The Effect of Colchicine on the Induction of the Stellate Configuration in Dorsal Iris Epithelial Cells of the Newt Notophthalmus viridescens, in vitro

Abstract

Summary Treatment of cultured cells derived from the dorsal iris of the newt, Notophthalmus viridescens, with cAMP or substances which increase intracellular levels of cAMP induces a transient but striking change in the cells’ morphology [1, 2]. The resultant formation of fine cytoplasmic projections radiating from the cell centre has been called the stellate configuration [1, 2], and it has been suggested that similar processes occur during depigmentation and cellular dedifferentiation during lens regeneration in vivo [1, 2]. The present study was undertaken to determine if microtubules play a role in the formation of the stellate configuration in iris epithelial cells in vitro. Thus, cells derived by outgrowth from iris tissue explants were treated with a variety of agents to induce the stellate configuration. The most effective agents tested were papaverine and adenosine. Subsequently cells were treated with the inducing agents adenosine and papaverine, and the drug colchicine. Colchicine caused a disruption or modification of the stellate configuration, except in cases where very high doses of the inducing agents were used. When cells were first treated with the inducing agents, followed 80 min later by colchicine treatment, the stellate configuration was rapidly lost. These results strongly suggest that microtubules are involved in the production of the stellate configuration in iris epithelial cells in vitro and are thus implicated in the depigmentation and dedifferentiation responses in lens regeneration in vivo.