Regulation of prostaglandin H synthase-2 expression in cerebromicrovascular smooth muscle by serum and epidermal growth factor.
Growth factors may play a role in the formation of prostaglandins (PG) by cerebral blood vessels during development or reaction to injury. In smooth muscle cultures isolated from murine cerebral microvessels PG production was induced with either serum or epidermal growth factor (EGF). Prostaglandin H synthase (PGHS) activity peaked at 6 h after the addition of 10% serum or 50 ng/ml EGF. Increases in expression of PGHS-1 mRNA were small (7- to 10-fold) compared with PGHS-2 (30- to 120-fold), and the induction patterns were different for serum and EGF. An increase in PGHS-2 message was detected by 0.5 h of adding either agent, but peak induction occurred earlier for EGF than for serum, 1 h vs. 3 h, respectively. The response to either stimulus had returned to prestimulation levels by 12 h. The induction of PGHS-2 protein was also transient, but followed a more delayed time course (peak levels at 6 h). Induction of activity, message, and protein by either agent was blocked by 1 microM dexamethasone and attenuated by genistein (100 microM), a nonspecific tyrosine kinase inhibitor. Tyrphostin 47, a more selective EGF receptor tyrosine kinase inhibitor, dose-dependently inhibited EGF-stimulated PGHS activity, completely abolishing PG production at 100 microM. However, this inhibitor had no effect on serum-stimulated PG production. Curiously, 100 microM tyrphostin 47 enhanced EGF-induced PGHS-2 mRNA and protein expression. These data suggest that EGF induces the expression of PGHS-2 in cerebromicrovascular smooth muscle by a mechanism that requires tyrosine kinase activity and that is distinct from serum.
Department of Pathology, The University of Iowa, Iowa City 52242-1181, USA.
G
G
Rich
E J
EJ
Yoder
S A
SA
Moore
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001798:Blood Proteins / Q000494:pharmacology*; D001921:Brain / Q000098:blood supply; D002196:Capillaries / Q000166:cytology; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D019833:Genistein / Q000494:pharmacology; D005938:Glucocorticoids / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D001798:Blood Proteins; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005938:Glucocorticoids; D009578:Nitrobenzenes; D012333:RNA, Messenger; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D004815:Epidermal Growth Factor; D003907:Dexamethasone; D019833:Genistein; D011451:Prostaglandin-Endoperoxide Synthases; D011505:Protein-Tyrosine Kinases