ZFIN ID: ZDB-PUB-191012-5
Brain-specific homeobox Bsx specifies identity of pineal gland between serially homologous photoreceptive organs in zebrafish
Mano, H., Asaoka, Y., Kojima, D., Fukada, Y.
Date: 2019
Source: Communications biology   2: 364 (Journal)
Registered Authors: Fukada, Yoshitaka, Kojima, Daisuke
Keywords: Cell type diversity, Cellular neuroscience, Evolutionary developmental biology, Retina
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Gene Expression Regulation, Developmental
  • Homeodomain Proteins/metabolism
  • Otx Transcription Factors/metabolism
  • PAX6 Transcription Factor/metabolism
  • Pineal Gland/cytology
  • Pineal Gland/growth & development
  • Pineal Gland/metabolism*
  • Promoter Regions, Genetic
  • Trans-Activators/metabolism
  • Transcription Factors/metabolism
  • Zebrafish
  • Zebrafish Proteins/metabolism
PubMed: 31602413 Full text @ Commun Biol
The pineal gland functioning as a photoreceptive organ in non-mammalian species is a serial homolog of the retina. Here we found that Brain-specific homeobox (Bsx) is a key regulator conferring individuality on the pineal gland between the two serially homologous photoreceptive organs in zebrafish. Bsx knock-down impaired the pineal development with reduced expression of exorh, the pineal-specific gene responsible for the photoreception, whereas it induced ectopic expression of rho, a retina-specific gene, in the pineal gland. Bsx remarkably transactivated the exorh promoter in combination with Otx5, but not with Crx, through its binding to distinct subtypes of PIRE, a DNA cis-element driving Crx/Otx-dependent pineal-specific gene expression. These results demonstrate that the identity of pineal photoreceptive neurons is determined by the combinatorial code of Bsx and Otx5, the former confers the pineal specificity at the tissue level and the latter determines the photoreceptor specificity at the cellular level.