Sunday, November 24, 2024
11/24/2024
PROJECT SUMMARY Accumulating evidence suggests that following ischemic stroke hypoperfused brain tissue is functionally disabled as electrical communication among penumbral neurons is disrupted due to marked reductions in oxidative metabolism. Thus, it is apparent that mitochondrial dysfunction plays a central role in the degree of neuronal cell death encountered following ischemic brain injury; however, mitochondria have been slow to be fully investigated. Through a serendipitous discovery of an off-target therapeutic effect of pioglitazone, a small mitochondrial iron-sulfur cluster protein, mitoNEET (mNT) was identified that has renewed interest in therapeutic targeting of mitochondria. MitoNEET is embedded in the outer mitochondrial membrane and acts as a redox and pH sensor to regulate mitochondrial bioenergetics, especially in response to cellular stress. Using pioglitazone as our parent compound, we designed NL-1, a first-in-class ligand with high specificity for mN. Using NL-1, we have demonstrated marked improvements in stroke neuropathology and functional impairment following transient middle cerebral artery occlusion (MCAO) in mice and rats. The objective of this proposal is to address fundamental gaps in knowledge regarding how mNT works within the brain to mitigate acute ischemic brain injury. Our central hypothesis is that modulation of mNT acts to improve vulnerable neurons within the penumbra by reducing the vicious cycle of excessive iron-induced lipid peroxidation and increased neuronal death. Based on a strong body of prior literature and pilot data, we postulate the initial target of activity for NL-1 is the cerebral microvasculature; thus, we propose two specific aims to test our hypothesis. In specific aim 1, we will test if mNT selective ligand, NL-1, mitigates ferroptosis using a 4 cell Transwell in vitro model of the blood- brain barrier following oxygen-glucose deprivation with reperfusion. Whereas, in specific aim 2, we will test if mNT ligand, NL-1, reduces brain iron accumulation and blood-brain barrier dysfunction post-MCAO. Successful completion of the proposed research is expected to provide a: (1) greater understanding of how & where mNT mitigates brain injury following ischemic stroke; (2) new insight into the impact of mitochondrial dysfunction & diminished bioenergetics on ischemic stroke outcomes; & (3) strong scientific foundation for an interventional therapeutic approach for treating ischemic stroke. The mechanistic & preclinical data obtained through these studies will serve as critical milestones for advancing the development of mitochondria-targeted therapies for treating neurological injuries & disease.
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