UVB irradiation down-regulates type XVI collagen expression in mouse and human skin

Type XVI collagen is a member of the fibril-associated collagens with interrupted triple helices; however, its function or regulation remain unclear.

This study is to examine the effect of ultraviolet B (UVB) or photoaging on type XVI collagen expression in various cultured cells, mouse, and human skin.

The level of α1 (XVI) collagen mRNA was determined by quantitative real-time reverse transcriptase-polymerase chain reaction and the localization of type XVI collagen in normal human skins was detected by theα1 (XVI) collagen polypeptide antibody.

Exposure of keratinocytes resulted in suppression of mRNA level in a dose- and time-dependent manner and in normal fibroblasts or organotypic cocultures was also inhibited. Expression level in hairless mouse skin was decreased by UVB exposure. Messenger RNA level of human skins in the sun-protected area appeared to be greater than that in the sun-exposed area. Sun-protected and sun-exposed normal skin taken from young subjects showed positive immunoreactivities with the anti-α1 (XVI) collagen antibody in the subepidermal region, whereas sun-exposed skin from elderly subjects exhibited negative immunoreaction.

Reduction of type XVI collagen by UVB irradiation in vitro and in vivo may be related to the alteration of extracellular matrix in the photodamaged skin.