BACKGROUND: Type I collagen is a major component of extracellular cellular matrix in tissue. It is synthesized by human skin fibroblasts. However, synthesis of type I collagen is markedly-decreased in senescent fibroblasts. In the cell cycle, the hallmark of senescent fibroblasts is a permanent G1 phase arrest. However it is largely unknown whether the expression of type I collagen protein is decreased by the G1 phase arrest in human skin fibroblasts after UVB irradiation, serum starvation, or mimosine, an inducer of the G1 phase arrest treatment. OBJECTIVE: The purpose of this study was to investigate the expression of type I collagen protein in G1 phase- arrested human skin fibroblasts after UVB irradiation, serum starvation, and mimosine treatment. METHODS: To induce G1 phase arrest in the cell cycle, human skin fibroblasts were irradiated by UVB (100, 200, 300 mJ/cm(2)), subjected to serum starvation for 5 days, or mimosine treatment (50, 100, 200 uM). The expressions of type I collagen protein were analyzed by Western blot analysis. RESULTS: The G1 phase of cell populations were increased by a dose or time-dependent manner with UVB irradiation, serum starvation, and mimosine-treated human skin fibroblasts. The expression of type I collagen protein was markedly-decreased by UVB, serum starvation, and mimosine treatment. CONCLUSION: The expression of type I collagen protein in human skin fibroblasts is decreased by UVB irradiation, serum starvation, and mimosine treatment through induction of G1 phase cell cycle arrest.
Blotting, Western ; Cell Cycle ; Cell Cycle Checkpoints ; Collagen Type I* ; Down-Regulation* ; Fibroblasts* ; G1 Phase ; G1 Phase Cell Cycle Checkpoints* ; Gene Expression* ; Humans* ; Mimosine ; Skin* ; Starvation