Analysis of Hox10 specific peptide motifs in their patterning functions of the axial skeleton
Year: 2009
Type: dissertation
Abstract: Hox genes play a fundamental role in anterior-posterior patterning and are remarkably conserved throughout evolution (Slack et al., 1993). Their products are transcription factors that regulate a specific set of genes with essential functions in development. Although different Hox genes show a notable functional specificity in vivo, they demonstrate a surprisingly low DNA-binding specificity in vitro. Sequence analysis can provide a way to understand how Hox genes achieve their biological specificity (Prince, 2002). Genetic experiments revealed that Hox genes are involved in global patterning processes in the axial skeleton to produce the axial formulae. Hox group 10 genes, in particular, have been shown to repress thoracic rib formation, since their overexpression in the presomitic mesoderm causes a ribless phenotype and their global inactivation resulted in extra ribs (Wellik et al., 2003, Carapuço et al., 2005). Two peptide domains were identified in Hox10 proteins which are conserved among all the Hox 10 members and are absent from all other Hox proteins. One of these is an octapeptide located just N-terminal to the homeodomain. The purpose of this work is to understand the role of this octapeptide in Hox10 protein function. This is being approached by the genesis and functional analysis of transgenic mice expressing mutant Hoxa10 proteins that contain specific deletions or amino acid changes in this domain. In previous transgenic assays, the overexpression of Hoxb9 gene in the presomitic mesoderm did not produce an abnormal axial skeleton phenotype. For this reason, this gene was used to generate chimeric contructs with the Hoxa10 gene. The results obtained show that the removal of the octapeptide is sufficient to block the rib-repressing activity of Hoxa10 when expressed in the presomitic mesoderm. In addition, introduction of this peptide motif, as well as the whole Hoxa10 sequence N-terminal to it, into the Hoxb9 protein produced a partial ribless phenotype. These results indicate that the octapeptide is necessary for the rib-repressing activity of Hoxa10 but it does not seem to be sufficient for this function, at least individually
Author: Isabel Guerreiro
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2231530738