title: Neurotensin triggers dopamine D2 receptor desensitization through a protein kinase C and beta-arrestin1-dependent mechanism.
abstract: The peptide neurotensin (NT) is known to exert a potent excitatory effect on the dopaminergic system by inhibiting D2 dopamine (DA) receptor (D2R) function. This regulation is dependent on activation of PKC, a well known effector of the type 1 NT receptor (NTR1). Because PKC phosphorylation of the D2R has recently been shown to induce its internalization, we hypothesized that NT acts to reduce D2R function through heterologous desensitization of the D2R. In the present study, we first used HEK-293 cells to demonstrate that NT induces PKC-dependent D2R internalization. Furthermore, internalization displayed faster kinetics in cells expressing the D2R short isoform, known to act as an autoreceptor in DA neurons, than in cells expressing the long isoform, known to act as a postsynaptic D2R. In patch clamp experiments on cultured DA neurons, overexpression of a mutant D2S lacking three key PKC phosphorylation sites abrogated the ability of NT to reduce D2R-mediated cell firing inhibition. Short interfering RNA-mediated inhibition of β-arrestin1 and dynamin2, proteins important for receptor desensitization, reduced agonist-induced desensitization of D2R function, but only the inhibition of β-arrestin1 reduced the effect of NT on D2R function. Taken together, our data suggest that NT acutely regulates D2 autoreceptor function and DA neuron excitability through PKC-mediated phosphorylation of the D2R, leading to heterologous receptor desensitization.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Université de Montréal, Québec H3C 3J7, Canada.
authors.forename: Dominic
authors.initials: D
authors.lastname: Thibault
authors.forename: Paul R
authors.initials: PR
authors.lastname: Albert
authors.forename: Graciela
authors.initials: G
authors.lastname: Pineyro
authors.forename: Louis-Éric
authors.initials: LÉ
authors.lastname: Trudeau
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D034285:Dynamin II / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism*; D009496:Neurotensin / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D013570:Synaptic Membranes / Q000235:genetics / Q000378:metabolism; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D017448:Receptors, Dopamine D2; D000071557:beta-Arrestins; D009496:Neurotensin; D011493:Protein Kinase C; D034285:Dynamin II