Composition and organization of the extracellular matrix of vein walls: collagen networks

As there are few recent reports concerning the structure and exact composition of the extracellular matrix from human normal and varicose veins, we carried out comparative immunohistochemical analysis of vessel wall using conventional and confocal laser scanning immunofluorescence techniques. The present report is a rapid review of the structure and function of the 19 known collagen types and our first results on the distribution of collagen types VI, XII and XIV and laminin (glycoprotein from basement membrane) in vein walls. Type VI collagen is concentrated in the sub-endothelium and widely distributed in the media and adventice. For the first time, we demonstrated that both FACIT (fibril-associated) collagens XII and XIV were present in the vein wall, but at different anatomic sites.

Analysis of the role of the COL1 domain and its adjacent cysteine-containing sequence in the chain assembly of type IX collagen

The mechanisms of chain selection and assembly of type IX collagen, a heterotrimer alpha 1(IX)alpha 2(IX)alpha 3(IX), must differ from that of fibrillar collagens since it lacks the characteristic C-propeptide of these latter molecules. We have tested the hypothesis that the information required for this process is contained within the C-terminal triple helical disulfide-bonded region (LMW). The reassociations of the purified LMW fragments of pepsinized bovine type IX collagen were followed by the formation of disulfide-bonded multimers. Our data demonstrate that only three triple helical assemblies form readily, (alpha 1)3, (alpha 2)3 and alpha 1 alpha 2 alpha 3. The information required for chain selection and assembly is thus, at least in part, contained in the studied fragments. Molecular stoichiometries different from the classical heterotrimer may thus also form under certain conditions.