Redox Regulation of the G1 to S Phase Transition in the Mouse Embryo Fibroblast Cell Cycle

摘要: The hypothesis that intracellular oxidation/reduction (redox) reactions regulate the G(0)-G(1) to S-phase transition in mouse embryonic fibroblast cell cycle was investigated. Intracellular redox state modulated with a thiol-antioxidant, N-acetyl-L-cysteine (NAC), and progression measured using BrdUrd pulse-chase flow cytometric analysis. Treatment NAC for 12 h resulted an approximately 6-fold increase low-molecular-weight thiols decrease MFI of oxidation-sensitive probe, dihydrofluorescein diacetate, indicating shift toward more reducing environment. NAC-induced alterations caused selective delays from S phase serum-starved cells were serum stimulated reenter as well inhibit G(1) asynchronous cultures no significant phase, G(2)+M transits. treatment also showed 70% cyclin D1 protein levels 3-4-fold p27 levels, which correlated decreased retinoblastoma phosphorylation. Cells released transient fluorescence oxidized glutathione content between 0 8 after release, oxidizing These changes followed by D1, p27, hyperphosphorylation subsequent entry into 8-12 removal NAC. results support within mammalian might provide mechanistic link metabolic processes early activation G(1)-regulatory proteins preparation phase.