UCHL3 induces radiation resistance and acquisition of mesenchymal phenotypes by deubiquitinating POLD4 in glioma stem cells.

BACKGROUND: The high degree of intratumoral genomic heterogeneity is a major obstacle for glioblastoma (GBM) tumors, one of the most lethal human malignancies, and is thought to influence conventional therapeutic outcomes negatively. The proneural-to-mesenchymal transition (PMT) of glioma stem cells (GSCs) confers resistance to radiation therapy in glioblastoma patients. POLD4 is associated with cancer progression, while the mechanisms underlying PMT and tumor radiation resistance have remained elusive. METHOD: Expression and prognosis of the POLD family were analyzed in TCGA, the Chinese Glioma Genome Atlas (CGGA) and GEO datasets. Tumorsphere formation and in vitro limiting dilution assay were performed to investigate the effect of UCHL3-POLD4 on GSC self-renewal. Apoptosis, TUNEL, cell cycle phase distribution, modification of the Single Cell Gel Electrophoresis (Comet), γ-H2AX immunofluorescence, and colony formation assays were conducted to evaluate the influence of UCHL3-POLD4 on GSC in ionizing radiation. Coimmunoprecipitation and GST pull-down assays were performed to identify POLD4 protein interactors. In vivo, intracranial xenograft mouse models were used to investigate the molecular effect of UCHL3, POLD4 or TCID on GCS. RESULT: We determined that POLD4 was considerably upregulated in MES-GSCs and was associated with a meagre prognosis. Ubiquitin carboxyl terminal hydrolase L3 (UCHL3), a DUB enzyme in the UCH protease family, is a bona fide deubiquitinase of POLD4 in GSCs. UCHL3 interacted with, depolyubiquitinated, and stabilized POLD4. Both in vitro and in vivo assays indicated that targeted depletion of the UCHL3-POLD4 axis reduced GSC self-renewal and tumorigenic capacity and resistance to IR treatment by impairing homologous recombination (HR) and nonhomologous end joining (NHEJ). Additionally, we proved that the UCHL3 inhibitor TCID induced POLD4 degradation and can significantly enhance the therapeutic effect of IR in a gsc-derived in situ xenograft model. CONCLUSION: These findings reveal a new signaling axis for GSC PMT regulation and highlight UCHL3-POLD4 as a potential therapeutic target in GBM. TCID, targeted for reducing the deubiquitinase activity of UCHL3, exhibited significant synergy against MES GSCs in combination with radiation.

Comprehensive analysis of the relationship between ubiquitin-specific protease 21 (USP21) and prognosis, tumor microenvironment infiltration, and therapy response in colorectal cancer.

BACKGROUND: Ubiquitin-specific proteases family is crucial to host immunity against pathogens. However, the correlations between USP21 and immunosurveillance and immunotherapy for colorectal cancer (CRC) have not been reported. METHODS: The differential expression of USP21 between CRC tissues and normal tissues was analyzed using multiple public databases. Validation was carried out in clinical samples through qRT-PCR and IHC. The correlation between USP21 and the prognosis, as well as clinical pathological characteristics of CRC patients, was investigated. Moreover, cell models were established to assess the influence of USP21 on CRC growth and progression, employing CCK-8 assays, colony formation assays, and wound-healing assays. Subsequently, gene set variation analysis (GSVA) was used to explore the potential biological functions of USP21 in CRC. The study also examined the impact of USP21 on cytokine levels and immune cell infiltration in the tumor microenvironment (TME). Finally, the effect of USP21 on the response to immunotherapy and chemotherapy in CRC was analyzed. RESULTS: The expression of USP21 was significantly upregulated in CRC. High USP21 is correlated with poor prognosis in CRC patients and facilitates the proliferation and migration capacities of CRC cells. GSVA indicated an association between low USP21 and immune activation. Moreover, low USP21 was linked to an immune-activated TME, characterized by high immune cell infiltration. Importantly, CRC with low USP21 exhibited higher tumor mutational burden, high PD-L1 expression, and better responsiveness to immunotherapy and chemotherapeutic drugs. CONCLUSION: This study revealed the role of USP21 in TME, response to therapy, and clinical prognosis in CRC, which provided novel insights for the therapeutic application in CRC.

USP22 as a key regulator of glycolysis pathway in osteosarcoma: insights from bioinformatics and experimental approaches.

Background: Osteosarcoma is the most common primary malignant bone tumor, but its pathogenesis remains unclear. Ubiquitin-specific processing peptidase 22 (USP22) is reported to be highly expressed and associated with tumor malignancy and prognosis in cancers. However, the role and mechanism of USP22 in osteosarcoma is not fully understood. This study aims to investigate the function and potential mechanism of USP22 in osteosarcoma using bioinformatics analysis combined with experimental validation. Methods: We first integrated transcriptomic datasets and clinical information of osteosarcoma from GEO and TCGA databases to assess the expression and prognostic value of USP22 in osteosarcoma. Then, differential expression analysis and weighted gene co-expression network analysis (WGCNA) were conducted to identify USP22-related co-expressed genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore the biological functions and signaling pathways of USP22 co-expressed genes. To validate the accuracy of bioinformatics analyses, we downregulated USP22 expression in osteosarcoma cell line Sao-2 using siRNA and assessed its effect on cell proliferation, migration, invasion, apoptosis, and regulation of key signaling pathways. Results: We found that USP22 was highly expressed in osteosarcoma tissues and correlated with poor prognosis in osteosarcoma patients. USP22 also showed potential as a diagnostic marker for osteosarcoma. In addition, 344 USP22-related co-expressed genes were identified, mainly involved in signaling pathways such as glycolysis, oxidative phosphorylation, spliceosome, thermogenesis, and cell cycle. The in vitro experiments confirmed the accuracy and reliability of bioinformatics analyses. We found that downregulation of USP22 could inhibit Sao-2 cell proliferation, migration, invasion, and induce apoptosis. Furthermore, downregulation of USP22 significantly reduced aerobic glycolysis levels in Sao-2 cells and inhibited the expression of key enzymes and transporters in aerobic glycolysis pathways such as HK2, PKM2, and GLUT1. Conclusions: USP22 plays a critical role in the occurrence, development, and prognosis of osteosarcoma. USP22 could influence Sao-2 cell proliferation, apoptosis, migration, and invasion by regulating the glycolysis pathway, thereby promoting osteosarcoma progression. Therefore, USP22 may be a potential therapeutic target for the treatment of osteosarcoma.

Metrnl inhibits choroidal neovascularization by attenuating the choroidal inflammation via inactivating the UCHL-1/NF-κB signaling pathway.

Objective: Choroidal neovascularization (CNV) represents the predominant form of advanced wet Age-related Macular Degeneration (wAMD). Macrophages play a pivotal role in the pathological progression of CNV. Meteorin-like (Metrnl), a novel cytokine known for its anti-inflammatory properties in macrophages, is the focus of our investigation into its mechanism of action and its potential to impede CNV progression. Methods: Cell viability was evaluated through CCK-8 and EdU assays following Metrnl treatment. Expression levels of inflammatory cytokines and proteins were assessed using quantitative reverse-transcription polymerase chain reaction(qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and western blot techniques. Protein-protein interactions were identified through protein mass spectrometry and co-immunoprecipitation (Co-IP). Additionally, in vivo and in vitro neovascularization models were employed to evaluate angiogenesis. Results: Our results revealed downregulated Metrnl levels in the choroid-sclera complex of CNV mice, the aqueous humor of wAMD patients, and activated macrophages. Metrnl overexpression demonstrated a reduction in pro-inflammatory cytokine production, influenced endothelial cell function, and suppressed angiogenesis in choroid explants and CNV models. Through protein mass spectrometry and Co-IP, we confirmed Metrnl binds to UCHL-1 to modulate the NF-κB signaling pathway. This interaction inhibited the transcription and expression of pro-inflammatory cytokines, ultimately suppressing angiogenesis. Conclusion: In summary, our findings indicate that Metrnl down-regulates macrophage pro-inflammatory cytokine secretion via the UCHL-1/NF-κB signaling pathway. This mechanism alleviates the inflammatory microenvironment and effectively inhibits choroidal neovascularization.

Ruthenium red alleviates post-resuscitation myocardial dysfunction by upregulating mitophagy through inhibition of USP33 in a cardiac arrest rat model.

Cardiac arrest (CA) remains a leading cause of death, with suboptimal survival rates despite efforts involving cardiopulmonary resuscitation and advanced life-support technology. Post-resuscitation myocardial dysfunction (PRMD) is an important determinant of patient outcomes. Myocardial ischemia/reperfusion injury underlies this dysfunction. Previous reports have shown that ruthenium red (RR) has a protective effect against cardiac ischemia-reperfusion injury; however, its precise mechanism of action in PRMD remains unclear. This study investigated the effects of RR on PRMD and analyzed its underlying mechanisms. Ventricular fibrillation was induced in rats, which were then subjected to cardiopulmonary resuscitation to establish an experimental CA model. At the onset of return of spontaneous circulation, RR (2.5 mg/kg) was administered intraperitoneally. Our study showed that RR improved myocardial function and reduced the production of oxidative stress markers such as malondialdehyde (MDA), glutathione peroxidase (GSSG), and reactive oxygen species (ROS) production. RR also helped maintain mitochondrial structure and increased ATP and GTP levels. Additionally, RR effectively attenuated myocardial apoptosis. Furthermore, we observed downregulation of proteins closely related to mitophagy, including ubiquitin-specific protease 33 (USP33) and P62, whereas LC3B (microtubule-associated protein light chain 3B) was upregulated. The upregulation of mitophagy may play a critical role in reducing myocardial injury. These results demonstrate that RR may attenuate PRMD by promoting mitophagy through the inhibition of USP33. These effects are likely mediated through diverse mechanisms, including antioxidant activity, apoptosis suppression, and preservation of mitochondrial integrity and energy metabolism. Consequently, RR has emerged as a promising therapeutic approach for addressing post-resuscitation myocardial dysfunction.

BAP1 is required prenatally for differentiation and maintenance of postnatal murine enteric nervous system.

Epigenetic regulatory mechanisms are underappreciated, yet are critical for enteric nervous system (ENS) development and maintenance. We discovered that fetal loss of the epigenetic regulator Bap1 in the ENS lineage caused severe postnatal bowel dysfunction and early death in Tyrosinase-Cre Bap1fl/fl mice. Bap1-depleted ENS appeared normal in neonates; however, by P15, Bap1-deficient enteric neurons were largely absent from the small and large intestine of Tyrosinase-Cre Bap1fl/fl mice. Bowel motility became markedly abnormal with disproportionate loss of cholinergic neurons. Single-cell RNA sequencing at P5 showed that fetal Bap1 loss in Tyrosinase-Cre Bap1fl/fl mice markedly altered the composition and relative proportions of enteric neuron subtypes. In contrast, postnatal deletion of Bap1 did not cause enteric neuron loss or impaired bowel motility. These findings suggest that BAP1 is critical for postnatal enteric neuron differentiation and for early enteric neuron survival, a finding that may be relevant to the recently described human BAP1-associated neurodevelopmental disorder.

Stress Granule Core Protein-Derived Peptides Inhibit Assembly of Stress Granules and Improve Sorafenib Sensitivity in Cancer Cells.

Upon a variety of environmental stresses, eukaryotic cells usually recruit translational stalled mRNAs and RNA-binding proteins to form cytoplasmic condensates known as stress granules (SGs), which minimize stress-induced damage and promote stress adaptation and cell survival. SGs are hijacked by cancer cells to promote cell survival and are consequently involved in the development of anticancer drug resistance. However, the design and application of chemical compounds targeting SGs to improve anticancer drug efficacy have rarely been studied. Here, we developed two types of SG inhibitory peptides (SIPs) derived from SG core proteins Caprin1 and USP10 and fused with cell-penetrating peptides to generate TAT-SIP-C1/2 and SIP-U1-Antp, respectively. We obtained 11 SG-inducing anticancer compounds from cell-based screens and explored the potential application of SIPs in overcoming resistance to the SG-inducing anticancer drug sorafenib. We found that SIPs increased the sensitivity of HeLa cells to sorafenib via the disruption of SGs. Therefore, anticancer drugs which are competent to induce SGs could be combined with SIPs to sensitize cancer cells, which might provide a novel therapeutic strategy to alleviate anticancer drug resistance.

GZ17-6.02 kills PDX isolates of uveal melanoma.

GZ17-6.02 has undergone phase I evaluation in patients with solid tumors (NCT03775525). The RP2D is 375 mg PO BID, with an uveal melanoma patient exhibiting a 15% reduction in tumor mass for 5 months at this dose. Studies in this manuscript have defined the biology of GZ17-6.02 in PDX isolates of uveal melanoma cells. GZ17-6.02 killed uveal melanoma cells through multiple convergent signals including enhanced ATM-AMPK-mTORC1 activity, inactivation of YAP/TAZ and inactivation of eIF2α. GZ17-6.02 significantly enhanced the expression of BAP1, predictive to reduce metastasis, and reduced the levels of ERBB family RTKs, predicted to reduce growth. GZ17-6.02 interacted with doxorubicin or ERBB family inhibitors to significantly enhance tumor cell killing which was associated with greater levels of autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5 or eIF2α were more protective than knock down of ATM, AMPKα, CD95 or FADD, however, over-expression of FLIP-s provided greater protection compared to knock down of CD95 or FADD. Expression of activated forms of mTOR and STAT3 significantly reduced tumor cell killing. GZ17-6.02 reduced the expression of PD-L1 in uveal melanoma cells to a similar extent as observed in cutaneous melanoma cells whereas it was less effective at enhancing the levels of MHCA. The components of GZ17-6.02 were detected in tumors using a syngeneic tumor model. Our data support future testing GZ17-6.02 in uveal melanoma as a single agent, in combination with ERBB family inhibitors, in combination with cytotoxic drugs, or with an anti-PD1 immunotherapy.

Proteostatic reactivation of the developmental transcription factor TBX3 drives BRAF/MAPK-mediated tumorigenesis.

MAPK pathway-driven tumorigenesis, often induced by BRAFV600E, relies on epithelial dedifferentiation. However, how lineage differentiation events are reprogrammed remains unexplored. Here, we demonstrate that proteostatic reactivation of developmental factor, TBX3, accounts for BRAF/MAPK-mediated dedifferentiation and tumorigenesis. During embryonic development, BRAF/MAPK upregulates USP15 to stabilize TBX3, which orchestrates organogenesis by restraining differentiation. The USP15-TBX3 axis is reactivated during tumorigenesis, and Usp15 knockout prohibits BRAFV600E-driven tumor development in a Tbx3-dependent manner. Deleting Tbx3 or Usp15 leads to tumor redifferentiation, which parallels their overdifferentiation tendency during development, exemplified by disrupted thyroid folliculogenesis and elevated differentiation factors such as Tpo, Nis, Tg. The clinical relevance is highlighted in that both USP15 and TBX3 highly correlates with BRAFV600E signature and poor tumor prognosis. Thus, USP15 stabilized TBX3 represents a critical proteostatic mechanism downstream of BRAF/MAPK-directed developmental homeostasis and pathological transformation, supporting that tumorigenesis largely relies on epithelial dedifferentiation achieved via embryonic regulatory program reinitiation.

Performance of glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) biomarkers in predicting CT scan results and neurological outcomes in children with traumatic brain injury (BRAINI-2 paediatric study): protocol of a European prospective multicentre study.

INTRODUCTION: In light of the burden of traumatic brain injury (TBI) in children and the excessive number of unnecessary CT scans still being performed, new strategies are needed to limit their use while minimising the risk of delayed diagnosis of intracranial lesions (ICLs). Identifying children at higher risk of poor outcomes would enable them to be better monitored. The use of the blood-based brain biomarkers glial fibrillar acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) could help clinicians in this decision. The overall aim of this study is to provide new knowledge regarding GFAP and UCH-L1 in order to improve TBI management in the paediatric population. METHODS AND ANALYSIS: We will conduct a European, prospective, multicentre study, the BRAINI-2 paediatric study, in 20 centres in France, Spain and Switzerland with an inclusion period of 30 months for a total of 2880 children and adolescents included. To assess the performance of GFAP and UCH-L1 used separately and in combination to predict ICLs on CT scans (primary objective), 630 children less than 18 years of age with mild TBI, defined by a Glasgow Coma Scale score of 13-15 and with a CT scan will be recruited. To evaluate the potential of GFAP and UCH-L1 in predicting the prognosis after TBI (secondary objective), a further 1720 children with mild TBI but no CT scan as well as 130 children with moderate or severe TBI will be recruited. Finally, to establish age-specific reference values for GFAP and UCH-L1 (secondary objective), we will include 400 children and adolescents with no history of TBI. ETHICS AND DISSEMINATION: This study has received ethics approval in all participating countries. Results from our study will be disseminated in international peer-reviewed journals. All procedures were developed in order to assure data protection and confidentiality. TRIAL REGISTRATION NUMBER: NCT05413499.

Evaluation of Neuromuscular Morphometry of the Vaginal Wall Using Protein Gene Product 9.5 (Pgp 9.5) and Smooth Muscle α-Actin (Sma) in Patients with Posterior Vaginal Wall Prolapse.

Background and Objectives: This study aims to compare the neuromuscular structure of the vagina in women with posterior vaginal wall prolapse with the neuromuscular structure of the vagina in women without prolapse, to determine the difference, and to demonstrate the role of neuromuscular structure in the physiopathology of prolapse. Materials and Methods: In this prospective study, women aged between 40 and 75 years who had not undergone any vaginal surgery and had not undergone any abdominal prolapse surgery were included. Thirty-one women diagnosed with rectocele on examination were included in the study group. Thirty-one patients who underwent vaginal intervention and hysterectomy for reasons other than rectocele (colposcopy, conization, etc.) without anterior or posterior wall prolapse were included in the control group. Biopsy material was obtained from the epithelium of the posterior wall of the vagina, including the fascia that fits the Ap point. Immunohistochemical staining with Protein Gene Product 9.5 and smooth muscle α-actin was performed in the pathology laboratory. The epithelial thickness measurement and smooth muscle density parameters obtained with these immunohistochemical stainings were compared between the two groups. The collected data were analyzed using the SPSS 23 package program. p values less than 0.05 were considered statistically significant. Results: In the control group, muscle thickness and the number of nerves per mm2 of fascia were statistically significantly higher than in the study group (p < 0.05). Conclusions: We found that smooth muscle tissue and the number of nerves per mm2 of fascia were decreased in posterior vaginal wall prolapse compared to the general population. Based on the correlation coefficients, age was the parameter that most affected the degree of prolapse, followed by parity, number of live births, and number of vaginal deliveries.

Usp14 deficiency removes α-synuclein by regulating S100A8/A9 in Parkinson's disease.

Ubiquitin-proteasome system dysfunction triggers α-synuclein aggregation, a hallmark of neurodegenerative diseases, such as Parkinson's disease (PD). However, the crosstalk between deubiquitinating enzyme (DUBs) and α-synuclein pathology remains unclear. In this study, we observed a decrease in the level of ubiquitin-specific protease 14 (USP14), a DUB, in the cerebrospinal fluid (CSF) of PD patients, particularly females. Moreover, CSF USP14 exhibited a dual correlation with α-synuclein in male and female PD patients. To investigate the impact of USP14 deficiency, we crossed USP14 heterozygous mouse (USP14+/-) with transgenic A53T PD mouse (A53T-Tg) or injected adeno-associated virus (AAV) carrying human α-synuclein (AAV-hα-Syn) in USP14+/- mice. We found that Usp14 deficiency improved the behavioral abnormities and pathological α-synuclein deposition in female A53T-Tg or AAV-hα-Syn mice. Additionally, Usp14 inactivation attenuates the pro-inflammatory response in female AAV-hα-Syn mice, whereas Usp14 inactivation demonstrated opposite effects in male AAV-hα-Syn mice. Mechanistically, the heterodimeric protein S100A8/A9 may be the downstream target of Usp14 deficiency in female mouse models of α-synucleinopathies. Furthermore, upregulated S100A8/A9 was responsible for α-synuclein degradation by autophagy and the suppression of the pro-inflammatory response in microglia after Usp14 knockdown. Consequently, our study suggests that USP14 could serve as a novel therapeutic target in PD.

The Emerging Role of Ubiquitin-Specific Protease 36 (USP36) in Cancer and Beyond.

The balance between ubiquitination and deubiquitination is instrumental in the regulation of protein stability and maintenance of cellular homeostasis. The deubiquitinating enzyme, ubiquitin-specific protease 36 (USP36), a member of the USP family, plays a crucial role in this dynamic equilibrium by hydrolyzing and removing ubiquitin chains from target proteins and facilitating their proteasome-dependent degradation. The multifaceted functions of USP36 have been implicated in various disease processes, including cancer, infections, and inflammation, via the modulation of numerous cellular events, including gene transcription regulation, cell cycle regulation, immune responses, signal transduction, tumor growth, and inflammatory processes. The objective of this review is to provide a comprehensive summary of the current state of research on the roles of USP36 in different pathological conditions. By synthesizing the findings from previous studies, we have aimed to increase our understanding of the mechanisms underlying these diseases and identify potential therapeutic targets for their treatment.

Nerve Bundle Density and Expression of NGF and IL-1ß Are Intra-Individually Heterogenous in Subtypes of Endometriosis.

Endometriosis is a gynecological disorder associated with local inflammation and neuroproliferation. Increased nerve bundle density has been attributed to increased expression of nerve growth factor (NGF) and interleukin-1ß (IL-1ß). Immunohistochemical analysis was carried out on 12 patients presenting with all three anatomic subtypes of endometriosis (deep, superficial peritoneal, endometrioma) at surgery, with at least two surgically excised subtypes available for analysis. Immunolocalization for nerve bundle density around endometriosis using protein gene product 9.5 (PGP9.5), as well as NGF and IL-1ß histoscores in endometriosis epithelium/stroma, was performed to evaluate differences in scores between lesions and anatomic subtypes per patient. Intra-individual heterogeneity in scores across lesions was assessed using the coefficient of variation (CV). The degree of score variability between subtypes was evaluated using the percentage difference between mean scores from one subtype to another subtype for each marker. PGP9.5 nerve bundle density was heterogenous across multiple subtypes of endometriosis, ranging from 50.0% to 173.2%, where most patients (8/12) showed CV ≥ 100%. The percentage difference in scores showed that PGP9.5 nerve bundle density and NGF and IL-1ß expression were heterogenous between anatomic subtypes within the same patient. Based on these observations of intra-individual heterogeneity, we conclude that markers of neuroproliferation in endometriosis should be stratified by anatomic subtype in future studies of clinical correlation.

Targeting the Plasmodium falciparum UCHL3 ubiquitin hydrolase using chemically constrained peptides.

The ubiquitin-proteasome system is essential to all eukaryotes and has been shown to be critical to parasite survival as well, including Plasmodium falciparum, the causative agent of the deadliest form of malarial disease. Despite the central role of the ubiquitin-proteasome pathway to parasite viability across its entire life-cycle, specific inhibitors targeting the individual enzymes mediating ubiquitin attachment and removal do not currently exist. The ability to disrupt P. falciparum growth at multiple developmental stages is particularly attractive as this could potentially prevent both disease pathology, caused by asexually dividing parasites, as well as transmission which is mediated by sexually differentiated parasites. The deubiquitinating enzyme PfUCHL3 is an essential protein, transcribed across both human and mosquito developmental stages. PfUCHL3 is considered hard to drug by conventional methods given the high level of homology of its active site to human UCHL3 as well as to other UCH domain enzymes. Here, we apply the RaPID mRNA display technology and identify constrained peptides capable of binding to PfUCHL3 with nanomolar affinities. The two lead peptides were found to selectively inhibit the deubiquitinase activity of PfUCHL3 versus HsUCHL3. NMR spectroscopy revealed that the peptides do not act by binding to the active site but instead block binding of the ubiquitin substrate. We demonstrate that this approach can be used to target essential protein-protein interactions within the Plasmodium ubiquitin pathway, enabling the application of chemically constrained peptides as a novel class of antimalarial therapeutics.

USP9X-mediated REV1 deubiquitination promotes lung cancer radioresistance via the action of REV1 as a Rad18 molecular scaffold for cystathionine γ-lyase.

BACKGROUND: Radioresistance is a key clinical constraint on the efficacy of radiotherapy in lung cancer patients. REV1 DNA directed polymerase (REV1) plays an important role in repairing DNA damage and maintaining genomic stability. However, its role in the resistance to radiotherapy in lung cancer is not clear. This study aims to clarify the role of REV1 in lung cancer radioresistance, identify the intrinsic mechanisms involved, and provide a theoretical basis for the clinical translation of this new target for lung cancer treatment. METHODS: The effect of targeting REV1 on the radiosensitivity was verified by in vivo and in vitro experiments. RNA sequencing (RNA-seq) combined with nontargeted metabolomics analysis was used to explore the downstream targets of REV1. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify the content of specific amino acids. The coimmunoprecipitation (co-IP) and GST pull-down assays were used to validate the interaction between proteins. A ubiquitination library screening system was constructed to investigate the regulatory proteins upstream of REV1. RESULTS: Targeting REV1 could enhance the radiosensitivity in vivo, while this effect was not obvious in vitro. RNA sequencing combined with nontargeted metabolomics revealed that the difference result was related to metabolism, and that the expression of glycine, serine, and threonine (Gly/Ser/Thr) metabolism signaling pathways was downregulated following REV1 knockdown. LC-MS/MS demonstrated that REV1 knockdown results in reduced levels of these three amino acids and that cystathionine γ-lyase (CTH) was the key to its function. REV1 enhances the interaction of CTH with the E3 ubiquitin ligase Rad18 and promotes ubiquitination degradation of CTH by Rad18. Screening of the ubiquitination compound library revealed that the ubiquitin-specific peptidase 9 X-linked (USP9X) is the upstream regulatory protein of REV1 by the ubiquitin-proteasome system, which remodels the intracellular Gly/Ser/Thr metabolism. CONCLUSION: USP9X mediates the deubiquitination of REV1, and aberrantly expressed REV1 acts as a scaffolding protein to assist Rad18 in interacting with CTH, promoting the ubiquitination and degradation of CTH and inducing remodeling of the Gly/Ser/Thr metabolism, which leads to radioresistance. A novel inhibitor of REV1, JH-RE-06, was shown to enhance lung cancer cell radiosensitivity, with good prospects for clinical translation.

The Suppression of Ubiquitin C-Terminal Hydrolase L1 Promotes the Transdifferentiation of Auditory Supporting Cells into Hair Cells by Regulating the mTOR Pathway.

In mammals, hearing loss is irreversible due to the lack of the regenerative capacity of the auditory epithelium. However, stem/progenitor cells in mammalian cochleae may be a therapeutic target for hearing regeneration. The ubiquitin proteasome system plays an important role in cochlear development and maintenance. In this study, we investigated the role of ubiquitin C-terminal hydrolase L1 (UCHL1) in the process of the transdifferentiation of auditory supporting cells (SCs) into hair cells (HCs). The expression of UCHL1 gradually decreased as HCs developed and was restricted to inner pillar cells and third-row Deiters' cells between P2 and P7, suggesting that UCHL1-expressing cells are similar to the cells with Lgr5-positive progenitors. UCHL1 expression was decreased even under conditions in which supernumerary HCs were generated with a γ-secretase inhibitor and Wnt agonist. Moreover, the inhibition of UCHL1 by LDN-57444 led to an increase in HC numbers. Mechanistically, LDN-57444 increased mTOR complex 1 activity and allowed SCs to transdifferentiate into HCs. The suppression of UCHL1 induces the transdifferentiation of auditory SCs and progenitors into HCs by regulating the mTOR pathway.

Hypoxic adipose stem cell-derived exosomes carrying high-abundant USP22 facilitate cutaneous wound healing through stabilizing HIF-1α and upregulating lncRNA H19.

Hypoxic preconditioning has been recognized as a promotive factor for accelerating cutaneous wound healing. Our previous study uncovered that exosomal lncRNA H19, derived from adipose-derived stem cells (ADSCs), plays a crucial role in orchestrating cutaneous wound healing. Herein, we aimed to explore whether there is a connection between hypoxia and ADSC-derived exosomes (ADSCs-exos) in cutaneous wound healing. Exosomes extracted from ADSCs under normoxic and hypoxic conditions were identified using transmission electron microscope (TEM) and particle size analysis. The effects of ADSCs-exos on the proliferation, migration, and angiogenesis of human umbilical vein endothelial cells (HUVECs) were evaluated by CCK-8, EdU, wound healing, and tube formation assays. Expression patterns of H19, HIF-1α, and USP22 were measured. Co-immunoprecipitation, chromatin immunoprecipitation, ubiquitination, and luciferase reporter assays were conducted to confirm the USP22/HIF-1α/H19 axis, which was further validated in a mice model of skin wound. Exosomes extracted from hypoxia-treated ADSCs (termed as H-ADSCs-exos) significantly increased cell proliferation, migration, and angiogenesis in H2O2-exposed HUVECs, and promoted cutaneous wound healing in vivo. Moreover, H-ADSCs and H-ADSCs-exos, which exhibited higher levels of H19, were found to be transcriptionally activated by HIF-1α. Mechanically, H-ADSCs carrying USP22 accounted for deubiquitinating and stabilizing HIF-1α. Additionally, H-ADSCs-exos improved cell proliferation, migration, and angiogenesis in H2O2-triggered HUVECs by activating USP22/HIF-1α axis and promoting H19 expression, which may provide a new clue for the clinical treatment of cutaneous wound healing.

Deficiency of UCHL1 results in insufficient decidualization accompanied by impaired dNK modulation and eventually miscarriage.

BACKGROUND: Miscarriage is a frustrating complication of pregnancy that is common among women of reproductive age. Insufficient decidualization which not only impairs embryo implantation but disturbs fetomaternal immune-tolerance, has been widely regarded as a major cause of miscarriage; however, the underlying mechanisms resulting in decidual impairment are largely unknown. METHODS: With informed consent, decidual tissue from patients with spontaneous abortion or normal pregnant women was collected to detect the expression profile of UCHL1. Human endometrial stromal cells (HESCs) were used to explore the roles of UCHL1 in decidualization and dNK modulation, as well as the mechanisms involved. C57/BL6 female mice (7-10 weeks old) were used to construct pregnancy model or artificially induced decidualization model to evaluate the effect of UCHL1 on mice decidualization and pregnancy outcome. RESULTS: The Ubiquitin C-terminal hydrolase L1 (UCHL1), as a deubiquitinating enzyme, was significantly downregulated in decidua from patients with miscarriage, along with impaired decidualization and decreased dNKs. Blockage of UCHL1 led to insufficient decidualization and resultant decreased expression of cytokines CXCL12, IL-15, TGF-ß which were critical for generation of decidual NK cells (dNKs), whereas UCHL1 overexpression enhanced decidualization accompanied by increase in dNKs. Mechanistically, the promotion of UCHL1 on decidualization was dependent on its deubiquitinating activity, and intervention of UCHL1 inhibited the activation of JAK2/STAT3 signaling pathway, resulting in aberrant decidualization and decreased production of cytokines associated with dNKs modulation. Furthermore, we found that inhibition of UCHL1 also disrupted the decidualization in mice and eventually caused adverse pregnancy outcome. CONCLUSIONS: UCHL1 plays significant roles in decidualization and dNKs modulation during pregnancy in both humans and mice. Its deficiency indicates a poor pregnancy outcome due to defective decidualization, making UCHL1 a potential target for the diagnosis and treatment of miscarriage.

USP18 Curbs the Progression of Metabolic Hypertension by Suppressing JAK/STAT Pathway.

Hypertension is a pathological state of the metabolic syndrome that increases the risk of cardiovascular disease. Managing hypertension is challenging, and we aimed to identify the pathogenic factors and discern therapeutic targets for metabolic hypertension (MHR). An MHR rat model was established with the combined treatment of a high-sugar, high-fat diet and ethanol. Histopathological observations were performed using hematoxylin-eosin and Sirius Red staining. Transcriptome sequencing was performed to screen differentially expressed genes. The role of ubiquitin-specific protease 18 (USP18) in the proliferation, apoptosis, and oxidative stress of HUVECs was explored using Cell Counting Kit-8, flow cytometry, and enzyme-linked immunosorbent assays. Moreover, USP18 downstream signaling pathways in MHR were screened, and the effects of USP18 on these signaling pathways were investigated by western blotting. In the MHR model, total cholesterol and low-density lipoprotein levels increased, while high-density lipoprotein levels decreased. Moreover, high vessel thickness and percentage of collagen were noted along with increased malondialdehyde, decreased superoxide dismutase and catalase levels. The staining results showed that the MHR model exhibited an irregular aortic intima and disordered smooth muscle cells. There were 78 differentially expressed genes in the MHR model, and seven hub genes, including USP18, were identified. USP18 overexpression facilitated proliferation and reduced apoptosis and oxidative stress in HUVECs treated with Ang in vitro. In addition, the JAK/STAT pathway was identified as a USP18 downstream signaling pathway, and USP18 overexpression inhibited the expression of JAK/STAT pathway-related proteins. Conclusively, USP18 restrained MHR progression by promoting cell proliferation, reversing apoptosis and oxidative stress, and suppressing the JAK/STAT pathway.