Aquaporin-3 gene and protein expression in sun-protected human skin decreases with skin ageing

Aquaporin 3 (AQP3) is a protein implicated in skin hydration. AQP3 null mice have relatively dry skin, reduced skin elasticity, and delayed recovery of barrier function after removal of the stratum corneum which is also present in skin of old people. A feature of skin aging is the change in both water content and barrier function of the skin. We investigated the expression of aquaporin 3 in non sun-exposed human skin, normal human keratinocytes and fibroblasts from different age groups to further understand the relationship between AQP3 and intrinsic skin aging.

We investigated the expression of aquaporin3 (AQP3) in normal human skin, normal human epidermal keratinocytes (NHEK) and skin fibroblast of different ages by immunohistochemistry, immunocytochemistry, the reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. The samples were derived from 60 patients of varying ages: <20 years of age, 30-45 years and >60 years of age. Twenty skin biopsies, 6 for keratinocyte/fibroblast cultures, were taken from each age group.

AQP3 decreased with increasing age in both skin and NHEK samples. We demonstrated significant differences in AQP3 expression between the 3 age groups (P < 0.05). In fibroblasts, AQP3 expression levels were significantly lower in the >60 year olds compared to 30-45 year olds (P < 0.05) and <20 year olds (P < 0.05), there was no significant difference between the two younger groups (P > 0.05).

AQP3 may be involved in the intrinsic aging process of non sun-exposed human skin.