Candidate Joseph Dougherty, Ph.D.. was an HHMI predoctoral fellow and a 2005 Neuroscience graduate from University of California, Los Angeles, where he trained with Dr. Daniel Geschwind. His dissertation entailed gene expression profiling to identify neural stem and progenitor cell genes, followed by anatomical and functional studies of candidate genes. For three years, he has worked as a postdoctoral associate in the laboratory of Dr. Nathaniel Heintz developing methods for in vivo studies of genetically defined cell types, culminating in a broad survey of translational profiles across the CNS1. Joseph now has extensive training in cellular and molecular neuroscience, BAC transgenesis, neuroanatomy, gene expression profiling, and bioinformatics. To prepare for a career as an independent scientist studying the contributions of specific cell types to human neurogenetics disorders, he will spend the next two years learning human statistical genetics and mouse behavioral research. Training will be provided by an advisory committee of faculty whose work bridges human disease and neuroscience, as well as formal coursework and workshops, close collaborations with human genetics researchers, and, most importantly, the experience gained by the pursuit of the aims outlined below. Environment The Rockefeller University is an ideal incubator for young scientists. It has world-renowned faculty in a variety of disciplines, the scientific facilities of a major institution, yet it maintains the efficiency and ease of collaboration found on a small campus. The laboratory of Dr. Nathaniel Heintz is similarly well equipped. The laboratory has all of the necessary equipment for molecular, cellular, anatomical and behavioral neuroscience studies. With the nearby pool of expertise from the GENSAT project, and a solid core in the laboratory of talented colleagues and skilled technical support, the laboratory is a world leader in targeting specific cell types in mice. Finally, Dr. Heintz is a highly innovative scientist with a solid record in mentoring young scientists preparing for independent positions. Research Proposal The nervous system is composed of hundreds of distinct cell types, each with unique morphology, connections, and gene expression. Importantly, perturbations in rare cell types, composing a small fraction of the entire brain, can result in devastating disorders afflicting the entire organism. For many disorders, the circuits and cells underlying the disease are unknown. Recent technical advances have driven an ongoing explosion of genome wide studies attempting to associate genetic polymorphisms with disorders of the CNS. Likewise, other technologies have dramatically reduced the cost of resequencing candidate genes to identify putative mutations. Still, the understanding of how polymorphisms in various genes can lead to a common disease is generally not understood. We have recently developed a methodology, Translating Ribosome Affinity Purification (TRAP), to isolate the complete suite of genes being employed by any particular cell type in the mammalian brain2. TRAP is sensitive and robust, as demonstrated in an initial survey of twenty four populations across the mouse brain1. Here, I propose to apply this methodology to help bridge the gap between a polymorphism in a gene and a symptom in a disorder with two general approaches. First, when a cell type is suspected of being selectively vulnerable in a disorder, we can identify the suite of genes that are employed selectively in that particular cell type as potential disease candidates. Second, when there are many candidate genes known, we can analyze our cell- type specific translational profiles to determine if these various genes implicate a common cell type or circuit. To test the first approach, we have isolated the complete translational profile of the serotonergic neurons of the raphe nuclei. As dysregulation of the serotonergic system has long been suspected to be involved in autism3, we have tested the association between the serotonergic genes and autism in a large multiplex patient population4. We discovered associations in two genes. Preliminary sequencing studies in the first gene have identified a premature stop codon in patient DNA. The initial aims of the current proposal are first to confirm these findings in independent samples, and then to recapitulate this genetic mutation in a conditional manner in the mouse to test for features of autism following cell-specific and germline deletions. The long-term aims of this proposal are designed to test the general utility of this cell-oriented approach to human neurogenetics.
These aims i nclude the generation of additional TRAP lines for cell types suspected in CNS disorders, and the development of methodology to implicate novel cell types for those disorders in which the cells and circuits are poorly understood, based on the specific translation of previously identified candidate genes. The cellular etiology of CNS disorders is an area much in need of elucidation. Even if patients have a variety of different underlying genetic causes for a disease, if a common cellular mechanism can be identified, that provides a target for treatment strategies. The approach proposed here may have the potential to provide those cellular targets for treatments.
The cellular etiology of CNS disorders is an area much in need of elucidation. Even if patients have a variety of different underlying genetic causes for a disease, if a common cellular mechanism can be identified, that provides a target for treatment strategies. The approach proposed here has the potential to provide those cellular targets for treatments.
| Xu, Xiaoxiao; Nehorai, Arye; Dougherty, Joseph (2013) Cell Type Specific Analysis of Human Brain Transcriptome Data to Predict Alterations in Cellular Composition. Syst Biomed (Austin) 1:151-160 |
| Dougherty, Joseph D; Zhang, Juliet; Feng, Huifen et al. (2012) Mouse transgenesis in a single locus with independent regulation for multiple fluorophores. PLoS One 7:e40511 |
