CARMA3 deficiency abrogates G protein-coupled receptor-induced NF-κB activation

Abstract

G protein-coupled receptors (GPCRs) play pivotal roles in regulating various cellular functions. Although many GPCRs induce NF-B activation, the molecular mechanism of GPCR-induced NF-B activation remains largely unknown. CARMA3 (CARD and MAGUK domain-containing protein 3) is a scaffold molecule with unknown biological functions. By generating CARMA3 knockout mice using the gene targeting approach, here we show CARMA3 is required for GPCR-induced NF-B activation. Mechanistically, we found that CARMA3 deficiency impairs GPCR-induced IB kinase (IKK) activation, although it does not affect GPCR-induced IKK␣/␤ phosphorylation, indicating that inducible phosphorylation of IKK␣/␤ alone is not sufficient to induce its kinase activity. We also found that CARMA3 is physically associated with NEMO/IKK␥, and induces polyubiquitination of an unknown protein(s) that associates with NEMO, likely by linking NEMO to TRAF6. Consistently, we found TRAF6 deficiency also abrogates GPCR-induced NF-B activation. Together, our results provide the genetic evidence that CARMA3 is required for GPCR-induced NF-B activation.[Keywords: NF-B; GPCR; CARMA3; neural tube] Supplemental material is available at http://www.genesdev.org.

NF-κB signaling pathways regulated by CARMA family of scaffold proteins

“…Similar defect is observed following stimulation with other GPCR ligands, such as endothelin-1 and angiotensin-II, in the absence of CARMA3 [123,128,129]. Importantly, CARMA3 is specifically required for GP-CR-induced IKK activity because CARMA3 deficiency does not affect IKK activation by other stimuli such as TNFα and lipopolysaccharide (LPS) [123].…”

“…www.cell-research.com | Cell Research Marzenna Blonska and Xin Lin 63 npg production in mouse embryonic fibroblasts (MEF) [123]. Similar defect is observed following stimulation with other GPCR ligands, such as endothelin-1 and angiotensin-II, in the absence of CARMA3 [123,128,129].…”

“…CARMA3 is expressed widely in non-hematopoietic cells and has recently been described as a link between G protein-coupled receptors (GPCRs) and NF-κB [123]. GPCR is the largest class of transmembrane receptors in the human genome involved in regulation of proliferation, differentiation, and immune response through the wide variety of its ligands [124].…”

Role of G protein-coupled receptors in inflammation

“…Upon GPCR activation, β-arrestins participate in intracellular signaling leading to activation of multiple pathways that favor NF-κB activation [82][83][84] . Several intracellular signaling molecules that were initially identified for immune cell functions, including CARMA3 and Bcl10, were found to regulate GPCR signaling leading to NF-κB activation [85,86] . These latter findings provide evidence for the complexity of signaling pathways downstream of GPCRs.…”

Molecular pathogenesis of lymphomas of mucosa-associated lymphoid tissue—from (auto)antigen driven selection to the activation of NF-κB signaling

“…CARMA1/ CARD11, CARMA2/CARD14 and CARMA3/CARD10 are highly conserved across species, sharing a similar structure but expressed in a tissue-specific pattern [80][81][82]. Upon the activation of T cell receptor (TCR), protein kinase C- (PKC) is recruited by CARMA1, and the activated PKC subsequently phosphorylates CARMA1 to recruit Bcl-10 and MALT1, thus promoting TCR-induced NF-B signaling [83].…”