Jian-Peng Teoh1, Ahmed S Bayoumi1, Tatsuya Aonuma1, Yanyan Xu1, John A Johnson2, Huabo Su3, Neal L Weintraub4, Yaoliang Tang4, Il-Man Kim5. 1. Vascular Biology Center, Augusta University, Augusta, GA 30912, USA. 2. Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, USA. 3. Vascular Biology Center, Augusta University, Augusta, GA 30912, USA; Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, USA. 4. Vascular Biology Center, Augusta University, Augusta, GA 30912, USA; Department of Medicine, Augusta University, Augusta, GA 30912, USA. 5. Vascular Biology Center, Augusta University, Augusta, GA 30912, USA; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA. Electronic address: ilkim@augusta.edu.
Abstract
RATIONALE: MicroRNAs (miRs) are small, non-coding RNAs that function to post-transcriptionally regulate target genes. First transcribed as primary miR transcripts (pri-miRs), they are enzymatically processed by Drosha into premature miRs (pre-miRs) and further cleaved by Dicer into mature miRs. Initially discovered to desensitize β-adrenergic receptor (βAR) signaling, β-arrestins are now well-appreciated to modulate multiple pathways independent of G protein signaling, a concept known as biased signaling. Using the β-arrestin-biased βAR ligand carvedilol, we previously showed that β-arrestin1 (not β-arrestin2)-biased β1AR (not β2AR) cardioprotective signaling stimulates Drosha-mediated processing of six miRs by forming a multi-protein nuclear complex, which includes β-arrestin1, the Drosha microprocessor complex and a single-stranded RNA binding protein hnRNPA1. OBJECTIVE: Here, we investigate whether β-arrestin-mediated βAR signaling induced by carvedilol could regulate Dicer-mediated miR maturation in the cytoplasm and whether this novel mechanism promotes cardioprotective signaling. METHODS AND RESULTS: In mouse hearts, carvedilol indeed upregulates three mature miRs, but not their pre-miRs and pri-miRs, in a β-arrestin 1- or 2-dependent manner. Interestingly, carvedilol-mediated activation of miR-466g or miR-532-5p, and miR-674 is dependent on β2ARs and β1ARs, respectively. Mechanistically, β-arrestin 1 or 2 regulates maturation of three newly identified βAR/β-arrestin-responsive miRs (β-miRs) by associating with the Dicer maturation RNase III enzyme on three pre-miRs of β-miRs. Myocardial cell approaches uncover that despite their distinct roles in different cell types, β-miRs act as gatekeepers of cardiac cell functions by repressing deleterious targets. CONCLUSIONS: Our findings indicate a novel role for βAR-mediated β-arrestin signaling activated by carvedilol in Dicer-mediated miR maturation, which may be linked to its protective mechanisms.
RATIONALE: MicroRNAs (miRs) are small, non-coding RNAs that function to post-transcriptionally regulate target genes. First transcribed as primary miR transcripts (pri-miRs), they are enzymatically processed by Drosha into premature miRs (pre-miRs) and further cleaved by Dicer into mature miRs. Initially discovered to desensitize β-adrenergic receptor (βAR) signaling, β-arrestins are now well-appreciated to modulate multiple pathways independent of G protein signaling, a concept known as biased signaling. Using the β-arrestin-biased βAR ligand carvedilol, we previously showed that β-arrestin1 (not β-arrestin2)-biased β1AR (not β2AR) cardioprotective signaling stimulates Drosha-mediated processing of six miRs by forming a multi-protein nuclear complex, which includes β-arrestin1, the Drosha microprocessor complex and a single-stranded RNA binding protein hnRNPA1. OBJECTIVE: Here, we investigate whether β-arrestin-mediated βAR signaling induced by carvedilol could regulate Dicer-mediated miR maturation in the cytoplasm and whether this novel mechanism promotes cardioprotective signaling. METHODS AND RESULTS: In mouse hearts, carvedilol indeed upregulates three mature miRs, but not their pre-miRs and pri-miRs, in a β-arrestin 1- or 2-dependent manner. Interestingly, carvedilol-mediated activation of miR-466g or miR-532-5p, and miR-674 is dependent on β2ARs and β1ARs, respectively. Mechanistically, β-arrestin 1 or 2 regulates maturation of three newly identified βAR/β-arrestin-responsive miRs (β-miRs) by associating with the Dicer maturation RNase III enzyme on three pre-miRs of β-miRs. Myocardial cell approaches uncover that despite their distinct roles in different cell types, β-miRs act as gatekeepers of cardiac cell functions by repressing deleterious targets. CONCLUSIONS: Our findings indicate a novel role for βAR-mediated β-arrestin signaling activated by carvedilol in Dicer-mediated miR maturation, which may be linked to its protective mechanisms.
Authors: Il-Man Kim; Sneha Ramakrishna; Galina A Gusarova; Helena M Yoder; Robert H Costa; Vladimir V Kalinichenko Journal: J Biol Chem Date: 2005-04-06 Impact factor: 5.157
Authors: Il-Man Kim; Timothy Ackerson; Sneha Ramakrishna; Maria Tretiakova; I-Ching Wang; Tanya V Kalin; Michael L Major; Galina A Gusarova; Helena M Yoder; Robert H Costa; Vladimir V Kalinichenko Journal: Cancer Res Date: 2006-02-15 Impact factor: 12.701
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