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Cell surface expression of C1qR P /CD93 is stabilized by O‐glycosylation
Author(s) -
Park Minha,
Tenner Andrea J.
Publication year - 2003
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.10332
Subject(s) - glycosylation , u937 cell , cell culture , microbiology and biotechnology , phagocytosis , macrophage , cell , biology , chemistry , biochemistry , in vitro , genetics
C1qR P /CD93 is a cell surface receptor predominantly expressed on monocytes, neutrophils, endothelial cells, and early stem cell precursors. In phagocytic cells, it has been characterized as contributing to the enhancement of FcR‐ and CR1‐induced phagocytosis triggered by innate immune system defense collagens such as C1q and mannose binding lectin (MBL). Previously, we demonstrated a high level of glycosylation on C1qR P /CD93 that was predominantly O‐linked. In this study, we investigate the role of glycosylation in C1qR P /CD93 stability first by inhibiting O‐glycosylation by addition of benzyl 2‐acetamido‐2‐deoxy‐α‐ D ‐galactopyranoside (BAG) to the human histiocytic cell line U937, and secondly, by expression of C1qR P /CD93 in the CHO‐derived cell line ldlD which has a reversible defect in protein glycosylation. In both U937 cells and in ldlD cells transfected to express C1qR P /CD93, glycosylation deficiency caused cell surface expression levels of C1qR P /CD93 to decrease, concomitant with the detection of C1qR P /CD93 reactivity in the culture media. Metabolic labeling studies show that when glycosylation is absent, C1qR P /CD93 is synthesized and rapidly released into the culture supernatant or degraded. These studies demonstrate that O‐glycosylation is important in the stable cell surface expression of C1qR P /CD93. J. Cell. Physiol. 196: 512–522, 2003. © 2003 Wiley‐Liss, Inc.