Li Jiao, Wang Xiao Ming, Wang Qiong, Yang Min, Feng Xiao Cheng, Shen Zong Hou
Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, 130 Dong an Road, Shanghai 200032, China.
Arch Biochem Biophys. 2007 Jul 1;463(1):102-9. doi: 10.1016/j.abb.2007.03.005. Epub 2007 Apr 2.
N-Acetylglucosaminyltransferase-V (GnT-V) is a key enzyme in the processing of N-glycans during synthesis of glycoproteins. We have reported that down-regulating GnT-V could induce endoplasmic reticulum stress (ER stress) in 7721 cells, a human hepatocarcinoma cell line. In a search for mechanisms of ER stress, we found that there was a prominent decline of glucose uptake in antisense GnT-V transfectant, furthermore, a decrease of tri- or tetra-antannary sugar chain of glucose transporter 1 (GLUT1). However, distribution of GLUT1 in antisense GnT-V transfectant was not affected. Glucose deprivation has been known to activate ER stress in tumor cells. Therefore, the data presented in this study indicate that the glycosylation change and decrease of transport activity of GLUT1 may be one possible mechanism of ER stress induced by down-regulating GnT-V, and GnT-V may contribute to the regulation of glucose uptake by modifying glycosylation of GLUT1 in some tumor cells.
N-乙酰葡糖胺基转移酶-V（GnT-V）是糖蛋白合成过程中N-聚糖加工的关键酶。我们曾报道，下调GnT-V可在人肝癌细胞系7721细胞中诱导内质网应激（ER应激）。在探寻ER应激机制的过程中，我们发现反义GnT-V转染子中的葡萄糖摄取显著下降，此外，葡萄糖转运蛋白1（GLUT1）的三或四天线型糖链减少。然而，反义GnT-V转染子中GLUT1的分布未受影响。已知葡萄糖剥夺可激活肿瘤细胞中的ER应激。因此，本研究呈现的数据表明，糖基化变化和GLUT1转运活性降低可能是下调GnT-V诱导ER应激的一种可能机制，并且GnT-V可能通过修饰某些肿瘤细胞中GLUT1的糖基化来促进葡萄糖摄取的调节。
