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Changes in Hox genes’ structure and function during the evolution of the squamate body plan

2010; Nature Portfolio; Volume: 464; Issue: 7285 Linguagem: Inglês

10.1038/nature08789

1476-4687

Nicolas Di‐Poï, Juan I. Montoya‐Burgos, Hilary Miller, Olivier Pourquié, Michel C. Milinkovitch, Denis Duboule,

Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities

Hox genes play a central role in the specification of structures along the body axis of all animals, and modifications in Hox expression patterns parallel the diversity of the vertebrate body plan. A study of Hox organization in squamate reptiles — the lizards and snakes — shows that the Hox clusters have unexpectedly accumulated transposable elements, reflecting extensive genomic rearrangements of coding and non-coding regulatory regions. Comparative expression analyses between two species showing different axial skeletons, the corn snake and the whiptail lizard, reveals major alterations in Hox13 and Hox10 expression coincident with the expansion of the caudal and thoracic regions of the developing snake embryo. The alteration of Hox cluster structure and function may therefore reflect the extensive morphological radiation observed in this group. The organization of Hox clusters in several different reptiles is investigated, showing that the Hox clusters in squamates — lizards and snakes — have unexpectedly accumulated transposable elements, reflecting extensive genomic rearrangements of coding and non coding regulatory regions. Comparative expression analyses between two species showing different axial skeletons, the corn snake and the whiptail lizard, revealed major alterations in Hox13 and Hox10 expression features during snake somitogenesis, in line with the expansion of both caudal and thoracic regions. Hox genes are central to the specification of structures along the anterior–posterior body axis1,2, and modifications in their expression have paralleled the emergence of diversity in vertebrate body plans3,4. Here we describe the genomic organization of Hox clusters in different reptiles and show that squamates have accumulated unusually large numbers of transposable elements at these loci5, reflecting extensive genomic rearrangements of coding and non-coding regulatory regions. Comparative expression analyses between two species showing different axial skeletons, the corn snake and the whiptail lizard, revealed major alterations in Hox13 and Hox10 expression features during snake somitogenesis, in line with the expansion of both caudal and thoracic regions. Variations in both protein sequences and regulatory modalities of posterior Hox genes suggest how this genetic system has dealt with its intrinsic collinear constraint to accompany the substantial morphological radiation observed in this group.