Studies

Background and Previous Studies

For many years, the central interest of this laboratory has been the concept and techniques of human gene therapy. These studies have concentrated largely on structural and genetic studies of several virus systems, including the papovavirus polyoma and retroviruses. Toward the goal of developing tools for efficient gene transfer, our laboratory has:

  • developed early methods for DNA sequence determination
  • characterized the human Alu repetitive sequences
  • cloned and sequenced the polyoma genome
  • cloned and sequenced the human hypoxanthine guanine phosphoribosyltransferase (HPRT) gene, mutations of which are responsible for Lesch Nyhan Disease (LND)
  • demonstrated the correction of a disease phenotype by gene transfer
  • developed approaches to gene transfer to the CNS for correction of neurodegenerative disease
  • developed approaches to reverse the neoplastic phenotype by gene transfer of tumor suppressor genes
  • developed methods for modifying the efficiency and tropism of retrovirus vectors by pseudotyping with the G envelope glycoprotein of vesicular stomatitis virus
  • characterized aspects of the molecular basis for the dopamine neurotransmitter defect in Lesch Nyhan Disease (LND) through microarray transcriptional profiling and proteomic studies of HPRT-deficient tissues and cells
  • examined methods for in vitro assembly of virus-like particles and characterized mechanisms for the in vitro assembly of virosomes with enhanced gene transfer properties

Current Studies

Our current studies concentrate on the mechanisms of the dopamine deficit in Lesch Nyhan Disease and on identifying the possible defect in that disorder of differentiation of embryonic stem cells (ES) and neural stem cells to the dopaminergic phenotype. Toward that goal, we are examining the global patterns of gene expression and the proteomes of HPRT-deficient tissues and cells from the HPRT-knockout mouse model of Lesch Nyhan Disease (LND), and we have identified a number of candidate genes whose expression seems to be correlated with the in vitro differentiation of the parent ES cells toward the dopaminergic neuron phenotype. We wish to use these methods to identify the mechanisms underlying the presumed aberrant dopaminergic development in LND and to use this knowledge to design methods for producing dopaminergic neurons in vitro from embryonic stem cells and from neural stem cells. We are continuing our biochemical and functional studies of these genes and their role in the HPRT-deficiency neurological phenotype, and in particular the possibility of aberrant electron transport and mitochondrial dysfunction in the HPRT knockout mouse model of LND. Our laboratory is also pursuing extensive studies on the effects of insulin-like growth factor (IGF-1) and several other growth factors on global gene expression and on the proteomes of cultured myoblasts and on tissues in mice treated with growth factors. We have identified very complex interactions among several gene families that respond to in vivo exposure to IGF-1 and are carrying out genetic and biochemical studies to We are continuing our studies examining the in vitro assembly of virus-like nanoparticles and virosomes in an effort to produce efficient and targeted non-viral gene transfer methods.