Serglycin in Quiescent and Proliferating Primary Endothelial Cells

Abstract

Proteoglycans are fundamental components of the endothelial barrier, but the functions of the proteoglycan serglycin in endothelium are less described. Our aim was to describe the roles of serglycin in processes relevant for endothelial dysfunction. Primary human umbilical vein endothelial cells (HUVEC) were cultured in vitro and the expression of proteoglycans was investigated. Dense cell cultures representing the quiescent endothelium coating the vasculature was compared to sparse activated cell cultures, relevant for diabetes, cancer and cardiovascular disease. Secretion of 35S- proteoglycans increased in sparse cultures, and we showed that serglycin is a major component of the cell-density sensitive proteoglycan population. In contrast to the other proteoglycans, serglycin expression and secretion was higher in proliferating compared to quiescent HUVEC. RNAi silencing of serglycin inhibited proliferation and wound healing, and serglycin expression and secretion was augmented by hypoxia, mechanical strain and IL-1β induced inflammation. Notably, the secretion of the angiogenic chemokine CCL2 resulting from IL-1β activation, was increased in serglycin knockdown cells, while angiopoietin was not affected. Both serglycin and CCL2 were secreted predominantly to the apical side of polarized HUVEC, and serglycin and CCL2 co-localized both in perinuclear areas and in vesicles. These results suggest functions for serglycin in endothelial cells trough interactions with partner molecules, in biological processes with relevance for diabetic complications, cardiovascular disease and cancer development.

Glucosamine exposure reduces proteoglycan synthesis in primary human endothelial cellsin vitro

“…2 a, left panel). This is in accordance with previous studies ( 10 ). The cell fraction, in contrast, mainly contained the high molecular weight component ( Fig.…”

“…These different PGs might have different functions and responses to GlcN. We have demonstrated that the extracellular matrix PGs perlecan and decorin are highly expressed in HUVEC ( 10 ). Western blotting was performed on untreated, cABC treated and HNO 2 -treated medium fractions with antibodies against the CS/DS PG decorin and the HSPG perlecan.…”

Epigenetic Regulation of the Biosynthesis & Enzymatic Modification of Heparan Sulfate Proteoglycans: Implications for Tumorigenesis and Cancer Biomarkers

“…HSPGs that are located at the cell surface are also involved in the establishment of morphogen and chemokine gradients important in WBC extravasation, but are also vital during development [ 28 , 29 , 30 ]. HSPGs located within secretory vesicles are involved in the packaging of vesicular contents, maintenance of protease activity, and regulating various activities upon secretion, such as host defense mechanisms and wound repair (e.g., [ 22 , 31 , 32 , 33 ]). Membrane-associated HSPGs are also involved as receptors or coreceptors on the cell surface promoting a variety of activities: (1) they can function as coreceptors for growth factor receptors, mediating signal transduction pathways (e.g., [ 34 , 35 , 36 ]); (2) they can function as endocytic receptors, facilitating the transcytosis and/or clearance of lipoproteins [ 37 , 38 ] and promoting exosome uptake [ 39 , 40 ]; (3) they can cooperate with cell adhesion molecules, such as integrins, to affect cellular migration (e.g., [ 27 , 41 , 42 ]); (4) they can bind to and regulate the activity of matrix metalloproteases within the ECM (e.g., [ 43 ]); and (5) they can act to mediate cytokine-induced signal transduction pathways (e.g., [ 44 , 45 ]) ( Figure 1 A).…”

Insight into the role of chondroitin sulfate E in angiogenesis

“…In endothelial cells, serglycin is the major CS‐PG stored intracellularly and secreted mainly to the apical side in proliferating endothelial cells or upon stimulation. Through its GAG chains, it binds chemokines, such as CXCL1 and CCL2 , potentially offering protection, transport and presentation of these molecules either in the endothelial cells themselves or other cells . However, further work needs to be done to determine the specific CS structures on endothelial cell serglycin and their biological significance.…”