title: High glucose-induced oxidative stress promotes autophagy through mitochondrial damage in rat notochordal cells.
abstract: OBJECTIVE
  Diabetes mellitus is associated with an increased risk of intervertebral disc degeneration (IDD). Reactive oxygen species (ROS), oxidative stressors, play a key role in autophagy of diabetes-associated diseases. Mitochondria are known to be the main source of endogenous ROS in most mammalian cell types. The authors therefore conducted the following study to evaluate the effects of high glucose concentrations on the induction of oxidative stress and autophagy through mitochondrial damage in rat notochordal cells.
  
  
  METHODS
  Rat notochordal cells were isolated, cultured, and placed in either 10% fetal bovine serum (normal control) or 10% fetal bovine serum plus two different high glucose concentrations (0.1 M and 0.2 M) (experimental conditions) for one and three days, respectively. We identified and quantified the mitochondrial damage (mitochondrial transmembrane potential) and the generation of ROS and antioxidants (manganese superoxide dismutase [MnSOD] and catalase). We also investigated expressions and activities of autophagy markers (beclin-1, light chain3-I [LC3-I] and LC3-II, autophagy-related gene [Atg] 3, 5, 7, and 12).
  
  
  RESULTS
  An enhanced disruption of mitochondrial transmembrane potential, which indicates mitochondrial damage, was identified in rat notochordal cells treated with both high glucose concentrations. Both high glucose concentrations increased production of ROS by rat notochordal cells in a dose- and time-dependent manner. The two high glucose solutions also enhanced rat notochordal cells' compensatory expressions of MnSOD and catalase in a dose- and time-dependent manner. The proautophagic effects of high glucose concentrations were manifested in the form of enhanced rat notochordal cells' expressions of beclin-1, LC3-II, Atg3, 5, 7, and 12 in a dose- and time-dependent manner. The ratio of LC3-II/LC3-I expression was also increased in a dose- and time-dependent manner.
  
  
  CONCLUSIONS
  The findings from this study demonstrate that high glucose-induced oxidative stress promotes autophagy through mitochondrial damage of rat notochordal cells in a dose- and time-dependent manner. These results suggest that preventing the generation of oxidative stress might be a novel therapeutic target by which to prevent or to delay IDD in patients with diabetes mellitus.
authors.affiliation: Orthopaedic Surgery, Uijongbu St. Mary's Hospital, The Catholic University of Korea School of Medicine, Uijongbu, Korea.
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Park
authors.forename: Jong-Beom
authors.initials: JB
authors.lastname: Park
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy / Q000502:physiology*; D000071186:Beclin-1; D002374:Catalase / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000494:pharmacology*; D063306:Mitophagy / Q000502:physiology*; D023421:Models, Animal; D009672:Notochord / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors
chemical_list: D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C512829:Becn1 protein, rat; D017382:Reactive Oxygen Species; D002374:Catalase; D013482:Superoxide Dismutase; D005947:Glucose
references.citation: Apoptosis. 2010 May;15(5):631-8
references.pmid: 20091349
references.citation: Diabetes. 1991 Apr;40(4):405-12
references.pmid: 2010041
references.citation: Diabetes. 2012 Jan;61(1):23-9
references.pmid: 22187371
references.citation: Diabetes. 2013 Apr;62(4):1270-81
references.pmid: 23223177
references.citation: Arthritis Rheum. 2010 Mar;62(3):791-801
references.pmid: 20187128
references.citation: Autophagy. 2011 Jan;7(1):12-6
references.pmid: 20935505
references.citation: Int J Biochem Cell Biol. 2011 Sep;43(9):1263-6
references.pmid: 21640844
references.citation: Free Radic Biol Med. 2012 Oct 1;53(7):1399-410
references.pmid: 22820461
references.citation: J Neurosurg Spine. 2009 Dec;11(6):741-8
references.pmid: 19951028
references.citation: Curr Hypertens Rep. 2012 Dec;14(6):540-7
references.pmid: 23001875
references.citation: Cell Cycle. 2009 Feb 1;8(3):391-3
references.pmid: 19177014
references.citation: Annu Rev Pathol. 2013 Jan 24;8:105-37
references.pmid: 23072311
references.citation: Cell Prolif. 2012 Dec;45(6):487-98
references.pmid: 23030059
references.citation: Int Orthop. 2013 Jun;37(6):1179-86
references.pmid: 23503638
references.citation: Ann N Y Acad Sci. 2010 Jul;1201:79-83
references.pmid: 20649543
references.citation: Exp Mol Med. 2012 Feb 29;44(2):69-72
references.pmid: 22257881
references.citation: Nat Cell Biol. 2007 Oct;9(10):1102-9
references.pmid: 17909521
references.citation: Antioxid Redox Signal. 2007 Mar;9(3):343-53
references.pmid: 17184177
references.citation: Cell Cycle. 2010 Sep 1;9(17):3442-8
references.pmid: 20814234
references.citation: FEBS Lett. 2010 Apr 2;584(7):1296-301
references.pmid: 20188731
references.citation: Curr Pharm Des. 2011 Dec 1;17(36):3947-58
references.pmid: 22188447
references.citation: Autophagy. 2005 Apr;1(1):46-52
references.pmid: 16874027
references.citation: Spine (Phila Pa 1976). 2005 Jun 1;30(11):1247-51
references.pmid: 15928547
references.citation: J Bone Joint Surg Am. 2005 Jun;87(6):1338-42
references.pmid: 15930545
references.citation: Spine (Phila Pa 1976). 2003 May 15;28(10):982-90
references.pmid: 12768135
references.citation: Spine (Phila Pa 1976). 2001 Jan 15;26(2):142-6
references.pmid: 11154532