[An analysis of keratin expression in the cells of the retinal pigment epithelium during transdifferentiation in newts].

Keratins of the cytoskeletal intermediate filaments have been identified immunohistochemically in pigment epithelium cells of the adult newt retina. We studied the expression of keratins in transdifferentiating and redifferentiating cells of the retinal pigment epithelium at different periods after removal of the retina. We have shown that the expression of keratins decreases. This appears as the decreased intensity of the immunospecific reaction soon after the operation. The latter observation has also been made immediately after artificial dissociation of the pigment epithelium cells of the retina isolated from nonoperated newt eyes. We found that the immunostaining of keratins was absent in the cells of normal and regenerating retina, as well as in retinal pigment epithelium cells before restoration of their structural and functional relationship with the retinal regenerate. The results obtained provide evidence for the inhibition of keratins expression during the transformation of retinal pigment epithelium into the retina. We proposed that there exists a mechanism responsible for gradual replacement of keratins by proteins of neurofilaments that have earlier been identified at the beginning of transdifferentiation of the retinal pigment epithelium.