Atmospheric oxygen accelerates the induction of a post-mitotic phenotype in human dermal fibroblasts: the key protective role of glutathione.
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.
Alaluf
S
S
Unilever Research, Colworth Laboratory, Sharnbrook, Bedford, United Kingdom. simon.alaluf@unilever.com
Muir-Howie
H
H
Hu
H L
HL
Evans
A
A
Green
M R
MR
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002454:Cell Differentiation; D002478:Cells, Cultured; D002999:Clone Cells; D004247:DNA / Q000032:analysis; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007231:Infant, Newborn; D008297:Male; D008938:Mitosis; D018384:Oxidative Stress / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology*; D010641:Phenotype; D012867:Skin / Q000166:cytology* / Q000187:drug effects; D012879:Skin Physiological Phenomena / Q000187:drug effects*
D000975:Antioxidants; D019328:Buthionine Sulfoximine; D004247:DNA; D006861:Hydrogen Peroxide; D005978:Glutathione; D010100:Oxygen; D000111:Acetylcysteine