S-Nitrosylation of proline-rich tyrosine kinase 2 involves its activation induced by oxygen-glucose deprivation

Previous studies have demonstrated that activation of proline-rich tyrosine kinase 2 (PYK2) in cerebral ischemia is involved in the modulation of N-methyl-d-aspartate-type (NMDA) glutamate receptor activity and Ca(2+) dynamics, resulting in ischemic neuron death ultimately. A number of reports indicate that PYK2 is a redox sensitive kinase that must be activated by an estrogen-induced reactive oxygen species (ROS). However, the mechanism of PYK2 activation remains incompletely illustrated. Accumulating attention is focused on nitric oxide (NO, a free radical) which plays a critical role in cellular signal transduction through stimulus-coupled S-nitrosylation of cysteine residues. Here we reported that PYK2 over-expressed in human embryonic kidney (HEK293) cells was S-nitrosylated (forming SNO-PYK2) by reacting with GSNO, an exogenous NO donor, at one critical cysteine residue (Cys534) with a biotin switch assay. Moreover, our results showed that S-nitrosylation and phosphorylation of PYK2 over-expressed in SH-SY5Y cells was significantly increased after oxygen-glucose deprivation (OGD). We further investigated whether the activation (phosphorylation) of PYK2 was associated with S-nitrosylation following SH-SY5Y cells OGD. Our results showed that the cysteine534 residue (site of S-nitrosylation) mutant PYK2 over-expressed in SH-SY5Y cells diminished S-nitrosylation of PYK2 and inhibited its phosphorylation induced by OGD. In addition, overexpression of the mutant PYK2 protein could prevent nuclear accumulation and abrogate neuronal cell death compared to wild type PYK2 in SH-SY5Y cells induced by OGD. These data suggest that the activation of PYK2 following OGD may be modulated by S-nitrosylation, which provides a new avenue for stroke therapy by targeting the post-translational modification machinery.