Lipopolysaccharide stimulates the @entity669 phosphorylation of mitogen-activated protein kinases @entity10368 , @entity3903 , and @entity3963 in vascular endothelial cells in a soluble XXXX -dependent manner. Role of protein @entity669 phosphorylation in lipopolysaccharide-induced stimulation of endothelial cells.

@entity1 @entity3275 @entity558 @entity650 @entity12206 @entity5750 @entity326 @entity11704 @entity3963 @entity693 @entity10368 @entity11615 @entity73161 @entity669 @entity291 @entity3903
Vascular endothelial cell (EC) injury or activation by @entity558 plays a critical role in the pathogenesis of Gram-negative @entity693 and @entity326 . EC do not express membrane @entity5750 , but respond to @entity558 in a soluble @entity5750 -dependent manner. The signal transduction mechanisms involved in @entity558 -induced EC responses are largely unknown. We used @entity291 and @entity1 brain microvessel EC (BBMEC, and HBMEC) to study @entity558 -induced protein @entity669 phosphorylation. @entity558 rapidly induced the @entity669 phosphorylation of several proteins in BBMEC and HBMEC, which was detectable by 5 to 15 min, reached a maximum by 30 min, and declined by 60 to 90 min. The increase in @entity669 phosphorylation was apparent following stimulation with @entity558 at 0.1 ng/ml and was dose dependent up to 100 ng/ml. Similar changes in @entity669 phosphorylation were induced by smooth and rough @entity558 as well as @entity3275 , but not by the inactive @entity3275 analogue, @entity11704 @entity73161 . Pretreatment of EC with the @entity669 kinase inhibitor, @entity11615 , inhibited @entity558 -stimulated protein @entity669 phosphorylation and @entity558 -mediated lactic dehydrogenase release from BBMEC and @entity650 release from HBMEC in a dose-dependent manner. Three proteins with apparent m.w. of 44, 42, and 41 kDa were predominant among the @entity558 -induced @entity669 phosphoproteins, and they were identified as mitogen-activated protein kinase isoforms @entity12206 , @entity3963 , and @entity3963 , respectively. @entity558 -induced protein @entity669 phosphorylation in HBMEC and BBMEC was soluble @entity5750 dependent, since pretreatment of these cells with anti- @entity5750 mAb inhibited the @entity558 -induced @entity669 phosphorylation of @entity10368 , @entity3903 , and @entity3963 . Additionally, @entity558 induced a mobility shift in @entity10368 and @entity3903 mitogen-activated protein kinase isozymes, which was inhibited by @entity11615 pretreatment of the EC. These findings demonstrate for the first time that increased protein @entity669 phosphorylation and activation of mitogen-activated protein kinases occur rapidly after @entity558 stimulation of EC in the presence of soluble @entity5750 . Our data also suggest that a @entity11615 -sensitive step, presumably a @entity669 kinase, is involved in mediating @entity558 -induced @entity1 EC activation and @entity650 secretion.
