1998 Fiscal Year Final Research Report Summary
Study on Outsode-in Signal Transduction via Platelet Membrane Glycoprotein lb
| Project/Area Number |
09671143
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Hematology
|
|---|
| Research Institution | THE TOKYO METROPOLITAN INSTITUT OF MEDICAL SCIENCE |
|---|
Principal Investigator |
YAMAMOTO Naomasa Tokyo Metro.Institute of Med.Science, Researcher, 循環器病, 研究員 (50150884)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TANOUE Kenjiro Tokyo Metro.Institute of Med.Science, Researcher, 循環器病, 研究員 (30014137)
MATSUNO Kazuhiko Hokkaido University, Professor, 医療技術短期大学部, 教授 (70102332)
KASE Ryoichi Tokyo Metro.Institute of Med.Science, Researcher, 臨床遺伝, 研究員 (20150203)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | GPlbalpha / 14-3-3 / ATP-release / ristocetin-induced agglutination / GPlb / IX / V complex / BSS Tokyo / Signal trunsduction / Bernard-Soulier syndrome |
|---|
| Research Abstract |
GPIb/IX/V complex is a receptor for von Willebrand factor and thrombin and plays important roles in platelet adhesion and aggregation. Congenital abnormalities in the complex result in BSS with giant platelets, thrombocytopenia and sever bleeding disorder. We have found a mutation Q545 (CAA)-to-Stop (TAA) in the gene coding GPlbalpha of a patient with BSS.The patient is 23 years old female with diagnosis of BSS at the age of two because of absence of ristocetin-induced agglutination (Matsuno et al, 1976). In this study, flow cytometric analysis revealed the expression of GPlbalpha, GPIX and GPV.The patient's platelets showed 30% of normal agglutination at 2 min after addition of 1.2 mg/ml ristocetin which was completely dissociated at 10 min. Agglutination in response to 1.5 mg/ml ristocetin was 50% of normal agglutination that was partially dissociated. ATP-release was markedly impaired. A homozygous mutation Q545 (CAA)-to-Stop (TAA) in the cytoplasmic domain of GPlbalpha was identified by sequencing the PCR-amplified genomic DNA fragments covering full coding region of GPlbalpha. Truncated GPlbalpha was expressed on the surface and was formed a disulfide-bond with GPlbbeta while the truncated GPlbalpha in the cytosol did not form. Variable number of tandem repeats of the patient was C/C type. These results suggest that the nonsense mutation at Q545 in the cytoplasmic domain of GPlbalpha is responsible for BSS Tokyo II.The reversible ristocetin-induced agglutination of the platelets is possibly due to incomplete association of the truncated GPlbalpha with actin-binding protein which may disrupt reorganization of cytoskeletal proteins. In conclusion, C-terminal region of GPlbalpha starting from Q545 absent in BSS Tokyo II plays an important role in transducing GPlb-dependentoutside-in signal via reorganization of cytoskeletal proteins such as 14-3-3 and actin-binding protein.
|
