1994 Fiscal Year Final Research Report Summary
Metabolism of calcium and regulation of gene expression
| Project/Area Number |
05670848
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
内分泌・代謝学
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
IGARASHI Tetsuya 4th.Dept.of Internal Med., Univ.of Tokyo, Associate Professor, 医学部(分), 助教授 (00134601)
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| Co-Investigator(Kenkyū-buntansha) |
OKAZAKI Tomoki The Health Service Center, University of Tokyo, Assistant Professor, 保健センター, 講師 (60203973)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Parathyroid hormone / Calcium / Regulation of gene expression / Transcription factor / Calcium receptor |
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| Research Abstract |
By using the negative calcium-responsive element (nCaRE) which is found in the human PTH gene and required for calcium-dependent suppression of the gene's transcription, we could detect the cellular nuclear factor, nCaRE-binding protein (nCaREB). The binding activity of this factor to the DNA element is dependent on the extracellular concentration of calcium. The DNA binding is followed by suppression of transcription of the gene attached to nCaRE.nCaREB seems to consist of at least two subcomponents, one of which turned out to be redox factor 1 (ref1), a nuclear protein. Its expression over the wide variety of cells and tissues matches well the fact that specific binding of nCaREB to the element can be detected in almost all the cell lines ever tested. The amounts of ref-1 protein and mRNA coding for it increase when extracellular calcium concentration rises. This observation is also supported by the experiment in which addition of cycloheximide to the cells blocks enhancement of the binding activity of nCaREB to nCaRE by an increase in the extracellular calcium concentration. Ref1 is an endonuclease involved in the DNA repair process and known to enhance DNA-binding activity of various nuclear transcription factors by altering the redox state of those proteins. A series of experiments has shown that (1) specific binding activity of nCaREB to nCaRE is decreased by anti-ref1 antibody, (2) introduction of antisense DNA of ref1 mRNA induces disappearance of calcium-dependent suppression of transcription mediated by nCaRE.It is, thus, deduced that ref1 functions as a DNA-binding subcomponent of nCaREB and induces transcriptional repression. We have already cloned the candidate for another subcomponent of nCaREB and have been studying the relationship between ref1.
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