Role of p90 ribosomal S6 kinase-mediated prorenin-converting enzyme in ischemic and diabetic myocardium

Seigo Itoh, Bo Ding, Tetsuro Shishido, Nicole Lerner-Marmarosh, Nadan Wang, Naoya Maekawa, Bradford C. Berk, Yasuchika Takeishi, Chen Yan, Burns C. Blaxall, Jun Ichi Abe

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

BACKGROUND - Epidemiological data strongly indicate that diabetes increases the incidence of heart failure. Although the benefit of angiotensin-converting enzyme inhibitor (ACE-I) treatment during and after myocardial infarction has been found to be greater in diabetics than nondiabetics and activation of the renin-angiotensin system (RAS) has been implicated, the molecular basis of these actions remains unclear. METHODS AND RESULTS - We generated transgenic mice with cardiac-specific overexpression of wild-type p90 ribosomal S6 kinase (WT-p90RSK-Tg) and a dominant-negative form of p90RSK (DN-p90RSK-Tg). Recovery of cardiac function after ischemia/reperfusion in WT-p90RSK-Tg isolated mouse hearts was significantly impaired. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed specific induction of prorenin-converting enzyme (PRECE) in WT-p90RSK-Tg mice. mRNA induction of PRECE was confirmed with serial angiotensinogen protein reduction after perfusion in WT-p90RSK-Tg mice, suggesting an increase of angiotensinogen cleavage and subsequent RAS activation in WT-p90RSK-Tg mice. We investigated the role of the RAS in WT-p90RSK-Tg animals after ischemia/reperfusion with the use of an ACE-I (captopril) and an angiotensin II type 1 receptor blocker (olmesartan). We did not observe any effect of these inhibitors in non-Tg littermate controls, thus corroborating other reports in rodents. In contrast, both captopril and olmesartan significantly improved cardiac function and reduced infarct size in WT-p90RSK-Tg mice. At 8 months of age, WT-p90RSK-Tg mice developed cardiac dysfunction. p90RSK activity and PRECE mRNA were both increased by streptozotocin-induced hyperglycemia in non-Tg littermate controls, whereas DN-p90RSK-Tg animals exposed to streptozotocin did not have PRECE induction. CONCLUSIONS - This study demonstrates the critical role of p90RSK in hyperglycemia-mediated myocardial PRECE induction, which may explain the augmentation of the RAS in diabetic hearts and provide an alternative therapeutic approach to treat diabetic cardiomyopathy.

Original languageEnglish (US)
Pages (from-to)1787-1798
Number of pages12
JournalCirculation
Volume113
Issue number14
DOIs
StatePublished - Apr 2006
Externally publishedYes

Keywords

  • Angiotensin
  • Diabetes mellitus
  • Ischemia
  • Renin
  • Signal transduction

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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