Cdk5 Phosphorylates Dopamine D2 Receptor and Attenuates Downstream Signaling

Jaehoon Jeong,Daehee Hwang,Yong Song Gho,Seol-Ae Lee,Yongdo Kwak,Sang Ki Park,Dae-Kyum Kim,Haeryun Lee,Saebom Lee,Yoo-Hun Suh,Young-Un Park,James Porter

doi:10.1371/journal.pone.0084482

Jaehoon Jeong, Daehee Hwang + Show 10 more

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https://doi.org/10.1371/journal.pone.0084482

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Abstract

The dopamine D2 receptor (DRD2) is a key receptor that mediates dopamine-associated brain functions such as mood, reward, and emotion. Cyclin-dependent kinase 5 (Cdk5) is a proline-directed serine/threonine kinase whose function has been implicated in the brain reward circuit. In this study, we revealed that the serine 321 residue (S321) in the third intracellular loop of DRD2 (D2i3) is a novel regulatory site of Cdk5. Cdk5-dependent phosphorylation of S321 in the D2i3 was observed in in vitro and cell culture systems. We further observed that the phosphorylation of S321 impaired the agonist-stimulated surface expression of DRD2 and decreased G protein coupling to DRD2. Moreover, the downstream cAMP pathway was affected in the heterologous system and in primary neuronal cultures from p35 knockout embryos likely due to the reduced inhibitory activity of DRD2. These results indicate that Cdk5-mediated phosphorylation of S321 inhibits DRD2 function, providing a novel regulatory mechanism for dopamine signaling.

Highlights

Dopamine signaling is involved in various brain functions including motor coordination, mood control and reward mechanisms [1]
These results indicate that the D2i3 serine 321 residue (S321) residue is a preferential target for Cyclin-dependent kinase 5 (Cdk5)-mediated phosphorylation
We found that Cdk5-mediated phosphorylation of DRD2 at Ser321 was not affected by agonist stimulation, which appears different from GRK- and PKCmediated phosphorylations (Fig. 2D) [32,33]

Summary

Introduction

Dopamine signaling is involved in various brain functions including motor coordination, mood control and reward mechanisms [1]. Antidepressants and mood stabilizer efficacy have been linked to alterations in the cell surface expression of DRD2 or downstream intracellular signaling mediated by PKA, ERK and GSK3 [1,4,6]. Despite these critical roles for DRD2 in the brain, the detailed regulatory mechanisms that confer heterogeneity and complexity to DRD2 properties are not completely understood

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