TRIM35 mediates protection against influenza infection by activating TRAF3 and degrading viral PB2

Tripartite motif (TRIM) family proteins are important effectors of innate immunity against viral infections. Here we identified TRIM35 as a regulator of TRAF3 activation. Deficiency in or inhibition of TRIM35 suppressed the production of type I interferon (IFN) in response to viral infection. Trim35-deficient mice were more susceptible to influenza A virus (IAV) infection than were wild-type mice. TRIM35 promoted the RIG-I-mediated signaling by catalyzing Lys63-linked polyubiquitination of TRAF3 and the subsequent formation of a signaling complex with VISA and TBK1. IAV PB2 polymerase countered the innate antiviral immune response by impeding the Lys63-linked polyubiquitination and activation of TRAF3. TRIM35 mediated Lys48-linked polyubiquitination and proteasomal degradation of IAV PB2, thereby antagonizing its suppression of TRAF3 activation. Our in vitro and in vivo findings thus reveal novel roles of TRIM35, through catalyzing Lys63- or Lys48-linked polyubiquitination, in RIG-I antiviral immunity and mechanism of defense against IAV infection.

miR-29b-3p promotes progression of MDA-mB-231 triple-negative breast cancer cells through downregulating TRAF3

BACKGROUND: Breast cancer is the second common malignant cancer among females worldwide. Accumulating studies have indicated that deregulation of miRNA expression in breast cancer will contribute to tumorigenesis and form different cancer subtypes. However, the reported studies on miR-29b-3p-regulated breast cancer are limited so far. Herein, we investigated the role and mechanism of miR-29b-3p in the triple negative breast cancer cell line MDA-MB-231. METHODS: The relative miR-29b-3p expression in different breast cancer cell lines were determined by qRT-PCR. CCK8 and colony formation assay were used to determine the influence of miR-29b-3p on cell proliferation. Migration assay and invasion assay were performed for cell migration and invasion respectively. To study the cell integrity immunofluorescence was performed. TUNEL assay, flow cytometry assay, hoechst staining and western blot were conducted to determine the influence of miR-29b-3p inhibitor on cell apoptosis. TRAF3 was found to be the target gene of miR-29b-3p using bioinformatics predictions. Dual-luciferase assay was performed to determine the relative luciferase activity in NC, miR-29b-3p mimic, miR-29b-3p inhibitor with TRAF3 3'-UTR wt or TRAF3 3'-UTR mt reporter plasmids. The proteins expression of NF-κB signaling pathway in MDA-MB-231 after transfection with NC, miR-29b-3p mimic, miR-29b-3p inhibitor were determined by western blot. RESULTS: The miR-29b-3p expression was significantly increased in MDA-MB-231 compare with MCF-10A. miR-29b-3p inhibitor reduced the cell viability of MDA-MB-231 and inhibited cell migration and invasion. Cell cytoskeleton integrity destroyed after miR-29b-3p inhibitor treatment. Furthermore, we identified the mechanism and found miR-29b-3p targets the TRAF3 and activates NF-κB signaling pathway. CONCLUSIONS: From the above studies, our results indicated that miR-29b-3p acts as a promoter for the development of MDA-MB-231.

Role of Pellino-1 Overexpression on Ubiquitin of Tumor Necrosis Factor Receptor-associated Factors 3 and MAPK Signaling Pathway in Endotoxin-tolerant Kupffer Cells / 中山大学学报(医学科学版)

[Objective]To investigate the effect of pellino-1 gene overexpression by lentivirus vector on the ubiquitin of tumor necrosis factor receptor-associated factors 3 (TRAF3) and the activation of mitogen-activated protein kinases (MAPK) signaling pathway in endotoxin-tolerant kupffer cells (KCs).[Methods]Isolated KCs of C57BL/6 mouse were randomly divided into two groups:control group,which transfected with control lentivirus vector for 48 h,then pretreated with 10 ng/mL lipopolysaccharide (LPS)for 24 h,and next treated with 300 ng/mL LPS;overexpression group,which transfected with pellino-1 gene overexpression lentivirus vector for 48 h,then pretreated with 10 ng/mL lipopolysaccharide(LPS)for 24 h,and next treated with 300 ng/mL LPS. The protein expressions of pellino-1,K48-Ub,TRAF3,p38,p-p38,c-Jun N-terminal kinase(JNK)and p-JNK were analyzed by Western blot. The level of interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α)and interleukin-10(IL-10)in superna-tants were measured by enzyme linked immunosorbent assay(ELISA).[Results]Compared with control group,the protein expres-sions of pellino-1,K48-Ub,p-JNK and p-p38 and the levels of IL-1β(P < 0.05),TNF-α(P < 0.05)in supernatants was in-creased in overexpression group,while the protein levels of TRAF3 and the levels of IL-10(P < 0.05)in supernatants were de-creased.[Conclusion]Overexpression of pellino-1 can promote TRAF3 K48 ubiquitination degradation,decrease the protein expres-sion of TRAF3,activate the downstream MAPK signaling pathway,and thus impair the formulation of endotoxin tolerance.

Differential Signaling via Tumor Necrosis Factor-Associated Factors (TRAFs) by CD27 and CD40 in Mouse B Cells

BACKGROUND: CD27 is recently known as a memory B cell marker and is mainly expressed in activated T cells, some B cell population and NK cells. CD27 is a member of tumor necrosis factor receptor family. Like CD40 molecule, CD27 has (P/S/T/A) X(Q/E)E motif for interacting with TNF receptor-associated factors (TRAFs), and TRAF2 and TRAF5 bindings to CD27 in 293T cells were reported. METHODS: To investigate the CD27 signaling effect in B cells, human CD40 extracellular domain containing mouse CD27 cytoplamic domain construct (hCD40-mCD27) was transfected into mouse B cell line CH12.LX and M12.4.1. RESULTS: Through the stimulation of hCD40-mCD27 molecule via anti-human CD40 antibody or CD154 ligation, expression of CD11a, CD23, CD54, CD70 and CD80 were increased and secretion of IgM was induced, which were comparable to the effect of CD40 stimulation. TRAF2 and TRAF3 were recruited into lipid-enriched membrane raft and were bound to CD27 in M12.4.1 cells. CD27 stimulation, however, did not increase TRAF2 or TRAF3 degradation. CONCLUSION: In contrast to CD40 signaling pathway, TRAF2 and TRAF3 degradation was not observed after CD27 stimulation and it might contribute to prolonged B cell activation through CD27 signaling.