Analysis of regulatory mechanism of various growth factors in the growth and differentiation of human keratinocytes and fibroblasts

我们的研究成果总结为三组：1)EGF家族生长因子，2)tgf - β, 3)表皮细胞分化抑制剂（EDIN）。关于EGF家族生长因子，已知tgf - α和amphiregulin是人角质形成细胞的自分泌生长因子。它们刺激人类角化细胞的生长并由人类角化细胞产生。在本研究中，我们发现肝素结合EGF样生长因子（HB-EGF）是EGF家族生长因子的新成员，也是人角质形成细胞的自分泌生长因子。免疫组织化学方法也显示HB-EGF在正常和银屑病表皮中的定位。有趣的是，研究揭示了这些EGF家族生长因子的相互刺激机制：HB-EGF或tgf - α的加入增加了HB-EGF mRNA、tgf - α mRNA和双调节蛋白mRNA的全部表达。因此，这是一种非常有效的诱导自分泌EGF家族生长因子的机制。这将是未来人类角化细胞生长调控研究的主要目标之一。关于tgf - β，我们确定了tgf - β亚型在人类皮肤中的定位。在正常人类皮肤中，tgf - β 2定位于表皮，tgf - β 3主要定位于真皮上部。有趣的是，银屑病皮损表皮中tgf - β 2的染色强度降低。这可能与银屑病的表皮增生有关。EDIN从金黄色葡萄球菌上清液中分离得到。它能抑制人酮化细胞的分化。我们证明EDIN adp核糖基化rho蛋白，小G蛋白之一，并插入其作用。

The summary of our research results was classified into three groups : 1) EGF family growth factors, 2) TGF-beta, 3) Epidermal cell diferrentiation inhibitor(EDIN). Concerning to EGF family growth factors, it was known that TGF-alpha and amphiregulin were autocrine growth factors for human keratinocytes. They stimulate the growth of human ketatinocytes and produced by human keratinocytes. In this study, we showed that heparin-binding EGF-like growth factor(HB-EGF), a new member of EGF family growth factor, is also an autocrine growth factor for human keratinocytes. The localization of HB-EGF in normal and psoriatic epidermis was also shown by immunohistochemical methods. Interestingly, an mutual stimulatory mechanism of these EGF family growth factors was revealed : the addtion of HB-EGF or TGF-alpha increased all of HB-EGF mRNA, TGF-alpha mRNA and amphiregulin mRNA.So, this is a very effecttive mechanism for induction of autocrine EGF family growth factors. It will be one of the main aims in the future study on growth regulation of human keratinocytes. Concerning to TGF-beta, we identified the localization of TGF-beta isoforms in the human skin. In the normal human skin, TGF-beta2 is localized in the epidermis and TGF-beta3 is localized mainly in the upper dermis. Interestingly, the staining intensity of TGF-beta2 was decreased in the epidermis of psoriatic lesions. This may be correlated with the epidermal hyperplasia in psorisis. Concerning to EDIN, it was purified from the supernatant of Staphylococcus aureus. It inhibits the differentiation of human ketatinocytes. We demonstrated that EDIN ADP-ribosylates rho protein, one of small G proteins and inserts its effect.