ZDHHC9 promotes colon tumor growth by inhibiting effector T cells.

Zinc finger DHHC-type palmitoyltransferase 9 (ZDHHC9) has been reported to play an important role in the occurrence and development of several types of cancer. However, its effects on colon cancer growth remain unclear. Using Gene Expression Profiling Interactive Analysis and Tumor Immune Estimation Resource, data obtained from The Cancer Genome Atlas were analyzed, and the results showed that ZDHHC9 was highly expressed in colon cancer and that patients with higher ZDHHC9 expression levels had a worse prognosis. Inhibition of ZDHHC9 expression promoted the proliferation of colon cancer cells in vitro but decreased their growth in vivo. Additionally, inhibition of ZDHHC9 expression in cancer cells enhanced CD8+ T cell-mediated cytotoxicity in vitro and increased CD8+ T infiltration and activation in vivo. Furthermore, ZDHHC9 promoted IFN-γ-induced JAK/STAT1 activation and upregulated programmed death-ligand 1 (PD-L1) expression in colon cancer cells. In conclusion, the present findings showed that ZDHHC9 promoted colon cancer growth by upregulating the expression of PD-L1 and inhibiting the function of CD8+ T cells.

E3 ligase Nedd4l promotes antiviral innate immunity by catalyzing K29-linked cysteine ubiquitination of TRAF3.

Ubiquitination is one of the most prevalent protein posttranslational modifications. Here, we show that E3 ligase Nedd4l positively regulates antiviral immunity by catalyzing K29-linked cysteine ubiquitination of TRAF3. Deficiency of Nedd4l significantly impairs type I interferon and proinflammatory cytokine production induced by virus infection both in vitro and in vivo. Nedd4l deficiency inhibits virus-induced ubiquitination of TRAF3, the binding between TRAF3 and TBK1, and subsequent phosphorylation of TBK1 and IRF3. Nedd4l directly interacts with TRAF3 and catalyzes K29-linked ubiquitination of Cys56 and Cys124, two cysteines that constitute zinc fingers, resulting in enhanced association between TRAF3 and E3 ligases, cIAP1/2 and HECTD3, and also increased K48/K63-linked ubiquitination of TRAF3. Mutation of Cys56 and Cys124 diminishes Nedd4l-catalyzed K29-linked ubiquitination, but enhances association between TRAF3 and the E3 ligases, supporting Nedd4l promotes type I interferon production in response to virus by catalyzing ubiquitination of the cysteines in TRAF3.

TAOK1 positively regulates TLR4-induced inflammatory responses by promoting ERK1/2 activation in macrophages.

Thousand and one amino acid kinase 1 (TAOK1) is a member of Ste20-like kinases, but its function in regulating inflammatory responses remains largely unknown. In this study, we identify TAOK1 as a positive regulator of TLR4-triggered inflammatory responses in macrophages. TAOK1 increases LPS-induced production of pro-inflammatory cytokine such as IL-6, TNF-α and IL12p40 in macrophages. TAOK1 deficient mice showed decreased susceptibility to endotoxin shock, with less pro-inflammatory cytokine production than control mice. TAOK1 promotes LPS-induced activation of ERK1/2 by constitutively interacting with TRAF6 and TPL2. These finding unravel the important role of TAOK1 as a positive regulator of TLR4-induced inflammatory responses.

Transcription factor Fli-1 positively regulates lipopolysaccharide-induced interleukin-27 production in macrophages.

IL-27 is an important regulator of TLR4-activated innate immune. The mechanism by which IL-27 production is regulated in TLR4-activated innate immune remains largely unclear. Here we show that expression of transcription factor Fli-1 at protein level is increased in macrophages following LPS stimulation. Fli-1 overexpression increases LPS-activated IL-27 production in macrophages. Consistently, Fli-1 knockdown inhibits LPS-induced IL-27 production in macrophages. Chromatin immunoprecipitation (ChIP) assay reveals that Fli-1 binds the promoter of IL-27 p28 subunit. Further experiments manifest that Fli-1 binds the region between -250 and -150 bp upstream of the transcriptional start site of p28 gene and increases p28 gene promoter-controlled transcription. These results demonstrate that Fli-1 positively regulates IL-27 production in TLR4-activated immune response by promoting transcription of IL-27 p28 gene.