2001 Fiscal Year Final Research Report Summary
Abnormal morphology of the testes of the fyn-deficient mice and analysis of the function of Fyn tyrosine kinase
| Project/Area Number |
12670007
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General anatomy (including Histology/Embryology)
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| Research Institution | CHIBA UNIVERSITY |
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Principal Investigator |
MAEKAWA Mamiko Chiba University, Graduate School of Medicine, Assistant, 大学院・医学研究院, 助手 (20181571)
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| Co-Investigator(Kenkyū-buntansha) |
TOYAMA Yoshiro Chiba University, Graduate School of Medicine, Lecturer, 大学院・医学研究院, 講師 (70009637)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Fyn / tyrosine kinase / testis / Sertoli cell / spermatogenesis / knockout mouse |
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| Research Abstract |
1. Significant reduction of the testis weight and degenerated germ cells were found at the age of 3 and 4 weeks of fyn-deficient mice. Electron microscopy revealed that fyn-deficient testis showed ultrastructural abnormality in specialized junctional structures of the Sertoli cells, termed the ectoplasmic specializations (ES). Small unusual vesicles were found in the actin filament layer of the ES. Immunohistochemical studies demonstrated that Fyn was concentrated together with actin filaments at the ES. At these sites high level of phosphotyrosine was also immunostained in the wild type testes, while phosphotyrosine immunoreactivity was decreased in the fyn -deficient testes. These findings suggest that Fyn kinase functions at the ectoplasmic specializations of the Sertoli cells in the testis.
2. Immunoblot analyzes revealed that Fyn was distributed mostly in the Triton X-100 insoluble cytoskeletal fraction prepared from the wild-type mouse testis, suggesting that Fyn may be associated with cytoskeletal proteins such as actin filaments. A tyrosine phophorylated protein at around 80 kDa (P80) was prominent in the Triton-insoluble fraction from wild-type testis. However, P80 was specifically decreased in the fyn-deficient testes. This finding indicated that P80 might be the target of Fyn kinase, and that P80 may play a role in a Fyn-mediated signal transduction in the mouse testis.
3. We found that a mouse Sertoli cell line, TM4, expressed Fyn protein. Tyrosine-phosphorylated proteins were examined in the TM4 cell extracts by two-dimensional immunoblot analysis. When the cells was treated with environmental endocrine disrupters, such as diethylstilbestrol, the level of tyrosine phosphorylation of one protein at approximately 38kDa (P38) was conspicuously increased compared to the control cells. It is possible that Fyn tyrosine kinase may be involved in the phosphorylation of the P38.
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