Parkinson's disease (PD) is characterized by a selective degeneration of dopaminergic neurons in the substantia nigra, resulting in irreversible motor dysfunction. While the pathology of the disease is well established, the cellular mechanisms underlying the degeneration of dopaminergic neurons remain enigmatic. Evidence from cell culture studies, animal models, and post-mortem analyses consistently demonstrates that apoptosis is the major mode of cell death in PD, in which oxidative stress might play a critical role. The key markers of dopaminergic cell death, including reactive oxygen species (ROS) generation, caspase-3 activation, and DNA fragmentation, have been extensively evaluated. However, little is understood about the downstream cellular events of caspase-3 activation that lead to DNA fragmentation. As outlined in the preliminary data, we have identified that protein kinase C-delta (PKCd), a member of the novel PKC isoform family, is an oxidative stress kinase that is highly expressed in nigral dopaminergic neurons and serves as a key substrate for caspase-3. PKCd is proteolytically cleaved into regulatory and catalytic subunits by caspase-3 to persistently increase its kinase activity, which further contributes to apoptosis in cell culture models of PD. Therefore, we will extend our preliminary findings by pursuing the following specific aims: (i) To systematically characterize the caspase-3 dependent proteolytic activation of PKCd and its role in dopaminergic neuronal apoptosis in animal models of Parkinson's disease, (ii) To investigate whether tyrosine phosphorylation of PKCd by non-receptor tyrosine kinases during oxidative stress promotes the caspase-3 dependent proteolytic activation of PKCd to induce apoptosis in dopaminergic neurons. If so, identify the upstream tyrosine kinase that regulates the proapoptotic function of PKCd, (iii) To establish the proapoptotic function of PKCd in nigral dopaminergic degeneration using PKCd knockout (PKCd -/-) C57 black mice, and (iv) To determine the potential neuroprotective effects of the PKCd inhibitor rottlerin, non-receptor tyrosine kinase inhibitors, and siRNA against PKCd in the MPTP mouse model of PD. Cellular, molecular, and behavioral approaches will be used to delineate these specific aims. Together, results from the proposed systematic investigation will illuminate the cellular mechanisms underlying the oxidative stress dependent apoptotic cell death process in dopaminergic degeneration, and this knowledge will advance the development of more targeted and innovative therapeutic strategies for the treatment of PD.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS038644-10
Application #
7389528
Study Section
Clinical Neuroplasticity and Neurotransmitters Study Section (CNNT)
Program Officer
Sieber, Beth-Anne
Project Start
1999-04-01
Project End
2010-03-31
Budget Start
2008-04-01
Budget End
2009-03-31
Support Year
10
Fiscal Year
2008
Total Cost
$253,609
Indirect Cost
Name
Iowa State University
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
005309844
City
Ames
State
IA
Country
United States
Zip Code
50011
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Afeseh Ngwa, Hilary; Kanthasamy, Arthi; Anantharam, Vellareddy et al. (2009) Vanadium induces dopaminergic neurotoxicity via protein kinase Cdelta dependent oxidative signaling mechanisms: relevance to etiopathogenesis of Parkinson's disease. Toxicol Appl Pharmacol 240:273-85
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