Studies on molecular mechanisms of mammalian early embryonic development by means of recessive lethal mutations.

我们鉴定了小鼠ext2的转基因插入等位基因，这是人类多发性遗传性外骨病的致病基因之一，它催化HS链的延长。对Ext2基因缺陷胚胎的标记表达分析表明，HS链对成纤维细胞生长因子信号的应答是必不可少的，尤其是对成纤维细胞生长因子配体的局部分布和成纤维细胞生长因子信号的应答。此外，附着在细胞表面的HS链的表达对于那些可能激活成纤维细胞生长因子信号的区域具有明显的特异性。毛发

We identified the transgene insertion allele of mouse Ext2, one of the causative genes of human multiple hereditaryexostoses, which catalyzes elongation of HS-chains. Marker expression analyses of Ext2-deficient embryos revealed that HS-chains are essential for response to Fibroblast growth factor (FGF) signaling and, in particular, local distribution of the FGF ligands as well as FGF signaling. Moreover, HS-chains expression attached with cell surface is distinctively specific to those areas in which FGF signaling is potentially active. Fur