2005 Fiscal Year Final Research Report Summary
Clarification of the regulatory mechanism of glucocorticoid receptor function and its application to development of novel drugs
| Project/Area Number |
16390268
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Endocrinology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TANAKA HIROTOSHI the University of Tokyo, The Institute of Medical Science, Associate Professor, 医科学研究所, 助教授 (00171794)
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| Project Period (FY) |
2004 – 2005
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| Keywords | nuclear receptor / transcription / DNA / immunology / gene / molecular biology / endocrinology / inflammation |
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| Research Abstract |
We used the GR-specific phenylpyrazolosteroid cortivazol (CVZ) to probe the plasticity and functional modularity of the GR. Structural docking analysis revealed that the phenylpyrazole A-ring of CVZ establishes additional contacts with helices 3 and 5 of the LBD that may contribute to a more stable LBD configuration. Structural and functional analysis revealed that CVZ is able to compensate for the deleterious effects of a C-terminal deletion of the LBD in such a manner that mimics the stabilizing influence of the F602S point mutation. CVZ-mediated productive recruitment of TIF2 to the C-terminally deleted LBD requires the receptor's own DBD and is positively influenced by the N-terminal regions of GR or PR. These results support a model where ligand-dependent conformational changes in the LBD play a role in GR-mediated gene regulation via modular interaction with the DBD and AF-1.
HEXIM1 protein has been shown to form a protein-RNA complex composed of 7SK snRNA and positive transcription elongation factor b (P-TEFb) which is composed of cyclin-dependent kinase 9 (CDK9) and cyclin T1, and to inhibit the kinase activity of CDK9, thereby suppressing RNA polymerase II-dependent transcriptional elongation. Here, we biochemically demonstrated that HEXIM1 forms a distinct complex with glucocorticoid receptor (GR), without RNA, CDK9, or cyclin T1. HEXIM1, through its arginine-rich nuclear localization signal (NLS), directly associates with the ligand-binding domain of GR. Ectopic expression of HEXIM1 decreased ligand-dependent association between GR and TIF2. These results indicate that HEXIM1 has dual roles in transcriptional regulation : inhibition of transcriptional elongation dependent on 7SK RNA and P-TEFb and interference with the sequence-specific transcription factor GR via a direct protein-protein interaction.
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Research Products
(12 results)
