期刊
TRAFFIC
卷 10, 期 4, 页码 438-450出版社
WILEY
DOI: 10.1111/j.1600-0854.2009.00882.x
关键词
brush border membrane; DRMs; enterocyte-like cells; galectin-4; glycosylation
类别
资金
- Institut National de la SantE et de la Recherche MEdicale (INSERM)
- Centre National de la Recherche Scientifique (CNRS)
- Ministere de la Recherche et de l'Enseignement SupErieur
- European Community (FEDER)
- Region Nord-Pas de Calais (France)
- Universite des Sciences et Technologies de Lille I
We have previously reported that silencing of galectin-4 expression in polarized HT-29 cells perturbed apical biosynthetic trafficking and resulted in a phenotype similar to the inhibitor of glycosylation, 1-benzyl-2-acetamido-2-deoxy-beta-d-galactopyranoside (GalNAc alpha-O-bn). We now present evidence of a lipid raft-based galectin-4-dependent mechanism of apical delivery of glycoproteins in these cells. First, galectin-4 recruits the apical glycoproteins in detergent-resistant membranes (DRMs) because these glycoproteins were depleted in DRMs isolated from galectin-4-knockdown (KD) HT-29 5M12 cells. DRM-associated glycoproteins were identified as ligands for galectin-4. Structural analysis showed that DRMs were markedly enriched in a series of complex N-glycans in comparison to detergent-soluble membranes. Second, in galectin-4-KD cells, the apical glycoproteins still exit the Golgi but accumulated inside the cells, showing that their recruitment within lipid rafts and their apical trafficking required the delivery of galectin-4 at a post-Golgi level. This lectin that is synthesized on free cytoplasmic ribosomes is externalized from HT-29 cells mostly in the apical medium and follows an apical endocytic-recycling pathway that is required for the apical biosynthetic pathway. Together, our data show that the pattern of N-glycosylation of glycoproteins serves as a recognition signal for endocytosed galectin-4, which drives the raft-dependent apical pathway of glycoproteins in enterocyte-like HT-29 cells.
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