There are several emerging strategies for the vaccination of COVID-19 (SARS-CoV-2) however, only a few have yet shown promising effects. Thus, choosing the right pathway and the best prophylactic ...options in preventing COVID-19 is still challenging at best. Approximately, more than two-hundred vaccines are being tested in different countries, and more than fifty clinical trials are currently undergoing. In this review, we have summarized the immune-based strategies for the development of COVID-19 vaccines and the different vaccine candidate platforms that are in clinical stages of evaluation, and up to the recently licensed mRNA-based COVID-19 vaccines of Pfizer-BioNtech and Moderna's. Lastly, we have briefly included the potentials of using the 'RPS-CTP vector system' for the development of a safe and effective oral mucosal COVID-19 vaccine as another vaccine platform.
The signaling pathways governing acetaminophen (APAP)-induced liver injury have been extensively studied. However, little is known about the ubiquitin-modifying enzymes needed for the regulation of ...APAP-induced liver injury. Here, we examined whether the Pellino3 protein, which has E3 ligase activity, is needed for APAP-induced liver injury and subsequently explored its molecular mechanism. Whole-body Peli3
knockout (KO) and adenovirus-mediated Peli3 knockdown (KD) mice showed reduced levels of centrilobular cell death, infiltration of immune cells, and biomarkers of liver injury, such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST), upon APAP treatment compared to wild-type (WT) mice. Peli3 deficiency in primary hepatocytes decreased mitochondrial and lysosomal damage and reduced the mitochondrial reactive oxygen species (ROS) levels. In addition, the levels of phosphorylation at serine 9 in the cytoplasm and mitochondrial translocation of GSK3β were decreased in primary hepatocytes obtained from Peli3
KO mice, and these reductions were accompanied by decreases in JNK phosphorylation and mitochondrial translocation. Pellino3 bound more strongly to GSK3β compared with JNK1 and JNK2 and induced the lysine 63 (K63)-mediated polyubiquitination of GSK3β. In rescue experiments, the ectopic expression of wild-type Pellino3 in Peli3
KO hepatocytes restored the mitochondrial translocation of GSK3β, but this restoration was not obtained with expression of a catalytically inactive mutant of Pellino3. These findings are the first to suggest a mechanistic link between Pellino3 and APAP-induced liver injury through the modulation of GSK3β polyubiquitination.
p62/sequestosome-1 is a scaffolding protein involved in diverse cellular processes such as autophagy, oxidative stress, cell survival and death. It has been identified to interact with atypical ...protein kinase Cs (aPKCs), linking these kinases to NF-κB activation by tumor necrosis factor α (TNFα). The diverse functions of p62 are regulated through post-translational modifications of several domains within p62. Among the enzymes that mediate these post-translational modifications, little is known about the deubiquitinating enzymes (DUBs) that remove ubiquitin chains from p62, compared to the E3 ligases involved in p62 ubiquitination. In this study, we first demonstrate a role of ubiquitin-specific protease USP20 in regulating p62 stability in TNFα-mediated NF-κB activation. USP20 specifically binds to p62 and acts as a positive regulator for NF-κB activation by TNFα through deubiquitinating lysine 48 (K48)-linked polyubiquitination, eventually contributing to cell survival. Furthermore, depletion of USP20 disrupts formation of the atypical PKCζ-RIPK1-p62 complex required for TNFα-mediated NF-κB activation and significantly increases the apoptosis induced by TNFα plus cycloheximide or TNFα plus TAK1 inhibitor. These findings strongly suggest that the USP20-p62 axis plays an essential role in NF-κB-mediated cell survival induced by the TNFα-atypical PKCζ signaling pathway.
We here demonstrate that SERTAD1 is an adaptor protein responsible for the regulation of lysine 63 (K63)-linked NLRP3 polyubiquitination by the Cullin1 E3 ubiquitin ligase upon inflammasome ...activation. SERTAD1 specifically binds to NLRP3 but not to other inflammasome sensors. This endogenous interaction increases after inflammasome activation, interfering with the interaction between NLRP3 and Cullin1. Interleukin (IL)-1β and IL-18 secretion, as well as the cleavage of gasdermin D, are decreased in SERTAD1 knockout bone-marrow-derived macrophages, together with reduced formation of the NLRP3 inflammasome complex. Additionally, SERTAD1-deficient mice show attenuated severity of monosodium-uric-acid-induced peritonitis and experimental autoimmune encephalomyelitis. Analysis of public datasets indicates that expression of SERTAD1 mRNA is significantly increased in the patients of autoimmune diseases. Thus, our findings uncover a function of SERTAD1 that specifically reduces Cullin1-mediated NLRP3 polyubiquitination via direct binding to NLRP3, eventually acting as a crucial factor to regulate the initiation of NLRP3-mediated inflammasome activation.
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•SERTAD1 binding to NLRP3 inhibits CUL1-mediated, K63-linked NLRP3 polyubiquitination•SERTAD1 knockout BMDMs show decreased IL-1β and IL-18 secretion and cleavage of gasdermin D•SERTAD1 depletion interferes with formation of the NLRP3 inflammasome complex•SERTAD1-deficient mice attenuate the severity of experimental autoimmune encephalomyelitis
Ha et al. show that SERTAD1 specifically reduces Cullin1-mediated NLRP3 polyubiquitination via direct binding to NLRP3, acting as a crucial factor to regulate the initiation of NLRP3-mediated inflammasome activation. They also reveal that SERTAD1 deficiency attenuates the symptoms of experimental autoimmune encephalomyelitis (EAE) and monosodium uric acid (MSU)-induced peritonitis.
Although bone morphogenetic protein 6 (BMP6) signaling pathway has been implicated in many types of cancer, its role of tumorigenesis seems to be controversial and its ubiquitin-modifying mechanisms ...have not been fully addressed. Our study was designed to investigate how BMP6 signaling pathway is regulated by ubiquitin-modifying systems and to address molecular and clinical significance in colorectal cancers.
Human deubiquitnase (DUB) siRNA library was used to screen the specific DUB, named PSMD14, involved in BMP6 signaling pathway. Immunoblot, immunoprecipitation and ubiquitination assays were used to analyze targets of the PSMD14. A role of PSMD14-mediated BMP6 signaling pathway for malignant cancer progression was investigated using in vitro and in vivo model of colorectal cancers as well as clinical samples of colorectal cancer patients.
The deubiquitinase PSMD14 acts as a positive regulator for the initiation of the BMP6 signaling pathway through deubiquitinating K48-linked ALK2 type I receptor ubiquitination mediated by Smurf1 E3 ligase, resulting in increased stability of the ALK2. This role of PSMD14 is independent of its intrinsic role in the 26S proteasome system. Furthermore, either PSMD14 or ALK2 depletion significantly decreases tumorigenesis of HCT116 colorectal cancer cells in a xenograft model as well as cancer stemness/chemoresistance, and expression of the PSMD14 and ALK2 gene are correlated with malignant progression and the survival of colorectal cancer patients.
These findings suggest that the PSMD14-ALK2 axis plays an essential role in initiation of the BMP6 signaling pathway and contributes to tumorigenesis and chemoresistance of colorectal cancers.
Although the ubiquitin-editing enzyme A20 is a key player in inflammation and autoimmunity, its role in cancer metastasis remains unknown. Here we show that A20 monoubiquitylates Snail1 at three ...lysine residues and thereby promotes metastasis of aggressive basal-like breast cancers. A20 is significantly upregulated in human basal-like breast cancers and its expression level is inversely correlated with metastasis-free patient survival. A20 facilitates TGF-β1-induced epithelial-mesenchymal transition (EMT) of breast cancer cells through multi-monoubiquitylation of Snail1. Monoubiquitylated Snail1 has reduced affinity for glycogen synthase kinase 3β (GSK3β), and is thus stabilized in the nucleus through decreased phosphorylation. Knockdown of A20 or overexpression of Snail1 with mutation of the monoubiquitylated lysine residues into arginine abolishes lung metastasis in mouse xenograft and orthotopic breast cancer models, indicating that A20 and monoubiquitylated Snail1 are required for metastasis. Our findings uncover an essential role of the A20-Snail1 axis in TGF-β1-induced EMT and metastasis of basal-like breast cancers.
Autophagy begins with the formation of autophagosomes, a process that depends on the activity of the serine/threonine kinase ULK1 (hATG1). Although earlier studies indicated that ULK1 activity is ...regulated by dynamic polyubiquitination, the deubiquitinase involved in the regulation of ULK1 remained unknown. In this study, we demonstrate that ubiquitin‐specific protease 20 (USP20) acts as a positive regulator of autophagy initiation through stabilizing ULK1. At basal state, USP20 binds to and stabilizes ULK1 by removing the ubiquitin moiety, thereby interfering with the lysosomal degradation of ULK1. The stabilization of basal ULK1 protein levels is required for the initiation of starvation‐induced autophagy, since the depletion of USP20 by RNA interference inhibits LC3 puncta formation, a marker of autophagic flux. At later stages of autophagy, USP20 dissociates from ULK1, resulting in enhanced ULK1 degradation and apoptosis. Taken together, our findings provide the first evidence that USP20 plays a crucial role in autophagy initiation by maintaining the basal expression level of ULK1.
Synopsis
The deubiquitinating enzyme USP20 acts as a positive regulator of autophagy initiation through the deubiquitination of ULK1. USP20 interferes with the lysosome‐dependent degradation of ULK1 and thereby maintains ULK1 stability at basal state.
USP20 deubiquitinates and stabilizes ULK1 at basal state.
USP20 depletion inhibits LC3 puncta formation after autophagy induction.
The USP20‐ULK1 complex dissociates after autophagy induction, resulting in enhanced ubiquitination of ULK1 and its degradation through a lysosome‐dependent pathway.
The deubiquitinating enzyme USP20 acts as a positive regulator of autophagy initiation through the deubiquitination of ULK1. USP20 interferes with the lysosome‐dependent degradation of ULK1 and thereby maintains ULK1 stability at basal state.
Mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into mature cells of various cell types. Although the differentiation process of MSCs requires lineage‐specific ...transcription factors, the exact molecular mechanism that determines MSCs differentiation is not clearly addressed. Here, we demonstrate a Smad4‐Taz axis as a new intrinsic regulator for adipo‐osteogenic differentiation of MSCs and show that this function of Smad4 is independent of the transforming growth factor‐β signal. Smad4 directly bound to the Taz protein and facilitated nuclear localization of Taz through its nuclear localization signal. Nuclear retention of Taz by direct binding to Smad4 increased expression of osteogenic genes through enhancing Taz‐runt‐related transcription factor 2 (Runx2) interactions in the C3H10T1/2 MSC cell line and preosteoblastic MC3T3‐E1 cells, whereas it suppressed expression of adipogenic genes through promoting Taz‐peroxisome proliferator‐activated receptor‐γ (PPARγ) interaction in C3H10T1/2 and preadipogenic 3T3‐L1 cells. A reciprocal role of the Smad4 in osteogenic and adipogenic differentiation was also observed in human adipose tissue‐derived stem cells (hASCs). Consequently, Smad4 depletion in C3H10T1/2 and hASCs reduced nuclear retention of Taz and thus caused the decreased interaction with Runx2 or PPARγ, resulting in delayed osteogenesis or enhanced adipogenesis of the MSC. Therefore, these findings provide insight into a novel function of Smad4 to regulate the balance of MSC lineage commitment through reciprocal targeting of the Taz protein in osteogenic and adipogenic differentiation pathways. Stem Cells 2019;37:368–381
Smad4 directly binds to Taz and induces the retention of Taz in the nucleus, resulting in enhancement of Taz interaction with runt‐related transcription factor 2 or peroxisome proliferator‐activated receptor‐γ. This increased interaction augments the expression of osteogenic genes or reduces the expression of adipogenic genes, respectively. Therefore, Smad4‐Taz axis reciprocally regulates osteogenic and adipogenic differentiation of mesenchymal stem cells.
NOD‐like receptor family protein 3 (NLRP3)‐mediated inflammasome activation promotes caspase‐1‐dependent production of interleukin‐1β (IL‐1β) and requires the adaptor protein ASC. Compared with the ...priming and activation mechanisms of the inflammasome signaling pathway, post‐translational ubiquitination/deubiquitination mechanisms controlling inflammasome activation have not been clearly addressed. We here demonstrate that the deubiquitinating enzyme USP50 binds to the ASC protein and subsequently regulates the inflammasome signaling pathway by deubiquitinating the lysine 63‐linked polyubiquitination of ASC. USP50 knockdown in human THP‐1 cells and mouse bone marrow‐derived macrophages shows a significant decrease in procaspase‐1 cleavage, resulting in a reduced secretion of IL‐1β and interleukin‐18 (IL‐18) upon treatment with NLRP3 stimuli and a reduction in ASC speck formation and oligomerization. Thus, we elucidate a novel regulatory mechanism of the inflammasome signaling pathway mediated by the USP50 deubiquitinating enzyme.
In this study, we analyzed the effect of forest damage caused by forest fires or shallow landslides on the rainfall thresholds needed to initiate bedload transport in mountain watersheds. Two bedload ...monitoring systems were used: a slot sampler and a hydrophone. These were installed in a forest fire-damaged site, a shallow landslide-damaged site, and a control site. A total of 199 effective rainfall-bedload data were collected from 2014 to 2016. Total rainfall amount (TR) and peak rainfall intensity (PRI) were found to be the most effective rainfall indices to predict bedload transport initiation. We also used linear functions to estimate percent threshold lines of the rainfall indices and used performance evaluations to select a representative threshold line for each site. As a result, the forest fire-damaged and shallow landslide-damaged sites had lower TR and PRI reference values than the control site, indicating that lower TR and PRI values can initiate bedload transport in damaged mountain forest areas. Although our study results may be limited by different characteristics between the study sites and insufficient data collection, it still indicates that forest damage caused by forest fires and shallow landslides affects bedload transport. Future studies are needed to further confirm these findings.
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