2005 Fiscal Year Final Research Report Summary
Function of DNA mismatch repair system in the signal transduction of DNA damage response
| Project/Area Number |
16390122
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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 |
Experimental pathology
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| Research Institution | TOHOKU UNIVERSITY (2005)
Miyagi Cancer Center Research Institute (2004) |
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Principal Investigator |
SHIMODAIRA Hideki TOHOKU UNIVERSITY HOSPITAL, RESEARCH ASSOCIATE, 病院, 助手 (70373214)
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| Project Period (FY) |
2004 – 2005
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| Keywords | DNA mismatch repair / DNA damage / Drug response / Apoptosis |
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| Research Abstract |
DNA mismatch repair system has been known to keep genome integrity by correcting replication errors also induce apoptosis after DNA damage. We have already reported that mismatch repair protein PMS2 interact with pro-apoptotic protein p73 to cooperate in the induction of apoptotic reaction. In this study, we investigate how MLH1 associate with PMS2 and p73 complex in this system. First, we found that MLH1-PMS2 complex and PMS2-p73 complex existed separately in the cell extracts. The ternary complex of MLH1-PMS2-p73 was never detected. Second, we identified the binding domain of PMS2 with p73 as residue 500-707, which is partially overlapped with the MLH1-binding domain. Therefore, we speculate that MLH1-PMS2 complex function in the mismatch repair system but not in the apoptotic pathway. Our data also indicated that MLH1 mutations influence the PMS2-p73 complex formation. In particular, the mutations in the ATP binding domain of MLH1 inaease PMS2-p73 formation than wild-type MLH1. This raised the possibility that ATP binding will regulate MLH1-PMS2 or PMS2-p73 complex formation. Farther biochemical analyses are required for the interpretation about this phenomenon. To understand association between carcinogenesis in HNPCC and deficiency of the mismatch repair function or apoptotic induction, we firstly examined mismatch repair function of 101 MLH1 variants in yeast assays and an in vitro MMR assay. The majority of functionally inactive variants were located around the putative ATP binding pocket of the N-terminal domain or the whole region of the C-terminal domain. We also analyzed the distribution of loss-of-function variants on the secondary MLH1 structure or the crystal structure, to predict the pathogenicity of the MLH1 variants and to get the structural basis of loss-of-function. We are planning to asses these MLH1 variants in terms of the ability of apoptotic induction.
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