| Co-Investigator(Kenkyū-buntansha) |
NISHIO Hisahide Kobe University, Graduate School of Medicine, Professor, 医学系研究科, 教授 (80189258)
AYAKI Hitoshi Kobe University, Graduate School of Medicine, Associate Professor, 医学系研究科, 助教授 (80222701)
西本 啓介 神戸大学, 大学院・医学系研究科, 助手 (00362773)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
We investigated divalent metal ions which were supposed to affect splicing reaction, especially focused on the carcinogenic metal cadmium (Cd). We also explored the differential expression of the genes including spliceosomal proteins affected by Cd(II) exposure.
1.Cd restored splicing reaction inhibited by Zn depletion.
Zn-depletion in the in vitro splicing reaction inhibited the second step of splicing. The addition of Cd(II) at 1, 5, and 10μM to the reaction restored the splicing activity to 2, 24 and 72% of the control, while higher concentrations of Cd(II) decreased the splicing activity. Hg(II) slightly restored the splicing activity to 4% of the control value, but Co(II), Cu(II), Mg(II) and Mn(II) did not show any restoration. These results suggest that Cd(II) has a bifunctional property regarding RNA splicing, and is stimulatory at low concentrations and inhibitory at high concentrations.
2.Cd induced mRNA of spliceosomal proteins.
We investigated the mRNA expression level of several spliceosomal proteins after Cd(II) exposure. By 10μM of Cd(II) exposure, SF1 mRNA was induced 2.7 folds at 16h, and ZNF265 showed 4 folds induction at 9h. As ZNF265 was reported to regulate the alternative splicing of Tra-β1 in a concentration dependent manner, it seems possible that the induction of ZN265 by Cd(II)exposure may affect the splicing mechanisms for some genes.
3.Cd induced several genes including homeobox genes.
We have identified several differentially expressed genes by Differential Display. The genes included HOXA7, HOXA9, HOX8,CHIC2, JunB and TBC1D14. The homeobox genes were reported to be increased in some kinds of cancers. In this study, HOX8 was increased to 13.5 folds of the control value by Cd(II) exposure, while HOXA7 and HOXA9 were decreased to 0.26 and 0.2 fold, respectively. CHIC2 and JunB were induced 8.8 and 7.0 folds, respectively, and TBC1D14 was decreased to 0.3 fold.
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