LATE PROLIFERATION OF RETINAL MULLER CELL PROGENITORS FACILITATES PREFERENTIAL TARGETING WITH RETROVIRAL VECTORS IN-VITRO

During vertebrate neural retina development, the relationship between mitotic activity in progenitor cells and the acquisition of a mature c ell phenotype remains an area of controversy. The Moller glial cell ha s long been recognized as one of the last cell types of the retina to mature, which occurs under the influence of cell-cell interactions. In this report we examine the acquisition of the Muller cell phenotype i n relation to mitotic activity. Using immunohistochemical markers, we demonstrate that a gene product characteristic of mature Muller cells, the 2M6 antigen, is expressed in mitotically active cells, even after all the major retina architectural features have been laid down. Furt hermore, we show that retroviral infection, a process that requires mi totically active cells, preferentially targets Muller cell progenitors when late embryonic retina is infected in vitro. The two lines of evi dence are consistent with a model for Muller cell differentiation that includes a mitotically active progenitor that has already begun to ex press specific differentiation gene products. (C) 1997 Wiley-Liss, Inc .