|Budget Amount *help
¥4,700,000 (Direct Cost : ¥4,700,000)
Fiscal Year 1994 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1992 : ¥2,600,000 (Direct Cost : ¥2,600,000)
We studied about cell responses after growth factor or differentiation factor stimulation on the aspect of synthesis of second messengers. Especially on phosphatidylinositol-3 kinase (PI3K), which is activated immediately after growth factor stimulation. First, to see the role of each domains, we produced the monoclonal antibodies to the various part of the 85kD subunit (p85). We have previously produced the antibodies to amino-terminal two third of the alpha type p85, however, there were no antibodies to the carboxyl-terminal portion of p85. We made such antibodies by immunizing mice with the peptides the corresponding to carboxyl-terminal portion of p85. Using the obtained antibodies, we analyzed the expression of p85 in various cell lines obtained from human cancers. One of the cell lines, HCC2998, expressed the smaller p85s instead of the wild type. The study on relationship between cell transformation and the mutation is now underway. For another subunit, p110, we have not succeeded in the production of the monoclonal antibodies.
We also studied on the role of PI3K in osteoclasts. Inhibition of PI3K by a specific inhibitor, wortmannin, resulted in blockage of bone resorption.It appeared that the ruffled borders were not formed after inhibition of Pl3K.At the same time, the podosome, an F-actin structure specifically formed in osteoclasts, was lost. Stress fibers in the fibroblasts were not affected. These results suggest that the actin rearrangement is controlled strictly and that PI3K is involved in the control. The relationship between formation of podosomes and ruffled border is being studied.