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Dev Biol October 1, 2006; 298 (1): 312-26.

Xenopus Teashirt1 regulates posterior identity in brain and cranial neural crest.

We have isolated two related Xenopus homologues of the homeotic zinc finger protein Teashirt1 (Tsh1), XTsh1a and XTsh1b. While Drosophila teashirt specifies trunk identity in the fly, the developmental relevance of vertebrate Tsh homologues is unknown. XTsh1a/b are expressed in prospective trunk CNS throughout early neurula stages and later in the migrating cranial neural crest (CNC) of the third arch. In postmigratory CNC, XTsh1a/b is uniformly activated in the posterior arches. Gain- and loss-of-function experiments reveal that reduction or increase of XTsh1 levels selectively inhibits specification of the hindbrain and mid/hindbrain boundary in Xenopus embryos. In addition, both overexpression and depletion of XTsh1 interfere with the determination of CNC segment identity. In transplantation assays, ectopic XTsh1a inhibits the routing of posterior, but not of mandibular CNC streams. The loss of function phenotype could be rescued with low amounts either of XTsh1a or murine Tsh3. Our results demonstrate that proper expression of XTsh1 is essential for segmentally restricted gene expression in the posterior brain and CNC and suggest for the first time that teashirt genes act as positional factors also in vertebrate development.

PubMed ID: 16916510
Article link: Dev Biol

Species referenced: Xenopus laevis
Genes referenced: adam33 cdh11 chrd.1 egr2 en2 epha4 fgf8 hoxa2 hoxb9 meis3 nkx3-2 otx2 pax6 pcdh8 sox2 tfap2a tshb tshz1 tshz3 twist1 wnt4
Antibodies: Myc Ab3
Morpholinos: tshz1 MO1

Phenotypes: Xla Wt + tshz1 (Fig 3 E) [+]

Article Images: [+] show captions