Positions and Employment
The vertebrate olfactory system is an extremely plastic neurobiological substrate that provides a platform from which one can address questions relating to sensory transduction, neuronal ontogeny, plasticity, regeneration and transynaptic regulation of gene expression. One of the major goals of my laboratory is to identify and characterize the molecular mechanisms responsible for regulating olfactory neuron gene expression, and to learn how they contribute to the formation, organization and function of this critical chemosensory system.
We use a multidisciplinary strategy emphasizing biochemical and molecular biological approaches. Promoter motifs involved in regulating olfactory neuron gene expression have been characterized in vitro by gel-shift and footprinting analyses and in vivo by the generation of transgenic mice using truncated and mutated promoter constructs. This latter approach has been used to selectively engineer heterologous gene expression in olfactory neurons.
Primary olfactory neurons are constantly being replaced from a population of precursor cells in the nasal neuroepithelium. These new neurons reinnervate the olfactory bulb. Two questions that arise as a result of this observations are 1) Is reinnervation topographically correct? 2) What are the mechanisms that participate in this process? To address the former we have used transgenic mice expressing the lacZ gene in a subset of cells to demonstrate, for the first time, that reinnervation of the bulb after deafferentation is topographically correct. To address the second question we have begun to characterize the patterns of expression during development and in response to lesion of the BMP family of cytokines and their modulators (noggin, chordin, follistatin and tolloid). These molecules are differentially expressed in various neuronal populations in the olfactory system in spatial and temporal patterns that implies that they participate in development and reorganization of this system. these processes. This is a new and active direction for the laboratory.
An ongoing question in the lab is the function of OMP, a novel phylogenetically conserved, cytoplasmic protein. To this end we have created "knock-out" mice. These mice are superficially normal, but manifest reduced olfactory neural activity. This is evident both electrophysiologically and behaviorally. These observations imply that OMP is a novel regulator of olfactory signal detection/transduction. To address this we are utilizing electrophysiological, behavioral and biochemical approaches. We have "rescued" the electrophysiological phenotype by transfection of olfactory neurons with OMP expressing adenovirus. Attempts to do the same for the behavioral deficit are underway. Biochemical approaches to this problem include the use of 1)solution NMR to determine the 3-D structure of OMP, 2)biochemical studies of protein-protein interaction and 3) phage display to identify and characterize the molecular components responsible for the phenotype observed.
Lab Techniques and Equipment:
We utilize a range of biochemical, molecular and anatomical techniques in the lab such as 1) protein characterization by isolation, western blotting and cross linking, 2) cDNA cloning, RT-PCR, phage display and protein expression and 3) in situ hybridization, histology and immunocytochemistry. Behavioral and electrophysiological studies are by collaboration.
Grants and Contracts: