Stathmin expression during newt retina regeneration.

Japanese common newts (Cynops pyrrhogaster) have high ability to regenerate their injured organs including neural tissues, for example, the neural retina belonging to central nervous system. We attempted to clarify the molecular mechanism underlying the formation of a neural network during newt retina regeneration, and focused on the microtubule dynamics controlled by stathmin family proteins. Stathmin is a small cytoplasmic phosphoprotein known to be a microtubule regulator. We isolated a clone encoding stathmin from the newt. The expression level of stathmin is higher in lung and spleen than in the adult intact retina where stathmin was localized on plexiform layers, the ganglion layer and in photoreceptor inner segments. However, in a regenerating process of the retina, stathmin was upregulated from an early regenerating stage until the retinal layered structure was formed. Immunohistochemical analyses revealed that stathmin existed all around the regenerating retina consisting of retinal progenitor cells. These results suggest that stathmin plays important roles in the construction and maintenance of retinal structure and its neural network, by controlling the proliferation of retinal progenitor cells and the microtubule dynamics of retinal neurons. Moreover, stathmin may function in the dedifferentiating process of retinal pigment epithelium cells.