Many adult human illnesses including Alzheimer's disease (AD), and Parkinson's disease and amyotrophic lateral sclerosis (ALS) involve pathologic change of neurons, which results in their loss through apoptosis. The long-term objective of this research in our laboratory is to understand how signal-controlled intracellular mechanisms regulate neuronal survival and apoptosis during development and neurodegeneration. Studies have shown that cyclin dependent kinase 5 (Cdk5) plays a key role in the apoptosis of mature neurons. Our recent findings suggest that Cdk5 functions in the nucleus to regulate apoptosis. We propose in the present application to identify novel nuclear mechanisms by which Cdk5 induces neuronal apoptosis.
Our specific aims are: 1. to identify and characterize novel regulatory targets of Cdk5 in neuronal nucleus; 2. to explore regulation of p38 MAPK signaling pathway by Cdk5 in neurons; and 3. to identify and characterize additional Cdk5 regulatory sites in MEF2 (myocyte enhancer factor 2). To identify novel nuclear substrates of Cdk5, we will use Cdk5 binding assays to first isolate proteins from nuclear preparations of primary neurons and reveal their identify by Mass phosphorylation by mutagenesis. We will assess how Cdk5-mediated phosphorylation of p38 MAPK affects its subcellular localization and Spectrometer analysis. We will then confirm them as Cdk5 substrates in biochemical and biological assays. To explore whether Cdk5 directly regulates p38 MAPK pathway, we will test if p38 MAPK is a substrate of Cdk5 by in vitro kinase assays and in vivo phosphorylation studies. We will determine sites of regulation of its downstream targets. We will test Cdk5-mediated phosphorylation of p38 MAPK in models of neurotoxin-induced apoptosis. We will also explore whether Cdk5 directly regulates p38 MAPK upstream activators. Additional regulatory sites in various isoforms of MEF2 will be identified by mutagenesis. The potential effects of Cdk5-mediated phosphorylation of alternatively spliced MEF2C variants will be assessed using MEF2C mutants in reporter gene activation assays and neuronal survival assays. Identifying these novel nuclear regulatory targets of Cdk5 will allow us to explore the mechanisms by which Cdk5 regulates the survival machinery in the nucleus. This should further our understanding of the molecular process of neurotoxin-induced apoptosis, which underlies the pathogenesis of many neurodegenerative diseases ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS048254-03
Application #
6849743
Study Section
Neurodegeneration and Biology of Glia Study Section (NDBG)
Program Officer
Golanov, Eugene V
Project Start
2004-08-01
Project End
2009-08-31
Budget Start
2005-09-01
Budget End
2006-08-31
Support Year
3
Fiscal Year
2005
Total Cost
$283,050
Indirect Cost
Name
Emory University
Department
Neurology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Gao, Li; She, Hua; Li, Wenming et al. (2014) Oxidation of survival factor MEF2D in neuronal death and Parkinson's disease. Antioxid Redox Signal 20:2936-48
She, Hua; Yang, Qian; Mao, Zixu (2012) Neurotoxin-induced selective ubiquitination and regulation of MEF2A isoform in neuronal stress response. J Neurochem 122:1203-10
Wei, Gengze; Yin, Yue; Li, Wenming et al. (2012) Calpain-mediated degradation of myocyte enhancer factor 2D contributes to excitotoxicity by activation of extrasynaptic N-methyl-D-aspartate receptors. J Biol Chem 287:5797-805
Yao, Lu; Li, Wenming; She, Hua et al. (2012) Activation of transcription factor MEF2D by bis(3)-cognitin protects dopaminergic neurons and ameliorates Parkinsonian motor defects. J Biol Chem 287:34246-55
Wen, Yi; Li, Wenjun; Poteet, Ethan C et al. (2011) Alternative mitochondrial electron transfer as a novel strategy for neuroprotection. J Biol Chem 286:16504-15
She, Hua; Mao, Zixu (2011) Regulation of myocyte enhancer factor-2 transcription factors by neurotoxins. Neurotoxicology 32:563-6
She, Hua; Yang, Qian; Shepherd, Kennie et al. (2011) Direct regulation of complex I by mitochondrial MEF2D is disrupted in a mouse model of Parkinson disease and in human patients. J Clin Invest 121:930-40
Zhu, Jinqiu; Li, Wenming; Mao, Zixu (2011) Cdk5: mediator of neuronal development, death and the response to DNA damage. Mech Ageing Dev 132:389-94
Yang, Qian; Mao, Zixu (2010) Parkinson disease: a role for autophagy? Neuroscientist 16:335-41
Yang, Qian; Mao, Zixu (2010) Dysregulation of autophagy and Parkinson's disease: the MEF2D link. Apoptosis 15:1410-4

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