title: Sigma(2)-receptor regulation of dopamine transporter via activation of protein kinase C.
abstract: The elucidation of the mechanisms underlying sigma(2)-receptor activation and signal transduction is crucial to the understanding of sigma(2)-receptor function. Previous studies in our laboratory have demonstrated sigma(2)-receptor-mediated regulation of the dopamine transporter (DAT) as measured by amphetamine-stimulated release of [(3)H]dopamine (DA) from both rat striatal slices and PC12 cells. The regulation of the DAT in the PC12 cell model was dependent upon activation of Ca(2+)/calmodulin-dependent kinase II. We have now studied the second messenger systems involved in sigma(2)-receptor-mediated regulation of amphetamine-stimulated [(3)H]DA release in rat striatal slices, including Ca(2+)/calmodulin-dependent kinase II, protein kinase C, and sources of calcium required for the enhancement of release produced by sigma(2)-receptor activation. The Ca(2+)/calmodulin-dependent kinase II inhibitors 1-[N,O-bis-(5-isoquionolinesulfonyl)]-N-methyl-L-tyrosyl-4-phenylpiperazine and N-[2-[[[3-(4'-chlorophenyl)-2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4'-methoxy-benzenesulfonamide phosphate did not significantly affect the (+)-pentazocine-mediated enhancement of amphetamine-stimulated [(3)H]DA release. However, we found that an inhibitor of protein kinase C, 3-[1-[3-(dimethylamino)propyl]-1H-indol-3-yl)-1H-pyrrole-2,5-dione, blocks the (+)-pentazocine-mediated enhancement in rat striatal slices. The protein kinase C activator phorbol 12-myristate 13-acetate, but not the inactive isophorbol 4 alpha,9 alpha,12 alpha,13 alpha,20-pentahydroxytiglia-1,6-dien-3-one, enhanced the amphetamine-stimulated [(3)H]DA release comparable to the enhancement seen by (+)-pentazocine alone. Additionally, the L-type voltage-dependent calcium channel inhibitor nitrendipine or prior treatment with thapsigargin, but not the N-type voltage-dependent calcium channel omega-conotoxin MVIIA, attenuated the (+)-pentazocine-mediated enhancement. Together, these data suggest that activation of sigma(2)-receptors results in the regulation of DAT activity via a calcium- and protein kinase C-dependent signaling mechanism.
authors.affiliation: Department of Pharmacology, The George Washington University Medical Center, Washington, DC 20037, USA.
authors.forename: Alicia E
authors.initials: AE
authors.lastname: Derbez
authors.forename: Rupal M
authors.initials: RM
authors.lastname: Mody
authors.forename: Linda L
authors.initials: LL
authors.lastname: Werling
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000378:metabolism*; D009294:Narcotics / Q000494:pharmacology; D009419:Nerve Tissue Proteins; D010423:Pentazocine / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017480:Receptors, sigma / Q000502:physiology*; D015290:Second Messenger Systems / Q000187:drug effects / Q000502:physiology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D050483:Dopamine Plasma Membrane Transport Proteins; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009294:Narcotics; D009419:Nerve Tissue Proteins; D017480:Receptors, sigma; C493216:Slc6a3 protein, rat; C106107:sigma-2 receptor; D019284:Thapsigargin; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C070515:bisindolylmaleimide I; D010423:Pentazocine; D002118:Calcium; D004298:Dopamine