Local Adaptation of Sun-Exposure-Dependent Gene Expression Regulation in Human Skin

Sun-exposure is a key environmental variable in the study of human evolution. several skin-pigmentation genes serve as classical examples of positive selection,suggesting that sun-exposure has significantly shaped worldwide genomic variation. here we investigate the interaction between genetic variation and sun-exposure,and how this impacts gene expression regulation. using rna-seq data from 607 human skin samples,we identified thousands of transcripts that are differentially expressed between sun-exposed skin and non-sun-exposed skin. we then tested whether genetic variants may influence each individual’s gene expression response to sun-exposure. our analysis revealed 10 sun-exposure-dependent gene expression quantitative trait loci (se-eqtls),including genes involved in skin pigmentation (slc45a2) and epidermal differentiation (rassf9). the allele frequencies of the rassf9 se-eqtl across diverse populations correlate with the magnitude of solar radiation experienced by these populations,suggesting local adaptation to varying levels of sunlight. these results provide the first examples of sun-exposure-dependent regulatory variation and suggest that this variation has contributed to recent human adaptation. © 2016 kita,fraser.