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S. Wang, W. Xie; Synergism Between cath5 and cNSCL1 in Promoting Retinal Ganglion Cell Differentiation . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1604.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: . The molecular mechanism underlying retinal ganglion cell differentiation is largely unknown. Published studies indicate that immature retinal ganglion cells express cath5 and cNSCL1, genes encoding proteins of the bHLH family of transcription factors. Mouse ath5 has been shown to be indispensable for retinal ganglion cell development. In this study we examine whether the two genes act synergistically to promote retinal ganglion cell development. Methods: The coding sequences of cath5 and cNSCL1, with IRES in between, were inserted into retrovirus RCAS. For in vitro study, RPE cells were isolated from day 6 chick embryos and cultured as dissociated cells. The culture was inoculated with RCAS virus expressing cath5 + cNSCL1, and the infected cultures were immunostained with retinal ganglion cell markers. For in vivo study, viral particles were microinjected into the subretinal space of chick embryos. At later stages, retinal cells were dissociated, seeded onto poly-ornithine treated dishes, and subjected to double-immunostaining to identify retinal ganglion cells (Brn3A+ or Islet-1+) that had been infected with the virus. Data from cath5 + cNSCL1 retina were compared with that of cath5 retina and cNSCL1 retina. Results: While either cath5 or cNSCL1 promoted bFGF-initiated RPE transdifferentiation towards retinal ganglion cells, the extent of differentiation was rather limited as a large portion of the transdifferentiating RPE cells lacked typical retinal ganglion cell morphologies. With ectopic expression of cath5 + cNSCL1, transdifferentiating RPE cells exhibited extensive cellular differentiation with long, thin processes typical of retinal ganglion cells. In the developing retina, there were about 3x more Brn3A+ cells with misexpression of cath5 + cNSCL1 than misexpression of either gene alone. The number of Islet-1+ cells in cath5 + cNSCL1 retina was 1.6x and 3x of that in cath5 retina and cNSCL1 retina, respectively. Conclusions: Both in vitro and in vivo data suggest that cath5 and cNSCL1 play important, yet distinctive roles in retinal ganglion cell differentiation and together they promote extensive retinal ganglion cells differentiation.
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