Wong K et al. (2002), Retina dorsal/ventral patterning by Xenopus TBX3.

XB-ART-7810

Biochem Biophys Res Commun 2002 Jan 18;2902:737-42. doi: 10.1006/bbrc.2001.6266.

Show Gene links Show Anatomy links

Retina dorsal/ventral patterning by Xenopus TBX3.

Wong K , Peng Y , Kung HF , He ML .

???displayArticle.abstract???
Although it is well known that patterning in the retina of vertebrates is essential for retina formation and for the retinotopic projection of axons in the embryo, knowledge of molecular and cellular mechanisms of retina patterning is limited. We have previously identified the Xenopus Tbx3 gene (XTbx3) which is expressed in the dorsal retina but not in the ventral retina in Xenopus embryos [H. Li, C. Tierney, L. Wen, J. Y. Wu, and Y. Rao (1997) Development 124, 603-615; M.-L. He, L. Wen, C. E. Campbell, J. Y. Wu, and Y. Rao (1999) Proc. Natl. Acad. Sci. USA 96, 10212-10217]. Dosage-sensitive phenotypes in humans suggest that the manipulation of the amount and location of its products could be informative for understanding its normal function. Here we report that ectopic expression of Tbx3 by mRNA injection suppressed formation of the ventral retina. Furthermore, Tbx3 injection led to inhibition of molecular markers for the ventral retina including Pax-2 and netrin, indicating that Tbx3 plays an important role in retina dorsal/ventral patterning in vertebrates by inhibition of gene expression for ventral retina specification.

???displayArticle.pubmedLink??? 11785961
???displayArticle.link??? Biochem Biophys Res Commun

Species referenced: Xenopus laevis
Genes referenced: aoc2 net1 pax2 rax tbx3

???attribute.lit??? ???displayArticles.show???

	FIG. 1. The expression pattern of XTbx3 is colocalized with that of Xrx1 in the Xenopus embryos by in situ hybridization. XTbx3 transcripts are stained in purple and Xrx1 transcripts are stained in red. (A) At st. 13, XTbx3 is colocalized with Xrx1 in anterior neural plate region. (B) At st. 17, XTbx3 transcripts are located in the distinct eye promodia. (C) At st. 20, the expression pattern of Xrx is a band across the anterior neural plate, XTbx3 is expressed in the dorsal lateral region of Xrx1 field. (D) At st. 25, XTbx3 is strong expressed in the dorsal lateral region of xrx1 field. (E) At st. 28, XTbx3 expression is restricted only at dorsal retinal region, while Xrx1 is expressed in the whole eye.
	FIG. 2. Induction of abnormal eye phenotype by over-expression of XTBX3. mRNA encoding XTBX3 was injected into one blastomere and RNA encoding for b-gal was injected in the other blastomere. (A) Dorsal view of st. 34 embryo. Notice the size of wild type eye (left) and a reduced eye (right). (B) Lateral view of WT eye (injected with mRNA encoding for b-gal). (C) Lateral view of (same embryo shown in B) abnormal eye injected with mRNA encoding XTBX3. (D) Embryos at st. 35. mRNA encoding XTBX3-GR was injected into two blastomeres of two-cell stage embryos and the function of XTBX3 was induced by dexamethasone at st. 25. (Up) Embryo injected with mRNA encoding b-gal. (Down) Embryo injected with mRNA encoding TBX3-GR. (E) Section of a st. 35 embryo with injection of mRNA encoding for b-gal in one blastomere and mRNA encoding XTBX3 in the other blastomere at two-cell stage. Comparing with the wild type eye (left), the PRE is lost in the ventral retinal region after injection of Xtbx3 mRNA. (F) b-gal staining showed that b-gal is localized only one side of embryo after injection of mRNA in one blastomere at two cell stage.
	FIG. 3. Overexpression of XTBX3 inhibits the ventral marker expressions. (A) Whole-mount in situ hybridization. The uninjected sides of the Xenopus embryos are showed in the tight column. (B) Section after in situ hybridization with XPax2 probe. (Left) Uninjected Xenopus embryo at st. 25; (right) st. 16 embryo with injection of XTbx3 mRNA in one blastomere at the two-cell stage.