Dataset Information

S1P3-mediated cardiac fibrosis in sphingosine kinase 1 transgenic mice involves reactive oxygen species.

ABSTRACT:

Aims

Sphingosine kinase 1 (SPHK1), its product sphingosine-1-phosphate (S1P), and S1P receptor subtypes have been suggested to play protective roles for cardiomyocytes in animal models of ischaemic preconditioning and cardiac ischaemia/reperfusion injury. To get more insight into roles for SPHK1 in vivo, we have generated SPHK1-transgenic (TG) mice and analysed the cardiac phenotype.

Methods and results

SPHK1-TG mice overexpressed SPHK1 in diverse tissues, with a nearly 20-fold increase in enzymatic activity. The TG mice grew normally with normal blood chemistry, cell counts, heart rate, and blood pressure. Unexpectedly, TG mice with high but not low expression levels of SPHK1 developed progressive myocardial degeneration and fibrosis, with upregulation of embryonic genes, elevated RhoA and Rac1 activity, stimulation of Smad3 phosphorylation, and increased levels of oxidative stress markers. Treatment of juvenile TG mice with pitavastatin, an established inhibitor of the Rho family G proteins, or deletion of S1P3, a major myocardial S1P receptor subtype that couples to Rho GTPases and transactivates Smad signalling, both inhibited cardiac fibrosis with concomitant inhibition of SPHK1-dependent Smad-3 phosphorylation. In addition, the anti-oxidant N-2-mercaptopropyonylglycine, which reduces reactive oxygen species (ROS), also inhibited cardiac fibrosis. In in vivo ischaemia/reperfusion injury, the size of myocardial infarct was 30% decreased in SPHK1-TG mice compared with wild-type mice.

Conclusion

These results suggest that chronic activation of SPHK1-S1P signalling results in both pathological cardiac remodelling through ROS mediated by S1P3 and favourable cardioprotective effects.

SUBMITTER: Takuwa N

PROVIDER: S-EPMC2802201 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Publications

S1P3-mediated cardiac fibrosis in sphingosine kinase 1 transgenic mice involves reactive oxygen species.

Takuwa Noriko N Ohkura Sei-Ichiro S Takashima Shin-Ichiro S Ohtani Keisuke K Okamoto Yasuo Y Tanaka Tamotsu T Hirano Kaoru K Usui Soichiro S Wang Fei F Du Wa W Yoshioka Kazuaki K Banno Yoshiko Y Sasaki Motoko M Ichi Ikuyo I Okamura Miwa M Sugimoto Naotoshi N Mizugishi Kiyomi K Nakanuma Yasuni Y Ishii Isao I Takamura Masayuki M Kaneko Shuichi S Kojo Shosuke S Satouchi Kiyoshi K Mitumori Kunitoshi K Chun Jerold J Takuwa Yoh Y

Cardiovascular research 20090915 3

<h4>Aims</h4>Sphingosine kinase 1 (SPHK1), its product sphingosine-1-phosphate (S1P), and S1P receptor subtypes have been suggested to play protective roles for cardiomyocytes in animal models of ischaemic preconditioning and cardiac ischaemia/reperfusion injury. To get more insight into roles for SPHK1 in vivo, we have generated SPHK1-transgenic (TG) mice and analysed the cardiac phenotype.<h4>Methods and results</h4>SPHK1-TG mice overexpressed SPHK1 in diverse tissues, with a nearly 20-fold in ...[more]

PMID: 19755413

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Project description:Na(V)1.5 is a cardiac voltage-gated Na(+) channel ?subunit and is encoded by the SCN5a gene. The activity of this channel determines cardiac depolarization and electrical conduction. Channel defects, including mutations and decrease of channel protein levels, have been linked to the development of cardiac arrhythmias. The molecular mechanisms underlying the regulation of Na(V)1.5 expression are largely unknown. Forkhead box O (Foxo) proteins are transcriptional factors that bind the consensus DNA sequences in their target gene promoters and regulate the expression of these genes. Comparative analysis revealed conserved DNA sequences, 5'-CAAAACA-3' (insulin responsive element, IRE), in rat, mouse and human SCN5a promoters with the latter two containing two overlapping Foxo protein binding IREs, 5'-CAAAACAAAACA-3'. This finding led us to hypothesize that Foxo1 regulates Na(V)1.5 expression by directly binding the SCN5a promoter and affecting its transcriptional activity. In the present study, we determined whether Foxo1 regulates Na(V)1.5 expression at the transcriptional level and also defined the role of Foxo1 in hydrogen peroxide (H(2)O(2))-mediated Na(V)1.5 suppression in HL-1 cardiomyocytes using chromatin immunoprecipitation (ChIP), constitutively nuclear Foxo1 expression, and RNAi Foxo1 knockdown as well as whole cell voltage-clamp recordings. ChIP with anti-Foxo1 antibody and follow-up semi-quantitative PCR with primers flanking Foxo1 binding sites in the proximal SCN5a promoter region clearly demonstrated enrichment of DNA, confirming Foxo1 recruitment to this consensus sequence. Foxo1 mutant (T24A/S319A-GFP, Foxo1-AA-GFP) was retained in nuclei, leading to a decrease of Na(V)1.5 expression and Na(+) current, while silencing of Foxo1 expression by RNAi resulted in the augmentation of Na(V)1.5 expression. H(2)O(2) significantly reduced Na(V)1.5 expression by promoting Foxo1 nuclear localization and this reduction was prevented by RNAi silencing Foxo1 expression. These studies indicate that Foxo1 negatively regulates Na(V)1.5 expression in cardiomyocytes and reactive oxygen species suppress Na(V)1.5 expression through Foxo1.

Dataset Information

S1P3-mediated cardiac fibrosis in sphingosine kinase 1 transgenic mice involves reactive oxygen species.

Aims

Methods and results

Conclusion

Publications

S1P3-mediated cardiac fibrosis in sphingosine kinase 1 transgenic mice involves reactive oxygen species.

Similar Datasets

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