Transcriptome Analysis of Skin Photoaging in Chinese Females Reveals the Involvement of Skin Homeostasis and Metabolic Changes

BACKGROUND Photoaging is cumulative damage to skin, caused by chronic, repeated solar radiation exposure. Its molecular mechanisms are poorly understood at the level of global gene expression. OBJECTIVE This study set out to uncover genes and functional modules involved in photoaging at the level of transcription, with the use of skin samples from Chinese women. METHODS Using the Illumina microarray platform, we compared the genome-wide expression profiles of 21 pairs of sun-exposed pre-auricular and sun-protected post-auricular skin samples from northern Chinese women. RESULTS With microarray analysis, 1,621 significantly regulated genes due to photoaging were identified from skin samples. These genes were subjected to functional enrichment analyses with both the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation databases. As revealed by the functional analyses, the up-regulated functional modules in sun-exposed pre-auricular skin were related to various cellular activities in regulation of the skin homeostasis (e.g., the KEGG pathways TGF-beta signaling pathway and ECM-receptor interaction), whereas the down-regulated functional modules were mostly metabolic-related. Additionally, five selected genes (HOXA5, LEPR, CLDN5, LAMC3, and CGA) identified as differentially-expressed were further confirmed by quantitative real-time PCR (Q-RT-PCR). CONCLUSION Our findings suggest that disruption of skin homeostasis and down-regulation of skin metabolism may play important roles in the process of photoaging.