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Ingelson-Filpula WA, Kadamani KL, Ojaghi M, Pamenter ME, Storey KB. Hypoxia-induced downregulation of RNA m 6A protein machinery in the naked mole-rat heart. Biochimie 2024; 225:125-132. [PMID: 38788827 DOI: 10.1016/j.biochi.2024.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 05/15/2024] [Accepted: 05/21/2024] [Indexed: 05/26/2024]
Abstract
Naked mole-rats, Heterocephalus glaber, are champion hypoxia-tolerant rodents that live under low oxygen conditions in their subterranean burrows. Detrimental effects of low oxygen can be mitigated through metabolic rate depression (MRD), metabolic reorganization, and global downregulation of nonessential cellular processes. Recent research has progressively implicated epigenetic modifications - rapid, reversible changes to gene expression that do not alter the DNA sequence itself - as major players in implementing and maintaining MRD. N6-adenosine (m6A) methylation is the most prevalent mammalian RNA modification and is responsible for pre-mRNA processing and mRNA export from the nucleus. Hence, m6A -mediated conformational changes alter the cellular fate of transcripts. The present study investigated the role of m6A RNA methylation responses to 24 h of hypoxia exposure in H. glaber cardiac tissue. Total protein levels of m6A writers/readers/erasers, m6A demethylase activity, and total m6A quantification were measured under normoxic vs. hypoxic conditions in H. glaber heart. While there was no change in either demethylase activity or total m6A content, many proteins of the m6A pathway were downregulated during hypoxia. Overall, m6A may not be a signature hypoxia-responsive characteristic in H. glaber heart, but downregulation of the protein machinery involved in m6A cycling points to an alternate biological involvement. Further research will explore other forms of RNA modifications and other epigenetic mechanisms to determine the controls on hypoxia endurance in this subterranean mammal.
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Affiliation(s)
- W Aline Ingelson-Filpula
- Affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada, K1S 5B6.
| | - Karen L Kadamani
- Biology Department, University of Ottawa, Marie-Curie Pvt, Ottawa, Ontario, K1N 9A7, Canada
| | - Mohammad Ojaghi
- Biology Department, University of Ottawa, Marie-Curie Pvt, Ottawa, Ontario, K1N 9A7, Canada
| | - Matthew E Pamenter
- Biology Department, University of Ottawa, Marie-Curie Pvt, Ottawa, Ontario, K1N 9A7, Canada; Brain and Mind Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Kenneth B Storey
- Affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada, K1S 5B6
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Naranjo M, Breedon SA, Storey KB. Cardiac microRNA expression profile in response to estivation. Biochimie 2023:S0300-9084(23)00001-9. [PMID: 36627041 DOI: 10.1016/j.biochi.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/09/2023]
Abstract
Couch's spadefoot toad (Scaphiopus couchii) spends most of the year underground in a hypometabolic state known as estivation. During this time, they overcome significant dehydration and lack of food through many mechanisms including employing metabolic rate depression (MRD), increasing urea concentration, switching to lipid oxidation as the primary energy source, and decreasing their breathing and heart rate. MicroRNA (miRNA) are known to regulate translation by targeting messenger RNA (mRNA) for degradation or temporary storage, with several studies having reported that miRNA is differentially expressed during MRD, including estivation. Thus, we hypothesized that miRNA would be involved in gene regulation during estivation in S. couchii heart. Next-generation sequencing and bioinformatic analyses were used to assess changes in miRNA expression in response to two-month estivation and to predict the downstream effects of this expression. KEGG and GO analyses indicated that ribosome and cardiac muscle contraction are among the pathways predicted to be upregulated, whereas cell signaling and fatty acid metabolism were predicted to be downregulated. Together these results suggest that miRNAs contribute to the regulation of gene expression related to cardiac muscle physiology and energy metabolism during estivation.
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Affiliation(s)
- Mairelys Naranjo
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6
| | - Sarah A Breedon
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6
| | - Kenneth B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada, K1S 5B6.
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Niles J, Singh G, Storey KB. Role of unfolded protein response and ER-associated degradation under freezing, anoxia, and dehydration stresses in the freeze-tolerant wood frogs. Cell Stress Chaperones 2023; 28:61-77. [PMID: 36346580 PMCID: PMC9877271 DOI: 10.1007/s12192-022-01307-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/25/2022] [Accepted: 10/20/2022] [Indexed: 11/09/2022] Open
Abstract
The North American amphibian, wood frogs, Rana sylvatica are the most studied anuran to comprehend vertebrate freeze tolerance. Multiple adaptations support their survival in frigid temperatures during winters, particularly their ability to produce glucose as natural cryoprotectant. Freezing and its component consequences (anoxia and dehydration) induce multiple stresses on cells. Among these is endoplasmic reticulum (ER) stress, a condition spawned by buildup of unfolded or misfolded proteins in the ER. The ER stress causes the unfolded protein response (UPR) and the ER-associated degradation (ERAD) pathway that potentially could lead to apoptosis. Immunoblotting was used to assess the responses of major proteins of the UPR and ERAD under freezing, anoxia, and dehydration stresses in the liver and skeletal muscle of the wood frogs. Targets analyzed included activating transcription factors (ATF3, ATF4, ATF6), the growth arrest and DNA damage proteins (GADD34, GADD153), and EDEM (ERAD enhancing α-mannosidase-like proteins) and XBP1 (X-box binding protein 1) proteins. UPR signaling was triggered under all three stresses (freezing, anoxia, dehydration) in liver and skeletal muscle of wood frogs with most tissue/stress responses consistent with an upregulation of the primary targets of all three UPR pathways (ATF4, ATF6, and XBP-1) to enhance the protein folding/refolding capacity under these stress conditions. Only frozen muscle showed preference for proteasomal degradation of misfolded proteins via upregulation of EDEM (ERAD). The ERAD response of liver was downregulated across three stresses suggesting preference for more refolding of misfolded/unfolded proteins. Overall, we conclude that wood frog organs activate the UPR as a means of stabilizing and repairing cellular proteins to best survive freezing exposures.
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Affiliation(s)
- Jacques Niles
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Gurjit Singh
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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Breedon SA, Gupta A, Storey KB. Regulation of Apoptosis and Autophagy During Anoxia in the Freshwater Crayfish, Faxonius virilis. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:626-639. [PMID: 35567599 DOI: 10.1007/s10126-022-10132-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
The ability of an animal to survive prolonged periods of oxygen deprivation is a critical area of study, both in terms of its importance to better understanding the physiology of these incredible animals and to its potential applicability to medical fields. The freshwater crayfish, Faxonius virilis, is one such animal capable of resisting anoxia, but it remains understudied and much of the metabolic mechanisms underlying this anoxia tolerance remain largely unprofiled. This study examines the activity and regulation of apoptosis and autophagy in F. virilis in response to 20-h anoxia. Apoptosis signaling was assessed through pro- and anti-apoptosis targets, whereas autophagy was assessed via expression response of multiple autophagy proteins. An anoxia-triggered, tissue-specific result arose, potentially based on the importance of individual organ integrity through hypometabolism. Tail muscle, which showed increased expression profiles of all three target groups, contrasted with hepatopancreas, which appeared to not be susceptible to either apoptotic or autophagic signaling during anoxia. This is likely due to the importance of the hepatopancreas, given that apoptosis or autophagy of this organ at any significant level could be fatal to the organism. The data provides a comprehensive overview of the responses and integration of multiple stress-responsive signaling pathways in F. virilis that provide a novel contribution to our understanding of pro-survival mechanisms supporting invertebrate anoxia resistance.
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Affiliation(s)
- Sarah A Breedon
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Aakriti Gupta
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, ON, Canada.
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Wu CW, Storey KB. mTOR Signaling in Metabolic Stress Adaptation. Biomolecules 2021; 11:biom11050681. [PMID: 34062764 PMCID: PMC8147357 DOI: 10.3390/biom11050681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 12/30/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is a central regulator of cellular homeostasis that integrates environmental and nutrient signals to control cell growth and survival. Over the past two decades, extensive studies of mTOR have implicated the importance of this protein complex in regulating a broad range of metabolic functions, as well as its role in the progression of various human diseases. Recently, mTOR has emerged as a key signaling molecule in regulating animal entry into a hypometabolic state as a survival strategy in response to environmental stress. Here, we review current knowledge of the role that mTOR plays in contributing to natural hypometabolic states such as hibernation, estivation, hypoxia/anoxia tolerance, and dauer diapause. Studies across a diverse range of animal species reveal that mTOR exhibits unique regulatory patterns in an environmental stressor-dependent manner. We discuss how key signaling proteins within the mTOR signaling pathways are regulated in different animal models of stress, and describe how each of these regulations uniquely contribute to promoting animal survival in a hypometabolic state.
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Affiliation(s)
- Cheng-Wei Wu
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
- Correspondence:
| | - Kenneth B. Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada;
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Protein lysine methylation in the regulation of anoxia tolerance in the red eared slider turtle, Trachemys scripta elegans. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS 2020; 34:100660. [PMID: 32066095 DOI: 10.1016/j.cbd.2020.100660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/29/2020] [Accepted: 01/30/2020] [Indexed: 11/23/2022]
Abstract
The red eared slider turtle (Trachemys scripta elegans) is a champion vertebrate facultative anaerobe, capable of surviving for several months under conditions of exceptionally low oxygen availability. The ability of the turtle to facilitate this impressive tolerance to oxygen restriction is accomplished through a dramatic reduction in non-essential cellular processes. This is done in an attempt to conserve limited ATP stores and match demand in the anoxic state, with ATP supplied primarily through anaerobic glycolysis. Determining both the non-essential and the essential cellular processes that are deemed to be anoxia-responsive in the turtle has been an intense area of study over the past few decades. As a result, recent advancements have established the influence of global metabolic controls, such as post-transcriptional and post-translational regulation of gene expression in anoxia adaptation. A remaining question is whether or not epigenetic-level regulatory mechanisms are also utilized to allow for local control over gene expression. Recently, research has begun to document lysine methylation as an anoxia-responsive post-translational histone modification, as the activities of a number of methyl-lysine regulatory enzymes are extraordinarily sensitive to oxygen availability. As a result, oxygen-dependent methyl-lysine regulatory enzymes have been of particular interest to several recent studies of animal oxygen sensitivity, including the freshwater turtle. This review will introduce the concept of lysine methylation as an oxygen-sensitive protein modification as well as a prospectus on how this modification may contribute to anoxia tolerance in the turtle.
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English SG, Hadj-Moussa H, Storey KB. MicroRNAs regulate survival in oxygen-deprived environments. J Exp Biol 2018; 221:jeb.190579. [DOI: 10.1242/jeb.190579] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/07/2018] [Indexed: 12/13/2022]
Abstract
Some animals must endure prolonged periods of oxygen deprivation to survive. One such extreme model is the Northern Crayfish (Orconectes virilis), that regularly survives year-round hypoxic and anoxic stresses in its warm stagnant summer waters and in its cold, ice-locked winter waters. To elucidate the molecular underpinnings of anoxia-resistance in this natural model, we surveyed the expression profiles of 76 highly-conserved microRNAs in crayfish hepatopancreas and tail muscle from normoxic, acute 2hr anoxia, and chronic 20hr anoxia exposures. MicroRNAs are known to regulate a diverse array of cellular functions required for environmental stress adaptations, and here we explore their role in anoxia tolerance. The tissue-specific anoxia responses observed herein, with 22 anoxia-responsive microRNAs in hepatopancreas and only 4 changing microRNAs in muscle, suggest that microRNAs facilitate a reprioritization of resources to preserve crucial organ functions. Bioinformatic microRNA target enrichment analysis predicted that the anoxia-downregulated microRNAs in hepatopancreas targeted hippo-signalling, suggesting that cell proliferation and apoptotic signalling are highly regulated in this liver-like organ during anoxia. Compellingly, miR-125-5p, miR-33-5p, and miR-190-5p, all known to target the master regulator of oxygen deprivation responses HIF1 (Hypoxia Inducible Factor-1), were anoxia-downregulated in hepatopancreas. The anoxia-increased transcript levels of the oxygen dependent subunit HIF1α, highlight a potential critical role for miRNA-HIF targeting in facilitating a successful anoxia response. Studying the cytoprotective mechanisms in place to protect against the challenges associated with surviving in oxygen-poor environments is critical to elucidating microRNAs’ vast and substantial role in the regulation of metabolism and stress in aquatic invertebrates.
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Affiliation(s)
- Simon G. English
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Hanane Hadj-Moussa
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B. Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
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