Chondroitin 4-O-sulfotransferase-1 modulates Wnt-3a signaling through control of E disaccharide expression of chondroitin sulfate
Chondroitin 4-O-sulfotransferase-1 modulates Wnt-3a signaling through control of E disaccharide expression of chondroitin sulfate
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DOI：
10.1074/jbc.m802997200
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发表时间：
2008-10-03
影响因子：
4.8
通讯作者：
Kitagawa, Hiroshi
中科院分区：
文献类型：
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作者：
Nadanaka, Satomi;Ishida, Miho;Kitagawa, Hiroshi
Wnt-3a是激活Wnt信号传导中的β-连环蛋白依赖性途径的配体，其涉及许多生理事件，如形态发生。到目前为止，硫酸乙酰肝素（HS）蛋白聚糖已被强调为含有Wnt的形态发生剂的低亲和力受体。在这里，我们显示的重要性，硫酸软骨素（CS）蛋白聚糖在Wnt-3a的有效信号和结构特征的CS所需的Wnt-3a信号的调节。Wnt-3a信号在小鼠L细胞突变体sog 9中被抑制，与亲本L细胞相比，sog 9在编码HS合成酶的EXT 1基因和软骨素4-O-磺基转移酶（C4 ST-1）基因中有缺陷。用C4 ST-1转染sog 9细胞导致Wnt-3a信号的恢复，而在sog 9细胞中表达EXT 1不能恢复Wnt-3a信号。此外，引入的C4 ST-1的表达水平与Wnt-3a信号传导的恢复相关，伴随着CS的E二糖单元的表达增加。有趣的是，使用Biacore进行的分子相互作用分析显示，鱿鱼CS-E（富含E二糖单元）与Wnt-3a的结合强度（Kd = 13.2 nM）与来自牛肺的肝素（Kd = 8.43 nM）的结合程度相同。相比之下，其他CS异构体以及从牛肾分离的HS显示出对Wnt-3a几乎没有结合活性。此外，外源性添加CS-E有效地抑制Wnt-3a诱导的β-连环蛋白的积累。这些结果表明C4 ST-1合成的CS-E样结构参与Wnt-3a信号传导并调节Wnt-3a信号引起的生理事件。
Wnt-3a is a ligand that activates the beta-catenin-dependent pathway in Wnt signaling, which is implicated in numerous physiological events such as morphogenesis. So far, heparan sulfate (HS) proteoglycans have been highlighted as a low affinity receptor for morphogens containing Wnts. Here we show the importance of chondroitin sulfate (CS) proteoglycans in the efficient signaling of Wnt-3a and the structural features of CS required for the regulation of Wnt-3a signaling. Wnt-3a signaling was depressed in a mouse L cell mutant, called sog9, which is defective in the EXT1 gene encoding the HS-synthesizing enzyme and the chondroitin 4-O-sulfotransferase (C4ST-1) gene compared with parental L cells. The transfection of sog9 cells with C4ST-1 resulted in the recovery of Wnt-3a signaling, whereas the expression of EXT1 in sog9 cells could not restore Wnt-3a signaling. In addition, the expression level of introduced C4ST-1 correlated with the recovery of Wnt-3a signaling accompanied by the increased expression of the E disaccharide unit of CS. Interestingly, molecular interaction analyses using Biacore revealed that squid CS-E (rich in the E disaccharide unit) bound strongly to Wnt-3a (K-d = 13.2 nM) to the same extent as heparin from bovine lung (K-d = 8.43 nM). In contrast, other CS isoforms as well as HS isolated from bovine kidney showed little binding activity to Wnt-3a. Moreover, exogenously added CS-E potently inhibited the accumulation of beta-catenin induced by Wnt-3a. These results suggest that CS-E-like structures synthesized by C4ST-1 participate in Wnt-3a signaling and modulate the physiological events caused by Wnt-3a signals.