RT Journal Article
SR Electronic
T1 Activation of Protein Kinase C Inhibits Uptake, Currents and Binding Associated with the Human Dopamine Transporter Expressed in<em>Xenopus</em> Oocytes
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 1358
OP 1365
VO 282
IS 3
A1 Si-Jia Zhu
A1 Michael P. Kavanaugh
A1 Mark S. Sonders
A1 Susan G. Amara
A1 Nancy R. Zahniser
YR 1997
UL http://jpet.aspetjournals.org/content/282/3/1358.abstract
AB Activation of protein kinase C (PKC) regulates the activity of a number of neurotransmitter transporters. When Xenopus oocytes expressing the cloned human dopamine transporter (hDAT) were pretreated with bath-applied phorbol 12-myristate 13-acetate (PMA), a PKC activator, [3H]DA uptake decreased irreversibly in a time- and dose-dependent manner (IC50 = 22 nM; maximal inhibition = 63–85%). The inhibition appeared to be PKC-specific because incubation with the inactive form of phorbol ester 4α-phorbol-12,13-didecanoate (400 nM) did not change the uptake activity and PMA (100 nM) inhibition could be partially blocked by the selective PKC inhibitor bisindolylmaleimide I (1 μM). Saturation studies of [3H]DA uptake showed that PMA-induced inhibition was due to a decrease in Vmax with no change in KT. Similar to uptake, PMA pretreatment inhibited both the hDAT transport-associated and substrate-independent leak currents. PMA also decreased membrane capacitance (Cm) by 40%, selectively in hDAT-expressing oocytes. In addition, PMA pretreatment resulted in a 77% decrease in Bmax of [3H]mazindol binding to intact oocytes. In contrast, binding to whole homogenates of PMA-pretreated oocytes was not significantly altered. These results suggest that PMA regulates hDAT expressed in Xenopus oocytes by altering cell surface trafficking of hDAT. The American Society for Pharmacology and Experimental Therapeutics