Laboratory of Molecular Neurobiology

The central theme of the research in this laboratory involves the use of molecular biology and proteomics to study the nervous system. Specifically, the laboratory is actively engaged in (a) understanding structure/ function relationships in the biogenic amine (dopamine, norepinephrine, epinephrine, and serotonin) biosynthetic enzymes (tyrosine hydroxylase and tryptophan hydroxylase); (b) using functional genomic (DNA array, RT-PCR) and proteomic (2-D PAGE, mass spectrometry) technologies to better understand genomic and epigenetic factors in substance abuse (cocaine, alcohol) and neurodegeneration; and (c) stem cell development and characterization.

The rate-limiting enzyme in catecholamine biosynthesis is tyrosine hydroxylase (TH), while the rate-limiting enzyme in serotonin biosynthesis is tryptophan hydroxylase (TPH). In one aspect of our work, full-length cDNA clones for TH and TPH are modified by site-directed mutagenesis and the mutant proteins expressed in bacteria. The recombinant enzymes are then characterized in terms of their structure, activity and regulation. The results of these studies provide insights into how these pivotal enzymes function in health and disease (including the functional consequences of human single nucleotide polymorphisms). A central premise of our second research area is that chronic drug abuse creates an epigenetic imprint - a stable environmental alteration in the pattern of mRNA and protein expression - that contributes to such clinical observations as physical dependence, psychological addiction, withdrawal and relapse liability. Moreover, some individuals can inherit such a pattern of gene expression creating an increased risk of abuse liability. While this laboratory has characterized environmental effects on gene expression for many years, we have more recently adopted high throughput methods (multiplex DNA microarrays and mass spectrometry) to identify those mRNAs and proteins that are engaged in the polygenic problem of substance abuse. In a third aspect of our work, molecular tools have been brought to bear on a number of problems related to neurodegenerative disease. These have included: genotyping genetic factors related to Alzheimer's Disease (ApoE and presenilin); investigating the role of dopamine quinone production and covalent modification in dopamine-mediated neurotoxicity (Parkinson's Disease); and examining the environmental neurotoxicology associated with manganese exposure.

New efforts within the laboratory include the study of human embryonic and adult stem cells. We were part of the research team that demonstrated the ability to generate pluripotent embryonic stem cells via parthenogenetic activation of oocytes in non-human primates. This ability to create ES cells from non-fertilized, self-limiting, and non-viable embryos may provide ethical alternatives to the use of fertilized embryos in therapeutic cloning applications. Proteomic and functional genomic tools are being used to profile those genes and gene products that contribute to "stemness", as well as stem cell differentiation (both non-human primate and human embryonic stem cells).