期刊
JOURNAL OF NEUROSCIENCE
卷 26, 期 31, 页码 8195-8205出版社
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.1301-06.2006
关键词
dopamine transporter; HA epitope tag; endocytosis; RNA interference; ubiquitination; Nedd4-2
资金
- NIDA NIH HHS [DA015050, DA014204, DA019980] Funding Source: Medline
The function of the dopamine transporter (DAT) to terminate dopamine neurotransmission is regulated by endocytic trafficking of DAT. To elucidate the mechanisms of DAT endocytosis, we generated a fully functional mutant of the human DAT in which a hemagglutinin epitope ( HA) was incorporated into the second extracellular loop. The endocytosis assay, based on the uptake of an HA antibody, was designed to study constitutive-and protein kinase C(PKC)-dependent internalization of HA-DAT expressed in non-neuronal cells and rat dopaminergic neurons. Large-scale RNA interference analysis of PKC-dependent endocytosis of HA-DAT revealed the essential and specific role of an E3 ubiquitin ligase, Nedd4-2 (neural precursor cell expressed, developmentally downregulated 4-2), as well as the involvement of adaptor proteins present in clathrin-coated pits, such as epsin, Eps15 ( epidermal growth factor pathway substrate clone 15), and Eps15R (Eps15-related protein). Depletion of Nedd4-2 resulted in a dramatic reduction of PKC-dependent ubiquitination of DAT. Endogenous Nedd4-2, epsin, and Eps15 were coimmunoprecipitated with heterologously expressed human HA-DAT and endogenous DAT isolated from rat striatum. A new mechanistic model of DAT endocytosis is proposed whereby the PKC-induced ubiquitination of DAT mediated by Nedd4-2 leads to interaction of DAT with adaptor proteins in coated pits and acceleration of DAT endocytosis.
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