Mechanisms controlling stabilization of differentiation and transdifferentiation in the animal tissue cell.

通过1992 - 1994三个会计年度的研究，得出以下结论：鸡视网膜色素上皮细胞（RPECs）表达一种编码tgf - β结合蛋白的基因，可通过选择性剪接产生5.0kb和6.0kb的mrna。分泌5.0kb mRNA产物，6.0kb mRNA产物与RPECs的细胞外基质（ECM）结合。这两种产物通过调节RPECs自身分泌的tgf - β的功能，在体外调节RPECs的细胞状态和转分化。研究还发现bFGF是调控RPECs tgf β及其结合蛋白表达的主要因子之一。此外，一种诺贝尔丝氨酸蛋白酶抑制剂已被发现在RPECs中特异性表达，并在该细胞类型的功能分化和功能维持中发挥重要作用。2. 成熟的人RPECs在分离和培养时可以很容易地转分化为晶状体细胞，除此之外，已经清楚地证明，来自80岁的人RPECs的克隆细胞系可以表达神经丝蛋白，并可以转分化为神经元表型。这一结果首次证明，在适当的条件下，成人的RPEC也能自发地转分化为神经元细胞。3. 研究发现，RPECs对细胞培养条件非常敏感，特别是在培养基中加入血清。通过对RPECs和虹膜色素上皮细胞（ipec）在培养中的详细比较，ipec的敏感性要低得多，并且在体外可以稳定维持。在此基础上，利用1日龄鸡ipec建立了更强大的晶状体转分化细胞培养体系。该系统将为今后转分化研究的进一步发展做出贡献。

Through studies for three fiscal years from 1992 to 1994, the following results were obtained.1.A gene encoding TGFbeta-binding protein, which is expressed by chicken retinal pigmented epithelial cells (RPECs), produces 5.0kb and 6.0kb mRNAs by alternative splicing. The 5.0kb mRNA product is secreted and the 6.0kb mRNA product binds to extracellular matrix (ECM) of RPECs. Both products regulate the cell state and transdifferentiation of RPECs in vitro through modulating function of TGFbeta secreted by RPECs themselves. It has been also found that bFGF is one of major factors regulating RPECs in their expre-ssion of TGFbeta and its binding protein. In addition, a nobel serine-protease inhibitor has been found to be specifically expressed by RPECs and play essential roles in functional differentiation and maintenance of function of this cell type. 2. In addition to the fact that mature human RPECs can readily transdiffe-rentiate into lens cells when dissociated and cultured, it has been clealy demonstrated that a clonal cell line derived from 80-year-old human RPECs can express neurofilament protein submits to trans-differentiate into neuronal phenotypes. This result is the first evidence that the RPEC of even mature human can spontaneously transdifferentiate into neuronal cells under adequate conditions. 3. It has been found that the RPECs are very sensitive against cell culture condition, particularly serum added to the culture media. Through detailed comparison between RPECs and iris pigmented epithelial cells (IPECs) in culture, IPECs is much less sensitive and can be stably maintained in vitro. Based on this finding, much more powerful cell culture system of lens transdifferentiation has been established using one-day-old chicken IPECs. This system must contribute to future progress of our studies on transdifferentiation.