Complementary homeo protein gradients in developing limb buds.
A new human homeo box-containing gene designated Hox-5.2 was cloned and mapped to human chromosome 2. This homeo box is related in sequence to Abdominal-B, a Drosophila homeotic gene that specifies identity of posterior segments. An antibody probe was made using a human Hox-5.2 fusion protein and was found to stain posterior regions of mouse, chicken, and Xenopus embryos. Unexpectedly, when the distribution of Hox-5.2 antigen was compared with that of X1Hbox 1 antigen, a non-overlapping and mutually exclusive pattern was detected (e.g., in developing limb buds, intestine, and somites). Regions expressing Hox-5.2 do not express X1Hbox 1 protein, and vice versa. Hox-5.2 antigen is detected strongly in developing fore- and hindlimb buds, where it forms a gradient of nuclear protein throughout most of the mesenchyme. This gradient is maximal in distal and posterior regions. Hox-5.2 expression is activated in Xenopus limb regeneration blastemas, as expected for any gene involved in pattern formation. As described previously, a gradient of X1Hbox 1 protein can be detected in the forelimb. The latter gradient has the opposite polarity to that of Hox-5.2. i.e., maximal in anterior and proximal mesoderm. These two opposing gradients (and possibly others) could be involved in determining positional values in developing limb buds.
Oliver
G
G
Department of Biological Chemistry, University of California, School of Medicine, Los Angeles 90024-1737.
Sidell
N
N
Fiske
W
W
Heinzmann
C
C
Mohandas
T
T
Sparkes
R S
RS
De Robertis
E M
EM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002874:Chromosome Mapping; D002889:Chromosomes, Human, Pair 2; D003001:Cloning, Molecular; D004330:Drosophila / Q000235:genetics; D005121:Extremities / Q000196:embryology*; D005801:Genes, Homeobox; D006801:Humans; D007120:Immunochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D005810:Multigene Family; D009693:Nucleic Acid Hybridization; D011993:Recombinant Fusion Proteins; D012038:Regeneration; D014981:Xenopus / Q000196:embryology / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics
D011993:Recombinant Fusion Proteins; D001616:beta-Galactosidase