|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1995 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1994 : ¥1,000,000 (Direct Cost : ¥1,000,000)
In this project I focused on the initial processes of the transdifferentiation of pigmented epithelial cells and asked what kind of stimuli make the pigment cells lose their stable phenotype and move into a "dedifferentiated state", which further proceeds to transdifferentiation into the lens cells. Utilizing retinal pigmented epithelial cells of chick embryos as a model system, factors considered to be important in dedifferentiation process were studied. At the same time, I asked what kind of roles such factors play in the lens regeneration process in the newt.
In cultured cells, I found that the dedifferentiation of pigmented epithelial cells is associated with i) a loss of gap junctional cell-to-cell communication, ii) a shift of the gene expression pattern in favor of degradation of extracellular matrix, iii) a loss of cellular interaction and adhesion with extracellular matrix through integrins. Also shown are iv) differentiation of pigmented epithelial cells is inhibited by adding either anti-beta1-integrin antibody or TGFbeta and v) reconstitution of extracellular matrix is accompanied in the latter case, the relationship between these changes and dedifferentiation, however, remained unknown. In the newt iris, I found a significant loss of gap junctions in the dorsal iris, but the loss was preceded by an increase of gap junctions throughout iris. The incresae was accompanied by an increased expession of a connexin gene, but the decrease should be regulated at protein level.
Above results shed light on the dedifferentiated pigmented epithelial cells, especially in relation to the extracellular matrix. At the same time, results in the newt showed that there are two phases in the early process of regeneration. Incorporation of results on cell culture must lead to a clearer understanding of the regeneration processes.