Oxidative stress is a critical mediator of the injury response after neonatal hypoxia ischemia. Evidence suggests that hydrogen peroxide toxicity is related to cell death but a paradox exists such that H2O2 may also be a signaling molecule that is involved in neuroprotection. In particular, H2O2 may be a critical mediator of hypoxic or ischemic preconditioning in the immature brain. We hypothesize that H2O2 serves as a critical signaling molecule for activation of hypoxia inducible factor 1 (HIF1) to promote protection in the brain after neonatal ischemia. To address this hypothesis we will determine the mechanisms by which HIF1 is regulated by H2O2 to generate a cytoprotective response in immature primary neurons from hippocampus and cortex by measuring HIF 1a induction by mRNA and protein levels, DMA binding activity by EMSA and promoter activity. We will measure HIF1a dependent cytoprotective genes and compare to changes in pro- apoptotic genes and their protein targets. We will measure H2O2 and the cellular localization of reactive oxygen species and we will block preconditioning using antisense or knockdown strategies against HIF1. We will study redox-sensitive signaling pathways such as MARK, PI3K/Akt to determine their involvement in hypoxic HIF1 signaling and neuronal protection. We will assess phosphorylation states and use pharmacological inhibitors to determine relevant activities.
The second aim will test how altering glutathione peroxidase activities by overexpression or knockdown will affect hypoxic preconditioning and injury in vitro and in vivo and how this relates to H1F1 activation and redox signaling. We will measure HIF1 activation and H2O2 levels necessary to achieve preconditioning neuroprotection. In the final aim we will determine how modulation of HIF1 activity by genetic deletion, pharmacological stabilization or induction by growth factors affect hypoxic preconditioning and neuronal injury in vivo. We will also test behavioral outcomes in these animals to determine whether this is a functional deficit.

Public Health Relevance

TO PUBLIC HEALTH. Lack of oxygen to the newborn brain is the major cause of lifelong disability in children resulting in mental retardation, epilepsy and cerebral palsy. Understanding pathways for protecting the brain will result in therapeutic avenues for brain recovery.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS033997-13
Application #
7758269
Study Section
Developmental Brain Disorders Study Section (DBD)
Program Officer
Hicks, Ramona R
Project Start
1996-04-01
Project End
2012-01-31
Budget Start
2010-02-01
Budget End
2011-01-31
Support Year
13
Fiscal Year
2010
Total Cost
$302,566
Indirect Cost
Name
University of California San Francisco
Department
Neurology
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
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Larpthaveesarp, Amara; Ferriero, Donna M; Gonzalez, Fernando F (2015) Growth factors for the treatment of ischemic brain injury (growth factor treatment). Brain Sci 5:165-77
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Knox, Renatta; Brennan-Minnella, Angela M; Lu, Fuxin et al. (2014) NR2B phosphorylation at tyrosine 1472 contributes to brain injury in a rodent model of neonatal hypoxia-ischemia. Stroke 45:3040-7
Sheldon, R Ann; Lee, Christina L; Jiang, Xiangning et al. (2014) Hypoxic preconditioning protection is eliminated in HIF-1? knockout mice subjected to neonatal hypoxia-ischemia. Pediatr Res 76:46-53
van Velthoven, Cindy T J; Sheldon, R Ann; Kavelaars, Annemieke et al. (2013) Mesenchymal stem cell transplantation attenuates brain injury after neonatal stroke. Stroke 44:1426-32
Fang, Annie Y; Gonzalez, Fernando F; Sheldon, R Ann et al. (2013) Effects of combination therapy using hypothermia and erythropoietin in a rat model of neonatal hypoxia-ischemia. Pediatr Res 73:12-7

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