N4BP1 negatively regulates NF-κB by binding and inhibiting NEMO oligomerization

Abstract

Many immune responses depend upon activation of NF-κB, an important transcription factor in the elicitation of a cytokine response. Here we show that N4BP1 inhibits TLR-dependent activation of NF-κB by interacting with the NF-κB signaling essential modulator (NEMO, also known as IκB kinase γ) to attenuate NEMO–NEMO dimerization or oligomerization. The UBA-like (ubiquitin associated-like) and CUE-like (ubiquitin conjugation to ER degradation-like) domains in N4BP1 mediate interaction with the NEMO COZI domain. Both in vitro and in mice, N4bp1 deficiency specifically enhances TRIF-independent (TLR2, TLR7, or TLR9-mediated) but not TRIF-dependent (TLR3 or TLR4-mediated) NF-κB activation, leading to increased production of proinflammatory cytokines. In response to TLR4 or TLR3 activation, TRIF causes activation of caspase-8, which cleaves N4BP1 distal to residues D424 and D490 and abolishes its inhibitory effect. N4bp1−/− mice also have diminished numbers of T cells in the peripheral blood. Our work identifies N4BP1 as an inhibitory checkpoint protein that must be overcome to activate NF-κB, and a TRIF-initiated caspase-8-dependent mechanism by which this is accomplished.

Regnase‐1–related endoribonucleases in health and immunological diseases

“…A report showed that N4BP1 inhibits TLR-mediated activation of NF-κB by interacting with the NF-κB signaling essential modulator (NEMO, also known as IκB kinase γ) to suppress NEMO dimerization. 119 In this scenario, the RNase domain of N4BP1 is not required for the control of NF-κB in macrophages. Another study showed that N4BP1 is expressed in the skin and further upregulated during psoriasis.…”

“…N4BP1 inhibits replication of HIV-1 and lentiviruses in T cells and macro- Recent studies demonstrate that N4BP1 participates in the regulation of host innate immune responses. 118,119 N4bp1 −/− mice develop mild inflammation and have exacerbated TLR-dependent inflammatory responses. 118 These mice also show diminished numbers of T cells in the peripheral blood.…”

“…118 These mice also show diminished numbers of T cells in the peripheral blood. 119 N4BP1 has also been shown to suppresses cytokine production induced by TLRs in macrophages.…”

The Effects of Adoptively Transferred IL-23/IL-18-Polarized Neutrophils on Tumor and Collagen-Induced Arthritis in Mice

“…The purified mouse or human neutrophils were adjusted to 1×10 6 cells/mL and added into 48 well plates. The cells were cultured with cytokines or inhibitors according to the following concentrations: [17][18][19][20][21][22][23][24] rmIL-1β (100 ng/mL), rmIL-4 (10 ng/mL), rmIL-6 (50 ng/mL), rmIL-10 (20 ng/ mL), rmIL-13 (50 ng/mL), rmIL-21 (50 ng/mL), rmIL-33 (100 ng/mL), LPS (100 ng/mL), rmIFN-γ (100 ng/mL), rmTNF-α (100 ng/mL), rmTGF-β1 (5 ng/mL), rmGM-CSF (40 ng/mL), rmG-CSF (100 ng/mL), rmIL-2 (10 ng/ mL). rmIL-12 (5 ng/mL), IL-17A (100 ng/mL), rmIL-18 (25 ng/mL), rmIL-25 (20ng/mL), JNK inhibitor (SP600125, 10 or 20 μM), A selective ERK inhibitor (PD98059, 10 or 20 μM), NF-κB inhibitor (10 or 20 μM), and P38 inhibitor (SB203580, 10 or 20 μM).…”

TSG101 Associates with PARP1 and is Essential for PARylation and DNA Damage-induced NF-κB Activation

“…C: Z-scores of the best-scoring siRNAs for selected previously known and newly identified pathway regulators. Hits include VPS28 (Mamińska et al, 2016), CYLD (Trompouki et al, 2003), NFKBIA (Haskill et al, 1991), TRAF3 (Vallabhapurapu et al, 2008), N4BP1 (Shi et al, 2021), TANK (Wang et al, 2015), SENP1 (Lee et al, 2011;Shao et al, 2015), PARG (Cortes et al, 2004), RELA (Li et al, 2001), TIFA (Fu et al, 2018), CHUK (Colomer et al, 2019), TRAF6 (Hinz et al, 2010) and IKBKG (Mabb et al, 2006) for expected factors. D: Representative relative luciferase units (RLU) of the differential counter screen of the 320 pre-selected hits are shown.…”