Sidney M. Gospe, M.D., Ph.D. - US grants

This application is being submitted to the ADAMHA Small Grant Program. The goal of this research is to establish an animal model of toluene embryopathy, a recently characterized clinical teratogenic syndrome described in offspring of women with a history of chronic toluene abuse. Clinically, this condition resembles fetal alcohol syndrome (FAS). Animal research has demonstrated that inhaled toluene is readily transferred to the fetus and to the developing central nervous system (CNS), however, specific toluene-induced gross malformations of the developing CNS have not been noted. Neither the microscopic neuropathologic effects nor the CNS biochemical consequences of prenatal toluene exposure have been studied. Aberrations of neuronal migration and other forms of cerebral dysgenesis have been observed in children with FAS. These CNS anatomic features, together with biochemical alterations, have been noted in animal models of FAS. Similar histologic and biochemical features, therefore, could underlie the clinical neurologic and behavioral impairment of toluene embryopathy. This hypothesis will be tested by studying neuronal generation and migration, the microscopic neuropathology, and the biochemistry of brain tissue from rats exposed to toluene in utero. Pregnant rats will be exposed to toluene by gavage administration on days 6 - 21 of gestation; maternal toxicity will be monitored, and fetotoxicity and general teratogenicity of toluene will be determined. Brain sections will be examined for pathologic changes for evidence of abnormal neuronal migration. Neuronal generation and migration will be evaluated further with 3H-thymidine autoradiography. Biochemical analysis to determine brain tissue ornithine decarboxylase activity and protein, DNA, and cholesterol content will be performed. Biochemical indices of brain growth and development will be calculated and the effects of prenatal toluene exposure on these parameters will be determined.

Candidate: The candidate is a MD/PhD-trained clinician-scientist and board-eligible ophthalmologist currently completing a neuro-ophthalmology fellowship, who will be promoted to Duke Eye Center faculty in July, 2017. His research interest relates to pathobiology and drug discovery in mitochondrial optic neuropathies, a class of blinding disease for which effective therapy does not currently exist. Career Development Plan: The candidate proposes to create a mouse model of retinal ganglion cell (RGC)-specific complex I deficiency, predicted to cause particularly rapid and severe RGC degeneration. The proposed research will allow the candidate to gain experience in animal modeling of human disease, biochemical and histological assays of mitochondrial dysfunction, and retinal electrophysiology. Animal models, reagents, and insights developed in this project will serve as the basis for an R01 proposal to be submitted by the candidate in his final year of K08 support. Specific didactic courses in neurobiology, drug discovery and translation, toxicology, and biostatistics, as well as departmental research seminars and advanced training in responsible conduct of research will be obtained during his K08 tenure, and the candidate will present his findings regularly at national meetings and submit his work for publication. Environment: The candidate?s mentoring team consists of accomplished faculty whose wide range of expertise will be utilized in specific components of the research plan. He will also benefit from informal mentorship and interactions with world-class clinical and research faculty in the Duke Eye Center and from immersion in the dynamic intellectual environment and career development resources available throughout the university. Significant departmental commitment and deep personal investment by the mentoring team will ensure that the candidate is well positioned to transition to an independent R01-funded investigator. Research: Mitochondrial dysfunction frequently results in vision loss from optic neuropathy that reflects the particular sensitivity of RGCs to impaired aerobic metabolism and increased oxidative stress. This application?s central hypotheses are that (1) mitochondria-related RGC degeneration is a cell-autonomous process and (2) RGC metabolism may therefore be manipulated to make these cells less susceptible to mitochondrial insults. Aim 1 will test the first hypothesis by creating a mouse with severe deficiency of mitochondrial complex I specifically in RGCs via conditional knockout of the subunit ndufs4. RGCs in these mice will be assessed for histological, electrophysiological, and metabolic abnormalities. Aim 2 tests the second hypothesis by augmenting Hif-1? signaling with complementary genetic and pharmacologic approaches and assessing whether biasing RGC metabolism toward anaerobic glycolysis makes RGCs resistant to mitochondrial dysfunction and could represent a viable therapeutic strategy.