organisation - the Instituto Gulbenkian de Ciência

HOXA10 AND THE EVOLUTION OF THE VERTEBRATE BODY PLAN
One of the functions of Hox genes of the paralogue group 10 during patterning
of the axial skeleton is to block rib formation. This function is essential for the
formation of the rib-less areas of the vertebral column caudal to the ribcage,
such as the lumbar vertebrae. It has been shown that in snakes Hoxa10 is expressed
within the rib-forming area, suggesting that in snakes this gene has lost
the ability to block rib formation. Whether this is an intrinsic property of the
protein itself or due to alterations in the networks downstream to this gene,
remains to be determined. In this project we aim at understanding this problem.
We found that the snake Hoxa10 blocks rib formation when assayed in mouse
embryos. Therefore, the absence of activity in the snake is not due to intrinsic
properties of the protein. We identified a polymorphism in the Hox-responsive
enhancer of Myf5 that renders the enhancer unable to bind Hox proteins. When
assayed in transgenic mice using a BAC reporter approach, we saw that this
polymorphism is functionally relevant, which explains the inability of Hoxa10 to
block rib formation in snakes.
IGC ANNUAL REPORT ‘11
RESEARCH GROUPS
50