The murine Hoxc cluster contains five neighboring AbdB-related Hox genes that show unique spatially coordinated expression in posterior embryonic subregions.
A common feature of the murine Abdominal B (AbdB) -related Hox genes, located in the 5' regions of the four Hox clusters, appears to be a function in patterning the developing limb. As a prerequisite for studying the role of the AbdB-related Hoxc genes during limb development, we have isolated and mapped the three predicted AbdB-related Hoxc-11, -12, and -13 loci, thus defining the 5' end of the Hoxc cluster. Sequence comparisons based on the homeobox sequences of presumably all murine AbdB-related Hox genes strongly support the concept of a two step process in their evolution. As expected, Hoxc-11, -12 and -13 exhibit nested and extremely posteriorly restricted expression domains, whose anterior boundaries reflect their map positions, in accordance with the colinearity rule. A limited comparison of the primary expression domains of all five AbdB-related Hoxc genes in the developing hindlimb revealed nested and increasingly restricted domains of expression in the mesenchyme for only Hoxc-9, -10 and -11. However, separate localized expression was detected for Hoxc-9, -10, -11, -12 and possibly -13 in distal epidermal regions of the developing hind- and forelimb, whereas no expression of any of the five genes was observed in mesenchymal tissues of the developing forelimb. These data suggest a specific role for the AbdB-related Hoxc genes in patterning the hindlimb and pelvic girdle, which is separate from a second role relevant for both hind- and forelimb development.
Department of Medicine, Medical University of South Carolina, Charleston 29425.
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Peterson
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Papenbrock
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Davda
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Awgulewitsch
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004622:Embryo, Mammalian / Q000378:metabolism; D005121:Extremities / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005801:Genes, Homeobox; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family