Abstract
Purpose :
Besides their structural and physiological supporting roles for the neural retina, müller glia behave like stem cells in injured retina in lower vertebrates by returning to a retinal progenitor-like state to regenerate all types of retinal cells. However, such regeneration ability is almost abolished in mammals. The aim of this study is to explore mechanisms restricting regeneration ability of mouse müller cells by comprehensively characterize the molecular features of müller cells in both physiological and pathological (injury and aging) conditions, at the transcriptome level and the DNA methylome level.
Methods :
Müller cells of young adult mice, 1.5-year-old mice, as well as from NMDA-injured retinas of young adult mice were purified from Rlbp1-GFP mice by FACS. Retinal progenitor cells (RPC) were collected from embryonic day 12.5 mouse embryos. RNA-seq was used to sequence the transcriptomes. RRBS was used to sequence the methylomes.
Results :
The müller cell transcriptome was enriched for GO terms such as visual perception and ion transport, consistent with the physiological supporting functions of müller cells. Meanwhile, müller transcriptome was dramatically depleted of the group of genes that drive cell cycle progression when compared to RPC transcriptome. In addition, many important neurogenic factors, such as Ascl1 and Lin28, were absent in müller cells. Injury stimulated the expression of a large number of genes, however, most cell cycle regulatory genes and neurogenic factors remain poorly expressed in müller cells. Transcriptome changes during aging were trivial, but largely overlapped with those during injury. CpG methylome analysis revealed a more demethylated genome of müller cell compared with RPC genome, and many müller cell specific genes underwent demethylation during RPC-to-müller differentiation, suggesting that proper control of DNA methylation was involved in the development and physiological functions of müller cells.
Conclusions :
The comprehensive transcriptome and methylome comparison between mouse müller cells and RPCs showed that the two cell types were significantly different from each other, and cell cycle regulatory networks and neurogenic factors seem to be two of the key roadblocks for the regeneration activity of müller cells.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.