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Gupta R, Chauhan A, Kaur T, Kuanr BK, Sharma D. Enhancing Magnetic Hyperthermia Efficacy through Targeted Heat Shock Protein 90 Inhibition: Unveiling Immune-Mediated Therapeutic Synergy in Glioma Treatment. ACS NANO 2024. [PMID: 38906828 DOI: 10.1021/acsnano.4c03887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
The induction of heat stress response (HSR) mediated by the generation of heat shock proteins (HSPs) on exposure to magnetic hyperthermia-mediated cancer therapy (MHCT) decreases the efficacy of localized heat treatment at the tumor site, and thus therapy remains a significant challenge. Hence, the present study examined differential HSR elicited in glioma cells post-MHCT under different tumor microenvironment conditions (2D monolayers, 3D monoculture, and coculture spheroids) to recognize target genes that, when downregulated, could enhance the therapeutic effect of MHCT. Gene expression analysis following MHCT revealed that HSP90 was upregulated as compared to HSP70. Hence, to enhance the efficacy of the treatment, a combinatorial strategy using 17-DMAG as an inhibitor of HSP90 following MHCT was investigated. The effects of combinatorial therapy in terms of cell viability, HSP levels by immunofluorescence and gene expression analysis, oxidative stress generation, and alterations in cellular integrity were evaluated, where combinatorial therapy demonstrated an enhanced therapeutic outcome with maximum glioma cell death. Further, in the murine glioma model, a rapid tumor inhibition of 65 and 53% was observed within 8 days at the primary and secondary tumor sites, respectively, in the MCHT + 17-DMAG group, with abscopal effect-mediated complete tumor inhibition at both the tumor sites within 20 days of MHCT. The extracellularly released HSP90 from dying tumor cells further suggested the induction of immune response supported by the upregulation of IFN-γ and calreticulin genes in the MHCT + 17-DMAG group. Overall, our findings indicate that MHCT activates host immune systems and efficiently cooperates with the HSP90 blockade to inhibit the growth of distant metastatic tumors.
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Affiliation(s)
- Ruby Gupta
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali, Punjab 140306, India
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, United States
| | - Anjali Chauhan
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali, Punjab 140306, India
- Special Centre for Nanoscience, Jawaharlal Nehru University, New Delhi 110067, India
| | - Tashmeen Kaur
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali, Punjab 140306, India
| | - Bijoy Kumar Kuanr
- Special Centre for Nanoscience, Jawaharlal Nehru University, New Delhi 110067, India
| | - Deepika Sharma
- Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali, Punjab 140306, India
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Storey JM, Storey KB. Chaperone proteins: universal roles in surviving environmental stress. Cell Stress Chaperones 2023; 28:455-466. [PMID: 36441380 PMCID: PMC10469148 DOI: 10.1007/s12192-022-01312-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/29/2022] Open
Abstract
Chaperone proteins have crucial roles to play in all animal species and are involved in mediating both the folding of newly synthesized peptides into their mature conformation, the refolding of misfolded proteins, and the trafficking of proteins between subcellular compartments. These highly conserved proteins have particularly important roles to play in dealing with disruptions of the proteome as a result of environmental stress since abiotic factors, including temperature, pressure, oxygen, water availability, and pollutants can readily disrupt the conformation and/or function of all types of proteins, e.g., enzymes, transporters, and structural proteins. The current review provides an update on recent advances in understanding the roles and responses of chaperones in aiding animals to deal with environmental stress, offering new information on chaperone action in supporting survival strategies including torpor, hibernation, anaerobiosis, estivation, and cold/freeze tolerance among both vertebrate and invertebrate species.
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Affiliation(s)
- Janet M Storey
- 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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Zhang S, Ishida Y, Ishigami A, Nosaka M, Kuninaka Y, Yasuda H, Kofuna A, Matsuki J, Osako M, Zhang W, Kimura A, Furukawa F, Kondo T. Forensic application of epidermal expression of HSP27 and HSP70 for the determination of wound vitality in human compressed neck skin. Sci Rep 2023; 13:6692. [PMID: 37095183 PMCID: PMC10126125 DOI: 10.1038/s41598-023-33799-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 04/19/2023] [Indexed: 04/26/2023] Open
Abstract
Estimating the age and vitality of human skin wounds is essential in forensic practice, and the use of immunohistochemical parameters in this regard remains a challenge. Heat shock proteins (HSPs) are evolutionarily conserved universal proteins that protect biological systems from various types of stress. However, its importance in forensic pathology for determining wound activation in neck compression skin remains unclear. The expression of HSP27 and HSP70 in neck skin samples was immunohistochemically examined to understand its forensic applicability in determining wound vitality. Skin samples were obtained from 45 cases of neck compression (hanging, 32 cases; strangulation, 10 cases; manual strangulation, 2 cases; other, 1 case) during forensic autopsies; intact skin from the same individual was used as a control. HSP27 expression was detected in 17.4% of keratinocytes in the intact skin samples. In the compressed region, the frequency of HSP27 expression in keratinocytes was 75.8%, which was significantly higher than that in intact skin. Similarly, HSP70 expression was 24.8% in intact skin samples and 81.9% in compressed skin samples, significantly higher in compressed skin than in intact skin samples. This increase in case compression cases may be due to the cell defence role of HSPs. From a forensic pathology perspective, the immunohistochemical examination of HSP27 and HSP70 expression in neck skin could be considered a valuable marker for diagnosing traces of antemortem compression.
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Affiliation(s)
- Siying Zhang
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yuko Ishida
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
| | - Akiko Ishigami
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Mizuho Nosaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yumi Kuninaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Haruki Yasuda
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Ayumi Kofuna
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Jumpei Matsuki
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Miyu Osako
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Wei Zhang
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Akihiko Kimura
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Fukumi Furukawa
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Toshikazu Kondo
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
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Hawrysh PJ, Myrka AM, Buck LT. Review: A history and perspective of mitochondria in the context of anoxia tolerance. Comp Biochem Physiol B Biochem Mol Biol 2022; 260:110733. [PMID: 35288242 DOI: 10.1016/j.cbpb.2022.110733] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/07/2022] [Accepted: 03/07/2022] [Indexed: 01/01/2023]
Abstract
Symbiosis is found throughout nature, but perhaps nowhere is it more fundamental than mitochondria in all eukaryotes. Since mitochondria were discovered and mechanisms of oxygen reduction characterized, an understanding gradually emerged that these organelles were involved not just in the combustion of oxygen, but also in the sensing of oxygen. While multiple hypotheses exist to explain the mitochondrial involvement in oxygen sensing, key elements are developing that include potassium channels and reactive oxygen species. To understand how mitochondria contribute to oxygen sensing, it is informative to study a model system which is naturally adapted to survive extended periods without oxygen. Amongst air-breathing vertebrates, the most highly adapted are western painted turtles (Chrysemys picta bellii), which overwinter in ice-covered and anoxic water bodies. Through research of this animal, it was postulated that metabolic rate depression is key to anoxic survival and that mitochondrial regulation is a key aspect. When faced with anoxia, excitatory neurotransmitter receptors in turtle brain are inhibited through mitochondrial calcium release, termed "channel arrest". Simultaneously, inhibitory GABAergic signalling contributes to the "synaptic arrest" of excitatory action potential firing through a pathway dependent on mitochondrial depression of ROS generation. While many pathways are implicated in mitochondrial oxygen sensing in turtles, such as those of adenosine, ATP turnover, and gaseous transmitters, an apparent point of intersection is the mitochondria. In this review we will explore how an organelle that was critical for organismal complexity in an oxygenated world has also become a potentially important oxygen sensor.
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Affiliation(s)
- Peter John Hawrysh
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Alexander Morley Myrka
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Leslie Thomas Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada; Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.
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Abstract
ABSTRACT
Hypoxia is one of the strongest environmental drivers of cellular and physiological adaptation. Although most mammals are largely intolerant of hypoxia, some specialized species have evolved mitigative strategies to tolerate hypoxic niches. Among the most hypoxia-tolerant mammals are naked mole-rats (Heterocephalus glaber), a eusocial species of subterranean rodent native to eastern Africa. In hypoxia, naked mole-rats maintain consciousness and remain active despite a robust and rapid suppression of metabolic rate, which is mediated by numerous behavioural, physiological and cellular strategies. Conversely, hypoxia-intolerant mammals and most other hypoxia-tolerant mammals cannot achieve the same degree of metabolic savings while staying active in hypoxia and must also increase oxygen supply to tissues, and/or enter torpor. Intriguingly, recent studies suggest that naked mole-rats share many cellular strategies with non-mammalian vertebrate champions of anoxia tolerance, including the use of alternative metabolic end-products and potent pH buffering mechanisms to mitigate cellular acidification due to upregulation of anaerobic metabolic pathways, rapid mitochondrial remodelling to favour increased respiratory efficiency, and systemic shifts in energy prioritization to maintain brain function over that of other tissues. Herein, I discuss what is known regarding adaptations of naked mole-rats to a hypoxic lifestyle, and contrast strategies employed by this species to those of hypoxia-intolerant mammals, closely related African mole-rats, other well-studied hypoxia-tolerant mammals, and non-mammalian vertebrate champions of anoxia tolerance. I also discuss the neotenic theory of hypoxia tolerance – a leading theory that may explain the evolutionary origins of hypoxia tolerance in mammals – and highlight promising but underexplored avenues of hypoxia-related research in this fascinating model organism.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7. University of Ottawa, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada, K1H 8M5
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Lari E, Buck LT. Exposure to low temperature prepares the turtle brain to withstand anoxic environments during overwintering. J Exp Biol 2021; 224:272110. [PMID: 34498078 DOI: 10.1242/jeb.242793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 08/27/2021] [Indexed: 11/20/2022]
Abstract
In most vertebrates, anoxia drastically reduces the production of the essential adenosine triphosphate (ATP) to power its many necessary functions, and, consequently, cell death occurs within minutes. However, some vertebrates, such as the painted turtle (Chrysemys picta bellii), have evolved the ability to survive months without oxygen by simultaneously decreasing ATP supply and demand, surviving the anoxic period without any apparent cellular damage. The impact of anoxia on the metabolic function of painted turtles has received a lot of attention. However, the impact of low temperature has received less attention and the interactive effect of anoxia and temperature even less. In the present study, we investigated the interactive impacts of reduced temperature and severe hypoxia on the electrophysiological properties of pyramidal neurons in painted turtle cerebral cortex. Our results show that an acute reduction in temperature from 20 to 5°C decreases membrane potential, action potential width and amplitude, and whole-cell conductance. Importantly, acute exposure to 5°C considerably slows membrane repolarization by voltage-gated K+ channels. Exposing pyramidal cells to severe hypoxia in addition to an acute temperature change slightly depolarized membrane potential but did not alter action potential amplitude or width and whole-cell conductance. These results suggest that acclimation to low temperatures, preceding severe environmental hypoxia, induces cellular responses in pyramidal neurons that facilitate survival under low oxygen concentrations. In particular, our results show that temperature acclimation invokes a change in voltage-gated K+ channel kinetics that overcomes the acute inhibition of the channel.
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Affiliation(s)
- Ebrahim Lari
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada, M5S 3G5.,Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E9
| | - Leslie T Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada, M5S 3G5.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada, M5S 3B2
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Pillai V, Buck L, Lari E. Scavenging of reactive oxygen species mimics the anoxic response in goldfish pyramidal neurons. J Exp Biol 2021; 224:268949. [PMID: 34047778 DOI: 10.1242/jeb.238147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 04/20/2021] [Indexed: 12/11/2022]
Abstract
Goldfish are one of a few species able to avoid cellular damage during month-long periods in severely hypoxic environments. By suppressing action potentials in excitatory glutamatergic neurons, the goldfish brain decreases its overall energy expenditure. Coincident with reductions in O2 availability is a natural decrease in cellular reactive oxygen species (ROS) generation, which has been proposed to function as part of a low-oxygen signal transduction pathway. Using live-tissue fluorescence microscopy, we found that ROS production decreased by 10% with the onset of anoxia in goldfish telencephalic brain slices. Employing whole-cell patch-clamp recording, we found that, similar to severe hypoxia, the ROS scavengers N-acetyl cysteine (NAC) and MitoTEMPO, added during normoxic periods, depolarized membrane potential (severe hypoxia -73.6 to -61.4 mV, NAC -76.6 to -66.2 mV and MitoTEMPO -71.5 mV to -62.5 mV) and increased whole-cell conductance (severe hypoxia 5.7 nS to 8.0 nS, NAC 6.0 nS to 7.5 nS and MitoTEMPO 6.0 nS to 7.6 nS). Also, in a subset of active pyramidal neurons, these treatments reduced action potential firing frequency (severe hypoxia 0.18 Hz to 0.03 Hz, NAC 0.27 Hz to 0.06 Hz and MitoTEMPO 0.35 Hz to 0.08 Hz). Neither severe hypoxia nor ROS scavenging impacted action potential threshold. The addition of exogenous hydrogen peroxide could reverse the effects of the antioxidants. Taken together, this supports a role for a reduction in [ROS] as a low-oxygen signal in goldfish brain.
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Affiliation(s)
- Varshinie Pillai
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada, M3A 3A7
| | - Leslie Buck
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada, M3A 3A7
| | - Ebrahim Lari
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada, M3A 3A7
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Tan K, Zhang B, Ma H, Li S, Zheng H. Oxidative stress responses of golden and brown noble scallops Chlamys nobilis to acute cold stress. FISH & SHELLFISH IMMUNOLOGY 2019; 95:349-356. [PMID: 31678188 DOI: 10.1016/j.fsi.2019.10.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/15/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
The noble scallop Chlamys nobilis is an important edible marine bivalve that is widely cultivated in the sea of southern China. Unfortunately, the mass mortality of noble scallops frequently occurs during the winter months. The present study investigated the effects of acute cold stress (8 °C) to the physiological responses of polymorphic noble scallops, by assessing the HSP70 gene expression, total carotenoid content (TCC), total antioxidant capacity (TAC), malondialdehyde (MDA) content, catalase (CAT) activity and superoxide dismutase (SOD) enzymatic activity in different tissues of golden and brown scallops. The results of the present study revealed that MDA, TCC and CAT increased drastically in most tissues in the early stage of acute cold stress (0-3 h), but TCC, SOD and CAT generally showed a downward trend. Within 3-6 h of acute cold stress, MDA content decreased in most tissues and the SOD content increased significantly in most tissues, while TCC and CAT remained at peak. After 6 h of acute cold stress, MDA content continued to increase in most tissues, while TCC, CAT, SOD and TAC decreased or remained at a lower level. For HSP70 expression, up-regulation of the HSP70 gene was observed only in mantle of brown scallops and hemolymph of golden scallops at 3 h and 24 h, respectively. The findings of the present study can better understand the physiological response of noble scallops to acute cold stress.
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Affiliation(s)
- Karsoon Tan
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, 515063, China; Mariculture Research Center for Subtropical Shellfish & Algae of Guangdong Province, Shantou, 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou, 515063, China
| | - Bo Zhang
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, 515063, China
| | - Hongyu Ma
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, 515063, China; Mariculture Research Center for Subtropical Shellfish & Algae of Guangdong Province, Shantou, 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou, 515063, China
| | - Shengkang Li
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, 515063, China; Mariculture Research Center for Subtropical Shellfish & Algae of Guangdong Province, Shantou, 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou, 515063, China
| | - Huaiping Zheng
- Key Laboratory of Marine Biotechnology of Guangdong Province, Shantou University, Shantou, 515063, China; Mariculture Research Center for Subtropical Shellfish & Algae of Guangdong Province, Shantou, 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou, 515063, China.
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Storey JM, Storey KB. In defense of proteins: Chaperones respond to freezing, anoxia, or dehydration stress in tissues of freeze tolerant wood frogs. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2019; 331:392-402. [PMID: 31276323 DOI: 10.1002/jez.2306] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 01/02/2023]
Abstract
Wood frogs (Rana sylvatica LeConte) are the major model for studies of natural freeze tolerance by ectothermic vertebrates. Multiple biochemical adaptations support winter freezing survival but, to date, the protective role of chaperone proteins has received little attention. The present study analyzes responses to freezing, anoxia or dehydration exposures and recovery from these stresses by chaperone proteins in six wood frog organs: Five heat shock proteins (Hsc70, Hsp110, Hsp60, Hsp40, and Hsp10) and two glucose-regulated proteins (Grp78 and Grp94) were assessed. Hsc70 was upregulated in liver, muscle, heart and kidney (1.5-2.0 fold) during freezing and levels of its partner proteins also rose (Hsp110 in three tissues and Hsp40 in four tissues), these responses aligning most closely with comparable responses to anoxia rather than to dehydration. The resident chaperones of the endoplasmic reticulum (Grp78 and Grp94) also rose during freezing in liver and muscle (1.4-1.8 fold) but were suppressed in heart and skin, patterns that generally differed from responses to anoxia or dehydration. Elevated GRPs in liver may support the production and secretion of novel freeze responsive proteins. Increased levels of mitochondrial Hsp60 and Hsp10 (1.5-2.2 fold) occurred in most tissues during freezing and generally mimicked responses to anoxia. Overall, this study indicates that increased levels of chaperone proteins resident in multiple subcellular compartments contribute to stabilizing the cellular proteome during whole body freezing of wood frogs. These responses are probably derived from pre-existing amphibian defenses for stabilizing the proteome under environmental low oxygen or dehydration stresses.
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Affiliation(s)
- Janet M Storey
- Department of Biology, Carleton University, Ottawa, Canada
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10
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Nguyen VC, Deck CA, Pamenter ME. Naked mole rats reduce the expression of ATP-dependent but not ATP-independent heat shock proteins in acute hypoxia. J Exp Biol 2019; 222:jeb.211243. [DOI: 10.1242/jeb.211243] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 10/18/2019] [Indexed: 01/02/2023]
Abstract
Naked mole rats (NMRs) are one of the most hypoxia-tolerant mammals identified and putatively experience intermittent and severe hypoxia in their underground burrows. Systemic physiological adaptions to hypoxia have begun to be investigated in this species; however, the cellular adaptations that underlie this tolerance remain poorly understood. Hypoxia compromises cellular energy production; and the maintenance of protein integrity when ATP generation is limited poses a major challenge. Heat shock proteins (HSPs) are cellular chaperones that are cytoprotective during hypoxia and we hypothesized that their expression would increase during acute hypoxia in NMRs. To test this hypothesis, we used qPCR and Western blot approaches to measure changes in gene and protein expression, respectively, of HSP27, HSP40, HSP70, and HSP90 in the brain, heart, liver, and temporalis muscle from NMRs following exposure to normoxia (21% O2) or hypoxia (7% O2 for 4, 12, or 24 hrs). Contrary to our expectations, we observed significant global reductions of ATP-dependant HSP70 and HSP90 (83% and 78%, respectively) after 24 hrs of hypoxia. Conversely, the expression of ATP-independent HSP27 and HSP40 proteins remained constant throughout the 24-hr hypoxic treatment in brain, heart and muscle. However, with prolonged hypoxia (24 hrs), the expression of HSP27 and HSP40 genes in these tissues was also reduced, suggesting that the protein expression of these chaperones may also eventually decrease in hypoxia. These results suggest that energy conservation is prioritized over cytoprotective protein chaperoning in NMR tissues during acute hypoxia. This unique adaptation may help NMRs to minimize energy expenditure while still maintaining proteostasis in hypoxia.
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Affiliation(s)
- Vu Chau Nguyen
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Courtney A. Deck
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
- North Carolina State University, Raleigh, North Carolina, USA
| | - Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
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11
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Miles AR, Hawrysh PJ, Hossein-Javaheri N, Buck LT. Taurine activates glycine and GABA A receptor currents in anoxia-tolerant painted turtle pyramidal neurons. ACTA ACUST UNITED AC 2018; 221:jeb.181529. [PMID: 30237241 DOI: 10.1242/jeb.181529] [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: 03/26/2018] [Accepted: 09/13/2018] [Indexed: 11/20/2022]
Abstract
Unlike anoxia-intolerant mammals, painted turtles can survive extended periods without oxygen. This is partly accomplished by an anoxia-mediated increase in gamma-aminobutyric acid (GABA) release, which activates GABA receptors and mediates spike arrest in turtle neurons via shunting inhibition. Extracellular taurine levels also increase during anoxia; why this occurs is unknown but it is speculated that glycine and/or GABAA/B receptors are involved. Given the general importance of inhibitory neurotransmission in the anoxia-tolerant painted turtle brain, we investigated the function of taurine as an inhibitory neuromodulator in turtle pyramidal neurons. Using whole-cell patch-clamp electrophysiological methods to record from neurons within a cortical brain sheet, we found that taurine depolarized membrane potential by ∼8 mV, increased whole-cell conductance ∼2-fold, and induced an inward current that possessed characteristics similar to GABA- and glycine-evoked currents. These effects were mitigated following glycine receptor antagonism with strychnine and GABAA receptor antagonism with gabazine, bicuculine or picrotoxin, but were unchanged following GABAB or glutamatergic receptor inhibition. These data indicate that a high concentration of taurine in vitro mediates its effects through both glycine and GABAA receptors, and suggests that taurine, in addition to GABA, inhibits neuronal activity during anoxia in the turtle cortex.
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Affiliation(s)
- Ashley R Miles
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3G5
| | - Peter J Hawrysh
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3G5
| | | | - Leslie T Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3G5 .,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada, M5S 3G5
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12
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Hadj-Moussa H, Storey KB. Micromanaging freeze tolerance: the biogenesis and regulation of neuroprotective microRNAs in frozen brains. Cell Mol Life Sci 2018; 75:3635-3647. [PMID: 29681008 PMCID: PMC11105625 DOI: 10.1007/s00018-018-2821-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/08/2018] [Accepted: 04/17/2018] [Indexed: 12/21/2022]
Abstract
When temperatures plummet below 0 °C, wood frogs (Rana sylvatica) can endure the freezing of up to ~ 65% of their body water in extracellular ice masses, displaying no measurable brain activity, no breathing, no movement, and a flat-lined heart. To aid survival, frogs retreat into a state of suspended animation characterized by global suppression of metabolic functions and reprioritization of energy usage to essential survival processes that is elicited, in part, by the regulatory controls of microRNAs. The present study is the first to investigate miRNA biogenesis and regulation in the brain of a freeze tolerant vertebrate. Indeed, proper brain function and adaptations to environmental stimuli play a crucial role in coordinating stress responses. Immunoblotting of miRNA biogenesis factors illustrated an overall reduction in the majority of these processing proteins suggesting a potential suppression of miRNA maturation over the freeze-thaw cycle. This was coupled with a large-scale RT-qPCR analysis of relative expression levels of 113 microRNA species in the brains of control, 24 h frozen, and 8 h thawed R. sylvatica. Of the 41 microRNAs differentially regulated during freezing and thawing, only two were significantly upregulated. Bioinformatic target enrichment of the downregulated miRNAs, performed at the low temperatures experienced during freezing and thawing, predicted their involvement in the potential activation of various neuroprotective processes such as synaptic signaling, intracellular signal transduction, and anoxia/ischemia injury protection. The predominantly downregulated microRNA fingerprint identified herein suggests a microRNA-mediated cryoprotective mechanism responsible for maintaining neuronal functions and facilitating successful whole brain freezing and thawing.
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Affiliation(s)
- Hanane Hadj-Moussa
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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Kıvrak EG, Yurt KK, Kaplan AA, Alkan I, Altun G. Effects of electromagnetic fields exposure on the antioxidant defense system. J Microsc Ultrastruct 2017; 5:167-176. [PMID: 30023251 PMCID: PMC6025786 DOI: 10.1016/j.jmau.2017.07.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/19/2017] [Accepted: 07/26/2017] [Indexed: 11/28/2022] Open
Abstract
Technological devices have become essential components of daily life. However, their deleterious effects on the body, particularly on the nervous system, are well known. Electromagnetic fields (EMF) have various chemical effects, including causing deterioration in large molecules in cells and imbalance in ionic equilibrium. Despite being essential for life, oxygen molecules can lead to the generation of hazardous by-products, known as reactive oxygen species (ROS), during biological reactions. These reactive oxygen species can damage cellular components such as proteins, lipids and DNA. Antioxidant defense systems exist in order to keep free radical formation under control and to prevent their harmful effects on the biological system. Free radical formation can take place in various ways, including ultraviolet light, drugs, lipid oxidation, immunological reactions, radiation, stress, smoking, alcohol and biochemical redox reactions. Oxidative stress occurs if the antioxidant defense system is unable to prevent the harmful effects of free radicals. Several studies have reported that exposure to EMF results in oxidative stress in many tissues of the body. Exposure to EMF is known to increase free radical concentrations and traceability and can affect the radical couple recombination. The purpose of this review was to highlight the impact of oxidative stress on antioxidant systems. Abbreviations: EMF, electromagnetic fields; RF, radiofrequency; ROS, reactive oxygen species; GSH, glutathione; GPx, glutathione peroxidase; GR, glutathione reductase; GST, glutathione S-transferase; CAT, catalase; SOD, superoxide dismutase; HSP, heat shock protein; EMF/RFR, electromagnetic frequency and radiofrequency exposures; ELF-EMFs, exposure to extremely low frequency; MEL, melatonin; FA, folic acid; MDA, malondialdehyde.
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Affiliation(s)
- Elfide Gizem Kıvrak
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Kıymet Kübra Yurt
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Arife Ahsen Kaplan
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Işınsu Alkan
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Gamze Altun
- Department of Histology and Embryology, Faculty of Medicine, Ondokuz Mayıs University, Samsun, Turkey
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Abstract
Freeze tolerance is an amazing winter survival strategy used by various amphibians and reptiles living in seasonally cold environments. These animals may spend weeks or months with up to ∼65% of their total body water frozen as extracellular ice and no physiological vital signs, and yet after thawing they return to normal life within a few hours. Two main principles of animal freeze tolerance have received much attention: the production of high concentrations of organic osmolytes (glucose, glycerol, urea among amphibians) that protect the intracellular environment, and the control of ice within the body (the first putative ice-binding protein in a frog was recently identified), but many other strategies of biochemical adaptation also contribute to freezing survival. Discussed herein are recent advances in our understanding of amphibian and reptile freeze tolerance with a focus on cell preservation strategies (chaperones, antioxidants, damage defense mechanisms), membrane transporters for water and cryoprotectants, energy metabolism, gene/protein adaptations, and the regulatory control of freeze-responsive hypometabolism at multiple levels (epigenetic regulation of DNA, microRNA action, cell signaling and transcription factor regulation, cell cycle control, and anti-apoptosis). All are providing a much more complete picture of life in the frozen state.
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Affiliation(s)
| | - Janet M. Storey
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
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15
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Liu Y, Wang XC, Hu D, Huang SR, Li QS, Li Z, Qu Y. Heat shock protein 70 protects PC12 cells against ischemia-hypoxia/reoxygenation by maintaining intracellular Ca(2+) homeostasis. Neural Regen Res 2016; 11:1134-40. [PMID: 27630698 PMCID: PMC4994457 DOI: 10.4103/1673-5374.187051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Heat shock protein 70 (HSP70) maintains Ca2+ homeostasis in PC12 cells, which may protect against apoptosis; however, the mechanisms of neuroprotection are unclear. Therefore, in this study, we examined Ca2+ levels in PC12 cells transfected with an exogenous lentiviral HSP70 gene expression construct, and we subsequently subjected the cells to ischemia-hypoxia/reoxygenation injury. HSP70 overexpression increased neuronal viability and ATPase activity, and it decreased cellular reactive oxygen species levels and intracellular Ca2+ concentration after hypoxia/reoxygenation. HSP70 overexpression enhanced the protein and mRNA expression levels of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA), but it decreased the protein and mRNA levels of inositol 1,4,5-trisphosphate receptor (IP3R), thereby leading to decreased intracellular Ca2+ concentration after ischemia-hypoxia/reoxygenation. These results suggest that exogenous HSP70 protects against ischemia-hypoxia/reoxygenation injury, at least in part, by maintaining cellular Ca2+ homeostasis, by upregulating SERCA expression and by downregulating IP3R expression.
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Affiliation(s)
- Yuan Liu
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Xue-Chun Wang
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Dan Hu
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Shu-Ran Huang
- Department of Intensive Care Unit, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, China
| | - Qing-Shu Li
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Zhi Li
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Yan Qu
- Department of Intensive Care Unit, Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, Shandong Province, China
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16
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Keenan SW, Hill CA, Kandoth C, Buck LT, Warren DE. Transcriptomic Responses of the Heart and Brain to Anoxia in the Western Painted Turtle. PLoS One 2015; 10:e0131669. [PMID: 26147940 PMCID: PMC4493013 DOI: 10.1371/journal.pone.0131669] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/05/2015] [Indexed: 12/23/2022] Open
Abstract
Painted turtles are the most anoxia-tolerant tetrapods known, capable of surviving without oxygen for more than four months at 3°C and 30 hours at 20°C. To investigate the transcriptomic basis of this ability, we used RNA-seq to quantify mRNA expression in the painted turtle ventricle and telencephalon after 24 hours of anoxia at 19°C. Reads were obtained from 22,174 different genes, 13,236 of which were compared statistically between treatments for each tissue. Total tissue RNA contents decreased by 16% in telencephalon and 53% in ventricle. The telencephalon and ventricle showed ≥ 2x expression (increased expression) in 19 and 23 genes, respectively, while only four genes in ventricle showed ≤ 0.5x changes (decreased expression). When treatment effects were compared between anoxic and normoxic conditions in the two tissue types, 31 genes were increased (≥ 2x change) and 2 were decreased (≤ 0.5x change). Most of the effected genes were immediate early genes and transcription factors that regulate cellular growth and development; changes that would seem to promote transcriptional, translational, and metabolic arrest. No genes related to ion channels, synaptic transmission, cardiac contractility or excitation-contraction coupling changed. The generalized expression pattern in telencephalon and across tissues, but not in ventricle, correlated with the predicted metabolic cost of transcription, with the shortest genes and those with the fewest exons showing the largest increases in expression.
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Affiliation(s)
- Sarah W. Keenan
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Craig A. Hill
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
| | - Cyriac Kandoth
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Leslie T. Buck
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Daniel E. Warren
- Department of Biology, Saint Louis University, St. Louis, Missouri, United States of America
- * E-mail:
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17
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Turtle anoxia tolerance: Biochemistry and gene regulation. Biochim Biophys Acta Gen Subj 2015; 1850:1188-96. [DOI: 10.1016/j.bbagen.2015.02.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 02/01/2015] [Indexed: 12/16/2022]
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18
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Misa-Agustiño M, Leiro-Vidal J, Gomez-Amoza J, Jorge-Mora M, Jorge-Barreiro F, Salas-Sánchez A, Ares-Pena F, López-Martín E. EMF radiation at 2450MHz triggers changes in the morphology and expression of heat shock proteins and glucocorticoid receptors in rat thymus. Life Sci 2015; 127:1-11. [DOI: 10.1016/j.lfs.2015.01.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 12/29/2014] [Accepted: 01/23/2015] [Indexed: 01/12/2023]
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19
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Smith RW, Cash P, Hogg DW, Buck LT. Proteomic changes in the brain of the western painted turtle (Chrysemys picta bellii) during exposure to anoxia. Proteomics 2015; 15:1587-97. [PMID: 25583675 DOI: 10.1002/pmic.201300229] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 10/03/2014] [Accepted: 01/09/2015] [Indexed: 01/10/2023]
Abstract
During anoxia, overall protein synthesis is almost undetectable in the brain of the western painted turtle. The aim of this investigation was to address the question of whether there are alterations to specific proteins by comparing the normoxic and anoxic brain proteomes. Reductions in creatine kinase, hexokinase, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase reflected the reduced production of adenosine triphosphate (ATP) during anoxia while the reduction in transitional endoplasmic reticulum ATPase reflected the conservation of ATP or possibly a decrease in intracellular Ca(2+). In terms of neural protection programed cell death 6 interacting protein (PDCD6IP; a protein associated with apoptosis), dihydropyrimidinase-like protein, t-complex protein, and guanine nucleotide protein G(o) subunit alpha (Go alpha; proteins associated with neural degradation and impaired cognitive function) also declined. A decline in actin, gelsolin, and PDCD6IP, together with an increase in tubulin, also provided evidence for the induction of a neurological repair response. Although these proteomic alterations show some similarities with the crucian carp (another anoxia-tolerant species), there are species-specific responses, which supports the theory of no single strategy for anoxia tolerance. These findings also suggest the anoxic turtle brain could be an etiological model for investigating mammalian hypoxic damage and clinical neurological disorders.
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Affiliation(s)
- Richard W Smith
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada
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20
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Tedeschi J, Kennington W, Berry O, Whiting S, Meekan M, Mitchell N. Increased expression of Hsp70 and Hsp90 mRNA as biomarkers of thermal stress in loggerhead turtle embryos (Caretta Caretta). J Therm Biol 2015; 47:42-50. [DOI: 10.1016/j.jtherbio.2014.11.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/12/2014] [Accepted: 11/15/2014] [Indexed: 12/18/2022]
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21
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Kocha KM, Reilly K, Porplycia DSM, McDonald J, Snider T, Moyes CD. Evolution of the oxygen sensitivity of cytochrome c oxidase subunit 4. Am J Physiol Regul Integr Comp Physiol 2014; 308:R305-20. [PMID: 25519729 DOI: 10.1152/ajpregu.00281.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Vertebrates possess two paralogs of cytochrome c oxidase (COX) subunit 4: a ubiquitous COX4-1 and a hypoxia-linked COX4-2. Mammalian COX4-2 is thought to have a role in relation to fine-tuning metabolism in low oxygen levels, conferred through both structural differences in the subunit protein structure and regulatory differences in the gene. We sought to elucidate the pervasiveness of this feature across vertebrates. The ratio of COX4-2/4-1 mRNA is generally low in mammals, but this ratio was higher in fish and reptiles, particularly turtles. The COX4-2 gene appeared unresponsive to low oxygen in nonmammalian models (zebrafish, goldfish, tilapia, anoles, and turtles) and fish cell lines. Reporter genes constructed from the amphibian and reptile homologues of the mammalian oxygen-responsive elements and hypoxia-responsive elements did not respond to low oxygen. Unlike the rodent ortholog, the promoter of goldfish COX4-2 did not respond to hypoxia or anoxia. The protein sequences of the COX4-2 peptide showed that the disulfide bridge seen in human and rodent orthologs would be precluded in other mammalian lineages and lower vertebrates, all of which lack the requisite pair of cysteines. The coordinating ligands of the ATP-binding site are largely conserved across mammals and reptiles, but in Xenopus and fish, sequence variations may disrupt the ability of the protein to bind ATP at this site. Collectively, these results suggest that many of the genetic and structural features of COX4-2 that impart responsiveness and benefits in hypoxia may be restricted to the Euarchontoglires lineage that includes primates, lagomorphs, and rodents.
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Affiliation(s)
- K M Kocha
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - K Reilly
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - D S M Porplycia
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - J McDonald
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - T Snider
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | - C D Moyes
- Department of Biology, Queen's University, Kingston, Ontario, Canada
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22
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Abstract
Decreased oxygen availability impairs cellular energy production and, without a coordinated and matched decrease in energy consumption, cellular and whole organism death rapidly ensues. Of particular interest are mechanisms that protect brain from low oxygen injury, as this organ is not only the most sensitive to hypoxia, but must also remain active and functional during low oxygen stress. As a result of natural selective pressures, some species have evolved molecular and physiological mechanisms to tolerate prolonged hypoxia with no apparent detriment. Among these mechanisms are a handful of responses that are essential for hypoxia tolerance, including (i) sensors that detect changes in oxygen availability and initiate protective responses; (ii) mechanisms of energy conservation; (iii) maintenance of basic brain function; and (iv) avoidance of catastrophic cell death cascades. As the study of hypoxia-tolerant brain progresses, it is becoming increasingly apparent that mitochondria play a central role in regulating all of these critical mechanisms. Furthermore, modulation of mitochondrial function to mimic endogenous neuroprotective mechanisms found in hypoxia-tolerant species confers protection against otherwise lethal hypoxic stresses in hypoxia-intolerant organs and organisms. Therefore, lessons gleaned from the investigation of endogenous mechanisms of hypoxia tolerance in hypoxia-tolerant organisms may provide insight into clinical pathologies related to low oxygen stress.
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Affiliation(s)
- Matthew E. Pamenter
- Department of Zoology, The University of British Columbia, #4200-6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
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23
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Madeira D, Narciso L, Diniz MS, Vinagre C. Synergy of environmental variables alters the thermal window and heat shock response: an experimental test with the crab Pachygrapsus marmoratus. MARINE ENVIRONMENTAL RESEARCH 2014; 98:21-28. [PMID: 24836643 DOI: 10.1016/j.marenvres.2014.03.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/12/2014] [Accepted: 03/17/2014] [Indexed: 06/03/2023]
Abstract
The intertidal zone is an extremely variable habitat, imposing stressful conditions on its inhabiting communities. Tolerance towards extremes of temperature, salinity and pH are crucial in these habitats. Despite the vast literature on stress tolerance, few studies have focused on the synergistic effects of several variables on thermal tolerance and HSP70 (heat shock protein 70 kDa) levels. In this work, the crabs were exposed to three experimental conditions 1) thermal ramp at standard pH (8) and saline conditions (35‰) (named T), 2) thermal ramp at standard pH (8) and hyposaline conditions (15‰) (named T plus HypoS), and 3) thermal ramp at lower pH (7) and standard saline conditions (35‰) (named T plus A). Two physiological parameters (Critical Thermal Maximum - CTMax, and osmolality) and a stress biomarker (HSP70) were chosen for this analysis. These parameters were measured in all of the aforementioned conditions. CTMax for each set of conditions was reached by exposing the organisms to a rate of temperature increase of 1 °C h(-1) until loss of equilibrium. Haemolymph samples were taken every 2 °C to quantify HSP70 and osmolality. Results showed that CTMax did not differ between crabs solely exposed to T stress and crabs exposed to T plus HypoS stress. However, HSP70 production was impaired in T plus HypoS stress. When crabs were exposed to T plus A stress, they showed a significantly higher CTMax, suggesting that short-term exposure to acidified conditions may alter the thermal window of this species. Nevertheless, in T plus A conditions HSP70 production was impaired as well. Regarding osmolality it decreased according to temperature increase in all tested stress conditions. This study showed that the heat stress response is altered by the synergistic effect of variables. Physiological end-points (i.e. CTMax) may vary and the expression of stress proteins such as HSP70 may be impaired.
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Affiliation(s)
- Diana Madeira
- Centro de Oceanografia, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal; REQUIMTE, Departamento de Química, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Luís Narciso
- Laboratório Marítimo da Guia, Centro de Oceanografia, Faculdade de Ciências, Universidade de Lisboa, 2750-374 Cascais, Portugal
| | - Mário Sousa Diniz
- REQUIMTE, Departamento de Química, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
| | - Catarina Vinagre
- Centro de Oceanografia, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
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24
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Polymeropoulos ET, Plouffe D, LeBlanc S, Elliott NG, Currie S, Frappell PB. Growth hormone transgenesis and polyploidy increase metabolic rate, alter the cardiorespiratory response and influence HSP expression in response to acute hypoxia in Atlantic salmon (Salmo salar) yolk-sac alevins. ACTA ACUST UNITED AC 2014; 217:2268-76. [PMID: 24675560 DOI: 10.1242/jeb.098913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Growth hormone (GH)-transgenic Atlantic salmon display accelerated growth rates compared with non-transgenics. GH-transgenic fish also display cardiorespiratory and metabolic modifications that accompany the increased growth rate. An elevated routine metabolic rate has been described for pre- and post-smolt GH-transgenic salmon that also display improvements in oxygen delivery to support the increased aerobic demand. The early ontogenic effects of GH transgenesis on the respiratory and cellular physiology of fish, especially during adverse environmental conditions, and the effect of polyploidy are unclear. Here, we investigated the effects of GH transgenesis and polyploidy on metabolic, heart and ventilation rates and heat shock protein (HSP) levels after exposure to acute hypoxia in post-hatch Atlantic salmon yolk-sac alevins. Metabolic rate decreased with decreasing partial pressures of oxygen in all genotypes. In normoxia, triploid transgenics displayed the highest mass-specific metabolic rates in comparison to diploid transgenics and non-transgenic triploids, which, in contrast, had higher rates than diploid non-transgenics. In hypoxia, we observed a lower mass-specific metabolic rate in diploid non-transgenics compared with all other genotypes. However, no evidence for improved O2 uptake through heart or ventilation rate was found. Heart rate decreased in diploid non-transgenics while ventilation rate decreased in both diploid non-transgenics and triploid transgenics in severe hypoxia. Regardless of genotype or treatment, inducible HSP70 was not expressed in alevins. Following hypoxia, the constitutive isoform of HSP70, HSC70, decreased in transgenics and HSP90 expression decreased in all genotypes. These data suggest that physiological changes through GH transgenesis and polyploidy are manifested during early ontogeny in Atlantic salmon.
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Affiliation(s)
- Elias T Polymeropoulos
- CSIRO National Food Futures Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, TAS 7001, Australia
| | | | - Sacha LeBlanc
- Department of Biology, Mount Allison University, Sackville, NB, Canada E4L 1G7
| | - Nick G Elliott
- CSIRO National Food Futures Flagship, CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, TAS 7001, Australia
| | - Suzie Currie
- Department of Biology, Mount Allison University, Sackville, NB, Canada E4L 1G7
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Takeshita S, Matsuda N, Kodama S, Suzuki K, Watanabe M. In Vitro Thermal Effects on Embryonic Cells of Endangered Hawksbill TurtleEretmochelys imbricata. Zoolog Sci 2013; 30:1038-43. [DOI: 10.2108/zsj.30.1038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Hu D, Chen F, Guan C, Yang F, Qu Y. Anti-hypoxia effect of adenovirus-mediated expression of heat shock protein 70 (HSP70) on primary cultured neurons. J Neurosci Res 2013; 91:1174-82. [PMID: 23686726 DOI: 10.1002/jnr.23240] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 03/04/2013] [Accepted: 03/27/2013] [Indexed: 12/21/2022]
Abstract
Heat shock protein 70 (HSP70) has attracted great attention recently in hypoxia injury because of its close link to the recovery after hypoxic-ischemic damage in organs. However, the cellular mechanism underlying its protective roles remains unclear. In this study, we developed a recombinant adenovirus containing HSP70-GFP (vAd-HSP70-GFP) and studied the effect of virus-mediated expression of exogenous HSP70 gene on neurons in response to hypoxia-reoxygenation injury. Virus-mediated expression of HSP70 was detected as early as 24 hr and lasted until 10 days after infection. Neurons with 48 hr vAd-HSP70-GFP infection were exposed to 0, 0.5, 1, 2, 3, or 4 hr hypoxia followed by 1 hr reoxygenation. The mRNA and protein levels of HSP70 in neurons exposed to different lengths of hypoxia were compared by using RT-PCR and Western blotting (WB). The 1-hr hypoxia exposure showed the most significant increases in the HSP70 mRNA and protein level compared with other exposure durations. MTT assay showed that HSP70 overexpression significantly increased the neuronal viability, accompanied by decreased lactate dehydrogenase (LDH) activity in the culture medium after hypoxia-reoxygenation. Neurons with vAd-HSP70-GFP exhibited increased levels of mitochondrial cytochrome C (Cyt-C) and decreased levels of cytoplasmic Cyt-C compared with vAd-GFP-infected cells. These results suggest a neuroprotective role of exogenous HSP70 against hypoxia-reoxygenation injury, possibly via preventing initiation of mitochondrial apoptosis.
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Affiliation(s)
- Dan Hu
- Department of Intensive Care Unit, Municipal Hospital of Medical College of Qingdao University, Qingdao, China
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27
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Misa Agustiño MJ, Leiro JM, Jorge Mora MT, Rodríguez-González JA, Jorge Barreiro FJ, Ares-Pena FJ, López-Martín E. Electromagnetic fields at 2.45 GHz trigger changes in heat shock proteins 90 and 70 without altering apoptotic activity in rat thyroid gland. Biol Open 2012; 1:831-8. [PMID: 23213477 PMCID: PMC3507243 DOI: 10.1242/bio.20121297] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 06/07/2012] [Indexed: 12/17/2022] Open
Abstract
Non-ionizing radiation at 2.45 GHz may modify the expression of genes that codify heat shock proteins (HSP) in the thyroid gland. Using the enzyme-linked immunosorbent assay (ELISA) technique, we studied levels of HSP-90 and HSP-70. We also used hematoxilin eosin to look for evidence of lesions in the gland and applied the DAPI technique of fluorescence to search for evidence of chromatin condensation and nuclear fragmentation in the thyroid cells of adult female Sprague-Dawley rats. Fifty-four rats were individually exposed for 30 min to 2.45 GHz radiation in a Gigahertz transverse electromagnetic (GTEM) cell at different levels of non-thermal specific absorption rate (SAR), which was calculated using the finite difference time domain (FDTD) technique. Ninety minutes after radiation, HSP-90 and HSP-70 had decreased significantly (P<0.01) after applying a SAR of 0.046±1.10 W/Kg or 0.104±5.10−3 W/Kg. Twenty-four hours after radiation, HSP-90 had partially recovered and HSP-70 had recovered completely. There were few indications of lesions in the glandular structure and signs of apoptosis were negative in all radiated animals. The results suggest that acute sub-thermal radiation at 2.45 GHz may alter levels of cellular stress in rat thyroid gland without initially altering their anti-apoptotic capacity.
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Stecyk JAW, Couturier CS, Fagernes CE, Ellefsen S, Nilsson GE. Quantification of heat shock protein mRNA expression in warm and cold anoxic turtles (Trachemys scripta) using an external RNA control for normalization. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2011; 7:59-72. [PMID: 22129782 DOI: 10.1016/j.cbd.2011.11.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 11/07/2011] [Accepted: 11/07/2011] [Indexed: 01/30/2023]
Abstract
The mRNA expression of heat-shock protein 90 (HSP90) and heat-shock cognate 70 (HSC70) was examined in cardiac chambers and telencephalon of warm- (21°C) and cold-acclimated (5°C) turtles (Trachemys scripta) exposed to normoxia, prolonged anoxia or anoxia followed by reoxygenation. Additionally, the suitability of total RNA as well as mRNA from β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and cyclophilin A (PPIA) for normalizing gene expression data was assessed, as compared to the use of an external RNA control. Measurements of HSP90 and HSC70 mRNA expression revealed that anoxia and reoxygenation have tissue- and gene-specific effects. By and large, the alterations support previous investigations on HSP protein abundance in the anoxic turtle heart and brain, as well as the hypothesized roles of HSP90 and HSC70 during stress and non-stress conditions. However, more prominent was a substantially increased HSP90 and HSC70 mRNA expression in the cardiac chambers with cold acclimation. The finding provides support for the notion that cold temperature induces a number of adaptations in tissues of anoxia-tolerant vertebrates that precondition them for winter anoxia. β-actin, GAPDH and PPIA mRNA expression and total RNA also varied with oxygenation state and acclimation temperature in a tissue- and gene-specific manner, as well as among tissue types, thus disqualifying them as suitable for real-time RT-PCR normalization. Thus, the present data highlights the advantages of normalizing real-time RT-PCR data to an external RNA control, an approach that also allows inter-tissue and potentially inter-species comparisons of target gene expression.
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Affiliation(s)
- Jonathan A W Stecyk
- Physiology Programme, Department of Molecular Biosciences, University of Oslo, PO Box 1041, N-0316, Oslo, Norway.
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Michaud MR, Teets NM, Peyton JT, Blobner BM, Denlinger DL. Heat shock response to hypoxia and its attenuation during recovery in the flesh fly, Sarcophaga crassipalpis. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:203-210. [PMID: 21075112 DOI: 10.1016/j.jinsphys.2010.11.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 11/04/2010] [Accepted: 11/05/2010] [Indexed: 05/30/2023]
Abstract
In this study, pharate adults of the flesh fly Sarcophaga crassipalpis were exposed to two, four, seven, or ten days of severe hypoxia (3% oxygen) to evaluate its impact on emergence and the expression of genes encoding heat shock proteins (Hsps) and heat shock regulatory elements. A four-day exposure to hypoxia significantly reduced survival, but more than seven days was required to reach the LD(50). Eight genes encoding Hsps, at least one from each major family of Hsps (Hsp90, Hsp70, Hsp60, Hsp40, and sHsps) and two genes encoding proteins involved in Hsp regulation (heat shock factor, hsf, and sirtuin) were cloned, and expression levels were assessed during and after hypoxia using qRT-PCR. Most, but not all hsps studied, were significantly up-regulated during hypoxia, and expression levels for most of the hsps reverted to control levels a few hours after return to normoxia. Hsp70 was the most responsive to hypoxia, increasing expression several hundred fold. By contrast, hsp90 and hsp27 showed little response to hypoxia but did respond to recovery. Neither hsf nor sirtuin were elevated by hypoxia, an observation consistent with their assumed post-transcriptional regulatory roles. These data demonstrate a strong Hsp response to hypoxia, suggesting an important role for Hsps in responding to low oxygen environments.
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Affiliation(s)
- M Robert Michaud
- Department of Entomology, The Ohio State University, 318 W. 12th Ave., Columbus, OH 43210, USA
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30
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Prentice HM. Decreased temperature as a signal for regulation of heat shock protein expression in anoxic brain and heart: focus on “Expression of heat shock proteins in anoxic crucian carp (Carassius carassius): support for cold as a preparatory cue for anoxia”. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1496-8. [DOI: 10.1152/ajpregu.00237.2010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Howard M. Prentice
- College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida
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31
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Stensløkken KO, Ellefsen S, Larsen HK, Vaage J, Nilsson GE. Expression of heat shock proteins in anoxic crucian carp (Carassius carassius): support for cold as a preparatory cue for anoxia. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1499-508. [DOI: 10.1152/ajpregu.00675.2009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The crucian carp ( Carassius carassius ) tolerates anoxia for days to months depending on temperature. During episodes of stress, heat shock proteins (HSPs) are important for limiting cellular damage, mainly by ensuring protein function. Accordingly, we hypothesized that anoxia would change the expression of HSPs and that this response would be temperature dependent. Real-time RT-PCR was used to investigate the effects of 1 and 7 days anoxia (A1 and A7) on the expression of HSP70a, HSP70b, HSC70, HSP90, and HSP30 in the brain and heart of 8°C- and 13°C-acclimated crucian carp. In general, the expression of all HSPs changed in response to anoxia, although varying in size and direction, and with organ and temperature. HSP70a expression increased drastically (∼10-fold) in A7 brains and hearts at 13°C but not at 8°C. HSC70 and HSP90 expression decreased in A7 brains (by 60–70%), but not in A7 hearts. HSC70 expression increased in A1 brains and hearts at both temperatures (by 60–160%), and HSP30 expression decreased in A7 brains and hearts at both temperatures (by 50–80%). Notably, normoxic fish showed 7- and 11-fold higher HSP70a expression in the brain and heart at 8°C compared with 13°C. This difference disappeared during anoxia, suggesting that cold may function as a cue for preconditioning the crucian carp's HSP70a expression to the approaching anoxic winter period.
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Affiliation(s)
- Kåre-Olav Stensløkken
- Department of Molecular Biosciences and
- Faculty Division Ullevål University Hospital, University of Oslo, Oslo, Norway; and
| | | | | | - Jarle Vaage
- Faculty Division Ullevål University Hospital, University of Oslo, Oslo, Norway; and
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32
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Shen HY, Zhao Y, Chen XY, Xiong RP, Lu JL, Chen JF, Chen LY, Zhou YG. Differential alteration of heat shock protein 90 in mice modifies glucocorticoid receptor function and susceptibility to trauma. J Neurotrauma 2010; 27:373-81. [PMID: 19845467 DOI: 10.1089/neu.2009.0926] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heat shock protein 90 (Hsp90), encoded by the murine hsp84 and hsp86 genes in mice, is a pivotal regulator of glucocorticoid receptor (GR) function in the hypothalamus-pituitary-adrenal axis and affords stress protection. To explore the underlying molecular mechanisms of strain susceptibility to traumatic stress, we investigated the alteration by Hsp90 of the function of the glucocorticoid-glucocorticoid receptor (GC-GR) pathway in attenuating stress responses in C57BL/6 and BALB/c mice using the whole-body blast injury (WBBI) model. We found that C57BL/6 mice had a lower WBBI-induced mortality, higher nuclear GR level, and higher glucocorticoid-response element (GRE) binding activity than BALB/c mice. This study is the first report identifying four genetic variations of the murine hsp84 gene: 226A>C, 996G>C, 1483G>C, and 2000G>T. These nucleotide changes occur in the functional domains associated with the nuclear/cytosolic translocation of GR, GR-Hsp90 interaction, ATP binding, and self-dimerization of Hsp90, respectively. Further, we used a specific Hsp90 inhibitor, geldanamycin (GA), to assess the role of Hsp90 in the discriminative traumatic response in C57BL/6 mice. Pretreatment with GA reduced nuclear GR levels and GRE binding activity, and enhanced WBBI-induced mortality. These findings suggest that Hsp90 may underlie the strain-selective (C57BL/6 versus BALB/c) susceptibility to WBBI by mediating the nuclear translocation of GRs and GRE binding. Thus, pharmacological manipulation of Hsp90 may represent a therapeutic strategy to modify the function of the GC-GR pathway and traumatic stress response.
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Affiliation(s)
- Hai-Ying Shen
- Molecular Biology Center, State Key Laboratory of Trauma, Burn and Combined Injury, Third Military Medical University, Chongqing, PR China
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Jorge-Mora T, Alvarez Folgueiras M, Leiro J, Jorge-Barreiro FJ, Ares-Pena FJ, Lopez-Martin E. EXPOSURE TO 2.45 GHz MICROWAVE RADIATION PROVOKES CEREBRAL CHANGES IN INDUCTION OF HSP-90 α/β HEAT SHOCK PROTEIN IN RAT. ACTA ACUST UNITED AC 2010. [DOI: 10.2528/pier09102804] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Currie S, Bagatto B, DeMille M, Learner A, LeBlanc D, Marks C, Ong K, Parker J, Templeman N, Tufts BL, Wright PA. Metabolism, nitrogen excretion, and heat shock proteins in the central mudminnow (Umbra limi), a facultative air-breathing fish living in a variable environment. CAN J ZOOL 2010. [DOI: 10.1139/z09-117] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The central mudminnow ( Umbra limi (Kirtland, 1841)) is a continuous, facultative air-breathing freshwater fish found in swamps of central Canada and northeastern USA. The first goal of this field and laboratory-based study was to characterize the physicochemical conditions of mudminnow habitat during the summer. Our second goal was to determine the metabolic, stress response, and nitrogen excretion strategies of this fish following variations in water temperature, dissolved oxygen, external ammonia, and short-term periods of air exposure. We report profound diurnal fluctuations in water temperature (13–31 °C), dissolved oxygen (2%–159% air saturation), and ammonia levels (10–240 μmol·L−1) in habitat of central mudminnow measured on three dates at six different sites over 24 h. The central mudminnow does not induce urea synthesis as a mechanism of ammonia detoxification, either in response to emersion (6 or 20 h) or elevated external ammonia (10 mmol·L–1). Acute exposure to high temperature (~31 °C), aquatic hypoxia, or air resulted in significant increases in blood glucose and liver heat shock protein (Hsp) 70 and hypoxia also caused an increased reliance on anaerobic metabolism. This is the first description of the heat shock response in a facultative air-breathing fish following either hypoxia or air exposure. These metabolic and molecular responses are part of a strategy that allows the mudminnow to thrive in extremely variable freshwater environments.
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Affiliation(s)
- S. Currie
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - B. Bagatto
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - M. DeMille
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - A. Learner
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - D. LeBlanc
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - C. Marks
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - K. Ong
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - J. Parker
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - N. Templeman
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - B. L. Tufts
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - P. A. Wright
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Department of Biology, University of Akron, Akron, OH 44325, USA
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada
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35
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Krivoruchko A, Storey KB. Regulation of the heat shock response under anoxia in the turtle, Trachemys scripta elegans. J Comp Physiol B 2009; 180:403-14. [PMID: 19834715 DOI: 10.1007/s00360-009-0414-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 09/14/2009] [Accepted: 09/25/2009] [Indexed: 10/20/2022]
Abstract
The effects of 20 h of anoxic submergence in cold water and 5 h of aerobic recovery on the heat shock response were analyzed in four organs of the anoxia-tolerant turtle Trachemys scripta elegans. Immunoblotting was used to analyze levels of active and inactive forms of the heat shock transcription factor 1 (HSF1), nuclear translocation of HSF1, and the levels of six heat shock proteins (HSPs). PCR was also used to retrieve the turtle HSF1 nucleotide sequence; its deduced amino acid sequence showed 97% identity with chicken HSF1. White skeletal muscle showed a strong fivefold increase in the amount of active HSF1 under anoxic conditions as well as an 80% increase in nuclear localization. This was accompanied by upregulation of five HSPs by 1.8- to 2.9-fold: Hsp25, Hsp40, Hsp70, Hsc70, and Hsp90, the latter two remained elevated after 5 h of aerobic recovery. Kidney and liver showed little change in active HSF1 content during anoxia and recovery, but a significant increase in the nuclear localization of HSF1 during anoxia. This supported enhanced expression of three HSPs in kidney (Hsp40, Hsc70, and Hsp90) and four in liver (Hsp40, Hsp60, Hsp70, Hsc70). Heart displayed a strong increase in active HSF1 during anoxia and recovery (6.6- to 6.8-fold higher than control) and increased nuclear localization but heart HSP levels did not rise. The data demonstrate organ-specific regulation of HSPs during anoxia exposure and aerobic recovery in T. s. elegans and suggest that the heat shock response is an important aspect of cytoprotection during facultative anaerobiosis, particularly with regard to underwater hibernation of turtles in cold water.
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Affiliation(s)
- Anastasia Krivoruchko
- Department of Biology, Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
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36
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Specific proteins allow classification of pigs according to sire breed, rearing environment and gender. Livest Sci 2009. [DOI: 10.1016/j.livsci.2008.08.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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37
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Kesaraju S, Schmidt-Kastner R, Prentice HM, Milton SL. Modulation of stress proteins and apoptotic regulators in the anoxia tolerant turtle brain. J Neurochem 2009; 109:1413-26. [PMID: 19476552 DOI: 10.1111/j.1471-4159.2009.06068.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Freshwater turtles survive prolonged anoxia and reoxygenation without overt brain damage by well-described physiological processes, but little work has been done to investigate the molecular changes associated with anoxic survival. We examined stress proteins and apoptotic regulators in the turtle during early (1 h) and long-term anoxia (4, 24 h) and reoxygenation. Western blot analyses showed changes within the first hour of anoxia; multiple stress proteins (Hsp72, Grp94, Hsp60, Hsp27, and HO-1) increased while apoptotic regulators (Bcl-2 and Bax) decreased. Levels of the ER stress protein Grp78 were unchanged. Stress proteins remained elevated in long-term anoxia while the Bcl-2/Bax ratio was unaltered. No changes in cleaved caspase 3 levels were observed during anoxia while apoptosis inducing factor increased significantly. Furthermore, we found no evidence for the anoxic translocation of Bax from the cytosol to mitochondria, nor movement of apoptosis inducing factor between the mitochondria and nucleus. Reoxygenation did not lead to further increases in stress proteins or apoptotic regulators except for HO-1. The apparent protection against cell damage was corroborated with immunohistochemistry, which indicated no overt damage in the turtle brain subjected to anoxia and reoxygenation. The results suggest that molecular adaptations enhance pro-survival mechanisms and suppress apoptotic pathways to confer anoxia tolerance in freshwater turtles.
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Affiliation(s)
- Shailaja Kesaraju
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431, USA.
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38
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Regulation of global protein translation and protein degradation in aerobic dormancy. Mol Cell Biochem 2008; 323:9-20. [DOI: 10.1007/s11010-008-9959-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 10/28/2008] [Indexed: 11/26/2022]
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39
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Storey KB, Storey JM. Tribute to P. L. Lutz: putting life on 'pause'--molecular regulation of hypometabolism. ACTA ACUST UNITED AC 2008; 210:1700-14. [PMID: 17488933 DOI: 10.1242/jeb.02716] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Entry into a hypometabolic state is an important survival strategy for many organisms when challenged by environmental stress, including low oxygen, cold temperatures and lack of food or water. The molecular mechanisms that regulate transitions to and from hypometabolic states, and stabilize long-term viability during dormancy, are proving to be highly conserved across phylogenic lines. A number of these mechanisms were identified and explored using anoxia-tolerant turtles as the model system, particularly from the research contributions made by Dr Peter L. Lutz in his explorations of the mechanisms of neuronal suppression in anoxic brain. Here we review some recent advances in understanding the biochemical mechanisms of metabolic arrest with a focus on ideas such as the strategies used to reorganize metabolic priorities for ATP expenditure, molecular controls that suppress cell functions (e.g. ion pumping, transcription, translation, cell cycle arrest), changes in gene expression that support hypometabolism, and enhancement of defense mechanisms (e.g. antioxidants, chaperone proteins, protease inhibitors) that stabilize macromolecules and promote long-term viability in the hypometabolic state.
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Affiliation(s)
- Kenneth B Storey
- Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada.
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40
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Storey KB. Anoxia tolerance in turtles: Metabolic regulation and gene expression. Comp Biochem Physiol A Mol Integr Physiol 2007; 147:263-76. [PMID: 17035057 DOI: 10.1016/j.cbpa.2006.03.019] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2005] [Revised: 03/14/2006] [Accepted: 03/24/2006] [Indexed: 01/08/2023]
Abstract
Freshwater turtles of the Trachemys and Chrysemys genera are champion facultative anaerobes able to survive for several months without oxygen during winter hibernation in cold water. They have been widely used as models to identify and understand the molecular mechanisms of natural anoxia tolerance and the molecular basis of the hypoxic/ischemic injuries that occur in oxygen-sensitive systems and underlie medical problems such as heart attack and stroke. Peter L. Lutz spent much of his career investigating turtle anaerobiosis with a particular focus on the mechanisms of brain ion homeostasis and neurotransmitter responses to anoxia exposure and the mechanisms that suppress brain ion channel function and neuronal excitability during anaerobiosis. Our interests intersected over the mechanisms of metabolic rate depression which is key to long term anoxia survival. Studies in my lab have shown that a key mechanism of metabolic arrest is reversible protein phosphorylation which provides coordinated suppression of the rates of multiple ATP-producing, ATP-utilizing and related cellular processes to allow organisms to enter a stable hypometabolic state. Anoxia tolerance is also supported by selective gene expression as revealed by recent studies using cDNA library and DNA array screening. New studies with both adult T. scripta elegans and hatchling C. picta marginata have identified prominent groups of genes that are up-regulated under anoxia in turtle organs, in several cases suggesting aspects of cell function and metabolic regulation that have not previously been associated with anaerobiosis. These groups of anoxia-responsive genes include mitochondrially-encoded subunits of electron transport chain proteins, iron storage proteins, antioxidant enzymes, serine protease inhibitors, transmembrane solute carriers, neurotransmitter receptors and transporters, and shock proteins.
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Affiliation(s)
- Kenneth B Storey
- Institute of Biochemistry, College of Natural Sciences, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
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41
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Bickler PE, Buck LT. Hypoxia tolerance in reptiles, amphibians, and fishes: life with variable oxygen availability. Annu Rev Physiol 2007; 69:145-70. [PMID: 17037980 DOI: 10.1146/annurev.physiol.69.031905.162529] [Citation(s) in RCA: 423] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability of fishes, amphibians, and reptiles to survive extremes of oxygen availability derives from a core triad of adaptations: profound metabolic suppression, tolerance of ionic and pH disturbances, and mechanisms for avoiding free-radical injury during reoxygenation. For long-term anoxic survival, enhanced storage of glycogen in critical tissues is also necessary. The diversity of body morphologies and habitats and the utilization of dormancy have resulted in a broad array of adaptations to hypoxia in lower vertebrates. For example, the most anoxia-tolerant vertebrates, painted turtles and crucian carp, meet the challenge of variable oxygen in fundamentally different ways: Turtles undergo near-suspended animation, whereas carp remain active and responsive in the absence of oxygen. Although the mechanisms of survival in both of these cases include large stores of glycogen and drastically decreased metabolism, other mechanisms, such as regulation of ion channels in excitable membranes, are apparently divergent. Common themes in the regulatory adjustments to hypoxia involve control of metabolism and ion channel conductance by protein phosphorylation. Tolerance of decreased energy charge and accumulating anaerobic end products as well as enhanced antioxidant defenses and regenerative capacities are also key to hypoxia survival in lower vertebrates.
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Affiliation(s)
- Philip E Bickler
- Department of Anesthesia, University of California, San Francisco, California 94143, USA.
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42
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Pamenter ME, Richards MD, Buck LT. Anoxia-induced changes in reactive oxygen species and cyclic nucleotides in the painted turtle. J Comp Physiol B 2007; 177:473-81. [PMID: 17347830 DOI: 10.1007/s00360-007-0145-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 12/28/2006] [Accepted: 01/03/2007] [Indexed: 01/07/2023]
Abstract
The Western painted turtle survives months without oxygen. A key adaptation is a coordinated reduction of cellular ATP production and utilization that may be signaled by changes in the concentrations of reactive oxygen species (ROS) and cyclic nucleotides (cAMP and cGMP). Little is known about the involvement of cyclic nucleotides in the turtle's metabolic arrest and ROS have not been previously measured in any facultative anaerobes. The present study was designed to measure changes in these second messengers in the anoxic turtle. ROS were measured in isolated turtle brain sheets during a 40-min normoxic to anoxic transition. Changes in cAMP and cGMP were determined in turtle brain, pectoralis muscle, heart and liver throughout 4 h of forced submergence at 20-22 degrees C. Turtle brain ROS production decreased 25% within 10 min of cyanide or N(2)-induced anoxia and returned to control levels upon reoxygenation. Inhibition of electron transfer from ubiquinol to complex III caused a smaller decrease in [ROS]. Conversely, inhibition of complex I increased [ROS] 15% above controls. In brain [cAMP] decreased 63%. In liver [cAMP] doubled after 2 h of anoxia before returning to control levels with prolonged anoxia. Conversely, skeletal muscle and heart [cAMP] remained unchanged; however, skeletal muscle [cGMP] became elevated sixfold after 4 h of submergence. In liver and heart [cGMP] rose 41 and 127%, respectively, after 2 h of anoxia. Brain [cGMP] did not change significantly during 4 h of submergence. We conclude that turtle brain ROS production occurs primarily between mitochondrial complexes I and III and decreases during anoxia. Also, cyclic nucleotide concentrations change in a manner suggestive of a role in metabolic suppression in the brain and a role in increasing liver glycogenolysis.
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Affiliation(s)
- Matthew Edward Pamenter
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St., Toronto, ON, Canada M5S 3G5
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43
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Horowitz M. Heat acclimation and cross-tolerance against novel stressors: genomic–physiological linkage. PROGRESS IN BRAIN RESEARCH 2007; 162:373-92. [PMID: 17645928 DOI: 10.1016/s0079-6123(06)62018-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Heat acclimation (AC) is a "within lifetime" reversible phenotypic adaptation, enhancing thermotolerance and heat endurance via a transition to "efficient" cellular performance when acclimatory homeostasis is reached. An inseparable outcome of AC is the development of cross-tolerance (C-T) against novel stressors. This chapter focuses on central plasticity and the molecular-physiological linkage of acclimatory and C-T responses. A drop in temperature thresholds (T-Tsh) for activation of heat-dissipation mechanisms and an elevated T-Tsh for thermal injury development imply autonomic nervous system (ANS) and cytoprotective network involvement in these processes. During acclimation, the changes in T-Tsh for heat dissipation are biphasic. Initially T-Tsh drops, signifying the early autonomic response, and is associated with perturbed peripheral effector cellular performance. Pre-acclimation values return when acclimatory homeostasis is achieved. The changes in the ANS suggest that acclimatory plasticity involves molecular and cellular changes. These changes are manifested by the activation of central peripheral molecular networks and post-translational modifications. Sympathetic induction of elevated HSP 72 reservoirs, with faster heat shock response, is only one example of this. The global genomic response, detected using gene-chips and cluster analyses imply upregulation of genes encoding ion channels, pumps, and transporters (markers for neuronal excitability) in the hypothalamus at the onset of AC and down regulation of metabotrophic genes upon long term AC. Peripherally, the transcriptional program indicates a two-tier defense strategy. The immediate transient response is associated with the maintenance of DNA and cellular integrity. The sustained response correlates with long-lasting cytoprotective-signaling networks. C-T is recorded against cerebral hypoxia, hyperoxia, and traumatic brain injury. Using the highly developed ischemic/reperfused heart model as a baseline, it is evident that C-T stems via protective shared pathways developed with AC. These comprise constitutive elevation of HIF 1alpha and associated target pathways, HSPs, anti-apoptosis, and antioxidative pathways. Collectively the master regulators of AC and C-T are still enigmatic; however, cutting-edge investigative techniques, using a broad molecular approach, challenge current ideas, and the data accumulated will pinpoint novel pathways and provide new perspectives.
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Affiliation(s)
- Michal Horowitz
- Laboratory of Environmental Physiology, The Hebrew University, POB 12272, Jerusalem 91120, Israel.
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44
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Kim SW, Hwang HJ, Cho EJ, Oh JY, Baek YM, Choi JW, Yun JW. Time-Dependent Plasma Protein Changes in Streptozotocin-Induced Diabetic Rats before and after Fungal Polysaccharide Treatments. J Proteome Res 2006; 5:2966-76. [PMID: 17081048 DOI: 10.1021/pr0602601] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Previous studies about protein modulation with chemically induced models of diabetes in animals have yielded conflicting results, in that many investigators have reported different regulation patterns for the same proteins. Therefore, it is reasonable to determine biomarkers for prognosis and diagnosis of diabetes with time profiling for the candidate proteins. In this regard, we examined the influence of hypoglycemic fungal polysaccharides (EPS) on the time-dependent plasma protein alterations in streptozotocin-induced diabetic rats. The 2-DE analysis of rat plasma demonstrated that about 50 proteins from about 900 visualized spots were found to be differentially regulated, of which 20 spots were identified as principal diabetes-associated proteins. The results of time profiling revealed that most of the identified proteins showed significant alterations in a time-dependent manner during 14 days, with notable trends. Nine out of the twenty proteins displayed very similar time profiles between normal healthy and EPS-treated diabetic rats. Interestingly, the altered profiles of several proteins by diabetes induction almost returned to control levels after EPS treatments. In particular, we found a clear distinction in differential expression of oxidative stress proteins (ceruloplasmin and transferrin) and lipid metabolism related proteins (Apo A-I, Apo A-IV, and Apo E) in the STZ-induced diabetic rats. The data presented here have identified and characterized the time-dependent changes in plasma proteins associated with EPS treatment in STZ-induced diabetic rats, thereby leading to the discovery of early-response and late-response biomarkers in diabetic and EPS-treated states.
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Affiliation(s)
- Sang Woo Kim
- Department of Biotechnology, and Department of Bioindustry, Daegu University, Kyungsan, Kyungbuk 712-714, Korea
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Willmore WG, Storey KB. Purification and properties of glutathione reductase from liver of the anoxia-tolerant turtle, Trachemys scripta elegans. Mol Cell Biochem 2006; 297:139-49. [PMID: 17075686 DOI: 10.1007/s11010-006-9339-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Accepted: 09/28/2006] [Indexed: 01/25/2023]
Abstract
Glutathione reductase (GR) is a homodimeric flavoprotein that catalyzes the reduction of oxidized glutathione (GSSG) using NADPH as a cofactor. The enzyme is a major component of cellular defense mechanisms against oxidative injury. In this study, GR was purified from the liver of the anoxia-tolerant turtle, Trachemys scripta elegans. The overall fold purifications were 13.3- and 12.1-fold with final specific activities of 5.5 and 1.44 U/mg of protein for control and anoxic turtle GR, respectively. SDS-PAGE of purified turtle liver GR showed a single protein band at approximately 55 kDa. Reverse phase HPLC of turtle GR revealed a single peak that had the same retention time as yeast GR. No new isoform of GR was detected in liver of T. s. elegans during anoxia. The K (m) values of turtle GR for GSSG and NADPH was 44.6 and 6.82 microM, respectively, suggesting a substantially higher affinity of turtle GR toward GSSG than most other vertebrates. Unlike other human GR, NADP(+ )did not inhibit turtle GR activity. The activation energy of turtle GR, calculated from the slope of the Arrhenius plot, was 32.2 +/- 2.64 kJ/mol. Turtle GR had high activity under a broad pH range (having activity between pHs 4 and 10; optimal activity at pH 6.5) and the enzyme maintains activity under the pH drop that occurs under anoxic conditions. The high affinity of turtle GR suggests that turtles have high redox buffering capacity of tissues to protect against oxidative stress encountered during anoxia/reoxygenation.
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Affiliation(s)
- William G Willmore
- Institute of Biochemistry, Carleton University, Ottawa, ON, Canada, K1S 5B6.
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Wang X, Xu C, Wang X, Wang D, Wang Q, Zhang B. Heat shock response and mammal adaptation to high elevation (hypoxia). ACTA ACUST UNITED AC 2006; 49:500-12. [PMID: 17172058 DOI: 10.1007/s11427-006-2027-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The mammal's high elevation (hypoxia) adaptation was studied by using the immunological and the molecular biological methods to understand the significance of Hsp (hypoxia) adaptation in the organic high elevation, through the mammal heat shock response. (1) From high elevation to low elevation (natural hypoxia): Western blot and conventional RT-PCR and real-time fluorescence quota PCR were adopted. Expression difference of heat shock protein of 70 (Hsp70) and natural expression of brain tissue of Hsp70 gene was determined in the cardiac muscle tissue among the different elevation mammals (yak). (2) From low elevation to high elevation (hypoxia induction): The mammals (domestic rabbits) from the low elevation were sent directly to the areas with different high elevations like 2300, 3300 and 5000 m above sea level to be raised for a period of 3 weeks before being slaughtered and the genetic inductive expression of the brain tissue of Hsp70 was determined with RT-PCR. The result indicated that all of the mammals at different elevations possessed their heat shock response gene. Hsp70 of the high elevation mammal rose abruptly under stress and might be induced to come into being by high elevation (hypoxia). The speedy synthesis of Hsp70 in the process of heat shock response is suitable to maintain the cells' normal physiological functions under stress. The Hsp70 has its threshold value. The altitude of 5000 m above sea level is the best condition for the heat shock response, and it starts to reduce when the altitude is over 6000 m above sea level. The Hsp70 production quantity and the cell hypoxia bearing capacity have their direct ratio.
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Affiliation(s)
- Xiaolin Wang
- Northwest Plateau Biological Research Institute, Chinese Academy of Sciences, Xining 810001, China.
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Buck LT. Adenosine as a signal for ion channel arrest in anoxia-tolerant organisms. Comp Biochem Physiol B Biochem Mol Biol 2005; 139:401-14. [PMID: 15544964 DOI: 10.1016/j.cbpc.2004.04.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 03/31/2004] [Accepted: 04/05/2004] [Indexed: 11/18/2022]
Abstract
Certain freshwater turtles and fish are extremely anoxia-tolerant, capable of surviving hours of anoxia at high temperatures and weeks to months at low temperatures. There is great interest in understanding the cellular mechanisms underlying anoxia-tolerance in these groups because they are anoxia-tolerant vertebrates and because of the far-reaching medical benefits that would be gained. It has become clear that a pre-condition of prolonged anoxic survival must involve the matching of ATP production with ATP utilization to maintain stable ATP levels during anoxia. In most vertebrates, anoxia leads to a severe decrease in ATP production without a concomitant reduction in utilization, which inevitably leads to the catastrophic events associated with cell death or necrosis. Anoxia-tolerant organisms do not increase ATP production when faced with anoxia, but rather decrease utilization to a level that can be met by anaerobic glycolysis alone. Protein synthesis and ion movement across the plasma membrane are the two main targets of regulatory processes that reduce ATP utilization and promote anoxic survival. However, the oxygen sensing and biochemical signaling mechanisms that achieve a coordinated reduction in ATP production and utilization remain unclear. One candidate-signaling compound whose extracellular concentration increases in concert with decreasing oxygen availability is adenosine. Adenosine is known to have profound effects on various aspects of tissue metabolism, including protein synthesis, ion pumping and permeability of ion channels. In this review, I will investigate the role of adenosine in the naturally anoxia-tolerant freshwater turtle and goldfish and give an overview of pathways by which adenosine concentrations are regulated.
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Affiliation(s)
- Leslie Thomas Buck
- Department of Zoology, University of Toronto, 25 Harbord St., Toronto, ON, Canada M5S 3G5.
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