title: Using an in vitro model to study oxidised protein accumulation in ageing fibroblasts.
abstract: BACKGROUND
  The accumulation of oxidised proteins in ageing cells and tissues results from an increase in oxidant damage coupled with impaired degradation of the damaged proteins. Heat Shock Proteins (HSP) and other chaperones are required to recognise damaged proteins and transport them to the lysosomal and proteasomal degradation pathways. How these systems fail in ageing cells is not clear.
  
  
  METHODS
  We monitor oxidised protein accumulation, the activity of the proteasome and lysosomal proteases, and HSP levels in MRC-5 fibroblasts throughout their mitotic lifespan. We then use a novel in vitro cell culture model to experimentally generate oxidised proteins in young and old MRC-5 fibroblasts and compare their rates of degradation and changes in the key pathways involved in oxidised protein removal.
  
  
  RESULTS
  We show that the activity of the proteasome and some lysosomal enzymes decreases with ageing in MRC-5 cells as do levels of HSP70 but this is not associated with an accumulation of oxidised proteins which only occurs as cells closely approach post-mitotic senescence. Old cells are unable to degrade experimentally generated oxidised proteins as efficiently as young cells. Exposure to mild heat stress however increases the efficiency of oxidised protein degradation by young cells and increases levels of HSP70.
  
  
  CONCLUSIONS
  Our results highlight the importance of the HSP/chaperone system in oxidised protein metabolism, particularly in ageing cells.
  
  
  CONCLUSIONS
  These data might have implications for the development of therapies for pathologies associated with protein accumulation and suggest that the HSP/chaperone system would be an important target.
authors.affiliation: The Cell Biology Group, School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
authors.forename: Nae
authors.initials: N
authors.lastname: Shiozawa-West
authors.affiliation: The Cell Biology Group, School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
authors.forename: Rachael A
authors.initials: RA
authors.lastname: Dunlop
authors.affiliation: The Cell Biology Group, School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia. Electronic address: Kenneth.rodgers@uts.edu.au.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Rodgers
mesh_terms: D002478:Cells, Cultured; D016922:Cellular Senescence; D004295:Dihydroxyphenylalanine / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000502:physiology; D006801:Humans; D010084:Oxidation-Reduction; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D011506:Proteins / Q000378:metabolism*
chemical_list: D018840:HSP70 Heat-Shock Proteins; D011506:Proteins; D004295:Dihydroxyphenylalanine; D046988:Proteasome Endopeptidase Complex
keywords: Ageing; DOPA; Lysosomes; Oxidised proteins; Proteasome