title: Hoxd13 contribution to the evolution of vertebrate appendages.
abstract: Fossil data suggest that limbs evolved from fish fins by sequential elaboration of their distal endoskeleton, giving rise to the autopod close to the tetrapod origin. This elaboration may have occurred by a simultaneous reduction of the distal ectodermal fold of fish fins. Modulation of 5'Hoxd gene transcription, through tetrapod-specific digit enhancers, has been suggested as a possible evolutionary mechanism involved in these morphological transformations. Here, we overexpress hoxd13a in zebrafish to investigate the impact of increasing 5'Hoxd expression during fin development. This overexpression causes increased proliferation, distal expansion of chondrogenic tissue and finfold reduction. In addition, we also show that the tetrapod-specific 5'Hoxd enhancer CsC promotes similar expression in zebrafish fins and mouse limbs. Our results support the idea that modulation of 5'Hoxd gene expression, by acquisition of novel enhancer elements, offered the substrate for the evolution of fins and the origin of tetrapod limbs.
authors.affiliation: Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía Campus UPO, Ctra. de Utrera km1, E-41013 Seville, Spain.
authors.forename: Renata
authors.initials: R
authors.lastname: Freitas
authors.forename: Carlos
authors.initials: C
authors.lastname: Gómez-Marín
authors.forename: Jonathan Mark
authors.initials: JM
authors.lastname: Wilson
authors.forename: Fernando
authors.initials: F
authors.lastname: Casares
authors.forename: José Luis
authors.initials: JL
authors.lastname: Gómez-Skarmeta
mesh_terms: D058500:Animal Fins / Q000254:growth & development* / Q000502:physiology; D000818:Animals; D005075:Biological Evolution; D049109:Cell Proliferation; D004742:Enhancer Elements, Genetic; D005121:Extremities / Q000254:growth & development / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D015027:Zebrafish / Q000235:genetics* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; C578237:Hoxd13a protein, zebrafish; D014157:Transcription Factors; D029961:Zebrafish Proteins