By contrast, lin 28 was significantly up regulated further info only in the presence of FGF2 in retinecto mized eyes. Moreover, Lin 28 overexpression in the injured RPE was sufficient to induce RPE transdifferentiation. These results establish a two step dedifferentiation Inhibitors,Modulators,Libraries process. First, upon injury there is an activation of gene expression for sox2, c myc and klf4, concomitantly with the up regulation of eye field transcriptional factors. Sec ond, in the presence of FGF2, lin 28 is up regulated, suggesting a correlation between the expression of lin 28 and the process of transdifferentiation. Overexpression of Lin 28 in the injured RPE was sufficient to induce RPE transdifferentiation in the absence of an external source of growth factors.

To our knowledge, these data provide the first evidence that Lin 28 plays an important role in retina regeneration via RPE trans Inhibitors,Modulators,Libraries differentiation. This is also the first detailed study on the molecular profile of the RPE during the process of dedifferentiation. Results and discussion Expression of pluripotency inducing factors in the ciliary margin and retinal pigmented epithelium To dissect the possible role of pluripotency inducing factors during RPE transdifferentiation, we decided first to analyze the expression of these factors in E4 eyes. The pres ence of transcripts was analyzed by reverse transcriptase polymerase chain reaction from RNA collected from the ciliary margin or RPE. In order to keep the integ rity and specificity of all the tissues collected, we used laser capture microdissection.

We found that sox2, c myc, klf4 and lin 28 mRNAs were expressed in the ciliary mar gin, Inhibitors,Modulators,Libraries while only klf4, c myc and lin 28 were detected in the RPE. Consistent with the RT PCR analysis, immunofluorescence staining demonstrated that Sox2, c Myc, Klf4 and Lin 28 were present in both the ciliary margin and neuroepithelium. By contrast, only Klf4, c Myc and Lin 28 were present in the RPE at E4 and E7. In agreement with our results, Sox2 has been reported to be expressed in the presumptive neural retina and is down regulated in the presumptive RPE at E4 to 4. 5. Among these factors, it has been reported that Klf4 plays a critical role in neurogenesis and neural migration during cerebral cortex development in mouse. It could be possible that Klf4 has a similar role in retina development.

In chick embryos, klf4 mRNA was de tected in the neural folds and in the neural tube at Stages 8 to 9. Later, at Stage 27, klf4 was detected in the face and neck region. In our experiments, we de tected Klf4 ubiquitously in Inhibitors,Modulators,Libraries the ciliary margin, neuroepi thelium and RPE. In chicken embryos, Lin 28 is ubiquitously expressed Inhibitors,Modulators,Libraries in the presumptive limb primordium at Stages 15 to 16, and in other tissues including the neuroepithelium selleck bio of the optic cup and in the otic vesicle at E2. 5 to 3. In mouse, Lin 28 is present in the retina at em bryonic days E8. 5 to E17. 5.