Single-cell Transcriptome Identification of UV- and Visible-light-induced Genes in Human Melanocytes in Vivo

Medical condition and pathology studied skin pigmentation. Justification / rationale for the study UV are both the physiological stimulus for skin pigmentation and the main etiological factor in melanoma. Recently, visible (blue) light has also been described to induce skin pigmentation, without any obvious pro-carcinogenic effect. Studies have been carried out to identify genes induced by UV in melanocytes and to understand the mechanisms responsible for photo-induced skin pigmentation. However, the rarity of these cells in the epidermis (3% of cells) has so far been an insurmountable obstacle to achieving this goal. The same is true for visible light, for which the data is even more patchy. The advent of transcriptome analysis techniques at the single cell or single nucleus level will allow us to overcome this obstacle and identify the transcriptional effects of UV and blue light in melanocytes in-situ, as well as in other skin cells (keratinocytes, fibroblasts). Understanding the molecular mechanisms regulated by UV and blue light in melanocytes and other cells will reveal new key steps in skin pigmentation. The data from our study will be used to develop new photoprotective agents as well as new treatments for pigmentary pathologies. Primary objective Describe the variations in gene expression induced by solar ultraviolet (UV) radiation or blue light in human melanocytes in vivo. Secondary objectives Describe the variations in gene expression induced by ultraviolet (UV) radiation sunlight or blue light in other skin cells. Evaluation criteria Single cell transcriptome analysis Immunolabelling on skin sections Population and number of inclusions Healthy male volunteers, phototype III on the Fitzpatrick scale, age 25 + 5 years and of similar corpulence (body mass index between 20 and 28). 2 inclusions Duration of the study Total duration of the study: 12 months Duration of the inclusion phase: 1 month Duration of participation for a patient: 11 days Methodology Tw