Collagen XVI is expressed by human dermal fibroblasts and keratinocytes and is associated with the microfibrillar apparatus in the upper papillary dermis

Indirect immunofluorescence staining of normal skin with affinity-purified antibodies revealed a conspicuous presence of collagen XVI at the dermo-epi dermal interface where it occurs in close vicinity to collagen VII. In addi tion, the protein co-localizes with fibrillin 1 at the cutaneous basement m embrane zone and the adjacent papillary dermis, but not in deeper layers of the dermis, Both fibronectin and collagen XVI are distributed throughout s mooth muscles of hair follicles but do not co-localize. These data suggest, therefore, that collagen XVI contributes to the structural integrity of th e dermo-epidermal junction zone by interacting with components of the ancho ring complexes and the microfibrillar apparatus. A strong immunofluorescenc e signal associated with the extracellular matrix of individual cells was o bserved for keratinocytes or fibroblasts in monolayer cultures. Therefore, both cell types are likely sources of the protein also in situ. The rate of expression of collagen XVI mRNA in keratinocytes is about half of that in normal human skin fibroblasts. In both cell types, TGF-beta 2 treatment res ults in an up-regulation of the collagen XVI-mRNA by approximately 50%. In keratinocytes, synthesis of collagen XVI protein and deposition to the cell layer and the extracellular matrix is stimulated fivefold and twofold, res pectively. Since TGF-beta 2 also upregulates the biosynthesis of other matr ix macromolecules in the subepidermal zone the factor is likely to contribu te to the stabilization of matrix zones near basement membranes in healing wounds. (C) 1999 Elsevier Science B.V./International Society of Matrix Biol ogy. All rights reserved.