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Involvement of threonine 258 and serine 259 motif in amphetamine-induced norepinephrine transporter endocytosis.
- Source :
- Journal of Neurochemistry; Oct2010, Vol. 115 Issue 1, p23-35, 13p, 8 Graphs
- Publication Year :
- 2010
-
Abstract
- J. Neurochem. (2010) 115, 23-35. d-Amphetamine (AMPH) down-regulates the norepinephrine transporter (NET), although the exact trafficking pathways altered and motifs involved are not known. Therefore, we examined the cellular and molecular mechanisms involved in AMPH-induced NET regulation in human placental trophoblast cells expressing the wild-type (WT)-hNET and the hNET double mutant (DM)-bearing protein kinase C (PKC)-resistant T258A + S259A motif. NET function and surface expression were significantly reduced in cells expressing WT-hNET but not in cells expressing hNET-DM following AMPH treatment. AMPH inhibited plasma membrane recycling of both WT-hNET and hNET-DM. In contrast, AMPH stimulated endocytosis of WT-hNET, and did not affect hNET-DM endocytosis. Although PKC or calcium/calmodulin- dependent kinase-II (CaMKII) inhibition or depletion of calcium failed to block AMPH-mediated down-regulation of WT-hNET, NET-specific blocker desipramine completely prevented AMPH-induced down-regulation. Furthermore, AMPH treatment had no effect on phospho-CaMKII immunoreactivity. The inhibitory potency of AMPH was highest on hNET-DM, intermediary on T258A and S259A single mutants and lowest on WT-hNET. Single mutants exhibited partial resistance to AMPH-mediated down-regulation. AMPH accumulation was similar in cells expressing WT-hNET or hNET-DM. The results demonstrate that reduced plasma membrane insertion and enhanced endocytosis account for AMPH-mediated NET down-regulation, and provide the first evidence that T258/S259 motif is involved only in AMPH-induced NET endocytosis that is desipramine-sensitive, but PKC and CaMKII independent. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00223042
- Volume :
- 115
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Journal of Neurochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 53568266
- Full Text :
- https://doi.org/10.1111/j.1471-4159.2010.06898.x