Role of Cdk5-Mediated Phosphorylation of Prx2 in MPTP Toxicity and Parkinson's Disease

Abstract

We reported previously that calpain-mediated Cdk5 activation is critical for mitochondrial toxin-induced dopaminergic death. Here, we report a target that mediates this loss. Prx2, an antioxidant enzyme, binds Cdk5/p35. Prx2 is phosphorylated at T89 in neurons treated with MPP+ and/or MPTP in animals in a calpain/Cdk5/p35-dependent manner. This phosphorylation reduces Prx2 peroxidase activity. Consistent with this, p35-/- neurons show reduced oxidative stress upon MPP+ treatment. Expression of Prx2 and Prx2T89A, but not the phosphorylation mimic Prx2T89E, protects cultured and adult neurons following mitochondrial insult. Finally, downregulation of Prx2 increases oxidative stress and sensitivity to MPP+. We propose a mechanistic model by which mitochondrial toxin leads to calpain-mediated Cdk5 activation, reduced Prx2 activity, and decreased capacity to eliminate ROS. Importantly, increased Prx2 phosphorylation also occurs in nigral neurons from postmortem tissue from Parkinson's disease patients when compared to control, suggesting the relevance of this pathway in the human condition.

BAG2 Gene-mediated Regulation of PINK1 Protein Is Critical for Mitochondrial Translocation of PARKIN and Neuronal Survival

“…Cortical neurons were dissected from embryonic days 14.5-15.5 WT CD1, pink1 (C57BL/6), or parkin C57BL/6 mice. The primary cortical neurons were maintained in Neurobasal medium (Invitrogen) supplemented with B27 with antioxidants (Invitrogen), N2 (Invitrogen), 0.5 mM L-glutamine (Sigma), and penicillin/streptomycin (Invitrogen) as described previously (29,30).…”

“…24 h after transfection, the neurons were treated with 20 M MPP ϩ for 48 h and assessed for survival as described previously (30). Briefly, following fixation, GFP-positive neurons were assessed for nuclear integrity as determined by Hoechst staining.…”

“…24 h after transfection, the neurons were treated with 20 M MPP ϩ for 48 h. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was carried out. Briefly, the neurons were incubated with 10 l of 5 mg/ml MTT for 4 h. After removal of the medium with MTT, 100 l of solubilization buffer was applied for extracting the converted MTT for 2 h. The plate was read at 570 nm by a plate reader (30).…”

S-Nitrosylation activates Cdk5 and contributes to synaptic spine loss induced by β-amyloid peptide

“…As a predominantly neuronalspecific kinase, Cdk5 lacks a role in cell-cycle control but has been implicated in an array of neuronal functions, including cell survival, axon guidance, neuronal migration, and regulation of synaptic spine density (4)(5)(6). Dysregulation of Cdk5 activity may play a role in the pathogenesis of stroke and several neurodegenerative disorders, including Alzheimer's disease (AD), amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease (7)(8)(9)(10)(11). Cdk5 is also hyperactivated in response to oxidative stress, mitochondrial dysfunction, excitotoxicity, amyloid-β (Aβ) exposure, calcium overload, and neuroinflammation, thus contributing to neuronal damage.…”

Cdk5 interacts with Hif-1α in neurons: A new hypoxic signalling mechanism?

“…In vitro, both Cdk5 and p35 have been localised to the soma and along neurites (Nikolic et al, 1998;Qu et al, 2007) as well as the nucleus (O'Hare et al, 2005). Although p35 localisation was unaffected, hypoxia caused redistribution of Cdk5 from over the entire cell to mainly the neuronal soma, suggesting an altered function for the kinase and possible interaction with aberrant proteins.…”