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Dylan Audette, Melinda Duncan; Prox1 may regulate growth factor receptor expression during lens fiber differentiation. Invest. Ophthalmol. Vis. Sci. 2013;54(15):463.
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© ARVO (1962-2015); The Authors (2016-present)
The regulation of the cell fate decisions leading to lens differentiation is an ongoing area of research in developmental biology. Deletion of the transcription factor Prox1 from the lens results in the failure of primary fiber cell differentiation, however the mechanisms by which Prox1 regulates lens fiber cell differentiation are unclear. Here we use a combination of candidate gene and unbiased approaches to identify the pathways that Prox1 regulates during lens fiber cell differentiation.
Mice homozygous for a floxed Prox1 allele were mated to mice expressing the MLR10 Cre transgene to delete Prox1 at the lens vesicle stage. Immunofluorescence and PCR approaches were used to test deletion of the Prox1 gene as well as differential gene and protein expression in conditional null embryos. Mutant and wild type lenses were collected proximal to Prox1 deletion by micro-dissection at 13.5 dpc and RNA was extracted. We then performed RNAseq analysis to identify differentially expressed genes.
Fiber cell differentiation failed in Prox1 mutant lenses, however the lens epithelium maintained normal expression of E-Cadherin and Pax6. Further, there was a failure to express cell cycle inhibitors Kip1/2 coincident with aberrant proliferation of fiber cell precursors. RNAseq also demonstrated mis-expression of beta and gamma crystallins as well as integral membrane proteins such as Aquaporin0 and sodium channels. Ongoing analysis of these data also indicates a role for Prox1 in regulating signaling pathways known to be involved in lens fiber differentiation including the Fibroblast Growth Factor receptors, Wnt ligands and regulators, as well as several Bmp pathway regulators.
Loss of Prox1 from the lens leads to a lack of primary fiber cell differentiation as measured by fiber cell elongation as well as a great attenuation of the expression of crystallins and other genes structurally important for fiber cell biology. Further, Prox1 appears to act in feedback loops with known signaling pathways important for lens development by regulating the expression of numerous growth factor receptors, ligands, and regulators.
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