Immediate-early MEK-1-dependent stabilization of rat smooth muscle cell cyclooxygenase-2 mRNA by Galpha(q)-coupled receptor signaling.
Activation of Galpha(q)-coupled P2Y nucleotide receptors strongly (>100-fold) induces the rat vascular smooth muscle cell cyclooxygenase-2 (COX-2) mRNA, yet transcription is induced only approximately 3-fold over 1 h. Intact cell decay analysis of tetracycline-suppressible luciferase chimera mRNAs shows that regulated stabilization of the intrinsically unstable mRNA contributes to this response. Deletion mapping of the 2468-base COX-2 mRNA 3'-untranslated region (UTR) shows that a distal, 130-base AU-rich region functions as a cis-acting regulated stabilization response element, which under basal conditions serves as the dominant instability determinant for the 3'-UTR. Regulation of this response is through the p42/44 MAP kinases, whereas the p38 MAP kinases are not involved. The stabilization response element binds avidly and specifically to a prominent nuclear-enriched approximately 90-kDa factor and several less abundantly labeled mRNA binding proteins that are unaffected by P2Y receptor signaling. Although other instability determinants are located throughout the rat COX-2 mRNA 3'-UTR, mitogen signaling only interferes with rapid decay mediated by its most distal 130 bases. A complex of nuclear factors that bind this mRNA region specifically may include candidate targets for regulatory modulation. These observations support the general notion that the rapid induction of immediate-early gene expression through mitogenic receptors involves simultaneous activation of transcriptional and post-transcriptional mechanisms.
Xu
K
K
Department of Pharmacology and Graduate Program in Molecular and Systems Pharmacology, Graduate Division of Biomedical and Biological Sciences, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Robida
A M
AM
Murphy
T J
TJ
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D017931:DNA Primers; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005822:Genetic Vectors; D007527:Isoenzymes / Q000235:genetics*; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction
D017931:DNA Primers; D007527:Isoenzymes; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D019204:GTP-Binding Proteins