D2 dopamine receptors interact directly with N-type calcium channels and regulate channel surface expression levels.
N-type channels are located on dendrites and at pre-synaptic nerve terminals where they play a fundamental role in neurotransmitter release. They are potently regulated by the activation of a number of different types of pertussis toxin (PTX)-sensitive G alpha(i/o) coupled receptors, which results in voltage-dependent inhibition of channel activity via G betagamma subunits. Using heterologous expression in HEK 293T cells, we show via whole cell patch clamp recordings that D2 receptors mediate both G betagamma (i.e., voltage-dependent) and voltage-independent inhibition of channel activity. Furthermore, using co-immunoprecipitation and pull down assays involving the intracellular regions of each protein, we show that D2 receptors and N-type channels form physical signaling complexes. Finally, we use confocal microscopy to demonstrate that D2 receptors regulate N-type channel trafficking to affect the number of calcium channels available at the plasma membrane. Taken together, these data provide evidence for multiple voltage-dependent and voltage-independent mechanisms by which D2 receptor subtypes influence N-type channel activity.
Kisilevsky
Alexandra E
AE
Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
Zamponi
Gerald W
GW
D000818:Animals; D002118:Calcium / Q000737:chemistry*; D020864:Calcium Channels, N-Type / Q000737:chemistry / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D018613:Microscopy, Confocal; D037342:Pertussis Toxin / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction
D020864:Calcium Channels, N-Type; D017448:Receptors, Dopamine D2; D037342:Pertussis Toxin; D005982:Glutathione Transferase; D002118:Calcium