High impact information on XlHbox1

• In these, four position-specific neural markers (engrailed-2, Krox-20, XlHbox 1, and XlHbox 6) were expressed in the ectoderm in the same A-P order as in the embryo [1].
• We show that the promoter of the dorsalizing homeo box gene siamois is a direct target for the beta-catenin/XTcf-3 complex, establishing a link between the Wnt pathway and the activation of genes involved in specifying the dorsal axis [2].
• We describe the cloning and expression of Xnot, a novel homeo box-containing gene expressed primarily in the gastrula organizing region [3].
• The results of these studies are consistent with the hypothesis that maternally derived signals from the Nieuwkoop center function to positively regulate expression of the homeo box gene goosecoid in Spemann organizer cells, leading to a subsequent repression of Xwnt-8 expression in these cells [4].
• We have searched for homeo box-containing genes expressed during gastrulation in Xenopus embryos with the expectation that analysis of the spatial and temporal expression of these genes will lead to greater understanding of the regionalization of the mesoderm [3].

Biological context of XlHbox1

• The Hox-2 locus on chromosome 11 represents one of the major clusters of homeo-box-containing genes in the mouse [5].
• Sequential expression of murine homeo box genes during F9 EC cell differentiation [6].
• A cDNA clone (p52) that contains all the protein-coding region from the maternally expressed XlHbox 2 locus of the frog Xenopus laevis has been isolated and sequenced [7].
• We sought to determine whether the expression of the homeobox protein/s during mouse embryonic development was specific to beta cells or, alternatively, whether XlHbox 8/STF-1 protein/s were initially expressed by multipotential precursors and only later became restricted to the insulin-containing cells [8].
• A similar transient expression of XlHbox-1 gene product during myogenesis occurs during muscle differentiation in the limb bud and during differentiation of visceral smooth muscles from the lateral plate mesoderm [9].

Anatomical context of XlHbox1

• Endonucleolytic cleavage of a maternal homeo box mRNA in Xenopus oocytes [10].
• XlHbox 8: a novel Xenopus homeo protein restricted to a narrow band of endoderm [11].
• The XlHbox 8 homeodomain protein of Xenopus and STF-1, its mammalian homolog, are selectively expressed by beta cells of adult mouse pancreatic islets, where they are likely to regulate insulin expression [8].
• When mesoderm-free vegetal explants (VEs) from early blastula stage embryos are cultured in isolation, XlHbox 8 expression develops autonomously in the dorsal region, strongly suggesting that endodermal region-specific determination occurs before MBT [12].

Other interactions of XlHbox1

• The LIM domain-containing homeo box gene Xlim-1 is expressed specifically in the organizer region of Xenopus gastrula embryos [13].

Analytical, diagnostic and therapeutic context of XlHbox1

• Studies on XlHbox 1 function show that the region common to the long and short proteins has a sequence-specific DNA-binding activity, and that microinjection of specific antibodies into embryos results in the loss of structures derived from cells normally expressing XlHbox 1 [14].
• We have studied by immunohistofluorescence and confocal microscopy the localization of the XlHbox-1 protein, the product of a Xenopus class 1 homeobox gene corresponding to the human HOX 3C, during the development of Xenopus laevis mesodermal derivatives [9].

References