Journal
INFLAMMATION
Volume 31, Issue 3, Pages 180-188Publisher
SPRINGER/PLENUM PUBLISHERS
DOI: 10.1007/s10753-008-9063-5
Keywords
tumor necrosis factor; apoptosis; cardiomyocyte; signal transduction
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Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine involved in mitogen-activated protein kinase (MAPK) signaling pathways, contributes to the pathogenesis of cardiovascular diseases. Recently, suppressor of cytokine signaling-1 (SOCS-1) has been shown to modulate responses to TNF-a. However, whether SOCS-I suppresses TNF-alpha-dependent apoptotic processes in cardiomyocytes and whether MAPK pathways mediate this effect have not been clearly elucidated. This study was carried out to define the role of SOCS-I on TNF-alpha-induced apoptosis in neonatal rat cardiomyocytes and to investigate the signal pathways involved. Exposure to TNF-alpha (10 ng/ml for 24 h) significantly increased the number of apoptotic cells, the activity of caspase-8 and caspase-3, and the Bax/Bcl-xl ratio. In contrast, adenovirus-mediated gene transfer of SOCS-1 reversed the pro-apoptotic effect of TNF-alpha. Additionally, preincubation of cardiomyocytes with the extracellular signal-regulated kinase-1 and -2 (ERK1/2) inhibitor PD98059 attenuated the protective effect of SOCS-1, but the p38-MAPK inhibitor SB203580 and the c-Jun amino-terminal kinase (JNK) inhibitor SP600125 had no effect. Furthermore, the TNF-alpha-induced decrease in the phosphorylation of ERK1/2 was abolished by overexpression of SOCS-1. These findings suggest that SOCS-I prevents TNF-alpha-induced apoptosis in cardiac myocytes via ERK1/2 pathway activation.
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