Mutation of N-linked glycosylation at Asn548 in CD133 decreases its ability to promote hepatoma cell growth
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Ying Liu1,*, Shifang Ren1,*, Liqi Xie2, Chunhong Cui1, Yang Xing1, Chanjuan Liu1, Benjin Cao1, Fan Yang1, Yinan Li1, Xiaoning Chen1, Yuanyan Wei1, Haojie Lu2 and Jianhai Jiang1
1 Key Laboratory of Glycoconjuates Research, Ministry of Public Health and Gene Research Center, Department of Biochemistry and Molecular Biology, Shanghai Medical College of Fudan University, Shanghai, People’s Republic of China
2 Institutes of Biomedical Sciences of Fudan University, Shanghai, People’s Republic of China
* These authors have contributed equally to this work
Jianhai Jiang, email:
Haojie Lu, email:
Yuanyan Wei, email:
Keywords: N-linked glycosylation, CD133, hepatoma, cell growth
Received: February 11, 2015 Accepted: April 20, 2015 Published: May 12, 2015
The membrane glycoprotein CD133 is a popular marker for cancer stem cells and contributes to cancer initiation and invasion in a number of tumor types. CD133 promotes tumorigenesis partly through an interaction between its phosphorylated Y828 residue and the PI3K regulatory subunit p85, and the interaction with β-catenin. Although CD133 glycosylation is supposed to be associated with its function, the contribution of N-glycosylation to its functions remains unclear. Here we analyzed the exact site(s) of N-glycosylation in CD133 by mass spectrometry and found that all eight potential N-glycosylation sites of CD133 could be indeed occupied by N-glycans. Loss of individual N-glycosylation sites had no effect on the level of expression or membrane localization of CD133. However, mutation at glycosylation site Asn548 significantly decreased the ability of CD133 to promote hepatoma cell growth. Furthermore, mutation of Asn548 reduced the interaction between CD133 and β-catenin and inhibited the activation of β-catenin signaling by CD133 overexpression. Our results identified the characteristics and function of CD133 glycosylation sites. These data could potentially shed light on molecular regulation of CD133 by glycosylation and enhance our understanding of the utility of glycosylated CD133 as a target for cancer therapies.
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