PT  - JOURNAL ARTICLE
AU  - Metta Pinthong
AU  - Stefanie A. G. Black
AU  - Fabiola M. Ribeiro
AU  - Chumpol Pholpramool
AU  - Stephen S. G. Ferguson
AU  - R. Jane Rylett
TI  - Activity and Subcellular Trafficking of the Sodium-Coupled Choline Transporter CHT Is Regulated Acutely by Peroxynitrite
AID  - 10.1124/mol.107.040881
DP  - 2008 Mar 01
TA  - Molecular Pharmacology
PG  - 801--812
VI  - 73
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/73/3/801.short
4100  - http://molpharm.aspetjournals.org/content/73/3/801.full
SO  - Mol Pharmacol2008 Mar 01; 73
AB  - Excess formation of nitric oxide and superoxide by-products (peroxynitrite, reactive oxygen, and reactive nitrogen species) attenuates cholinergic transmission potentially having a role in Alzheimer disease pathogenesis. In this study, we investigated mechanisms by which acute exposure to peroxynitrite impairs function of the sodium-dependent hemicholinium-3 (HC-3)-sensitive choline transporter (CHT) that provides substrate for acetylcholine synthesis. The peroxynitrite generator 3-morpholinosydnonimine (SIN-1) acutely inhibited choline uptake in cells stably expressing FLAG-tagged rat CHT in a dose- and time-dependent manner, with an IC50 = 0.9 ± 0.14 mM and t½ = 4 min. SIN-1 significantly reduced Vmax of choline uptake without altering the Km. This correlated with a SIN-1-induced decrease in cell surface CHT protein, observed as lowered levels of HC-3 binding and biotinylated CHT at the plasma membrane. It is noteworthy that short-term exposure of cells to SIN-1 accelerated the rate of internalization of CHT from the plasma membrane, but it did not alter return of CHT back to the cell surface. SIN-1 did not disrupt cell membrane integrity or cause cell death. Thus, the inhibitory effect of SIN-1 on choline uptake activity and HC-3 binding was related to enhanced internalization of CHT proteins from the plasma membrane to subcellular organelles. The American Society for Pharmacology and Experimental Therapeutics