Epigenetic regulation in the commitment of progenitor cells during retinal development and regeneration

Molecular Signatures Integral to Natural Reprogramming in the Pigment Epithelium Cells after Retinal Detachment in Pleurodeles waltl

The reprogramming of retinal pigment epithelium (RPE) cells into retinal cells (transdifferentiation) lies in the bases of retinal regeneration in several Urodela. The identification of the key genes involved in this process helps with looking for approaches to the prevention and treatment of RPE-related degenerative diseases of the human retina. The purpose of our study was to examine the transcriptome changes at initial stages of RPE cell reprogramming in adult newt Pleurodeles waltl. RPE was isolated from the eye samples of day 0, 4, and 7 after experimental surgical detachment of the neural retina and was used for a de novo transcriptome assembly through the RNA-Seq method. A total of 1019 transcripts corresponding to the differently expressed genes have been revealed in silico: the 83 increased the expression at an early stage, and 168 increased the expression at a late stage of RPE reprogramming. We have identified up-regulation of classical early response genes, chaperones and co-chaperones, genes involved in the regulation of protein biosynthesis, suppressors of oncogenes, and EMT-related genes. We revealed the growth in the proportion of down-regulated ribosomal and translation-associated genes. Our findings contribute to revealing the molecular mechanism of RPE reprogramming in Urodela.

Cellular and Molecular Triggers of Retinal Regeneration in Amphibians

Understanding the mechanisms triggering the initiation of retinal regeneration in amphibians may advance the quest for prevention and treatment options for degenerating human retina diseases. Natural retinal regeneration in amphibians requires two cell sources, namely retinal pigment epithelium (RPE) and ciliary marginal zone. The disruption of RPE interaction with photoreceptors through surgery or injury triggers local and systemic responses for retinal protection. In mammals, disease-induced damage to the retina results in the shutdown of the function, cellular or oxidative stress, pronounced immune response, cell death and retinal degeneration. In contrast to retinal pathology in mammals, regenerative responses in amphibians have taxon-specific features ensuring efficient regeneration. These include rapid hemostasis, the recruitment of cells and factors of endogenous defense systems, activities of the immature immune system, high cell viability, and the efficiency of the extracellular matrix, cytoskeleton, and cell surface remodeling. These reactions are controlled by specific signaling pathways, transcription factors, and the epigenome, which are insufficiently studied. This review provides a summary of the mechanisms initiating retinal regeneration in amphibians and reveals its features collectively directed at recruiting universal responses to trauma to activate the cell sources of retinal regeneration. This study of the integrated molecular network of these processes is a prospect for future research in demand biomedicine.