The two objectives of this proposal have been designed to dissect the complex phenotype of the EphA4 knock-out on the nervous system using innovative transgenic mouse strategies.
1) Analysis, in vivo, of the intracellular mechanisms whereby EphA4 regulates axon guidance during nervous system development. The study will be accomplished by a knock - in strategy sing different EphA4 mutants, some of which will be generated during this proposal. Primary cultures of cortical or hippocampal neurons from these mutant mice will be used to perform an exhaustive and comparative analysis of the intracellular signaling pathways activated by each of the EphA4 mutant receptors. These results will be correlated with the in vivo axon guidance defects observed in each mutant to evaluate the relevance of specific intracellular pathways activated by EphA4 on axonal outgrowth.
2) Analysis of the role of EphA4 in synaptic plasticity and learning in the adult animal. This second part of the project will be accomplished by a conditional knockout strategy in which the expression of EphA4 will be specifically deleted from the forebrain of adult animals. This strategy avoids the locomotors deficiencies that appear during development of EphA4 knock-out mice that could affect behavioral tests. This study aims to provide important information to the poorly studied role of the Eph/ephrin system in the physiology of the adult brain.