1
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Ojaghi M, Pamenter ME. Hypoxia impairs blood glucose homeostasis in naked mole-rat adult subordinates but not queens. J Exp Biol 2024; 227:jeb247537. [PMID: 38680085 PMCID: PMC11166464 DOI: 10.1242/jeb.247537] [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: 02/16/2024] [Accepted: 04/12/2024] [Indexed: 05/01/2024]
Abstract
Naked mole-rats (NMRs) are among the most hypoxia-tolerant mammals and metabolize only carbohydrates in hypoxia. Glucose is the primary building block of dietary carbohydrates, but how blood glucose is regulated during hypoxia has not been explored in NMRs. We hypothesized that NMRs mobilize glucose stores to support anaerobic energy metabolism in hypoxia. To test this, we treated newborn, juvenile and adult (subordinate and queen) NMRs in normoxia (21% O2) or hypoxia (7, 5 or 3% O2), while measuring metabolic rate, body temperature and blood [glucose]. We also challenged animals with glucose, insulin or insulin-like growth factor-1 (IGF-1) injections and measured the rate of glucose clearance in normoxia and hypoxia. We found that: (1) blood [glucose] increases in moderate hypoxia in queens and pups, but only in severe hypoxia in adult subordinates and juveniles; (2) glucose tolerance is similar between developmental stages in normoxia, but glucose clearance times are 2- to 3-fold longer in juveniles and subordinates than in queens or pups in hypoxia; and (3) reoxygenation accelerates glucose clearance in hypoxic subordinate adults. Mechanistically, (4) insulin and IGF-1 reduce blood [glucose] in subordinates in both normoxia but only IGF-1 impacts blood [glucose] in hypoxic queens. Our results indicate that insulin signaling is impaired by hypoxia in NMRs, but that queens utilize IGF-1 to overcome this limitation and effectively regulate blood glucose in hypoxia. This suggests that sexual maturation impacts blood glucose handling in hypoxic NMR queens, which may allow queens to spend longer periods of time in hypoxic nest chambers.
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Affiliation(s)
- Mohammad Ojaghi
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7
| | - Matthew E. Pamenter
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 9A7
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada, K1H 8M5
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2
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de Magalhães JP. The longevity bottleneck hypothesis: Could dinosaurs have shaped ageing in present-day mammals? Bioessays 2024; 46:e2300098. [PMID: 38018264 DOI: 10.1002/bies.202300098] [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: 06/06/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 11/30/2023]
Abstract
The evolution and biodiversity of ageing have long fascinated scientists and the public alike. While mammals, including long-lived species such as humans, show a marked ageing process, some species of reptiles and amphibians exhibit very slow and even the absence of ageing phenotypes. How can reptiles and other vertebrates age slower than mammals? Herein, I propose that evolving during the rule of the dinosaurs left a lasting legacy in mammals. For over 100 million years when dinosaurs were the dominant predators, mammals were generally small, nocturnal, and short-lived. My hypothesis is that such a long evolutionary pressure on early mammals for rapid reproduction led to the loss or inactivation of genes and pathways associated with long life. I call this the 'longevity bottleneck hypothesis', which is further supported by the absence in mammals of regenerative traits. Although mammals, such as humans, can evolve long lifespans, they do so under constraints dating to the dinosaur era.
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Affiliation(s)
- João Pedro de Magalhães
- Genomics of Ageing and Rejuvenation Lab, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
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3
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Hite NJ, Sudheimer KD, Anderson L, Sarko DK. Spatial Learning and Memory in the Naked Mole-Rat: Evolutionary Adaptations to a Subterranean Niche. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.879989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Evolutionary adaptation to a subterranean habitat consisting of extensive underground tunnel systems would presumably require adept spatial learning and memory, however, such capabilities have not been characterized to date in naked mole-rats (Heterocephalus glaber) which, like other members of Bathyergidae, are subterranean rodents. The goal of this study was to develop a method for effectively assessing spatial learning and memory by modifying a Hebb-Williams maze for use with these subterranean rodents. Established behavioral tests to assess spatial learning and memory have primarily focused on, and have been optimized for, more typical laboratory rodent species such as mice and rats. In the current study, we utilized species-appropriate motivators, analyzed learning curves associated with maze performance, and tested memory retention in naked mole-rats. Using a modified Hebb-Williams maze, naked mole-rats underwent 3 days of training, consisting of five trials per day wherein they could freely explore the maze in search of the reward chamber. Memory retention was then tested 1 day, 1 week, and 1 month following the last day of training. Performance was analyzed based on latency to the reward chamber, errors made, and distance traveled to reach the reward chamber. Overall, this study established a behavioral paradigm for assessing maze navigation, spatial learning, and spatial memory in subterranean rodents, including optimization of rewards and environmental motivators.
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4
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Savina A, Jaffredo T, Saldmann F, Faulkes CG, Moguelet P, Leroy C, Marmol DD, Codogno P, Foucher L, Zalc A, Viltard M, Friedlander G, Aractingi S, Fontaine RH. Single-cell transcriptomics reveals age-resistant maintenance of cell identities, stem cell compartments and differentiation trajectories in long-lived naked mole-rats skin. Aging (Albany NY) 2022; 14:3728-3756. [PMID: 35507806 PMCID: PMC9134947 DOI: 10.18632/aging.204054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/25/2022] [Indexed: 11/25/2022]
Abstract
Naked mole-rats (NMR) are subterranean rodents characterized by an unusual longevity coupled with an unexplained resistance to aging. In the present study, we performed extensive in situ analysis and single-cell RNA-sequencing comparing young and older animals. At variance with other species, NMR exhibited a striking stability of skin compartments and cell types, which remained stable over time without aging-associated changes. Remarkably, the number of stem cells was constant throughout aging. We found three classical cellular states defining a unique keratinocyte differentiation trajectory that were not altered after pseudo-temporal reconstruction. Epidermal gene expression did not change with aging either. Langerhans cell clusters were conserved, and only a higher basal stem cell expression of Igfbp3 was found in aged animals. In accordance, NMR skin healing closure was similar in young and older animals. Altogether, these results indicate that NMR skin is characterized by peculiar genetic and cellular features, different from those previously demonstrated for mice and humans. The remarkable stability of the aging NMR skin transcriptome likely reflects unaltered homeostasis and resilience.
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Affiliation(s)
| | - Thierry Jaffredo
- Institut de Biologie Paris Seine (IBPS), Laboratoire de Biologie du Développement, Sorbonne Université, CNRS, INSERM, Paris, France
| | | | - Chris G Faulkes
- Queen Mary University of London, School of Biological and Chemical Sciences, London, United Kingdom
| | - Philippe Moguelet
- Service d'Anatomie et Cytologie Pathologiques, Hôpital Tenon, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Christine Leroy
- Université Paris Cité, CNRS, INSERM, Institut Necker-Enfants Malades, Paris, France
| | | | - Patrice Codogno
- Université Paris Cité, CNRS, INSERM, Institut Necker-Enfants Malades, Paris, France
| | - Lucy Foucher
- Ecole Nationale Vétérinaire d'Alfort, Centre de Recherche Biomédicale, Maisons-Alfort, France
| | - Antoine Zalc
- Université Paris Cité, CNRS, INSERM, Institut Cochin, Paris, France
| | - Mélanie Viltard
- Fondation pour la Recherche en Physiologie, Brussels, Belgium
| | - Gérard Friedlander
- Université Paris Cité, CNRS, INSERM, Institut Necker-Enfants Malades, Paris, France
| | - Selim Aractingi
- Université Paris Cité, CNRS, INSERM, Institut Cochin, Paris, France.,Service de Dermatologie, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris, France
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5
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Developmental Plasticity in the Ossification of the Proximal Femur of Heterocephalus glaber (Bathyergidae, Rodentia). J MAMM EVOL 2022. [DOI: 10.1007/s10914-022-09602-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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6
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Cooper TK, Meyerholz DK, Beck AP, Delaney MA, Piersigilli A, Southard TL, Brayton CF. Research-Relevant Conditions and Pathology of Laboratory Mice, Rats, Gerbils, Guinea Pigs, Hamsters, Naked Mole Rats, and Rabbits. ILAR J 2022; 62:77-132. [PMID: 34979559 DOI: 10.1093/ilar/ilab022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/12/2021] [Indexed: 12/31/2022] Open
Abstract
Animals are valuable resources in biomedical research in investigations of biological processes, disease pathogenesis, therapeutic interventions, safety, toxicity, and carcinogenicity. Interpretation of data from animals requires knowledge not only of the processes or diseases (pathophysiology) under study but also recognition of spontaneous conditions and background lesions (pathology) that can influence or confound the study results. Species, strain/stock, sex, age, anatomy, physiology, spontaneous diseases (noninfectious and infectious), and neoplasia impact experimental results and interpretation as well as animal welfare. This review and the references selected aim to provide a pathology resource for researchers, pathologists, and veterinary personnel who strive to achieve research rigor and validity and must understand the spectrum of "normal" and expected conditions to accurately identify research-relevant experimental phenotypes as well as unusual illness, pathology, or other conditions that can compromise studies involving laboratory mice, rats, gerbils, guinea pigs, hamsters, naked mole rats, and rabbits.
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Affiliation(s)
- Timothy K Cooper
- Department of Comparative Medicine, Penn State Hershey Medical Center, Hershey, PA, USA
| | - David K Meyerholz
- Department of Pathology, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa, USA
| | - Amanda P Beck
- Department of Pathology, Yeshiva University Albert Einstein College of Medicine, Bronx, New York, USA
| | - Martha A Delaney
- Zoological Pathology Program, University of Illinois at Urbana-Champaign College of Veterinary Medicine, Urbana-Champaign, Illinois, USA
| | - Alessandra Piersigilli
- Laboratory of Comparative Pathology and the Genetically Modified Animal Phenotyping Service, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Teresa L Southard
- Department of Biomedical Sciences, Cornell University College of Veterinary Medicine, Ithaca, New York, USA
| | - Cory F Brayton
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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7
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The Idiosyncratic Physiological Traits of the Naked Mole-Rat; a Resilient Animal Model of Aging, Longevity, and Healthspan. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:221-254. [PMID: 34424518 DOI: 10.1007/978-3-030-65943-1_8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The subterranean-dwelling naked mole-rat (Heterocephalus glaber) is an extremophilic rodent, able to thrive in the harsh underground conditions of sub-Saharan Northeast Africa. This pelage-free mammal exhibits numerous unusual ecophysiological features including pronounced tolerance of thermolability, hypoxia, hypercapnia and noxious substances. As a mammal, the naked mole-rat provides a proof-of-concept that age-related changes in physiology are avoidable. At ages far beyond their expected lifespans given both their body size and/or the timing of early developmental milestones, naked mole-rats fail to exhibit meaningful changes in physiological health or demographic mortality. Lack of physiological deterioration with age is also evident in lean and fat mass, bone quality, and reproductive capacity. Rather, regardless of age, under basal conditions naked mole-rats appear to "idle on low" with their "shields up" as is manifested by low body temperature, metabolic rate, cardiac output and kidney concentrating ability, enabling better protection of organs and cellular function. When needed, they can nevertheless ramp up these functions, increasing cardiac output and metabolism 2-5 fold. Here we review many unusual aspects of their physiology and examine how these attributes facilitate both tolerance of the diverse suite of hostile conditions encountered in their natural milieu as well as contribute to their extraordinary longevity and resistance to common, age-related chronic diseases.
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8
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Montoya‐Sanhueza G, Bennett NC, Oosthuizen MK, Dengler‐Crish CM, Chinsamy A. Bone remodeling in the longest living rodent, the naked mole-rat: Interelement variation and the effects of reproduction. J Anat 2021; 239:81-100. [PMID: 33554344 PMCID: PMC8197955 DOI: 10.1111/joa.13404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 01/09/2021] [Accepted: 01/14/2021] [Indexed: 12/14/2022] Open
Abstract
The pattern of bone remodeling of one of the most peculiar mammals in the world, the naked mole-rat (NMR), was assessed. NMRs are known for their long lifespans among rodents and for having low metabolic rates. We assessed long-term in vivo bone labeling of subordinate individuals, as well as the patterns of bone resorption and bone remodeling in a large sample including reproductive and non-reproductive individuals (n = 70). Over 268 undecalcified thin cross-sections from the midshaft of humerus, ulna, femur and tibia were analyzed with confocal fluorescence and polarized light microscopy. Fluorochrome analysis revealed low osteogenesis, scarce bone resorption and infrequent formation of secondary osteons (Haversian systems) (i.e., slow bone turnover), thus most likely reflecting the low metabolic rates of this species. Secondary osteons occurred regardless of reproductive status. However, considerable differences in the degree of bone remodeling were found between breeders and non-breeders. Pre-reproductive stages (subordinates) exhibited quite stable skeletal homeostasis and bone structure, although the attainment of sexual maturity and beginning of reproductive cycles in female breeders triggered a series of anabolic and catabolic processes that up-regulate bone turnover, most likely associated with the increased metabolic rates of reproduction. Furthermore, bone remodeling was more frequently found in stylopodial elements compared to zeugopodial elements. Despite the limited bone remodeling observed in NMRs, the variation in the pattern of skeletal homeostasis (interelement variation) reported here represents an important aspect to understand the skeletal dynamics of a small mammal with low metabolic rates. Given the relevance of the remodeling process among mammals, this study also permitted the comparison of such process with the well-documented histomorphology of extinct therapsids (i.e., mammalian precursors), thus evidencing that bone remodeling and its endocortical compartmentalization represent ancestral features among the lineage that gave rise to mammals. It is concluded that other factors associated with development (and not uniquely related to biomechanical loading) can also have an important role in the development of bone remodeling.
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Affiliation(s)
- Germán Montoya‐Sanhueza
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
- Department of ZoologyFaculty of ScienceUniversity of South BohemiaČeské BudějoviceCzech Republic
| | - Nigel C. Bennett
- Department of Zoology and EntomologyMammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
| | - Maria K. Oosthuizen
- Department of Zoology and EntomologyMammal Research InstituteUniversity of PretoriaPretoriaSouth Africa
| | | | - Anusuya Chinsamy
- Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
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9
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Chee WY, Kurahashi Y, Kim J, Miura K, Okuzaki D, Ishitani T, Kajiwara K, Nada S, Okano H, Okada M. β-catenin-promoted cholesterol metabolism protects against cellular senescence in naked mole-rat cells. Commun Biol 2021; 4:357. [PMID: 33742113 PMCID: PMC7979689 DOI: 10.1038/s42003-021-01879-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 02/19/2021] [Indexed: 02/01/2023] Open
Abstract
The naked mole-rat (NMR; Heterocephalus glaber) exhibits cancer resistance and an exceptionally long lifespan of approximately 30 years, but the mechanism(s) underlying increased longevity in NMRs remains unclear. In the present study, we report unique mechanisms underlying cholesterol metabolism in NMR cells, which may be responsible for their anti-senescent properties. NMR fibroblasts expressed β-catenin abundantly; this high expression was linked to increased accumulation of cholesterol-enriched lipid droplets. Ablation of β-catenin or inhibition of cholesterol synthesis abolished lipid droplet formation and induced senescence-like phenotypes accompanied by increased oxidative stress. β-catenin ablation downregulated apolipoprotein F and the LXR/RXR pathway, which are involved in cholesterol transport and biogenesis. Apolipoprotein F ablation also suppressed lipid droplet accumulation and promoted cellular senescence, indicating that apolipoprotein F mediates β-catenin signaling in NMR cells. Thus, we suggest that β-catenin in NMRs functions to offset senescence by regulating cholesterol metabolism, which may contribute to increased longevity in NMRs.
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Affiliation(s)
- Woei-Yaw Chee
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Yuriko Kurahashi
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Junhyeong Kim
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Kyoko Miura
- grid.274841.c0000 0001 0660 6749Department of Aging and Longevity Research, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Daisuke Okuzaki
- grid.136593.b0000 0004 0373 3971Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan ,grid.136593.b0000 0004 0373 3971Human Immunology Lab, WPI Immunology Frontier Research Center, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Osaka, Japan
| | - Tohru Ishitani
- grid.136593.b0000 0004 0373 3971Department of Homeostatic Regulation, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Kentaro Kajiwara
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Shigeyuki Nada
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
| | - Hideyuki Okano
- grid.26091.3c0000 0004 1936 9959Department of Physiology, Keio University School of Medicine, Shinjuku-ku, Tokyo Japan
| | - Masato Okada
- grid.136593.b0000 0004 0373 3971Department of Oncogene Research, Research for Microbial Disease, Osaka University, Suita, Osaka Japan
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10
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A Sweet Story of Metabolic Innovation in the Naked Mole-Rat. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:271-286. [PMID: 34424520 DOI: 10.1007/978-3-030-65943-1_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The naked mole-rat's (Heterocephalus glaber) social and subterranean lifestyle imposes several evolutionary pressures which have shaped its physiology. One example is low oxygen availability in a crowded burrow system which the naked mole-rat has adapted to via several mechanisms. Here we describe a metabolic rewiring which enables the naked mole-rat to switch substrates in glycolysis from glucose to fructose thereby circumventing feedback inhibition at phosphofructokinase (PFK1) to allow unrestrained glycolytic flux and ATP supply under hypoxia. Preferential shift to fructose metabolism occurs in other species and biological systems as a means to provide fuel, water or like in the naked mole-rat, protection in a low oxygen environment. We review fructose metabolism through an ecological lens and suggest that the metabolic adaptation to utilize fructose in the naked mole-rat may have evolved to simultaneously combat multiple challenges posed by its hostile environment.
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11
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Smith M, Buffenstein R. Managed Care of Naked Mole-Rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1319:381-407. [PMID: 34424526 DOI: 10.1007/978-3-030-65943-1_16] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Naked mole-rats are a burgeoning model species in the field of biomedical research and are also housed at many zoos throughout the world. These mammals possess many traits that have a large impact on the way that they are kept in captivity such as their eusociality, thermolability and lack of need for drinking water. This chapter outlines the captive care and unusual housing needs of these animals. Providing information and examples from our own experiences while working with naked mole-rats for many decades. While this chapter serves as a good framework for the captive care of this mammal species, it is in no way all-encompassing but simply reflects the way in which we have managed over many years to successfully sustain our colony of thousands of animals.
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Affiliation(s)
- Megan Smith
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Rochelle Buffenstein
- Calico Life Sciences LLC, South San Francisco, CA, USA.
- Department of Pharmacology, University of Texas Health at San Antonio, San Antonio, TX, USA.
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12
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Montoya-Sanhueza G, Bennett NC, Oosthuizen MK, Dengler-Crish CM, Chinsamy A. Long bone histomorphogenesis of the naked mole-rat: Histodiversity and intraspecific variation. J Anat 2020; 238:1259-1283. [PMID: 33305850 DOI: 10.1111/joa.13381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023] Open
Abstract
Lacking fur, living in eusocial colonies and having the longest lifespan of any rodent, makes naked mole-rats (NMRs) rather peculiar mammals. Although they exhibit a high degree of polymorphism, skeletal plasticity and are considered a novel model to assess the effects of delayed puberty on the skeletal system, scarce information on their morphogenesis exists. Here, we examined a large ontogenetic sample (n = 76) of subordinate individuals to assess the pattern of bone growth and bone microstructure of fore- and hindlimb bones by using histomorphological techniques. Over 290 undecalcified thin cross-sections from the midshaft of the humerus, ulna, femur, and tibia from pups, juveniles and adults were analyzed with polarized light microscopy. Similar to other fossorial mammals, NMRs exhibited a systematic cortical thickening of their long bones, which clearly indicates a conserved functional adaptation to withstand the mechanical strains imposed during digging, regardless of their chisel-tooth predominance. We describe a high histodiversity of bone matrices and the formation of secondary osteons in NMRs. The bones of pups are extremely thin-walled and grow by periosteal bone formation coupled with considerable expansion of the medullary cavity, a process probably tightly regulated and adapted to optimize the amount of minerals destined for skeletal development, to thus allow the female breeder to produce a higher number of pups, as well as several litters. Subsequent cortical thickening in juveniles involves high amounts of endosteal bone apposition, which contrasts with the bone modeling of other mammals where a periosteal predominance exists. Adults have bone matrices predominantly consisting of parallel-fibered bone and lamellar bone, which indicate intermediate to slow rates of osteogenesis, as well as the development of poorly vascularized lamellar-zonal tissues separated by lines of arrested growth (LAGs) and annuli. These features reflect the low metabolism, low body temperature and slow growth rates reported for this species, as well as indicate a cyclical pattern of osteogenesis. The presence of LAGs in captive individuals was striking and indicates that postnatal osteogenesis and its consequent cortical stratification most likely represents a plesiomorphic thermometabolic strategy among endotherms which has been suggested to be regulated by endogenous rhythms. However, the generalized presence of LAGs in this and other subterranean taxa in the wild, as well as recent investigations on variability of environmental conditions in burrow systems, supports the hypothesis that underground environments experience seasonal fluctuations that may influence the postnatal osteogenesis of animals by limiting the extension of burrow systems during the unfavorable dry seasons and therefore the finding of food resources. Additionally, the intraspecific variation found in the formation of bone tissue matrices and vascularization suggested a high degree of developmental plasticity in NMRs, which may help explaining the polymorphism reported for this species. The results obtained here represent a valuable contribution to understanding the relationship of several aspects involved in the morphogenesis of the skeletal system of a mammal with extraordinary adaptations.
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Affiliation(s)
- Germán Montoya-Sanhueza
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa.,Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Nigel C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Maria K Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | | | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
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13
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Ward JM, Cartoceti AN, Delaney MA. Brain Lesions in Aging Zoo-Housed Naked Mole-Rats ( Heterocephalus glaber). Vet Pathol 2020; 58:142-146. [PMID: 33205701 DOI: 10.1177/0300985820969982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Naked mole-rats (NMRs) are common in the managed care of zoos and valuable models for aging research. Limited information on NMR neuropathology is available despite many studies regarding their aging physiology. Histologic sections of brain from 27 adult (5-27 years old) NMRs from 2 zoos were reviewed to determine presence or absence of lesions associated with advanced age in humans and other mammals. A majority (23/27; 85%) of NMR brains had cerebral cortical neuronal changes with rounded or angular neurons, cytoplasmic vacuoles containing pale yellow pigment, periodic acid-Schiff (PAS)-positive granules and green autofluorescence, compatible with lipofuscinosis. Less severe lesions were present in cerebellar Purkinje cells, medulla, and hippocampal neurons. The hypothalamic neuropil of all NMRs had scattered variably sized PAS-positive granules and 10 (37%) had larger round bodies consistent with corpora amylacea. The youngest NMRs, 5 to 7 years old, generally had minimal or no cerebrocortical lesions. Further studies will help understand brain aging in this long-lived species.
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Affiliation(s)
| | - Andrew N Cartoceti
- National Zoological Park, 53587Smithsonian Institution, Washington, DC, USA
| | - Martha A Delaney
- Zoological Pathology Program, College of Veterinary Medicine, 14589University of Illinois, Brookfield, IL, USA
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14
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Li W, Dong Y, Dong Q, Sun H, Zhang Y, Wang Z. The remarkable hypoxia tolerance in Brandt's voles (
Lasiopodomys brandtii
). Eur J Neurosci 2020; 53:1652-1660. [DOI: 10.1111/ejn.15012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/19/2020] [Accepted: 10/05/2020] [Indexed: 01/26/2023]
Affiliation(s)
- Wei Li
- School of Basic Medical Sciences Zhengzhou University Zhengzhou Henan Province China
| | - Yanan Dong
- School of Basic Medical Sciences Zhengzhou University Zhengzhou Henan Province China
| | - Qianqian Dong
- School of Life Sciences Zhengzhou University Zhengzhou Henan Province China
| | - Hong Sun
- School of Physical Education (Main campus) Zhengzhou University Zhengzhou Henan Province China
| | - Yifeng Zhang
- School of Life Sciences Zhengzhou University Zhengzhou Henan Province China
| | - Zhenlong Wang
- School of Life Sciences Zhengzhou University Zhengzhou Henan Province China
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15
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Translational control in the naked mole-rat as a model highly resistant to cancer. Biochim Biophys Acta Rev Cancer 2020; 1875:188455. [PMID: 33148499 DOI: 10.1016/j.bbcan.2020.188455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/23/2020] [Accepted: 10/15/2020] [Indexed: 12/24/2022]
Abstract
Dysregulation of mRNA translation is involved in the onset and progression of different types of cancer. To gain insight into novel genetic strategies to avoid this malady, we reviewed the available genomic, transcriptomic, and proteomic data about the translational machinery from the naked-mole rat (NMR) Heterocephalus glaber, a new model of study that exhibits high resistance to cancer. The principal features that might confer cancer resistance are 28S rRNA fragmentation, RPL26 and eIF4G overexpression, global downregulation of mTOR pathway, specific amino acid residues in RAPTOR (P908) and RICTOR (V1695), and the absence of 4E-BP3. These features are not only associated with cancer but also might couple longevity and adaptation to hypoxia. We propose that the regulation of translation is among the strategies endowing NMR cancer resistance.
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16
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Kim J, Chee WY, Yabuta N, Kajiwara K, Nada S, Okada M. Atg5-mediated autophagy controls apoptosis/anoikis via p53/Rb pathway in naked mole-rat fibroblasts. Biochem Biophys Res Commun 2020; 528:146-153. [PMID: 32451084 DOI: 10.1016/j.bbrc.2020.05.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 05/12/2020] [Indexed: 02/07/2023]
Abstract
The naked mole-rat (NMR, Heterocephalus glaber) is the longest-living known rodent species, with a maximum lifespan of over 30 years. NMRs exhibit negligible senescence, exceptional resistance to cancer, and high basal autophagy activity compared with mouse. The molecular mechanisms and physiological roles underlying the high basal autophagy activity in NMRs remain to be elucidated. We identified that the Atg12-Atg5 conjugate, a critical component of autophagosome formation, was highly expressed in NMR skin fibroblasts (NSFs) compared with that in mouse skin fibroblasts. Phenotypic analysis of Atg5 knockdown NSFs revealed that high basal autophagy activity in NSFs was associated with abundant expression of the Atg12-Atg5 conjugate. Atg5 knockdown in NSFs led to accumulation of dysfunctional mitochondria, and suppressed cell proliferation and cell adhesion ability, promoting apoptosis/anoikis accompanied by upregulation of the apoptosis-related genes, Bax and Noxa. Furthermore, inhibition of the p53/Rb pro-apoptotic pathway with SV40 large T antigen abolished Atg5 knockdown-induced increases in apoptosis/anoikis. Taken together, these findings suggest that high basal autophagy activity in NMR cells, mediated by Atg5, contributes to suppression of p53/Rb-induced apoptosis, which could benefit the longevity of NMR cells.
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Affiliation(s)
- Junhyeong Kim
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Woei-Yaw Chee
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Norikazu Yabuta
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kentaro Kajiwara
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Shigeyuki Nada
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Masato Okada
- Department of Oncogene Research, Research for Microbial Disease, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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17
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Mild depolarization of the inner mitochondrial membrane is a crucial component of an anti-aging program. Proc Natl Acad Sci U S A 2020; 117:6491-6501. [PMID: 32152094 PMCID: PMC7104298 DOI: 10.1073/pnas.1916414117] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The mitochondria, organelles that produce the largest amounts of ATP and reactive oxygen species (mROS) in living cells, are equipped with a universal mechanism that can completely prevent mROS production. This mechanism consists of mild depolarization of the inner mitochondrial membrane to decrease the membrane potential to a level sufficient to form ATP but insufficient to generate mROS. In short-lived mice, aging is accompanied by inactivation of the mild depolarization mechanism, resulting in chronic poisoning of the organism with mROS. However, mild depolarization still functions for many years in long-lived naked mole rats and bats. The mitochondria of various tissues from mice, naked mole rats (NMRs), and bats possess two mechanistically similar systems to prevent the generation of mitochondrial reactive oxygen species (mROS): hexokinases I and II and creatine kinase bound to mitochondrial membranes. Both systems operate in a manner such that one of the kinase substrates (mitochondrial ATP) is electrophoretically transported by the ATP/ADP antiporter to the catalytic site of bound hexokinase or bound creatine kinase without ATP dilution in the cytosol. One of the kinase reaction products, ADP, is transported back to the mitochondrial matrix via the antiporter, again through an electrophoretic process without cytosol dilution. The system in question continuously supports H+-ATP synthase with ADP until glucose or creatine is available. Under these conditions, the membrane potential, ∆ψ, is maintained at a lower than maximal level (i.e., mild depolarization of mitochondria). This ∆ψ decrease is sufficient to completely inhibit mROS generation. In 2.5-y-old mice, mild depolarization disappears in the skeletal muscles, diaphragm, heart, spleen, and brain and partially in the lung and kidney. This age-dependent decrease in the levels of bound kinases is not observed in NMRs and bats for many years. As a result, ROS-mediated protein damage, which is substantial during the aging of short-lived mice, is stabilized at low levels during the aging of long-lived NMRs and bats. It is suggested that this mitochondrial mild depolarization is a crucial component of the mitochondrial anti-aging system.
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18
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Zemlemerova ED, Kostin DS, Gromov AR, Martynov AA, Alexsandrov DY, Lavrenchenko LA. Preliminary Data on Phylogeography of the Naked Mole-Rat Heterocephalus glaber (Rodentia: Heterocephalidae). RUSS J GENET+ 2020. [DOI: 10.1134/s1022795420030175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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19
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Buffenstein R, Lewis KN, Gibney PA, Narayan V, Grimes KM, Smith M, Lin TD, Brown-Borg HM. Probing Pedomorphy and Prolonged Lifespan in Naked Mole-Rats and Dwarf Mice. Physiology (Bethesda) 2020; 35:96-111. [DOI: 10.1152/physiol.00032.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Pedomorphy, maintenance of juvenile traits throughout life, is most pronounced in extraordinarily long-lived naked mole-rats. Many of these traits (e.g., slow growth rates, low hormone levels, and delayed sexual maturity) are shared with spontaneously mutated, long-lived dwarf mice. Although some youthful traits likely evolved as adaptations to subterranean habitats (e.g., thermolability), the nature of these intrinsic pedomorphic features may also contribute to their prolonged youthfulness, longevity, and healthspan.
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Affiliation(s)
| | | | - Patrick A. Gibney
- Calico Life Sciences LLC, South San Francisco, California
- Department of Food Science, College of Agriculture and Life Sciences, Stocking Hall, Cornell University, Ithaca, New York
| | - Vikram Narayan
- Calico Life Sciences LLC, South San Francisco, California
| | - Kelly M. Grimes
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Megan Smith
- Calico Life Sciences LLC, South San Francisco, California
| | - Tzuhua D. Lin
- Calico Life Sciences LLC, South San Francisco, California
| | - Holly M. Brown-Borg
- Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota
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20
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Schulze-Makuch D. The Naked Mole-Rat: An Unusual Organism with an Unexpected Latent Potential for Increased Intelligence? Life (Basel) 2019; 9:life9030076. [PMID: 31527499 PMCID: PMC6789728 DOI: 10.3390/life9030076] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/13/2019] [Accepted: 08/28/2019] [Indexed: 11/24/2022] Open
Abstract
Naked mole-rats are eusocial, hairless mammals that are uniquely adapted to their harsh, low-oxygen subsurface habitat. Although their encephalization quotient, a controversial marker of intelligence, is low, they exhibit many features considered tell-tale signs of highly intelligent species on our planet including longevity, plasticity, social cohesion and interaction, rudimentary language, sustainable farming abilities, and maintaining sanitary conditions in their self-built complex housing structures. It is difficult to envision how naked mole-rats would reach even higher levels of intelligence in their natural sensory-challenged habitat, but such an evolutionary path cannot be excluded if they would expand their range onto the earth’s surface.
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Affiliation(s)
- Dirk Schulze-Makuch
- Astrobiology Group, Center for Astronomy and Astrophysics (ZAA), Technical University Berlin, 10623 Berlin, Germany.
- School of the Environment, Washington State University, Pullman, WA 99163, USA.
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21
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Ullrich F, Blin S, Lazarow K, Daubitz T, von Kries JP, Jentsch TJ. Identification of TMEM206 proteins as pore of PAORAC/ASOR acid-sensitive chloride channels. eLife 2019; 8:49187. [PMID: 31318332 PMCID: PMC6663466 DOI: 10.7554/elife.49187] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/17/2019] [Indexed: 01/09/2023] Open
Abstract
Acid-sensing ion channels have important functions in physiology and pathology, but the molecular composition of acid-activated chloride channels had remained unclear. We now used a genome-wide siRNA screen to molecularly identify the widely expressed acid-sensitive outwardly-rectifying anion channel PAORAC/ASOR. ASOR is formed by TMEM206 proteins which display two transmembrane domains (TMs) and are expressed at the plasma membrane. Ion permeation-changing mutations along the length of TM2 and at the end of TM1 suggest that these segments line ASOR’s pore. While not belonging to a gene family, TMEM206 has orthologs in probably all vertebrates. Currents from evolutionarily distant orthologs share activation by protons, a feature essential for ASOR’s role in acid-induced cell death. TMEM206 defines a novel class of ion channels. Its identification will help to understand its physiological roles and the diverse ways by which anion-selective pores can be formed.
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Affiliation(s)
- Florian Ullrich
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Sandy Blin
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Katina Lazarow
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Tony Daubitz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | | | - Thomas J Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany.,NeuroCure Cluster of Excellence, Charité Universitätsmedizin, Berlin, Germany
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22
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Calsolaro V, Niccolai F, Pasqualetti G, Calabrese AM, Polini A, Okoye C, Magno S, Caraccio N, Monzani F. Overt and Subclinical Hypothyroidism in the Elderly: When to Treat? Front Endocrinol (Lausanne) 2019; 10:177. [PMID: 30967841 PMCID: PMC6438852 DOI: 10.3389/fendo.2019.00177] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 03/01/2019] [Indexed: 12/13/2022] Open
Abstract
Hypothyroidism is characterized by increased thyrotropin (TSH) levels and reduced free thyroid hormone fractions while, subclinical hypothyroidism (sHT) by elevated serum TSH in the face of normal thyroid hormones. The high frequency of hypothyroidism among the general population in Western Countries made levothyroxine (LT4) one of the 10 most prescribed drugs. However, circulating TSH has been demonstrated to increase with aging, regardless the existence of an actual thyroid disease. Thus, when confronting an increase in circulating TSH levels in the elderly, especially in the oldest old, it is important to carry an appropriate diagnostic path, comprehensive of clinical picture as well as laboratory and imaging techniques. In the current review, we summarize the recommendations for a correct diagnostic workup and therapeutic approach to older people with elevated TSH value, with special attention to the presence of frailty, comorbidities, and poly-therapy. The treatment of choice for hypothyroid patients is hormone replacement with LT4 but, it is important to consider multiple factors before commencing the therapy, from the age dependent TSH increase to the presence of an actual thyroid disease and comorbidities. When treatment is necessary, a tailored therapy should be chosen, considering poly-pharmacy and frailty. A careful follow-up and treatment re-assessment should be always considered to avoid the risk of over-treatment. It is important to stress the need of educating the patient for a correct administration of LT4, particularly when poly-therapy is in place, and the importance of a tailored therapeutic approach and follow-up, to avoid overtreatment.
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Affiliation(s)
- Valeria Calsolaro
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
- Neurology Imaging Unit, Imperial College, London, United Kingdom
- *Correspondence: Valeria Calsolaro
| | - Filippo Niccolai
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Giuseppe Pasqualetti
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Alessia Maria Calabrese
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Antonio Polini
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Chukwuma Okoye
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Silvia Magno
- Obesity Center at the Endocrinology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Nadia Caraccio
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Fabio Monzani
- Geriatrics Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
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23
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Responses to pup vocalizations in subordinate naked mole-rats are induced by estradiol ingested through coprophagy of queen's feces. Proc Natl Acad Sci U S A 2018; 115:9264-9269. [PMID: 30150390 DOI: 10.1073/pnas.1720530115] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Naked mole-rats form eusocial colonies consisting of a single breeding female (the queen), several breeding males, and sexually immature adults (subordinates). Subordinates are cooperative and provide alloparental care by huddling and retrieving pups to the nest. However, the physiological mechanism(s) underlying alloparental behavior of nonbreeders remains undetermined. Here, we examined the response of subordinates to pup voice and the fecal estradiol concentrations of subordinates during the three reproductive periods of the queen, including gestation, postpartum, and nonlactating. Subordinate response to pup voice was observed only during the queen's postpartum and was preceded by an incremental rise in subordinates' fecal estradiol concentrations during the queen's gestation period, which coincided with physiological changes in the queen. We hypothesized that the increased estradiol in the queen's feces was disseminated to subordinates through coprophagy, which stimulated subordinates' responses to pup vocalizations. To test this hypothesis, we fed subordinates either fecal pellets from pregnant queens or pellets from nonpregnant queens amended with estradiol for 9 days and examined their response to recorded pup voice. In both treatments, the subordinates exhibited a constant level of response to pup voice during the feeding period but became more responsive 4 days after the feeding period. Thus, we believe that we have identified a previously unknown system of communication in naked mole-rats, in which a hormone released by one individual controls the behavior of another individual and influences the level of responsiveness among subordinate adults to pup vocal signals, thereby contributing to the alloparental pup care by subordinates.
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24
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Montoya-Sanhueza G, Chinsamy A. Cortical bone adaptation and mineral mobilization in the subterranean mammal Bathyergus suillus (Rodentia: Bathyergidae): effects of age and sex. PeerJ 2018; 6:e4944. [PMID: 29910978 PMCID: PMC6001714 DOI: 10.7717/peerj.4944] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/21/2018] [Indexed: 01/08/2023] Open
Abstract
The patterns of bone modeling and mineral mobilization (skeletal homeostasis) among mammals other than humans and laboratory rodents are still poorly known. In this study we assessed the pattern of bone formation and bone resorption in the femur of a wild population of Cape dune molerats, Bathyergus suillus (n = 41) (Bathyergidae), a solitary subterranean mammal with a marked extended longevity among rodents, and which also lives in a naturally deficient state of vitamin D. In order to determine ontogenetic and sex effects on histomorphometric parameters of transversal undecalcified bone sections, two-way ANOVA, linear mixed-effects model and regression statistical analyses were performed. During ontogeny, B. suillus increased their cross sectional area, cortical area and cortical thickness, and most importantly, they showed scarce endosteal bone resorption which resulted in a retained medullary cavity size during ontogeny. This resulted in a positively imbalanced bone modeling, where bone formation considerably surpasses bone loss by almost 100-fold in adulthood. This differs markedly from other terrestrial mammals with relatively thin cortical walls. Regarding bone loss and remodeling, three main processes involving intracortical resorption were observed: modeling-related bone loss in early postnatal growth; secondary osteon formation occurring in both sexes; and subendosteal secondary reconstruction observed only in females. The latter is accompanied by females having six-fold more relative bone loss than males, which is evidenced by the development of enlarged resorption cavities (RCs) distributed circumferentially around the medullary cavity. Males have smaller, more circular and randomly distributed RCs. In general, our data indicate no age-related decline in mineral content in B. suillus, and provides strong support for a pattern of sexual dimorphism in skeletal homeostasis, similar to that occurring in humans and other mammals, with females losing more bone throughout aging as compared to males due to reproductive factors. Interestingly as well, despite the high mechanical loads experienced during burrow construction, bone remodeling in B. suillus is kept at very low levels throughout their lifespan, and dense Haversian tissue never forms. This study represents the first comprehensive assessment of skeletal homeostasis in a subterranean mammal, and it enables a better understanding of the complex processes governing the acquisition and maintenance of bone properties in this species with extraordinary fossorial adaptations.
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Affiliation(s)
- Germán Montoya-Sanhueza
- Department of Biological Sciences, University of Cape Town, Cape Town, Western Cape, South Africa
| | - Anusuya Chinsamy
- Department of Biological Sciences, University of Cape Town, Cape Town, Western Cape, South Africa
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25
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Beebe NL, Schofield BR. Perineuronal nets in subcortical auditory nuclei of four rodent species with differing hearing ranges. J Comp Neurol 2018; 526:972-989. [PMID: 29277975 DOI: 10.1002/cne.24383] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/20/2017] [Accepted: 12/09/2017] [Indexed: 12/19/2022]
Abstract
Perineuronal nets (PNs) are aggregates of extracellular matrix molecules that surround some neurons in the brain. While PNs occur widely across many cortical areas, subcortical PNs are especially associated with motor and auditory systems. The auditory system has recently been suggested as an ideal model system for studying PNs and their functions. However, descriptions of PNs in subcortical auditory areas vary, and it is unclear whether the variation reflects species differences or differences in staining techniques. Here, we used two staining techniques (one lectin stain and one antibody stain) to examine PN distribution in the subcortical auditory system of four different species: guinea pigs (Cavia porcellus), mice (Mus musculus, CBA/CaJ strain), Long-Evans rats (Rattus norvegicus), and naked mole-rats (Heterocephalus glaber). We found that some auditory nuclei exhibit dramatic differences in PN distribution among species while other nuclei have consistent PN distributions. We also found that PNs exhibit molecular heterogeneity, and can stain with either marker individually or with both. PNs within a given nucleus can be heterogeneous or homogenous in their staining patterns. We compared PN staining across the frequency axes of tonotopically organized nuclei and among species with different hearing ranges. PNs were distributed non-uniformly across some nuclei, but only rarely did this appear related to the tonotopic axis. PNs were prominent in all four species; we found no systematic relationship between the hearing range and the number, staining patterns or distribution of PNs in the auditory nuclei.
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Affiliation(s)
- Nichole L Beebe
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, 44272
| | - Brett R Schofield
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, 44272
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26
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Lee SG, Mikhalchenko AE, Yim SH, Lobanov AV, Park JK, Choi KH, Bronson RT, Lee CK, Park TJ, Gladyshev VN. Naked Mole Rat Induced Pluripotent Stem Cells and Their Contribution to Interspecific Chimera. Stem Cell Reports 2017; 9:1706-1720. [PMID: 29107591 PMCID: PMC5829328 DOI: 10.1016/j.stemcr.2017.09.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 12/16/2022] Open
Abstract
Naked mole rats (NMRs) are exceptionally long-lived, cancer-resistant rodents. Identifying the defining characteristics of these traits may shed light on aging and cancer mechanisms. Here, we report the generation of induced pluripotent stem cells (iPSCs) from NMR fibroblasts and their contribution to mouse-NMR chimeric embryos. Efficient reprogramming could be observed under N2B27+2i conditions. The iPSCs displayed a characteristic morphology, expressed pluripotent markers, formed embryoid bodies, and showed typical differentiation patterns. Interestingly, NMR embryonic fibroblasts and the derived iPSCs had propensity for a tetraploid karyotype and were resistant to forming teratomas, but within mouse blastocysts they contributed to both interspecific placenta and fetus. Gene expression patterns of NMR iPSCs were more similar to those of human than mouse iPSCs. Overall, we uncovered unique features of NMR iPSCs and report a mouse-NMR chimeric model. The iPSCs and associated cell culture systems can be used for a variety of biological and biomedical applications.
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Affiliation(s)
- Sang-Goo Lee
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Aleksei E Mikhalchenko
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Center for Data-Intensive Biomedicine and Biotechnology, Skolkovo Institute of Science and Technology, Moscow 143028, Russia
| | - Sun Hee Yim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Alexei V Lobanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jin-Kyu Park
- Department of Agricultural Biotechnology, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 151-921, Korea
| | - Kwang-Hwan Choi
- Department of Agricultural Biotechnology, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 151-921, Korea
| | - Roderick T Bronson
- Rodent Histopathology Laboratory, Harvard Medical School, Boston MA 02115, USA
| | - Chang-Kyu Lee
- Department of Agricultural Biotechnology, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 151-921, Korea; Institute of Green Bio Science and Technology, Seoul National University, Pyeongchang, Gangwon-do 232-916, Korea
| | - Thomas J Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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27
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Schuhmacher LN, Smith ESJ. Expression of acid-sensing ion channels and selection of reference genes in mouse and naked mole rat. Mol Brain 2016; 9:97. [PMID: 27964758 PMCID: PMC5154015 DOI: 10.1186/s13041-016-0279-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/02/2016] [Indexed: 12/19/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are a family of ion channels comprised of six subunits encoded by four genes and they are expressed throughout the peripheral and central nervous systems. ASICs have been implicated in a wide range of physiological and pathophysiological processes: pain, breathing, synaptic plasticity and excitotoxicity. Unlike mice and humans, naked mole-rats do not perceive acid as a noxious stimulus, even though their sensory neurons express functional ASICs, likely an adaptation to living in a hypercapnic subterranean environment. Previous studies of ASIC expression in the mammalian nervous system have often not examined all subunits, or have failed to adequately quantify expression between tissues; to date there has been no attempt to determine ASIC expression in the central nervous system of the naked mole-rat. Here we perform a geNorm study to identify reliable housekeeping genes in both mouse and naked mole-rat and then use quantitative real-time PCR to estimate the relative amounts of ASIC transcripts in different tissues of both species. We identify RPL13A (ribosomal protein L13A) and CANX (calnexin), and β-ACTIN and EIF4A (eukaryotic initiation factor 4a) as being the most stably expressed housekeeping genes in mouse and naked mole-rat, respectively. In both species, ASIC3 was most highly expressed in dorsal root ganglia (DRG), and ASIC1a, ASIC2b and ASIC3 were more highly expressed across all brain regions compared to the other subunits. We also show that ASIC4, a proton-insensitive subunit of relatively unknown function, was highly expressed in all mouse tissues apart from DRG and hippocampus, but was by contrast the lowliest expressed ASIC in all naked mole-rat tissues.
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Affiliation(s)
- Laura-Nadine Schuhmacher
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.,Department of Cell & Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Ewan St John Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
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28
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Jiang JJ, Cheng LH, Wu H, He YH, Kong QP. Insights into long noncoding RNAs of naked mole rat ( Heterocephalus glaber) and their potential association with cancer resistance. Epigenetics Chromatin 2016; 9:51. [PMID: 27833660 PMCID: PMC5103457 DOI: 10.1186/s13072-016-0101-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/25/2016] [Indexed: 02/01/2023] Open
Abstract
Background Long noncoding RNAs (lncRNAs) are a class of ubiquitous noncoding RNAs and have been found to act as tumor suppressors or oncogenes, which dramatically altered our understanding of cancer. Naked mole rat (NMR, Heterocephalus glaber) is an exceptionally long-lived and cancer-resistant rodent; however, whether lncRNAs play roles in cancer resistance in this seductive species remains unknown. Results In this study, we developed a pipeline and identified a total of 4422 lncRNAs across the NMR genome based on 12 published transcriptomes. Systematic analysis revealed that NMR lncRNAs share many common characteristics with other vertebrate species, such as tissue specificity and low expression. BLASTN against with 1057 human cancer-related lncRNAs showed that only 5 NMR lncRNAs displayed homology, demonstrating the low sequence conservation between NMR lncRNAs and human cancer-related lncRNAs. Further correlation analysis of lncRNAs and protein-coding genes indicated that a total of 1295 lncRNAs were intensively coexpressed (r ≥ 0.9 or r ≤ −0.9, cP value ≤ 0.01) with potential tumor-suppressor genes in NMR, and 194 lncRNAs exhibited strong correlation (r ≥ 0.8 or r ≤ −0.8, cP value ≤ 0.01) with four high-molecular-mass hyaluronan related genes that were previously identified to play key roles in cancer resistance of NMR. Conclusion In this study, we provide the first comprehensive genome-wide analysis of NMR lncRNAs and their possible associations with cancer resistance. Our results suggest that lncRNAs may have important effects on anticancer mechanism in NMR. Electronic supplementary material The online version of this article (doi:10.1186/s13072-016-0101-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jian-Jun Jiang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming, 650223 China ; Kunming College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Le-Hua Cheng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming, 650223 China ; The School of Life Science, University of Science and Technology of China, Hefei, 230027 China
| | - Huan Wu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming, 650223 China ; Kunming College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yong-Han He
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming, 650223 China
| | - Qing-Peng Kong
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming, 650223 China
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Lewis KN, Soifer I, Melamud E, Roy M, McIsaac RS, Hibbs M, Buffenstein R. Unraveling the message: insights into comparative genomics of the naked mole-rat. Mamm Genome 2016; 27:259-78. [PMID: 27364349 PMCID: PMC4935753 DOI: 10.1007/s00335-016-9648-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/09/2016] [Indexed: 12/21/2022]
Abstract
Animals have evolved to survive, and even thrive, in different environments. Genetic adaptations may have indirectly created phenotypes that also resulted in a longer lifespan. One example of this phenomenon is the preternaturally long-lived naked mole-rat. This strictly subterranean rodent tolerates hypoxia, hypercapnia, and soil-based toxins. Naked mole-rats also exhibit pronounced resistance to cancer and an attenuated decline of many physiological characteristics that often decline as mammals age. Elucidating mechanisms that give rise to their unique phenotypes will lead to better understanding of subterranean ecophysiology and biology of aging. Comparative genomics could be a useful tool in this regard. Since the publication of a naked mole-rat genome assembly in 2011, analyses of genomic and transcriptomic data have enabled a clearer understanding of mole-rat evolutionary history and suggested molecular pathways (e.g., NRF2-signaling activation and DNA damage repair mechanisms) that may explain the extraordinarily longevity and unique health traits of this species. However, careful scrutiny and re-analysis suggest that some identified features result from incorrect or imprecise annotation and assembly of the naked mole-rat genome: in addition, some of these conclusions (e.g., genes involved in cancer resistance and hairlessness) are rejected when the analysis includes additional, more closely related species. We describe how the combination of better study design, improved genomic sequencing techniques, and new bioinformatic and data analytical tools will improve comparative genomics and ultimately bridge the gap between traditional model and nonmodel organisms.
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Affiliation(s)
- Kaitlyn N Lewis
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Ilya Soifer
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Eugene Melamud
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Margaret Roy
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - R Scott McIsaac
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA
| | - Matthew Hibbs
- Computer Science Department, Trinity University, San Antonio, TX, 78212, USA
| | - Rochelle Buffenstein
- Calico Life Sciences LLC, 1170 Veterans Blvd, South San Francisco, CA, 94080, USA.
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30
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Triplett JC, Swomley AM, Kirk J, Grimes KM, Lewis KN, Orr ME, Rodriguez KA, Cai J, Klein JB, Buffenstein R, Butterfield DA. Reaching Out to Send a Message: Proteins Associated with Neurite Outgrowth and Neurotransmission are Altered with Age in the Long-Lived Naked Mole-Rat. Neurochem Res 2016; 41:1625-34. [DOI: 10.1007/s11064-016-1877-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 02/06/2016] [Accepted: 02/18/2016] [Indexed: 10/22/2022]
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Shao Y, Li JX, Ge RL, Zhong L, Irwin DM, Murphy RW, Zhang YP. Genetic adaptations of the plateau zokor in high-elevation burrows. Sci Rep 2015; 5:17262. [PMID: 26602147 PMCID: PMC4658562 DOI: 10.1038/srep17262] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/27/2015] [Indexed: 12/21/2022] Open
Abstract
The plateau zokor (Myospalax baileyi) spends its entire life underground in sealed burrows. Confronting limited oxygen and high carbon dioxide concentrations, and complete darkness, they epitomize a successful physiological adaptation. Here, we employ transcriptome sequencing to explore the genetic underpinnings of their adaptations to this unique habitat. Compared to Rattus norvegicus, genes belonging to GO categories related to energy metabolism (e.g. mitochondrion and fatty acid beta-oxidation) underwent accelerated evolution in the plateau zokor. Furthermore, the numbers of positively selected genes were significantly enriched in the gene categories involved in ATPase activity, blood vessel development and respiratory gaseous exchange, functional categories that are relevant to adaptation to high altitudes. Among the 787 genes with evidence of parallel evolution, and thus identified as candidate genes, several GO categories (e.g. response to hypoxia, oxygen homeostasis and erythrocyte homeostasis) are significantly enriched, are two genes, EPAS1 and AJUBA, involved in the response to hypoxia, where the parallel evolved sites are at positions that are highly conserved in sequence alignments from multiple species. Thus, accelerated evolution of GO categories, positive selection and parallel evolution at the molecular level provide evidences to parse the genetic adaptations of the plateau zokor for living in high-elevation burrows.
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Affiliation(s)
- Yong Shao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Kunming College of Life Science, University of the Chinese Academy of Sciences, Kunming 650204, China
| | - Jin-Xiu Li
- Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
| | - Ri-Li Ge
- Key Laboratory for High Altitude Medicine of Ministry of Chinese Education and Research Center for High Altitude Medicine, Qinghai University, Xining 810001, China
| | - Li Zhong
- Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
| | - David M Irwin
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, M5S 1A8, Canada.,Banting and Best Diabetes Centre, University of Toronto, Ontario, M5S 1A8, Canada
| | - Robert W Murphy
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Centre for Biodiversity and Conservation Biology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ont., M5S 2C6, Canada
| | - Ya-Ping Zhang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China.,Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming 650091, China
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32
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Kogan V, Molodtsov I, Menshikov LI, Reis RJS, Fedichev P. Stability analysis of a model gene network links aging, stress resistance, and negligible senescence. Sci Rep 2015; 5:13589. [PMID: 26316217 PMCID: PMC4551969 DOI: 10.1038/srep13589] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 07/31/2015] [Indexed: 12/20/2022] Open
Abstract
Several animal species are considered to exhibit what is called negligible senescence, i.e. they do not show signs of functional decline or any increase of mortality with age. Recent studies in naked mole rat and long-lived sea urchins showed that these species do not alter their gene-expression profiles with age as much as other organisms do. This is consistent with exceptional endurance of naked mole rat tissues to various genotoxic stresses. We conjectured, therefore, that the lifelong transcriptional stability of an organism may be a key determinant of longevity. We analyzed the stability of a simple genetic-network model and found that under most common circumstances, such a gene network is inherently unstable. Over a time it undergoes an exponential accumulation of gene-regulation deviations leading to death. However, should the repair systems be sufficiently effective, the gene network can stabilize so that gene damage remains constrained along with mortality of the organism. We investigate the relationship between stress-resistance and aging and suggest that the unstable regime may provide a mathematical basis for the Gompertz "law" of aging in many species. At the same time, this model accounts for the apparently age-independent mortality observed in some exceptionally long-lived animals.
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Affiliation(s)
- Valeria Kogan
- Moscow Institute of Physics and Technology, 141700, Institutskii per. 9, Dolgoprudny, Moscow Region, Russian Federation
- Gero Limited, Unit 1, 12/F, International Commerce Center, 1 Austin Road West, Kowloon, Hong Kong
| | - Ivan Molodtsov
- Moscow Institute of Physics and Technology, 141700, Institutskii per. 9, Dolgoprudny, Moscow Region, Russian Federation
- Gero Limited, Unit 1, 12/F, International Commerce Center, 1 Austin Road West, Kowloon, Hong Kong
| | - Leonid I. Menshikov
- Gero Limited, Unit 1, 12/F, International Commerce Center, 1 Austin Road West, Kowloon, Hong Kong
- Northern (Arctic) Federal University, 163002, Severnaya Dvina Emb. 17, Arkhangelsk, Russian Federation
| | - Robert J. Shmookler Reis
- Central Arkansas Veterans Healthcare System, Little Rock, AR, USA
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Peter Fedichev
- Moscow Institute of Physics and Technology, 141700, Institutskii per. 9, Dolgoprudny, Moscow Region, Russian Federation
- Gero Limited, Unit 1, 12/F, International Commerce Center, 1 Austin Road West, Kowloon, Hong Kong
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Buffenstein R, Nelson OL, Corbit KC. Questioning the preclinical paradigm: natural, extreme biology as an alternative discovery platform. Aging (Albany NY) 2015; 6:913-20. [PMID: 25553771 PMCID: PMC4276785 DOI: 10.18632/aging.100704] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The pace at which science continues to advance is astonishing. From cosmology, microprocessors, structural engineering, and DNA sequencing our lives are continually affected by science-based technology. However, progress in treating human ailments, especially age-related conditions such as cancer and Alzheimer's disease, moves at a relative snail's pace. Given that the amount of investment is not disproportionately low, one has to question why our hopes for the development of efficacious drugs for such grievous illnesses have been frustratingly unrealized. Here we discuss one aspect of drug development –rodent models – and propose an alternative approach to discovery research rooted in evolutionary experimentation. Our goal is to accelerate the conversation around how we can move towards more translative preclinical work.
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Affiliation(s)
- Rochelle Buffenstein
- Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, TX University of Texas Health Science Center at San Antonio, TX USA
| | - O Lynne Nelson
- Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 9916, USA
| | - Kevin C Corbit
- Department of Metabolic Disorders, Amgen, Inc., Thousand Oaks, CA 91360, USA
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Abstract
PIWI-interacting RNAs (piRNAs) are a class of small RNAs that are 24-31 nucleotides in length. They associate with PIWI proteins, which constitute a germline-specific subclade of the Argonaute family, to form effector complexes known as piRNA-induced silencing complexes, which repress transposons via transcriptional or posttranscriptional mechanisms and maintain germline genome integrity. In addition to having a role in transposon silencing, piRNAs in diverse organisms function in the regulation of cellular genes. In some cases, piRNAs have shown transgenerational inheritance to pass on the memory of "self" and "nonself," suggesting a contribution to various cellular processes over generations. Many piRNA factors have been identified; however, both the molecular mechanisms leading to the production of mature piRNAs and the effector phases of gene silencing are still enigmatic. Here, we summarize the current state of our knowledge on the biogenesis of piRNA, its biological functions, and the underlying mechanisms.
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Affiliation(s)
- Yuka W Iwasaki
- Department of Molecular Biology, Keio University School of Medicine, Tokyo 160-8582, Japan;
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35
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36
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Puissant MM, Echert AE, Yang C, Mouradian GC, Novotny T, Liu P, Liang M, Hodges MR. RNASeq-derived transcriptome comparisons reveal neuromodulatory deficiency in the CO₂ insensitive brown Norway rat. J Physiol 2014; 593:415-30. [PMID: 25630262 DOI: 10.1113/jphysiol.2014.285171] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 10/22/2014] [Indexed: 11/08/2022] Open
Abstract
Raphé-derived serotonin (5-HT) and thyrotropin-releasing hormone (TRH) play important roles in fundamental, homeostatic control systems such as breathing and specifically the ventilatory CO2 chemoreflex. Brown Norway (BN) rats exhibit an inherent and severe ventilatory insensitivity to hypercapnia but also exhibit relatively normal ventilation at rest and during other conditions, similar to multiple genetic models of 5-HT system dysfunction in mice. Herein, we tested the hypothesis that the ventilatory insensitivity to hypercapnia in BN rats is due to altered raphé gene expression and the consequent deficiencies in raphé-derived neuromodulators such as TRH. Medullary raphé transcriptome comparisons revealed lower expression of multiple 5-HT neuron-specific genes in BN compared to control Dahl salt-sensitive rats, predictive of reduced central nervous system monoamines by bioinformatics analyses and confirmed by high-performance liquid chromatography measurements. In particular, raphé Trh mRNA and peptide levels were significantly reduced in BN rats, and injections of the stable TRH analogue Taltirelin (TAL) stimulated breathing dose-dependently, with greater effects in BN versus control Sprague-Dawley rats. Importantly, TAL also effectively normalized the ventilatory CO2 chemoreflex in BN rats, but TAL did not affect CO2 sensitivity in control Sprague-Dawley rats. These data establish a molecular basis of the neuromodulatory deficiency in BN rats, and further suggest an important functional role for TRH signalling in the mammalian CO2 chemoreflex.
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Affiliation(s)
- Madeleine M Puissant
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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37
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Henning Y, Vole C, Begall S, Bens M, Broecker-Preuss M, Sahm A, Szafranski K, Burda H, Dammann P. Unusual ratio between free thyroxine and free triiodothyronine in a long-lived mole-rat species with bimodal ageing. PLoS One 2014; 9:e113698. [PMID: 25409169 PMCID: PMC4237498 DOI: 10.1371/journal.pone.0113698] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/27/2014] [Indexed: 12/03/2022] Open
Abstract
Ansell's mole-rats (Fukomys anselli) are subterranean, long-lived rodents, which live in eusocial families, where the maximum lifespan of breeders is twice as long as that of non-breeders. Their metabolic rate is significantly lower than expected based on allometry, and their retinae show a high density of S-cone opsins. Both features may indicate naturally low thyroid hormone levels. In the present study, we sequenced several major components of the thyroid hormone pathways and analyzed free and total thyroxine and triiodothyronine in serum samples of breeding and non-breeding F. anselli to examine whether a) their thyroid hormone system shows any peculiarities on the genetic level, b) these animals have lower hormone levels compared to euthyroid rodents (rats and guinea pigs), and c) reproductive status, lifespan and free hormone levels are correlated. Genetic analyses confirmed that Ansell's mole-rats have a conserved thyroid hormone system as known from other mammalian species. Interspecific comparisons revealed that free thyroxine levels of F. anselli were about ten times lower than of guinea pigs and rats, whereas the free triiodothyronine levels, the main biologically active form, did not differ significantly amongst species. The resulting fT4:fT3 ratio is unusual for a mammal and potentially represents a case of natural hypothyroxinemia. Comparisons with total thyroxine levels suggest that mole-rats seem to possess two distinct mechanisms that work hand in hand to downregulate fT4 levels reliably. We could not find any correlation between free hormone levels and reproductive status, gender or weight. Free thyroxine may slightly increase with age, based on sub-significant evidence. Hence, thyroid hormones do not seem to explain the different ageing rates of breeders and non-breeders. Further research is required to investigate the regulatory mechanisms responsible for the unusual proportion of free thyroxine and free triiodothyronine.
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Affiliation(s)
- Yoshiyuki Henning
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
- * E-mail:
| | - Christiane Vole
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Sabine Begall
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Martin Bens
- Genome Analysis, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Martina Broecker-Preuss
- Department of Endocrinology and Metabolism and Division of Laboratory Research, University Hospital, University of Duisburg-Essen, Essen, Germany
| | - Arne Sahm
- Genome Analysis, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Karol Szafranski
- Genome Analysis, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Hynek Burda
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Philip Dammann
- Department of General Zoology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
- Central Animal Laboratory, University Hospital, University of Duisburg-Essen, Essen, Germany
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Fang X, Seim I, Huang Z, Gerashchenko MV, Xiong Z, Turanov AA, Zhu Y, Lobanov AV, Fan D, Yim SH, Yao X, Ma S, Yang L, Lee SG, Kim EB, Bronson RT, Šumbera R, Buffenstein R, Zhou X, Krogh A, Park TJ, Zhang G, Wang J, Gladyshev VN. Adaptations to a subterranean environment and longevity revealed by the analysis of mole rat genomes. Cell Rep 2014; 8:1354-64. [PMID: 25176646 PMCID: PMC4350764 DOI: 10.1016/j.celrep.2014.07.030] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 05/11/2014] [Accepted: 07/17/2014] [Indexed: 02/06/2023] Open
Abstract
Subterranean mammals spend their lives in dark, unventilated environments that are rich in carbon dioxide and ammonia and low in oxygen. Many of these animals are also long-lived and exhibit reduced aging-associated diseases, such as neurodegenerative disorders and cancer. We sequenced the genome of the Damaraland mole rat (DMR, Fukomys damarensis) and improved the genome assembly of the naked mole rat (NMR, Heterocephalus glaber). Comparative genome analyses, along with the transcriptomes of related subterranean rodents, revealed candidate molecular adaptations for subterranean life and longevity, including a divergent insulin peptide, expression of oxygen-carrying globins in the brain, prevention of high CO2-induced pain perception, and enhanced ammonia detoxification. Juxtaposition of the genomes of DMR and other more conventional animals with the genome of NMR revealed several truly exceptional NMR features: unusual thermogenesis, an aberrant melatonin system, pain insensitivity, and unique processing of 28S rRNA. Together, these genomes and transcriptomes extend our understanding of subterranean adaptations, stress resistance, and longevity.
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Affiliation(s)
- Xiaodong Fang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Inge Seim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | | | - Maxim V Gerashchenko
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Anton A Turanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Alexei V Lobanov
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Sun Hee Yim
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Siming Ma
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Lan Yang
- BGI-Shenzhen, Shenzhen 518083, China
| | - Sang-Goo Lee
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | - Eun Bae Kim
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea
| | - Roderick T Bronson
- Rodent Histopathology Laboratory, Harvard Medical School, Boston, MA 02115, USA
| | - Radim Šumbera
- University of South Bohemia, Faculty of Science, Ceske Budejovice 37005, Czech Republic
| | - Rochelle Buffenstein
- Department of Physiology and The Sam and Ann Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, TX 78245, USA
| | - Xin Zhou
- BGI-Shenzhen, Shenzhen 518083, China
| | - Anders Krogh
- Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Thomas J Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Guojie Zhang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark
| | - Jun Wang
- BGI-Shenzhen, Shenzhen 518083, China; Department of Biology, University of Copenhagen, Copenhagen, 2200 Copenhagen N, Denmark; King Abdulaziz University, Jeddah 21441, Saudi Arabia.
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA; Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, South Korea.
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Zhang C, Cao S, Toole BP, Xu Y. Cancer may be a pathway to cell survival under persistent hypoxia and elevated ROS: a model for solid-cancer initiation and early development. Int J Cancer 2014; 136:2001-11. [PMID: 24828886 DOI: 10.1002/ijc.28975] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 05/05/2014] [Indexed: 12/20/2022]
Abstract
A number of proposals have been made in the past century regarding what may drive sporadic cancers to initiate and develop. Yet the problem remains largely unsolved as none of the proposals have been widely accepted as cancer-initiation drivers. We propose here a driver model for the initiation and early development of solid cancers associated with inflammation-induced chronic hypoxia and reactive oxygen species (ROS) accumulation. The model consists of five key elements: (i)human cells tend to have a substantial gap between ATP demand and supply during chronic hypoxia, which would inevitably lead to increased uptake of glucose and accumulation of its metabolites; (ii) the accumulation of these metabolites will cast mounting pressure on the cells and ultimately result in the production and export of hyaluronic acid; (iii) the exported hyaluronic acid will be degraded into fragments of various sizes, serving as tissue-repair signals, including signals for cell proliferation, cell survival and angiogenesis, which lead to the initial proliferation of the underlying cells; (iv) cell division provides an exit for the accumulated glucose metabolites using them towards macromolecular synthesis for the new cell, and hence alleviate the pressure from the metabolite accumulation; and (v) this process continues as long as the hypoxic condition persists. In tandem, genetic mutations may be selected to make cell divisions and hence survival more sustainable and efficient, also increasingly more uncontrollable. This model also applies to some hereditary cancers as their key mutations, such as BRCA for breast cancer, generally lead to increased ROS and ultimately to repression of mitochondrial activities and up-regulation of glycolysis, as well as hypoxia; hence the energy gap, glucose-metabolite accumulation, hyaluronic acid production and continuous cell division for survival.
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Affiliation(s)
- Chi Zhang
- Computational Systems Biology Laboratory, Department of Biochemistry and Molecular Biology and Institute of Bioinformatics, University of Georgia, Athens, GA
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Amrein I, Becker AS, Engler S, Huang SH, Müller J, Slomianka L, Oosthuizen MK. Adult neurogenesis and its anatomical context in the hippocampus of three mole-rat species. Front Neuroanat 2014; 8:39. [PMID: 24904308 PMCID: PMC4033039 DOI: 10.3389/fnana.2014.00039] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 04/30/2014] [Indexed: 12/03/2022] Open
Abstract
African mole-rats (family Bathyergidae) are small to medium sized, long-lived, and strictly subterranean rodents that became valuable animal models as a result of their longevity and diversity in social organization. The formation and integration of new hippocampal neurons in adult mammals (adult hippocampal neurogenesis, AHN) correlates negatively with age and positively with habitat complexity. Here we present quantitative data on AHN in wild-derived mole-rats of 1 year and older, and briefly describe its anatomical context including markers of neuronal function (calbindin and parvalbumin). Solitary Cape mole-rats (Georychus capensis), social highveld mole-rats (Cryptomys hottentotus pretoriae), and eusocial naked mole-rats (Heterocephalus glaber) were assessed. Compared to other rodents, the hippocampal formation in mole-rats is small, but shows a distinct cytoarchitecture in the dentate gyrus and CA1. Distributions of the calcium-binding proteins differ from those seen in rodents; e.g., calbindin in CA3 of naked mole-rats distributes similar to the pattern seen in early primate development, and calbindin staining extends into the stratum lacunosum-moleculare of Cape mole-rats. Proliferating cells and young neurons are found in low numbers in the hippocampus of all three mole-rat species. Resident granule cell numbers are low as well. Proliferating cells expressed as a percentage of resident granule cells are in the range of other rodents, while the percentage of young neurons is lower than that observed in surface dwelling rodents. Between mole-rat species, we observed no difference in the percentage of proliferating cells. The percentages of young neurons are high in social highveld and naked mole-rats, and low in solitary Cape mole-rats. The findings support that proliferation is regulated independently of average life expectancy and habitat. Instead, neuronal differentiation reflects species-specific demands, which appear lower in subterranean rodents.
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Affiliation(s)
- Irmgard Amrein
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Anton S. Becker
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Stefanie Engler
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Shih-hui Huang
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Julian Müller
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Lutz Slomianka
- Division of Functional Neuroanatomy, Institute of Anatomy, University of ZürichZürich, Switzerland
| | - Maria K. Oosthuizen
- Department of Zoology and Entomology, University of PretoriaPretoria, South Africa
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Grimes KM, Voorhees A, Chiao YA, Han HC, Lindsey ML, Buffenstein R. Cardiac function of the naked mole-rat: ecophysiological responses to working underground. Am J Physiol Heart Circ Physiol 2014; 306:H730-7. [PMID: 24363308 PMCID: PMC3949069 DOI: 10.1152/ajpheart.00831.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/18/2013] [Indexed: 11/22/2022]
Abstract
The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm(2)) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.
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Affiliation(s)
- Kelly M Grimes
- Department of Physiology and the Sam and Ann Barshop Institute for Aging and Longevity Studies, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
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Edrey YH, Oddo S, Cornelius C, Caccamo A, Calabrese V, Buffenstein R. Oxidative damage and amyloid-β metabolism in brain regions of the longest-lived rodents. J Neurosci Res 2013; 92:195-205. [PMID: 24273049 DOI: 10.1002/jnr.23320] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/08/2013] [Accepted: 10/10/2013] [Indexed: 12/16/2022]
Abstract
Naked mole rats (NMRs) are the longest-lived rodents, with young individuals having high levels of Aβ in their brains. The purpose of this study was twofold: to assess the distribution of Aβ in key regions of NMR brains (cortex, hippocampus, cerebellum) and to understand whether the accumulation of Aβ is due to enhanced production or decreased degradation. Recent evidence indicates that lipid peroxides directly participate in induction of cytoprotective proteins, such as heat shock proteins (Hsps), which play a central role in the cellular mechanisms of stress tolerance. Amyloid precursor protein processing, lipid peroxidation, Hsps, redox status, and protein degradation processes were therefore assessed in key NMR brain regions. NMR brains had high levels of lipid peroxidation compared with mice, and the NMR hippocampus had the highest levels of the most toxic moiety of Aβ (soluble Aβ1 - 42 ). This was due not to increased Aβ production but rather to low antioxidant potential, which was associated with low induction of Hsp70 and heme oxygenase-1 as well as low ubiquitin-proteasome activity. NMRs may therefore serve as natural models for understanding the relationship between oxidative stress and Aβ levels and its effects on the brain.
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Affiliation(s)
- Yael H Edrey
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas; The Barshop Institute for Aging and Longevity Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas
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Animal Models and Better Understanding of “One Medicine”. Vet Sci 2013. [DOI: 10.3390/vetsci1010003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Yang Z, Zhang Y, Chen L. Investigation of anti-cancer mechanisms by comparative analysis of naked mole rat and rat. BMC SYSTEMS BIOLOGY 2013; 7 Suppl 2:S5. [PMID: 24565050 PMCID: PMC3852044 DOI: 10.1186/1752-0509-7-s2-s5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Background The naked mole rats (NMRs) are small-sized underground rodents with plenty of unusual traits. Their life expectancy can be up to thirty years, more than seven times longer than laboratory rat. Furthermore, they are resistant to both congenital and experimentally induced cancer genesis. These peculiar physiological and pathological characteristics allow them to become a suitable model for cancer and aging research. Results In this paper, we carried out a genome-wide comparative analysis of rat and NMR using the recently published genome sequence of NMR. First, we identified all the rat-NMR orthologous genes and specific genes within each of them. The expanded and contracted numbers of protein families in NMR were also analyzed when compared to rat. Seven cancer-related protein families appeared to be significantly expanded, whereas several receptor families were found to be contracted in NMR. We then chose those rat genes that were inexistent in NMR and adopted KEGG pathway database to investigate the metabolic processes in which their proteins may be involved. These genes were significantly enriched in two rat cancer pathways, "Pathway in cancer" and "Bladder cancer". In the rat "Pathway in cancer", 9 out of 14 paths leading to evading apoptosis appeared to be affected in NMR. In addition, a significant number of other NMR-missing genes enriched in several cancer-related pathways have been known to be related to a variety of cancers, implying that many of them may be also related to tumorigenesis in mammals. Finally, investigation of sequence variations among orthologous proteins between rat and NMR revealed that significant fragment insertions/deletions within important functional domains were present in some NMR proteins, which might lead to expressional and/or functional changes of these genes in different species. Conclusions Overall, this study provides insights into understanding the possible anti-cancer mechanisms of NMR as well as searching for new cancer-related candidate genes.
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Nathaniel TI, Otukonyong EE, Okon M, Chaves J, Cochran T, Nathaniel AI. Metabolic regulatory clues from the naked mole rat: toward brain regulatory functions during stroke. Brain Res Bull 2013; 98:44-52. [PMID: 23886571 DOI: 10.1016/j.brainresbull.2013.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 07/03/2013] [Accepted: 07/15/2013] [Indexed: 12/30/2022]
Abstract
Resistance to tissue hypoxia is a robust fundamental adaptation to low oxygen supply, and represents a novel neuroscience problem with significance to mammalian physiology as well as human health. With the underlying mechanisms strongly conserved in evolution, the ability to resist tissue hypoxia in natural systems has recently emerged as an interesting model in mammalian physiology research to understand mechanisms that can be manipulated for the clinical management of stroke. The extraordinary ability to resist tissue hypoxia by the naked mole rat (NMR) indicates the presence of a unique mechanism that underlies the remarkable healthy life span and exceptional hypoxia resistance. This opens an interesting line of research into understanding the mechanisms employed by the naked mole rat (Heterocephalus glaber) to protect the brain during hypoxia. In a series of studies, we first examined the presence of neuroprotection in the brain cells of naked mole rats (NMRs) subjected to hypoxic insults, and then characterized the expression of such neuroprotection in a wide range of time intervals. We used oxygen nutrient deprivation (OND), an in vitro model of resistance to tissue hypoxia to determine whether there is evidence of neuronal survival in the hippocampal (CA1) slices of NMRs that are subjected to chronic hypoxia. Hippocampus neurons of NMRs that were kept in hypoxic condition consistently tolerated OND right from the onset time of 5h. This tolerance was maintained for 24h. This finding indicates that there is evidence of resistance to tissue hypoxia by CA1 neurons of NMRs. We further examined the effect of hypoxia on metabolic rate in the NMR. Repeated measurement of metabolic rates during exposure of naked mole rats to hypoxia over a constant ambient temperature indicates that hypoxia significantly decreased metabolic rates in the NMR, suggesting that the observed decline in metabolic rate during hypoxia may contribute to the adaptive mechanism used by the NMR to resist tissue hypoxia. This work is aimed to contribute to the understanding of mechanisms of resistance to tissue hypoxia in the NMR as an important life-sustaining process, which can be translated into therapeutic interventions during stroke.
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Affiliation(s)
- Thomas I Nathaniel
- University of South Carolina School of Medicine, HSEB, 607 Grove Road, Greenville, SC 29605, United States.
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Edrey YH, Medina DX, Gaczynska M, Osmulski PA, Oddo S, Caccamo A, Buffenstein R. Amyloid beta and the longest-lived rodent: the naked mole-rat as a model for natural protection from Alzheimer's disease. Neurobiol Aging 2013; 34:2352-60. [PMID: 23618870 DOI: 10.1016/j.neurobiolaging.2013.03.032] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 03/14/2013] [Accepted: 03/27/2013] [Indexed: 01/09/2023]
Abstract
Amyloid beta (Aβ) is implicated in Alzheimer's disease (AD) as an integral component of both neural toxicity and plaque formation. Brains of the longest-lived rodents, naked mole-rats (NMRs) approximately 32 years of age, had levels of Aβ similar to those of the 3xTg-AD mouse model of AD. Interestingly, there was no evidence of extracellular plaques, nor was there an age-related increase in Aβ levels in the individuals examined (2-20+ years). The NMR Aβ peptide showed greater homology to the human sequence than to the mouse sequence, differing by only 1 amino acid from the former. This subtle difference led to interspecies differences in aggregation propensity but not neurotoxicity; NMR Aβ was less prone to aggregation than human Aβ. Nevertheless, both NMR and human Aβ were equally toxic to mouse hippocampal neurons, suggesting that Aβ neurotoxicity and aggregation properties were not coupled. Understanding how NMRs acquire and tolerate high levels of Aβ with no plaque formation could provide useful insights into AD, and may elucidate protective mechanisms that delay AD progression.
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Affiliation(s)
- Yael H Edrey
- Department of Physiology, University of Texas Health Science Center, San Antonio, TX 78229, USA
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St John Smith E, Purfürst B, Grigoryan T, Park TJ, Bennett NC, Lewin GR. Specific paucity of unmyelinated C-fibers in cutaneous peripheral nerves of the African naked-mole rat: comparative analysis using six species of Bathyergidae. J Comp Neurol 2013; 520:2785-803. [PMID: 22528859 PMCID: PMC3410526 DOI: 10.1002/cne.23133] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In mammalian peripheral nerves, unmyelinated C-fibers usually outnumber myelinated A-fibers. By using transmission electron microscopy, we recently showed that the saphenous nerve of the naked mole-rat (Heterocephalus glaber) has a C-fiber deficit manifested as a substantially lower C:A-fiber ratio compared with other mammals. Here we determined the uniqueness of this C-fiber deficit by performing a quantitative anatomical analysis of several peripheral nerves in five further members of the Bathyergidae mole-rat family: silvery (Heliophobius argenteocinereus), giant (Fukomys mechowii), Damaraland (Fukomys damarensis), Mashona (Fukomys darlingi), and Natal (Cryptomys hottentotus natalensis) mole-rats. In the largely cutaneous saphenous and sural nerves, the naked mole-rat had the lowest C:A-fiber ratio (∼1.5:1 compared with ∼3:1), whereas, in nerves innervating both skin and muscle (common peroneal and tibial) or just muscle (lateral/medial gastrocnemius), this pattern was mostly absent. We asked whether lack of hair follicles alone accounts for the C-fiber paucity by using as a model a mouse that loses virtually all its hair as a consequence of conditional deletion of the β-catenin gene in the skin. These β-catenin loss-of function mice (β-cat LOF mice) displayed only a mild decrease in C:A-fiber ratio compared with wild-type mice (4.42 compared with 3.81). We suggest that the selective cutaneous C-fiber deficit in the cutaneous nerves of naked mole-rats is unlikely to be due primarily to lack of skin hair follicles. Possible mechanisms contributing to this unique peripheral nerve anatomy are discussed.
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Affiliation(s)
- Ewan St John Smith
- Department of Neuroscience, Max-Delbrück Center for Molecular Medicine, D 13125 Berlin, Germany
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Gesing A, Lewiński A, Karbownik-Lewińska M. The thyroid gland and the process of aging; what is new? Thyroid Res 2012; 5:16. [PMID: 23176389 PMCID: PMC3526560 DOI: 10.1186/1756-6614-5-16] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 11/18/2012] [Indexed: 01/07/2023] Open
Abstract
The endocrine system and particular endocrine organs, including the thyroid, undergo important functional changes during aging. The prevalence of thyroid disorders increases with age and numerous morphological and physiological changes of the thyroid gland during the process of aging are well-known. It is to be stressed that the clinical course of thyroid diseases in the elderly differs essentially from that observed in younger individuals, because symptoms are more subtle and are often attributed to normal aging. Subclinical hypo- and hyperthyroidism, as well as thyroid neoplasms, require special attention in elderly subjects. Intriguingly, decreased thyroid function, as well as thyrotropin (TSH) levels - progressively shifting to higher values with age - may contribute to the increased lifespan.This short review focuses on recent findings concerning the alterations in thyroid function during aging, including these which may potentially lead to extended longevity, both in humans and animals.
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Affiliation(s)
- Adam Gesing
- Department of Oncological Endocrinology, Medical University of Lodz, Zeligowski St,, No, 7/9, Lodz, 90-752, Poland.
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Grimes KM, Lindsey ML, Gelfond JAL, Buffenstein R. Getting to the heart of the matter: age-related changes in diastolic heart function in the longest-lived rodent, the naked mole rat. J Gerontol A Biol Sci Med Sci 2012; 67:384-94. [PMID: 22367435 PMCID: PMC3309875 DOI: 10.1093/gerona/glr222] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The naked mole rat is an extremely long-lived (>31 years) small (35 g) rodent. Moreover, it maintains good health for most of its long life. We hypothesized that naked mole rats also show attenuated cardiac aging. With age, cardiac muscle can become less compliant, causing a decline in early diastolic filling (E) and a compensatory increase in atrial contraction-induced late filling (A). This results in decreased left ventricular E/A ratio. Doppler imaging showed no significant differences in E/A ratios (p = .48) among old (18-20 years) breeders and nonbreeders despite differences in estrogen levels. A cross-sectional study of 1- to 20-year-old naked mole rats (n = 76) revealed that E/A ratios declined with age in females (n = 40; p = .002) but not in males (n = 36; p = 0.45). Despite this, neither gender shows increased morbidity or mortality with age. These findings suggest that, notwithstanding the previously observed high lipid peroxidation in heart tissue, NMRs must possess mechanisms to stave off progression to fatal cardiac disease.
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Affiliation(s)
- Kelly M. Grimes
- Department of Physiology, Sam and Ann Barshop Institute for Aging and Longevity Studies
- Department of Cell and Structural Biology
| | - Merry L. Lindsey
- Department of Physiology, Sam and Ann Barshop Institute for Aging and Longevity Studies
- Department of Medicine
| | - Jonathan A. L. Gelfond
- Department of Physiology
- Department of Epidemiology and Biostatistics, University of Texas Health Science Center at San Antonio
| | - Rochelle Buffenstein
- Department of Physiology, Sam and Ann Barshop Institute for Aging and Longevity Studies
- Department of Cell and Structural Biology
- Department of Physiology
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Edrey YH, Casper D, Huchon D, Mele J, Gelfond JA, Kristan DM, Nevo E, Buffenstein R. Sustained high levels of neuregulin-1 in the longest-lived rodents; a key determinant of rodent longevity. Aging Cell 2012; 11:213-22. [PMID: 22103690 DOI: 10.1111/j.1474-9726.2011.00772.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Naked mole-rats (Heterocephalus glaber), the longest-lived rodents, live 7-10 times longer than similarly sized mice and exhibit normal activities for approximately 75% of their lives. Little is known about the mechanisms that allow them to delay the aging process and live so long. Neuregulin-1 (NRG-1) signaling is critical for normal brain function during both development and adulthood. We hypothesized that long-lived species will maintain higher levels of NRG-1 and that this contributes to their sustained brain function and concomitant maintenance of normal activity. We monitored the levels of NRG-1 and its receptor ErbB4 in H. glaber at different ages ranging from 1 day to 26 years and found that levels of NRG-1 and ErbB4 were sustained throughout development and adulthood. In addition, we compared seven rodent species with widely divergent (4-32 year) maximum lifespan potential (MLSP) and found that at a physiologically equivalent age, the longer-lived rodents had higher levels of NRG-1 and ErbB4. Moreover, phylogenetic independent contrast analyses revealed that this significant strong correlation between MLSP and NRG-1 levels was independent of phylogeny. These results suggest that NRG-1 is an important factor contributing to divergent species MLSP through its role in maintaining neuronal integrity.
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Affiliation(s)
- Yael H Edrey
- Department of Biology, The City College of New York, New York, NY 10031, USA
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