ABSTRACT
One of the greatest advances in photodermatology is in the understanding of the molecular events that follow ultraviolet (UV) irradiation of skin. UV exposure changes the cytokine profile within the epidermis. Proteins that have been proposed as chromophores for many of the effects of UV radiation (UVR) are cell surface receptors. UVR causes these receptors to cluster even without binding ligands. Deoxyribonucleic acid (DNA) absorbs all wavelengths of UVR, but pure DNA has a peak of absorption at about 260 nm, and the action spectrum for DNA damage shows a logarithmic decline in absorption as the wavelengths grow longer. DNA is repaired by a complex of proteins and enzymes that organize together at the site of damage. DNA microarrays have allowed a large-scale analysis of transcriptional response of skin cells to UV. Different factors may influence the transcriptional targets of UV, including wavelength, dose, cell type, and the time of expression after irradiation.
