1. Serglycin is a major proteoglycan in polarized human endothelial cells and is implicated in the secretion of the chemokine GROalpha/CXCL1.
- Author
-
Meen AJ, Øynebråten I, Reine TM, Duelli A, Svennevig K, Pejler G, Jenssen T, and Kolset SO
- Subjects
- Cell Polarity drug effects, Decorin metabolism, Endothelial Cells cytology, Gene Expression Regulation drug effects, Glycosides pharmacology, Humans, Plasminogen Activators pharmacology, Secretory Vesicles metabolism, Umbilical Veins cytology, Cell Polarity physiology, Chemokine CXCL1 metabolism, Endothelial Cells metabolism, Gene Expression Regulation physiology, Proteoglycans metabolism, Umbilical Veins metabolism, Vesicular Transport Proteins metabolism
- Abstract
Proteoglycan (PG) expression was studied in primary human umbilical vein endothelial cells (HUVEC). RT-PCR analyses showed that the expression of the PG serglycin core protein was much higher than that of the extracellular matrix PG decorin and the cell surface PG syndecan-1. PG biosynthesis was further studied by biosynthetic [(35)S]sulfate labeling of polarized HUVEC. Interestingly, a major part of (35)S-PGs was secreted to the apical medium. A large portion of these PGs was trypsin-resistant, a typical feature of serglycin. The trypsin-resistant PGs were mainly of the chondroitin/dermatan sulfate type but also contained a minor heparan sulfate component. Secreted serglycin was identified by immunoprecipitation as a PG with a core protein of ∼30 kDa. Serglycin was furthermore shown to be present in perinuclear regions and in two distinct types of vesicles throughout the cytoplasm using immunocytochemistry. To search for possible serglycin partner molecules, HUVEC were stained for the chemokine growth-related oncogene α (GROα/CXCL1). Co-localization with serglycin could be demonstrated, although not in all vesicles. Serglycin did not show overt co-localization with tissue-type plasminogen activator-positive vesicles. When PG biosynthesis was abrogated using benzyl-β-D-xyloside, serglycin secretion was decreased, and the number of vesicles with co-localized serglycin and GROα was reduced. The level of GROα in the apical medium was also reduced after xyloside treatment. Together, these findings indicate that serglycin is a major PG in human endothelial cells, mainly secreted to the apical medium and implicated in chemokine secretion.
- Published
- 2011
- Full Text
- View/download PDF