Differential Expression of α1 and α2 Chains of Type VI Collagen in the Upper, Middle, and Lower Dermal Fibroblasts In Vitro

Abstract

Levels of type VI collagen mRNAs were determined in cultured skin fibroblasts derived from the upper, middle, and lower layers. The level of alpha 1 (VI) collagen mRNA was the highest in the fibroblasts from the upper layer. In contrast, alpha 2 (VI) collagen mRNA level in the fibroblasts from the lower layer predominated over those in the upper and middle layers. The level of alpha 3 (VI) collagen mRNA was the same in the three dermal layers. When the fibroblasts from the upper layer were passaged successively, the alpha 1 (VI) collagen mRNA level declined and alpha 2 (VI) collagen mRNA level increased to those of the lower dermal fibroblasts. These results indicate that alpha 1 (VI) and alpha 2 (VI) collagen expressions in skin fibroblast cultures are heterogeneous and that successive passages of the upper dermal fibroblasts may result in transition of the phenotype of alpha 1 (VI) and alpha 2 (VI) expression to that of lower dermal fibroblasts. The modulation of the expression of alpha 1 (VI) and alpha 2 (VI) chains presumably reflects the process of cellular aging in vitro and should be a useful biochemical marker in studies of cell aging.