1998 Fiscal Year Final Research Report Summary
Analyses of transcriptional regulation and signal transduction of sarcoplasmic reticulum Ca^<2+>
| Project/Area Number |
09670692
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Gunma University School of Medicine |
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Principal Investigator |
ARAI Masashi Gunma University, Second Department of Internal Medicine, Research Fellow, 医学部, 助手 (60270857)
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| Project Period (FY) |
1997 – 1998
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| Keywords | SERCA2 / doxorubicin / heart failure / reactive oxygen / Egr-1 / MAPK / gene transcription |
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| Research Abstract |
Impaired Ca2+ handling in sarcoplasmic reticulum is a central mechanism that accounts for the cardiac dysfunction seen in doxorubicin induced-cardiomyopathy. We have recently demonstrated that mRNA expression for sarcoplasmic reticulum Ca2+-ATPase (SERCA2), the major Ca2+ transport protein in sarcoplasmic reticulum, is markedly decreased in doxorubicin induced-failing hearts.
The purpose of this study was to clarify the molecular mechanisms by which doxorubicin down-regulates SBRCA2 gene. N-acetylcysteine ; an anti-oxidant, protected SERCA2 mRNA levels from a decrease induced by doxorubicin in cultured rat cardiac myocytes, and the concentration of hydrogen peroxide was 3-fold higher than basal level, suggesting that hydrogen peroxidels an intracellular mediator of doxorubicin. Luciferase reporter assay revealed that 5' flanking sequence from -284 to -72 bp of SERCA2 gene has a doxorubicin responsible element. Of the transcription factors that have putative binding motifs in the 5' flanking -284 to -72 bp region of SERCA2 gene, the expression of Egr-1 mRNA was markedly increased after doxorubicin administration. Over-expression of Egr-1 significantly diminished the transcription of SERCA2 gene. Additionally, antisense oligonucleotides against Egr-1 rescued the doxorubicin induced-decrease of SERCA2 mRNA expression. These results suggest that Egr-1 is a transcriptional inhibitor of SERCA2 gene under doxorubicin administration. Finally, we clarified kinases which controls Egr-1 and, thus SERCA2 genes. Three MAP kinases ; p44/42 MAP kinase, p38 MAP kinase and SAPK/JNK were all activated by doxorubicin. PD98059, a specific blocker of p44/42 MAP kinase kinase, had a preventive effect on the doxorubicin induced-increase of Egr- 1 gene and the decrease of SERCA2 gene.
Our studies indicate that reactive oxygen intermediates, transcription factor Egr-1 and p44/42 MAP kinase have a pivotal role for the transcriptional regulation of SERCA2 gene in doxorubicin signaling pathway.
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[Publications] Ohyama Y,Kurabayashi M,Masuda H,Nakamura T,Aihara Y,Kaname T,Arai M,Aizawa H,Matsumura Y,Kuro-o M,Nabeshima Y,Nagai R.: "Molecular cloning of rat klotho cDNA : Markedly decreased expression of klotho by acute inflammatory stress" Biochem Biophys Res Commun. 251. 920-825 (1998)
Description
「研究成果報告書概要(欧文)」より
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