Drd2 biased agonist prevents neurodegeneration against NLRP3 inflammasome in Parkinson’s disease model via a β-arrestin2-biased mechanism

• Published in: Brain, behavior, and immunity behavior, and immunity, 2020-11, Vol.90, p.259-271
• Main Authors: Zhu, Jialei, Sun, Ting, Zhang, Jing, Liu, Yang, Wang, Dongshuo, Zhu, Hong, Yao, Hang, Ding, Jianhua, Hu, Gang, Lu, Ming
• Format: Article
• Language: English
• Subjects: Animals; Astrocyte; beta-Arrestin 1; Biased; Disease Models, Animal; Dopaminergic Neurons - metabolism; Drd2; Inflammasomes - metabolism; Mice; Mice, Inbred C57BL; MPTP Poisoning; NLR Family, Pyrin Domain-Containing 3 Protein - metabolism; Parkinson Disease; Parkinson’s disease; Receptors, Dopamine D2; UNC9995; β-Arrestin2
• ISSN: 0889-1591; 1090-2139
• DOI: 10.1016/j.bbi.2020.08.025

•UNC9995, a novel biased Drd2 agonist, rescued the TH+ neurons loss and inhibited glial cells activation in mouse substantia nigra in a Drd2 dependent manner.•UNC9995 shows a relatively safe concentration range and significantly suppresses astrocytic NLRP3 inflammasome activation induced by lipopolysaccharide plus ATP.•The anti-inflammatory effect of UNC9995 is independent of Drd2 / Gαi protein pathway, but activates β-arrestin2 by recruiting it to cell membrane.•UNC9995 enhances β-arrestin2 interacting with NLRP3 to interfere inflammasome assembly, which consequently reduces IL-1β production.•This work illustrates that Drd2 agonist UNC9995 prevents DA neuron degeneration in PD and provides a new strategy for targeting the β-arrestin2-biased ligands in the therapy of NDDs. Activated astrocytes secrete inflammatory cytokines such as interleukin-1β (IL-1β) into the extracellular milieu, damaging surrounding neurons and involving in the pathogenesis of neurodegenerative diseases, such as Parkinson’s disease (PD). Dopamine receptor D2 (Drd2) expresses both in neurons and astrocytes, and neuronal Drd2 is a significant target in therapy of PD. Our previous study reveals that astrocytic Drd2 exerts anti-inflammatory effect via non-classical β-arrestin2 signaling in PD model. Therefore, seeking new biased ligands of Drd2 with better efficacy and fewer side effects to treat PD is desirable and meaningful. In the present study, we evaluated the effects of UNC9995, a novel biased Drd2 agonist on astrocyte-derived neuroinflammation and dopaminergic (DA) neuron degenerationin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We showed that UNC9995 rescued the TH+ neurons loss and inhibited glial cells activation in mouse substantia nigra in a Drd2 dependent manner. Focusing on astrocytes, we found UNC9995 shows a relatively safe concentration range and significantly suppresses astrocytic NLRP3 inflammasome activation induced by lipopolysaccharide plus ATP. Further study revealed that the anti-inflammatory effect of UNC9995 is independent of Drd2 / Gαi protein pathway. It activates β-arrestin2 by recruiting it to cell membrane. Critically, UNC9995 enhances β-arrestin2 interacting with NLRP3 to interfere inflammasome assembly, which consequently reduces IL-1β production. On the other hand, UNC9995 inhibits IL-1β-induced inflammatory pathway activation in DA neurons and rescues subsequent apoptosis via β-arrestin2 interacting with protein kina