ZFIN ID: ZDB-PUB-170215-5
Rainbow Enhancers Regulate Restrictive Transcription in Teleost Green, Red, and Blue Cones.
Fang, W., Guo, C., Wei, X.
Date: 2017
Source: The Journal of neuroscience : the official journal of the Society for Neuroscience   37(11): 2834-2848 (Journal)
Registered Authors: Fang, Wei, Wei, Xiangyun
Keywords: crumbs, nagie oko, photoreceptor, ponli, promoter, rainbow enhancer
MeSH Terms:
  • Animals
  • Cone Opsins/genetics*
  • Fishes/classification
  • Fishes/genetics*
  • Gene Expression Regulation/genetics
  • Membrane Proteins/genetics*
  • Membrane Proteins/metabolism
  • Regulatory Elements, Transcriptional/genetics
  • Retinal Cone Photoreceptor Cells/physiology*
  • Species Specificity
  • Transcriptional Activation/genetics*
  • Zebrafish/genetics*
  • Zebrafish Proteins/genetics*
  • Zebrafish Proteins/metabolism
PubMed: 28193687 Full text @ J. Neurosci.
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ABSTRACT
Photoreceptor-specific transcription of individual genes collectively constitutes the transcriptional profile that orchestrates the structural and functional characteristics of each photoreceptor type. It is challenging, however, to study the transcriptional specificity of individual photoreceptor genes because each gene's distinct spatiotemporal transcription patterns are determined by the unique interactions between a specific set of transcription factors and the gene's own cis-regulatory elements (CREs), which remain unknown for most of the genes. For example, it is unknown what CREs underlie the zebrafish mpp5b(ponli) (ponli) and crumbs2b (crb2b) apical polarity genes' restrictive transcription in the red, green, and blue (RGB) cones in the retina, but not in other retinal cell types. Here we show that the intronic enhancers of both the ponli and crb2b genes are conserved among teleost species and that they share sequence motifs that are critical for RGB cone-specific transcription. Given their similarities in sequences and functions, we name the ponli and crb2b enhancers collectively rainbow enhancers. rainbow enhancers may represent a cis-regulatory mechanism to turn on a group of genes that are commonly and restrictively expressed in RGB cones, which largely define the beginning of the color vision pathway. SIGNIFICANCE STATEMENT Dim-light vision and bright-light color vision are initiated in rod and several types of cone photoreceptors, respectively; these photoreceptors are structurally distinct from each other. In zebrafish, although quite different from rods and UV cones, RGB cones (red, green, and blue cones) are structurally similar and unite into mirror-symmetric pentamers (G-R-B-R-G) by adhesion. This structural commonality and unity suggests that a set of genes is commonly expressed only in RGB cones but not in other cells. Here, we report that the rainbow enhancers activate RGB cone-specific transcription of the ponli and crb2b genes. This study provides a starting point to study how RGB cone-specific transcription defines RGB cones' distinct functions for color vision.
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