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TXNIP shuttling - a key molecular link in regulating inflammation and mitochondrial dysfunction in freeze tolerant wood frogs. Gene 2023; 857:147184. [PMID: 36627089 DOI: 10.1016/j.gene.2023.147184] [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: 08/19/2022] [Revised: 11/27/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023]
Abstract
Amphibians such as the wood frogs,Rana sylvatica, are a primary example of a freeze-tolerant vertebrate that undergoes whole body freezing. Multiple adaptations including sequestering 65-70% of total body water as extracellular/extra organ ice and producing massive amounts of glucose as a cryoprotectant support this. Interestingly, the high glucose levels induced in response to freezing can amplify oxidative stress's effects (reactive oxygen species, ROS) and induce inflammation and mitochondrial dysfunction. Since both freezing and dehydration stress (independent of freezing) can render wood frogs hyperglycemic, this study focussed on these two stresses to elucidate the role of a scaffold protein thioredoxin interacting protein (TXNIP), which localizes in multiple compartments inside the cell under hyperglycemic conditions and mediate diverse stress responses. The results from this study suggest a stress-specific response of TXNIP in inducing the cell-damaging pathway of inflammasome activation via its cytoplasmic localization during freezing. Interestingly, mitochondrial localization of TXNIP did not leads to increase in its binding to thioredoxin 2 (TRX-2) and activating the dysfunction of this organelle by releasing a mitochondrial protein cytochrome c (Cyt c) in cytoplasm under both freezing and dehydration stresses. Post-translational modifications of TXNIP hinted on changes in the regulating proteins involved in the inflammasome and mitochondrial dysfunction pathways, whereas sequential differences (cytosine residues) of amphibian TXNIP (compared to mammalian) assessed via 3D-modeling attributed to its weak binding to TRX-2. Overall, this study summarizes differential role of proteins activated under freeze and dehydration induced hyperglycemic response in freeze tolerant wood frogs.
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Storey JM, Li Z, Storey KB. Hypoxia inducible factor-1α responds to freezing, anoxia and dehydration stresses in a freeze-tolerant frog. Cryobiology 2023; 110:79-85. [PMID: 36442660 DOI: 10.1016/j.cryobiol.2022.11.242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 11/24/2022] [Accepted: 11/24/2022] [Indexed: 11/27/2022]
Abstract
The wood frog, Rana sylvatica (aka Lithobates sylvaticus) is the main model for studies of natural freeze tolerance among amphibians living in seasonally cold climates. During freezing, ∼65% of total body water can be converted to extracellular ice and this imposes both dehydration and hypoxia/anoxia stresses on cells. The current study analyzed the responses of the alpha subunit of the hypoxia-inducible transcription factor (HIF-1), a crucial oxygen-sensitive regulator of gene expression, to freezing, anoxia or dehydration stresses, examining six tissues of wood frogs (liver, skeletal muscle, brain, heart, kidney, skin). RT-PCR revealed a rapid elevation hif-1α transcript levels within 2 h of freeze initiation in both liver and brain and elevated levels of both mRNA and protein in liver and muscle after 24 h frozen. However, both transcript and protein levels reverted to control values after thawing except for HIF-1 protein in liver that dropped to ∼60% of control. Independent exposures of wood frogs to anoxia or dehydration stresses (two components of freezing) also triggered upregulation of hif-1α transcripts and/or HIF-1α protein in liver and kidney with variable responses in other tissues. The results show active modulation of HIF-1 in response to freezing, anoxia and dehydration stresses and implicate this transcription factor as a contributor to the regulation of metabolic adaptations needed for long term survival of wood frogs in the ischemic frozen state.
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Affiliation(s)
- Janet M Storey
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, Canada
| | - Zhenhong Li
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, K1S 5B6, Canada.
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3
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Niles J, Singh G, Storey KB. Role of unfolded protein response and ER-associated degradation under freezing, anoxia, and dehydration stresses in the freeze-tolerant wood frogs. Cell Stress Chaperones 2023; 28:61-77. [PMID: 36346580 PMCID: PMC9877271 DOI: 10.1007/s12192-022-01307-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/25/2022] [Accepted: 10/20/2022] [Indexed: 11/09/2022] Open
Abstract
The North American amphibian, wood frogs, Rana sylvatica are the most studied anuran to comprehend vertebrate freeze tolerance. Multiple adaptations support their survival in frigid temperatures during winters, particularly their ability to produce glucose as natural cryoprotectant. Freezing and its component consequences (anoxia and dehydration) induce multiple stresses on cells. Among these is endoplasmic reticulum (ER) stress, a condition spawned by buildup of unfolded or misfolded proteins in the ER. The ER stress causes the unfolded protein response (UPR) and the ER-associated degradation (ERAD) pathway that potentially could lead to apoptosis. Immunoblotting was used to assess the responses of major proteins of the UPR and ERAD under freezing, anoxia, and dehydration stresses in the liver and skeletal muscle of the wood frogs. Targets analyzed included activating transcription factors (ATF3, ATF4, ATF6), the growth arrest and DNA damage proteins (GADD34, GADD153), and EDEM (ERAD enhancing α-mannosidase-like proteins) and XBP1 (X-box binding protein 1) proteins. UPR signaling was triggered under all three stresses (freezing, anoxia, dehydration) in liver and skeletal muscle of wood frogs with most tissue/stress responses consistent with an upregulation of the primary targets of all three UPR pathways (ATF4, ATF6, and XBP-1) to enhance the protein folding/refolding capacity under these stress conditions. Only frozen muscle showed preference for proteasomal degradation of misfolded proteins via upregulation of EDEM (ERAD). The ERAD response of liver was downregulated across three stresses suggesting preference for more refolding of misfolded/unfolded proteins. Overall, we conclude that wood frog organs activate the UPR as a means of stabilizing and repairing cellular proteins to best survive freezing exposures.
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Affiliation(s)
- Jacques Niles
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Gurjit Singh
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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Al-Attar R, Storey KB. RAGE management: ETS1- EGR1 mediated transcriptional networks regulate angiogenic factors in wood frogs. Cell Signal 2022; 98:110408. [PMID: 35842171 DOI: 10.1016/j.cellsig.2022.110408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 07/02/2022] [Accepted: 07/11/2022] [Indexed: 11/03/2022]
Abstract
Freeze-tolerant species, such as wood frogs (Rana sylvatica), are susceptible to multiple co-occurring stresses that they must overcome to survive. Freezing is accompanied by mechanical stress and dehydration due to ice crystal formation in the extracellular space, ischemia/anoxia due to interruption in blood flood, and hyperglycemia due to cryoprotective measures. Wood frogs can survive dehydration, anoxia, and high glucose stress independently of freezing, thereby creating a multifactorial model for studying freeze-tolerance. Oxidative stress and high glucose levels favors the production of pro-oxidant molecules and advanced glycation end product (AGE) adducts that could cause substantial cellular damage. In this study, the involvement of the high mobility group box 1 (HMGB1)-AGE/RAGE (receptor for AGE) axis and the regulation of ETS1 and EGR1-mediated angiogenic responses were investigated in liver of wood frogs expose to freeze/thaw, anoxia/reoxygenation and dehydration/rehydration treatments. HMGB1 and not AGE-adducts are likely to induce the activation of ETS1 and EGR1 via the RAGE pathway. The increase in nuclear localization of both ETS1 and EGR1, but not DNA binding activity in response to stress hints to a potential spatial and temporal regulation in inducing angiogenic factors. Freeze/thaw and dehydration/rehydration treatments increase the levels of both pro- and anti-angiogenic factors, perhaps to prepare for the distribution of cryoprotectants or enable the repair of damaged capillaries and wounds when needed. Overall, wood frogs appear to anticipate the need for angiogenesis in response to freezing and dehydration but not anoxic treatments, probably due to mechanical stress associated with the two former conditions.
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Affiliation(s)
- Rasha Al-Attar
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S-5B6, Canada; McEwen Stem Cell Institute, University Health Network, Toronto, Ontario, Canada
| | - Kenneth B Storey
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S-5B6, Canada.
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Breedon SA, Gupta A, Storey KB. Regulation of Apoptosis and Autophagy During Anoxia in the Freshwater Crayfish, Faxonius virilis. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:626-639. [PMID: 35567599 DOI: 10.1007/s10126-022-10132-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The ability of an animal to survive prolonged periods of oxygen deprivation is a critical area of study, both in terms of its importance to better understanding the physiology of these incredible animals and to its potential applicability to medical fields. The freshwater crayfish, Faxonius virilis, is one such animal capable of resisting anoxia, but it remains understudied and much of the metabolic mechanisms underlying this anoxia tolerance remain largely unprofiled. This study examines the activity and regulation of apoptosis and autophagy in F. virilis in response to 20-h anoxia. Apoptosis signaling was assessed through pro- and anti-apoptosis targets, whereas autophagy was assessed via expression response of multiple autophagy proteins. An anoxia-triggered, tissue-specific result arose, potentially based on the importance of individual organ integrity through hypometabolism. Tail muscle, which showed increased expression profiles of all three target groups, contrasted with hepatopancreas, which appeared to not be susceptible to either apoptotic or autophagic signaling during anoxia. This is likely due to the importance of the hepatopancreas, given that apoptosis or autophagy of this organ at any significant level could be fatal to the organism. The data provides a comprehensive overview of the responses and integration of multiple stress-responsive signaling pathways in F. virilis that provide a novel contribution to our understanding of pro-survival mechanisms supporting invertebrate anoxia resistance.
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Affiliation(s)
- Sarah A Breedon
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Aakriti Gupta
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada.
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Hayashi Y, Nakajima Y, Sugiyama H. Computational screening of cryoprotective agents for regenerative medical products using quantum chemistry and molecular dynamics simulations. Cryobiology 2021; 100:101-109. [PMID: 33766526 DOI: 10.1016/j.cryobiol.2021.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 12/26/2022]
Abstract
Cryoprotective agents (CPAs) are essential for the cryopreservation of cells. Thus far, dimethyl sulfoxide (DMSO) has been widely used as a CPA; however, DMSO is known to be toxic to cells. The damaged cells by the toxicity can present abnormal conditions, and should not be used for regenerative medical products because the cells/products are implanted directly into human bodies. With the aim of searching for an alternative CPA to DMSO, this work presents a computational screening of CPA candidate compounds using quantum chemistry and molecular dynamics (MD) simulations. Forty compounds were evaluated in regard to the solvation free energy and partition coefficient by quantum chemistry simulation and the root mean square deviation (RMSD) of a phospholipid bilayer which composes a cell membrane by MD simulation. The solvation free energy, partition coefficient, and RMSD were defined as indicators of osmoregulatory ability, affinity with a cell membrane, and ability to spread a cell membrane, respectively. The quantum chemistry simulation elucidated that the six compounds of trimethylglycine, formamide, urea, thiourea, diethylene glycol, and dulcitol were better than DMSO in either or both of the physical properties considered. This finding is based on the inherent physical property and is thus case-independent. Further characterization with the MD simulation suggested that formamide, thiourea, and urea should be the first candidates to investigate, although the result was valid only in the simulated condition. This work serves as the first step of multi-faceted computational evaluation of multiple compounds in the search for an effective CPA compound after DMSO.
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Affiliation(s)
- Yusuke Hayashi
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656, Tokyo, Japan
| | - Yuka Nakajima
- Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656, Tokyo, Japan
| | - Hirokazu Sugiyama
- Department of Chemical System Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, 113-8656, Tokyo, Japan.
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7
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Al-Attar R, Storey KB. RAGE against the stress: Mitochondrial suppression in hypometabolic hearts. Gene 2020; 761:145039. [PMID: 32777527 DOI: 10.1016/j.gene.2020.145039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/19/2020] [Accepted: 08/04/2020] [Indexed: 12/22/2022]
Abstract
The wood frog (Rana sylvatica) can tolerate full body freezing in winter. As a protective response, wood frogs dehydrate their cells and accumulate large quantities of glucose as an intracellular cryoprotectant. Freezing causes ischemia since blood delivery to organs is interrupted. Fascinatingly, wood frogs can tolerate dehydration, extreme hyperglycemia, and anoxia independently of freezing. In response to low oxygen levels, wood frogs strategically reduce their metabolic rates and allocate the finite amount of intracellular fuel available to pro-survival processes while reducing or interrupting all others. In this study, the involvement of advanced glycation end products (AGEs) and the high mobility group box 1 (HMGB1) protein in activating RAGE (AGE receptor) were investigated. The results show that freezing, anoxia and dehydration induced the expression of total HMGB1 and its acetylation in the heart. RAGE levels were induced in response to all stress conditions, which resulted in differential regulation of the ETS1 transcription factor. While the nuclear localization of total ETS1 was not affected, the DNA binding activity of total and its active form increased in response to freezing and dehydration but not in response to anoxia. Current results indicate that ETS1 acts as a transcriptional activator for peroxiredoxin 1 in response to freezing but acts as a transcriptional repressor of several nuclear-encoded mitochondrial genes in response to all stresses. Altogether, current results show that the HMGB1/RAGE axis may activate ETS1 and that this activation could result in both transcriptional activation and/or repression in a stress-dependent manner.
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Affiliation(s)
- Rasha Al-Attar
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S-5B6, Canada
| | - Kenneth B Storey
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, ON K1S-5B6, Canada.
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8
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Al-attar R, Wu CW, Biggar KK, Storey KB. Carb-Loading: Freeze-Induced Activation of the Glucose-Responsive ChREBP Transcriptional Network in Wood Frogs. Physiol Biochem Zool 2020; 93:49-61. [DOI: 10.1086/706463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Herman BA, Ferguson KM, Fernandez JVB, Kauffman S, Spicher JT, King RJ, Halterman JA. NFAT5 is differentially expressed in Sprague-Dawley rat tissues in response to high salt and high fructose diets. Genet Mol Biol 2019; 42:452-464. [PMID: 30816906 PMCID: PMC6726159 DOI: 10.1590/1678-4685-gmb-2018-0120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 07/24/2018] [Indexed: 12/31/2022] Open
Abstract
Current diets contain an increasing amount of salt and high fructose corn syrup,
but it remains unclear as to how dietary salt and fructose affect organ function
at the molecular level. This study aimed to test the hypothesis that consumption
of high salt and fructose diets would increase tissue-specific expression of two
critical osmotically-regulated genes, nuclear factor of activated T-cells 5
(NFAT5) and aldose reductase (AR). Fifty
Sprague-Dawley rats were placed on a control, 4% NaCl, 8% NaCl, or 64% fructose
diet for eight weeks. Fourteen different tissue samples were harvested and
snap-frozen, followed by RNA purification, cDNA synthesis, and
NFAT5 and AR gene expression
quantification by real-time PCR.Our findings demonstrate that
NFAT5 and AR expression are up-regulated
in the kidney medulla, liver, brain, and adipose tissue following consumption of
a high salt diet. NFAT5 expression is also up-regulated in the
kidney cortex following consumption of a 64% fructose diet. These findings
highlight the kidney medulla, liver, brain, and adipose tissue as being
“salt-responsive” tissues and reveal that a high fructose diet can lead to
enhanced NFAT5 expression in the kidney cortex. Further
characterization of signaling mechanisms involved could help elucidate how these
diets affect organ function long term.
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Affiliation(s)
- Braden A Herman
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Kaylee M Ferguson
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Jared V B Fernandez
- Master's in Biomedicine Program, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Samantha Kauffman
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Jason T Spicher
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Rachel J King
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA
| | - Julia A Halterman
- Department of Biology, Eastern Mennonite University, Harrisonburg, VA, USA.,Master's in Biomedicine Program, Eastern Mennonite University, Harrisonburg, VA, USA
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Sanchez-Lozada LG, Andres-Hernando A, Garcia-Arroyo FE, Cicerchi C, Li N, Kuwabara M, Roncal-Jimenez CA, Johnson RJ, Lanaspa MA. Uric acid activates aldose reductase and the polyol pathway for endogenous fructose and fat production causing development of fatty liver in rats. J Biol Chem 2019; 294:4272-4281. [PMID: 30651350 DOI: 10.1074/jbc.ra118.006158] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/10/2019] [Indexed: 12/18/2022] Open
Abstract
Dietary, fructose-containing sugars have been strongly associated with the development of nonalcoholic fatty liver disease (NAFLD). Recent studies suggest that fructose also can be produced via the polyol pathway in the liver, where it may induce hepatic fat accumulation. Moreover, fructose metabolism yields uric acid, which is highly associated with NAFLD. Here, using biochemical assays, reporter gene expression, and confocal fluorescence microscopy, we investigated whether uric acid regulates aldose reductase, a key enzyme in the polyol pathway. We evaluated whether soluble uric acid regulates aldose reductase expression both in cultured hepatocytes (HepG2 cells) and in the liver of hyperuricemic rats and whether this stimulation is associated with endogenous fructose production and fat accumulation. Uric acid dose-dependently stimulated aldose reductase expression in the HepG2 cells, and this stimulation was associated with endogenous fructose production and triglyceride accumulation. This stimulatory mechanism was mediated by uric acid-induced oxidative stress and stimulation of the transcription factor nuclear factor of activated T cells 5 (NFAT5). Uric acid also amplified the effects of elevated glucose levels to stimulate hepatocyte triglyceride accumulation. Hyperuricemic rats exhibited elevated hepatic aldose reductase expression, endogenous fructose accumulation, and fat buildup that was significantly reduced by co-administration of the xanthine oxidase inhibitor allopurinol. These results suggest that uric acid generated during fructose metabolism may act as a positive feedback mechanism that stimulates endogenous fructose production by stimulating aldose reductase in the polyol pathway. Our findings suggest an amplifying mechanism whereby soft drinks rich in glucose and fructose can induce NAFLD.
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Affiliation(s)
- Laura G Sanchez-Lozada
- From the Laboratory of Renal Physiopathology, Instituto Nacional de Cardiología Ignacio Chavez, CP 14080 Mexico City, Mexico and
| | - Ana Andres-Hernando
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Fernando E Garcia-Arroyo
- From the Laboratory of Renal Physiopathology, Instituto Nacional de Cardiología Ignacio Chavez, CP 14080 Mexico City, Mexico and
| | - Christina Cicerchi
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Nanxing Li
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Masanari Kuwabara
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Carlos A Roncal-Jimenez
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Richard J Johnson
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Miguel A Lanaspa
- the Division of Renal Diseases and Hypertension, School of Medicine, University of Colorado, Aurora, Colorado 80045
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Al-Attar R, Wijenayake S, Storey KB. Metabolic reorganization in winter: Regulation of pyruvate dehydrogenase (PDH) during long-term freezing and anoxia. Cryobiology 2019; 86:10-18. [PMID: 30639451 DOI: 10.1016/j.cryobiol.2019.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/19/2018] [Accepted: 01/09/2019] [Indexed: 12/16/2022]
Abstract
Wood frogs, Rana sylvatica, can undergo prolonged periods of whole body freezing during winter, locking as much as 65-70% of total body water into extracellular ice and imposing both anoxia and dehydration on their cells. Metabolic rate depression (MRD) is an adaptation used by R. sylvatica to survive these environmental stresses, where a finite amount of ATP generated through anaerobic metabolism is directed towards maintaining pro-survival functions, while most ATP-expensive cellular processes are temporarily reduced in function. Pyruvate dehydrogenase (PDH) is a vital metabolic enzyme that links anaerobic glycolysis to the aerobic TCA cycle and is an important regulatory site in MRD. PDH enzymatic activity is regulated via reversible protein phosphorylation in response to energetic demands of cells. This study explored the posttranslational regulation of PDH at three serine sites (S232, S293, S300) on the catalytic E1α subunit along with protein expression of four pyruvate dehydrogenase kinases (PDHK1-4) in response to 24 h Freezing, 8 h Thaw, 24 h Anoxia, and 4 h Recovery in the liver and skeletal muscle of R. sylvatica using Luminex multiplex technology and western immunoblotting. Overall, inhibitory regulation of PDH was evident during 24 h Freezing and 24 h Anoxia, which could indicate a notable reduction in glycoytic flux and carbon entry into the tricarboxylic acid cycle as part of MRD. Furthermore, the expression of PDHK1-4 and phosphorylation of PDH at S232, S293, and S300 were highly tissue and stress-specific, indicative of how different tissues respond differently to stress within the same organism.
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Affiliation(s)
- Rasha Al-Attar
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Sanoji Wijenayake
- Department of Biology, Carleton University, Ottawa, Ontario, Canada; Center for Environmental Epigenetics and Development, Biological Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, Ontario, Canada.
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12
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Al-Attar R, Storey KB. Effects of anoxic exposure on the nuclear factor of activated T cell (NFAT) transcription factors in the stress-tolerant wood frog. Cell Biochem Funct 2018; 36:420-430. [PMID: 30411386 DOI: 10.1002/cbf.3362] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 08/15/2018] [Accepted: 10/03/2018] [Indexed: 11/08/2022]
Abstract
The wood frog, Lithobates sylvaticus (also known as Rana sylvatica), is used for studying natural freeze tolerance. These animals convert 65% to 70% of their total body water into extracellular ice and survive freezing for weeks in winter. Freezing interrupts oxygen delivery to organs; thus, wood frogs limit their ATP usage by depressing their metabolism and redirecting the available energy only to prosurvival processes. Here, we studied the nuclear factor of activated T cell (NFAT) transcription factor family in response to 24-hour anoxia, and 4-hour aerobic recovery in liver and skeletal muscle. Protein expression levels of NFATc1-c4, calcineurin A and glycogen synthase kinase 3β (NFAT regulators), osteopontin, and atrial natriuretic peptide (ANP) (targets of NFATc3 and NFATc4, respectively) were measured by immunoblotting, and the DNA-binding activities of NFATc1-c4 were measured by DNA-protein interaction ELISAs. Results show that NFATc4, calcineurin, and ANP protein expression as well as NFATc4 DNA binding increased during anoxia in liver where calcineurin and ANP protein levels and NFATc4 DNA binding remaining high after aerobic recovery. Anoxia caused a significant increase in NFATc3 protein expression but not DNA-binding activity in muscle. Our results show that anoxia can increase NFATc4 transcriptional activity in liver, leading to the increase in expression of cytoprotective genes in the wood frog. Understanding the molecular mechanisms involved in mediating survival under anoxia/reoxygenation conditions in a naturally stress-tolerant model, such as the wood frog, provides insightful information on the prosurvival regulatory mechanisms involved in combating stress. This information will also further our understanding of metabolic rate depression and answer the question of how frogs tolerate prolonged periods of oxygen deprivation and resume to full function upon recovery without facing any detrimental side effects as other animals would.
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Affiliation(s)
- Rasha Al-Attar
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, Canada
| | - Kenneth B Storey
- Institude of Biochemistry and Department of Biology, Carleton University, Ottawa, Canada
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13
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English SG, Hadj-Moussa H, Storey KB. MicroRNAs regulate survival in oxygen-deprived environments. J Exp Biol 2018; 221:jeb.190579. [DOI: 10.1242/jeb.190579] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/07/2018] [Indexed: 12/13/2022]
Abstract
Some animals must endure prolonged periods of oxygen deprivation to survive. One such extreme model is the Northern Crayfish (Orconectes virilis), that regularly survives year-round hypoxic and anoxic stresses in its warm stagnant summer waters and in its cold, ice-locked winter waters. To elucidate the molecular underpinnings of anoxia-resistance in this natural model, we surveyed the expression profiles of 76 highly-conserved microRNAs in crayfish hepatopancreas and tail muscle from normoxic, acute 2hr anoxia, and chronic 20hr anoxia exposures. MicroRNAs are known to regulate a diverse array of cellular functions required for environmental stress adaptations, and here we explore their role in anoxia tolerance. The tissue-specific anoxia responses observed herein, with 22 anoxia-responsive microRNAs in hepatopancreas and only 4 changing microRNAs in muscle, suggest that microRNAs facilitate a reprioritization of resources to preserve crucial organ functions. Bioinformatic microRNA target enrichment analysis predicted that the anoxia-downregulated microRNAs in hepatopancreas targeted hippo-signalling, suggesting that cell proliferation and apoptotic signalling are highly regulated in this liver-like organ during anoxia. Compellingly, miR-125-5p, miR-33-5p, and miR-190-5p, all known to target the master regulator of oxygen deprivation responses HIF1 (Hypoxia Inducible Factor-1), were anoxia-downregulated in hepatopancreas. The anoxia-increased transcript levels of the oxygen dependent subunit HIF1α, highlight a potential critical role for miRNA-HIF targeting in facilitating a successful anoxia response. Studying the cytoprotective mechanisms in place to protect against the challenges associated with surviving in oxygen-poor environments is critical to elucidating microRNAs’ vast and substantial role in the regulation of metabolism and stress in aquatic invertebrates.
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Affiliation(s)
- Simon G. English
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Hanane Hadj-Moussa
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B. Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
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Zhang Y, Al-attar R, Storey KB. TonEBP/NFAT5 regulates downstream osmoregulatory proteins during freeze-thaw stress in the wood frog. Cryobiology 2017; 79:43-49. [DOI: 10.1016/j.cryobiol.2017.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 12/19/2022]
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Hoyeck MP, Hadj-Moussa H, Storey KB. The role of MEF2 transcription factors in dehydration and anoxia survival in Rana sylvatica skeletal muscle. PeerJ 2017; 5:e4014. [PMID: 29134152 PMCID: PMC5682099 DOI: 10.7717/peerj.4014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/19/2017] [Indexed: 11/20/2022] Open
Abstract
The wood frog (Rana sylvatica) can endure freezing of up to 65% of total body water during winter. When frozen, wood frogs enter a dormant state characterized by a cessation of vital functions (i.e., no heartbeat, blood circulation, breathing, brain activity, or movement). Wood frogs utilize various behavioural and biochemical adaptations to survive extreme freezing and component anoxia and dehydration stresses, including a global suppression of metabolic functions and gene expression. The stress-responsive myocyte enhancer factor-2 (MEF2) transcription factor family regulates the selective expression of genes involved in glucose transport, protein quality control, and phosphagen homeostasis. This study examined the role of MEF2A and MEF2C proteins as well as select downstream targets (glucose transporter-4, calreticulin, and muscle and brain creatine kinase isozymes) in 40% dehydration and 24 h anoxia exposure at the transcriptional, translational, and post-translational levels using qRT-PCR, immunoblotting, and subcellular localization. Mef2a/c transcript levels remained constant during dehydration and anoxia. Total, cytoplasmic, and nuclear MEF2A/C and phospho-MEF2A/C protein levels remained constant during dehydration, whereas a decrease in total MEF2C levels was observed during rehydration. Total and phospho-MEF2A levels remained constant during anoxia, whereas total MEF2C levels decreased during 24 h anoxia and P-MEF2C levels increased during 4 h anoxia. In contrast, cytoplasmic MEF2A levels and nuclear phospho-MEF2A/C levels were upregulated during anoxia. MEF2 downstream targets remained constant during dehydration and anoxia, with the exception of glut4 which was upregulated during anoxia. These results suggest that the upregulated MEF2 response reported in wood frogs during freezing may in part stem from their cellular responses to surviving prolonged anoxia, rather than dehydration, leading to an increase in GLUT4 expression which may have an important role during anoxia survival.
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Affiliation(s)
- Myriam P Hoyeck
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
| | - Hanane Hadj-Moussa
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
| | - Kenneth B Storey
- Institute of Biochemistry, Departments of Biology and Chemistry, Carleton University, Ottawa, Canada
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