Retina is the neural tissue of the eye. The light crosses the thickness of the retina before striking and activating the photoreceptors (rods and cones). Photoreceptors are the first conversion contact point between the nervous system and the external environment. Photoreceptors exchange light energy into patterned neuronal signals. During retinal development, retinal progenitor precursors are committed to photoreceptor cell fate through a set of transcription factors. Thus far, a critical role has been assigned to the OTX2 homeo-domain transcription factor, which activates expression of another homeo-domain transcription factor, cone-rod homeobox (CRX). CRX is a key transcription factor in both developing and adult photoreceptors. Among distinct retinal-specific gene targets, CRX regulates RHODOPSIN (RHO). RHO is the most abundantly expressed rod-specific gene, accounting for about 90% of all proteins in the rod outer segment. In particular, RHO represents the photon-capture protein, which triggers the phototransduction cascade conversion. This study is aimed at integrating the cis-regulatory regions of the retinal specific transcription factor CRX binding and the epigenetic mark Histone3 lysine9 trimethylation (H3K9me3) in both RHO locus and genome wide in the porcine retinal model. Chromatin immunoprecipitations (ChIP) studies showed that CRX binds extensively in both putative regulative and gene body regions of RHO. These binding maps are associated with an enrichment of the epigenetic modification, H3K9me3 along the RHO gene body length. We found that the H3K9me3 enrichment increase progressively from the 5' to 3' of the gene. This finding is consistent with the notion that the H3K9me3 signature is present in the gene body of highly expressed genes, such as RHO. H3K9me3 histone modification promotes both the precise transcriptional start and elongation steps through the positive interaction with RNA polymerase II elongation machinery. Since we are interested in correlating local to global transcriptional regulator marks in porcine retina, currently we are mapping genome wide both H3K9me3 and CRX binding using ChIP-sequencing (ChIP-seq). This study will generate insights into the cross-talk between the genome and the epigenome of photoreceptor transcriptional machinery.
Physical mappaing of a retinal-specific trascription factor and the epigenetic mark H3K9me3 correlated to rhodopsin and genome wide retinal loci.
Matarazzo MR;Della Ragione F;D'Esposito M;
2014
Abstract
Retina is the neural tissue of the eye. The light crosses the thickness of the retina before striking and activating the photoreceptors (rods and cones). Photoreceptors are the first conversion contact point between the nervous system and the external environment. Photoreceptors exchange light energy into patterned neuronal signals. During retinal development, retinal progenitor precursors are committed to photoreceptor cell fate through a set of transcription factors. Thus far, a critical role has been assigned to the OTX2 homeo-domain transcription factor, which activates expression of another homeo-domain transcription factor, cone-rod homeobox (CRX). CRX is a key transcription factor in both developing and adult photoreceptors. Among distinct retinal-specific gene targets, CRX regulates RHODOPSIN (RHO). RHO is the most abundantly expressed rod-specific gene, accounting for about 90% of all proteins in the rod outer segment. In particular, RHO represents the photon-capture protein, which triggers the phototransduction cascade conversion. This study is aimed at integrating the cis-regulatory regions of the retinal specific transcription factor CRX binding and the epigenetic mark Histone3 lysine9 trimethylation (H3K9me3) in both RHO locus and genome wide in the porcine retinal model. Chromatin immunoprecipitations (ChIP) studies showed that CRX binds extensively in both putative regulative and gene body regions of RHO. These binding maps are associated with an enrichment of the epigenetic modification, H3K9me3 along the RHO gene body length. We found that the H3K9me3 enrichment increase progressively from the 5' to 3' of the gene. This finding is consistent with the notion that the H3K9me3 signature is present in the gene body of highly expressed genes, such as RHO. H3K9me3 histone modification promotes both the precise transcriptional start and elongation steps through the positive interaction with RNA polymerase II elongation machinery. Since we are interested in correlating local to global transcriptional regulator marks in porcine retina, currently we are mapping genome wide both H3K9me3 and CRX binding using ChIP-sequencing (ChIP-seq). This study will generate insights into the cross-talk between the genome and the epigenome of photoreceptor transcriptional machinery.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
