Wheat germ agglutinin inhibits thrombin-induced rises in cytosolic free calcium and prostacyclin synthesis by human umbilical vein endothelial cells
✍ Scribed by Dr. Jürgen Grulich-Henn; Babette B. Weksler; Kentaro Watanabe; Eric A. Jaffe
- Publisher
- John Wiley and Sons
- Year
- 1988
- Tongue
- English
- Weight
- 529 KB
- Volume
- 137
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
To characterize the endothelial cell surface membrane glycoproteins that mediate thrombin stimulation of PGI2 synthesis by human umbilical vein endothelial cells (HUVEC), HUVEC were stimulated with thrombin in the presence or absence of different lectins. Of the lectins tested, only wheat germ agglutinin (WGA) inhibited thrombin-induced rises in cytosolic free calcium ([CaL+],), measured using Quin 2-loaded HUVEC and PG12 production measured by radioimmunoassay. However, WGA by itself had no influence on baseline [Ca2+Ii or PGI2 production and did not inhibit histamine-induced rises in [Ca2+],. The inhibition of thrombin-induced rises in [Ca2+li and PGll production by WGA was dose dependent, with half-maximal inhibition occurring at 2 pg/ml. WCA also inhibited thrombin-induced release of 3H-arachidonic acid. These effects of WGA were reversed by N-acetyl-glucosamine (GlcNAc) and N-acetylneuraminic acid, which bind specifically to WGA, but not by unrelated sugars. Succinylated WGA (succ-WGA), a chemically modified derivative of WGA that binds to GlcNAc but, unlike native WCA, not to sialoglycoproteins, did not inhibit thrombin-induced rises in [Ca"], and PGI2 production, These results suggest that thrombin induces rises in ICa2+], and PCf2 production by interacting with an endothelial surface membrane sialoglycoprotein.