title: Mitochondrial vulnerability and increased susceptibility to nutrient-induced cytotoxicity in fibroblasts from leigh syndrome French canadian patients.
abstract: Mutations in LRPPRC are responsible for the French Canadian variant of Leigh Syndrome (LSFC), a severe disorder characterized biochemically by a tissue-specific deficiency of cytochrome c oxidase (COX) and clinically by the occurrence of severe and deadly acidotic crises. Factors that precipitate these crises remain unclear. To better understand the physiopathology and identify potential treatments, we performed a comprehensive analysis of mitochondrial function in LSFC and control fibroblasts. Furthermore, we have used this cell-based model to screen for conditions that promote premature cell death in LSFC cells and test the protective effect of ten interventions targeting well-defined aspects of mitochondrial function. We show that, despite maintaining normal ATP levels, LSFC fibroblasts present several mitochondrial functional abnormalities under normal baseline conditions, which likely impair their capacity to respond to stress. This includes mitochondrial network fragmentation, impaired oxidative phosphorylation capacity, lower membrane potential, increased sensitivity to Ca2+-induced permeability transition, but no changes in reactive oxygen species production. We also show that LSFC fibroblasts display enhanced susceptibility to cell death when exposed to palmitate, an effect that is potentiated by high lactate, while high glucose or acidosis alone or in combination were neutral. Furthermore, we demonstrate that compounds that are known to promote flux through the electron transport chain independent of phosphorylation (methylene blue, dinitrophenol), or modulate fatty acid (L-carnitine) or Krebs cycle metabolism (propionate) are protective, while antioxidants (idebenone, N-acetyl cysteine, resveratrol) exacerbate palmitate plus lactate-induced cell death. Collectively, beyond highlighting multiple alterations in mitochondrial function and increased susceptibility to nutrient-induced cytotoxicity in LSFC fibroblasts, these results raise questions about the nature of the diets, particularly excess fat intake, as well as on the use of antioxidants in patients with LSFC and, possibly, other COX defects.
authors.affiliation: Faculty of Pharmacy, Université de Montréal, Montréal, Canada.
authors.forename: Yan
authors.initials: Y
authors.lastname: Burelle
authors.affiliation: Faculty of Pharmacy, Université de Montréal, Montréal, Canada.
authors.forename: Chantal
authors.initials: C
authors.lastname: Bemeur
authors.affiliation: Montreal Heart Institute, Montreal, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: Rivard
authors.affiliation: Montreal Heart Institute, Montreal, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Thompson Legault
authors.affiliation: Montreal Heart Institute, Montreal, Canada.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Boucher
authors.affiliation: Department of Pediatrics and Clinical Research Unit, Complexe hospitalier de la Sagamie, Chicoutimi, QC, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Morin
authors.affiliation: Montreal Heart Institute, Montreal, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada; Department of Medicine, Faculty of Medicine, Université de Montréal, Montréal, Canada.
authors.forename: Lise
authors.initials: L
authors.lastname: Coderre
authors.affiliation: Montreal Heart Institute, Montreal, Canada; Department of Nutrition, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Des Rosiers
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D002118:Calcium / Q000378:metabolism; D002170:Canada; D016022:Case-Control Studies; D002463:Cell Membrane Permeability; D002648:Child; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007888:Leigh Disease / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics; D010085:Oxidative Phosphorylation; D010641:Phenotype; D017382:Reactive Oxygen Species; D013312:Stress, Physiological; D013481:Superoxides / Q000378:metabolism; D055815:Young Adult
chemical_list: C087940:LRPPRC protein, human; D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D000255:Adenosine Triphosphate; D002118:Calcium
references.citation: Am J Hum Genet. 1993 Aug;53(2):481-7
references.pmid: 8392290
references.citation: PLoS One. 2011;6(12):e28823
references.pmid: 22174907
references.citation: Proc Natl Acad Sci U S A. 2003 Jan 21;100(2):605-10
references.pmid: 12529507
references.citation: Biochem J. 2004 Aug 15;382(Pt 1):331-6
references.pmid: 15139850
references.citation: Exp Gerontol. 2010 Aug;45(7-8):466-72
references.pmid: 20064600
references.citation: Biofactors. 2012 Mar-Apr;38(2):158-66
references.pmid: 22419586
references.citation: Biochim Biophys Acta. 2003 Sep 1;1639(1):53-63
references.pmid: 12943968
references.citation: J Med Genet. 2011 Mar;48(3):183-9
references.pmid: 21266382
references.citation: Brain. 2009 Apr;132(Pt 4):833-42
references.pmid: 19336460
references.citation: Am J Physiol. 1995 Jan;268(1 Pt 2):H441-7
references.pmid: 7840294
references.citation: Epilepsia. 2007 Jan;48(1):82-8
references.pmid: 17241212
references.citation: Biochim Biophys Acta. 2006 Sep-Oct;1757(9-10):1330-7
references.pmid: 16697347
references.citation: Toxicol Mech Methods. 2013 Jun;23(5):297-302
references.pmid: 23256455
references.citation: Life Sci. 2009 Mar 13;84(11-12):328-36
references.pmid: 19159629
references.citation: EMBO J. 2008 Jan 23;27(2):433-46
references.pmid: 18200046
references.citation: Cytometry A. 2004 Oct;61(2):162-9
references.pmid: 15382028
references.citation: Am J Pathol. 2010 Jul;177(1):447-55
references.pmid: 20522647
references.citation: Hum Mol Genet. 1999 Dec;8(13):2541-9
references.pmid: 10556303
references.citation: Biochim Biophys Acta. 2007 Mar;1772(3):373-81
references.pmid: 17289351
references.citation: Arch Biochem Biophys. 2003 Apr 15;412(2):196-206
references.pmid: 12667483
references.citation: Biochem J. 2013 Sep 15;454(3):447-57
references.pmid: 23822101
references.citation: FEBS Lett. 2000 Jul 28;478(1-2):19-25
references.pmid: 10922462
references.citation: J Pharmacol Exp Ther. 2012 Sep;342(3):608-18
references.pmid: 22700427
references.citation: Int J Biochem Cell Biol. 2009 Oct;41(10):1773-82
references.pmid: 19703648
references.citation: Mitochondrion. 2011 Nov;11(6):954-63
references.pmid: 21945727
references.citation: Biochem J. 1999 Jul 15;341 ( Pt 2):233-49
references.pmid: 10393078
references.citation: Nat Rev Neurol. 2013 Aug;9(8):474-81
references.pmid: 23817350
references.citation: Ann Surg. 2007 Feb;245(2):214-21
references.pmid: 17245174
references.citation: Aging Cell. 2004 Feb;3(1):35-40
references.pmid: 14965354
references.citation: Hum Mol Genet. 2015 Jan 15;24(2):480-91
references.pmid: 25214534
references.citation: Pediatrics. 2007 Mar;119(3):535-43
references.pmid: 17332207
references.citation: Diabetes. 2002 May;51(5):1437-42
references.pmid: 11978640
references.citation: J Mol Cell Cardiol. 2010 Feb;48(2):310-21
references.pmid: 19769982
references.citation: Biochim Biophys Acta. 2010 May;1802(5):443-53
references.pmid: 20153825
references.citation: J Biol Chem. 2011 Dec 2;286(48):41253-64
references.pmid: 21971050
references.citation: J Bioenerg Biomembr. 1999 Oct;31(5):447-55
references.pmid: 10653473
references.citation: J Inherit Metab Dis. 2006 Apr-Jun;29(2-3):327-31
references.pmid: 16763895
references.citation: J Biol Chem. 2005 Apr 1;280(13):12944-55
references.pmid: 15668244
references.citation: Am J Physiol Regul Integr Comp Physiol. 2013 Mar 15;304(6):R393-406
references.pmid: 23364527
references.citation: Curr Treat Options Neurol. 2009 Nov;11(6):414-30
references.pmid: 19891905
references.citation: Circ Res. 2012 Oct 12;111(9):1198-207
references.pmid: 23065343
references.citation: Hum Mol Genet. 2012 Dec 1;21(23):5066-77
references.pmid: 22914734
references.citation: Neuromuscul Disord. 2007 May;17(5):368-75
references.pmid: 17383182
references.citation: Prostaglandins Leukot Essent Fatty Acids. 2008 Feb;78(2):147-55
references.pmid: 18191557
references.citation: Cell Signal. 2011 Oct;23(10):1528-33
references.pmid: 21616143
references.citation: Biochim Biophys Acta. 1995 Jul 17;1241(2):139-76
references.pmid: 7640294
references.citation: FASEB J. 2008 Mar;22(3):703-12
references.pmid: 17928358
references.citation: Mol Biol Cell. 2010 Apr 15;21(8):1315-23
references.pmid: 20200222
references.citation: J Biol Chem. 2008 Oct 24;283(43):29572-85
references.pmid: 18723505
references.citation: Biochim Biophys Acta. 2000 May 6;1485(1):45-55
references.pmid: 10802248
references.citation: Am J Hum Genet. 1993 Aug;53(2):488-96
references.pmid: 8392291
references.citation: Am J Physiol Heart Circ Physiol. 2011 Jan;300(1):H144-53
references.pmid: 20971771
references.citation: FEBS J. 2006 May;273(10):2077-99
references.pmid: 16649987
references.citation: Muscle Nerve. 2006 Sep;34(3):265-83
references.pmid: 16810684
references.citation: J Mol Cell Cardiol. 2006 Dec;41(6):998-1009
references.pmid: 17064727
references.citation: Science. 2004 Jul 30;305(5684):626-9
references.pmid: 15286356
references.citation: Cardiovasc Res. 2000 Jul;47(1):68-73
references.pmid: 10869531
references.citation: J Mol Med (Berl). 2009 May;87(5):515-22
references.pmid: 19255735
references.citation: J Inherit Metab Dis. 2011 Apr;34(2):293-307
references.pmid: 20107904
references.citation: FASEB J. 2003 Oct;17(13):1972-4
references.pmid: 12923074
references.citation: J Clin Invest. 2009 Mar;119(3):573-81
references.pmid: 19188683
references.citation: Biochim Biophys Acta. 2009 Nov;1787(11):1416-24
references.pmid: 19298790
references.citation: Circulation. 2009 Mar 31;119(12):1643-52
references.pmid: 19289642
references.citation: Ann N Y Acad Sci. 2004 Nov;1033:79-91
references.pmid: 15591005
references.citation: Mitochondrion. 2013 Sep;13(5):436-43
references.pmid: 23234723
references.citation: Cytometry A. 2006 Jan;69(1):1-12
references.pmid: 16342116
references.citation: Am J Physiol Cell Physiol. 2005 Oct;289(4):C881-90
references.pmid: 15901599
references.citation: Trends Mol Med. 2003 May;9(5):196-205
references.pmid: 12763524