1991 Fiscal Year Final Research Report Summary

Studies on the Regulation of Immune Functions by Growth Hormone.

Research Project

Project/Area Number	02671027
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Biological pharmacy
Research Institution	National Institute of Hygienic Sciences
Principal Investigator	TERAO Tadao National Institute of Hygienic Sciences, Division of Drugs, Director, 薬品部, 部長 (60012605)
Project Period (FY)	1990 – 1991
Keywords	Growth hormone / Growth hormone receptor / IM-9 cells / Monoclonal antibodies / Ubiquitin / Down-regulation / Phorbol diesters / Phosphorylation
Research Abstract	Growth hormone-dependent proliferation of IM-9 cells under low-serum conditions was inhibited by the addition of phorbol diesters. The phorbol diesters were found to down-regulate the growthhormone receptor levels. These regulations by phorbol diesters were inhibited by staurosporine or sphingosine, suggesting the involvement of C-kinases. It was also found that phosphorylation of a 55 kDa protein, which was associated with HGHR, was increased. Monoclonal anti-peptide antibodies against human growth hormone receptor(HGHR)were prepared and characterized. Among them, the monoclonal antibody GHRP2-88 was reactive with the extracellular domain of HGHR and the most efficient when used for immunoblotting of IM-9 cell membrane proteins. Monoclonal antibodies against ubiquitin were prepared for the purpose of elucidating the role of hGHR-bound ubiquitin.