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Regulation of the mRNA-binding Protein AUF1 by Activation of the β -Adrenergic Receptor Signal Transduction Pathway

1996; Elsevier BV; Volume: 271; Issue: 14 Linguagem: Inglês

10.1074/jbc.271.14.8493

1083-351X

Aldo Pende, Kelli D. Tremmel, Christine T. DeMaria, Burns C. Blaxall, Wayne Minobe, Jonathan A. Sherman, John D. Bisognano, Michael R. Bristow, Gary Brewer, J. David Port,

Mass Spectrometry Techniques and Applications

In both cell culture based model systems and in the failing human heart, β-adrenergic receptors (β-AR) undergo agonist-mediated down-regulation. This decrease correlates closely with down-regulation of its mRNA, an effect regulated in part by changes in mRNA stability. Regulation of mRNA stability has been associated with mRNA-binding proteins that recognize A + U-rich elements within the 3′-untranslated regions of many mRNAs encoding proto-oncogene and cytokine mRNAs. We demonstrate here that the mRNA-binding protein, AUF1, is present in both human heart and in hamster DDT1-MF2 smooth muscle cells and that its abundance is regulated by β-AR agonist stimulation. In human heart, AUF1 mRNA and protein was significantly increased in individuals with myocardial failure, a condition associated with increases in the β-adrenergic receptor agonist norepinephrine. In the same hearts, there was a significant decrease (~50%) in the abundance of β1-AR mRNA and protein. In DDT1-MF2 cells, where agonist-mediated destabilization of β2-AR mRNA was first described, exposure to β-AR agonist resulted in a significant increase in AUF1 mRNA and protein (~ 100%). Conversely, agonist exposure significantly decreased (~40%) β2-adrenergic receptor mRNA abundance. Last, we demonstrate that AUF1 can be immunoprecipitated from polysome-derived proteins following UV cross-linking to the 3′-untranslated region of the human β1-AR mRNA and that purified, recombinant p37AUF1 protein also binds to β1-AR 3′-untranslated region mRNA. In both cell culture based model systems and in the failing human heart, β-adrenergic receptors (β-AR) undergo agonist-mediated down-regulation. This decrease correlates closely with down-regulation of its mRNA, an effect regulated in part by changes in mRNA stability. Regulation of mRNA stability has been associated with mRNA-binding proteins that recognize A + U-rich elements within the 3′-untranslated regions of many mRNAs encoding proto-oncogene and cytokine mRNAs. We demonstrate here that the mRNA-binding protein, AUF1, is present in both human heart and in hamster DDT1-MF2 smooth muscle cells and that its abundance is regulated by β-AR agonist stimulation. In human heart, AUF1 mRNA and protein was significantly increased in individuals with myocardial failure, a condition associated with increases in the β-adrenergic receptor agonist norepinephrine. In the same hearts, there was a significant decrease (~50%) in the abundance of β1-AR mRNA and protein. In DDT1-MF2 cells, where agonist-mediated destabilization of β2-AR mRNA was first described, exposure to β-AR agonist resulted in a significant increase in AUF1 mRNA and protein (~ 100%). Conversely, agonist exposure significantly decreased (~40%) β2-adrenergic receptor mRNA abundance. Last, we demonstrate that AUF1 can be immunoprecipitated from polysome-derived proteins following UV cross-linking to the 3′-untranslated region of the human β1-AR mRNA and that purified, recombinant p37AUF1 protein also binds to β1-AR 3′-untranslated region mRNA.