Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1963821 | Cellular Signalling | 2011 | 10 Pages |
Abstract
Both β1- and β3-adrenergic receptors (β1ARs and β3ARs) are present on nuclear membranes in adult ventricular myocytes. These nuclear-localized receptors are functional with respect to ligand binding and effector activation. In isolated cardiac nuclei, the non-selective βAR agonist isoproterenol stimulated de novo RNA synthesis measured using assays of transcription initiation (Boivin et al., 2006 Cardiovasc Res. 71:69-78). In contrast, stimulation of endothelin receptors, another G protein-coupled receptor (GPCR) that localizes to the nuclear membrane, resulted in decreased RNA synthesis. To investigate the signalling pathway(s) involved in GPCR-mediated regulation of RNA synthesis, nuclei were isolated from intact adult rat hearts and treated with receptor agonists in the presence or absence of inhibitors of different mitogen-activated protein kinase (MAPK) and PI3K/PKB pathways. Components of p38, JNK, and ERK1/2 MAP kinase cascades as well as PKB were detected in nuclear preparations. Inhibition of PKB with triciribine, in the presence of isoproterenol, converted the activation of the βAR from stimulatory to inhibitory with regards to RNA synthesis, while ERK1/2, JNK and p38 inhibition reduced both basal and isoproterenol-stimulated activity. Analysis by qPCR indicated an increase in the expression of 18 S rRNA following isoproterenol treatment and a decrease in NFκB mRNA. Further qPCR experiments revealed that isoproterenol treatment also reduced the expression of several other genes involved in the activation of NFκB, while ERK1/2 and PKB inhibition substantially reversed this effect. Our results suggest that GPCRs on the nuclear membrane regulate nuclear functions such as gene expression and this process is modulated by activation/inhibition of downstream protein kinases within the nucleus.
Keywords
PTXTCAHRPERKCaMKIIPMSFpKaGPCRET-1PI3KPKBUTPnuclear factor kappa-light-chain-enhancer of activated B-cellsβARRNAPTX-100phenylmethanesulphonylfluorideJnkDTTqPCRPBSc-Jun N-terminal kinaseCa2+/calmodulin-dependent protein kinase IIDNAG protein-coupled receptor (GPCR)MAPKNFκBAdenosine TriphosphateATPadenylyl cyclaseRNA polymerasedeoxyribonucleic acidtrichloroacetic acidRNAribonucleic acidendothelin 1ISOisoproterenolTriton X-100dithiothreitolTranscriptionpertussis toxinNuclear membranePhosphate buffered salinephosphoinositide 3-kinaseSignal transductionquantitative real-time polymerase chain reactionHorseradish peroxideProtein kinaseprotein kinase Aprotein kinase Bmitogen activated protein kinaseextracellular signal-regulated kinaseβ-Adrenergic receptorEndothelin receptorbeta-adrenergic receptorG protein-coupled receptor
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Authors
George Vaniotis, Danny Del Duca, Phan Trieu, Charles V. Rohlicek, Terence E. Hébert, Bruce G. Allen,