The Mnx homeobox gene class defined by HB9, MNR2 and amphioxus AmphiMnx.
The HB9 homeobox gene has been cloned from several vertebrates and is implicated in motor neuron differentiation. In the chick, a related gene, MNR2, acts upstream of HB9 in this process. Here we report an amphioxus homologue of these genes and show that it diverged before the gene duplication yielding HB9 and MNR2. AmphiMnx RNA is detected in two irregular punctate stripes along the developing neural tube, comparable to the distribution of 'dorsal compartment' motor neurons, and also in dorsal endoderm and posterior mesoderm. We propose a new homeobox class, Mnx, to include AmphiMnx, HB9, MNR2 and their Drosophila and echinoderm orthologues; we suggest that vertebrate HB9 is renamed Mnx1 and MNR2 be renamed Mnx2.
Ferrier
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DE
School of Animal and Microbial Sciences, The University of Reading, Whiteknights, PO Box 228, Reading, RG6 6AJ, UK.
Brooke
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NM
Panopoulou
G
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Holland
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PW
D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D002816:Chordata, Nonvertebrate / Q000145:classification / Q000235:genetics*; D003001:Cloning, Molecular; D029721:Drosophila Proteins; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000235:genetics*; D018398:Homeodomain Proteins / Q000737:chemistry / Q000145:classification* / Q000235:genetics*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D009626:Terminology as Topic; D014157:Transcription Factors / Q000737:chemistry / Q000145:classification / Q000235:genetics
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C115037:MNR2 protein, vertebrate; D012333:RNA, Messenger; D014157:Transcription Factors; C490005:exex protein, Drosophila