title: p90 ribosomal S6 kinases play a significant role in early gene regulation in the cardiomyocyte response to G(q)-protein-coupled receptor stimuli, endothelin-1 and α(1)-adrenergic receptor agonists.
abstract: ERK1/2 (extracellular-signal-regulated kinase 1/2) and their substrates RSKs (p90 ribosomal S6 kinases) phosphorylate different transcription factors, contributing differentially to transcriptomic profiles. In cardiomyocytes ERK1/2 are required for >70% of the transcriptomic response to endothelin-1. In the present study we investigated the role of RSKs in the transcriptomic responses to the G(q)-protein-coupled receptor agonists endothelin-1, phenylephrine (a generic α(1)-adrenergic receptor agonist) and A61603 (α(1A)-adrenergic receptor selective). Phospho-ERK1/2 and phospho-RSKs appeared in cardiomyocyte nuclei within 2-3 min of stimulation (endothelin-1>A61603≈phenylephrine). All agonists increased nuclear RSK2, but only endothelin-1 increased the nuclear RSK1 content. PD184352 (inhibits ERK1/2 activation) and BI-D1870 (inhibits RSKs) were used to dissect the contribution of RSKs to the endothelin-1-responsive transcriptome. Of the 213 RNAs up-regulated after 1 h, 51% required RSKs for their up-regulation, whereas 29% required ERK1/2 but not RSKs. The transcriptomic response to phenylephrine overlapped with, but was not identical with, endothelin-1. As with endothelin-1, PD184352 inhibited the up-regulation of most phenylephrine-responsive transcripts, but the greater variation in the effects of BI-D1870 suggests that differential RSK signalling influences global gene expression. A61603 induced similar changes in RNA expression in cardiomyocytes as phenylephrine, indicating that the signal was mediated largely through α(1A)-adrenergic receptors. A61603 also increased expression of immediate early genes in perfused adult rat hearts and, as in cardiomyocytes, up-regulation of the majority of genes was inhibited by PD184352. PD184352 or BI-D1870 prevented the increased surface area induced by endothelin-1 in cardiomyocytes. Thus RSKs play a significant role in regulating cardiomyocyte gene expression and hypertrophy in response to G(q)-protein-coupled receptor stimulation.
authors.affiliation: School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6BX, UK.
authors.forename: Emre
authors.initials: E
authors.lastname: Amirak
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Fuller
authors.forename: Peter H
authors.initials: PH
authors.lastname: Sugden
authors.forename: Angela
authors.initials: A
authors.lastname: Clerk
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A / Q000819:agonists* / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C120227:2-(2-chloro-4-iodophenylamino)-N-cyclopropylmethoxy-3,4-difluorobenzamide; D000316:Adrenergic alpha-Agonists; D001549:Benzamides; D044022:Receptor, Endothelin A; D018340:Receptors, Adrenergic, alpha-1; D012313:RNA; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048052:Mitogen-Activated Protein Kinase 3