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Protective effects of farnesyltransferase inhibitor on sepsis-induced morphological aberrations of mitochondria in muscle and increased circulating mitochondrial DNA levels in mice. Biochem Biophys Res Commun 2021; 556:93-98. [PMID: 33845310 PMCID: PMC8757346 DOI: 10.1016/j.bbrc.2021.03.141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/25/2022]
Abstract
Sepsis remains a leading cause of mortality in critically ill patients and is characterized by multi-organ dysfunction. Mitochondrial damage has been proposed to be involved in the pathophysiology of sepsis. In addition to metabolic impairments resulting from mitochondrial dysfunction, mitochondrial DNA (mtDNA) causes systemic inflammation as a damage-associated molecular pattern when it is released to the circulation. Metabolic derangements in skeletal muscle are a major complication of sepsis and negatively affects clinical outcomes of septic patients. However, limited knowledge is available about sepsis-induced mitochondrial damage in skeletal muscle. Here, we show that sepsis induced profound abnormalities in cristae structure, rupture of the inner and outer membranes and enlargement of the mitochondria in mouse skeletal muscle in a time-dependent manner, which was associated with increased plasma mtDNA levels. Farnesyltransferase inhibitor, FTI-277, prevented sepsis-induced morphological aberrations of the mitochondria, and blocked the increased plasma mtDNA levels along with improved survival. These results indicate that protein farnesylation plays a role in sepsis-induced damage of the mitochondria in mouse skeletal muscle. Our findings suggest that mitochondrial disintegrity in skeletal muscle may contribute to elevated circulating mtDNA levels in sepsis.
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Mikhaeil JS, Sacco SM, Saint C, Gittings W, Bunda J, Giles CR, Fajardo VA, Vandenboom R, Ward WE, LeBlanc PJ. Influence of longitudinal radiation exposure from microcomputed tomography scanning on skeletal muscle function and metabolic activity in female CD-1 mice. Physiol Rep 2017; 5:5/13/e13338. [PMID: 28676556 PMCID: PMC5506525 DOI: 10.14814/phy2.13338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 05/29/2017] [Accepted: 06/05/2017] [Indexed: 01/15/2023] Open
Abstract
Microcomputed tomography (μCT) is an imaging technology to assess bone microarchitecture, a determinant of bone strength. When measured in vivo, μCT exposes the skeletal site of interest to a dose of radiation, in addition to nearby skeletal muscles as well. Therefore, the aim of this study was to determine the effects of repeated radiation exposure from in vivo μCT on muscle health – specifically, muscle morphometrics, contractile function, and enzyme activity. This study exposed the right hind limb of female mice to either a low (26 cGy) or moderate (46 cGy) dose, at 2, 4, and 6 months of age, while the left hind limb of the same animal was exposed to a single dose at 6 months to serve as a nonirradiated control. Muscle weight, cross‐sectional area, isometric contractile function, and representative maximal enzyme activities of amino acid, fatty acid, glucose, and oxidative metabolism in extensor digitorum longus (EDL) and soleus were assessed. Low‐dose radiation had no effect. In contrast, moderate‐dose radiation resulted in a 5% increase in time‐to‐peak tension and 16% increase in half‐relaxation time of isometric twitches in EDL, although these changes were not seen when normalized to force. Moderate‐dose radiation also resulted in an ~33% decrease in citrate synthase activity in soleus but not EDL, with no changes to the other enzymes measured. Thus, three low doses of radiation over 6 months had no effect on contractile function or metabolic enzyme activity in soleus and EDL of female mice. In contrast, three moderate doses of radiation over 6 months induced some effects on metabolic enzyme activity in soleus but not EDL. Future studies that wish to investigate muscle tissue that is adjacent to scanned bone should take radiation exposure dose into consideration.
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Affiliation(s)
- John S Mikhaeil
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Sandra M Sacco
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Caitlin Saint
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - William Gittings
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Jordan Bunda
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Cameron R Giles
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Val A Fajardo
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Rene Vandenboom
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Wendy E Ward
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada.,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada.,Department of Kinesiology, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
| | - Paul J LeBlanc
- Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontaria, Canada .,Department of Health Sciences, Faculty of Applied Health Sciences, Brock University, St. Catharines, Ontaria, Canada
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Kam WWY, Banati RB. Effects of ionizing radiation on mitochondria. Free Radic Biol Med 2013; 65:607-619. [PMID: 23892359 DOI: 10.1016/j.freeradbiomed.2013.07.024] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 07/16/2013] [Accepted: 07/16/2013] [Indexed: 01/08/2023]
Abstract
The current concept of radiobiology posits that damage to the DNA in the cell nucleus is the primary cause for the detrimental effects of radiation. However, emerging experimental evidence suggests that this theoretical framework is insufficient for describing extranuclear radiation effects, particularly the response of the mitochondria, an important site of extranuclear, coding DNA. Here, we discuss experimental observations of the effects of ionizing radiation on the mitochondria at (1) the DNA and (2) functional levels. The roles of mitochondria in (3) oxidative stress and (4) late radiation effects are discussed. In this review, we summarize the current understanding of targets for ionizing radiation outside the cell nucleus. Available experimental data suggest that an increase in the tumoricidal efficacy of radiation therapy might be achievable by targeting mitochondria. Likewise, more specific protection of mitochondria and its coding DNA should reduce damage to healthy cells exposed to ionizing radiation.
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Affiliation(s)
- Winnie Wai-Ying Kam
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia.
| | - Richard B Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia; National Imaging Facility at Brain and Mind Research Institute (BMRI), University of Sydney, Camperdown, Sydney, New South Wales 2050, Australia
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Kam WWY, McNamara AL, Lake V, Banos C, Davies JB, Kuncic Z, Banati RB. Predicted ionisation in mitochondria and observed acute changes in the mitochondrial transcriptome after gamma irradiation: A Monte Carlo simulation and quantitative PCR study. Mitochondrion 2013; 13:736-42. [DOI: 10.1016/j.mito.2013.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/14/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
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Kam WWY, Lake V, Banos C, Davies J, Banati R. Apparent polyploidization after gamma irradiation: pitfalls in the use of quantitative polymerase chain reaction (qPCR) for the estimation of mitochondrial and nuclear DNA gene copy numbers. Int J Mol Sci 2013; 14:11544-59. [PMID: 23722662 PMCID: PMC3709747 DOI: 10.3390/ijms140611544] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/18/2013] [Accepted: 05/16/2013] [Indexed: 12/12/2022] Open
Abstract
Quantitative polymerase chain reaction (qPCR) has been widely used to quantify changes in gene copy numbers after radiation exposure. Here, we show that gamma irradiation ranging from 10 to 100 Gy of cells and cell-free DNA samples significantly affects the measured qPCR yield, due to radiation-induced fragmentation of the DNA template and, therefore, introduces errors into the estimation of gene copy numbers. The radiation-induced DNA fragmentation and, thus, measured qPCR yield varies with temperature not only in living cells, but also in isolated DNA irradiated under cell-free conditions. In summary, the variability in measured qPCR yield from irradiated samples introduces a significant error into the estimation of both mitochondrial and nuclear gene copy numbers and may give spurious evidence for polyploidization.
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Affiliation(s)
- Winnie W. Y. Kam
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia
- Author to whom correspondence should be addressed; E-Mail: or ; Tel.: +61-2-9717-7241; Fax: +61-2-9717-9262
| | - Vanessa Lake
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
| | - Connie Banos
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
| | - Justin Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- School of Physics, University of Sydney, Camperdown, Sydney, New South Wales 2006, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia
- National Imaging Facility at Brain and Mind Research Institute (BMRI), University of Sydney, Camperdown, Sydney, New South Wales 2050, Australia
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Green fluorescent protein alters the transcriptional regulation of human mitochondrial genes after gamma irradiation. J Fluoresc 2013; 23:613-9. [PMID: 23475276 DOI: 10.1007/s10895-013-1206-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/24/2013] [Indexed: 12/21/2022]
Abstract
Green fluorescent proteins (GFP), extensively used as reporters in biological and imaging studies, are assumed to be mostly biologically inert. Here, we test the assumption in regard to the transcriptional regulation of 18 mitochondrially encoded genes in GFP expressing human T-cell line (JURKAT cells) exposed to gamma radiation. Using quantitative polymerase chain reaction, we demonstrate that wild type and GFP expressing JURKAT cells have different baseline mitochondrial transcript expression (10 out of the 18 tested genes) and after a single dose of radiation (100 Gy) show a significantly different transcriptional regulation of their mitochondrial genes. While in wild type cells, ten of the tested genes are up-regulated in response to radiation exposure, GFP expressing cells show less transcriptional regulation with a small down-regulation in five genes. Our results indicate that the presence of GFP in the cytoplasm can alter the cellular response to ionizing radiation.
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Hoque R, Sohail M, Malik A, Sarwar S, Luo Y, Shah A, Barrat F, Flavell R, Gorelick F, Husain S, Mehal W. TLR9 and the NLRP3 inflammasome link acinar cell death with inflammation in acute pancreatitis. Gastroenterology 2011; 141:358-69. [PMID: 21439959 PMCID: PMC3129497 DOI: 10.1053/j.gastro.2011.03.041] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 03/02/2011] [Accepted: 03/08/2011] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Acute pancreatitis is characterized by early activation of intracellular proteases followed by acinar cell death and inflammation. Activation of damage-associated molecular pattern (DAMP) receptors and a cytosolic complex termed the inflammasome initiate forms of inflammation. In this study, we examined whether DAMP-receptors and the inflammasome provide the link between cell death and the initiation of inflammation in pancreatitis. METHODS Acute pancreatitis was induced by caerulein stimulation in wild-type mice and mice deficient in components of the inflammasome (apoptosis-associated speck-like protein containing a caspase recruitment domain [ASC], NLRP3, caspase-1), Toll-like receptor 9 (TLR9), or the purinergic receptor P2X(7). Resident and infiltrating immune cell populations and pro-interleukin-1β expression were characterized in control and caerulein-treated adult murine pancreas. TLR9 expression was quantified in pancreatic cell populations. Additionally, wild-type mice were pretreated with a TLR9 antagonist before induction of acute pancreatitis by caerulein or retrograde bile duct infusion of taurolithocholic acid 3-sulfate. RESULTS Caspase-1, ASC, and NLRP3 were required for inflammation in acute pancreatitis. Genetic deletion of Tlr9 reduced pancreatic edema, inflammation, and pro-IL-1β expression in pancreatitis. TLR9 was expressed in resident immune cells of the pancreas, which are predominantly macrophages. Pretreatment with the TLR9 antagonist IRS954 reduced pancreatic edema, inflammatory infiltrate, and apoptosis. Pretreatment with IRS954 reduced pancreatic necrosis and lung inflammation in taurolithocholic acid 3-sulfate-induced acute pancreatitis. CONCLUSIONS Components of the inflammasome, ASC, caspase-1, and NLRP3, are required for the development of inflammation in acute pancreatitis. TLR9 and P2X(7) are important DAMP receptors upstream of inflammasome activation, and their antagonism could provide a new therapeutic strategy for treating acute pancreatitis.
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Affiliation(s)
- Rafaz Hoque
- Section of Digestive Diseases, Yale University, New Haven, CT, USA
| | - Muhammad Sohail
- Section of Digestive Diseases, Yale University, New Haven, CT, USA
| | - Ahsan Malik
- Section of Digestive Diseases, Yale University, New Haven, CT, USA
| | - Sherhayar Sarwar
- Section of Gastroenterology, Department of Pediatrics, Yale University, New Haven, CT, USA
| | - Yuhuan Luo
- Section of Gastroenterology, Department of Pediatrics, Yale University, New Haven, CT, USA
| | - Ahsan Shah
- Section of Gastroenterology, Department of Pediatrics, Yale University, New Haven, CT, USA
| | - Franck Barrat
- Dynavax Technologies Corporation, Berkeley, CA 94710, USA
| | - Richard Flavell
- Department of Immunobiology, Yale University, New Haven, CT, USA
| | - Fred Gorelick
- Section of Digestive Diseases, Yale University, New Haven, CT, USA
| | - Sohail Husain
- Section of Gastroenterology, Department of Pediatrics, Yale University, New Haven, CT, USA
| | - Wajahat Mehal
- Section of Digestive Diseases, Yale University, New Haven, CT, USA
,Department of Immunobiology, Yale University, New Haven, CT, USA
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