Abstract
This study was conducted to elucidate effects of silk protein, sericin, on human skin fibroblast cell line CCD-1093Sk with special reference to the changes of gene expression after UVB exposure.
Cultured cells (70% confluency) were irradiated by UVB. To evaluate the effect of sericin, the cells were exposed to UVB through films composed of sericin. Expression level of the genes of interest was quantitated by real-time RT-PCR.
Apoptosis-related genes. Gene expression of Bax, Bcl-2 and Bcl-XL was dose-dependently up-regulated, at 4 hours and 6 hours after UVB irradiation (1-100 mJ/cm2), whereas the irradiation through sericin films significantly inhibited up-regulation of these genes.
Collagen synthesis / degradation-related genes. We examined the mRNA expression levels of collagen synthesis / degradation-related genes at 24 hours after the UVB irradiation. UVB-induced up-regulation of matrix metalloproteinase mRNAs (MMP1 and MMP3) was suppressed in the cells that were irradiated through sericin films. After UVB irradiation (5-50 mJ/cm2), mRNA expression of CTGF that stimulates type I procollagen production was down-regulated to 50% level as compared with that of the non-irradiated cells. On the contrary, when the cells were exposed to UVB through sericin films, CTGF mRNA increased by 1.8 -fold in comparison with that of non-irradiated cells.
Conclusion. Gene expression patterns after UVB exposure in the cell line that we used were modified when the cells were exposed through sericin films.
