Spatio-temporal regulation of morphogenesis by heparan sulfate chains

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Heparan sulfate (HS) whose basic backbone structure consists of repeating disaccharide of glucuronosyl glucosamine has astronomical number of different structures by sulfation at different positions and by isomerization of glucuronosyl residue. HS usually locates on the cell surfaces and in the extracellular matrix and its structure alters in a spacio-temporal manner. Most of secretary and soluble cell growth factors, cytokines and morphogens which are well known to be required for important cell activities such as cell proliferation, cell differentiation and cell morphology, for example, FGF and Wnt, have properties to bind to HS. Therefore, we hypothesized that those factors, when they differ, may bind to the HS portions with different structures specifically so that each activity of those factors could be regulated by HS distinctively. In this study we first clarified that different factors actually bind to HS with different O-sulfation positions. We then subjected moue, chicken, Zebrafish, and Drosophila to the alteration of genes for HS O-sulfation enzymes, and observed apparent abnormality of organogenesis and tissue-morphogensis in those animals. We further provided some evidence to show that the observed abnormality was due to altered signalings of those factors which were caused, by the abnormal changes in HS structure. Taken together, our study revealed the occurrence of regulation mechanisms of the activities of cell growth factors and morphogens by HS chains.