Phylogenetic analysis of Hoxa 11 sequences reveals absence of transposable elements, conservation of transcription factor binding sites, and suggests antisense coding function.
Nine thousand and eighty-eight base pairs of the chicken Hoxa 11 gene, including 8470 bases 5' of the translation start site were sequenced, and the characteristics of the upstream sequence investigated. Consistent with previous findings that middle repetitive elements are rare in the HoxA cluster, no repetitive elements were found other than simple oligonucleotide repeats. Multiple and pairwise alignments of the chicken upstream sequence with its human and mouse orthologs revealed multiple regions of 80% or higher homology across species. For the chicken, these regions were separated by sequences with no significant homology to human, mouse, or in most cases any other Genbank sequences. Selective clustering of transcription factor binding motifs was found to occur within the conserved homologous regions, suggesting evolutionary conservation of critical regulatory sequences. Of particular interest, seven conserved Cdx binding sites were found in the Hoxa 11 promoter, suggesting regulation by a non-clustered Caudal homeobox gene. Previous analysis of the mouse and human Hoxa 11 genes found a conserved antisense transcript, of unknown function. The chicken Hoxa 11 antisense strand included a conserved open reading frame capable of encoding 168 amino acids. Comparison of this region in mouse and chicken showed seven insertion/deletions, with each a multiple of three bases, thereby preserving open reading frame.
Division of Developmental Biology, Children's Hospital Medical Center, TCHRF 3007, 3333 Burnet Ave., Cincinnati, OH 45229, USA.
Diane M
DM
Bodenmiller
C Stuart
CS
Baxter
David V
DV
Hansen
S Steven
SS
Potter
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002645:Chickens; D017124:Conserved Sequence; D004251:DNA Transposable Elements; D016373:DNA, Antisense / Q000502:physiology*; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000235:genetics*; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D004251:DNA Transposable Elements; D016373:DNA, Antisense; D018398:Homeodomain Proteins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; C487378:Tlx1 protein, mouse; C071250:TLX1 protein, human