1998 Fiscal Year Final Research Report Summary
Studies on the transfer machinery of sugar transfer in the placeental barrier.
| Project/Area Number |
08671869
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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 |
Obstetrics and gynecology
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| Research Institution | GUNMA UNIVERSITY |
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Principal Investigator |
FUJIKURA Keiko Institute for Molecular and Cellular Regulation, Department of Cell Biology, Research assisatnt, 生体調節研究所, 教務員 (10218993)
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| Co-Investigator(Kenkyū-buntansha) |
TAKATA Kuniaki Institute for Molecular and Cellular Regulation, Department of Cell Biology, Pro, 生体調節研究所, 教授 (20129290)
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| Project Period (FY) |
1996 – 1998
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| Keywords | placenta / glucose transporter / GLUT1 / GLUT3 / gap junction / syncytiotrophoblast / placental barrier / connexin 26 |
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| Research Abstract |
In order to elucidate the molecular mechanism of- sugar transfer in the placenta, we analyzed the localization of 'glucose transporter GLUT1, GLUT3, and gap junction proteins connexins in the rat placenta by immunohistochemical methods. Anti-rat GLUT3 antibody was raised using synthetic peptides corresponding to the isoform- specific stretch of GLUT3 molecules. GLUT1 was found in all, part of the placenta, whereas GLUT3 was restricted to the labyrinthine region, a site of materno-fetal transfer of sugars. Two layers of syncytiotrophoblasts (I and II from the maternal-blood side) constitute the barrier in the labyrinth, where both GLUT1 and GLUT3 were abundant. Immunogold electron microscopy revealed that GLUT1 was localized at the maternal-side plasma membrane of syncytiotrophoblast I and the fetal-side plasma membrane of, syncytiotrophoblast II.GLUT3 was localized at the at the maternal- side plasma membrane of syncytiotrophoblasts I and II.Syncytiotrophoblasts I and II were connected by numerous gap junctions made of connexin 26. These observations suggest that 1) both GLUT1 and GLUT3 serve in the entry of sugars into the cells of the placental barrier ; 2) gap junctions of connexin 26, hydrophilic channels connecting the cytoplasm of syncytiotrophoblasts I and II, serve as routes of sugar transfer in the barrier ; 3) GLUT1 serves as a transporter of sugars for the exit from the barrier. Recent connexin 26 knock-out experiment supports the above model. In addition, asymmetrical localization of GLUT3 in the placental barrier may serve for the polarized transfer of sugar across the placental barrier, possibly facilitates the stabilization of the fetal blood sugar level.
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