Regulación de la expresión de los genes homeóticos de "Drosophila" por genes del grupo "Polycomb" y del grupo "trithorax"

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular, Fecha de lectura 10-06-2004The homeotic genes specifi the diversification of the morphological pathways in most of the animals, including Drosophila melanogaster. Their expression is restricted to specific cellular domains along the anterior-posterior axis, which generates their activation and repression domains. The mechanisms of maintenance of the "on" and "off" transcriptional state throughout development mediated by the Polycomb (PcG) and trithorax group (trxG) of genes has been the subject of this Thesis. Al1 the so far experimental evidence supports the proposition that the PcG and trxG proteins iünction to maintain the expression of the homeotic genes through the generation of multimenc PcG and trxG protein complexes. This thesis has first studied the DNA sequences that are being recognized by the PcG and trxG proteins to repress and or activate the homeotic genes transcnption. Second, it has also been studied the role of the GAGA factor, a trxG protein, in the regulation of the homeotic genes expression throughout development. Third, and finally, to get insight about the mechanisms of maintenance of homeotic gene expression, it is essential to know the components of the multimenc protein complexes. Recently, the munne RYBP gene has been discovered and proposed to function as a PcG gene. A homologous gene exists in Drosophila and this Thesis has studied its role in the maintenance of homeotic gene expression