University of Oulu

Mechanisms of cardiac chamber-specific gene expression of natriuretic peptides

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Author: Majalahti, Theresa1
Organizations: 1University of Oulu, Faculty of Medicine, Institute of Biomedicine, Department of Physiology
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: 2008
Publish Date: 2008-10-07
Thesis type: Doctoral Dissertation
Defence Note: Academic dissertation to be presented, with the assent of the Faculty of Medicine of the University of Oulu, for public defence in Auditorium F101 of the Department of Physiology (Aapistie 7), on October 17th, 2008, at 12 noon
Reviewer: Docent Mika Laine
Professor Matti Poutanen


Clarification of the mechanisms of cardiac-specific gene expression provides not only basic knowledge about how the gene expression is regulated in the heart, but also about the changes in the gene expression during the development of cardiovascular diseases. The purpose of this study was to analyze the mechanisms of cardiac chamber-specific gene expression and cardiac gene activation induced by mechanical load.

In the present study, the experiments were carried out by using two cardiac genes, salmon cardiac peptide (sCP) and rat B-type natriuretic peptide (BNP) genes as models. sCP was discovered previously in our laboratory and turned out to be extremely cardiac-specific, representing A-type natriuretic peptide characters in an exaggerated way. In neonatal rat cardiomyocytes, the sCP promoter activity was shown to be strictly restricted to atrial cells and the promoter to be inert to cardiac hypertrophy-inducing factors. In order to find out the mechanisms of earlier proved BNP gene activation by mechanical load, BNP promoter activity was studied in vivo in adult rat hearts. The tandem GATA transcription factor binding site at position -80/-91 was shown to be essential for the BNP gene induction by angiotensin II. To clarify the possiblity to transfer the characters of the BNP gene into the sCP gene, short BNP fragments were inserted to the sCP gene promoter. The otherwise atrial-restricted sCP promoter was shown to be switched on in rat ventricular cardiomyocytes by adding a short BNP proximal promoter element to the sCP promoter, preferably near to the transcription start site. This activity was partly dependent on the -80/-91 GATA sites in the BNP promoter. Thus, A-type natriuretic peptide regulation can be switched to B-type regulation by a short proximal BNP promoter element. In conclusion, these studies reveal certain basic differences in cardiac atrial and ventricular gene expression.

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Series: Acta Universitatis Ouluensis. D, Medica
ISSN-E: 1796-2234
ISBN: 978-951-42-8900-2
ISBN Print: 978-951-42-8899-9
Issue: 987
Copyright information: © University of Oulu, 2008. This publication is copyrighted. You may download, display and print it for your own personal use. Commercial use is prohibited.