A novel mechanism underlying the susceptibility of neuronal cells to nitric oxide: the occurrence and regulation of protein S-nitrosylation is the checkpoint.
The susceptibility of neuronal cells to nitric oxide (NO) is a key issue in NO-mediated neurotoxicity. However, the underlying mechanism remains unclear. As a cyclic guanosine monophosphate (cGMP)-independent NO signaling pathway, S-nitrosylation (or S-nitrosation) has been suggested to occur as a post-translational modification in parallel with O-phosphorylation. The underlying mechanism of the involvement of protein S-nitrosylation in the susceptibility of neuronal cells to NO has been little investigated. In this study, we focused on the role of S-nitrosothiols (RSNO) in the susceptibility of a cerebellar cell line R2 to NO. Our results showed the following: (i) S-nitrosoglutathione (GSNO) induced a burst of RSNO in GSH-depleted R2 cells, the majority of which were primarily contributed by the S-nitrosylation of proteins (Pro-SNOs), and was followed by severe neuronal necrosis; (ii) the elevation in the level of Pro-SNOs resulted from a dysfunction of S-nitroglutathione reductase (GSNOR) as a result of its substrate, GSNO, being unavailable in GSH-depleted cells. In the meantime, the suppression of GSNOR increased NO-mediated neurotoxicity in R2 cells, as well as in cerebellar granule neurons; (iii) Our results also demonstrate that the burst of RSNO is the "checkpoint" of cell fate: if RSNO can be reduced to free thiol proteins, cells will survive; if they are further oxidized, cells will die; and (iv) GSH-ethyl ester and Vitamin C protected R2 cells against GSNO neurotoxicity through two distinct mechanisms: by inhibiting the elevation of Pro-SNOs and by reducing Pro-SNOs to free thiol proteins, respectively. A novel mechanism underlying the susceptibility of neuronal cells to NO is proposed and some potential strategies to prevent the NO-mediated neurotoxicity are discussed.
He
J
J
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
Wang
T
T
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
Wang
P
P
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
Han
P
P
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
Yin
Q
Q
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
Chen
C
C
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, ChinaGraduate School of the Chinese Academy of Sciences, Beijing, China.
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism* / Q000633:toxicity; D009574:Nitro Compounds / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026422:S-Nitrosoglutathione / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013438:Sulfhydryl Compounds / Q000378:metabolism
D009419:Nerve Tissue Proteins; D009574:Nitro Compounds; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D005978:Glutathione