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S-nitrosylation of c-Src via NMDAR-nNOS module promotes c-Src activation and NR2A phosphorylation in cerebral
Li-Juan Tang1, Chong Li, Shu-Qun Hu
1Research Center of Biochemistry and Molecular Biology and Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou 221002, Jiangsu, People's Republic of China.
Abstract:
Previous studies suggested that activated c-Src promote the tyrosine phosphorylation of NMDA receptor subunit NR2A, and thus aggravate the injury induced by transient cerebral ischemia/reperfusion (I/R) in rat hippocampus CA1 region. In this study, we examined the effect of nitric oxide (NO) on the activation of c-Src and the tyrosine phosphorylation of NMDA receptor NR2A subunit. The results show that S-nitrosylation and the phosphorylation of c-Src were induced after cerebral I/R in rats, and administration of nNOS inhibitor 7-NI, nNOS antisense oligonucleotides and exogenous NO donor sodium nitroprusside diminished the increased S-nitrosylation and phosphorylation of c-Src during cerebral I/R. The cysteine residues of c-Src modified by S-nitrosylation are Cys489, Cys498, and Cys500. On the other hand, NMDAR antagonist MK-801 could attenuate the S-nitrosylation and activation of c-Src. Taken together, the S-nitrosylation of c-Src is provoked by NO derived from endogenous nNOS, which is activated by Ca(2+) influx from NMDA receptors, and promotes the auto-phosphorylation at tyrosines and further phosphorylates NR2A. The molecular mechanism we outlined here is a novel postsynaptic NMDAR-nNOS/c-Src-mediated signaling amplification, the 'NMDAR-nNOS → NO → SNO-c-Src → p-c-Src → NMDAR-nNOS' cycle, which presents the possibility as a potential therapeutic target for stroke treatment.
Insights
Nitric oxide (NO) activates c-Src through S-nitrosylation, leading to NMDA receptor phosphorylation and exacerbating stroke injury. Targeting this NMDAR-nNOS/c-Src pathway offers a potential therapeutic strategy for stroke treatment.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Previous studies implicated activated c-Src in NMDA receptor subunit NR2A phosphorylation, worsening cerebral ischemia/reperfusion (I/R) injury.
- The role of nitric oxide (NO) in c-Src activation and NMDA receptor phosphorylation following cerebral I/R remained unclear.
Purpose of the Study:
- To investigate the effect of NO on c-Src activation and NMDA receptor NR2A subunit tyrosine phosphorylation in a rat model of cerebral I/R.
- To elucidate the molecular mechanism linking NMDA receptors, nNOS, NO, and c-Src in postsynaptic signaling.
Main Methods:
- Cerebral I/R model in rats.
- Administration of nNOS inhibitor (7-NI), nNOS antisense oligonucleotides, NO donor (sodium nitroprusside), and NMDAR antagonist (MK-801).
- Analysis of c-Src S-nitrosylation, tyrosine phosphorylation, and NMDA receptor NR2A phosphorylation.
Main Results:
- Cerebral I/R induced S-nitrosylation and phosphorylation of c-Src.
- Inhibition of nNOS or NMDA receptors attenuated c-Src S-nitrosylation and activation.
- Specific cysteine residues (Cys489, Cys498, Cys500) on c-Src were identified as sites of S-nitrosylation.
- NO derived from nNOS, activated by NMDA receptor-mediated Ca(2+) influx, was shown to S-nitrosylate and activate c-Src, which then phosphorylated NR2A.
Conclusions:
- A novel postsynaptic signaling cascade, the 'NMDAR-nNOS → NO → SNO-c-Src → p-c-Src → NMDAR-nNOS' cycle, amplifies neuronal injury after cerebral I/R.
- This NO-mediated S-nitrosylation and activation of c-Src represents a potential therapeutic target for stroke treatment.
