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Zeng J, Liu J, Ni H, Zhang L, Wang J, Li Y, Jiang W, Wu Z, Zhou M. Mitochondrial transplantation reduces lower limb ischemia-reperfusion injury by increasing skeletal muscle energy and adipocyte browning. Mol Ther Methods Clin Dev 2023; 31:101152. [PMID: 38027061 PMCID: PMC10667789 DOI: 10.1016/j.omtm.2023.101152] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 11/03/2023] [Indexed: 12/01/2023]
Abstract
Recent studies have shown that mitochondrial transplantation can repair lower limb IRI, but the underlying mechanism of the repair effect remains unclear. In this study, we found that in addition to being taken up by skeletal muscle cells, human umbilical cord mesenchymal stem cells (hMSCs)-derived mitochondria were also taken up by adipocytes, which was accompanied by an increase in optic atrophy 1 (OPA1) and uncoupling protein 1. Transplantation of hMSCs-derived mitochondria could not only supplement the original damaged mitochondrial function of skeletal muscle, but also promote adipocyte browning by increasing the expression of OPA1. In this process, mitochondrial transplantation can reduce cell apoptosis and repair muscle tissue, which promotes the recovery of motor function in vivo. To the best of our knowledge, there is no study on the therapeutic mechanism of mitochondrial transplantation from this perspective, which could provide a theoretical basis.
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Affiliation(s)
- Jiaqi Zeng
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
- Department of Vascular Surgery, Kunshan Traditional Chinese Medicine Hospital, Kunshan 215300, China
| | - Jianing Liu
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
| | - Haiya Ni
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
| | - Ling Zhang
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
| | - Jun Wang
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
| | - Yazhou Li
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
| | - Wentao Jiang
- Department of Vascular Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Ziyu Wu
- Department of Vascular Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Min Zhou
- Department of Vascular Surgery, Nanjing Drum Tower Hospital Clinical College of Nanjing University of Chinese Medicine, Nanjing 210046, China
- Department of Vascular Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China
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Fratantonio D, Cimino F, Speciale A, Virgili F. Need (more than) two to Tango: Multiple tools to adapt to changes in oxygen availability. Biofactors 2018; 44:207-218. [PMID: 29485192 DOI: 10.1002/biof.1419] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/11/2018] [Accepted: 01/25/2018] [Indexed: 12/13/2022]
Abstract
Oxygen is a fundamental element for the life of a large number of living organisms allowing an efficient energetic utilization of substrates. Organisms relying on oxygen evolved complex structures for oxygen delivery and biochemical machineries dealing with its safe utilization and the ability to overcome the potentially harmful consequences of changes in oxygen availability. On fact, cells composing complex Eukaryotic organisms are set to live within an optimum narrow range of oxygen, quite specific for each cell type. Minute modifications of oxygen availability, either positive or negative, induce the expression of specific genes, the major actors of this responses being the transcription factors HIF and Nrf2 that control the attempt to cope with low oxygen (hypoxia) or to either high oxygen or to an oxygen "overflow," respectively. This review describes the interaction between these two transcription factors and their interaction with the transcription factor NF-κB acting as a pivotal determinant of final cell response. © 2018 BioFactors, 44(3):207-218, 2018.
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Affiliation(s)
- Deborah Fratantonio
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Francesco Cimino
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Antonio Speciale
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Fabio Virgili
- Council for Agricultural Research and Economics-Food and Nutrition Research Centre (CREA-AN), Rome, Italy
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Kolamunne RT, Dias IHK, Vernallis AB, Grant MM, Griffiths HR. Nrf2 activation supports cell survival during hypoxia and hypoxia/reoxygenation in cardiomyoblasts; the roles of reactive oxygen and nitrogen species. Redox Biol 2013; 1:418-26. [PMID: 24191235 PMCID: PMC3814985 DOI: 10.1016/j.redox.2013.08.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/07/2013] [Accepted: 08/09/2013] [Indexed: 02/06/2023] Open
Abstract
Adaptive mechanisms involving upregulation of cytoprotective genes under the control of transcription factors such as Nrf2 exist to protect cells from permanent damage and dysfunction under stress conditions. Here we explore of the hypothesis that Nrf2 activation by reactive oxygen and nitrogen species modulates cytotoxicity during hypoxia (H) with and without reoxygenation (H/R) in H9C2 cardiomyoblasts. Using MnTBap as a cell permeable superoxide dismutase (SOD) mimetic and peroxynitrite scavenger and L-NAME as an inhibitor of nitric oxide synthase (NOS), we have shown that MnTBap inhibited the cytotoxic effects of hypoxic stress with and without reoxygenation. However, L-NAME only afforded protection during H. Under reoxygenation, conditions, cytotoxicity was increased by the presence of L-NAME. Nrf2 activation was inhibited independently by MnTBap and L-NAME under H and H/R. The increased cytotoxicity and inhibition of Nrf2 activation by the presence of L-NAME during reoxygenation suggests that NOS activity plays an important role in cell survival at least in part via Nrf2-independent pathways. In contrast, O2−• scavenging by MnTBap prevented both toxicity and Nrf2 activation during H and H/R implying that toxicity is largely dependent on O2−•.To confirm the importance of Nrf2 for myoblast metabolism, Nrf2 knockdown with siRNA reduced cell survival by 50% during 4 h hypoxia with and without 2 h of reoxygenation and although cellular glutathione (GSH) was depleted during H and H/R, GSH loss was not exacerbated by Nrf2 knockdown. These data support distinctive roles for ROS and RNS during H and H/R for Nrf2 induction which are important for survival independently of GSH salvage. Cardiomyoblast toxicity during hypoxia is dependent on O2−• and NO•. Nrf2 activation is important for cardiomyoblast survival during hypoxia or hypoxia/reoxygenation, but, restoration of GSH is not required. NOS activity is essential for the adaptation of cardiomyoblasts to hypoxia/reoxygenation but survival may be independent of Nrf2.
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Key Words
- Adaptive
- CREB, cAMP-responsive element-binding protein
- DAF-2-DA, 4,5-diaminofluorescein diacetate
- DHE, dihydroethidium
- Glutathione
- HIF-1, hypoxia-inducible factor
- KEAP1, Kelch-like ECH-associated protein 1
- L-NAME
- L-NAME, L-NG-nitroarginine methyl ester
- MnTBap
- MnTBap, manganese [III] tetrakis (4-benzoic acid) porphyrin
- NFκB, nuclear factor kappa B
- NO, nitric oxide
- NOS, nitric oxide synthase
- NOX, NADPH oxidase
- Nrf2, nuclear factor erythroid 2-related factor 2
- RNS
- RNS, reactive nitrogen species
- ROS
- ROS, reactive oxygen species
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Affiliation(s)
- Rajitha T Kolamunne
- Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK ; Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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Baracca A, Sgarbi G, Padula A, Solaini G. Glucose plays a main role in human fibroblasts adaptation to hypoxia. Int J Biochem Cell Biol 2013; 45:1356-65. [DOI: 10.1016/j.biocel.2013.03.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/01/2013] [Accepted: 03/12/2013] [Indexed: 01/22/2023]
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Mo L, Wang Y, Geary L, Corey C, Alef MJ, Beer-Stolz D, Zuckerbraun BS, Shiva S. Nitrite activates AMP kinase to stimulate mitochondrial biogenesis independent of soluble guanylate cyclase. Free Radic Biol Med 2012; 53:1440-50. [PMID: 22892143 PMCID: PMC3477807 DOI: 10.1016/j.freeradbiomed.2012.07.080] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 07/20/2012] [Accepted: 07/30/2012] [Indexed: 01/19/2023]
Abstract
Nitrite, a dietary constituent and endogenous signaling molecule, mediates a number of physiological responses including modulation of ischemia/reperfusion injury, glucose tolerance, and vascular remodeling. Although the exact molecular mechanisms underlying nitrite's actions are unknown, the current paradigm suggests that these effects depend on the hypoxic reduction of nitrite to nitric oxide (NO). Mitochondrial biogenesis is a fundamental mechanism of cellular adaptation and repair. However, the effect of nitrite on mitochondrial number has not been explored. Herein, we report that nitrite stimulates mitochondrial biogenesis through a mechanism distinct from that of NO. We demonstrate that nitrite significantly increases cellular mitochondrial number by augmenting the activity of adenylate kinase, resulting in AMP kinase phosphorylation, downstream activation of sirtuin-1, and deacetylation of PGC1α, the master regulator of mitochondrial biogenesis. Unlike NO, nitrite-mediated biogenesis does not require the activation of soluble guanylate cyclase and results in the synthesis of more functionally efficient mitochondria. Further, we provide evidence that nitrite mediates biogenesis in vivo. In a rat model of carotid injury, 2 weeks of continuous oral nitrite treatment postinjury prevented the hyperproliferative response of smooth muscle cells. This protection was accompanied by a nitrite-dependent upregulation of PGC1α and increased mitochondrial number in the injured artery. These data are the first to demonstrate that nitrite mediates differential signaling compared to NO. They show that nitrite is a versatile regulator of mitochondrial function and number both in vivo and in vitro and suggest that nitrite-mediated biogenesis may play a protective role in the setting of vascular injury.
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Affiliation(s)
- Li Mo
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Yinna Wang
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Lisa Geary
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Catherine Corey
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Matthew J. Alef
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Donna Beer-Stolz
- Center for Biological Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Brian S. Zuckerbraun
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Sruti Shiva
- Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Corresponding Author: Department of Pharmacology & Chemical Biology Vascular Medicine Institute BST E1242 University of Pittsburgh Pittsburgh, PA 15261 Fax: (412) 648-3046 Tel: (412)383-5854
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6
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Ultrastructural modifications in the mitochondria of hypoxia-adapted Drosophila melanogaster. PLoS One 2012; 7:e45344. [PMID: 23028948 PMCID: PMC3446896 DOI: 10.1371/journal.pone.0045344] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 08/21/2012] [Indexed: 01/05/2023] Open
Abstract
Chronic hypoxia (CH) occurs under certain physiological or pathological conditions, including in people who reside at high altitude or suffer chronic cardiovascular or pulmonary diseases. As mitochondria are the predominant oxygen-consuming organelles to generate ATP through oxidative phosphorylation in cells, their responses, through structural or molecular modifications, to limited oxygen supply play an important role in the overall functional adaptation to hypoxia. Here, we report the adaptive mitochondrial ultrastructural modifications and the functional impacts in a recently generated hypoxia-adapted Drosophila melanogaster strain that survives severe, otherwise lethal, hypoxic conditions. Using electron tomography, we discovered increased mitochondrial volume density and cristae abundance, yet also cristae fragmentation and a unique honeycomb-like structure in the mitochondria of hypoxia-adapted flies. The homeostatic levels of adenylate and energy charge were similar between hypoxia-adapted and naïve control flies and the hypoxia-adapted flies remained active under severe hypoxia as quantified by negative geotaxis behavior. The equilibrium ATP level was lower in hypoxia-adapted flies than those of the naïve controls tested under severe hypoxia that inhibited the motion of control flies. Our results suggest that the structural rearrangement in the mitochondria of hypoxia-adapted flies may be an important adaptive mechanism that plays a critical role in preserving adenylate homeostasis and metabolism as well as muscle function under chronic hypoxic conditions.
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Abstract
We evaluated the effects of high-altitude hypoxic stress in the murine model. For this purpose, 36 CR-mice in group A were maintained at the altitude of 3,820 m for hypoxia-induced factor (HIF)-1α expression analysis by immunohistochemistry. The 36 Wistar rats in group B were maintained in low-pressure (400-420 kPa) oxygen chamber, and the effects of hypoxia on myocardial mitochondria were studied. In the 36 CR-mice of group C, plasma vascular endothelial growth factor (VEGF) levels were determined using strept-avidin-biotin complex/diaminobenzidine method after exposure to different altitudes/O(2)-concentrations. The data show that in experimental group A1, endothelin (ET)-1α concentrations gradually increased whereas HIF-1α expression in myocardial cells was higher (P < 0.01) than in control group A2. In rats of group B, the myocardial mitochondria numbers were reduced during the initial phase of acute stress response to hypoxia and cellular injury but, later, mitochondrial numbers were restored to normal values. In mice of experimental group C1, plasma VEGF concentrations increased under hypoxia, which were significantly higher (P < 0.01) than those of control group C2. We, therefore, concluded that high-altitude hypoxia: (i) induced HIF-1α expression; (ii) prompted adaptation/acclimatization after initial stress and cellular injury; and (iii) enhanced VEGF expression in murine.
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McCarthy J, Lochner A, Opie LH, Sack MN, Essop MF. PKCε promotes cardiac mitochondrial and metabolic adaptation to chronic hypobaric hypoxia by GSK3β inhibition. J Cell Physiol 2011; 226:2457-68. [PMID: 21660969 PMCID: PMC3411281 DOI: 10.1002/jcp.22592] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PKCε is central to cardioprotection. Sub-proteome analysis demonstrated co-localization of activated cardiac PKCε (aPKCε) with metabolic, mitochondrial, and cardioprotective modulators like hypoxia-inducible factor 1α (HIF-1α). aPKCε relocates to the mitochondrion, inactivating glycogen synthase kinase 3β (GSK3β) to modulate glycogen metabolism, hypertrophy and HIF-1α. However, there is no established mechanistic link between PKCε, p-GSK3β and HIF1-α. Here we hypothesized that cardiac-restricted aPKCε improves mitochondrial response to hypobaric hypoxia by altered substrate fuel selection via a GSK3β/HIF-1α-dependent mechanism. aPKCε and wild-type (WT) mice were exposed to 14 days of hypobaric hypoxia (45 kPa, 11% O(2)) and cardiac metabolism, functional parameters, p-GSK3β/HIF-1α expression, mitochondrial function and ultrastructure analyzed versus normoxic controls. Mitochondrial ADP-dependent respiration, ATP production and membrane potential were attenuated in hypoxic WT but maintained in hypoxic aPKCε mitochondria (P < 0.005, n = 8). Electron microscopy revealed a hypoxia-associated increase in mitochondrial number with ultrastructural disarray in WT versus aPKCε hearts. Concordantly, left ventricular work was diminished in hypoxic WT but not aPKCε mice (glucose only perfusions). However, addition of palmitate abrogated this (P < 0.05 vs. WT). aPKCε hearts displayed increased glucose utilization at baseline and with hypoxia. In parallel, p-GSK3β and HIF1-α peptide levels were increased in hypoxic aPKCε hearts versus WT. Our study demonstrates that modest, sustained PKCε activation blunts cardiac pathophysiologic responses usually observed in response to chronic hypoxia. Moreover, we propose that preferential glucose utilization by PKCε hearts is orchestrated by a p-GSK3β/HIF-1α-mediated mechanism, playing a crucial role to sustain contractile function in response to chronic hypobaric hypoxia.
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Affiliation(s)
- Joy McCarthy
- Hatter Institute for Cardiovascular Research, University of Cape Town Medical School, Cape Town, South Africa.
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9
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Kolamunne RT, Clare M, Griffiths HR. Mitochondrial superoxide anion radicals mediate induction of apoptosis in cardiac myoblasts exposed to chronic hypoxia. Arch Biochem Biophys 2010; 505:256-65. [PMID: 20971059 DOI: 10.1016/j.abb.2010.10.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 09/27/2010] [Accepted: 10/17/2010] [Indexed: 11/16/2022]
Abstract
Both reactive oxygen species (ROS) and ATP depletion may be significant in hypoxia-induced damage and death, either collectively or independently, with high energy requiring, metabolically active cells being the most susceptible to damage. We investigated the kinetics and effects of ROS production in cardiac myoblasts, H9C2 cells, under 2%, 10% and 21% O₂ in the presence or absence of apocynin, rotenone and carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone. H9C2 cells showed significant loss of viability within 30 min of culture at 2% oxygen which was not due to apoptosis, but was associated with an increase in protein oxidation. However, after 4 h, apoptosis induction was observed at 2% oxygen and also to a lesser extent at 10% oxygen; this was dependent on the levels of mitochondrial superoxide anion radicals determined using dihydroethidine. Hypoxia-induced ROS production and cell death could be rescued by the mitochondrial complex I inhibitor, rotenone, despite further depletion of ATP. In conclusion, a change to superoxide anion radical steady state level was not detectable after 30 min but was evident after 4 h of mild or severe hypoxia. Superoxide anion radicals from the mitochondrion and not ATP depletion is the major cause of apoptotic cell death in cardiac myoblasts under chronic, severe hypoxia.
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Colleoni F, Lattuada D, Garretto A, Massari M, Mandò C, Somigliana E, Cetin I. Maternal blood mitochondrial DNA content during normal and intrauterine growth restricted (IUGR) pregnancy. Am J Obstet Gynecol 2010; 203:365.e1-6. [PMID: 20619387 DOI: 10.1016/j.ajog.2010.05.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 05/04/2010] [Accepted: 05/18/2010] [Indexed: 01/14/2023]
Abstract
OBJECTIVE We investigated mitochondrial DNA (mtDNA) content in the maternal circulation of normal pregnancies of different gestational ages and in pregnancies complicated by intrauterine growth restriction (IUGR). STUDY DESIGN We examined 70 maternal blood samples: 13 nonpregnant women; 45 normal pregnancies, divided into the 3 trimesters; and 12 pregnancies complicated by IUGR. MtDNA content was determined by real-time quantitative polymerase chain reaction, using a genomic control and a target gene. RESULTS A highly significant progressive reduction in circulating mtDNA was observed in pregnant women of first, second, and third trimesters and compared to nonpregnant women (mean value: 237, 188, 144, and 283, respectively; P < .001). Moreover, mtDNA was significantly increased in women carrying IUGR fetuses compared to women with normal pregnancies (430 vs 144; P < .001). CONCLUSION MtDNA could provide new insight into the mechanisms that occur during physiological gestation. Furthermore, mtDNA content may help recognize the IUGR disease in pregnancy.
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Chatfield MWH, Kozak KH, Fitzpatrick BM, Tucker PK. Patterns of differential introgression in a salamander hybrid zone: inferences from genetic data and ecological niche modelling. Mol Ecol 2010; 19:4265-82. [PMID: 20819165 DOI: 10.1111/j.1365-294x.2010.04796.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Hybrid zones have yielded considerable insight into many evolutionary processes, including speciation and the maintenance of species boundaries. Presented here are analyses from a hybrid zone that occurs among three salamanders -Plethodon jordani, Plethodon metcalfi and Plethodon teyahalee- from the southern Appalachian Mountains. Using a novel statistical approach for analysis of non-clinal, multispecies hybrid zones, we examined spatial patterns of variation at four markers: single-nucleotide polymorphisms (SNPs) located in the mtDNA ND2 gene and the nuclear DNA ILF3 gene, and the morphological markers of red cheek pigmentation and white flecks. Concordance of the ILF3 marker and both morphological markers across four transects is observed. In three of the four transects, however, the pattern of mtDNA is discordant from all other markers, with a higher representation of P. metcalfi mtDNA in the northern and lower elevation localities than is expected given the ILF3 marker and morphology. To explore whether climate plays a role in the position of the hybrid zone, we created ecological niche models for P. jordani and P. metcalfi. Modelling results suggest that hybrid zone position is not determined by steep gradients in climatic suitability for either species. Instead, the hybrid zone lies in a climatically homogenous region that is broadly suitable for both P. jordani and P. metcalfi. We discuss various selective (natural selection associated with climate) and behavioural processes (sex-biased dispersal, asymmetric reproductive isolation) that might explain the discordance in the extent to which mtDNA and nuclear DNA and colour-pattern traits have moved across this hybrid zone.
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Affiliation(s)
- M W H Chatfield
- Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, Ann Arbor, MI 48109-1079 USABell Museum of Natural History and Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St Paul, MN 55108 USADepartment of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996-1610 USA
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12
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Edwards LM, Murray AJ, Tyler DJ, Kemp GJ, Holloway CJ, Robbins PA, Neubauer S, Levett D, Montgomery HE, Grocott MP, Clarke K. The effect of high-altitude on human skeletal muscle energetics: P-MRS results from the Caudwell Xtreme Everest expedition. PLoS One 2010; 5:e10681. [PMID: 20502713 PMCID: PMC2873292 DOI: 10.1371/journal.pone.0010681] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 04/23/2010] [Indexed: 01/28/2023] Open
Abstract
Many disease states are associated with regional or systemic hypoxia. The study of healthy individuals exposed to high-altitude hypoxia offers a way to explore hypoxic adaptation without the confounding effects of disease and therapeutic interventions. Using 31P magnetic resonance spectroscopy and imaging, we investigated skeletal muscle energetics and morphology after exposure to hypobaric hypoxia in seven altitude-naïve subjects (trekkers) and seven experienced climbers. The trekkers ascended to 5300 m while the climbers ascended above 7950 m. Before the study, climbers had better mitochondrial function (evidenced by shorter phosphocreatine recovery halftime) than trekkers: 16±1 vs. 22±2 s (mean ± SE, p<0.01). Climbers had higher resting [Pi] than trekkers before the expedition and resting [Pi] was raised across both groups on their return (PRE: 2.6±0.2 vs. POST: 3.0±0.2 mM, p<0.05). There was significant muscle atrophy post-CXE (PRE: 4.7±0.2 vs. POST: 4.5±0.2 cm2, p<0.05), yet exercising metabolites were unchanged. These results suggest that, in response to high altitude hypoxia, skeletal muscle function is maintained in humans, despite significant atrophy.
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Affiliation(s)
- Lindsay M Edwards
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, Oxfordshire, United Kingdom.
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Pagel-Langenickel I, Bao J, Pang L, Sack MN. The role of mitochondria in the pathophysiology of skeletal muscle insulin resistance. Endocr Rev 2010; 31:25-51. [PMID: 19861693 PMCID: PMC2852205 DOI: 10.1210/er.2009-0003] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 08/27/2009] [Indexed: 12/18/2022]
Abstract
Multiple organs contribute to the development of peripheral insulin resistance, with the major contributors being skeletal muscle, liver, and adipose tissue. Because insulin resistance usually precedes the development of type 2 diabetes mellitus (T2DM) by many years, understanding the pathophysiology of insulin resistance should enable development of therapeutic strategies to prevent disease progression. Some subjects with mitochondrial genomic variants/defects and a subset of lean individuals with hereditary predisposition to T2DM exhibit skeletal muscle mitochondrial dysfunction early in the course of insulin resistance. In contrast, in the majority of subjects with T2DM the plurality of evidence implicates skeletal muscle mitochondrial dysfunction as a consequence of perturbations associated with T2DM, and these mitochondrial deficits then contribute to subsequent disease progression. We review the affirmative and contrarian data regarding skeletal muscle mitochondrial biology in the pathogenesis of insulin resistance and explore potential therapeutic options to intrinsically modulate mitochondria as a strategy to combat insulin resistance. Furthermore, an overview of restricted molecular manipulations of skeletal muscle metabolic and mitochondrial biology offers insight into the mitochondrial role in metabolic substrate partitioning and in promoting innate adaptive and maladaptive responses that collectively regulate peripheral insulin sensitivity. We conclude that skeletal muscle mitochondrial dysfunction is not generally a major initiator of the pathophysiology of insulin resistance, although its dysfunction is integral to this pathophysiology and it remains an intriguing target to reverse/delay the progressive perturbations synonymous with T2DM.
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Affiliation(s)
- Ines Pagel-Langenickel
- Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, Maryland 20892-1454, USA
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14
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Balligand JL, Feron O, Dessy C. eNOS activation by physical forces: from short-term regulation of contraction to chronic remodeling of cardiovascular tissues. Physiol Rev 2009; 89:481-534. [PMID: 19342613 DOI: 10.1152/physrev.00042.2007] [Citation(s) in RCA: 315] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Nitric oxide production in response to flow-dependent shear forces applied on the surface of endothelial cells is a fundamental mechanism of regulation of vascular tone, peripheral resistance, and tissue perfusion. This implicates the concerted action of multiple upstream "mechanosensing" molecules reversibly assembled in signalosomes recruiting endothelial nitric oxide synthase (eNOS) in specific subcellular locales, e.g., plasmalemmal caveolae. Subsequent short- and long-term increases in activity and expression of eNOS translate this mechanical stimulus into enhanced NO production and bioactivity through a complex transcriptional and posttranslational regulation of the enzyme, including by shear-stress responsive transcription factors, oxidant stress-dependent regulation of transcript stability, eNOS regulatory phosphorylations, and protein-protein interactions. Notably, eNOS expressed in cardiac myocytes is amenable to a similar regulation in response to stretching of cardiac muscle cells and in part mediates the length-dependent increase in cardiac contraction force. In addition to short-term regulation of contractile tone, eNOS mediates key aspects of cardiac and vascular remodeling, e.g., by orchestrating the mobilization, recruitment, migration, and differentiation of cardiac and vascular progenitor cells, in part by regulating the stabilization and transcriptional activity of hypoxia inducible factor in normoxia and hypoxia. The continuum of the influence of eNOS in cardiovascular biology explains its growing implication in mechanosensitive aspects of integrated physiology, such as the control of blood pressure variability or the modulation of cardiac remodeling in situations of hemodynamic overload.
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Affiliation(s)
- J-L Balligand
- Unit of Pharmacology and Therapeutics, Université catholique de Louvain, Brussels, Belgium.
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Abstract
Hypoxia and its corollaries pose both negative and positive pressures to multicellular eukaryotes. Evolutionarily, life developed under hypoxia, and the building blocks were established under conditions close to anaerobiosis; therefore, reason exists to expect that certain biologic processes may perform preferentially under hypoxia. Evolving evidence suggests that by providing an environment of reduced oxidative stress, hypoxia may help preserve the biologic functions of some cells and prevent senescence. Hypoxia provides essential signals for development, trimming redundant tissue by inducing apoptosis and driving the growth and development of oxygen and nutrient delivery systems, as well as those for waste management. The pathologic consequences of hypoxia and ischemia, including acidosis and oxidative stress associated with hypoxia-reoxygenation, form the basis of most of the major diseases confronting humans, including heart disease, cancer, and age-related degenerative conditions. The 11 articles in the forum touch on multiple aspects of hypoxia, in particular, signaling responses, adaptations, and diseases that result from imbalance and fluctuations of supply and demand. Although we have developed elaborate processes to combat hypoxia and oxidative damage, it is clear that oxygen and our environment still control us, perhaps even more than they did our unicellular ancestors 2 billion years ago.
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16
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Abstract
Since a constant supply of oxygen is essential to sustain life, organisms have evolved multiple defence mechanisms to ensure maintenance of the delicate balance between oxygen supply and demand. However, this homeostatic balance is perturbed in response to a severe impairment of oxygen supply, thereby activating maladaptive signalling cascades that result in cardiac damage. Past research efforts have largely focused on determining the pathophysiological effects of severe lack of oxygen. By contrast, and as reviewed here, exposure to moderate chronic hypoxia may induce cardioprotective properties. The hypothesis put forward is that chronic hypoxia triggers regulatory pathways that mediate long-term cardiac metabolic remodelling, particularly at the transcriptional level. The novel proposal is that exposure to chronic hypoxia triggers (a) oxygen-sensitive transcriptional modulators that induce a switch to increased carbohydrate metabolism (fetal gene programme) and (b) enhanced mitochondrial respiratory capacity to sustain and increase efficiency of mitochondrial energy production. These compensatory protective mechanisms preserve contractile function despite hypoxia.
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Affiliation(s)
- M Faadiel Essop
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa.
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