Stroke is a devastating clinical condition, for which an effective neuroprotective treatment is currently unavailable. In the previous funding period, we have investigated the role of mitochondrial damage in models of cerebral ischemia/reperfusion. Our results support the current concept that mitochondrial-dependent programmed cell death (PCD) and necrosis-triggered neuroinflammation via microglial overactivation are two important mechanisms that additively contribute to ischemic brain injury. Thus, interventions capable of alleviating both neuronal PCD and neuroinflammation during the acute stage may lead to effective neuroprotective therapies for stroke. Apoptosis signal-regulating kinase 1 (ASK1) triggers neuronal PCD via the mitochondrial pathway and may function as an essential component of signaling cascade during microglial activation. The dual functions of ASK1 in neurons and microglia present it as a novel interventional target for stroke. ASK1 is a 160-kDa serine/threonine protein kinase that activates both JNK and p38 MAPK pathways by phosphorylating MKK4/MKK7 and MKK3/MKK6, respectively. ASK1 is activated in cultured neurons by oxidative stress, DNA damage, or ER stress, and its activation has also been detected in vivo in models of cerebral ischemia. However, the signaling mechanisms underlying ASK1 activation in the context of ischemic injury are poorly understood. Furthermore, the direct evidence for a pathological role of ASK1 in ischemic brain injury is scant. This renewal proposal will test the overall hypothesis that specific inhibition of ASK1- dependent signaling cascade protects against ischemic neuronal injury via novel anti- apoptotic and anti-inflammatory mechanisms.
The specific aims are:
Aim 1. Test the novel hypothesis that ischemia triggers persistent ASK1 activation and neuronal PCD after ischemic injury via a positive-feedback signaling cascade involving oxidative stress and calcium deregulation, and ER stress.
Aim 2. Test the novel hypothesis that ASK1 activation contributes to ischemic brain injury via activation of microglia through ASK1/p38-dependent pro-inflammatory signaling.
Aim 3. Test the hypothesis that interventions via disrupting both ASK1/JNK- dependent pro-apoptotic signaling pathway and ASK1/p38-dependent microglial overactivation can confer prolonged neuroprotection and improve neurological outcome after cerebral ischemia. In summary, the proposed studies investigate a novel ASK1 pro-death signaling cascade in cerebral ischemia. A positive outcome of the project not only will have a high impact on enhancing our understanding of the basic molecular mechanisms of ischemic neuronal injury but also shed light on ASK1 as a potential therapeutic target for stroke.

Public Health Relevance

Stroke is a devastating clinical condition for which an effective neuroprotective treatment is currently unavailable. We have identified ASK1 (apoptosis signal-regulating kinase 1) as a promising therapeutic target for the treatment of ischemic brain injury. The objective of this proposal is to investigate whether blockage of the ASK1 signaling cascade in brain can confer long-term neuroprotection and improve neurological outcomes after experimental stroke. This information will be valuable for future development of new therapeutic strategies for the treatment of stroke and, possibly, other neurological disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS045048-08
Application #
8500467
Study Section
Neural Oxidative Metabolism and Death Study Section (NOMD)
Program Officer
Bosetti, Francesca
Project Start
2003-02-01
Project End
2016-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
8
Fiscal Year
2013
Total Cost
$326,039
Indirect Cost
$95,761
Name
University of Pittsburgh
Department
Neurology
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Pu, Hongjian; Jiang, Xiaoyan; Hu, Xiaoming et al. (2016) Delayed Docosahexaenoic Acid Treatment Combined with Dietary Supplementation of Omega-3 Fatty Acids Promotes Long-Term Neurovascular Restoration After Ischemic Stroke. Transl Stroke Res 7:521-534
Jiang, Xiaoyan; Pu, Hongjian; Hu, Xiaoming et al. (2016) A Post-stroke Therapeutic Regimen with Omega-3 Polyunsaturated Fatty Acids that Promotes White Matter Integrity and Beneficial Microglial Responses after Cerebral Ischemia. Transl Stroke Res 7:548-561
Wu, Yun; Wang, Jiayin; Shi, Yejie et al. (2016) Implantation of Brain-derived Extracellular Matrix Enhances Neurological Recovery after Traumatic Brain Injury. Cell Transplant :
Shi, Yejie; Leak, Rehana K; Keep, Richard F et al. (2016) Translational Stroke Research on Blood-Brain Barrier Damage: Challenges, Perspectives, and Goals. Transl Stroke Res 7:89-92
Shi, Yejie; Zhang, Lili; Pu, Hongjian et al. (2016) Rapid endothelial cytoskeletal reorganization enables early blood-brain barrier disruption and long-term ischaemic reperfusion brain injury. Nat Commun 7:10523
Zhang, Wenting; Zhang, Hui; Mu, Hongfeng et al. (2016) Omega-3 polyunsaturated fatty acids mitigate blood-brain barrier disruption after hypoxic-ischemic brain injury. Neurobiol Dis 91:37-46
Stetler, R Anne; Gao, Yanqin; Leak, Rehana K et al. (2016) APE1/Ref-1 facilitates recovery of gray and white matter and neurological function after mild stroke injury. Proc Natl Acad Sci U S A 113:E3558-67
Pu, Hongjian; Jiang, Xiaoyan; Wei, Zhishuo et al. (2016) Repetitive and prolonged omega-3 fatty acid treatment after traumatic brain injury enhances long-term tissue restoration and cognitive recovery. Cell Transplant :
Hu, Xiaoming; Leak, Rehana K; Shi, Yejie et al. (2015) Microglial and macrophage polarization—new prospects for brain repair. Nat Rev Neurol 11:56-64
Zhang, Wenting; Liu, Jia; Hu, Xiaoming et al. (2015) n-3 Polyunsaturated Fatty Acids Reduce Neonatal Hypoxic/Ischemic Brain Injury by Promoting Phosphatidylserine Formation and Akt Signaling. Stroke 46:2943-50

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