Neuroprotection against ischaemic brain injury by a GluR6-9c peptide containing the TAT protein transduction sequence

Abstract

It is well documented that N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors play a pivotal role in ischaemic brain injury. Recent studies have shown that kainate (KA) receptors are involved in neuronal cell death induced by seizure, which is mediated by the GluR6*PSD-95*MLK3 signalling module and subsequent c-Jun N-terminal kinase (JNK) activation. Here we investigate whether GluR6 mediated JNK activation is correlated with ischaemic brain injury. Our results show that cerebral ischaemia followed by reperfusion can enhance the assembly of the GluR6*PSD-95*MLK3 signalling module and JNK activation. As a result, activated JNK can not only phosphorylate the transcription factor c-Jun and up-regulate Fas L expression but can also phosphorylate 14-3-3 and promote Bax translocation to mitochondria, increase the release of cytochrome c and increase caspase-3 activation. These results indicate that GluR6 mediated JNK activation induced by ischaemia/reperfusion ultimately results in neuronal cell death via nuclear and non-nuclear pathways. Furthermore, the peptides we constructed, Tat-GluR6-9c, show a protective role against neuronal death induced by cerebral ischaemia/reperfusion through inhibiting the GluR6 mediated signal pathway. In summary, our results indicate that the KA receptor subunit GluR6 mediated JNK activation is involved in ischaemic brain injury and provides a new approach for stroke therapy.

Neuroprotection of Tat-GluR6-9c against Neuronal Death Induced by Kainate in Rat Hippocampus via Nuclear and Non-nuclear Pathways

“…S7100) was purchased from Chemicon International, Inc. KA was from BIOMOL. Tat-GluR6-9c (Arg-Leu-Pro-Gly-Lys-Glu-Thr-MetAla, GluR6-9c), a 20-amino acid fusion peptide with Tat protein (Tyr-Gly-Arg-Lys-Lys-Arg-Arg-Gln-Arg-Arg-Arg), and Tat-GluR6AA (Tat-Arg-Leu-Pro-Gly-Lys-Ala-Ala-Asp-Asp) were constructed in our laboratory (19).…”

“…In a previous study (19), we demonstrated that Tat-GluR6-9c, a GluR6 C terminus-containing peptide conjugated to the cell membrane transduction sequence of the human immunodeficiency virus Tat protein, can be delivered into hippocampal neurons in vitro and in vivo. In the present study, we demonstrate that Tat-GluR6-9c can perturb the interaction of GluR6 with PSD95 and suppress the assembly of the * This work was supported by Grant 30330190 from the Key Project of the National Natural Science Foundation of China.…”

The taming of the cell penetrating domain of the HIV Tat: Myths and realities

“…Subsequently, several other studies have also reported effective biodistribution of therapeutically important proteins in vivo by using PTD [52,[69][70][71][72][73][74][75]. In a previous study, however, no PTD mediated transduction in brain was observed, [46] possibly because beta-gal was chemically conjugated to PTD instead of recombinant fusion protein.…”

Tyrosine phosphorylation of GluK2 up-regulates kainate receptor-mediated responses and downstream signaling after brain ischemia

“…Excessive stimulation of GluK2-containing kainate receptors mediates the activation of proapoptotic JNK3 signaling, which is responsible for postischemic delayed neuronal loss (24). It has been found that sustained agonist treatment induces the endocytosis of GluK2-containing kainate receptors (31).…”

“…Glutamate-induced intracellular Ca 2+ ([Ca 2+ ] i ) overload is a major mechanism underlying excitotoxicity and ischemic cell death. Furthermore, excessive activation of GluK2-containing kainate receptors triggers the proapoptotic JNK signal cascade, which contributes to ischemic brain damage (23,24). These findings suggest that GluK2-containing kainate receptor-mediated responses are critical events in the induction of neuronal cell death after stroke.…”