Transduced PDZ1 domain of PSD-95 decreases Src phosphorylation and increases nNOS (Ser847) phosphorylation contributing to neuroprotection after cerebral ischemia

Research Center for Biochemistry and Molecular Biology, Xuzhou Medical College, Xuzhou, Jiangsu, China.
Brain research (Impact Factor: 2.84). 02/2010; 1328:162-70. DOI: 10.1016/j.brainres.2010.02.055
Source: PubMed


Over-activation of NMDA receptor has been widely believed to be the main signal resulting in ischemic cell injury. We recently reported that the triplicate complex NR2A-PSD-95-Src is a signaling module to facilitate NMDA receptor over-activation. In addition, over-activation of NMDA receptor can activate another signaling molecule nNOS, which is also mediated by PSD-95 after cerebral ischemia. Here, we examined whether overexpression of the PDZ1 domain of PSD-95 could disrupt the functional interaction between NMDA receptor and PSD-95 in rat hippocampal CA1 region, and whether or not it could exert a neuroprotective effect against cerebral ischemia. Our results showed that overexpression of PDZ1 domain not only decreased the assembly of NR2A-PSD-95-Src signaling module and the auto-phosphorylation of Src, which mediates NMDA receptor phosphorylation, but also enhanced nNOS (Ser847) phosphorylation. Most importantly, overexpression of PDZ1 domain protected rat hippocampal CA1 neurons against cerebral ischemia injury. These results suggest that overexpression of the PDZ1 domain can perturb the binding of PSD-95 to NMDA receptor, suppress the activity of both NMDA receptor and nNOS, and thus have a neuroprotective effect.

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    • "It is shown that the NR2A-PSD-95-Src complex plays critical roles in ischemic injury [61], [73]. Inhibition of interactions among NR2A and Src with PSD-95 prevents cell death after transient ischemia [74]. Therefore, sustained zinc exposure may influence the neuronal integrity by decreasing functional NMDARs in sub-lethal conditions. "
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    ABSTRACT: Zinc distributes widely in the central nervous system, especially in the hippocampus, amygdala and cortex. The dynamic balance of zinc is critical for neuronal functions. Zinc modulates the activity of N-methyl-D-aspartate receptors (NMDARs) through the direct inhibition and various intracellular signaling pathways. Abnormal NMDAR activities have been implicated in the aetiology of many brain diseases. Sustained zinc accumulation in the extracellular fluid is known to link to pathological conditions. However, the mechanism linking this chronic zinc exposure and NMDAR dysfunction is poorly understood. We reported that chronic zinc exposure reduced the numbers of NR1 and NR2A clusters in cultured hippocampal pyramidal neurons. Whole-cell and synaptic NR2A-mediated currents also decreased. By contrast, zinc did not affect NR2B, suggesting that chronic zinc exposure specifically influences NR2A-containg NMDARs. Surface biotinylation indicated that zinc exposure attenuated the membrane expression of NR1 and NR2A, which might arise from to the dissociation of the NR2A-PSD-95-Src complex. Chronic zinc exposure perturbs the interaction of NR2A to PSD-95 and causes the disorder of NMDARs in hippocampal neurons, suggesting a novel action of zinc distinct from its acute effects on NMDAR activity.
    PLoS ONE 09/2012; 7(9):e46012. DOI:10.1371/journal.pone.0046012 · 3.23 Impact Factor
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    • "After cerebral ischemia, the SFKs are activated (Hu et al., 1998; Takagi et al., 1999), explaining the marked tyrosine phosphorylation that persists, at least during 24 h of recovery and essentially until neurons degenerate, which implies that excessive and protracted tyrosine phosphorylation of NR2 may contribute to neuronal damage. The latter is supported by findings that suppression of PSD-95 expression attenuates the phosphorylation of NR2A and its interaction with Src and Fyn and is neuroprotective (Hou et al., 2003; Wang et al., 2010). Also, an inhibitor of SFKs protects against ischemic damage in the hippocampus (Hou et al., 2007). "
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    ABSTRACT: Changes in the dynamic interactions of macromolecules in cell membranes appear to underlie the robust neuroprotective effect of hypothermia against selective neuronal degeneration in the CA1 region of the rat hippocampus after transient cerebral ischemia, but the detailed mechanisms are still elusive. Using the two-vessel occlusion model of transient normothermic cerebral ischemia of 15 min duration, we investigated the tyrosine phosphorylation of synaptic proteins in general and that of the NMDA receptor subunits in particular, at different times of recirculation. Specifically, the effect of intra-ischemic hypothermia (33°C), which provides neuroprotection to the CA1 region of the hippocampus, was studied. Phosphorylation of tyrosine residues on the NMDA receptor (NR) 2, but not of the NR1 or the AMPA receptor subunit 1 (GluR1) proteins, was markedly enhanced following cerebral ischemia. Protein tyrosine phosphorylation was persistently increased in the postsynaptic densities of the vulnerable CA1 region, but was transient in the CA3/dentate gyrus (DG) neurons where cell death was not evident. The phospho-tyrosine phosphatase activity decreased during reperfusion in the CA1 region but not in CA3/DG. Importantly, decreasing body temperature to 33°C during ischemia modified the dynamics of the protein tyrosine phosphorylation of NR2 in the CA1 region, which was transient and similar in time course to that seen in the CA3/DG region after normothermic ischemia. We conclude that the protracted tyrosine phosphorylation of the NR2 subunit in the hippocampus CA1 region following normothermic ischemia is attenuated by hypothermia and therefore constitutes an important target for hypothermic neuroprotection.
    11/2011; 1(3):159-164. DOI:10.1089/ther.2011.0013
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    ABSTRACT: Cerebral hypoxic-ischaemic injury is involved in many central nervous system diseases. The mechanisms of neuron injury and death in cerebral hypoxic ischaemia remain unclear. There have been many theories on pathogenesis of neuron injury and death in cerebral hypoxic ischaemia, such as the toxicity of excitatory amino acid, NO, the production of oxygen free radicals, chondriosome injury, complement component, injury of immunological inflammation, matrix metalloproteinase, dopamine, Ca2+ overloading, cell apoptosis and so on. The aim of this review is to describe recent observations regarding the mechanisms of neuron injury and death in cerebral hypoxic ischaemia.
    01/2011; 49(2):78-87.
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