Dopamine Uses the DRD5-ARRB2-PP2A Signaling Axis to Block the TRAF6-Mediated NF-κB Pathway and Suppress Systemic Inflammation

Abstract

The functional relevance and mechanistic basis of the effects of the neurotransmitter dopamine (DA) on inflammation remain unclear. Here we reveal that DA inhibited TLR2-induced NF-κB activation and inflammation via the DRD5 receptor in macrophages. We found that the DRD5 receptor, via the EFD and IYX(X)I/L motifs in its CT and IC3 loop, respectively, can directly recruit TRAF6 and its negative regulator ARRB2 to form a multi-protein complex also containing downstream signaling proteins, such as TAK1, IKKs, and PP2A, that impairs TRAF6-mediated activation of NF-κB and expression of pro-inflammatory genes. Furthermore, the DA-DRD5-ARRB2-PP2A signaling axis can prevent S. aureus-induced inflammation and protect mice against S. aureus-induced sepsis and meningitis after DA treatment. Collectively, these findings provide the first demonstration of DA-DRD5 signaling acting to control inflammation and a detailed delineation of the underlying mechanism and identify the DRD5-ARRB2-PP2A axis as a potential target for future therapy of inflammation-associated diseases such as meningitis and sepsis.