Ubiquitination and degradation of NF90 by Tim-3 inhibits antiviral innate immunity

Trim47 prevents hematopoietic stem cell exhaustion during stress by regulating MAVS-mediated innate immune pathway

The maintenance of hematopoietic stem cell (HSC) functional integrity is essential for effective hematopoietic regeneration when suffering from injuries. Studies have shown that the innate immune pathways play crucial roles in the stress response of HSCs, whereas how to precisely modulate these pathways is not well characterized. Here, we identify the E3 ubiquitin ligase tripartite motif-containing 47 (Trim47) as a negative regulator of the mitochondrial antiviral-signaling protein (MAVS)-mediated innate immune pathway in HSCs. We find that Trim47 is predominantly enriched in HSCs, and its deficiency impairs the function and survival of HSCs after exposure to 5-flurouracil (5-FU) and irradiation (IR). Mechanistically, Trim47 impedes the excessive activation of the innate immune signaling and inflammatory response via K48-linked ubiquitination and degradation of MAVS. Collectively, our findings demonstrate a role of Trim47 in preventing stress-induced hematopoietic failure and thus provide a promising avenue for treatment of related diseases in the clinic.

Emerging roles of tripartite motif family proteins (TRIMs) in breast cancer

Breast cancer (BC) is the most common malignant tumor worldwide. Despite enormous progress made in the past decades, the underlying mechanisms of BC remain further illustrated. Recently, TRIM family proteins proved to be engaged in BC progression through regulating various aspects. Here we reviewed the structures and basic functions of TRIM family members and first classified them into three groups according to canonical polyubiquitination forms that they could mediate: K48- only, K63- only, and both K48- and K63-linked ubiquitination. Afterwards, we focused on the specific biological functions and mechanisms of TRIMs in BCs, including tumorigenesis and invasiveness, drug sensitivity, tumor immune microenvironment (TIME), cell cycle, and metabolic reprogramming. We also explored the potential of TRIMs as novel biomarkers for predicting prognosis and future therapeutic targets in BC.

Porcine TLR8 signaling and its anti-infection function are disturbed by immune checkpoint receptor TIM-3 via inhibition of P13K-AKT pathway

Toll-like receptor 8 (TLR8), an important innate immune receptor recognizing single stranded RNA and the antiviral imidazoquinoline compounds, can activate intracellular signaling pathway and produce an inflammatory response to kill and eliminate pathogens. However, the molecular regulation mechanisms of TLR8 signaling and its anti-infection activity are not fully elucidated. Our previous transcriptome analysis of porcine TLR8 (pTLR8) signaling suggested the immune checkpoint receptor TIM-3 as the potential regulator for pTLR8. Here we investigated TIM-3 in the regulation of pTLR8 signaling and its anti-infection activity. Our results showed that porcine TIM-3 is upregulated by pTLR8 signaling and TIM-3 inhibits pTLR8 signaling activity in a negative feedback way. Accordingly, TIM-3 disturbs pTLR8 mediated anti-bacterial and anti-viral activity. Mechanistically, TIM-3 suppresses PI3K-AKT pathway by inhibiting the TLR8-PI3K p85 interaction and subsequent AKT phosphorylation which is essential for TLR8 signaling and anti-infection activity. Therefore, our study reveals new insights into innate immune TLR8 signaling and its anti-infection function.

ADAM17 variant causes hair loss via ubiquitin ligase TRIM47-mediated degradation

Hypotrichosis is a genetic disorder characterized by a diffuse and progressive loss of scalp and/or body hair. Nonetheless, the causative genes for several affected individuals remain elusive, and the underlying mechanisms have yet to be fully elucidated. Here, we discovered a dominant variant in a disintegrin and a metalloproteinase domain 17 (ADAM17) gene caused hypotrichosis with woolly hair. Adam17 (p.D647N) knockin mice mimicked the hair abnormality in patients. ADAM17 (p.D647N) mutation led to hair follicle stem cell (HFSC) exhaustion and caused abnormal hair follicles, ultimately resulting in alopecia. Mechanistic studies revealed that ADAM17 binds directly to E3 ubiquitin ligase tripartite motif-containing protein 47 (TRIM47). ADAM17 variant enhanced the association between ADAM17 and TRIM47, leading to an increase in ubiquitination and subsequent degradation of ADAM17 protein. Furthermore, reduced ADAM17 protein expression affected the Notch signaling pathway, impairing the activation, proliferation, and differentiation of HFSCs during hair follicle regeneration. Overexpression of Notch intracellular domain rescued the reduced proliferation ability caused by Adam17 variant in primary fibroblast cells.

5-HT7R enhances neuroimmune resilience and alleviates meningitis by promoting CCR5 ubiquitination

INTRODUCTION

Excessive immune activation induces tissue damage during infection. Compared to external strategies to reconstruct immune homeostasis, host balancing ways remain largely unclear.

OBJECTIVES

Here we found a neuroimmune way that prevents infection-induced tissue damage.

METHODS

By FACS and histopathology analysis of brain Streptococcus pneumonia meningitis infection model and behavioral testing. Western blot, co-immunoprecipitation, and ubiquitination analyze the Fluoxetine initiate 5-HT7R-STUB1-CCR5 K48-linked ubiquitination degradation.

RESULTS

Fluoxetine, a selective serotonin reuptake inhibitor, or the agonist of serotonin receptor 5-HT7R, protects mice from meningitis by inhibiting CCR5-mediated excessive immune response and tissue damage. Mechanistically, the Fluoxetine-5-HT7R axis induces proteasome-dependent degradation of CCR5 via mTOR signaling, and then recruits STUB1, an E3 ubiquitin ligase, to initiate K48-linked polyubiquitination of CCR5 at K138 and K322, promotes its proteasomal degradation. STUB1 deficiency blocks 5-HT7R-mediated CCR5 degradation.

CONCLUSION

Our results reveal a neuroimmune pathway that balances anti-infection immunity via happiness neurotransmitter receptor and suggest the 5-HT7R-CCR5 axis as a potential target to promote neuroimmune resilience.

Tim-3 deficiency aggravates cadmium nephrotoxicity via regulation of NF-κB signaling and mitochondrial damage

Kidney is the target organ of serious cadmium injury. Kidney damage caused by cadmium exposure is greatly influenced by the inflammatory response and mitochondrial damage. T cell immunoglobulin domain and mucin domain 3 (Tim-3) is an essential protein that functions as a negative immunological checkpoint to regulate inflammatory responses. Mice were given cadmium treatments at various dosages (0, 1.5, 3, 4.5 mg/kg) and times (0, 3, 5, 7 days) to assess the effects of cadmium on kidney damage. We found that the optimal way to induce kidney injury in mice was to inject 4.5 mg/kg of cadmium intraperitoneally for five days. It is interesting that giving mice 4.5 mg/kg of cadmium intravenously for seven days drastically lowered their survival rate. After cadmium exposure, Tim-3 knockout mice exhibited higher blood concentrations of urea nitrogen and creatinine compared to control mice. Tim-3 impacted the expression of oxidative stress-associated genes such as UDP glucuronosyltransferase family 1 member A9 (Ugt1a9), oxidative stress-induced growth inhibitor 2 (Osgin2), and S100 calcium binding protein A8 (S100a8), according to RNA-seq and real-time RT-PCR data. Tim-3 deficiency also resulted in activated nuclear factor-kappa B (NF-κB) signaling pathway. The NF-κB inhibitor 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1) significantly alleviated cell apoptosis, oxidative stress response, and renal tubule inflammation in Tim-3 knockout mice exposed to cadmium. Furthermore, cadmium caused obvious B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax) translocation from cytoplasm to mitochondria, which can be inhibited by TPCA-1. In conclusion, Tim-3 prevented mitochondrial damage and NF-κB signaling activation, hence providing protection against cadmium nephrotoxicity.

Featured interactome of homocysteine-inducible endoplasmic reticulum protein uncovers novel binding partners in response to ER stress

Homocysteine-inducible endoplasmic reticulum protein (HERP) is an endoplasmic reticulum (ER)-resident protein and important for the adaptation of cellular protein homeostasis by ER-associated degradation (ERAD) system. HERP interactors are critical for cellular viability and the reaction to ER stress. To explore the exact mechanisms by which HERP performed the biological functions, we conducted an interaction analysis of HERP protein in HeLa cells by co-immunoprecipitation (Co-IP) and liquid chromatography-mass spectrometer (LC-MS)/MS coupled with label-free quantification (LFQ). Among the interactome results, 123 proteins significantly interacted with HERP, which leads to numerous biological processes including protein import into nucleus, ubiquitin-dependent ERAD pathway, negative regulation of apoptotic process, and protein transport from ER, along with multiple pathways including several diseases, protein processing in ER, fatty acid metabolism, and steroid biosynthesis. Furthermore, we selected several prey proteins from the interactome data and confirmed that HERP interacted with ancient ubiquitous protein 1 (AUP1), Fas-associated factor family member 2 (FAF2), tripartite motif containing 47 (TRIM47), acyl-CoA synthetase long-chain family member 3 (ACSL3), sequestosome 1 (SQSTM1), and poly(rC) binding protein 2 (PCBP2) by Co-IP and confocal microscopy experiments, respectively. Moreover, the expression and location of several interacted proteins were obviously altered in response to ER stress induced by Thapsigargin stimulation and Enterovirus 71 infection. In conclusion, our findings revealed that the vital proteins interacted with HERP to mediate signaling transduction, thus providing novel clues for the mechanisms of HERP associated with ERAD and metabolism in response to ER stress under physiological and pathological conditions.

Tim-3 protects against cisplatin nephrotoxicity by inhibiting NF-κB-mediated inflammation

The impact of Tim-3 (T cell immunoglobulin and mucin domain-containing protein 3) on cisplatin-induced acute kidney injury was investigated in this study. Cisplatin-induced Tim-3 expression in mice kidney tissues and proximal tubule-derived BUMPT cells in a time-dependent manner. Compared with wild-type mice, Tim-3 knockout mice have higher levels of serum creatinine and urea nitrogen, enhanced TUNEL staining signals, more severe 8-OHdG (8-hydroxy-2' -deoxyguanosine) accumulation, and increased cleavage of caspase 3. The purified soluble Tim-3 (sTim-3) protein was used to intervene in cisplatin-stimulated BUMPT cells by competitively binding to the Tim-3 ligand. sTim-3 obviously increased the cisplatin-induced cell apoptosis. Under cisplatin treatment conditions, Tim-3 knockout or sTim-3 promoted the expression of TNF-α (tumor necrosis factor-alpha) and IL-1β (Interleukin-1 beta) and inhibited the expression of IL-10 (interleukin-10). NF-κB (nuclear factor kappa light chain enhancer of activated B cells) P65 inhibitor PDTC or TPCA1 lowed the increased levels of creatinine and BUN (blood urea nitrogen) in cisplatin-treated Tim-3 knockout mice serum and the increased cleavage of caspase 3 in sTim-3 and cisplatin-treated BUMPT cells. Moreover, sTim-3 enhanced mitochondrial oxidative stress in cisplatin-induced BUMPT cells, which can be mitigated by PDTC. These data indicate that Tim-3 may protect against renal injury by inhibiting NF-κB-mediated inflammation and oxidative stress.

Efp/TRIM25 and Its Related Protein, TRIM47, in Hormone-Dependent Cancers

Increasing attention has been paid to the biological roles of tripartite motif-containing (TRIM) family proteins, which typically function as E3 ubiquitin ligases. Estrogen-responsive finger protein (Efp), a member of the TRIM family proteins, also known as TRIM25, was originally identified as a protein induced by estrogen and plays critical roles in promoting endocrine-related cancers, including breast cancer, endometrial cancer, and prostate cancer. The pathophysiological importance of Efp made us interested in the roles of other TRIM family proteins that share a similar structure with Efp. Based on a phylogenetic analysis of the C-terminal region of TRIM family proteins, we focused on TRIM47 as a protein belonging to the same branch as Efp. TRIM47 is a poor prognostic factor in both breast cancer and prostate cancer. Atypical lysine-27-like poly-ubiquitination was involved in the underlying mechanism causing endocrine resistance in breast cancer. We also discuss the functions of Efp and TRIM47 in other types of cancers and innate immunity by introducing substrates the are modified by poly-ubiquitination.

Tim-3+ decidual Mφs induced Th2 and Treg bias in decidual CD4+T cells and promoted pregnancy maintenance via CD132

T-cell immunoglobulin mucin-3 (Tim-3) plays roles in the functional regulation of both adaptive and innate immune cells and is greatly involved in many diseases. However, the precise roles of Tim-3 on macrophages (Mφs) in pregnancy remain unstated. In the current study, we found the higher frequency of Tim-3⁺ decidual Mφs (dMφs) in response to trophoblasts. The reduced abundance of Tim-3 on Mφs was accompanied by disordered anti- and pro-inflammatory cytokine profiles in miscarriage. Adoptive transfer of Tim-3⁺Mφs, but not Tim-3^-Mφs, relieved murine embryo absorption induced by Mφ depletion. Our flow cytometry results and the extensive microarray analysis confirmed that Tim-3⁺ and Tim-3^-dMφs were neither precisely pro-inflammatory (M1) nor anti-inflammatory (M2) Mφs. However, with higher CD132 expression, Tim-3⁺dMφs subset induced Th2 and Treg bias in decidual CD4⁺T cells and promoted pregnancy maintenance. Blockade of Tim-3 or CD132 pathways leaded to the dysfunction of maternal-fetal tolerance and increased fetal loss. These findings underscored the important roles of Tim-3 in regulating dMφ function and maintaining normal pregnancy, and suggested that Tim-3 on Mφs is a potential biomarker for diagnosis of miscarriage. Our study also emphasized the importance of careful consideration of reproductive safety when choosing immune checkpoint blockade therapies in real world clinical care. Though IL-4 treated Tim-3^-Mφs could rescue the fetal resorption induced by Mφ depletion, whether IL-4 represent novel therapeutic strategy to prevent pregnancy loss induced by checkpoint inhibition still needs further research.

TRIM47 is a novel endothelial activation factor that aggravates lipopolysaccharide-induced acute lung injury in mice via K63-linked ubiquitination of TRAF2

Endothelial activation plays an essential role in the pathogenesis of sepsis-induced acute lung injury, however, the detailed regulatory mechanisms remain largely unknown. Here, we reported that TRIM47, an E3 ubiquitin ligase of the tripartite motif-containing protein family, was highly expressed in vascular endothelial cells. TRIM47-deficient mice were effectively resistant to lipopolysaccharide (LPS)-induced acute lung injury and death by attenuating pulmonary inflammation. TRIM47 was upregulated during TNFα-induced endothelial activation in vitro. Knockdown of TRIM47 in endothelial cells inhibited the transcription of multiple pro-inflammatory cytokines, reduced monocyte adhesion and the expression of adhesion molecules, and suppressed the secretion of IL-1β and IL-6 in endothelial cells. By contrast, overexpression of TRIM47 promoted inflammatory response and monocyte adhesion upon TNFα stimulation. In addition, TRIM47 was able to activate the NF-κB and MAPK signaling pathways during endothelial activation. Furthermore, our experiments revealed that TRIM47 resulted in endothelial activation by promoting the K63-linked ubiquitination of TRAF2, a key component of the TNFα signaling pathway. Taken together, our studies demonstrated that TRIM47 as a novel activator of endothelial cells, promoted LPS-induced pulmonary inflammation and acute lung injury through potentiating the K63-linked ubiquitination of TRAF2, which in turn activates NF-κB and MAPK signaling pathways to trigger an inflammatory response in endothelial cells.