Induction of mRNA for matrix metalloproteinase 1 and tissue inhibitor of metalloproteinases 1 in human skin in vivo by solar simulated radiation

Abstract

Repeated exposure to solar ultraviolet radiation results in premature skin aging due, in part, to the degradation of dermal collagen by fibroblast collagenase (matrix metalloproteinase 1 [MMP-1]). We have established TaqMan(TM) reverse transcription (RT) polymerase chain reaction (PCR) systems to quantify the messenger RNA (mRNA) expression of MMP-1 and its specific inhibitor TIMP-1 in human buttock skin exposed in vivo to solar simulated radiation (SSR). A time-course study (n = 6) with two minimal erythema doses (MED) of SSR showed maximal induction of MMP-1 and TIMP-1 at 24 h. A dose-response study (n = 6) sampled at 24 h revealed that doses of about 1 MED were necessary to induce expression of MMP-1 mRNA, and our data suggest that the response is saturated at about 2 MED. We also investigated SSR-induced gene expression in the dermis and epidermis separately (n = 5). MMP-1 was present in both tissues, but TIMP-1 was only detected in the dermis, In general, we could only measure MMP-1 mRNA in the nonirradiated control skin of volunteers who were smokers. We hypothesize very large interpersonal variation with MMP-1 induction compared with TIMP-1 which was detected in all the control sites. This suggests a lack of relationship between MMP-1 and TIMP-1 mRNA expression. The large donor variability for MMP-1 in all the studies demonstrates that it is important to analyze gene expression individually