Effects of minoxidil on human skin fibroblasts in culture

Abstract

Collagens are a family of extracellular proteins that have evolved to serve many specialized biologic functions. Fifteen collagen types with at least 18 genetically distinct polypeptide chains have been identified.1 In skin, eight of these collagens make up a major portion of the extracellular matrix including specialized structures such as basement membrane (Type IV collagen) and anchoring fibrils (Type VII collagen). All collagens are synthesized as procollagen precursor molecules. In addition to synthesis and precise association and alignment of the three polypeptide chains, biosynthesis involves many posttranslational modifications.2,3 These include synthesis of hydroxyproline catalyzed by prolyl hydroxylase and synthesis of hydroxylysine catalyzed by lysyl hydroxylase. Hydroxyproline is essential for maximum helical stability, and hydroxylysine participates in collagen cross-link formation as well as synthesis of specific glycosides catalyzed by collagen glycosyl transferases. Other enzymes incorporate into the procollagen molecule complex carbohydrate residues typical of glycoproteins. Following secretion from the cell, amino and carboxyterminal propeptides of the procollagen molecule are cleaved by separate enzymes. Certain lysyl and hydroxylysyl residues are then modified by lysyl oxidase to corresponding aldehydes, which interact with certain hydroxylysine residues to form intermodular cross-links.