Hox genes in vertebrate development

R Krumlauf - Cell, 1994 - Elsevier
R Krumlauf
Cell, 1994Elsevier
Organization and Evolution of Hox/HOM-C Complexes The genomic structural and
organizational similarities between vertebrate Hox and Drosophila HOM-C complexes
provided compelling evidence that the Hox/HOM-C clusters arose by duplication and
divergence from a common ancestral cluster that was speculated to be conserved in an
even broader range of animal species (reviewed by Akam, 1989; Scott et al., 1989; Kessel
and Gruss, 1990; Boncinelli et al., 1991; Duboule, 1992; Krumlauf, 1992; McGinnis and …
Organization and Evolution of Hox/HOM-C Complexes The genomic structural and organizational similarities between vertebrate Hox and Drosophila HOM-C complexes provided compelling evidence that the Hox/HOM-C clusters arose by duplication and divergence from a common ancestral cluster that was speculated to be conserved in an even broader range of animal species (reviewed by Akam, 1989; Scott et al., 1989; Kessel and Gruss, 1990; Boncinelli et al., 1991; Duboule, 1992; Krumlauf, 1992; McGinnis and Krumlauf, 1992; see also review by Kenyon, 1994 [this issue of Ce//)). Initially, there was some difficulty in defining the nature of a primordial complex (s), because several features of HOM-C are not shared with Hox clusters. For example, in Drosophila the HOM-C complex is comprised of two separate clusters, bithorax (BX-C; Lewis, 1978) and Antennapedia (An@) complex (Kaufman et al., 1980, 1990), and also contains interspersed genes encoding an immunoglobulin-related protein (amalgam), a cuticle protein, the bicoid maternal-effect homeobox gene, and two zen (zl and 22) homeobox genes involved in dorsoventral patterning (Kaufman et al., 1990). However, the presence of a single Hox/HOM cluster in the red flour beetle Tribolium castaneum (Beeman et al., 1989), the nematode Caenorhabditis elegans (Kenyon and Wang, 1991; Salser and Kenyon, 1994), the crustacean Artemia (Averof and Akam, 1993), and some primitive chordates (Pendleton et al., 1993; Holland et al., 1994) is most consistent with the concept of a single ancestral cluster, paradoxically of a type more related to the vertebrate Hox clusters than Drosophila HOM-C, on which we have historically based so much of our understanding of homeotic complexes. While the data are still emerging from polymerase chain reaction-based screens and genomic cloning (Holland et al., 1992, 1994; Pendleton et al., 1993) it appears that the origins of multiple Hox clusters within a species is a property associated with the evolution of primitive vertebrates.
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