Tolerance, the cellular response to mild stress, which protects against a toxic stress, is a conserved feature of many organisms. Classic tolerance is gene-mediated, protein synthesis-dependent and requires at least 24 hours to occur. In contrast, rapid ischemic tolerance occurs within 1 hour of the preconditioning ischemia and is not dependent on the synthesis of new proteins. As such understanding the endogenous mechanism of neuroprotection which are involved in rapid ischemic tolerance, may identify novel fast acting therapeutic strategies to treat acute stroke. Our preliminary data suggests that cell death promoting proteins are rapidly down regulated, following preconditioning, which may account for the neuroprotective effects observed in rapid ischemic tolerance. Our central hypothesis is that brief ischemia stimulates the generation of rapid ischemic tolerance by acute alterations in the levels of cell death promoting proteins by the process of ubiquitination, which targets the proteins for degradation by the proteasome.
The specific aims are:-1. We will test our hypothesis using a candidate cell death promoting protein, Bim. Experiments are designed to investigate Bim ubiquitination and degradation in the 1 hour period following ischemic preconditioning. 2. We will further test our hypothesis broadly with immunoprecipitation and mass spectrographic analysis to identify novel proteins that are ubiquitinated following preconditioning ischemia. Experiments will then further validate this data, and identify potential new targets for regulating cell death following ischemia. These studies will support our hypothesis that protein down regulation is a powerful endogenous neuroprotective mechanism in the brain. We will identify the molecular mechanisms that favor the degradation of pro-apoptotic proteins, which may offer new acute therapeutic targets for the treatment of stroke and other neurological insults, which would not be available via gene modulation strategies based on classic tolerance, requiring over 24h to exert a neuroprotective effect.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21NS050669-02
Application #
6987922
Study Section
Special Emphasis Panel (ZRG1-BDCN-D (01))
Program Officer
Hicks, Ramona R
Project Start
2005-01-15
Project End
2007-06-30
Budget Start
2006-01-01
Budget End
2007-06-30
Support Year
2
Fiscal Year
2006
Total Cost
$175,007
Indirect Cost
Name
Emanuel Hospital and Health Center
Department
Type
DUNS #
050973098
City
Portland
State
OR
Country
United States
Zip Code
97232
Thompson, Simon; Pearson, Andrea N; Ashley, Michelle D et al. (2011) Identification of a novel Bcl-2-interacting mediator of cell death (Bim) E3 ligase, tripartite motif-containing protein 2 (TRIM2), and its role in rapid ischemic tolerance-induced neuroprotection. J Biol Chem 286:19331-9
Meller, Robert (2009) The role of the ubiquitin proteasome system in ischemia and ischemic tolerance. Neuroscientist 15:243-60
Loftus, Liam T; Gala, Rosaria; Yang, Tao et al. (2009) Sumo-2/3-ylation following in vitro modeled ischemia is reduced in delayed ischemic tolerance. Brain Res 1272:71-80
Meller, Robert; Thompson, Simon John; Lusardi, Theresa Ann et al. (2008) Ubiquitin proteasome-mediated synaptic reorganization: a novel mechanism underlying rapid ischemic tolerance. J Neurosci 28:50-9
Thompson, Simon J; Loftus, Liam T; Ashley, Michelle D et al. (2008) Ubiquitin-proteasome system as a modulator of cell fate. Curr Opin Pharmacol 8:90-5
Meller, Robert; Cameron, Jennifer Anastasia; Torrey, Daniel John et al. (2006) Rapid degradation of Bim by the ubiquitin-proteasome pathway mediates short-term ischemic tolerance in cultured neurons. J Biol Chem 281:7429-36