Abstract
Purpose :
Leukemia Inhibitory Factor (LIF) is a potent neuroprotective factor induced in Müller glial cells in response to retinal injury. LIF induction has been shown to prevent retinal degeneration. However, the mechanism for LIF induction is unknown. The purpose of this study is to determine the epigenetic and transcript profile of the LIF locus in Müller glial cells utilizing cell-specific molecular tools and high-throughput data sets.
Methods :
GLAST-Cre and Rodi75-Cre mouse lines were crossed with RPL22:HAf/+ or Sun1-sfGFP f/+ mice to generate tagged Müller glia or rod photoreceptors, respective. Mice were injected with TNFα to induce LIF expression. PBS-injected animals were used as control. Chromatin immunoprecipitation analysis (ChIP) was performed on cell selective nuclei using antibodies against NF-κB, cFOS, H3K4me3, H3K27me3 and IgG. For RNA analysis, retinas were homogenized, polysome-associated RNA was precipitated by αHA, and purified for analysis by qRT-PCR. Publically available ChIP-seq, transposase-accessible chromatin ATAC-seq and RNA-seq datasets (GSE87064, GSE83312, GSE35386 and GSE94534) were used to correlate LIF expression to mapped promoter and transcriptional start sites.
Results :
The promoter-specific H3K4me3 was enriched at DNA regions corresponding to a downstream LIF promoter in Müller glia, but not in rods. ATAC-seq and ChIP-seq analyses demonstrates that this was a region of open chromatin and binding sites for transcription factors, NF-κB and cFOS were found within the first intron of the LIF gene. Expression of this LIF transcript was enriched in Müller glia, but not in photoreceptors. In addition, our meta-analysis demonstrates that over 1500 genes correlated with LIF expression in Müller glia.
Conclusions :
Our data demonstrates that the downstream LIF promoter is induced in Müller glia under stress conditions. The ATAC-seq and ChIP-seq analyses identify important regulatory elements within the LIF gene body. Our meta-analysis suggests that LIF induction suggests a common transcriptional network for Müller cell stress response.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.