ASSOCIATION OF HEPATIC BETA(2)-ADRENERGIC RECEPTOR GENE TRANSCRIPT DESTABILIZATION DURING POSTNATAL-DEVELOPMENT IN THE SPRAGUE-DAWLEY RAT WITH A M(R)-85,000 PROTEIN THAT BINDS SELECTIVELY TO THE BETA(2)-ADRENERGIC RECEPTOR MESSENGER-RNA 3'-UNTRANSLATED REGION

In the liver, transcript destabilization contributes to the decrease i n steady-state levels of beta(2)-adrenergic receptor mRNA that occurs during early postnatal development in the rat. From genomic DNA, polym erase chain reaction (PCR) was used to amplify a 718-basepair (bp) fra gment of the beta(2)-adrenergic receptor gene including the entire 3'- untranslated region. Results from SDS-gel electrophoresis and autoradi ography demonstrated a M(r) 85,000 cellular factor present in postnata l day 60, but not fetal day 18 rat liver that was ultraviolet (UV) lig ht-crosslinked to in vitro transcribed beta(2)-adrenergic receptor RNA 3'-untranslated region. Unlabeled beta(2)-adrenergic receptor RNA 3'- untranslated region, but not mouse beta-actin RNA, competed with label ed beta(2)-adrenergic receptor RNA 3'-untranslated region for binding to the M(r) 85,000 protein. Cross-linking of the beta(2)-adrenergic re ceptor RNA 3'-untranslated region to the M(r) 85,000 protein was inhib ited by the ribohomopolymer poly(U), with poly(A), poly(C) and poly(C) having little or no effect. Thus, a M(r) 85,000 protein has been iden tified in adult male rat liver that may interact with U-rich sequences in the 3'-untranslated region of the beta(2)-adrenergic receptor mRNA and may account for the decreased stability of hepatic beta(2)-adrene rgic receptor gene transcripts that occurs during development. (C) 199 5 Wiley-Liss, Inc.