title: Matrix metalloproteinases are down-regulated in rat lenses exposed to oxidative stress.
abstract: Matrix metalloproteinases are important biological effectors of tissue remodelling. Increased MMP expression occurs during injury, inflammation, cellular transformation, and oxidative stress. Oxidative stress in the lens, a causal factor in cataractogenesis, has been shown to induce MMP secretion. The objective of this study was to assess the expression of MMPs and their regulators in an oxidative stress model of cataract, where epithelial cell death and cortical fibre cell swelling occurs in rat lenses after exposure to riboflavin, oxygen, and light. Two time points (4 and 7 hr of exposure) were chosen in order to compare transparent lenses with partially opaque lenses. MMP activity, protein, and mRNA levels were measured. The results show that MMP-2, MMP-9, MT1-MMP, and MT3-MMP are down-regulated by oxidative stress and that the down-regulation is most likely due to reduced gene transcription. In contrast, genes for catalase, glutathione peroxidase, and GAPDH are essentially unaffected, while beta-actin mRNA and protein levels are markedly increased at both time points. The down-regulation of MMPs occurs in lenses still seemingly transparent after 4 hr of exposure, indicating that reduced MMP activity is a relatively early response to the oxidative stress. Moreover, in our model system, MMP inhibition, not induction, is associated with cataractogenesis.
authors.affiliation: Section of Molecular Therapeutics, National Eye Institute, National Institutes of Health, Building 7, Room 202, 9000 Rockville Pike, Bethesda, MD 20892, USA.
authors.forename: Molykutty
authors.initials: M
authors.lastname: John
authors.forename: Cynthia
authors.initials: C
authors.lastname: Jaworski
authors.forename: Zhengguang
authors.initials: Z
authors.lastname: Chen
authors.forename: Saradha
authors.initials: S
authors.lastname: Subramanian
authors.forename: Wanchao
authors.initials: W
authors.lastname: Ma
authors.forename: Fang
authors.initials: F
authors.lastname: Sun
authors.forename: Dayu
authors.initials: D
authors.lastname: Li
authors.forename: Abraham
authors.initials: A
authors.lastname: Spector
authors.forename: Deborah
authors.initials: D
authors.lastname: Carper
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002386:Cataract / Q000201:enzymology* / Q000378:metabolism; D015536:Down-Regulation; D007908:Lens, Crystalline / Q000201:enzymology*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D046509:Tissue Culture Techniques; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism
chemical_list: D000199:Actins; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9