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Role of EBAG9 protein in coat protein complex I-dependent glycoprotein maturation and secretion processes in tumor cells

Item Type:Article
Title:Role of EBAG9 protein in coat protein complex I-dependent glycoprotein maturation and secretion processes in tumor cells
Creators Name:Wolf, J., Reimer, T.A., Schuck, S., Rueder, C., Gerlach, K., Mueller, E.C., Otto, A., Doerken, B. and Rehm, A.
Abstract:Many proteins mature within the secretory pathway by the acquisition of glycans. Failure to maintain the proper distribution of the glycosylation machinery might lead to disease. High expression levels of the ubiquitous Golgi protein estrogen receptor-binding fragment-associated gene 9 (EBAG9) in human tumors correlate with poor clinical prognosis, and EBAG9 overexpression in epithelial cell lines induces truncated glycans, typical of many carcinomas. Here, we addressed the pathogenetic link between EBAG9 expression and the alteration of the cellular glycome. We applied confocal microscopy, live imaging, pulse-chase labeling in conjunction with immunoprecipitation, and enzymatic activity assays in a variety of EBAG9-overexpressing or depleted epithelial tumor cell lines. EBAG9 shuttles between the ER-Golgi intermediate compartment and the cis-Golgi, and we demonstrate association of EBAG9 with coat protein complex I (COPI)-coated transport vesicles. EBAG9 overexpression imposes delay of endoplasmic reticulum-to-Golgi transport and mislocalizes components of the ER quality control and glycosylation machinery. Conversely, EBAG9 down-regulation accelerates glycoprotein transport through the Golgi and enhances mannosidase activity. Thus, EBAG9 acts as a negative regulator of a COPI-dependent ER-to-Golgi transport pathway in epithelial cells and represents a novel pathogenetic principle in which interference with intracellular membrane trafficking results in the emergence of a tumor-associated glycome.
Keywords:Vesicle Trafficking, Mechanisms of Disease, Tumor Pathogenesis, Secretory Pathway, Immunomodulation
Source:FASEB Journal
Publisher:Federation of American Societies for Experimental Biology
Page Range:4000-4019
Date:October 2010
Official Publication:https://doi.org/10.1096/fj.09-153452
PubMed:View item in PubMed

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