E3 Ligase FBXW7 Facilitates Mycobacterium Immune Evasion by Modulating TNF-α Expression

Abstract

Tumor necrosis factor alpha (TNF-α) is a crucial factor in the control of Mycobacterium tuberculosis (Mtb) infection. Pathogenic mycobacteria can inhibit and/or regulate host cell TNF-α production in a variety of ways to evade antituberculosis (anti-TB) immunity as well as facilitate immune escape. However, the mechanisms by which TNF-α expression in host cells is modulated to the benefit of mycobacteria is still an interesting topic and needs further study. Here, we report that macrophages infected with Mycobacterium marinum (Mm)—a close relative of Mtb—upregulated the expression of E3 ubiquitin ligase FBXW7. Specific silencing FBXW7 with small interfering RNA (siRNA) significantly elevates TNF-α expression and eventually promotes the elimination of intracellular bacteria. In turn, overexpression of FBXW7 in Raw264.7 macrophages markedly decreased TNF-α production. Furthermore, partial inhibition of FBXW7 in an Mm-infected murine model significantly reduced TNF-α tissue content, alleviated tissue damage as well as reduced the bacterial load of mouse tails. Finally, FBXW7 could decrease TNF-α in a K63-linked ubiquitin signaling dependent manner. Taken together, our study uncovered a previously unknown role of FBXW7 in regulating TNF-α dynamics during mycobacterial infection, which provides new insights into understanding the role of FBXW7 in anti-tuberculosis immunity and its related clinical significance.

Pathogenic mycobacterium upregulates cholesterol 25-hydroxylase to promote granuloma development via foam cell formation

“…Mice were anesthetized by isoflurane and injected intravenously with indicated WT or ΔPDIM Mm in 100 μL of sterile PBS as previously described. 10 , 56 At indicated time-points, five mice from each group were humanely euthanized. Tails were cut into 5 mm pieces, ground with a mortar and homogenized in 3 mL DMEM supplemented with 0.1% Triton X-.…”

The structure and function of multifunctional protein ErbB3 binding protein 1 (Ebp1) and its role in diseases

“…P42 Ebp1 can also inhibit the tumorigenesis of cancer cells, metastasis of salivary gland adenoid carcinoma, and androgenmediated gene transcription (N. Oh et al, 2010; P42 Ebp1 increases the antitumor effect of FBXW7 via enhancement of its association with tumors and its carcinogenic targets such as c-Myc (Lan & Sun, 2019;Li et al, 2022). At the same time, p48 Ebp1 facilitates translocation of FBXW7 from the nucleus to the cytoplasm, where it cannot bind to its carcinogenic nuclear targets (Song et al, 2022;Wang et al, 2017;. The expression levels of p42 Ebp1 protein are significantly lower in the involved tissue than in the uninvolved tissues of GBM patients (C. K. Hwang et al, 2016;Kim et al, 2010).…”