1999 Fiscal Year Final Research Report Summary
Studies on the placental PRL-like molecules and their target cells
| Project/Area Number |
10460121
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied animal science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SHIOTA Kunio The Univ. of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (80196352)
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| Co-Investigator(Kenkyū-buntansha) |
OGURA Atsuo A. O. Lab of Vet Sci, National Institute of Infectious Diseases, Researcher, 獣医科学部, 主任研究員
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| Project Period (FY) |
1998 – 1999
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| Keywords | rat / placenta / pregnancy / PRL / PRL-H / SSP / PL-Im / baculovirus |
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| Research Abstract |
The placenta acts as a multi-function organ in the maintenance of pregnancy and in fetal growth. Rat placenta produces several members of the placental prolactin (PRL) family that show structural similarities to pituitary PRL. To date more than ten members of the placental PRL family have been cloned, and they are categorized into two subfamilies according to their Structure and function; the placental lactogen (PL) subfamily and like protein (PLP) subfamily. PRL exerts its biological function through the PRL receptor (PRL-R). PL subfamily members are also able to bind to the PRL-R and to stimulate the proliferation of Nb2 cells. Some members of PLP sub family do not bind to PRL-R nor do they stimulate lactogenic activity even though they are structura11 similar to PRL, implying that there may be yet unknown specific receptors for the PRL family members. To further understand the mechanisms underlying the expression of biological activities of PRL family members, we first evaluated the biological activity of recombinant PL-Im (recPL-Im) produced by means of a baculovirus/insect cell expression system The recPL-Im showed not only an ability to bind to PRL-R and express PRL-like activity, demonstrated by the Nb2 cell proliferation assay, but also showed luteotropic hormone (LH)-like activity in vitro. We then evaluated the role of N-linked oligosaccharides in the mo1ecular action of recPL-Im and found that the ability of PL-Im to bind PRL receptor is independent of the N-glycosylation although it appeared to be relevant for expressing PRL-like activity in the Nb2 cell proliferation assay. These results raised the possibility that recPL-Im may also act through unidentified receptor system besides the PRL-R. In this study we also performed of cDNAs for rat placenta-specific cytokines/ hormones, and isolated a novel member of PLP subfamily, named PLP-H, as well as a novel secretory protein, SSP.
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