title: Glutathione regulates telomerase activity in 3T3 fibroblasts.
abstract: Changes in telomerase activity have been associated either with cancer, when activity is increased, or with cell cycle arrest when it is decreased. We report that glutathione, a physiological antioxidant present at high intracellular concentrations, regulates telomerase activity in cells in culture. Telomerase activity increases in 3T3 fibroblasts before exponential cell growth. The peak of telomerase activity takes place 24 h after plating and coincides with the maximum levels of glutathione in the cells. When cells are treated with buthionine sulfoximine, which decreases glutathione levels in cells, telomerase activity decreases by 60%, and cell growth is delayed. Glutathione depletion inhibits expression of E2F4 and Id2, which regulate the cell cycle. When glutathione levels are restored after incubation with glutathione monoethylester, telomerase activity and the cell cycle-related proteins return to control values. To discover the effect of glutathione redox status on the telomerase multicomplex structure, we incubated protein extracts from fibroblasts with different glutathione redox buffers. Telomerase activity is maximal under reduced conditions i.e. when the reduced/oxidized glutathione ratio is high. Consequently glutathione concentration parallels telomerase activity. These results underscore the main role of glutathione in the control of telomerase activity and of the cell cycle.
authors.affiliation: Department of Physiology, School of Medicine, University of Valencia, Avda. Blasco Ibáñez 17, 46010 Valencia, Spain.
authors.forename: Consuelo
authors.initials: C
authors.lastname: Borrás
authors.forename: Juan M
authors.initials: JM
authors.lastname: Esteve
authors.forename: Juan R
authors.initials: JR
authors.lastname: Viña
authors.forename: Juan
authors.initials: J
authors.lastname: Sastre
authors.forename: José
authors.initials: J
authors.lastname: Viña
authors.forename: Federico V
authors.initials: FV
authors.lastname: Pallardó
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002453:Cell Cycle; D002455:Cell Division; D004396:Coloring Agents / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D050704:E2F4 Transcription Factor; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic; D005978:Glutathione / Q000378:metabolism*; D015151:Immunoblotting; D051797:Inhibitor of Differentiation Protein 2; D051379:Mice; D010084:Oxidation-Reduction; D012097:Repressor Proteins; D019098:Telomerase / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014343:Trypan Blue / Q000494:pharmacology
chemical_list: D004396:Coloring Agents; D004268:DNA-Binding Proteins; D050704:E2F4 Transcription Factor; C497452:Idb2 protein, mouse; D051797:Inhibitor of Differentiation Protein 2; D012097:Repressor Proteins; D014157:Transcription Factors; D019328:Buthionine Sulfoximine; D019098:Telomerase; D005978:Glutathione; D014343:Trypan Blue