title: Fibroblasts derived from Gpx1 knockout mice display senescent-like features and are susceptible to H2O2-mediated cell death.
abstract: The Free Radical Theory of Aging proposes that reactive oxygen species (ROS) contribute to the pathophysiology of aging. Our previous data highlight the importance of antioxidant enzymes, superoxide dismutase 1 (Sod1) and glutathione peroxidase 1 (Gpx1), in regulating this process. Previously, we demonstrated that a perturbation in the Sod1-to-Gpx1 ratio, as a consequence of Sod1 overexpression, leads to senescence-like changes. We proposed that this was mediated via the Sod1 dismutation product H2O2, because H2O2 induced similar changes in control cells. However, it has been suggested that H2O2 production, via Sod1 dismutation, is rate-limited by the availability of the substrate O2*-, and therefore age-related changes may occur as a result of other functions of Sod1. In this study, we test this notion in fibroblasts derived from Gpx1 null mutant mice (Gpx1-/-) that have elevated H2O2 as a consequence of the lack of its removal by Gpx1. We demonstrate senescence-like changes in Gpx1-/- fibroblasts that include (1) reduced proliferative capacity, DNA synthesis, and responsiveness to EGF and serum; (2) elevated levels of Cip1; (3) increased NF-kappaB activation; and (4) morphological features of senescent cells. Gpx1-/- fibroblasts also demonstrate a dose-dependent susceptibility to H2O2-induced apoptosis. Our findings suggest that Gpx1 is protective against both ROS-mediated senescence-like changes and oxidant-mediated cell death.
authors.affiliation: Centre for Functional Genomics and Human Disease, Monash University, Monash Medical Centre, Clayton, Victoria, Australia. judy.dehaan@baker.edu.au
authors.forename: Judy B
authors.initials: JB
authors.lastname: de Haan
authors.forename: Cecile
authors.initials: C
authors.lastname: Bladier
authors.forename: Mehrnoush
authors.initials: M
authors.lastname: Lotfi-Miri
authors.forename: Juliet
authors.initials: J
authors.lastname: Taylor
authors.forename: Paul
authors.initials: P
authors.lastname: Hutchinson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Crack
authors.forename: Paul
authors.initials: P
authors.lastname: Hertzog
authors.forename: Ismail
authors.initials: I
authors.lastname: Kola
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D004247:DNA / Q000096:biosynthesis / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005347:Fibroblasts; D017353:Gene Deletion; D005979:Glutathione Peroxidase / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D012333:RNA, Messenger; D004247:DNA; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D000094765:Glutathione Peroxidase GPX1; C000722068:Gpx1 protein, mouse