2005 Fiscal Year Final Research Report Summary
Dynamism of epigenetic regulation of expression of the rice SINE, p-SINE1.
| Project/Area Number |
16570001
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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 |
Genetics/Genome dynamics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TSUCHIMOTO Suguru The University of Tokyo, Institution of Molecular and Cellular Biosciences, Research associate, 分子細胞生物学研究所, 助手 (60212057)
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| Project Period (FY) |
2004 – 2005
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| Keywords | rice / SINE / retroposon / transposon / epigenetic / methylation / siRNA |
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| Research Abstract |
To know the methylation status of various p-SINE1 sequences, we performed bisulfite genomic sequencing method to examine cytosine methylation of the p-SINE1 sequence and the flanking sequence of the eight selected p-SINE1 members using genomic DNA from rice cultured cells or the plant tissue. The results showed that cytosine residues in the p-SINE1 sequences of all the examined members were more heavily methylated than those in the flanking sequences. The p-SINE1 expression level increased by the treatment of cultured cells with the inhibitor of DNA methyltransferase, but the methylation level did not decrease significantly. Instead, we found that the amount of siRNA with the homologous sequence to p-SINE1 (p-SINE1 siRNA) decreased by the inhibitor treatment. To examine the involvement of siRNA in repression of the p-SINE1 expression and methylation of the p-SINE1 sequence, we used five transgenic cell lines in which each of five rice DCL(Dicer-Like) genes (OsDCL1〜OsDCL5) encoding RNas
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e proteins which are involved in the siRNA production. We then found that (1) the p-SINE1 siRNA level especially reduced in OsDCL3 and OsDCL5 suppression lines, (2) the expression level of p-SINE1 especially increased in OsDCL3 and OsDCL5 suppression lines, and (3) DNA methylation level of p-SINE1 members did not reduce significantly in OsDCL3 and OsDCL5 suppression lines, but reduced most remarkably in an OsDCL4 suppression line. These show that siRNA produced by OsDCL3 and OsDCL5 is involved in repression of the p-SINE1 expression, but is not required for DNA methylation of some p-SINE1 sequences. We examined the p-SINE1 siRNA level in several rice tissues, and found that the siRNA level was high in tissues with the high p-SINE1 expression. The siRNA level did not change after the heat treatment of cells, although the p-SINE1 expression rapidly reduced. All these results suggest that the p-SINE1 siRNA is not involved in the tissue-specific regulation of the p-SINE1 expression or reduction of the expression level by the environmental stress, but is rather involved in the constitutive repression. Less
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Research Products
(4 results)
