The epithalamic region of fishes shows prominent left-right asymmetries that are executed by nodal signaling upstream of the asymmetry-determining transcription factor pitx2. Previous reports have identified that nodal controls the left-sided pitx2 expression in the lateral plate mesoderm through an enhancer present in the last intron of this gene. However, whether similar regulation occurs also in the case of epithalamic asymmetry is currently unresolved. Here, we address some of the cis-regulatory information that control asymmetric pitx2 expression in epithalamus by presenting a Tg(pitx2:EGFP) 116-17 transgenic medaka model, which expresses enhanced green fluorescent protein (EGFP) under control of an intronic enhancer. We show that this transgene recapitulates epithalamic expression of the endogenous pitx2 and that it responds to nodal signaling inhibition. Further, we identify that three foxh1-binding sites present in this enhancer modulate expression of the transgene and that the second site is absolutely necessary for the left-sided epithalamic expression while the other two sites may have subtler regulative roles. We provide evidence that left-sided epithalamic pitx2 expression is controlled through an enhancer present in the last intron of this gene and that the regulatory logic underlying asymmetric pitx2 expression is shared between epithalamic and lateral plate mesoderm regions.
- MeSH
- embryo nesavčí cytologie metabolismus MeSH
- epitalamus embryologie metabolismus MeSH
- forkhead transkripční faktory genetika metabolismus MeSH
- funkční lateralita MeSH
- homeodoménové proteiny genetika metabolismus MeSH
- introny * MeSH
- mezoderm embryologie metabolismus MeSH
- Oryzias embryologie genetika MeSH
- protein nodal genetika metabolismus MeSH
- signální transdukce MeSH
- transgeny genetika MeSH
- transkripční faktory genetika metabolismus MeSH
- vazebná místa MeSH
- vývojová regulace genové exprese * MeSH
- zelené fluorescenční proteiny genetika metabolismus MeSH
- zesilovače transkripce * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The midbrain-hindbrain boundary (MHB) is one of the key organizing centers of the vertebrate central nervous system (CNS). Its patterning is governed by a well-described gene regulatory network (GRN) involving several transcription factors, namely, pax, gbx, en, and otx, together with signaling molecules of the Wnt and Fgf families. Here, we describe the onset of these markers in Oryzias latipes (medaka) early brain development in comparison to previously known zebrafish expression patterns. Moreover, we show for the first time that vox, a member of the vent gene family, is expressed in the developing neural tube similarly to CNS markers. Overexpression of vox leads to profound changes in the gene expression patterns of individual components of MHB-specific GRN, most notably of fgf8, a crucial organizer molecule of MHB. Our data suggest that genes from the vent family, in addition to their crucial role in body axis formation, may play a role in regionalization of vertebrate CNS.
- MeSH
- embryo nesavčí metabolismus MeSH
- genové regulační sítě MeSH
- homeodoménové proteiny genetika metabolismus MeSH
- mezencefalon embryologie metabolismus MeSH
- Oryzias embryologie genetika MeSH
- rombencefalon embryologie metabolismus MeSH
- rybí proteiny genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Wnt/β-catenin signaling plays an essential role in the retinal pigment epithelium (RPE) determination. Since activity of Pax6 (together with Pax2) is also required for the RPE determination, we investigated a possible genetic interaction between Pax6 and Wnt/β-catenin signaling pathway by analyzing Pax6, β-catenin, and Pax6/β-catenin conditional knockout mice. Although Pax6 inactivation alone had no impact on initial specification determined by the expression of Mitf and Otx2, melanin pigmentation was reduced in the RPE. This suggests that along with Mitf and Otx2, Pax6 is required for the full differentiation of RPE. Reporter gene assays in vitro suggest that hypopigmentation is at least in part due to the direct regulation of genes encoding enzymes involved in melanin synthesis by Pax6, Mitf, and β-catenin. The RPE of a β-catenin/Pax6 double mutant was differentiated into the neural retina; however, the tissue was thinner than that of the conditional β-catenin mutant due to reduced proliferation. Together, our data demonstrate that Pax6 is required for the RPE differentiation by regulating pigmentation and accountable for hyperproliferation in the transdifferentiated RPE. In this context, Pax6 appears to function as a pleiotropic regulator, directing development of ocular tissues in concert with the signaling pathway and, at the same time, regulating expression of structural component of the eye, such as shielding pigment.
- MeSH
- beta-katenin genetika metabolismus MeSH
- homeodoménové proteiny genetika metabolismus MeSH
- myši transgenní MeSH
- myši MeSH
- oční proteiny genetika metabolismus MeSH
- represorové proteiny genetika metabolismus MeSH
- retina cytologie metabolismus MeSH
- retinální pigmentový epitel metabolismus MeSH
- signální dráha Wnt * MeSH
- transdiferenciace buněk MeSH
- transkripční faktory paired box genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
