Increase in β1-6 GlcNAc branching caused by N-acetylglucosaminyltransferase V directs integrin β1 stability in human hepatocellular carcinoma cell line SMMC-7721
Increase in β1-6 GlcNAc branching caused by N-acetylglucosaminyltransferase V directs integrin β1 stability in human hepatocellular carcinoma cell line SMMC-7721
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DOI：
10.1002/jcb.21071
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发表时间：
2007-01-01
影响因子：
4
通讯作者：
Zha, Xiliang
中科院分区：
文献类型：
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作者：
Wang, Liying;Liang, Yulong;Zha, Xiliang
本研究构建了GnT-V失活突变体（Delta cGnT-V），并转染SMMC 7721细胞。Delta cGnT-V转染子（Delta c-7721）中的整合素β 1显示β 1-6 GlcNAc分支数量的衰减，而wtGnT-V转染子（wt-7721）中的整合素β 1呈现富含β 1-6 GlcNAc的模式。WT-7721细胞中整合素β 1的表达高于空载体转染的7721细胞，而Delta cGnT-V的转染降低了整合素β 1的表达，尽管这些细胞系中整合素β 1的mRNA水平没有显著变化。脉冲追踪实验表明，Delta c-7721中整合素β 1降解较快，半衰期小于3 h，而wt-7721中整合素β 1亚基降解较缓，半衰期约为16 h，而模拟细胞中整合素β 1亚基降解速率介于两者之间，约为10 h。在wt-7721中观察到更有效地促进细胞向纤连蛋白迁移和通过基质胶侵入，而这在Delta c-7721中几乎被抑制。我们的研究结果表明，β 1-6 GlcNAc分支的加入导致整合素β 1上更完全糖基化的成熟形式，并抑制β 1蛋白降解。由GnT-V引起的糖基化指导整合素β 1稳定性和更多递送至质膜，随后促进基于Fn的细胞迁移和侵袭。
In this study, an enzymatic inactive mutant of GnT-V (Delta cGnT-V) was constructed and transfected in SMMC 7721 cell line. Integrin beta 1 in Delta cGnT-V transfectants (Delta c-7721) showed attenuation of the number of beta 1-6 GlcNAc branching, whereas those in wtGnT-V transfectants (wt-7721) presented a beta 1-6 GlcNAc-rich pattern. High integrin beta 1 expression was observed in wt-7721 compared with mock cells (7721 cell transfected with the vector pcDNA3), while transfection of Delta cGnT-V decreased the integrin beta 1 expression, despite of no significant changes on integrin beta 1 mRNA level in these cell lines. Pulse-chase experiment showed that Integrin beta 1 in Delta c-7721 was prone to quick degradation and its half-life was less than 3 h, on the contrary, the alleviating degradation of beta 1 subunit was observed in wt-7721 where the beta 1 subunit half-life was about 16 h, meanwhile, the degradation rate of beta 1 subunit in mock cells was in between, about 10 h. More effective in promoting cell migration toward fibronectin and invasion through Matrigel was observed in wt-7721 while this was almost suppressed in Delta c-7721. Our results suggest that the addition of beta 1-6 GlcNAc branching caused more fully glycosylated mature form on integrin beta 1 and inhibited beta 1 protein degradation. Glycosylation caused by GnT-V directs integrin beta 1 stability and more delivery to plasma membrane, subsequently promotes Fn-based cell migration and invasion.