Possible Role of Single Stranded DNA Binding Protein 3 on Skin Hydration by Regulating Epidermal Differentiation

Background: Skin hydration is a common problem both in elderly and young people as dry skin may cause irritation, dermatological disorders, and wrinkles. While both genetic and environmental factors seem to influence skin hydration, thorough genetic studies on skin hydration have not yet been conducted. Objective: We used a genome-wide association study (GWAS) to explore the genetic elements underlying skin hydration by regulating epidermal differentiation and skin barrier function. Methods: A GWAS was conducted to investigate the genetic factors influencing skin hydration in 100 Korean females along with molecular studies of genes in human epidermal keratinocytes for functional study in vitro. Results: Among several single nucleotide polymorphisms identified in GWAS, we focused on Single Stranded DNA Binding Protein 3 (SSBP3) which is associated with DNA replication and DNA damage repair. To better understand the role of SSBP3 in skin cells, we introduced a calcium-induced differentiation keratinocyte culture system model and found that SSBP3 was upregulated in keratinocytes in a differentiation dependent manner. When SSBP3 was overexpressed using a recombinant adenovirus, the expression of differentiation-related genes such as loricrin and involucrin was markedly increased. Conclusion: Taken together, our results suggest that genetic variants in the intronic region of SSBP3 could be determinants in skin hydration of Korean females. SSBP3 represents a new candidate gene to evaluate the molecular basis of the hydration ability in individuals. (Ann Dermatol 30(4) 432∼440, 2018)