2005 Fiscal Year Final Research Report Summary
Telomere maintenance by chromosome damage response mechanism
| Project/Area Number |
16570145
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Molecular biology
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
NABETANI Akira Kyoto University, Graduate School of Biostudies, Instructor, 大学院・生命科学研究科, 助手 (40334495)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ISHIKAWA Fuyuki Kyoto University, Graduate School of Biostudies, Professor, 大学院・生命科学研究科, 教授 (30184493)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | Telomere / Damage checkpoint / Recombination / Chromosome |
|---|
| Research Abstract |
We analyzed the role of the damage checkpoint mechanism in the telomere maintenance mechanism of the ALT cells, which are independent from telomerase. At first, we found that checkpoint Rad protein group (the Rad9-Hus1-Rad1 clamp complex and the Rad17-RFC loader complex) were colocalized with telomeric DNA to form the ALT-associated PML body (APB) in the cell nucleus. On the other hand, phosphorylated Rad17 and γ-H2AX, markers for DNA damage, were also localized at a part of APB. This result suggests that the damage response of the ALT cell telomere could be divided into two stages : the localization of checkpoint Rad protein and the activation of ATM/ATR kinases. Incorporation of BrdU at a part of APB was observed and this is sensitive to caffeine, an inhibitor to ATM/ATR. This suggests that the activation of the damage response mechanism be indispensable to the telomere reproduction by the ALT cell. We next examined a structural feature of telomere DNA of ALT cells, to clarify why the damage response is activated. From Southern hybridization analyses, we found the single-stranded DNA structure of the telomere DNA specifically in ALT cells. This suggests that the damaged telomeric DNA, such as nick and gap, exists in ALT cell, and this structure could be maintained. We hypothesized that the stall of the replication fork at telomere might induce recombination and this would be the mechanism for the lengthening of telomere in the ALT cells.
|
