2006 Fiscal Year Final Research Report Summary
Novel function of pigment granules in the pigment cells of retina
| Project/Area Number |
17570059
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Animal physiology/Animal behavior
|
|---|
| Research Institution | Shimane University |
|---|
Principal Investigator |
OZAKI Koichi Faculty of Life and Environmental Science, Professor, 生物資源科学部, 教授 (90194539)
|
|---|
| Project Period (FY) |
2005 – 2006
|
| Keywords | Pigment cell / Drosophila melanogaster / Retina / Retinoid / Fatty acid-binding protein / Retinol-binding protein / Photoreception / Vision |
|---|
| Research Abstract |
Pigment cells of the Drosophila retina contain numerous pigment granules. We purified these granules and identified 2 proteins (fatty acid-binding protein (FBP) and photoreceptor/pigment cell dehydrogenase (PDH)) possibly involved in the visual cycle. To investigate the function of FBP and PDH, we first carried out immunohistochemical localization of these proteins. The results demonstrated that both proteins are localized on the surface of pigment granules as well as in the cytoplasm of retinal pigment cells. We next examined the binding activity of FBP to all-trans retinol with the use of the protein expressed in E. coli cells. The results demonstrated that retinol was specifically bound to FBP. Furthermore, we showed that FBP could be coimmunoprecipitated with PDH, suggesting that FBP and PDH would be involved in a common pathway of retinoid metabolism and directly interact with each other. We next modified the in vivo expression of FBP by overexpressing wild-type FBP or suppressing it with dsRNA. The HPLC analysis of retinoid composition in the mutant flies demonstrated that FBP is involved in the dark isomerization of 11-cis retinol to all-trans isomer. These results thus suggest that FBP and PDH are involved in the dark isomerization and oxidation of 11-cis retinol to all-trans retinal in the Drosophila retinal pigment cells, which may play a crucial role in the visual cycle like retinal pigment epithelium cells in the vertebrate eye.
|
