High impact information on Xhox3

• Our findings suggest that Xhox3 is involved in establishing anterior-posterior cell identities during pattern formation of the axial mesoderm in early embryonic development [1].
• Although RA changes the character of mesoderm, it does not seem to affect mesodermal induction by PGFs or the levels of Xhox3 mRNA induced in the mesoderm by PGFs [2].
• We have previously shown that expression of Xbra alone in animal caps is sufficient to specify ventral mesoderm which expresses Xhox3 and low levels of muscle-specific actin [3].
• We show that p53 functionally and physically interacts with the activin and bone morphogenetic protein pathways to directly induce the expression of the homeobox genes Xhox3 and Mix.1/2 [4].
• Moreover, the homeobox gene Xhox3, a critical determinant of posterior development, is also directly regulated by Gli2 [5].

Biological context of Xhox3

• Bimodal and graded expression of the Xenopus homeobox gene Xhox3 during embryonic development [6].
• In late tadpole stages, Xhox3 is only expressed in the mid/hindbrain area and can therefore be considered a marker of anterior neural development [7].
• We further find that (1) Xvents act as transcriptional repressors, (2) Xvents function in an additive fashion and (3) a surprising number of genes are able to rescue dominant-negative Xvent phenotypes including Bmp-4, Smad-1 and wild-type Xvents and Xhox3, but not Xwnt-8 [8].
• Intestinal fatty acid binding protein (IFABP) is expressed only in the anterior small intestine, and the even-skipped homeobox gene Xhox3 is expressed in the most posterior part of the gut, the proctodeum [9].

Anatomical context of Xhox3

• During the early period of Xhox3 expression, the gastrula and neurula stages, transcripts are found in a graded fashion along the anteroposterior (A-P) axis in the mesoderm and are most concentrated at the posterior pole [6].
• The Xenopus laevis homeobox gene Xhox3 is expressed in the axial mesoderm of gastrula and neurula stage embryos [7].
• Treatment with RA caused a concentration-dependent change in the pattern of expression of Xhox3 and serotonin and resulted in the ectopic appearance of immunoreactive neurons in anterior regions of the CNS, including the forebrain [10].
• In situ hybridization analyses of exogastrulated embryos show that Xhox3 is expressed in the apical ectoderm of total exogastrulae, a region that develops in the absence of anterior axial mesoderm [7].
• In situ hybridization analysis of the expression of Xhox3 in neural tissue shows that it is restricted within the neural tube and the cranial neural crest during the tailbud-early tadpole stages [7].

Associations of Xhox3 with chemical compounds

• Evidence for the conservation of the NH2 terminal region of the Xhox3 protein in frogs and fish is provided by the detection of a nuclear Xhox3-like protein in 24 h zebrafish embryos located in posterior mesoderm tissue [11].

Regulatory relationships of Xhox3

• Combined expression of Xwnt3a and active Notch in animal cap explants is sufficient to induce Xhox3, provoke elongation and form neural tubes [12].

Other interactions of Xhox3

• A Xenopus laevis homeobox gene, Xhox3, has been isolated using the homeobox of the Drosophila pair-rule gene even skipped as a hybridization probe [6].

Analytical, diagnostic and therapeutic context of Xhox3

• Previous results in Xenopus embryo research and the data presented here support the conservation of an A-P patterning mechanism involving the Xhox3 gene [11].
• The widespread expression of the Xenopus homeobox gene Xhox3 in zebrafish was performed by microinjection of synthetic Xhox3 mRNA into uncleaved fertilized eggs and resulted in embryos displaying varying degrees of anterior-posterior (A-P) axis disruption [11].

References