The COMMD3/8 complex determines GRK6 specificity for chemoattractant receptors

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K19154
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Immunology
• Research Institution: Osaka University
• Principal Investigator: Akiko Nakai 大阪大学, 免疫学フロンティア研究センター, 特任研究員(常勤) (80768862)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 免疫応答 / GPCR / 走化性因子受容体 / 細胞遊走

Outline of Final Research Achievements

Lymphocyte migration is mediated by GPCRs that respond to chemoattractive molecules. After their activation, GPCRs are phosphorylated by different GRKs, which produces distinct functional outcomes through β-arrestins. However, the molecular machinery that targets individual GRKs to activated GPCRs remains elusive. Here, we identified copper metabolism MURR1 domain-containing (COMMD)8 as a protein that interacted with multiple chemoattractant receptors. COMMD8 was found to interact with COMMD3 of the same protein family (the COMMD3/8 complex). Deficiency of the COMMD8 or COMMD3 impaired B cell migration and humoral immune responses. We demonstrated that the COMMD3/8 complex selectively recruited GRK6 and induced GRK6-mediated phosphorylation of CXCR4 and activation of β-arrestin-mediated signaling. Thus, the COMMD3/8 complex functions as an adaptor that selectively recruits a specific GRK to chemoattractant receptors and represents a point of regulation for immune responses.

Free Research Field

免疫学

Academic Significance and Societal Importance of the Research Achievements

本研究において、COMMD3/8複合体がGRK6を走化性因子受容体に動員するアダプター分子として機能することが明らかになり、走化性因子受容体のシグナル伝達の新たな制御メカニズムが示された。また、B細胞特異的にCOMMD3/8複合体を欠損するマウスでは、B細胞を介した免疫応答が低下することが分かった。このことから、COMMD3/8複合体の機能を阻害することにより、過剰な免疫応答によって引き起こされる自己免疫疾患やその他の炎症性疾患の病態が改善する可能性が示された。今後、COMMD3/8複合体はこれらの疾患の治療における新たな創薬のターゲットになり得ると考えられる。