N-linked glycosylation at Asn152 on CD147 affects protein folding and stability: promoting tumour metastasis in hepatocellular carcinoma.

Zhen-Yu Liu,Bao-Qing Xu,Yao Meng,Bo Wu,Zhi-Nan Chen,Jian-Li Jiang,Lin Jing,Zhi-Guang Fu,Wan Huang,Peng Lin,Hao-Miao Shen,Jiang-Hua Li,Yang Zhou

doi:10.1038/srep35210

Abstract

Cluster of differentiation 147 (CD147), also known as extracellular matrix metalloproteinase inducer, is a transmembrane glycoprotein that mediates oncogenic processes partly through N-glycosylation modifications. N-glycosylation has been demonstrated to be instrumental for the regulation of CD147 function during malignant transformation. However, the role that site-specific glycosylation of CD147 plays in its defective function in hepatocellular carcinomacells needs to be determined. Here, we demonstrate that the modification of N-glycosylation at Asn152 on CD147 strongly promotes hepatocellular carcinoma (HCC) invasion and migration. After the removal of N-glycans at Asn152, CD147 was more susceptible to degradation by ER-localized ubiquitin ligase-mediated endoplasmic reticulum-associated degradation (ERAD). Furthermore, N-linked glycans at Asn152 were required for CD147 to acquire and maintain proper folding in the ER. Moreover, N-linked glycans at Asn152 functioned as a recognition motif that was directly mediated by the CNX quality control system. Two phases in the retention-based ER chaperones system drove ER-localized CD147 trafficking to degradation. Deletion of N-linked glycosylation at Asn152 on CD147 significantly suppressed in situ tumour metastasis. These data could potentially shed light on the molecular regulation of CD147 through glycosylation and provide a valuable means of developing drugs that target N-glycans at Asn152 on CD147.

Highlights

Promoting tumour cell invasion and metastasis[18]
CD147(N152Q)-EGFP and CD147(N44/152/186Q)-EGFP were detected in a reticular pattern that largely colocalized with the endoplasmic reticulum (ER)-tracker (Fig. 1b), indicating that they were retained in the ER
CD147(N152Q)-EGFP and CD147(N44/152/186Q)-EGFP were detected as a sharp band at approximately 50 kDa, which is thought to represent the ER form

Summary

Introduction

Promoting tumour cell invasion and metastasis[18]. Several mechanisms have been proposed to explain the regulation of CD147 expression, including the following mechanisms: the TGF-β1-CD147 signalling loop in the development of liver fibrosis; the regulatory loop involving miR-22, Sp1, and c-Myc modulating CD147 expression; and the induction of CD147 clustering by galectin-319–21. The modification of CD147 by N-glycosylation has been demonstrated to be instrumental for the regulation of CD147 function during malignant transformation[22]. A study in our laboratory that resolved the crystal structure of CD147 identified three N-linked glycosylation sites on CD147: Asn[44], Asn[152] and Asn18624,25. Conformation and even the physiopathological context of the acceptor tripeptide, some N-glycosylation sites are more important than others in determining the protein’s function. The key N-glycosylation site(s) of CD147 that may be critical for regulatingits functions in HCC remain to be determined. We revealed that the modification of N-glycosylation at Asn[152] is required for the function of CD147. The deletion of N-linked glycosylation at Asn[152] on CD147 significantly suppressed in situ tumour metastasis

Methods

Results

Conclusion