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Activity and Subcellular Trafficking of the Sodium-Coupled Choline Transporter CHT Is Regulated Acutely by Peroxynitrite
- Source :
- Molecular Pharmacology; March 2008, Vol. 73 Issue: 3 p801-812, 12p
- Publication Year :
- 2008
-
Abstract
- 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 Vmaxof 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.
Details
- Language :
- English
- ISSN :
- 0026895X and 15210111
- Volume :
- 73
- Issue :
- 3
- Database :
- Supplemental Index
- Journal :
- Molecular Pharmacology
- Publication Type :
- Periodical
- Accession number :
- ejs13860487