Teleost HoxD and HoxA genes: comparison with tetrapods and functional evolution of the HOXD complex.
In tetrapods, Hox genes are essential for the proper organization and development of axial structures. Experiments involving Hox gene inactivations have revealed their particularly important functions in the establishment of morphological transitions within metameric series such as the vertebral column. Teleost fish show a much simpler range of axial (trunk or appendicular) morphologies, which prompted us to investigate the nature of the Hox system in these lower vertebrates. Here, we show that fish have a family of Hox genes, very similar in both number and general organization, to that of tetrapods. Expression studies, carried out with HoxD and HoxA genes, showed that all vertebrates use the same general scheme, involving the colinear activation of gene expression in both space and time. Comparisons between tetrapods and fish allowed us to propose a model which accounts for the primary function of this gene family. In this model, a few ancestral Hox genes were involved in the determination of polarity in the digestive tract and were further recruited in more elaborate axial structures.
van der Hoeven
F
F
Department of Zoology and Animal Biology, University of Geneva, Switzerland.
Sordino
P
P
Fraudeau
N
N
Izpisúa-Belmonte
J C
JC
Duboule
D
D
D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D018076:DNA, Complementary / Q000235:genetics; D004064:Digestive System / Q000196:embryology / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000235:genetics; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D017403:In Situ Hybridization; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D015347:RNA Probes; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D014566:Urogenital System / Q000196:embryology / Q000378:metabolism; D014714:Vertebrates / Q000145:classification / Q000196:embryology / Q000235:genetics*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins
D018076:DNA, Complementary; D018398:Homeodomain Proteins; C490944:Hoxd10 protein, mouse; C490939:Hoxd11 protein, mouse; C490943:Hoxd12 protein, mouse; C084118:Hoxd13 protein, mouse; C489520:Hoxd4 protein, mouse; D015347:RNA Probes; D015534:Trans-Activators; D014157:Transcription Factors; D029961:Zebrafish Proteins; C099223:hoxd10a protein, zebrafish; C099221:hoxd11a protein, zebrafish; C099222:hoxd12a protein, zebrafish; C088144:HoxA protein