Biological Functions of Iduronic Acid in Chondroitin/Dermatan Sulfate.

The presence of iduronic acid in chondroitin/dermatan sulfate changes the properties of the polysaccharides, as it generates a more flexible chain with increased binding potentials. Iduronic acid in chondroitin/dermatan sulfate influences multiple cellular properties such as migration, proliferation, differentiation, angiogenesis and regulation of cytokine/growth factor activities. During pathological conditions such as wound healing, inflammation and cancer iduronic acid has diverse regulatory functions. Iduronic acid is formed by the two epimerases DS-epimerase 1 and DS-epimerase 2 which have different tissue distribution and properties. The role of IdoA in chondroitin/dermatan sulfate is underlined by the vast changes of connective tissue features in patients with a new type of Ehler-Danlos syndrome, adducted thumb-clubfoot syndrome. Future direction of research is to understand the roles of the two epimerases and their interplay with sulfotransferases involved in CS/DS biosynthesis. Further, a better definition of chondroitin/dermatan sulfate functions using different knock-out models is needed. In this review, we focus on the two enzymes responsible for iduronic acid formation and the role of iduronic acid in health and disease. © 2013 The Authors Journal compilation © 2013 FEBS.