Brain-specific homeobox Bsx specifies identity of pineal gland between serially homologous photoreceptive organs in zebrafish

• DOI: 10.1038/s42003-019-0613-1
• Publication Date: 2019-10-07T10:04:19Z
• Authors: Hiroaki Mano; Yoichi Asaoka; Daisuke Kojima; Yoshitaka Fukada
• Keywords: Ectopic expression

Abstract The pineal gland functioning as a photoreceptive organ in non-mammalian species is serial homolog of the retina. Here we found that Brain-specific homeobox (Bsx) key regulator conferring individuality on between two serially homologous organs zebrafish. Bsx knock-down impaired development with reduced expression exorh , pineal-specific gene responsible for photoreception, whereas it induced ectopic rho retina-specific gene, gland. remarkably transactivated promoter combination Otx5, but not Crx, through its binding to distinct subtypes PIRE, DNA cis -element driving Crx/Otx-dependent expression. These results demonstrate identity neurons determined by combinatorial code and former confers specificity at tissue level latter determines photoreceptor cellular level.