High impact information on MSX1

• The apical ectodermal ridge regulates Hox-7 and Hox-8 gene expression in developing chick limb buds [1].
• We show that expression of the two related chicken homeo box genes, Hox-7 and Hox-8, which is widespread in the lateral mesoderm at early stages, becomes restricted to the mesoderm underlying the apical ectodermal ridge as limbs develop [1].
• We found a progressive, lateral expression of Noggin in the embryonic area, and downregulation of Msx1, a BMP4 target gene, with Msx1 expression being ultimately restricted to the most distal embryonic and extra-embryonic somatopleural mesoderm [2].
• Vestibular identity was based on: (1) stereociliary bundle morphology; (2) spacing of hair cells and supporting cells; (3) the presence of otoliths; (4) immunolabeling indicative of vestibular supporting cells; and (5) expression of Msx1, a marker of certain vestibular sensory organs [3].
• The expression of Msx1 and Msx2 genes was maintained under the ridge indicating a good interaction between the interdigital cells, both dissociated and undissociated, and the apical ridge [4].

Biological context of MSX1

• We report the isolation from a chick limb bud cDNA library of several overlapping chicken HOX cDNAs, which on the basis of their nucleotide and deduced amino acid sequences have been identified as corresponding to the chicken cognate of mouse Hox-7 [5].
• Msx1 downregulation thus correlates with the formation of the pterylae, and its maintenance to that of the apterium [2].
• Thus, Dan is required for the normal morphogenesis of the inner ear and, by inhibiting BMP signaling, for the patterning of the transcription factors Nkx5.1 and Msx1 [6].

Anatomical context of MSX1

• Therefore, Hox-7 and Hox-8 depend on a functional ridge for their continued expression in the limb bud and can be induced by it [1].
• In advanced limb buds, Msx1 is also expressed in the proximal mesoderm under the anterior ectoderm [7].

Other interactions of MSX1

• Infection with constitutively active viruses resulted in ectopic expression of Msx1, Msx2 and Fgfr2 throughout the maxillary mesenchyme [8].

Analytical, diagnostic and therapeutic context of MSX1

• In situ hybridization studies revealed the early and wide-spread expression of G-Hox 7 during chick development [9].

References