More Than Skin Deep – the Effects of Ultraviolet Radiation on Cathepsin K and Progerin Expression in Cultured Dermal Fibroblasts

INTRODUCTION: Photoaging is a premature skin aging developing secondarily to the excessive exposure to ultraviolet radiation. Due to its complexity, an exact mechanism of photoaging has not been found yet; however, recent research has shown two new emerging players in this process – cathepsin K and progerin. AIM: To evaluate how different wavelengths of ultraviolet radiation (UVA, narrowband UVB and broadband UVB) influence cathepsin K and progerin protein and mRNA expression in dermal cultured fibroblasts. MATERIALS AND METHODS: Primary human dermal fibroblasts (Detroit 551, ATCC CCL-110) were cultured and irradiated with UVA, narrowband UVB (UVBnb) and broadband UVB (UVBwb). Fibroblasts were irradiated with 2 protocols: single high-dose exposure to UVR with protein/mRNA extraction immediately after exposure, 24 h after exposure and 48 h after exposure, and repeated (0 h, 24 h and 48 h) low-dose exposure to UVR with protein/mRNA extraction 48 h after first exposure. RESULTS: Single high doses of UVA, UVBwb and UVBnb resulted in decreased expression of cathepsin K and progerin protein/mRNA in all subsequent time points. Repeated exposure to low doses of UVA results in significant increase of progerin mRNA and significant decrease of progerin protein after 48 h, but repeated exposure to UVBwb and UVBnb resulted in decreased progerin mRNA and protein expression. Repeated exposure to UVA, UVBwb and UVBnb resulted in decreased cathepsin K protein and mRNA expression. CONCLUSION: The results suggest that there could be another progerin/cathepsin K regulatory pathway, which has not been described yet. Being contradictory with previous research, the influence of ultraviolet radiation on progerin and cathepsin K needs to be further elucidated.