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Homocysteine-induced cardiomyocyte apoptosis and plasma membrane flip-flop are independent of S-adenosylhomocysteine: a crucial role for nuclear p47(phox).
MedLine Citation:
PMID:  21739151     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
We previously found that homocysteine (Hcy) induced plasma membrane flip-flop, apoptosis, and necrosis in cardiomyocytes. Inactivation of flippase by Hcy induced membrane flip-flop, while apoptosis was induced via a NOX2-dependent mechanism. It has been suggested that S-adenosylhomocysteine (SAH) is the main causative factor in hyperhomocysteinemia (HHC)-induced pathogenesis of cardiovascular disease. Therefore, we evaluated whether the observed cytotoxic effect of Hcy in cardiomyocytes is SAH dependent. Rat cardiomyoblasts (H9c2 cells) were treated under different conditions: (1) non-treated control (1.5 nM intracellular SAH with 2.8 μM extracellular L: -Hcy), (2) incubation with 50 μM adenosine-2,3-dialdehyde (ADA resulting in 83.5 nM intracellular SAH, and 1.6 μM extracellular L: -Hcy), (3) incubation with 2.5 mM D: ,L: -Hcy (resulting in 68 nM intracellular SAH and 1513 μM extracellular L: -Hcy) with or without 10 μM reactive oxygen species (ROS)-inhibitor apocynin, and (4) incubation with 100 nM, 10 μM, and 100 μM SAH. We then determined the effect on annexin V/propodium iodide positivity, flippase activity, caspase-3 activity, intracellular NOX2 and p47(phox) expression and localization, and nuclear ROS production. In contrast to Hcy, ADA did not induce apoptosis, necrosis, or membrane flip-flop. Remarkably, both ADA and Hcy induced a significant increase in nuclear NOX2 expression. However, in contrast to ADA, Hcy additionally induced nuclear p47(phox) expression, increased nuclear ROS production, and inactivated flippase. Incubation with SAH did not have an effect on cell viability, nor on flippase activity, nor on nuclear NOX2-, p47phox expression or nuclear ROS production. HHC-induced membrane flip-flop and apoptosis in cardiomyocytes is due to increased Hcy levels and not primarily related to increased intracellular SAH, which plays a crucial role in nuclear p47(phox) translocation and subsequent ROS production.
Authors:
Jessica A Sipkens; Paul A J Krijnen; Nynke E Hahn; Melissa Wassink; Christof Meischl; Desirée E C Smith; René J P Musters; Coen D A Stehouwer; Jan A Rauwerda; Victor W M van Hinsbergh; Hans W M Niessen
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-7-8
Journal Detail:
Title:  Molecular and cellular biochemistry     Volume:  -     ISSN:  1573-4919     ISO Abbreviation:  -     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-7-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0364456     Medline TA:  Mol Cell Biochem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Pathology, VU University Medical Center, Room nr. 0E46, De Boelelaan 1117, 1007 MB, Amsterdam, The Netherlands.
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