Feng Lei, Jiang Hao, Wu Peng, Marlow Florence L
Department of Biochemistry, Albert Einstein College of Medicine Yeshiva University, Bronx, NY 10461, USA.
Department of Biochemistry, Albert Einstein College of Medicine Yeshiva University, Bronx, NY 10461, USA.
Dev Biol. 2014 Nov 15;395(2):268-86. doi: 10.1016/j.ydbio.2014.09.010. Epub 2014 Sep 18.
L-fucose, a monosaccharide widely distributed in eukaryotes and certain bacteria, is a determinant of many functional glycans that play central roles in numerous biological processes. The molecular mechanism, however, by which fucosylation mediates these processes remains largely elusive. To study how changes in fucosylation impact embryonic development, we up-regulated N-linked fucosylation via over-expression of a key GDP-Fucose transporter, Slc35c1, in zebrafish. We show that Slc35c1 overexpression causes elevated N-linked fucosylation and disrupts embryonic patterning in a transporter activity dependent manner. We demonstrate that patterning defects associated with enhanced N-linked fucosylation are due to diminished canonical Wnt signaling. Chimeric analyses demonstrate that elevated Slc35c1 expression in receiving cells decreases the signaling range of Wnt8a during zebrafish embryogenesis. Moreover, we provide biochemical evidence that this decrease is associated with reduced Wnt8 ligand and elevated Lrp6 coreceptor, which we show are both substrates for N-linked fucosylation in zebrafish embryos. Strikingly, slc35c1 expression is regulated by canonical Wnt signaling. These results suggest that Wnt limits its own signaling activity in part via up-regulation of a transporter, slc35c1 that promotes terminal fucosylation and thereby limits Wnt activity.
L-岩藻糖是一种广泛分布于真核生物和某些细菌中的单糖，是许多功能性聚糖的决定因素，这些聚糖在众多生物过程中发挥着核心作用。然而，岩藻糖基化介导这些过程的分子机制在很大程度上仍然不清楚。为了研究岩藻糖基化的变化如何影响胚胎发育，我们通过在斑马鱼中过表达关键的GDP-岩藻糖转运蛋白Slc35c1来上调N-连接岩藻糖基化。我们发现，Slc35c1的过表达导致N-连接岩藻糖基化升高，并以转运蛋白活性依赖的方式破坏胚胎模式形成。我们证明，与增强的N-连接岩藻糖基化相关的模式缺陷是由于经典Wnt信号减弱所致。嵌合分析表明，在斑马鱼胚胎发育过程中，接受细胞中Slc35c1表达的升高会降低Wnt8a的信号传导范围。此外，我们提供了生化证据，表明这种降低与Wnt8配体减少和Lrp6共受体升高有关，我们发现这两者都是斑马鱼胚胎中N-连接岩藻糖基化的底物。引人注目的是，slc35c1的表达受经典Wnt信号的调节。这些结果表明，Wnt部分地通过上调一种转运蛋白slc35c1来限制其自身的信号活性，该转运蛋白促进末端岩藻糖基化，从而限制Wnt活性。
