regulate the expression of a variety of genes encoding contractile proteins and other proteins associated with muscle performance. We proposed that changes in MEF2 levels and expression of selected downstream targets would aid the skeletal muscle of thirteen-lined ground squirrels (Spermophilus tridecemlineatus) in meeting metabolic challenges associated with winter hibernation; e.g., cycles of torpor-arousal, body temperature that can fall to near 0°C, long periods of inactivity that could lead to atrophy. MEF2A protein levels were significantly elevated when animals were in torpor (maximally 2.8-fold higher than in active squirrels) and the amount of phosphorylated active MEF2A Thr312 increased during entrance into torpor. MEF2C levels also rose significantly during entrance and torpor as did the amount of phosphorylated MEF2C Ser387. Furthermore, both MEF2 members showed elevated amounts in the nuclear fraction during torpor as well as enhanced binding to DNA indicating that MEF2-mediated gene expression was up-regulated in torpid animals. Indeed, the protein products of two MEF2 downstream gene targets increased in muscle during torpor (glucose transporter isoforms 4; GLUT4) or early arousal (myogenic differentiation; MyoD). Significant increases in Glut4 and MyoD mRNA transcript levels correlated with the rise in protein product levels and provided further support for the activation of MEF2-mediated gene expression in the hibernator. Transcript levels of Mef2a and Mef2c also showed time-dependent patterns with levels of both being highest during arousal from torpor. The data suggest a significant role for MEF2-mediated gene transcription in the selective adjustment of muscle protein complement over the course of torpor-arousal cycles.
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Storey KB, Heldmaier G, Rider MH. Mammalian Hibernation: Physiology, Cell Signaling, and Gene Controls on Metabolic Rate Depression. DORMANCY AND RESISTANCE IN HARSH ENVIRONMENTS 2010. [DOI: 10.1007/978-3-642-12422-8_13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Malatesta M, Perdoni F, Battistelli S, Muller S, Zancanaro C. The cell nuclei of skeletal muscle cells are transcriptionally active in hibernating edible dormice. BMC Cell Biol 2009; 10:19. [PMID: 19284674 PMCID: PMC2663540 DOI: 10.1186/1471-2121-10-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 03/14/2009] [Indexed: 12/18/2022] Open
Abstract
Background Skeletal muscle is able to react in a rapid, dynamic way to metabolic and mechanical stimuli. In particular, exposure to either prolonged starvation or disuse results in muscle atrophy. At variance, in hibernating animals muscle atrophy may be scarce or absent after bouts of hibernation i.e., periods of prolonged (months) inactivity and food deprivation, and muscle function is fully preserved at arousal. In this study, myocytes from the quadriceps muscle of euthermic and hibernating edible dormice were investigated by a combination of morphological, morphometrical and immunocytochemical analyses at the light and electron microscopy level. The focus was on cell nuclei and mitochondria, which are highly sensitive markers of changing metabolic rate. Results Findings presented herein demonstrate that: 1) the general histology of the muscle, inclusive of muscle fibre shape and size, and the ratio of fast and slow fibre types are not affected by hibernation; 2) the fine structure of cytoplasmic and nuclear constituents is similar in euthermia and hibernation but for lipid droplets, which accumulate during lethargy; 3) during hibernation, mitochondria are larger in size with longer cristae, and 4) myonuclei maintain the same amount and distribution of transcripts and transcription factors as in euthermia. Conclusion In this study we demonstrate that skeletal muscle cells of the hibernating edible dormouse maintain their structural and functional integrity in full, even after months in the nest. A twofold explanation for that is envisaged: 1) the maintenance, during hibernation, of low-rate nuclear and mitochondrial activity counterbalancing myofibre wasting, 2) the intensive muscle stimulation (shivering) during periodic arousals in the nest, which would mimic physical exercise. These two factors would prevent muscle atrophy usually occurring in mammals after prolonged starvation and/or inactivity as a consequence of prevailing catabolism. Understanding the mechanisms responsible for skeletal muscle preservation in hibernators could pave the way to prevention and treatment of muscle wasting associated with pathological conditions or ageing as well as life in extreme environments, such as ocean deeps or spaceflights.
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Affiliation(s)
- Manuela Malatesta
- Dipartimento di Scienze Morfologico-Biomediche, Sezione di Anatomia e Istologia, University of Verona, Italy.
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Icardo JM, Amelio D, Garofalo F, Colvee E, Cerra MC, Wong WP, Tota B, Ip YK. The structural characteristics of the heart ventricle of the African lungfish Protopterus dolloi: freshwater and aestivation. J Anat 2008; 213:106-19. [PMID: 18482286 PMCID: PMC2526117 DOI: 10.1111/j.1469-7580.2008.00901.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2008] [Indexed: 11/27/2022] Open
Abstract
This paper reports on the structure and ultrastructure of the ventricular myocardium of the African lungfish Protopterus dolloi in freshwater (FW), in aestivation (AE), and after the AE period. The myocardium shows a conventional myofibrillar structure. All the myocytes contain large intracytoplasmic spaces occupied by a pale material that could contain glycosaminoglycans and/or glycogen, which may be used as food and water reservoirs. In FW, the myocytes in the trabeculae associated with the free ventricular wall show structural signs of low transcriptional and metabolic activity (heterochromatin, mitochondria of the dense type). These signs are partially reversed during the AE period (euchromatin, mitochondria with a light matrix), with a return to the FW appearance after arousal. The myocytes in the septum show, in FW conditions, nuclear polymorphism (heterochromatin, euchromatin), and two types (colliquative and coagulative) of necrosis. In AE, all the septal myocytes show euchromatin, and the number of necrotic cells increases greatly. Cell necrosis appears to be related to the septal architecture. After arousal, the septal myocytes exhibit a heterochromatin pattern, the number of necrotic cells decreases, cell debris accumulates under the endocardium, and phagocytosis takes place. Despite being a morphologic continuum, the trabeculae associated with the free ventricular wall appear to constitute a different compartment from that formed by the trabeculae in the ventricular septum. Paradoxically, AE appears to trigger an increase in transcriptional and synthetic myocardial activities, especially at the level of the ventricular septum. This activity may be involved in mechanisms of autocrine/paracrine regulation. Aestivation cannot be regarded as the result of a general depression of all cellular and organic activities. Rather, it is a much more complex state in which the interplay between upregulation and downregulation of diverse cell activities appears to play a fundamental role.
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Affiliation(s)
- José M Icardo
- Department of Anatomy and Cell Biology, University of Cantabria, Santander, Spain.
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Mitochondrial metabolism in hibernation and daily torpor: a review. J Comp Physiol B 2008; 178:811-27. [PMID: 18551297 DOI: 10.1007/s00360-008-0282-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Revised: 05/15/2008] [Accepted: 05/26/2008] [Indexed: 01/20/2023]
Abstract
Hibernation and daily torpor involve substantial decreases in body temperature and metabolic rate, allowing birds and mammals to cope with cold environments and/or limited food. Regulated suppression of mitochondrial metabolism probably contributes to energy savings: state 3 (phosphorylating) respiration is lower in liver mitochondria isolated from mammals in hibernation or daily torpor compared to normothermic controls, although data on state 4 (non-phosphorylating) respiration are equivocal. However, no suppression is seen in skeletal muscle, and there is little reliable data from other tissues. In both daily torpor and hibernation, liver state 3 substrate oxidation is suppressed, especially upstream of electron transport chain complex IV. In hibernation respiratory suppression is reversed quickly in arousal even when body temperature is very low, implying acute regulatory mechanisms, such as oxaloacetate inhibition of succinate dehydrogenase. Respiratory suppression depends on in vitro assay temperature (no suppression is evident below approximately 30 degrees C) and (at least in hibernation) dietary polyunsaturated fats, suggesting effects on inner mitochondrial membrane phospholipids. Proton leakiness of the inner mitochondrial membrane does not change in hibernation, but this also depends on dietary polyunsaturates. In contrast proton leak increases in daily torpor, perhaps limiting reactive oxygen species production.
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Yan J, Barnes BM, Kohl F, Marr TG. Modulation of gene expression in hibernating arctic ground squirrels. Physiol Genomics 2008; 32:170-81. [DOI: 10.1152/physiolgenomics.00075.2007] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We performed a broadscale screening of differential gene expression using both high-throughput bead-array technology and real-time PCR assay in brown adipose tissue, liver, heart, hypothalamus, and skeletal muscle in hibernating arctic ground squirrels, comparing animals sampled after two durations of steady-state torpor, during two stages of spontaneous arousal episodes, and in animals after they ended hibernation. Significant seasonal and torpor-arousal cycle differences of gene expression were detected in genes involved in glycolysis, fatty acid metabolism, gluconeogenesis, amino acid metabolism, molecular transport, detoxification, cardiac contractility, circadian rhythm, cell growth and apoptosis, muscle dystrophy, and RNA and protein protection. We observed, for the first time, complex modulation of gene expression during multiple stages of torpor-arousal cycles. The mRNA levels of certain metabolic genes drop significantly during the transition from late torpor to early arousal, perhaps due to the rapid turnover of mRNA transcripts resulting from the translational demands during thermogenesis in early arousal, whereas the mRNA levels of genes related to circadian rhythm, cell growth, and apoptosis rise significantly in the early or late arousal phases during torpor-arousal cycle, suggesting the resumption of circadian rhythm and cell cycle during arousal.
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Affiliation(s)
- Jun Yan
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska
- CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes of Biological Sciences, Shanghai, China
| | - Brian M. Barnes
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska
| | - Franziska Kohl
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska
| | - Thomas G. Marr
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska
- Hiberna Corporation, Boulder, Colorado
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Yoo W, Lee K, Gwag T, Ju H, Yamashita M, Choi I. Seasonal proteomic plasticity in the brain of a mammalian hibernator. ACTA ACUST UNITED AC 2008. [DOI: 10.2187/bss.22.99] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Lee K, Park JY, Yoo W, Gwag T, Lee JW, Byun MW, Choi I. Overcoming muscle atrophy in a hibernating mammal despite prolonged disuse in dormancy: Proteomic and molecular assessment. J Cell Biochem 2008; 104:642-56. [DOI: 10.1002/jcb.21653] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
The use of DNA microarrays has gained wider acceptance as a standard tool for molecular biology studies over the past decade. In particular, biomedical studies embraced this technology as soon as arrays were produced for the common laboratory species. Slower to develop, however, has been the use of microarray screening with non-standard animal models, even though these species present fascinating physiological phenomena for study. The very high cost and huge amount of work involved in developing and producing a DNA array or microarray for a new species is prohibitive for most researchers working in comparative biology. The alternative is to explore the use of heterologous array hybridization, screening for stress-induced gene expression in one species using an array developed for another species. This chapter provides a comprehensive review of the current literature on heterologous DNA array hybridization and explores the factors that must be taken into account when performing heterologous microarray analysis on nonstandard species. Changes in methodology (e.g. hybridization conditions, stringency of washing) to optimize the percent cross reaction, the potential for false positives and false negatives to occur, and techniques for downstream analysis and confirmation of array data are all discussed. Examples of cross-hybridization using human microarrays are discussed using phylogenetically diverse species ranging from ground squirrels to frogs to snails. As with any new technology, the willingness to grasp cross-species analysis has been slow but the future looks bright for heterologous DNA hybridization and microarray analysis now that the initial hurdles have been overcome.
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Yuan L, Chen J, Lin B, Zhang J, Zhang S. Differential expression and functional constraint of PRL-2 in hibernating bat. Comp Biochem Physiol B Biochem Mol Biol 2007; 148:375-81. [PMID: 17683965 DOI: 10.1016/j.cbpb.2007.07.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 07/07/2007] [Accepted: 07/07/2007] [Indexed: 11/21/2022]
Abstract
Circannual hibernation is a biological adaptation to periods of cold and food shortage and the role of the brain in its control is poorly understood. An SSH library of hibernating bat brains (Rhinolophus ferrumequinum) was constructed in order to explore the molecular mechanism of hibernation. An up-regulated gene, PRL-2, was obtained from hibernating bat brains. PRL-2 is a member of PTP family and has an important function in controlling cell growth. Alignment of sequences showed that PRL-2 is highly conserved among species, including two species of hibernating bats (R. ferrumequinum and Myotis ricketti). Moreover, Maximum Likelihood Analysis suggested that it may experience strong selection pressure leading to functional constraint in evolution, which indicated the significance of PRL-2 in normal bio-function. RQ-PCR was performed and statistical analysis suggested that PRL-2 exhibited distinct differential expression patterns in different organs during hibernation. In heart, fat and brain tissue of hibernating bats, the transcriptional level of PRL-2 increased almost 170%, 35% and 12% respectively. However, in muscle it decreased nearly 70%. The change of mRNA level of PRL-2 in heart tissue of hibernating bats was significantly higher than that in heart tissue of active controls (P=0.043). However, the regulation mechanism of differential expression of PRL-2 and the signal pathway involved are still unknown.
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Affiliation(s)
- Lihong Yuan
- School of Life Science, East China Normal University, Shanghai 200062, China
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Chen J, Yuan L, Sun M, Zhang L, Zhang S. Screening of hibernation-related genes in the brain of Rhinolophus ferrumequinum during hibernation. Comp Biochem Physiol B Biochem Mol Biol 2007; 149:388-93. [PMID: 18055242 DOI: 10.1016/j.cbpb.2007.10.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 01/17/2023]
Abstract
The greater horseshoe bat (Rhinolophus ferrumequinum) is a widely distributed small mammal that hibernates annually. A systematic study was initiated to identify differentially expressed genes in hibernating and aroused states of the greater horseshoe bat brain by using suppressed subtractive hybridization technique and dot blot. Forty-one over-expressed ESTs in the hibernating state were found and 17 were known genes reported in NCBI. Among these 17 genes, three were further checked by real time PCR. The bioinformatics analysis suggests that the major over-expressed ESTs may be responsible for the regulation of cell cycle and apoptosis, the growth of neurons, signal transduction and neuroprotection, gene expression regulation, and intracellular trafficking.
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Affiliation(s)
- Jinping Chen
- South China Institute of Endangered Animals, Guangzhou, 510260, China
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38
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Crawford FIJ, Hodgkinson CL, Ivanova E, Logunova LB, Evans GJ, Steinlechner S, Loudon ASI. Influence of torpor on cardiac expression of genes involved in the circadian clock and protein turnover in the Siberian hamster (Phodopus sungorus). Physiol Genomics 2007; 31:521-30. [PMID: 17848604 DOI: 10.1152/physiolgenomics.00131.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Siberian hamster exhibits the key winter adaptive strategy of daily torpor, during which metabolism and heart rate are slowed for a few hours and body temperature declines by up to 20 degrees C, allowing substantial energetic savings. Previous studies of hibernators in which temperature drops by >30 degrees C for many days to weeks have revealed decreased transcription and translation during hypometabolism and identified several key physiological pathways involved. Here we used a cDNA microarray to define cardiac transcript changes over the course of a daily torpor bout and return to normothermia, and we show that, in common with hibernators, a relatively small proportion of the transcriptome (<5%) exhibited altered expression over a torpor bout. Pathways exhibiting significantly altered gene expression included transcriptional regulation, RNA stability and translational control, globin regulation, and cardiomyocyte function. Remarkably, gene representatives of the entire ubiquitylation pathway were significantly altered over the torpor bout, implying a key role for cardiac protein turnover and translation during a low-temperature torpor bout. The circadian clock maintained rhythmic transcription during torpor. Quantitative PCR profiling of heart, liver, and lung and in situ hybridization studies of clock genes in the hypothalamic circadian clock in the suprachiasmatic nucleus revealed that many circadian regulated transcripts exhibited synchronous alteration in expression during arousal. Our data highlight the potential importance of genes involved in protein turnover as part of the adaptive strategy of low-temperature torpor in a seasonal mammal.
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Eddy SF, Morin P, Storey KB. Differential expression of selected mitochondrial genes in hibernating little brown bats,Myotis lucifugus. ACTA ACUST UNITED AC 2006; 305:620-30. [PMID: 16721807 DOI: 10.1002/jez.a.294] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
High rates of non-shivering thermogenesis by brown adipose tissue accompanied by additional shivering thermogenesis in skeletal muscle provide the powerful reheating of body organs that allows hibernating mammals to return from their state of cold torpor back to euthermic function. Previous studies have suggested that changes to brown adipose mitochondria occur during hibernation and are partially responsible for its capacity for non-shivering thermogenesis. The current study shows that selected mitochondrial enzyme activities are elevated and selected genes and proteins are induced during torpor in brown adipose tissue of the little brown bat, Myotis lucifugus. Cytochrome oxidase activity in brown adipose tissue was more than 3-fold higher during torpor than in euthermic animals. Transcript levels of mitochondria-encoded genes, coxII and nad4, were also 3-4-fold higher during torpor, as evidenced by northern blotting. By contrast, transcripts of these genes were unchanged in skeletal muscle during torpor. Protein levels of carnitine palmitoyl transferase-1beta, an enzyme embedded in the outer membrane of the mitochondria that is the rate-limiting step enzyme in beta-oxidation, were also elevated by 2-fold during torpor in brown adipose but were unchanged in skeletal muscle. Cloning and sequencing of a 624 bp segment of cpt-1beta revealed a number of amino acid substitutions in the bat protein as compared to CPT-1beta from other mammals; these may be beneficial for enzyme function at low body temperatures during torpor. This study provides further evidence for a key role of mitochondria in hibernation.
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Affiliation(s)
- Sean F Eddy
- Institute of Biochemistry and Department of Chemistry Carleton University, Ottawa, Ont., Canada K1S 5B6.
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40
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Hudson NJ, Lehnert SA, Ingham AB, Symonds B, Franklin CE, Harper GS. Lessons from an estivating frog: sparing muscle protein despite starvation and disuse. Am J Physiol Regul Integr Comp Physiol 2006; 290:R836-43. [PMID: 16239372 DOI: 10.1152/ajpregu.00380.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long (6- to 9-mo) bouts of estivation in green-striped burrowing frogs lead to 28% atrophy of cruralis oxidative fibers ( P < 0.05) and some impairment of in vitro gastrocnemius endurance ( P < 0.05) but no significant deficit in maximal twitch force production. These data suggest the preferential atrophy of oxidative fibers at a rate slower than, but comparable to, laboratory disuse models. We tested the hypothesis that the frog limits atrophy by modulating oxidative stress. We assayed various proteins at the transcript level and verified these results for antioxidant enzymes at the biochemical level. Transcript data for NADH ubiquinone oxidoreductase subunit 1 (71% downregulated, P < 0.05) and ATP synthase (67% downregulated, P < 0.05) are consistent with mitochondrial quiescence and reduced oxidant production. Meanwhile, uncoupling protein type 2 transcription ( P = 0.31), which is thought to reduce mitochondrial leakage of reactive oxygen species, was maintained. Total antioxidant defense of water-soluble (22.3 ± 1.7 and 23.8 ± 1.5 μM/μg total protein in control and estivator, respectively, P = 0.53) and membrane-bound proteins (31.5 ± 1.9 and 42.1 ± 7.3 μM/μg total protein in control and estivator, respectively, P = 0.18) was maintained, equivalent to a bolstering of defense relative to oxygen insult. This probably decelerates muscle atrophy by preventing accumulation of oxidative damage in static protein reserves. Transcripts of the mitochondrially encoded antioxidant superoxide dismutase type 2 (67% downregulated, P < 0.05) paralleled mitochondrial activity, whereas nuclear-encoded catalase and glutathione peroxidase were maintained at control values ( P = 0.42 and P = 0.231), suggesting a dissonance between mitochondrial and nuclear antioxidant expression. Pyruvate dehydrogenase kinase 4 transcription was fourfold lower in estivators ( P = 0.11), implying that, in contrast to mammalian hibernators, this enzyme does not drive the combustion of lipids that helps spare hypometabolic muscle.
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Affiliation(s)
- Nicholas J Hudson
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, 306 Carmody Rd., St. Lucia, Brisbane, Queensland 4072, Australia.
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Yan J, Burman A, Nichols C, Alila L, Showe LC, Showe MK, Boyer BB, Barnes BM, Marr TG. Detection of differential gene expression in brown adipose tissue of hibernating arctic ground squirrels with mouse microarrays. Physiol Genomics 2006; 25:346-53. [PMID: 16464973 DOI: 10.1152/physiolgenomics.00260.2005] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hibernation is an energy-saving strategy adopted by a wide range of mammals to survive highly seasonal or unpredictable environments. Arctic ground squirrels living in Alaska provide an extreme example, with 6- to 9-mo-long hibernation seasons when body temperature alternates between levels near 0 degrees C during torpor and 37 degrees C during arousal episodes. Heat production during hibernation is provided, in part, by nonshivering thermogenesis that occurs in large deposits of brown adipose tissue (BAT). BAT is active at tissue temperatures from 0 to 37 degrees C during rewarming and continuously at near 0 degrees C during torpor in subfreezing conditions. Despite its crucial role in hibernation, the global gene expression patterns in BAT during hibernation compared with the nonhibernation season remain largely unknown. We report a large-scale study of differential gene expression in BAT between winter hibernating and summer active arctic ground squirrels using mouse microarrays. Selected differentially expressed genes identified on the arrays were validated by quantitative real-time PCR using ground squirrel specific primers. Our results show that the mRNA levels of the genes involved in nearly every step of the biochemical pathway leading to nonshivering thermogenesis are significantly increased in BAT during hibernation, whereas those of genes involved in protein biosynthesis are significantly decreased compared with summer active animals in August. Surprisingly, the differentially expressed genes also include adipocyte differentiation-related protein or adipophilin (Adfp), gap junction protein 1 (Gja1), and secreted protein acidic and cysteine-rich (Sparc), which may play a role in enhancing thermogenesis at low tissue temperatures in BAT.
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Affiliation(s)
- Jun Yan
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA.
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Abstract
New technologies in genomics and proteomics are revolutionizing the study of adaptation to environmental stress. These approaches provide a comprehensive overview of the responses of thousands of genes/proteins to stress and enormously expand our view of the molecular and metabolic changes that underlie physiological responses. Several new technologies can help physiological labs to become gene hunters. DNA array screening is particularly effective for two purposes: (1) identifying coordinated responses by functional groups of gene/proteins such as multiple members of a signal transduction cascade or enzymes of a metabolic pathway, and (2) highlighting cell functions that have never before been linked with the stress under consideration. We have shown that heterologous screening of DNA arrays can be a highly effective method of gene hunting for the comparative biochemist provided that it is followed up by species-specific analyses including PCR to quantify transcript levels and Western blotting to analyze protein responses. Recent work in my lab has used cDNA array screening to evaluate responses to low oxygen by multiple hypoxia/anoxia tolerant systems, revealing common gene responses across phylogeny. Analysis of vertebrate facultative anaerobiosis in freshwater turtles reveals an interesting mixture of gene responses, including up-regulation of antioxidant enzymes, protease inhibitors, and proteins of iron metabolism; a few of these are coordinated by the hypoxia inducible factor in other systems but most are not. Array screening is also providing new insights into how exercise stimulates the growth of differentiated muscle cells and studies in our lab are identifying the gene responses associated with "anti-exercise"--gene up-regulation that aids hibernating mammals to maintain their muscle mass despite months of inactivity.
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Affiliation(s)
- Kenneth B Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada.
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Brauch KM, Dhruv ND, Hanse EA, Andrews MT. Digital transcriptome analysis indicates adaptive mechanisms in the heart of a hibernating mammal. Physiol Genomics 2005; 23:227-34. [PMID: 16076930 DOI: 10.1152/physiolgenomics.00076.2005] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Survival of near-freezing body temperatures and reduced blood flow during hibernation is likely the result of changes in the expression of specific genes. In this study, we described a comprehensive survey of mRNAs in the heart of the thirteen-lined ground squirrel ( Spermophilus tridecemlineatus) before and during hibernation. The heart was chosen for this study because it is a contractile organ that must continue to work despite body temperatures of 5°C and the lack of food for periods of 5–6 mo. We used a digital gene expression assay involving high-throughput sequencing of directional cDNA libraries from hearts of active and hibernating ground squirrels to determine the identity and frequency of 3,532 expressed sequence tags (ESTs). Statistical analysis of the active and hibernating heart expression profile indicated the differential regulation of 48 genes based on a P ≤ 0.03 threshold. Several of the differentially expressed genes identified in this screen encode proteins that likely account for uninterrupted cardiac function during hibernation, including those involved in metabolism, contractility, Ca2+handling, and low-temperature catalysis. A sampling of genes showing higher expression during hibernation includes phosphofructokinase, pancreatic triacylglycerol lipase, pyruvate dehydrogenase kinase 4 (PDK4), aldolase A, sarco(endo)plasmic reticulum Ca2+-ATPase 2a (SERCA2a), titin, and four-and-a-half LIM domains protein 2 (FHL2). Genes showing reduced levels of expression during hibernation include cyclin-dependent kinase 2-associated protein 1 (CDK2AP1), troponin C, phospholamban, Ca2+/calmodulin-dependent protein kinase II (CaMKII), calmodulin, and four subunits of cytochrome c oxidase.
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Eddy SF, McNally JD, Storey KB. Up-regulation of a thioredoxin peroxidase-like protein, proliferation-associated gene, in hibernating bats. Arch Biochem Biophys 2005; 435:103-11. [PMID: 15680912 DOI: 10.1016/j.abb.2004.11.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 11/17/2004] [Indexed: 12/20/2022]
Abstract
Two-dimensional gel electrophoresis was used to assess differential protein expression between euthermic and hibernating states in heart of Myotis lucifugus. A hibernation-induced protein was identified by mass spectrometry as a thioredoxin peroxidase-like protein known as PAG. Western blotting confirmed up-regulation (>2-fold) and RT-PCR also revealed up-regulation (>5-fold) of pag mRNA. Cloning revealed a highly conserved sequence suggesting a conserved function for PAG. Oxidative stress markers, p-IkappaB-alpha (Ser 32) and p-HSP27 (Ser 78/82), were also up-regulated in heart and skeletal muscle during hibernation. Although there are selected increases in gene/protein expression during hibernation, general translation inhibition occurs as part of metabolic rate depression. This was confirmed by elevated levels of the inactive forms of the eIF2alpha (Ser 51) in both heart and skeletal muscle (2- to 5-fold higher than in euthermia) and the eEF2 (Thr 51) in skeletal muscle (a 15-fold increase). This study suggests that hibernators may use up-regulation of specific proteins to counteract oxidative stress.
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Affiliation(s)
- Sean F Eddy
- Departments of Chemistry and Biology, Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
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MacDonald JA, Storey KB. Mitogen-activated protein kinases and selected downstream targets display organ-specific responses in the hibernating ground squirrel. Int J Biochem Cell Biol 2005; 37:679-91. [PMID: 15618024 DOI: 10.1016/j.biocel.2004.05.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 05/01/2004] [Accepted: 05/17/2004] [Indexed: 11/24/2022]
Abstract
The responses of mitogen-activated protein kinase (MAPK) family members, including the extracellular signal-regulated kinases (ERKs), the c-jun NH2-terminal kinases (JNKs) and p38MAPK, during mammalian hibernation were analyzed in five organs of Richardson's ground squirrels, Spermophilus richardsonii. Each kinase subfamily responded differently in torpor and each showed organ-specific patterns of response. ERK1/2 activities increased significantly in muscle and brain during hibernation but decreased in kidney and liver. JNK activity rose in four organs (except brain) during hibernation whereas active, phosphorylated p38MAPK increased only in muscle and heart. Activities of ERK-activated kinases also responded to hibernation: MAPKAPK-1 rose in muscle and brain, MAPKAPK-2 decreased in liver and kidney but rose in the other three organs, and p70S6K kinase activity decreased kidney and heart. Transcription factors, c-Jun and CREB, also showed organ-specific responses during torpor. The data suggest key roles for MAPKs in the regulation of the known organ-specific changes in gene expression and protein phosphorylation that define the hibernation phenotype.
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Affiliation(s)
- Justin A MacDonald
- Department of Biochemistry and Molecular Biology, University of Calgary, 3330 Hospital Drive N.W., Calgary, AB, Canada T2N 4N1
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Eddy SF, Morin P, Storey KB. Cloning and expression of PPARγ and PGC-1α from the hibernating ground squirrel, Spermophilus tridecemlineatus. Mol Cell Biochem 2005; 269:175-82. [PMID: 15786730 DOI: 10.1007/s11010-005-3459-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The peroxisome proliferator-activated receptor (PPAR) family of transcription factors play a key role in lipid metabolism and have been implicated in a number of disease states, most notably of which is obesity. Controlled regulation of lipid metabolism is a key ingredient for successful hibernation. Partial cDNA sequences for one of the PPAR proteins, PPARgamma and the PPARgamma co-activator (PGC-1alpha) have been cloned from the hibernating ground squirrel, Spermophilus tridecemlineatus and show differential regulation during hibernation at the mRNA level using relative RT-PCR and at the protein level via immunoblotting in brown adipose tissue (BAT), heart, skeletal muscle and white adipose tissue (WAT). The cDNA sequence for PGC-1alpha revealed a number of amino acid substitutions and two were worthy of note, one resulting in the loss of a potential protein kinase C (PKC) site, while another resulted in the creation of a PKC site, suggesting that PKC may be important in regulating PGC-1alpha. RT-PCR revealed a near 2-fold up-regulation of PPARgamma in BAT and to a lesser extent (<1.5-fold) in heart and WAT, while PGC-1alpha displayed significantly higher levels of expression in skeletal muscle during hibernation (3.1-fold, p < 0.005). The protein levels of PPARy were significantly increased in BAT and WAT (1.5 and 1.8-fold, respectively) while PGC-1alpha displayed significant changes in expression in heart (3.5-fold) and skeletal muscle (1.8-fold). Our current findings indicate a role for increased expression of PPARy and PGC-1alpha in hibernating animals.
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Affiliation(s)
- Sean F Eddy
- Institute of Biochemistry and Department of Chemistry, Carleton University, Ottawa, Canada.
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47
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Epperson LE, Dahl TA, Martin SL. Quantitative Analysis of Liver Protein Expression During Hibernation in the Golden-mantled Ground Squirrel. Mol Cell Proteomics 2004; 3:920-33. [PMID: 15266006 DOI: 10.1074/mcp.m400042-mcp200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammals that enter deep hibernation experience extreme reductions in body temperature and in metabolic, respiratory, and heart rates for several weeks at a time. Survival of these extremes likely entails a highly regulated network of tissue- and time-specific gene expression patterns that remain largely unknown. To date, studies to identify differentially-expressed genes have employed a candidate gene approach or in a few cases broader unbiased screens at the RNA level. Here we use a proteomic approach to compare and identify differentially expressed liver proteins from two seasonal stages in the golden-mantled ground squirrel (summer and entrance into torpor) using two-dimensional gels followed by MS/MS. Eighty-four two-dimensional gel spots were found that quantitatively alter with the hibernation season, 68 of which gave unambiguous identifications based on similarity to sequences in the available mammalian database. Based on what is known of these proteins from prior research, they are involved in a variety of cellular processes including protein turnover, detoxification, purine biosynthesis, gluconeogenesis, lipid metabolism and mobility, ketone body formation, cell structure, and redox balance. A number of the enzymes found to change seasonally are known to be either rate-limiting or first enzymes in a metabolic pathway, indicating key roles in metabolic control. Functional roles are proposed to explain the changes seen in protein levels and their potential influence on the phenotype of hibernation.
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Affiliation(s)
- L Elaine Epperson
- Program in Molecular Biology, Department of Cell and Developmental Biology, University of Colorado School of Medicine, P.O. Box 6511, Mail Stop 8108, Aurora, CO 80045, USA
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48
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Storey KB, Storey JM. Metabolic rate depression in animals: transcriptional and translational controls. Biol Rev Camb Philos Soc 2004; 79:207-33. [PMID: 15005178 DOI: 10.1017/s1464793103006195] [Citation(s) in RCA: 427] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metabolic rate depression is an important survival strategy for many animal species and a common element of hibernation, torpor, aestivation, anaerobiosis, diapause, and anhydrobiosis. Studies of the biochemical mechanisms that regulate reversible transitions to and from hypometabolic states are identifying principles of regulatory control that are conserved across phylogenetic lines and that are broadly applied to the control of multiple cell functions. One such mechanism is reversible protein phosphorylation which is now known to contribute to the regulation of fuel metabolism, to ion channel arrest, and to the suppression of protein synthesis during hypometabolism. The present review focuses on two new areas of research in hypometabolism: (1) the role of differential gene expression in supplying protein products that adjust metabolism or protect cell functions for long-term survival, and (2) the mechanisms of protein life extension in hypometabolism involving inhibitory controls of transcription, translation and protein degradation. Control of translation examines reversible phosphorylation regulation of ribosomal initiation and elongation factors, the dissociation of polysomes and storage of mRNA transcripts during hypometabolism, and control over the translation of different mRNA types by differential sequestering of mRNA into polysome versus monosome fractions. The analysis draws primarily from current research on two animal models, hibernating mammals and anoxia-tolerant molluscs, with selected examples from multiple other sources.
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Affiliation(s)
- Kenneth B Storey
- College of Natural Sciences, Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
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49
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Carey HV, Andrews MT, Martin SL. Mammalian hibernation: cellular and molecular responses to depressed metabolism and low temperature. Physiol Rev 2003; 83:1153-81. [PMID: 14506303 DOI: 10.1152/physrev.00008.2003] [Citation(s) in RCA: 785] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mammalian hibernators undergo a remarkable phenotypic switch that involves profound changes in physiology, morphology, and behavior in response to periods of unfavorable environmental conditions. The ability to hibernate is found throughout the class Mammalia and appears to involve differential expression of genes common to all mammals, rather than the induction of novel gene products unique to the hibernating state. The hibernation season is characterized by extended bouts of torpor, during which minimal body temperature (Tb) can fall as low as -2.9 degrees C and metabolism can be reduced to 1% of euthermic rates. Many global biochemical and physiological processes exploit low temperatures to lower reaction rates but retain the ability to resume full activity upon rewarming. Other critical functions must continue at physiologically relevant levels during torpor and be precisely regulated even at Tb values near 0 degrees C. Research using new tools of molecular and cellular biology is beginning to reveal how hibernators survive repeated cycles of torpor and arousal during the hibernation season. Comprehensive approaches that exploit advances in genomic and proteomic technologies are needed to further define the differentially expressed genes that distinguish the summer euthermic from winter hibernating states. Detailed understanding of hibernation from the molecular to organismal levels should enable the translation of this information to the development of a variety of hypothermic and hypometabolic strategies to improve outcomes for human and animal health.
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Affiliation(s)
- Hannah V Carey
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
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50
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Sallmen T, Lozada AF, Anichtchik OV, Beckman AL, Panula P. Increased brain histamine H3 receptor expression during hibernation in golden-mantled ground squirrels. BMC Neurosci 2003; 4:24. [PMID: 14505495 PMCID: PMC212552 DOI: 10.1186/1471-2202-4-24] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2003] [Accepted: 09/24/2003] [Indexed: 12/02/2022] Open
Abstract
Background Hibernation is a state of extremely reduced physiological functions and a deep depression of CNS activity. We have previously shown that the histamine levels increase in the brain during hibernation, as does the ratio between histamine and its first metabolite, suggesting increased histamine turnover during this state. The inhibitory histamine H3 receptor has both auto- and heteroreceptor function, rendering it the most likely histamine receptor to be involved in regulating the activity of histamine as well as other neurotransmitters during hibernation. In view of accumulating evidence that there is a global depression of transcription and translation during hibernation, of all but a few proteins that are important for this physiological condition, we reasoned that an increase in histamine H3 receptor expression would clearly indicate an important hibernation-related function for the receptor. Results In this study we show, using in situ hybridization, that histamine H3 receptor mRNA increases in the cortex, caudate nucleus and putamen during hibernation, an increase that is accompanied by elevated receptor binding in the cerebral cortex, globus pallidus and substantia nigra. These results indicate that there is a hibernation-related increase in H3 receptor expression in cortical neurons and in striatopallidal and striatonigral GABAergic neurons. GTP-γ-S binding autoradiography shows that the H3 receptors in the globus pallidus and substantia nigra can be stimulated by histamine throughout the hibernation cycle, suggesting that they are functionally active during hibernation. Conclusions These results show that the histamine H3 receptor gene is one of the few with a transcript that increases during hibernation, indicating an important role for the receptor in regulating this state. Moreover, the receptor is functionally active in the basal ganglia, suggesting a function for it in regulating e.g. dopaminergic transmission during hibernation.
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Affiliation(s)
- Tina Sallmen
- Department of Biology, Abo Akademi University, Åbo/Turku, Finland
| | - Adrian F Lozada
- Department of Biology, Abo Akademi University, Åbo/Turku, Finland
| | - Oleg V Anichtchik
- Department of Biology, Abo Akademi University, Åbo/Turku, Finland
- Institute for Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland
| | - Alexander L Beckman
- Department of Psychology, California State University, Long Beach, California
| | - Pertti Panula
- Department of Biology, Abo Akademi University, Åbo/Turku, Finland
- Institute for Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland
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