Human skin has extensive characteristics in morphology and physiology compared to other primates. Skin is directly exposed to the external environment and plays essential roles, including maintenance of body temperature and moisture. The aim of our study is to understand how human-specific characteristics of skin had been acquired during the evolutionary process at genetic level. We comprehensively compared the expression levels of genes in skin between humans and apes to identify genes with human-specific expression patterns, which may contribute to human-specific characteristics.
We conducted mRNA expression analysis by using the next-generation sequencing (RNA-Seq) of skin samples of humans (n=3), chimpanzees (n=3), gorillas (n=3), and orangutans (n=3). We extracted genes showing significantly different expression patterns for each species compared to the other primates. The expression levels of 23 and 21 genes were significantly higher and lower in humans compared to apes, respectively. The number of genes with significantly different expression levels was higher in the human lineage (44 genes in total) relative to chimpanzee (22 genes in total) and gorilla (14 genes in total). We conducted gene ontology analysis for 44 genes with human-specific expression patterns to know what functions these genes would be related to. This analysis revealed that several genes have roles in developmental and metabolic process.
The larger number of genes with human-specific expression patterns may contribute to acquirement of human-specific characteristics in skin.