Atmospheric oxygen accelerates the induction of a post-mitotic phenotype in human dermal fibroblasts: the key protective role of glutathione

• DOI: 10.1046/j.1432-0436.2000.660209.x
• Publication Date: 2003-03-11T14:32:10Z
• Authors: Simon Alaluf; Helen Muir-Howie; Heng-Long Hu; Anita Evans; Martin R. Green
• Keywords: Male; 0303 health sciences; Infant, Newborn; Mitosis; Cell Differentiation; DNA; Hydrogen Peroxide; Fibroblasts; Glutathione; Antioxidants; Acetylcysteine; Clone Cells; Oxygen; Oxidative Stress; 03 medical and health sciences; Phenotype; Skin Physiological Phenomena; Humans; Buthionine Sulfoximine; Cells, Cultured; Skin

It has been proposed that ageing of human dermal fibroblasts occurs as a multi-stage process during which cells progress from a mitotic to a post-mitotic state. We describe the development of a simple and novel cell-cloning model for identifying and quantifying the different fibroblast morphotypes associated with the induction of post mitotic behaviour. We have found that under atmospheric (20%) oxygen tension a significant proportion of human dermal fibroblasts are rapidly induced to switch from a mitotic to a post-mitotic phenotype. In contrast, under more physiological (4%) oxygen conditions, the induction of a post-mitotic phenotype is largely prevented. Increasing oxidative stress by addition of hydrogen peroxide or depletion of glutathione also induced a switch from a mitotic to a post-mitotic phenotype in these cells, whereas addition of the anti-oxidant N-acetylcysteine under atmospheric (20%) oxygen tension potently inhibited this process. In addition, a statistically significant correlation was observed between the magnitude of intracellular glutathione depletion and the reduction in the population of mitotic cells in this model. We propose that the switch from a mitotic to a post-mitotic phenotype represents a process of cellular ageing and that standard atmospheric oxygen tension imposes a substantial oxidative stress on dermal fibroblasts which accelerates this process in culture. The data also suggest that intracellular glutathione levels strongly influence the induction of a post-mitotic phenotype and that, by implication, depletion of glutathione may play a significant role in the progression of cellular ageing in human skin.