Protein cysteine S-nitrosylation inhibits vesicular uptake of neurotransmitters

Previous studies have shown that nitric oxide can induce cysteine S-nitrosylation of total protein in synaptosomes, suggesting that nitric oxide may contribute to the regulation of synaptic protein function. Vesicular neurotransmitter transporters pack neurotransmitters into synaptic vesicles and play an important role in neurotransmission. In the central nervous system, vesicular monoamine transporter 2 (VMAT2) is responsible for the uptake of monoamines, vesicular acetylcholine transporter (VAChT) is responsible for the uptake of acetylcholine, while vesicular glutamate transporters 1 and 2 (VGLUT1 and VGLUT2) are responsible for the uptake of glutamate. The purpose of this study was to investigate the role of cysteine S-nitrosylation in the regulation of these vesicular neurotransmitter transporters. Using the biotin switch assay followed by avidin precipitation and immunoblotting we found that the nitric oxide donor nitrosoglutathione (GSNO) not only increased total cysteine S-nitrosylation, but also increased cysteine S-nitrosylation of VMAT2, VAChT, VGLUT1 and VGLUT2 in the mouse brain. Further, GSNO also decreased the vesicular uptake of [3H]dopamine, [3H]acetylcholine and [3H]glutamate. Our studies suggest that the cysteine S-nitrosylation may play an important role in the regulation of vesicular neurotransmitter transport.