title: Prorenin induces intracellular signaling in cardiomyocytes independently of angiotensin II.
abstract: Tissue accumulation of circulating prorenin results in angiotensin generation, but could also, through binding to the recently cloned (pro)renin receptor, lead to angiotensin-independent effects, like p42/p44 mitogen-activated protein kinase (MAPK) activation and plasminogen-activator inhibitor (PAI)-1 release. Here we investigated whether prorenin exerts angiotensin-independent effects in neonatal rat cardiomyocytes. Polyclonal antibodies detected the (pro)renin receptor in these cells. Prorenin affected neither p42/p44 MAPK nor PAI-1. PAI-1 release did occur during coincubation with angiotensinogen, suggesting that this effect is angiotensin mediated. Prorenin concentration-dependently activated p38 MAPK and simultaneously phosphorylated HSP27. The latter phosphorylation was blocked by the p38 MAPK inhibitor SB203580. Rat microarray gene (n=4800) transcription profiling of myocytes stimulated with prorenin detected 260 regulated genes (P<0.001 versus control), among which genes downstream of p38 MAPK and HSP27 involved in actin filament dynamics and (cis-)regulated genes confined in blood pressure and diabetes QTL regions, like Syntaxin-7, were overrepresented. Quantitative real-time RT-PCR of 7 selected genes (Opg, Timp1, Best5, Hsp27, pro-Anp, Col3a1, and Hk2) revealed temporal regulation, with peak levels occurring after 4 hours of prorenin exposure. This regulation was not altered in the presence of the renin inhibitor aliskiren or the angiotensin II type 1 receptor antagonist eprosartan. Finally, pilot 2D proteomic differential display experiments revealed actin cytoskeleton changes in cardiomyocytes after 48 hours of prorenin stimulation. In conclusion, prorenin exerts angiotensin-independent effects in cardiomyocytes. Prorenin-induced stimulation of the p38 MAPK/HSP27 pathway, resulting in alterations in actin filament dynamics, may underlie the severe cardiac hypertrophy that has been described previously in rats with hepatic prorenin overexpression.
authors.affiliation: Department of Pharmacology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Jasper J
authors.initials: JJ
authors.lastname: Saris
authors.forename: Peter A C
authors.initials: PA
authors.lastname: 't Hoen
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Garrelds
authors.forename: Dick H W
authors.initials: DH
authors.lastname: Dekkers
authors.forename: Johan T
authors.initials: JT
authors.lastname: den Dunnen
authors.forename: Jos M J
authors.initials: JM
authors.lastname: Lamers
authors.forename: A H
authors.initials: AH
authors.lastname: Jan Danser
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D012085:Chymosin; D004789:Enzyme Activation; D004792:Enzyme Precursors; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D012083:Renin / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D004792:Enzyme Precursors; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D017395:Plasminogen Activator Inhibitor 1; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D000804:Angiotensin II; D020928:Mitogen-Activated Protein Kinases; C032443:prorennin; D012083:Renin; D012085:Chymosin