Yamada Shuhei, Onishi Masako, Fujinawa Reiko, Tadokoro Yuko, Okabayashi Koji, Asashima Makoto, Sugahara Kazuyuki
Laboratory of Proteoglycan Signaling and Therapeutics, Hokkaido University Graduate School of Life Science, Sapporo 001-0021, Japan.
Glycobiology. 2009 May;19(5):488-98. doi: 10.1093/glycob/cwp005. Epub 2009 Feb 3.
Xenopus laevis is an excellent animal for analyzing early vertebrate development. Various effects of glycosaminoglycans (GAGs) on growth factor-related cellular events during embryogenesis have been demonstrated in Xenopus. To elucidate the relationship between alterations in fine structure and changes in the specificity of growth factor binding during Xenopus development, heparan sulfate (HS) and chondroitin/dermatan sulfate (CS/DS) chains were isolated at four different embryonic stages and their structure and growth factor-binding capacities were compared. The total amounts of both HS and CS/DS chains decreased from the pre-midblastula transition to the gastrula stage, but increased exponentially during the following developmental stages. The length of HS chains was not significantly affected by development, whereas that of CS/DS chains increased with development. The disaccharide composition of GAGs in embryos also changed during development. The degree of sulfation of the HS chains gradually decreased with development. The predominant sulfation position in the CS/DS chains shifted from C4 to C6 of GalNAc during embryogenesis. Growth factor-binding experiments using a BIAcore system demonstrated that GAGs bound growth factors including fibroblast growth factors-1 and -2, midkine, and pleiotrophin, with comparable affinities. These affinities significantly varied during development, although the correlation between the structural alterations of GAGs and the change in the ability to bind growth factors remains to be clarified. The expression of saccharide sequences, which specifically interact with a growth factor, might be regulated during development.
非洲爪蟾是分析早期脊椎动物发育的优良动物。在非洲爪蟾中，已证明糖胺聚糖（GAGs）在胚胎发生过程中对生长因子相关细胞事件具有多种影响。为阐明非洲爪蟾发育过程中精细结构改变与生长因子结合特异性变化之间的关系，在四个不同胚胎阶段分离了硫酸乙酰肝素（HS）和硫酸软骨素/硫酸皮肤素（CS/DS）链，并比较了它们的结构和生长因子结合能力。从囊胚中期前过渡到原肠胚阶段，HS和CS/DS链的总量均减少，但在随后的发育阶段呈指数增加。HS链的长度不受发育的显著影响，而CS/DS链的长度随发育增加。胚胎中GAGs的二糖组成在发育过程中也发生变化。HS链的硫酸化程度随发育逐渐降低。在胚胎发生过程中，CS/DS链中主要的硫酸化位置从GalNAc的C4转移到C6。使用BIAcore系统进行的生长因子结合实验表明，GAGs以相当的亲和力结合包括成纤维细胞生长因子-1和-2、中期因子和多效生长因子在内的生长因子。尽管GAGs的结构改变与结合生长因子能力变化之间的相关性仍有待阐明，但这些亲和力在发育过程中显著不同。与生长因子特异性相互作用的糖序列的表达可能在发育过程中受到调控。
