Document Detail

Peroxynitrite Donor SIN-1 Alters High-Affinity Choline Transporter Activity by Modifying Its Intracellular Trafficking.
MedLine Citation:
PMID:  22514319     Owner:  NLM     Status:  In-Data-Review    
Sodium-coupled, high-affinity choline transporters (CHTs) are inhibited by 3-morpholinosydnonimine (SIN-1) [peroxynitrite (ONOO(-)) donor]; ONOO(-) can be produced from nitric oxide and reactive oxygen species during neurodegeneration. SIN-1 rapidly increases CHT internalization from the cell surface, and this correlates with decreased choline uptake. This study addresses mechanisms by which SIN-1 inhibits CHT function in human neuronal SH-SY5Y cells. Thus, mutant L531A-CHT, which does not constitutively internalize into cells by a clathrin-mediated process, is resistant to SIN-1 effects. This suggests that CHT inhibition is not due to oxidative-nitrosative inactivation of the protein and that decreased levels of cell surface CHT in SIN-1-treated cells is related to alterations in its trafficking and subcellular disposition. Dominant-negative proteins AP180C and dynamin-K44A, which interfere with clathrin-mediated and dynamin-dependent endocytosis, respectively, attenuate CHT inhibition by SIN-1. CHT in both vehicle- and SIN-1-treated cells colocalizes with Rab7, Rab9, and Lamp-1 in late endosomes and lysosomes to a similar extent. Lysosome inhibitors increase choline uptake, suggesting that CHT proteins are normally degraded by lysosomes, and this is not altered by oxidative stress. Unexpectedly, inhibitors of proteasomes, but not lysosomes, attenuate SIN-1-mediated inhibition of choline uptake, indicating that proteasomal degradation plays a role in regulating CHT disposition in SIN-1-treated cells. SIN-1 treatment also enhances CHT ubiquitination. Thus, CHT inhibition in SIN-1-treated cells is mediated by proteasomal degradation, which differs from inhibitory mechanisms for some neurotransmitter transporters under similar conditions. Increased oxidative-nitrosative stress in the microenvironment of cholinergic nerve terminals would diminish cholinergic transmission by reducing choline availability for ACh synthesis.
Leah K Cuddy; Alexis C Gordon; Stefanie A G Black; Ewa Jaworski; Stephen S G Ferguson; R Jane Rylett
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  32     ISSN:  1529-2401     ISO Abbreviation:  J. Neurosci.     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-04-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5573-84     Citation Subset:  IM    
Molecular Brain Research Group, Robarts Research Institute, London, Ontario N6A 5K8, Canada, and Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada, University of Toronto, Toronto, Ontario M5S 1A1, Canada, and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
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