DEVELOPMENT AND MIGRATION OF LHRH NEURONS

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My immediate career objective is to continue the transition to molecular developmental neuroscience. My long term goal is to become as familiar with molecular approaches to developmental problems as I am with neuroanatomy and embryology. Expertise in both areas will be useful in evaluating the function of genes in development. Currently, teaching and administrative duties take up a considerable amount of my time. If l received a RCDA, would be relieved of many of these duties. This would free up time that would allow me to receive additional training in molecular techniques. Dr. Thomas Rosenquist, my Departmental Chairman, is very supportive of my application for a RCDA. If I receive this grant, he has indicated that he will provide funds for a post-doctoral fellow with experience in molecular biology to work in my laboratory. The department of Cell Biology and Anatomy has recently formed a Molecular Biology Core Facility. This facility will contain many of the resources I need to complete the proposed experiments. In addition, l will also utilize the Monoclonal Antibody Facility at the University of Nebraska Medical Center. In this RCDA proposal, we plan to take advantage of our familiarity with LHRH neuronal migration and the development of the olfactory system in the chick to examine how LHRH neurons enter the brain during development. Recent studies have demonstrated that X-linked Kallmann's disease is due to a failure of the olfactory nerve to enter the telencephalon and LHRH neurons to migrate into the brain. The gene involved in this disease, KAL, may be the first human gene identified as having a role in neuronal migration. We have three specific aims: Aim l. The role of the olfactory nerve in LHRH neuronal migration. In this specific aim we seek to answer two questions. First, do LHRH neurons migrate along a transitory extension of the olfactory nerve? Second, are LHRH neurons associated with the same axons in the olfactory nerve throughout their migration? We hope to answer these questions by labeling olfactory nerve axons at different stages of development. Aim Il. Spatial- temporal distribution of the KAL protein at the light and electron microscopic levels. As there appears to be a spatial-temporal mismatch between KAL message and LHRH neuronal migration, it is crucial to examine the distribution of KAL protein during development. We will use double-label immunocytochemistry to determine whether LHRH neuronal migration is correlated with KAL protein expression. Aim III. Function of the KAL protein. Since mutations in KAL disrupt LHRH neuronal migration and olfactory nerve pathfinding, there is good reason to believe that KAL is involved in these events. However, the mechanism for these effects is not known. We will use tissue culture, ablation, and antibody and peptide blocking experiments to determine the role of KAL in the development of the nervous system. The unique opportunities available in the chick system, and the fact that the complete coding sequence of the mRNA for KAL is available in the chick, makes this the best animal model system for Kallmann's syndrome. In addition, these studies will allow us to dissect mechanisms for neuronal migration and axon pathfinding that may be applicable to other regions of the developing nervous system.