NICOTINAMIDE MONONUCLEOTIDE ADENYLYLTRANSFERASES IN NEONATAL HYPOXIA-ISCHEMIA

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DESCRIPTION (provided by applicant): The goal of this Mentored Career Development Award is to facilitate Dr. Rafael Galindo's transition to independence as a physician-scientist studying the neurobiological mechanisms of neuronal death in injured developing neurons. The proposed experiments will be conducted under the mentorship of Dr. David Holtzman, and they will examine the potential neuroprotective role of a family of three NAD+ metabolizing enzymes, known as nicotinamide mononucleotide adenylyltransferases (NMNATs), in neonatal brain hypoxia- ischemia (H-I). This form of injury is the most common cause of death in the newborn period and accounts for a significant portion of the chronic neurological conditions attributed to brain injury in the perinatal period. Despite its high prevalence, there are only limited effective therapies available for newborns exposed to H-I. This lack of effective clinical intervention is attributed, in part, to our incomplete understanding of the neurobiological mechanisms and molecules that regulate neuronal death pathways in the healthy and injured developing brain. NMNATs are molecules that have been shown to have strong neuroprotective properties and are likely importantly involved in the neurodegenerative mechanisms of various central and peripheral neurological diseases. Nevertheless, the neuroprotective properties of NMNATs in the central nervous system have not yet been well studied, and its potential role in the injured and healthy immature brain is even less well understood. The goal of this project is to test the hypothesis that endogenous and exogenous NMNAT proteins protect developing neurons from the effects of H-I by increasing the calcium buffering capacity of mitochondria. In order to test this hypothesis, this proposal will utilized various biochemical, immunological, molecular and genetic techniques to assess the role of these proteins in injured developing neurons through the following aims: 1) To characterize the expression and role of endogenous NMNATs in cell death following neonatal H-I utilizing immunochemical and bimolecular methods of NMNAT gene expression and employing gene knock-down techniques. 2) To assess the neuroprotective role of exogenous NMNAT 1, 2 and 3 in the neonatal brain following H-I using transgenic animal models and gene transduction systems. 3) Investigate the neuroprotective mechanism of NMNAT(s) in the neonatal brain employing biochemical and bioluminescent techniques to examine mitochondrial physiology in over- and under-expressing NMNAT in vitro models of H-I and excitotoxicity. The proposed experiments will likely shed new light in our understanding of the biological processes that regulate neuronal cell death in the developing newborn brain. Furthermore, this knowledge may ultimately lead to identifying novel therapeutic targets for the treatment and prevention of the neurological consequences attributed to brain injury in the newborn.