Cell growth and second messengers

我们从第二信使的合成方面研究了生长因子或分化因子刺激后细胞的反应。特别是对磷脂酰肌醇-3激酶（PI 3 K），其在生长因子刺激后立即活化。首先，为了了解每个结构域的作用，我们制备了针对85 kD亚基（p85）各个部分的单克隆抗体。我们以前已经产生了针对α型p85氨基端三分之二的抗体，然而，没有针对p85羧基端部分的抗体。我们通过用对应于p85羧基末端部分的肽免疫小鼠来制备这样的抗体。使用获得的抗体，我们分析了p85在从人类癌症获得的各种细胞系中的表达。其中一个细胞系HCC 2998表达较小的p85而不是野生型。细胞转化和突变之间的关系的研究正在进行中。对于另一个亚基p110，我们还没有成功地制备出单克隆抗体。抑制PI 3 K可导致骨吸收障碍，但抑制PI 3 K后，骨吸收障碍的边缘消失，同时破骨细胞内特有的F-肌动蛋白结构--足体消失。成纤维细胞中的应力纤维不受影响。这些结果表明肌动蛋白重排受到严格控制，并且PI 3 K参与了控制。足状体的形成与皱边的关系正在研究中。

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.