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Yang Y, Hao Z, An N, Han Y, Miao W, Storey KB, Lefai E, Liu X, Wang J, Liu S, Xie M, Chang H. Integrated transcriptomics and metabolomics reveal protective effects on heart of hibernating Daurian ground squirrels. J Cell Physiol 2023; 238:2724-2748. [PMID: 37733616 DOI: 10.1002/jcp.31123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/02/2023] [Accepted: 09/08/2023] [Indexed: 09/23/2023]
Abstract
Hibernating mammals are natural models of resistance to ischemia, hypoxia-reperfusion injury, and hypothermia. Daurian ground squirrels (spermophilus dauricus) can adapt to endure multiple torpor-arousal cycles without sustaining cardiac damage. However, the molecular regulatory mechanisms that underlie this adaptive response are not yet fully understood. This study investigates morphological, functional, genetic, and metabolic changes that occur in the heart of ground squirrels in three groups: summer active (SA), late torpor (LT), and interbout arousal (IBA). Morphological and functional changes in the heart were measured using hematoxylin-eosin (HE) staining, Masson staining, echocardiography, and enzyme-linked immunosorbent assay (ELISA). Results showed significant changes in cardiac function in the LT group as compared with SA or IBA groups, but no irreversible damage occurred. To understand the molecular mechanisms underlying these phenotypic changes, transcriptomic and metabolomic analyses were conducted to assess differential changes in gene expression and metabolite levels in the three groups of ground squirrels, with a focus on GO and KEGG pathway analysis. Transcriptomic analysis showed that differentially expressed genes were involved in the remodeling of cytoskeletal proteins, reduction in protein synthesis, and downregulation of the ubiquitin-proteasome pathway during hibernation (including LT and IBA groups), as compared with the SA group. Metabolomic analysis revealed increased free amino acids, activation of the glutathione antioxidant system, altered cardiac fatty acid metabolic preferences, and enhanced pentose phosphate pathway activity during hibernation as compared with the SA group. Combining the transcriptomic and metabolomic data, active mitochondrial oxidative phosphorylation and creatine-phosphocreatine energy shuttle systems were observed, as well as inhibition of ferroptosis signaling pathways during hibernation as compared with the SA group. In conclusion, these results provide new insights into cardio-protection in hibernators from the perspective of gene and metabolite changes and deepen our understanding of adaptive cardio-protection mechanisms in mammalian hibernators.
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Affiliation(s)
- Yingyu Yang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Ziwei Hao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Ning An
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Yuting Han
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Weilan Miao
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Kenneth B Storey
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Etienne Lefai
- INRAE, Unité de Nutrition Humaine, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Xiaoxuan Liu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Junshu Wang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Shuo Liu
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
| | - Manjiang Xie
- Department of Aerospace Physiology, Air Force Medical University, Xi'an, Shaanxi, China
| | - Hui Chang
- Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China
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2
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Heinis FI, Alvarez S, Andrews MT. Mass spectrometry of the white adipose metabolome in a hibernating mammal reveals seasonal changes in alternate fuels and carnitine derivatives. Front Physiol 2023; 14:1214087. [PMID: 37449012 PMCID: PMC10337995 DOI: 10.3389/fphys.2023.1214087] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/15/2023] [Indexed: 07/18/2023] Open
Abstract
Mammalian hibernators undergo substantial changes in metabolic function throughout the seasonal hibernation cycle. We report here the polar metabolomic profile of white adipose tissue isolated from active and hibernating thirteen-lined ground squirrels (Ictidomys tridecemlineatus). Polar compounds in white adipose tissue were extracted from five groups representing different timepoints throughout the seasonal activity-torpor cycle and analyzed using hydrophilic interaction liquid chromatography-mass spectrometry in both the positive and negative ion modes. A total of 224 compounds out of 660 features detected after curation were annotated. Unsupervised clustering using principal component analysis revealed discrete clusters representing the different seasonal timepoints throughout hibernation. One-way analysis of variance and feature intensity heatmaps revealed metabolites that varied in abundance between active and torpid timepoints. Pathway analysis compared against the KEGG database demonstrated enrichment of amino acid metabolism, purine metabolism, glycerophospholipid metabolism, and coenzyme A biosynthetic pathways among our identified compounds. Numerous carnitine derivatives and a ketone that serves as an alternate fuel source, beta-hydroxybutyrate (BHB), were among molecules found to be elevated during torpor. Elevated levels of the BHB-carnitine conjugate during torpor suggests the synthesis of beta-hydroxybutyrate in white adipose mitochondria, which may contribute directly to elevated levels of circulating BHB during hibernation.
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Affiliation(s)
- Frazer I. Heinis
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Sophie Alvarez
- Proteomics and Metabolomics Facility, Nebraska Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, United States
| | - Matthew T. Andrews
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, United States
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3
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Bernstock JD, Willis CM, Garcia-Segura ME, Gaude E, Anni D, Lee YJ, Thomas LW, Casey A, Vicario N, Leonardi T, Nicaise AM, Gessler FA, Izzy S, Buffelli MR, Seidlitz J, Srinivasan S, Murphy MP, Ashcroft M, Cambiaghi M, Hallenbeck JM, Peruzzotti-Jametti L. Integrative transcriptomic and metabolic analyses of the mammalian hibernating brain identifies a key role for succinate dehydrogenase in ischemic tolerance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.29.534718. [PMID: 37205496 PMCID: PMC10187245 DOI: 10.1101/2023.03.29.534718] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Ischemic stroke results in a loss of tissue homeostasis and integrity, the underlying pathobiology of which stems primarily from the depletion of cellular energy stores and perturbation of available metabolites 1 . Hibernation in thirteen-lined ground squirrels (TLGS), Ictidomys tridecemlineatus , provides a natural model of ischemic tolerance as these mammals undergo prolonged periods of critically low cerebral blood flow without evidence of central nervous system (CNS) damage 2 . Studying the complex interplay of genes and metabolites that unfolds during hibernation may provide novel insights into key regulators of cellular homeostasis during brain ischemia. Herein, we interrogated the molecular profiles of TLGS brains at different time points within the hibernation cycle via RNA sequencing coupled with untargeted metabolomics. We demonstrate that hibernation in TLGS leads to major changes in the expression of genes involved in oxidative phosphorylation and this is correlated with an accumulation of the tricarboxylic acid (TCA) cycle intermediates citrate, cis-aconitate, and α-ketoglutarate-αKG. Integration of the gene expression and metabolomics datasets led to the identification of succinate dehydrogenase (SDH) as the critical enzyme during hibernation, uncovering a break in the TCA cycle at that level. Accordingly, the SDH inhibitor dimethyl malonate (DMM) was able to rescue the effects of hypoxia on human neuronal cells in vitro and in mice subjected to permanent ischemic stroke in vivo . Our findings indicate that studying the regulation of the controlled metabolic depression that occurs in hibernating mammals may lead to novel therapeutic approaches capable of increasing ischemic tolerance in the CNS.
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Ball JM, Chen S, Li W. Mitochondria in cone photoreceptors act as microlenses to enhance photon delivery and confer directional sensitivity to light. SCIENCE ADVANCES 2022; 8:eabn2070. [PMID: 35235359 PMCID: PMC8890704 DOI: 10.1126/sciadv.abn2070] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/03/2022] [Indexed: 05/10/2023]
Abstract
Mammalian photoreceptors aggregate numerous mitochondria, organelles chiefly for energy production, in the ellipsoid region immediately adjacent to the light-sensitive outer segment to support the high metabolic demands of phototransduction. However, these complex, lipid-rich organelles are also poised to affect light passage into the outer segment. Here, we show, via live imaging and simulations, that despite this risk of light scattering or absorption, these tightly packed mitochondria "focus" light for entry into the outer segment and that mitochondrial remodeling affects such light concentration. This "microlens"-like feature of cone mitochondria delivers light with an angular dependence akin to the Stiles-Crawford effect (SCE), providing a simple explanation for this essential visual phenomenon that improves resolution. This new insight into the optical role of mitochondria is relevant for the interpretation of clinical ophthalmological imaging, lending support for the use of SCE as an early diagnostic tool in retinal disease.
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Affiliation(s)
- John M. Ball
- Retinal Neurophysiology Section, National Eye Institute, NIH, Bethesda, MD 20892, USA
| | - Shan Chen
- Retinal Neurophysiology Section, National Eye Institute, NIH, Bethesda, MD 20892, USA
| | - Wei Li
- Corresponding author. (J.M.B.); (W.L.)
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5
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Establishing the ground squirrel as a superb model for retinal ganglion cell disorders and optic neuropathies. J Transl Med 2021; 101:1289-1303. [PMID: 34253851 PMCID: PMC8753557 DOI: 10.1038/s41374-021-00637-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 01/08/2023] Open
Abstract
Retinal ganglion cell (RGC) death occurs after optic nerve injury due to acute trauma or chronic degenerative conditions such as optic neuropathies (e.g., glaucoma). Currently, there are no effective therapies to prevent permanent vision loss resulting from RGC death, underlining the need for research on the pathogenesis of RGC disorders. Modeling human RGC/optic nerve diseases in non-human primates is ideal because of their similarity to humans, but has practical limitations including high cost and ethical considerations. In addition, many retinal degenerative disorders are age-related making the study in primate models prohibitively slow. For these reasons, mice and rats are commonly used to model RGC injuries. However, as nocturnal mammals, these rodents have retinal structures that differ from primates - possessing less than one-tenth of the RGCs found in the primate retina. Here we report the diurnal thirteen-lined ground squirrel (TLGS) as an alternative model. Compared to other rodent models, the number and distribution of RGCs in the TLGS retina are closer to primates. The TLGS retina possesses ~600,000 RGCs with the highest density along the equatorial retina matching the location of the highest cone density (visual streak). TLGS and primate retinas also share a similar interlocking pattern between RGC axons and astrocyte processes in the retina nerve fiber layer (RNFL). In addition, using TLGS we establish a new partial optic nerve injury model that precisely controls the extent of injury while sparing a portion of the retina as an ideal internal control for investigating the pathophysiology of axon degeneration and RGC death. Moreover, in vivo optical coherence tomography (OCT) imaging and ex vivo microscopic examinations of the retina in optic nerve injured TLGS confirm RGC loss precedes proximal axon degeneration, recapitulating human pathology. Thus, the TLGS retina is an excellent model, for translational research in neurodegeneration and therapeutic neuroprotection.
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Anderson G, Maes M. Mitochondria and immunity in chronic fatigue syndrome. Prog Neuropsychopharmacol Biol Psychiatry 2020; 103:109976. [PMID: 32470498 DOI: 10.1016/j.pnpbp.2020.109976] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 05/19/2020] [Indexed: 02/07/2023]
Abstract
It is widely accepted that the pathophysiology and treatment of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) could be considerably improved. The heterogeneity of ME/CFS and the confusion over its classification have undoubtedly contributed to this, although this would seem a consequence of the complexity of the array of ME/CFS presentations and high levels of diverse comorbidities. This article reviews the biological underpinnings of ME/CFS presentations, including the interacting roles of the gut microbiome/permeability, endogenous opioidergic system, immune cell mitochondria, autonomic nervous system, microRNA-155, viral infection/re-awakening and leptin as well as melatonin and the circadian rhythm. This details not only relevant pathophysiological processes and treatment options, but also highlights future research directions. Due to the complexity of interacting systems in ME/CFS pathophysiology, clarification as to its biological underpinnings is likely to considerably contribute to the understanding and treatment of other complex and poorly managed conditions, including fibromyalgia, depression, migraine, and dementia. The gut and immune cell mitochondria are proposed to be two important hubs that interact with the circadian rhythm in driving ME/CFS pathophysiology.
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Affiliation(s)
- G Anderson
- CRC Scotland & London, Eccleston Square, London, UK.
| | - M Maes
- Dept Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Dept Psychiatry, Medical University Plovdiv, Plovdiv, Bulgaria.; IMPACT Research Center, Deakin University, Geelong, Australia
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7
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Lin JQ, Yu J, Jiang H, Zhang Y, Wan QH, Fang SG. Multi-omics analysis reveals that natural hibernation is crucial for oocyte maturation in the female Chinese alligator. BMC Genomics 2020; 21:774. [PMID: 33167853 PMCID: PMC7653761 DOI: 10.1186/s12864-020-07187-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 10/26/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Hibernation in an appropriate environment not only is important for the survival of hibernators in winter, but also is crucial for breeding in the following season for many hibernating species. However, the genetic and epigenetic mechanism underlying this process remain unclear. In the current study, we performed an integrative multi-omics analysis of gonads collected from Chinese alligators that overwintered in wild cave and artificial warmroom to explore transcriptomic and epigenomic alternations in these organs. RESULTS The data revealed that in the breeding season, female alligators were more strongly affected in terms of gene expression than males by non-hibernation because of overwintering in a warm room, especially for genes related to oocyte maturation, and this effect commenced in winter with the downregulation of STAR, which is the rate limiting factor of steroid biosynthesis. Further, miRNAs were found to play essential roles in this negative effect of overwintering in the warm room on hibernation. The upregulated miRNAs likely were responsible for the suppression of oocyte maturation in the breeding season. Finally, DNA methylome changes, especially hypomethylation, were found to play an important role in the alterations in ovarian function-related gene expression induced by non-hibernation. CONCLUSIONS Our study revealed the crucial role of hibernation quality for oocyte maturation in the Chinese alligator and the underlying genetic and epigenetic mechanisms, and highlights the importance of habitat, and especially, the overwintering site, in the conservation of not only the Chinese alligator, but also other endangered hibernators.
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Affiliation(s)
- Jian-Qing Lin
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Jun Yu
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Hua Jiang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Yi Zhang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Qiu-Hong Wan
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China
| | - Sheng-Guo Fang
- MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou, 310058, People's Republic of China.
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8
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Singhal NS, Bai M, Lee EM, Luo S, Cook KR, Ma DK. Cytoprotection by a naturally occurring variant of ATP5G1 in Arctic ground squirrel neural progenitor cells. eLife 2020; 9:55578. [PMID: 33050999 PMCID: PMC7671683 DOI: 10.7554/elife.55578] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 10/08/2020] [Indexed: 02/06/2023] Open
Abstract
Many organisms in nature have evolved mechanisms to tolerate severe hypoxia or ischemia, including the hibernation-capable Arctic ground squirrel (AGS). Although hypoxic or ischemia tolerance in AGS involves physiological adaptations, little is known about the critical cellular mechanisms underlying intrinsic AGS cell resilience to metabolic stress. Through cell survival-based cDNA expression screens in neural progenitor cells, we identify a genetic variant of AGS Atp5g1 that confers cell resilience to metabolic stress. Atp5g1 encodes a subunit of the mitochondrial ATP synthase. Ectopic expression in mouse cells and CRISPR/Cas9 base editing of endogenous AGS loci revealed causal roles of one AGS-specific amino acid substitution in mediating cytoprotection by AGS ATP5G1. AGS ATP5G1 promotes metabolic stress resilience by modulating mitochondrial morphological change and metabolic functions. Our results identify a naturally occurring variant of ATP5G1 from a mammalian hibernator that critically contributes to intrinsic cytoprotection against metabolic stress. When animals hibernate, they lower their body temperature and metabolism to conserve the energy they need to withstand cold harsh winters. One such animal is the Arctic ground squirrel, an extreme hibernator that can drop its body temperatures to below 0°C. This hibernation ability means the cells of Arctic ground squirrels can survive severe shortages of blood and oxygen. But, it is unclear how their cells are able to endure this metabolic stress. To answer this question, Singhal, Bai et al. studied the cells of Arctic ground squirrels for unique features that might make them more durable to stress. Examining the genetic code of these resilient cells revealed that Arctic ground squirrels may have a variant form of a protein called ATP5G1. This protein is found in a cellular compartment called the mitochondria, which is responsible for supplying energy to the rest of the cell and therefore plays an important role in metabolic processes. Singhal, Bai et al. found that when this variant form of ATP5G1 was introduced into the cells of mice, their mitochondria was better at coping with stress conditions, such as low oxygen, low temperature and poisoning. Using a gene editing tool to selectively substitute some of the building blocks, also known as amino acids, that make up the ATP5G1 protein revealed that improvements to the mitochondria were caused by switching specific amino acids. However, swapping these amino acids, which presumably affects the role of ATP5G1, did not completely remove the cells’ resilience to stress. This suggests that variants of other genes and proteins may also be involved in providing protection. These findings provide the first evidence of a protein variant that is responsible for protecting cells during the metabolic stress conditions caused by hibernation. The approach taken by Singhal, Bai et al. could be used to identify and study other proteins that increase resilience to metabolic stress. These findings could help develop new treatments for diseases caused by a limited blood supply to human organs, such as a stroke or heart attack.
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Affiliation(s)
- Neel S Singhal
- Department of Neurology, University of California-San Francisco, San Francisco, United States
| | - Meirong Bai
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, United States.,Department of Physiology, University of California-San Francisco, San Francisco, United States
| | - Evan M Lee
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, United States.,Department of Physiology, University of California-San Francisco, San Francisco, United States
| | - Shuo Luo
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, United States.,Department of Physiology, University of California-San Francisco, San Francisco, United States
| | - Kayleigh R Cook
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, United States.,Department of Physiology, University of California-San Francisco, San Francisco, United States
| | - Dengke K Ma
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, United States.,Department of Physiology, University of California-San Francisco, San Francisco, United States.,Innovative Genomics Institute, Berkeley, United States
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9
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Li W. Ground squirrel - A cool model for a bright vision. Semin Cell Dev Biol 2020; 106:127-134. [PMID: 32593518 DOI: 10.1016/j.semcdb.2020.06.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/10/2020] [Accepted: 06/10/2020] [Indexed: 01/04/2023]
Abstract
The great evolutionary biologist, Theodosius Dobzhansky, once said, "Nothing in biology makes sense except in the light of evolution." Vision, no doubt, is a poster child for the work of evolution. If it has not already been said, I would humbly add that "Nothing in biology makes sense except in the context of metabolism." Marrying these two thoughts together, when one chooses an animal model for vision research, the ground squirrel jumps out immediately for its unique cone dominant retina, which has evolved for its diurnal lifestyle, and for hibernation-an adaptation to unique metabolic challenges encountered during its winter sojourn.
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Affiliation(s)
- Wei Li
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, USA.
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10
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A Unique Energy-Saving Strategy during Hibernation Revealed by Multi-Omics Analysis in the Chinese Alligator. iScience 2020; 23:101202. [PMID: 32534442 PMCID: PMC7298530 DOI: 10.1016/j.isci.2020.101202] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/16/2020] [Accepted: 05/22/2020] [Indexed: 12/11/2022] Open
Abstract
Many ectotherms hibernate in face of the harsh winter conditions to improve their survival rate. However, the molecular mechanism underlying this process remains unclear. Here, we explored the hibernation mechanism of Chinese alligator using integrative multi-omics analysis. We revealed that (1) the thyroid hormone biosynthesis, nutrition absorption and metabolism, muscle contraction, urinary excretion and immunity function pathways are overall downregulated during hibernation; (2) the fat catabolism is completely suppressed, contrasting with the upregulation of hepatic fatty-acid-transporter CPT1A, suggesting a unique energy-saving strategy that differs from that in hibernating mammals; (3) the hibernation-related genes are not only directly regulated by DNA methylation but also controlled by methylation-dependent transcription networks. In addition, we identified and compared tissue-specific, species-specific, and conserved season-biased miRNAs, demonstrating complex post-transcriptional regulation during hibernation. Our study revealed the genetic and epigenetic mechanisms underlying hibernation in the Chinese alligator and provided molecular insights into the evolution of hibernation regulation.
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11
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Verra DM, Sajdak BS, Merriman DK, Hicks D. Diurnal rodents as pertinent animal models of human retinal physiology and pathology. Prog Retin Eye Res 2019; 74:100776. [PMID: 31499165 DOI: 10.1016/j.preteyeres.2019.100776] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/27/2019] [Accepted: 08/31/2019] [Indexed: 12/12/2022]
Abstract
This presentation will survey the retinal architecture, advantages, and limitations of several lesser-known rodent species that provide a useful diurnal complement to rats and mice. These diurnal rodents also possess unusually cone-rich photoreceptor mosaics that facilitate the study of cone cells and pathways. Species to be presented include principally the Sudanian Unstriped Grass Rat and Nile Rat (Arvicanthis spp.), the Fat Sand Rat (Psammomys obesus), the degu (Octodon degus) and the 13-lined ground squirrel (Ictidomys tridecemlineatus). The retina and optic nerve in several of these species demonstrate unusual resilience in the face of neuronal injury, itself an interesting phenomenon with potential translational value.
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Affiliation(s)
- Daniela M Verra
- Department of Neurobiology of Rhythms, Institut des Neurosciences Cellulaires et Intégratives (INCI), CNRS UPR 3212, Strasbourg, France
| | | | - Dana K Merriman
- Department of Biology, University of Wisconsin Oshkosh, Oshkosh, WI, USA
| | - David Hicks
- Department of Neurobiology of Rhythms, Institut des Neurosciences Cellulaires et Intégratives (INCI), CNRS UPR 3212, Strasbourg, France.
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12
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Sajdak BS, Salmon AE, Cava JA, Allen KP, Freling S, Ramamirtham R, Norton TT, Roorda A, Carroll J. Noninvasive imaging of the tree shrew eye: Wavefront analysis and retinal imaging with correlative histology. Exp Eye Res 2019; 185:107683. [PMID: 31158381 PMCID: PMC6698412 DOI: 10.1016/j.exer.2019.05.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 05/21/2019] [Accepted: 05/28/2019] [Indexed: 02/08/2023]
Abstract
Tree shrews are small mammals with excellent vision and are closely related to primates. They have been used extensively as a model for studying refractive development, myopia, and central visual processing and are becoming an important model for vision research. Their cone dominant retina (∼95% cones) provides a potential avenue to create new damage/disease models of human macular pathology and to monitor progression or treatment response. To continue the development of the tree shrew as an animal model, we provide here the first measurements of higher order aberrations along with adaptive optics scanning light ophthalmoscopy (AOSLO) images of the photoreceptor mosaic in the tree shrew retina. To compare intra-animal in vivo and ex vivo cone density measurements, the AOSLO images were matched to whole-mount immunofluorescence microscopy. Analysis of the tree shrew wavefront indicated that the optics are well-matched to the sampling of the cone mosaic and is consistent with the suggestion that juvenile tree shrews are nearly emmetropic (slightly hyperopic). Compared with in vivo measurements, consistently higher cone density was measured ex vivo, likely due to tissue shrinkage during histological processing. Tree shrews also possess massive mitochondria ("megamitochondria") in their cone inner segments, providing a natural model to assess how mitochondrial size affects in vivo retinal imagery. Intra-animal in vivo and ex vivo axial distance measurements were made in the outer retina with optical coherence tomography (OCT) and transmission electron microscopy (TEM), respectively, to determine the origin of sub-cellular cone reflectivity seen on OCT. These results demonstrate that these megamitochondria create an additional hyper-reflective outer retinal reflective band in OCT images. The ability to use noninvasive retinal imaging in tree shrews supports development of this species as a model of cone disorders.
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Affiliation(s)
- Benjamin S Sajdak
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States; Morgridge Institute for Research, Madison, WI, United States
| | - Alexander E Salmon
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Jenna A Cava
- Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Kenneth P Allen
- Biomedical Resource Center, Medical College of Wisconsin, Milwaukee, WI, United States; Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Susan Freling
- Max Planck Florida Institute for Neuroscience, Jupiter, FL, United States
| | - Ramkumar Ramamirtham
- Ophthalmology, Boston Children's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States
| | - Thomas T Norton
- Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California Berkeley, Berkeley, CA, United States
| | - Joseph Carroll
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, United States.
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13
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Nordeen CA, Martin SL. Engineering Human Stasis for Long-Duration Spaceflight. Physiology (Bethesda) 2019; 34:101-111. [PMID: 30724130 DOI: 10.1152/physiol.00046.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Suspended animation for deep-space travelers is moving out of the realm of science fiction. Two approaches are considered: the first elaborates the current medical practice of therapeutic hypothermia; the second invokes the cascade of metabolic processes naturally employed by hibernators. We explore the basis and evidence behind each approach and argue that mimicry of natural hibernation will be critical to overcome the innate limitations of human physiology for long-duration space travel.
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Affiliation(s)
- Claire A Nordeen
- Department of Emergency Medicine, Harborview Medical Center, University of Washington , Seattle, Washington
| | - Sandra L Martin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine , Aurora, Colorado
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Laíns I, Gantner M, Murinello S, Lasky-Su JA, Miller JW, Friedlander M, Husain D. Metabolomics in the study of retinal health and disease. Prog Retin Eye Res 2018; 69:57-79. [PMID: 30423446 DOI: 10.1016/j.preteyeres.2018.11.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 10/06/2018] [Accepted: 11/07/2018] [Indexed: 02/06/2023]
Abstract
Metabolomics is the qualitative and quantitative assessment of the metabolites (small molecules < 1.5 kDa) in body fluids. The metabolites are the downstream of the genetic transcription and translation processes and also downstream of the interactions with environmental exposures; thus, they are thought to closely relate to the phenotype, especially for multifactorial diseases. In the last decade, metabolomics has been increasingly used to identify biomarkers in disease, and it is currently recognized as a very powerful tool with great potential for clinical translation. The metabolome and the associated pathways also help improve our understanding of the pathophysiology and mechanisms of disease. While there has been increasing interest and research in metabolomics of the eye, the application of metabolomics to retinal diseases has been limited, even though these are leading causes of blindness. In this manuscript, we perform a comprehensive summary of the tools and knowledge required to perform a metabolomics study, and we highlight essential statistical methods for rigorous study design and data analysis. We review available protocols, summarize the best approaches, and address the current unmet need for information on collection and processing of tissues and biofluids that can be used for metabolomics of retinal diseases. Additionally, we critically analyze recent work in this field, both in animal models and in human clinical disease, including diabetic retinopathy and age-related macular degeneration. Finally, we identify opportunities for future research applying metabolomics to improve our current assessment and understanding of mechanisms of vitreoretinal diseases, and to hence improve patient assessment and care.
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Affiliation(s)
- Inês Laíns
- Retina Service, Massachusetts Eye and Ear, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, United States; Faculty of Medicine, University of Coimbra, 3000 Coimbra, Portugal.
| | - Mari Gantner
- Lowy Medical Research Institute, La Jolla, CA, 92037, United States; Scripps Research Institute, La Jolla, CA, 92037, United States.
| | - Salome Murinello
- Lowy Medical Research Institute, La Jolla, CA, 92037, United States; Scripps Research Institute, La Jolla, CA, 92037, United States.
| | - Jessica A Lasky-Su
- Systems Genetics and Genomics Unit, Channing Division of Network Medicine Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA, 02115, United States.
| | - Joan W Miller
- Retina Service, Massachusetts Eye and Ear, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, United States.
| | - Martin Friedlander
- Lowy Medical Research Institute, La Jolla, CA, 92037, United States; Scripps Research Institute, La Jolla, CA, 92037, United States.
| | - Deeba Husain
- Retina Service, Massachusetts Eye and Ear, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, United States.
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Gene expression profiling during hibernation in the European hamster. Sci Rep 2018; 8:13167. [PMID: 30177816 PMCID: PMC6120936 DOI: 10.1038/s41598-018-31506-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 08/21/2018] [Indexed: 12/14/2022] Open
Abstract
Hibernation is an exceptional physiological response to a hostile environment, characterized by a seasonal period of torpor cycles involving dramatic reductions of body temperature and metabolism, and arousal back to normothermia. As the mechanisms regulating hibernation are still poorly understood, here we analysed the expression of genes involved in energy homeostasis, torpor regulation, and daily or seasonal timing using digital droplet PCR in various central and peripheral tissues sampled at different stages of torpor/arousal cycles in the European hamster. During torpor, the hypothalamus exhibited strongly down-regulated gene expression, suggesting that hypothalamic functions were reduced during this period of low metabolic activity. During both torpor and arousal, many structures (notably the brown adipose tissue) exhibited altered expression of deiodinases, potentially leading to reduced tissular triiodothyronine availability. During the arousal phase, all analysed tissues showed increased expression of the core clock genes Per1 and Per2. Overall, our data indicated that the hypothalamus and brown adipose tissue were the tissues most affected during the torpor/arousal cycle, and that clock genes may play critical roles in resetting the body’s clocks at the beginning of the active period.
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