Ubiquitin Protease Research Articles

PCYT2 inhibits epithelial-to-mesenchymal transition in colorectal cancer by elevating YAP1 phosphorylation.

Metabolic reprogramming is a common feature in tumor progression and metastasis. Like proteins, lipids can transduce signals through lipid-protein interactions. During tumor initiation and metastasis, dysregulation of the Hippo pathway plays a critical role. Specifically, the inhibition of YAP1 phosphorylation leads to the relocation of YAP1 to the nucleus to activate transcription of genes involved in metastasis. Although recent studies reveal the involvement of phosphatidylethanolamine (PE) synthesis enzyme phosphoethanolamine cytidylyltransferase 2 (PCYT2) in tumor chemoresistance, the impact of PCYT2 on tumor metastasis remains elusive. Here, we showed that PCYT2 was significantly downregulated in metastatic colorectal cancer (CRC) and acted as a tumor metastasis suppressor. Mechanistically, PCYT2 increased the interaction between PEBP1 and YAP1-phosphatase PPP2R1A, thus disrupting PPP2R1A-YAP1 association. As a result, phosphorylated-YAP1 levels were increased, leading to YAP1 degradation through the ubiquitin protease pathway. YAP1 reduction in the nucleus repressed the transcription of ZEB1 and Snail2, eventually resulting in metastasis suppression. Our work provides insight into the role of PE synthesis in regulating metastasis and presents PCYT2 as a potential therapeutic target for CRC.

Physiological Parameters and Transcriptomic Levels Reveal the Response Mechanism of Maize to Deep Sowing and the Mechanism of Exogenous MeJA to Alleviate Deep Sowing Stress

Deep sowing, as a method to mitigate drought and preserve soil moisture and seedlings, can effectively mitigate the adverse effects of drought stress on seedling growth. The elongation of the hypocotyl plays an important role in the emergence of maize seeds from deep-sowing stress. This study was designed to explore the function of exogenous methyl jasmonate (MeJA) in the growth of the maize mesocotyl and to examine its regulatory network. The results showed that the addition of a 1.5 μ mol L−1 MeJA treatment significantly increased the mesocotyl length (MES), mesocotyl and coleoptile length (MESCOL), and seedling length (SDL) of maize seedlings. Transcriptome analysis showed that exogenous MeJA can alleviate maize deep-sowing stress, and the differentially expressed genes (DEGs) mainly include ornithine decarboxylase, terpene synthase 7, ethylene responsive transcription factor 11, and so on. In addition, candidate genes that may regulate the length of maize hypocotyls were screened by Weighted Gene Co-expression Network Analysis (WGCNA). These genes may be involved in the growth of maize hypocotyls through transcriptional regulation, histones, ubiquitin protease, protein binding, and chlorophyll biosynthesis and play an important role in maize deep-sowing tolerance. Our research findings may provide a theoretical basis for determining the tolerance of maize to deep-sowing stress and the mechanism of exogenous hormone regulation of deep-sowing stress.

Molecular glues that inhibit specific Zn2+-dependent DUB activity and inflammation.

Deubiquitylases (DUBs) play a pivotal role in cell signalling and are often regulated by homo- or hetero-interactions within protein complexes. The BRCC36 isopeptidase complex (BRISC) regulates inflammatory signalling by selectively cleaving K63-linked polyubiquitin chains on Type I interferon receptors (IFNAR1). BRCC36 is a Zn2+-dependent JAMM/MPN DUB, a challenging ubiquitin protease class for the design of selective inhibitors. We identified first-in-class DUB inhibitors that act as BRISC molecular glues (BLUEs). BLUEs inhibit DUB activity by stabilising a BRISC dimer consisting of 16 subunits. The BLUE-stabilised BRISC dimer is an autoinhibited conformation, whereby the active sites and interactions with the recruiting subunit SHMT2 are blocked. This unique mode of action leads to highly selective inhibitors for BRISC over related complexes with the same catalytic subunit, splice variants and other JAMM/MPN DUBs. Structure-guided inhibitor resistant mutants confirm BLUEs on-target activity in cells, and BLUE treatment results in reduced interferon-stimulated gene (ISG) expression in human peripheral blood mononuclear cells from Scleroderma patients, a disease linked with aberrant IFNAR1 activation. BLUEs represent a new class of molecules with potential utility in Type I interferon-mediated diseases and a template for designing selective inhibitors of large protein complexes by promoting protein-protein interactions instead of blocking them.

In the moonlight: non-catalytic functions of ubiquitin and ubiquitin-like proteases.

Proteases that cleave ubiquitin or ubiquitin-like proteins (UBLs) are critical players in maintaining the homeostasis of the organism. Concordantly, their dysregulation has been directly linked to various diseases, including cancer, neurodegeneration, developmental aberrations, cardiac disorders and inflammation. Given their potential as novel therapeutic targets, it is essential to fully understand their mechanisms of action. Traditionally, observed effects resulting from deficiencies in deubiquitinases (DUBs) and UBL proteases have often been attributed to the misregulation of substrate modification by ubiquitin or UBLs. Therefore, much research has focused on understanding the catalytic activities of these proteins. However, this view has overlooked the possibility that DUBs and UBL proteases might also have significant non-catalytic functions, which are more prevalent than previously believed and urgently require further investigation. Moreover, multiple examples have shown that either selective loss of only the protease activity or complete absence of these proteins can have different functional and physiological consequences. Furthermore, DUBs and UBL proteases have been shown to often contain domains or binding motifs that not only modulate their catalytic activity but can also mediate entirely different functions. This review aims to shed light on the non-catalytic, moonlighting functions of DUBs and UBL proteases, which extend beyond the hydrolysis of ubiquitin and UBL chains and are just beginning to emerge.

Effect of ubiquitin protease system on DNA damage response in prostate cancer (Review).

Genomic instability is an essential hallmark of cancer, and cellular DNA damage response (DDR) defects drive tumorigenesis by disrupting genomic stability. Several studies have identified abnormalities in DDR-associated genes, and a dysfunctional ubiquitin-proteasome system (UPS) is the most common molecular event in metastatic castration-resistant prostate cancer (PCa). For example, mutations in Speckle-type BTB/POZ protein-Ser119 result in DDR downstream target activation deficiency. Skp2 excessive upregulation inhibits homologous recombination repair and promotes cell growth and migration. Abnormally high expression of a deubiquitination enzyme, ubiquitin-specific protease 12, stabilizes E3 ligase MDM2, which further leads to p53 degradation, causing DDR interruption and genomic instability. In the present review, the basic pathways of DDR, UPS dysfunction, and its induced DDR alterations mediated by genomic instability, and especially the potential application of UPS and DDR alterations as biomarkers and therapeutic targets in PCa treatment, were described.

What Strengthens Protein-Protein Interactions: Analysis and Applications of Residue Correlation Networks

Identifying residues critical to protein–protein binding and efficient design of stable and specific protein binders are challenging tasks. Extending beyond the direct contacts in a protein–protein binding interface, our study employs computational modeling to reveal the essential network of residue interactions and dihedral angle correlations critical in protein–protein recognition. We hypothesized that mutating residues exhibiting highly correlated dynamic motion within the interaction network could efficiently optimize protein–protein interactions to create tight and selective protein binders. We tested this hypothesis using the ubiquitin (Ub) and MERS coronaviral papain-like protease (PLpro) complex, since Ub is a central player in multiple cellular functions and PLpro is an antiviral drug target. Our designed ubiquitin variant (UbV) hosting three mutated residues displayed a ∼3,500-fold increase in functional inhibition relative to wild-type Ub. Further optimization of two C-terminal residues within the Ub network resulted in a KD of 1.5 nM and IC50 of 9.7 nM for the five-point Ub mutant, eliciting 27,500-fold and 5,500-fold enhancements in affinity and potency, respectively, as well as improved selectivity, without destabilizing the UbV structure. Our study highlights residue correlation and interaction networks in protein–protein interactions, and introduces an effective approach to design high-affinity protein binders for cell biology research and future therapeutics.

Integrative analysis of genome and transcriptome reveal the genetic basis of high temperature tolerance in pleurotus giganteus (Berk. Karun & Hyde)

BackgroundPleurotus giganteus is a commonly cultivated mushroom with notable high temperature resistance, making it significant for the growth of the edible fungi industry in the tropics. Despite its practical importance,, the genetic mechanisms underlying its ability to withstand high temperature tolerance remain elusive.ResultsIn this study, we performed high-quality genome sequencing of a monokaryon isolated from a thermotolerant strain of P. giganteus. The genome size was found to be 40.11 Mb, comprising 17 contigs and 13,054 protein-coding genes. Notably, some genes related to abiotic stress were identified in genome, such as genes regulating heat shock protein, protein kinase activity and signal transduction. These findings provide valuable insights into the genetic basis of P. giganteus’ high temperature resistance. Furthermore, the phylogenetic tree showed that P. giganteus was more closely related to P. citrinopileatus than other Pleurotus species. The divergence time between Pleurotus and Lentinus was estimated as 153.9 Mya, and they have a divergence time with Panus at 168.3 Mya, which proved the taxonomic status of P. giganteus at the genome level. Additionally, a comparative transcriptome analysis was conducted between mycelia treated with 40 °C heat shock for 18 h (HS) and an untreated control group (CK). Among the 2,614 differentially expressed genes (DEGs), 1,303 genes were up-regulated and 1,311 were down-regulated in the HS group. The enrichment analysis showed that several genes related to abiotic stress, including heat shock protein, DnaJ protein homologue, ubiquitin protease, transcription factors, DNA mismatch repair proteins, and zinc finger proteins, were significantly up-regulated in the HS group. These genes may play important roles in the high temperature adaptation of P. giganteus. Six DEGs were selected according to fourfold expression changes and were validated by qRT-PCR, laying a good foundation for further gene function analysis.ConclusionOur study successfully reported a high-quality genome of P. giganteus and identified genes associated with high-temperature tolerance through an integrative analysis of the genome and transcriptome. This study lays a crucial foundation for understanding the high-temperature tolerance mechanism of P. giganteus, providing valuable insights for genetic modification of P. giganteus strains and the development of high-temperature strains for the edible fungus industry, particularly in tropical regions.

Tumor-promoting action of ubiquitin protease 43 in gastric cancer progression through deubiquitination and stabilization of stress-inducible phosphoprotein 1

Gastric cancer (GC) is the 5th most common cancer over the world. Ubiquitin protease 43 (UBP43) is a multifunctional protein with deubiquitinase activities. Abnormal expression of UBP43 has been reported in numerous types of malignancies. Bioinformatic analysis was performed to identify the differentially expressed genes (Fold change ≥2 or ≤ −2 and p < 0.01) in GC from the datasets downloaded from Gene Expression Omnibus and Gene Expression Profiling Interactive Analysis databases, which showed that UBP43 and stress-inducible phosphoprotein 1 (STIP1) were up-regulated in both datasets. Online databases displayed the binding of UBP43 to STIP1 and the positive correlation between the two proteins. This study aims to explore: the role of UBP43 in cell proliferation and apoptosis in GC; the relationship between UBP43 and STIP1; and whether UBP43 exerts its function via STIP1 in GC. Knockdown/overexpression stable GC cell lines were generated by transducing lentivirus carrying coding sequence/short hairpin RNA of UBP43 and puromycin selection. GC patients with higher expressions of UBP43 had poor prognosis. Loss-/gain-of-function experiments revealed that pro-proliferative and anti-apoptotic abilities of UBP43 in GC cells and xenografts. UBP43 could interact with STIP1, inhibit its ubiquitination, and promote its protein stability, thereby enhancing STIP1 expression. Moreover, STIP1 knockdown reversed the pro-proliferative ability of UBP43 in GC cells. Our study uncovers that the pro-proliferative role of UBP43 in GC development is STIP1-dependent and indicates that UBP43 may act as a potent therapeutic target in GC treatment.

BnaUBP15s positively regulates seed size and seed weight in Brassica napus

Brassica napus (B. napus) is a globally significant oilseed crop, making a substantial contribution to both human oil and livestock feed production. Enhancing seed weight is crucial for improving rapeseed yield; however, only a limited number of seed weight-related genes have been functionally validated in B. napus thus far. UBIQUITIN-SPECIFIC PROTEASE 15 (UBP15) belongs to the ubiquitin protease pathway and plays a maternal role in prolonging seed development in Arabidopsis. The potential utilization of UBP15 for enhancing seed yield in B. napus has remained unexplored until now. In this study, we identified the orthologs of UBP15 in B. napus and investigated its functionality using the CRISPR-Cas9 system. We generated mutant plants with multiple editing types targeting Bnaubp15s and successfully isolated T-DNA-free homozygous mutant lines that exhibited edits across four homologs of BnaUBP15 in T2 generation plants. Our preliminary data demonstrated that mutation of BnaUBP15s significantly reduced seed size, seed weight, and plant height while noticeably increasing the number of primary branches. These findings not only provide crucial evidence for further elucidating the molecular mechanism underlying the regulation of seed weight and size by BnaUBP15s but also offer promising novel germplasm for enhancing plant architecture.

NpPP2-B10, an F-Box-Nictaba Gene, Promotes Plant Growth and Resistance to Black Shank Disease Incited by Phytophthora nicotianae in Nicotiana tabacum.

Black shank, a devastating disease affecting tobacco production worldwide, is caused by Phytophthora nicotianae. However, few genes related to Phytophthora resistance have been reported in tobacco. Here, we identified NpPP2-B10, a gene strongly induced by P. nicotianae race 0, with a conserved F-box motif and Nictaba (tobacco lectin) domain, in the highly resistant tobacco species Nicotiana plumbaginifolia. NpPP2-B10 is a typical F-box-Nictaba gene. When it was transferred into the black shank-susceptible tobacco cultivar 'Honghua Dajinyuan', it was found to promote resistance to black shank disease. NpPP2-B10 was induced by salicylic acid, and some resistance-related genes (NtPR1, NtPR2, NtCHN50, and NtPAL) and resistance-related enzymes (catalase and peroxidase) were significantly upregulated in the overexpression lines after infection with P. nicotianae. Furthermore, we showed that NpPP2-B10 actively regulated the tobacco seed germination rate, growth rate, and plant height. The erythrocyte coagulation test of purified NpPP2-B10 protein showed that NpPP2-B10 had plant lectin activity, and the lectin content in the overexpression lines was significantly higher than that in the WT, which could lead to accelerated growth and improved resistance of tobacco. SKP1 is an adaptor protein of the E3 ubiquitin ligase SKP1, Cullin, F-box (SCF) complex. We demonstrated that NpPP2-B10 could interact with the NpSKP1-1A gene in vivo and in vitro through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC), indicating that NpPP2-B10 likely participates in the plant immune response by mediating the ubiquitin protease pathway. In conclusion, our study provides some important insights concerning NpPP2-B10-mediated regulation of tobacco growth and resistance.

Research progress of E3 ubiquitin ligase regulating biological behavior of human placental trophoblast cells.

E3 ubiquitin ligases are important components of the ubiquitin protease system. This family includes many proteins, which can catalyze the ubiquitination of a variety of protein substrates and promote the degradation of them by the proteasome system. Recent studies have shown that E3 ubiquitin ligase plays a key role in the process of fetal development and placental formation. It affects the biological behavior of placental trophoblast cells, leading to a series of pregnancy complications that threaten mothers and babies greatly. This review focuses on the regulation, target and mechanism of E3 ubiquitin ligase on the biological behavior of human placental trophoblast cells.

Bioinformatics findings reveal the pharmacological properties of ferulic acid treating traumatic brain injury via targeting of ferroptosis

ABSTRACT Ferroptosis refers to a lytic cell death avenue that may be related to the development of neuropathological disorders. Traumatic brain injury (TBI) is the brain impairments and ferroptosis is found with the pathological role in TBI development. Our previous findings showed that ferulic acid exerts pharmacological benefited against TBI. However, the therapeutic efficacy and mechanism targeting of ferroptosis in ferulic acid against TBI is still unclear. In current report, an integrated approach by using network pharmacology and molecular docking analyses was subjected to identify the ferulic acid-anti-TBI mechanisms and targets associated with ferroptosis. The network pharmacology analysis had screened 184 ferulic acid-related targets, 1834 TBI-associated targets and 616 ferroptosis-linked targets, characterized with 14 overlapping genes among ferulic acid, TBI, and ferroptosis. All core targets in ferulic acid treating TBI via regulation of ferroptosis were identified through parametric determination, including PTGS2, TLR4, RELA, GSK3B, NFE2L2, EGFR, and MIF. Following with enrichment analysis, anti-TBI functions of ferulic acid against TBI targeting ferroptosis were revealed in multiple biological processes, including regulation of polymerase activities, transcription factor functions, ubiquitin protease binding capabilities. Pharmacological mechanisms were detailed in signaling pathways mainly involved in neuroprotection, microenvironmental restoration and neural regeneration were the key functional characteristics. Further in silico validation exhibited that PTGS2 was a potential pharmacological target associated with ferroptosis in ferulic acid against TBI owing to the potent binding energy. Collectively, current bioinformatics data provide a new preclinical insight of the pharmacological function and mechanism targeting of ferroptosis in ferulic acid treating TBI. Compared to other correlative researches, this study may effectively exhibit the preclinical perspective in new drug research and development on ferulic acid against TBI through revealing multiple targets and pathways.

The deubiquitinase USP8 regulates ovarian cancer cell response to cisplatin by suppressing apoptosis.

The identification of therapeutic approaches to improve response to platinum-based therapies is an urgent need for ovarian carcinoma. Deubiquitinases are a large family of ubiquitin proteases implicated in a variety of cellular functions and may contribute to tumor aggressive features through regulation of processes such as proliferation and cell death. Among the subfamily of ubiquitin-specific peptidases, USP8 appears to be involved in modulation of cancer cell survival by still poorly understood mechanisms. Thus, we used ovarian carcinoma cells of different histotypes, including cisplatin-resistant variants with increased survival features to evaluate the efficacy of molecular targeting of USP8 as a strategy to overcome drug resistance/modulate cisplatin response. We performed biochemical analysis of USP8 activity in pairs of cisplatin-sensitive and -resistant cells and found increased USP8 activity in resistant cells. Silencing of USP8 resulted in decreased activation of receptor tyrosine kinases and increased sensitivity to cisplatin in IGROV-1/Pt1 resistant cells as shown by colony forming assay. Increased cisplatin sensitivity was associated with enhanced cisplatin-induced caspase 3/7 activation and apoptosis, a phenotype also observed in cisplatin sensitive cells. Increased apoptosis was linked to FLIPL decrease and cisplatin induction of caspase 3 in IGROV-1/Pt1 cells, cisplatin-induced claspin and survivin down-regulation in IGROV-1 cells, thereby showing a decrease of anti-apoptotic proteins. Immunohistochemical staining on 65 clinical specimens from advanced stage ovarian carcinoma indicated that 40% of tumors were USP8 positive suggesting that USP8 is an independent prognostic factor for adverse outcome when considering progression free survival as a clinical end-point. Taken together, our results support that USP8 may be of diagnostic value and may provide a therapeutic target to improve the efficacy of platinum-based therapy in ovarian carcinoma.

Hypoglycemic drug liraglutide alleviates low muscle mass by inhibiting the expression of MuRF1 and MAFbx in diabetic muscle atrophy.

Low muscle mass, that is, muscular atrophy, is an independent risk factor for type 2 diabetes mellitus (T2DM). Few studies investigated whether hypoglycemic drugs can alleviate low muscle mass and related mechanisms. This study recruited 51 type 2 diabetes mellitus (T2DM) patients, who were divided into two groups based on skeletal muscle index (SMI) evaluated by Dual-energy X-ray absorptiometry (DXA): the experiment group (n = 25, SMI < 7 kg/m 2 ) and the control group (n = 26, SMI≥7 kg/m 2 ). GLP-1 levels were measured by ELISA. In vitro, 10 KK-A y mice (11- to 12-week-old) were assigned into two groups: liraglutide group (n = 5) and saline group (n = 5). Real-time PCR and Western blot were used to determine the expression levels of muscle specific ubiquitin protease E3, MuRF1, and MAFbx. T2DM patients with a higher SMI had significantly higher GLP-1 levels (t = 3.77, p < 0.001). SMI were positively associated with GLP-1 levels (β = 0.435, p = 0.001) and inversely associated with age (β = 0.299, p = 0.015). The incidence of low muscle mass at below the second quartiles was 10.55 times that of above the second quartiles (odds ratio = 10.556, p < 0.001). Liraglutide-treatment mice showed significant decrease in food intake, final body weight, fasting blood glucose, and significant increase in skeletal muscle mass, which coincided with the significant decrease in the expression levels of ubiquitin protease E3 MuRF1 and MAFbx. In vitro studies showed that liraglutide promoted myogenic differentiation and attenuated dexamethasone (DEX)-induced myotube atrophy. Ectopic expression of MuRF1 and MAFbx antagonized the beneficial effects of liraglutide on DEX-induced myotube atrophy. T2DM patients have muscular atrophy, and liraglutide alleviates muscular atrophy at least in part by inhibiting the expression of MuRF1 and MAFbx.

The OH system: A panorama view of the PPV-host interaction.

Poxviruses are a family of specialized cytoplasm-parasitic DNA viruses that replicate and assembly in virus factory. In Parapoxvirus (PPV) genus, with the orf virus (ORFV) as a representative species of this genus, their behaviors are significantly different from that of Orthopoxvirus, and the plots of viral practical solutions for evading host immunity are intricate and fascinating, particularly to anti-host and host's antiviral mechanisms. In order to protect the virus factory from immune elimination caused by infection, PPVs attempt to interfere with multiple stress levels of host, mainly by modulating innate immunity response (IIR) and adaptive immunity response (AIR). Given that temporarily constructed by virus infection, ORFV-HOST (OH) system accompanied by viral strategies is carefully managed in the virus factory, thus directing many life-critical events once undergoing the IIR and AIR. Evolutionarily, to reduce the risk of system destruction, ORFV have evolved into a mild-looking mode to avoid overstimulation. Moreover, the current version of development also focus on recognizing and hijacking more than eight antiviral security mechanisms of host cells, such as the 2',5'-oligoadenylate synthetase (OAS)/RNase L and PKR systems, the ubiquitin protease system (UPS), and so on. In summary, this review assessed inescapable pathways as mentioned above, through which viruses compete with their hosts strategically. The OH system provides a panoramic view and a powerful platform for us to study the PPV-Host interaction, as well as the corresponding implications on a great application potential in anti-virus design.

Oxygen sensors mediated HIF-1α accumulation and translocation: A pivotal mechanism of fine particles-exacerbated myocardial hypoxia injury

Epidemiological studies have demonstrated a strong association of ambient fine particulate matter (PM2.5) exposure with the increasing mortality by ischemic heart disease (IHD), but the involved mechanisms remain poorly understood. Herein, we found that the chronic exposure of real ambient PM2.5 led to the upregulation of hypoxia-inducible factor-1 alpha (HIF-1α) protein in the myocardium of mice, accompanied by obvious myocardial injury and hypertrophy. Further data from the hypoxia-ischemia cellular model indicated that PM2.5-induced HIF-1α accumulation was responsible for the promotion of myocardial hypoxia injury. Moreover, the declined ATP level due to the HIF-1α-mediated energy metabolism remodeling from β-oxidation to glycolysis had a critical role in the PM2.5-increased myocardial hypoxia injury. The in-depth analysis delineated that PM2.5 exposure decreased the binding of prolyl hydroxylase domain 2 (PHD2) and HIF-1α and subsequent ubiquitin protease levels, thereby leading to the accumulation of HIF-1α. Meanwhile, factor-inhibiting HIF1 (FIH1) expression was down-regulated by PM2.5, resulting in the enhanced translocation of HIF-1α to the nucleus. Overall, our study provides valuable insight into the regulatory role of oxygen sensor-mediated HIF-1α stabilization and translocation in PM-exacerbated myocardial hypoxia injury, we suggest this adds significantly to understanding the mechanisms of haze particles-caused burden of cardiovascular disease.

TRAF proteins as key regulators of plant development and stress responses.

Tumor necrosis factor receptor-associated factor (TRAF) proteins are conserved in higher eukaryotes and play key roles in transducing cellular signals across different organelles. They are characterized by their C-terminal region (TRAF-C domain) containing seven to eight anti-parallel β-sheets, also known as the meprin and TRAF-C homology (MATH) domain. Over the past few decades, significant progress has been made toward understanding the diverse roles of TRAF proteins in mammals and plants. Compared to other eukaryotic species, the Arabidopsis thaliana and rice (Oryza sativa) genomes encode many more TRAF/MATH domain-containing proteins; these plant proteins cluster into five classes: TRAF/MATH-only, MATH-BPM, MATH-UBP (ubiquitin protease), Seven in absentia (SINA), and MATH-Filament and MATH-PEARLI-4 proteins, suggesting parallel evolution of TRAF proteins in plants. Increasing evidence now indicates that plant TRAF proteins form central signaling networks essential for multiple biological processes, such as vegetative and reproductive development, autophagosome formation, plant immunity, symbiosis, phytohormone signaling, and abiotic stress responses. Here, we summarize recent advances and highlight future prospects for understanding on the molecular mechanisms by which TRAF proteins act in plant development and stress responses.

Downregulating expression of OPTN elevates neuroinflammation via AIM2 inflammasome- and RIPK1-activating mechanisms in APP/PS1 transgenic mice

BackgroundNeuroinflammation is thought to be a cause of Alzheimer’s disease (AD), which is partly caused by inadequate mitophagy. As a receptor of mitophagy, we aimed to reveal the regulatory roles of optineurin (OPTN) on neuroinflammation in the pathogenesis of AD.MethodsBV2 cells and APP/PS1 transgenic (Tg) mice were used as in vitro and in vivo experimental models to determine the regulatory roles of OPTN in neuroinflammation of AD. Sophisticated molecular technologies including quantitative (q) RT-PCR, western blot, enzyme linked immunosorbent assay (ELISA), co-immunoprecipitation (Co-IP) and immunofluorescence (IF) were employed to reveal the inherent mechanisms.ResultsAs a consequence, key roles of OPTN in regulating neuroinflammation were identified by depressing the activity of absent in melanoma 2 (AIM2) inflammasomes and receptor interacting serine/threonine kinase 1 (RIPK1)-mediated NF-κB inflammatory mechanisms. In detail, we found that expression of OPTN was downregulated, which resulted in activation of AIM2 inflammasomes due to a deficiency in mitophagy in APP/PS1 Tg mice. By ectopic expression, OPTN blocks the effects of Aβ oligomer (Aβo) on activating AIM2 inflammasomes by inhibiting mRNA expression of AIM2 and apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), leading to a reduction in the active form of caspase-1 and interleukin (IL)-1β in microglial cells. Moreover, RIPK1 was also found to be negatively regulated by OPTN via ubiquitin protease hydrolysis, resulting in the synthesis of IL-1β by activating the transcriptional activity of NF-κB in BV2 cells. As an E3 ligase, the UBAN domain of OPTN binds to the death domain (DD) of RIPK1 to facilitate its ubiquitination. Based on these observations, ectopically expressed OPTN in APP/PS1 Tg mice deactivated microglial cells and astrocytes via the AIM2 inflammasome and RIPK-dependent NF-κB pathways, leading to reduce neuroinflammation.ConclusionsThese results suggest that OPTN can alleviate neuroinflammation through AIM2 and RIPK1 pathways, suggesting that OPTN deficiency may be a potential factor leading to the occurrence of AD.

XRCC1 protects transcription from toxic PARP1 activity during DNA base excision repair

Genetic defects in the repair of DNA single-strand breaks (SSBs) can result in neurological disease triggered by toxic activity of the single-strand-break sensor protein PARP1. However, the mechanism(s) by which this toxic PARP1 activity triggers cellular dysfunction are unclear. Here we show that human cells lacking XRCC1 fail to rapidly recover transcription following DNA base damage, a phenotype also observed in patient-derived fibroblasts with XRCC1 mutations and Xrcc1−/− mouse neurons. This defect is caused by excessive/aberrant PARP1 activity during DNA base excision repair, resulting from the loss of PARP1 regulation by XRCC1. We show that aberrant PARP1 activity suppresses transcriptional recovery during base excision repair by promoting excessive recruitment and activity of the ubiquitin protease USP3, which as a result reduces the level of monoubiquitinated histones important for normal transcriptional regulation. Importantly, inhibition and/or deletion of PARP1 or USP3 restores transcriptional recovery in XRCC1−/− cells, highlighting PARP1 and USP3 as possible therapeutic targets in neurological disease.

Expression and clinical significance of UBE2V1 in cervical cancer

The majority of cervical cancer (CC) patients are caused by the high-risk human papillomavirus (HPV) infection Although they are preventable and controllable, the mortality rate is still high. It is essential to identify the biomarkers for early screening and diagnosis of CC to improve the prognosis of patients with CC. The conjugating enzyme 2 (E2) family members are the key components of ubiquitin protease system. However, the role of E2 family in CC remains unclear. We aimed to investigate the role of UBE2V1, a ubiquitin binding E2 enzyme variant protein (ube2v) without conserved cysteine residues required for E2s catalytic activity in CC. In this study, we first studied the expression of UBE2V1 in CC by real time quantitative PCR (RT-qPCR), and then, the clinical information of 191 CC patients in TCGA database was retrieved to explore the relationship between the expression of UBE2V1 and the occurrence and development of CC by examining the translational profile and methylation, the high expression of UBE2V1 was well correlated to the poor prognosis of patients, indicating that UBE2V1 is an independent risk factor for the prognosis of CC patients. The expression of UBE2V1 was also correlated with clinical stages, tumor grades and TNM stages of CC. In addition, the expression of UBE2V1 was slightly negatively correlated with the methylation at the multiple methylation sites. our study revealed the relationship between UBE2V1 and the occurrence and development of CC from the level of transcriptional profile and DNA methylation. UBE2V1 is a novel candidate biomarker for the diagnosis, screening and prognosis of CC.