The comparison of microRNA profile of the dermis between the young and elderly.

Background: Skin aging is a process of structural and compositional remodeling that can be manifested as wrinkling and sagging. Remarkably, the dermis plays a dominant role in the process of skin aging. Recent studies suggest that microRNAs (miRNAs) may play a role in the regulation of gene expression in organism aging. However, studies about age-related miRNAs in human skin remain limited.

Objective: To obtain an overall view of miRNAs expression in human aged dermis by comparison of dermis samples between young and elderly, construct the miRNA-gene-network and reveal the pivotal miRNAs in the regulatory network.

Methods: Human dermis tissue was obtained from 12 donors, including 6 of young group and 6 of elderly one. The miRNA microarray and data analysis were performed. Target genes of differentially expressed miRNAs were predicted, followed by a gene ontology and pathway enrichment analysis. A miRNA-gene-network was then constructed, and the pivotal miRNAs in the network was revealed. Primary human dermal fibroblasts (HDFs) were isolated, and the cellular senescence was induced by serial passaging. Alteration in the expression of miRNAs between young and senescent fibroblasts was evaluated by real-time quantitative RT-PCR. MiR-34b-5p mimics were transfected into primary HDFs. Subsequent cell cycle analysis was performed and expression level of COL1A1, elastin and MMP-1 were evaluated.

Results: The expression of a total of 40 miRNAs (25 upregulated and 15 downregulated) was found to be significantly altered in aged dermis compared with young dermis. Real-time quantitative PCR results confirmed the differential expression of miR-34 family and miR-29 family between young and aged dermis. A computational approach demonstrated that predicted target genes of the miRNA profile were found to be mainly involved in processes including cell adhesion, collagen synthesis, positive or negative regulation of transcription, as well as pathways such as insulin signaling pathway, ErbB (Erythroblastic Leukemia Viral Oncogene Homolog) signaling pathway and Focal adhesion pathway. The miRNA-Gene-Network revealed that miR-34 family, miR-29 family and miR-424 may play a dominant role in the regulatory network. A similar miRNA alteration was observed in senescent fibroblasts in vitro, and the age-related miRNA profile may interact with p16 pathway to regulate the fibroblasts' senescence. Additionally, transfection of miR-34b-5p mimics induced cell cycle arrest in HDFs, decreased the expression of both COL1A1 and elastin and increased MMP-1 expression.

Conclusion: The miR-34 family and miR-29 family expressed differentially in young and aged dermis. MiR-34 in HDFs modulated the cell function and expression of MMP-1, COL1A1 and elastin. The miRNAs may play critical roles in affecting dermis aging.