Regulation of p38MAPK-mediated dendritic cell functions by the deubiquitylase otubain 1

Partial otubain 1 deficiency compromises fetal well-being in allogeneic pregnancies despite no major changes in the dendritic cell and T cell compartment

Objective

Pregnancy is characterized by well-defined immunological adaptions within the maternal immune cell compartment allowing the survival of a genetically disparate individual in the maternal womb. Phenotype and function of immune cells are largely determined by intracellular processing of external stimuli. Ubiquitinating and deubiquitinating enzymes are known to critically regulate immune signaling either by modulating the stability or the interaction of the signaling molecules. Accordingly, if absent, critical physiological processes may be perturbed such as fetal tolerance induction. Based on previous findings that mice hemizygous for the deubiquitinating enzyme otubain 1 (OTUB1) do not give rise to homozygous progeny, here, we investigated whether partial OTUB1 deficiency influences fetal-wellbeing in a syngeneic or an allogeneic pregnancy context accompanied by changes in the dendritic cell (DC) and T cell compartment.

Results

We observed increased fetal rejection rates in allogeneic pregnant OTUB1 heterozygous dams but not syngeneic pregnant OTUB1 heterozygous dams when compared to OTUB1 wildtype dams. Fetal demise in allogeneic pregnancies was not associated with major changes in maternal peripheral and local DC and T cell frequencies. Thus, our results suggest that OTUB1 confers fetal protection, however, this phenotype is independent of immune responses involving DC and T cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-06230-w.

Immune-regulating strategy against rheumatoid arthritis by inducing tolerogenic dendritic cells with modified zinc peroxide nanoparticles

In hypoxic dendritic cells (DCs), a low level of Zn²⁺ can induce the activation of immunogenic DCs (igDCs), thereby triggering an active T-cell response to propel the immune progression of rheumatoid arthritis (RA). This finding indicates the crucial roles of zinc and oxygen homeostasis in DCs during the pathogenesis of RA. However, very few studies have focused on the modulation of zinc and oxygen homeostasis in DCs during RA treatment. Proposed herein is a DC-targeting immune-regulating strategy to induce igDCs into tolerogenic DCs (tDCs) and inhibit subsequent T-cell activation, referred to as ZnO₂/Catalase@liposome-Mannose nanoparticles (ZnCM NPs). ZnCM NPs displayed targeted intracellular delivery of Zn²⁺ and O₂ towards igDCs in a pH-responsive manner. After inactivating OTUB1 deubiquitination, the ZnCM NPs promoted CCL5 degradation via NF-κB signalling, thereby inducing the igDC-tDC transition to further inhibit CD4⁺ T-cell homeostasis. In collagen-induced arthritis (CIA) mice, this nanoimmunoplatform showed significant accumulation in the spleen, where immature DCs (imDCs) differentiated into igDCs. Splenic tDCs were induced to alleviate ankle swelling, improve walking posture and safely inhibit ankle/spleen inflammation. Our work pioneers the combination of DC-targeting nanoplatforms with RA treatments and highlights the significance of zinc and oxygen homeostasis for the immunoregulation of RA by inducing tDCs with modified ZnO₂ NPs, which provides novel insight into ion homeostasis regulation for the treatment of immune diseases with a larger variety of distinct metal or nonmetal ions.

The DC-targeting immune-regulating nanostrategy was firstly employed to treat RA.

The complex immune regulating effects was realized through a portable, convenient and green nanomaterial.

Highlighting the significance of zinc and oxygen homeostasis for the immunoregulation of RA by inducing tDCs with modified ZnO₂ NPs.

Expanding the notion of ion homeostasis regulation with a larger variety of distinct metal or nonmetal ions.

OTUB1 alleviates NASH through inhibition of the TRAF6-ASK1 signaling pathways

BACKGROUND AND AIMS

NAFLD is considered as the hepatic manifestation of the metabolic syndrome, which includes insulin resistance, obesity and hyperlipidemia. NASH is a progressive stage of NAFLD with severe hepatic steatosis, hepatocyte death, inflammation, and fibrosis. Currently, no pharmacological interventions specifically tailored for NASH are approved. Ovarian tumor domain, ubiquitin aldehyde binding 1 (OTUB1), the founding member of deubiquitinases, regulates many metabolism-associated signaling pathways. However, the role of OTUB1 in NASH is unclarified.

METHODS AND RESULTS

We demonstrated that mice with Otub1 deficiency exhibited aggravated high-fat diet-induced and high-fat high-cholesterol (HFHC) diet-induced hyperinsulinemia and liver steatosis. Notably, hepatocyte-specific overexpression of Otub1 markedly alleviated HFHC diet-induced hepatic steatosis, inflammatory responses, and liver fibrosis. Mechanistically, we identified apoptosis signal-regulating kinase 1 (ASK1) as a key candidate target of OTUB1 through RNA-sequencing analysis and immunoblot analysis. Through immunoprecipitation-mass spectrometry analysis, we further found that OTUB1 directly bound to tumor necrosis factor receptor-associated factor 6 (TRAF6) and suppressed its lysine 63-linked polyubiquitination, thus inhibiting the activation of ASK1 and its downstream pathway.

CONCLUSIONS

OTUB1 is a key suppressor of NASH that inhibits polyubiquitinations of TRAF6 and attenuated TRAF6-mediated ASK1 activation. Targeting the OTUB1-TRAF6-ASK1 axis may be a promising therapeutic strategy for NASH.

Deubiquitinating enzyme OTUB1 in immunity and cancer: Good player or bad actor?

OTU domain-containing ubiquitin aldehyde-binding proteins 1 (OTUB1) is the most important element of the deubiquitinase OTU superfamily, which has been identified as an essential regulator of diverse physiological processes, such as DNA damage repair and cytokines secretion. Recently, we found that the pro-carcinogenesis role of OTUB1 and the relationship between OTUB1 and immune response have gradually become the research hot-spot. OTUB1 regulates NK/CD8 T cell activation, autoimmune diseases, PD-L1 mediated immune evasion, viral or bacterial infection related immune response and the occurrence and progression of various cancers via deubiquitinating and stabilizing related proteins. This review provides a comprehensive description about the role and regulatory axis of OTUB1. We can explore the balance between immune response and defense via regulating the level of OTUB1, and targeting OTUB1 might restrain the progression of cancers. This review highlights the experimental evidence that OTUB1 is a feasible and potential therapeutic target against various cancers progression and immune diseases or disorder.

Molecular Mechanisms of DUBs Regulation in Signaling and Disease

The large family of deubiquitinating enzymes (DUBs) are involved in the regulation of a plethora of processes carried out inside the cell by protein ubiquitination. Ubiquitination is a basic pathway responsible for the correct protein homeostasis in the cell, which could regulate the fate of proteins through the ubiquitin–proteasome system (UPS). In this review we will focus on recent advances on the molecular mechanisms and specificities found for some types of DUBs enzymes, highlighting illustrative examples in which the regulatory mechanism for DUBs has been understood in depth at the molecular level by structural biology. DUB proteases are responsible for cleavage and regulation of the multiple types of ubiquitin linkages that can be synthesized inside the cell, known as the ubiquitin-code, which are tightly connected to specific substrate functions. We will display some strategies carried out by members of different DUB families to provide specificity on the cleavage of particular ubiquitin linkages. Finally, we will also discuss recent progress made for the development of drug compounds targeting DUB proteases, which are usually correlated to the progress of many pathologies such as cancer and neurodegenerative diseases.

Regulation of cell activation by A20 through STAT signaling in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the hematologic malignancy characterized by the aberrant proliferation of immature lymphoid cells. A20 is a deubiquitinase gene that inhibits functional activation of immune cells mediated through NF-κB/STAT pathways and frequently found inactivated in lymphoma. IL-6 is a pro-inflammatory cytokine secreted by immune cells under the pathogenic conditions and regulated by STAT signaling. Little is known about the role of A20 in regulating the function of ALL blasts and underlying molecular mechanisms. The present study, therefore, explored whether A20 expression contributes to IL-6 induced cell migration and activation of myeloid cells in ALL. To this end, blood samples of thirty-five adult ALL patients were examined. Gene expression profile was determined by quantitative RT-PCR, immunophenotype by flow cytometry, secretion of inflammatory cytokines by ELISA, and cell migration by a transwell migration assay. As a result, the expression of A20 was inactivated in ALL. Immunophenotypic analysis indicated that percent of CD11b⁺CD40⁺ expressing cells present in ALL was significantly reduced when transfected with PEM-T easy A20. Importantly, IL6-induced CXCL12-mediated migration of ALL blasts was dependent on the presence of A20. The inhibitory effects of A20 on activated myeloid cells and migration of ALL blasts were mediated through the STAT pathway upon IL-6 challenge. In addition, the CA-125 level was much higher in elderly females than either young female or male ALL patients or healthy donors. In conclusion, the inhibitory effects of A20 on activation of ALL blasts are expected to affect the immune response to treatment for adult ALL patients.