Nitrosylation of Vesicular Transporters in Brain of Amyloid Precursor Protein/Presenilin 1 Double Transgenic Mice.

Nitric oxide can attack thiol groups of cysteine residues in proteins and induce protein cysteine S-nitrosylation. Cholinergic and glutamatergic systems are dysregulated in Alzheimer's disease. Vesicular acetylcholine transporter (VAChT) and vesicular glutamate transporter 1 (VGLUT1) are important in packaging acetylcholine and glutamate into vesicles, which is an important step for neurotransmission. Previously we found that VAChT and VGLUT1 can be nitrosylated and that S-nitrosylation of these transporters inhibits vesicular uptake of acetylcholine and glutamate. To understand the role of VAChT and VGLUT1 nitrosylation in the pathophysiological development of Alzheimer's disease, we analyzed nitrosylation of VAChT and VGLUT1 in brain of amyloid precursor protein (APP) and presenilin 1 (PS1) double transgenic mice, an animal model for Alzheimer's disease. Using a Morris water maze test, we found that 9- and 12-month-old APP/PS1 mice showed memory deficit, compared to wild type mice. We further found that total protein nitrosylation was increased in frontal cortex and hippocampus of 9- and 12-month-old APP/PS1 mice. Although nitrosylation of VAChT and VGLUT1 was not changed in hippocampus of 9- and 12-month-old APP/PS1 mice, nitrosylation of VAChT and VGLUT1 was significantly increased in frontal cortex of APP/PS1 mice at these ages. We also found that nitrosylation of VAChT and VGLUT1 was increased in hippocampus (but not frontal cortex) of 3-month-old APP/PS1 mice. These findings suggest that nitrosylation of VAChT and VGLUT1 may be associated with dysfunctional acetylcholinergic and glutamatergic neurotransmission in Alzheimer's disease.