Beta-adrenergic agonists that down-regulate receptor mRNA up-regulate a M(r) 35,000 protein(s) that selectively binds to beta-adrenergic receptor mRNAs.
In an effort to explore the molecular basis for agonist-induced destabilization of beta-adrenergic receptor mRNA, we investigated the nature of RNA-binding proteins both in untreated and agonist-treated DDT1-MF2 smooth muscle cells. Messenger RNAs for the alpha 1b-, beta 1-, and beta 2-adrenergic receptors as well as for beta-globin were transcribed in vitro, incubated with cytosolic fractions, covalently cross-linked by short-wave UV light, and analyzed by SDS-polyacrylamide gel electrophoresis. A prominent M(r) 35,000 radiolabeled protein(s) with the following characteristics was identified: (i) binds selectively to beta 1- and beta 2-adrenergic receptor mRNAs, both of which undergo agonist-induced down-regulation; (ii) does not bind to either alpha 1b-adrenergic receptor mRNA, which does not undergo agonist induced down-regulation, or to beta-globin mRNA; (iii) displays binding to beta 2-adrenergic receptor mRNA that is selectively competed by poly(U) RNA, but not poly(A), -(C), or -(G) RNA; and (iv) displays binding to receptor mRNA that can be competed by RNA harboring destabilizer sequences that are AU-rich and AUUUA pentamer-rich. The abundance of the M(r) 35,000 RNA-binding protein selective for beta-adrenergic receptor message, a factor we term beta ARB protein, varies inversely with the level of receptor mRNA, being induced by agonists that down-regulate receptor mRNA.
Department of Pharmacology, School of Medicine, State University of New York, Stony Brook 11794-8651.
J D
JD
Port
L Y
LY
Huang
C C
CC
Malbon
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D007328:Insulin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008970:Molecular Weight; D011131:Polyribonucleotides / Q000494:pharmacology; D011132:Polyribosomes / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D013329:Structure-Activity Relationship; D014649:Vas Deferens / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D007328:Insulin; D011131:Polyribonucleotides; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011943:Receptors, Adrenergic, beta; D003907:Dexamethasone; D007545:Isoproterenol