High impact information on OTX2

• Implication of OTX2 in pigment epithelium determination and neural retina differentiation [1].
• Bromodeoxyuridine labeling in combination with immunohistochemistry with anti-OTX2 antiserum and different cell-specific markers were used to determine that OTX2-positive cells are postmitotic neuroblasts undergoing differentiation into several, if not all, of the distinct cell types present in the chick retina [1].
• Early on, Otx2 expression was diffuse throughout the optic vesicles but became restricted to their dorsal part when the vesicles contacted the surface ectoderm [1].
• Specification of the meso-isthmo-cerebellar region: the Otx2/Gbx2 boundary [2].
• Different combinations of signals are responsible for different aspects of this early transient induction: FGF initiates expression of Sox3 and ERNI, retinoic acid can induce Cyp26A1 and only a combination of low levels of FGF8 together with Wnt- and BMP-antagonists can induce Otx2 [3].

Biological context of OTX2

• A distinct preisthmic histogenetic domain is defined by overlap of Otx2 and Pax2 gene expression in the avian caudal midbrain [4].
• This was accompanied by down-regulation of Otx2 and BMP7, which implicates that these factors are essential for choroid plexus specification and differentiation [5].
• During development, a burst of Otx2 mRNA closely matched the timing of HIOMT gene activation in these two tissues [6].

Anatomical context of OTX2

• The parvicellular isthmic nucleus, although placed inside the midbrain lobe, never expressed Otx2, and its cells rapidly down-regulated an early transient Pax2 signal; this pattern is consistent with its reported isthmic origin and forward tangential translocation [4].
• The torus semicircularis-the inferior colliculus homolog-expressed Otx2 in its ventricular lining exclusively, but it never expressed Pax2 [4].
• The Otx2 expression was detected in the ventro-lateral wall of the otic anlage and could play a role in the segregation of the saccule and utricle maculae [7].
• Moreover, CNBP and Otx2 may play roles as regulators of forebrain formation in two parallel pathways [8].
• In the neural retina, Otx2 immunoreactivity brightly decorated the photoreceptor nuclei and extended more faintly to the outer half of the inner nuclear layer [6].

Regulatory relationships of OTX2

• These presumably result from step-like isthmic organizer effects on Otx2-expressing midbrain neuroepithelium at different distances from a caudal FGF8 morphogen source (isthmic Fgf8-positive domain) [4].

Other interactions of OTX2

• We propose a new nomenclature to differentiate the vesicles and constrictions observed in the avian MH domain at stage HH10 and HH20, based on the localization of the Gbx2/Otx2 common boundary [9].

References