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Antoun G, Tillocher T, Lefaucheux P, Faguet J, Maekawa K, Dussart R. Author Correction: Mechanism understanding in cryo atomic layer etching of SiO 2 based upon C 4F 8 physisorption. Sci Rep 2022; 12:1979. [PMID: 35105938 PMCID: PMC8807615 DOI: 10.1038/s41598-022-06291-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- G Antoun
- GREMI, Orléans University-CNRS, 14 Rue d'Issoudun, BP 6744, 45067, Orléans, France.
| | - T Tillocher
- GREMI, Orléans University-CNRS, 14 Rue d'Issoudun, BP 6744, 45067, Orléans, France
| | - P Lefaucheux
- GREMI, Orléans University-CNRS, 14 Rue d'Issoudun, BP 6744, 45067, Orléans, France
| | - J Faguet
- TEL Technology Center, America, LLC, NanoFab 300 South 255 Fuller Rd., Suite 214, Albany, NY, USA
| | - K Maekawa
- TEL Technology Center, America, LLC, NanoFab 300 South 255 Fuller Rd., Suite 214, Albany, NY, USA
| | - R Dussart
- GREMI, Orléans University-CNRS, 14 Rue d'Issoudun, BP 6744, 45067, Orléans, France.
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Patten DA, McGuirk S, Anilkumar U, Antoun G, Gandhi K, Parmar G, Iqbal MA, Wong J, Richardson RB, St-Pierre J, Slack RS, Harper ME. Altered mitochondrial fusion drives defensive glutathione synthesis in cells able to switch to glycolytic ATP production. Biochim Biophys Acta Mol Cell Res 2020; 1868:118854. [PMID: 32926942 DOI: 10.1016/j.bbamcr.2020.118854] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 01/05/2023]
Abstract
Mitochondria are highly dynamic organelles. Alterations in mitochondrial dynamics are causal or are linked to numerous neurodegenerative, neuromuscular, and metabolic diseases. It is generally thought that cells with altered mitochondrial structure are prone to mitochondrial dysfunction, increased reactive oxygen species generation and widespread oxidative damage. The objective of the current study was to investigate the relationship between mitochondrial dynamics and the master cellular antioxidant, glutathione (GSH). We reveal that mouse embryonic fibroblasts (MEFs) lacking the mitochondrial fusion machinery display elevated levels of GSH, which limits oxidative damage. Moreover, targeted metabolomics and 13C isotopic labeling experiments demonstrate that cells lacking the inner membrane fusion GTPase OPA1 undergo widespread metabolic remodeling altering the balance of citric acid cycle intermediates and ultimately favoring GSH synthesis. Interestingly, the GSH precursor and antioxidant n-acetylcysteine did not increase GSH levels in OPA1 KO cells, suggesting that cysteine is not limiting for GSH production in this context. Post-mitotic neurons were unable to increase GSH production in the absence of OPA1. Finally, the ability to use glycolysis for ATP production was a requirement for GSH accumulation following OPA1 deletion. Thus, our results demonstrate a novel role for mitochondrial fusion in the regulation of GSH synthesis, and suggest that cysteine availability is not limiting for GSH synthesis in conditions of mitochondrial fragmentation. These findings provide a possible explanation for the heightened sensitivity of certain cell types to alterations in mitochondrial dynamics.
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Affiliation(s)
- David A Patten
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada; Canadian Nuclear Laboratories (CNL), Radiobiology and Health Branch, Chalk River Laboratories, Chalk River, ON K0J 1J0, Canada; Ottawa Institute of Systems Biology, Ottawa K1H 8M5, Canada
| | - Shawn McGuirk
- McGill University, Department of Biochemistry, Montreal, QC H3G 1Y6, Canada
| | - Ujval Anilkumar
- University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, Ottawa, ON K1H 8M5, Canada
| | - Ghadi Antoun
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada
| | - Karan Gandhi
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada
| | - Gaganvir Parmar
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, Ottawa K1H 8M5, Canada
| | - Mohamed Ariff Iqbal
- University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, Ottawa, ON K1H 8M5, Canada
| | - Jacob Wong
- University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, Ottawa, ON K1H 8M5, Canada
| | - Richard B Richardson
- Canadian Nuclear Laboratories (CNL), Radiobiology and Health Branch, Chalk River Laboratories, Chalk River, ON K0J 1J0, Canada; McGill Medical Physics Unit, Cedars Cancer Centre - Glen Site, Montreal, QC H4A 3J1, Canada
| | - Julie St-Pierre
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, Ottawa K1H 8M5, Canada; McGill University, Department of Biochemistry, Montreal, QC H3G 1Y6, Canada
| | - Ruth S Slack
- University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, Ottawa, ON K1H 8M5, Canada.
| | - Mary-Ellen Harper
- University of Ottawa, Faculty of Medicine, Department of Biochemistry Microbiology and Immunology, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, Ottawa K1H 8M5, Canada.
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Vanstone JR, Smith AM, McBride S, Naas T, Holcik M, Antoun G, Harper ME, Michaud J, Sell E, Chakraborty P, Tetreault M, Majewski J, Baird S, Boycott KM, Dyment DA, MacKenzie A, Lines MA. DNM1L-related mitochondrial fission defect presenting as refractory epilepsy. Eur J Hum Genet 2016; 24:1084-8. [PMID: 26604000 PMCID: PMC5070894 DOI: 10.1038/ejhg.2015.243] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/02/2015] [Accepted: 10/14/2015] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial fission and fusion are dynamic processes vital to mitochondrial quality control and the maintenance of cellular respiration. In dividing mitochondria, membrane scission is accomplished by a dynamin-related GTPase, DNM1L, that oligomerizes at the site of fission and constricts in a GTP-dependent manner. There is only a single previous report of DNM1L-related clinical disease: a female neonate with encephalopathy due to defective mitochondrial and peroxisomal fission (EMPF; OMIM #614388), a lethal disorder characterized by cerebral dysgenesis, seizures, lactic acidosis, elevated very long chain fatty acids, and abnormally elongated mitochondria and peroxisomes. Here, we describe a second individual, diagnosed via whole-exome sequencing, who presented with developmental delay, refractory epilepsy, prolonged survival, and no evidence of mitochondrial or peroxisomal dysfunction on standard screening investigations in blood and urine. EEG was nonspecific, showing background slowing with frequent epileptiform activity at the frontal and central head regions. Electron microscopy of skeletal muscle showed subtle, nonspecific abnormalities of cristal organization, and confocal microscopy of patient fibroblasts showed striking hyperfusion of the mitochondrial network. A panel of further bioenergetic studies in patient fibroblasts showed no significant differences versus controls. The proband's de novo DNM1L variant, NM_012062.4:c.1085G>A; NP_036192.2:p.(Gly362Asp), falls within the middle (oligomerization) domain of DNM1L, implying a likely dominant-negative mechanism. This disorder, which presents nonspecifically and affords few diagnostic clues, can be diagnosed by means of DNM1L sequencing and/or confocal microscopy.
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Affiliation(s)
- Jason R Vanstone
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Amanda M Smith
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Skye McBride
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Turaya Naas
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Martin Holcik
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Ghadi Antoun
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jean Michaud
- Department of Pathology and Laboratory Medicine, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada
| | - Erick Sell
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Pranesh Chakraborty
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Martine Tetreault
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
| | - Care4Rare Consortium
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Jacek Majewski
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
| | - Stephen Baird
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Kym M Boycott
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - David A Dyment
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Alex MacKenzie
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
| | - Matthew A Lines
- Children's Hospital of Eastern Ontario Research Institute and University of Ottawa, Ottawa, Ontario, Canada
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Antoun G, McMurray F, Thrush AB, Patten DA, Peixoto AC, Slack RS, McPherson R, Dent R, Harper ME. Erratum to: Impaired mitochondrial oxidative phosphorylation and supercomplex assembly in rectus abdominis muscle of diabetic obese individuals. Diabetologia 2016; 59:396-7. [PMID: 26610932 DOI: 10.1007/s00125-015-3821-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Ghadi Antoun
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - Fiona McMurray
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - A Brianne Thrush
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - David A Patten
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Alyssa C Peixoto
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - Ruth S Slack
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ruth McPherson
- Atherogenomics Laboratory, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Robert Dent
- Ottawa Hospital Weight Management Clinic, The Ottawa Hospital, Ottawa, ON, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5.
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Antoun G, McMurray F, Thrush AB, Patten DA, Peixoto AC, Slack RS, McPherson R, Dent R, Harper ME. Impaired mitochondrial oxidative phosphorylation and supercomplex assembly in rectus abdominis muscle of diabetic obese individuals. Diabetologia 2015; 58:2861-6. [PMID: 26404066 DOI: 10.1007/s00125-015-3772-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/01/2015] [Indexed: 10/23/2022]
Abstract
AIMS/HYPOTHESIS Skeletal muscle mitochondrial dysfunction has been documented in patients with type 2 diabetes mellitus; however, specific respiratory defects and their mechanisms are poorly understood. The aim of the current study was to examine oxidative phosphorylation and electron transport chain (ETC) supercomplex assembly in rectus abdominis muscles of 10 obese diabetic and 10 obese non-diabetic individuals. METHODS Twenty obese women undergoing Roux-en-Y gastric bypass surgery were recruited for this study. Muscle samples were obtained intraoperatively and subdivided for multiple analyses, including high-resolution respirometry and assessment of supercomplex assembly. Clinical data obtained from referring physicians were correlated with laboratory findings. RESULTS Participants in both groups were of a similar age, weight and BMI. Mitochondrial respiration rates were markedly reduced in diabetic vs non-diabetic patients. This defect was observed during maximal ADP-stimulated respiration in the presence of complex I-linked substrates and complex I- and II-linked substrates, and during maximal uncoupled respiration. There were no differences in fatty acid (octanoyl carnitine) supported respiration, leak respiration or isolated activity of cytochrome c oxidase. Intriguingly, significant correlations were found between glycated haemoglobin (HbA1c) levels and maximal respiration or respiration supported by complex I, complex I and II or fatty acid. In the muscle of diabetic patients, blue native gel electrophoresis revealed a striking decrease in complex I, III and IV containing ETC supercomplexes. CONCLUSIONS/INTERPRETATION These findings support the hypothesis that ETC supercomplex assembly may be an important underlying mechanism of muscle mitochondrial dysfunction in type 2 diabetes mellitus.
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Affiliation(s)
- Ghadi Antoun
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - Fiona McMurray
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - A Brianne Thrush
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - David A Patten
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Alyssa C Peixoto
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5
| | - Ruth S Slack
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ruth McPherson
- Atherogenomics Laboratory, University of Ottawa Heart Institute, Ottawa, ON, Canada
| | - Robert Dent
- Ottawa Hospital Weight Management Clinic, The Ottawa Hospital, Ottawa, ON, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada, K1H 8M5.
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Antoun G, Keow J, Ram VD, Thornton C, Wang X, Yoon JY. Scientific overview: CSCI-CITAC Annual General Meeting and Young Investigator's Forum 2013. ACTA ACUST UNITED AC 2014; 37:E191-5. [PMID: 25090257 DOI: 10.25011/cim.v37i4.21723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Indexed: 11/03/2022]
Abstract
The 2013 joint Canadian Society of Clinician Investigators (CSCI)-Clinical Investigator Trainee Association of Canada/Association des cliniciens-chercheurs en formation du Canada (CITAC/ACCFC) annual general meeting(AGM) was held in Ottawa, September 2013. The symposium focused on "Applications of the 'omics' to Clinical Practice", with presentations from Drs. William T. Gibson (University of British Columbia), Julie Ho (University of Manitoba) and David Hwang (University of Toronto), discussing topics of genome, proteome and the microbiome, respectively. Other highlights from the 2013 AGM include presentations by Dr. Salim Yusuf (McMaster University, 2013 CSCI-RCPSC Henry Friesen Award winner), Dr. Gary Lewis (University of Toronto, 2013 CSCI Distinguished Scientist Award winner) and Dr. Michael Taylor (University of Toronto, 2013 Joe Doupe Award winner). The CSCI/CITAC/Friends of CIHR Joint Symposium consisted of presentations from Drs. John Bell (University of Ottawa), Dan Drucker (University of Toronto) and Heather J. Dean (University of Manitoba). Finally, the meeting ended with the presentation "The Power of an Idea to Bring Ideas to Power" by Dr. Harvey V. Fineberg (President, U.S. Institute of Medicine), the winner of the 2013 Henry Friesen International Prize. Also presented at the conference was research by clinician investigator (CI) trainees from across Canada; ie., those enrolled in MD/MSc, MD/PhD or Clinician Investigator Program(CIP) programs. Canadian trainees' research extended beyond the pillar of biomedical research, covering the spectrum between basic and clinical research, with a focus on the causes of significant morbidity and mortality for Canadians, including cancers, infectious diseases and other maladies. It is this research that we have summarized in this review.
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Antoun G, Ram VD, Wang X, Wilcox JT, Yoon JY. Scientific overview: CSCI – CITAC Annual General Meeting and Young Investigator’s Forum 2012. CLIN INVEST MED 2013; 36:E248-52. [DOI: 10.25011/cim.v36i5.20124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Indexed: 11/03/2022]
Abstract
In 2012, the Annual General Meeting of the Clinical Investigator Trainee Association of Canada – Association des cliniciens-chercheurs en formation du Canada (CITAC – ACCFC) and the Canadian Society of Clinician Investigators (CSCI) was held 19-21 September in Ottawa. Several globally-renowned scientists, including 2012 Friesen International Prize recipient, Dr. Marc Tessier-Lavigne, the CSCI/Royal College Henry Friesen Award recipient, Dr. Morley Hollenberg, and the recipient of the Joe Doupe Young Investigator Award, Dr. Phillip Awadalla, presented on a range of topics on research in basic and translational science in medicine.
This year’s CITAC Symposium featured presentations by Dr. Alain Beaudet, Dr. Michael Strong and Dr. Vivek Goel on the Role of Physician Scientists in Public Health and Policy, which was followed by a lively discussion on the role of basic science and clinical research in patient-oriented policy development.
This scientific overview highlights the research presented by trainees at both the oral plenary and poster presentation sessions. As at previous meetings, research questions investigated by this year’s trainees span multiple medical disciplines; from basic science to clinical research to medical education. Below is a summary of the presentations showcased at the Young Investigator’s Forum.
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Thrush AB, Antoun G, Boushel R, Doucet É, Imbeault P, McPherson R, Dent R, Harper ME. Investigating The Metabolic Basis for Weight loss Variability in Obese Humans. Can J Diabetes 2013. [DOI: 10.1016/j.jcjd.2013.03.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Yin H, Pasut A, Soleimani VD, Bentzinger CF, Antoun G, Thorn S, Seale P, Fernando P, van Ijcken W, Grosveld F, Dekemp RA, Boushel R, Harper ME, Rudnicki MA. MicroRNA-133 controls brown adipose determination in skeletal muscle satellite cells by targeting Prdm16. Cell Metab 2013; 17:210-24. [PMID: 23395168 PMCID: PMC3641657 DOI: 10.1016/j.cmet.2013.01.004] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 08/18/2012] [Accepted: 01/11/2013] [Indexed: 12/17/2022]
Abstract
Brown adipose tissue (BAT) is an energy-dispensing thermogenic tissue that plays an important role in balancing energy metabolism. Lineage-tracing experiments indicate that brown adipocytes are derived from myogenic progenitors during embryonic development. However, adult skeletal muscle stem cells (satellite cells) have long been considered uniformly determined toward the myogenic lineage. Here, we report that adult satellite cells give rise to brown adipocytes and that microRNA-133 regulates the choice between myogenic and brown adipose determination by targeting the 3'UTR of Prdm16. Antagonism of microRNA-133 during muscle regeneration increases uncoupled respiration, glucose uptake, and thermogenesis in local treated muscle and augments whole-body energy expenditure, improves glucose tolerance, and impedes the development of diet-induced obesity. Finally, we demonstrate that miR-133 levels are downregulated in mice exposed to cold, resulting in de novo generation of satellite cell-derived brown adipocytes. Therefore, microRNA-133 represents an important therapeutic target for the treatment of obesity.
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Affiliation(s)
- Hang Yin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
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Alvarez-Saavedra M, Antoun G, Yanagiya A, Oliva-Hernandez R, Cornejo-Palma D, Perez-Iratxeta C, Sonenberg N, Cheng HYM. miRNA-132 orchestrates chromatin remodeling and translational control of the circadian clock. Hum Mol Genet 2010; 20:731-51. [PMID: 21118894 DOI: 10.1093/hmg/ddq519] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mammalian circadian rhythms are synchronized to the external time by daily resetting of the suprachiasmatic nucleus (SCN) in response to light. As the master circadian pacemaker, the SCN coordinates the timing of diverse cellular oscillators in multiple tissues. Aberrant regulation of clock timing is linked to numerous human conditions, including cancer, cardiovascular disease, obesity, various neurological disorders and the hereditary disorder familial advanced sleep phase syndrome. Additionally, mechanisms that underlie clock resetting factor into the sleep and physiological disturbances experienced by night-shift workers and travelers with jet lag. The Ca(2+)/cAMP response element-binding protein-regulated microRNA, miR-132, is induced by light within the SCN and attenuates its capacity to reset, or entrain, the clock. However, the specific targets that are regulated by miR-132 and underlie its effects on clock entrainment remained elusive until now. Here, we show that genes involved in chromatin remodeling (Mecp2, Ep300, Jarid1a) and translational control (Btg2, Paip2a) are direct targets of miR-132 in the mouse SCN. Coordinated regulation of these targets underlies miR-132-dependent modulation of Period gene expression and clock entrainment: the mPer1 and mPer2 promoters are bound to and transcriptionally activated by MeCP2, whereas PAIP2A and BTG2 suppress the translation of the PERIOD proteins by enhancing mRNA decay. We propose that miR-132 is selectively enriched for chromatin- and translation-associated target genes and is an orchestrator of chromatin remodeling and protein translation within the SCN clock, thereby fine-tuning clock entrainment. These findings will further our understanding of mechanisms governing clock entrainment and its involvement in human diseases.
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Affiliation(s)
- Matías Alvarez-Saavedra
- Ottawa Institute of Systems Biology and Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, Ont., Canada K1H 8M5
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Antoun G, Baylin SB, Ali-Osman F. DNA methyltransferase levels and altered CpG methylation in the total genome and in the GSTP1 gene in human glioma cells transfected with sense and antisense DNA methyltransferase cDNA. J Cell Biochem 2000; 77:372-81. [PMID: 10760946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
This study examines the efficacy of using plasmid expression vectors containing sense and antisense DNA MTase cDNA to both up- and downregulate intracellular DNA MTase levels in human glioma cells. The effects of the changes in MTase levels on global genomic DNA methylation and on the methylation status of CpG dinucleotides in the GSTP1 gene were determined in a glioma cell line that overexpresses the GSTP1 gene. In cells transfected with sense DNA MTase cDNA, MTase gene transcripts increased to a maximum of 2. 5-fold at 24 h, while MTase activity increased to a maximum of 3. 6-fold at 48 h. The effects of antisense MTase cDNA transfections were less pronounced, and levels of MTase gene transcripts and enzyme activity in transfectants were decreased to only, approximately, one-half the levels of controls. The alterations in DNA MTase expression were associated with corresponding changes in the level of global DNA methylation and in the methylation of the GSTP1 gene in the cells, however, with no detectable morphological or cytotoxic effects on the cells. No significant changes in GSTP1 gene expression were detected after the transfections, presumably because of the high levels of basal GSTP1 expression in the cells. Consequently, the p16 gene, known to be repressed transcriptionally by DNA methylation, was examined for the functional effects of the altered MTase levels. The results showed a 2-fold decrease in p16 gene transcripts with the sense MTase transfectants, while in the MTase antisense-transfected cells p16 transcript levels increased by 30%. Together, these results demonstrate the feasibility of using both sense and antisense DNA MTase expression vectors to regulate DNA MTase levels in glioma cells and that, over relatively short periods of time, the alterations in MTase activities are not deleterious to the cells. The system provides a model with which the role of DNA methylation in critical genes and DNA sequences can be investigated in glioma cells.
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Affiliation(s)
- G Antoun
- Department of Neurosurgery, Section of Molecular Therapeutics, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Ali-Osman F, Akande O, Antoun G, Mao JX, Buolamwini J. Molecular cloning, characterization, and expression in Escherichia coli of full-length cDNAs of three human glutathione S-transferase Pi gene variants. Evidence for differential catalytic activity of the encoded proteins. J Biol Chem 1997; 272:10004-12. [PMID: 9092542 DOI: 10.1074/jbc.272.15.10004] [Citation(s) in RCA: 495] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We report the isolation of three full-length cDNAs corresponding to the mRNAs of closely related glutathione S-transferase (GST) Pi genes, designated hGSTP1*A, hGSTP1*B, and hGSTP1*C, expressed in normal cells and malignant gliomas. The variant cDNAs result from A --> G and C --> T transitions at nucleotides +313 and +341, respectively. The transitions changed codon 104 from ATC (Ile) in hGSTP1*A to GTC (Val) in hGSTP1*B and hGSTP1*C and changed codon 113 from GCG (Ala) to GTG (Val) in hGSTP1*C. Both amino changes are in the electrophile-binding active site of the GST Pi peptide. Computer modeling of the deduced crystal structures of the encoded peptides showed significant deviations in the interatomic distances of critical electrophile-binding active site amino acids as a consequence of the amino acid changes. The encoded proteins expressed in Escherichia coli and purified by GSH affinity chromatography showed a 3-fold lower Km (CDNB) and a 3-4-fold higher Kcat/Km for the hGSTP1*A encoded protein than the proteins encoded by hGSTP1*B and hGSTP1*C. Analysis of 75 cases showed the relative frequency of hGSTP1*C to be 4-fold higher in malignant gliomas than in normal tissues. These data provide conclusive molecular evidence of allelopolymorphism of the human GST Pi gene locus, resulting in active, functionally different GST Pi proteins, and should facilitate studies of the role of this gene in xenobiotic metabolism, cancer, and other human diseases.
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Affiliation(s)
- F Ali-Osman
- Section of Molecular Therapeutics, Department of Experimental Pediatrics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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Ali-Osman F, Antoun G, Wang H, Rajagopal S, Gagucas E. Buthionine sulfoximine induction of gamma-L-glutamyl-L-cysteine synthetase gene expression, kinetics of glutathione depletion and resynthesis, and modulation of carmustine-induced DNA-DNA cross-linking and cytotoxicity in human glioma cells. Mol Pharmacol 1996; 49:1012-20. [PMID: 8649339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Glutathione (GSH) depletion by buthioninine sulfoximine (BSO) is being explored clinically as a means of enhancing the efficacy of cancer chemotherapy. We investigated the kinetics of GSH depletion and altered gamma-L-glutamyl-L-cysteine synthetase (gamma-GC-S) gene expression in two human malignant glioma cell lines, HBT5 and HBT28, and examined how these relate to GSH resynthesis and changes in DNA interstrand cross-link induction and cytotoxicity of 1,3-bis(2-chloroethyl)-nitrosourea (BCNU). GSH content was 54 and 126 nmol/mg/protein in HBT 5 and HBT 28, respectively, and after a 24-hr exposure to 100 microM BSO was decreased by 95% in HBT 5 and 91% in HBT 28. Basal gamma-GC-S enzyme activity in HBT 28 was twice that in HBT 5, and steady state gamma-GC-S gene transcripts were 2.6-fold higher in HBT 28 than in HBT 5, with no apparent amplification or rearrangement of the gene in either cell line. BSO exposure (100 microM) for 24 hr increased gamma-GC-S gene transcripts by 1.7-fold in HBT 5 and 2.8-fold in HBT 28. After BSO removal, the rate of GSH resynthesis in HBT 28 was twice that in HBT 5. Continuous BSO exposure increased the level of BCNU-induced DNA interstrand cross-links, and cytotoxicity was significantly higher in cells exposed continuously to BSO than in cells with only a 24-hr BSO preexposure. This increase was, however, greater in HBT 28 than in HBT 5. These findings indicate significant heterogeneity in the effects of BSO on gamma-GC-S gene expression and in the ability of BSO to sensitize tumors and cell lines to BCNU. The data also suggest that by preventing GSH resynthesis, a greater level of cytotoxicity is achieved with continuous BSO exposure than with BSO preexposure alone.
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Affiliation(s)
- F Ali-Osman
- Department of Experimental Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, 77030, USA.
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