Cleavage of Stau2 by 3C protease promotes EV-A71 replication.

BACKGROUND: Enterovirus A71 (EV-A71), as a neurotropic virus, mainly affects infants and young children under the age of 5. EV-A71 infection causes hand-foot-mouth disease and herpetic angina, and even life-threatening neurological complications. However, the molecular mechanism by which EV-A71 induces nervous system damage remains elusive. The viral protease 3C plays an important role during EV-A71 infection and is also a key intersection of virus-host interactions. Previously, we used yeast two-hybrid to screen out the host protein Double-stranded RNA-binding protein Staufen homolog 2 (Stau2), an important member involved in neuronal mRNA transport, potentially interacts with 3C. METHODS: We used coimmunoprecipitation (Co-IP) and immunofluorescence assay (IFA) to confirm that EV-A71 3C interacts with Stau2. By constructing the mutant of Stau2, we found the specific site where the 3C protease cleaves Stau2. Detection of VP1 protein using Western blotting characterized EV-A71 viral replication, and overexpression or knockdown of Stau2 exhibited effects on EV-A71 replication. The effect of different cleavage products on EV-A71 replication was demonstrated by constructing Stau2 truncates. RESULTS: In this study, we found that EV-A71 3C interacts with Stau2. Stau2 is cleaved by 3C at the Q507-G508 site. Overexpression of Stau2 promotes EV-A71 VP1 protein expression, whereas depletion of Stau2 by small interfering RNA inhibits EV-A71 replication. Stau2 is essential for EV-A71 replication, and the product of Stau2 cleavage by 3C, 508-570 aa, has activity that promotes EV-A71 replication. In addition, we found that mouse Stau2 is also cleaved by EV-A71 3C at the same site. CONCLUSIONS: Our research provides an example for EV-A71-host interaction, enriching key targets of host factors that contribute to viral replication.

Ultraviolet irradiation enhances the nitration of allergens.

Ultraviolet (UV) light is widely used for disinfection in indoor environments. Some wavelengths of UV light can produce high concentration of O3. UV irradiation combined with O3 may have great potential for nitration of allergens in the presence of NO2 in the air. In this study, the effects of UV irradiation on the nitration of three major indoor allergens including group Ⅰ allergens of house dust mite (Der p 1 and Der f 1) and group Ⅰ allergen of dog (Can f 1) in the presence of NO2 and O3 were investigated by analysis of the protein quantity, tyrosine, peptides, and nitration degree. The results showed that UV irradiation induced a significant increase in the quantity of 3-nitrotyrosine in the allergens from 0.4 ± 0.4 ng to 4.0 ± 0.8 ng. After 12 h of UV-O3 co-exposure, the total nitration degrees of the three allergens ranged from 0.1% to 0.5%, which were significantly higher than those after only O3 exposure (p < 0.05). The analysis of peptides revealed that the nitration of tyrosine was site-specific. The tyrosine Y231, which was adjacent to aspartic acid, posed the highest nitration degree of 41.1 ± 24.0% in Der p 1. The nitration degree of tyrosine Y162 was the highest (1.7 ± 0.1%) in Der f 1. Overall, this study demonstrated that UV irradiation enhanced the O3-related nitration of allergens in the air, which provides an experimental basis for the impact of daily disinfection behavior on allergens.

CircSEC24B activates autophagy and induces chemoresistance of colorectal cancer via OTUB1-mediated deubiquitination of SRPX2.

Circular RNAs (circRNAs) are a type of regulatory RNA that feature covalently closed single-stranded loops. Evidence suggested that circRNAs play important roles in the progression and development of various cancers. However, the impact of circRNA on autophagy-mediated progression of colorectal cancer (CRC) remains unclear. The objective of this project was to investigate the influence of circSEC24B on autophagy and its underlying mechanisms in CRC. To validate the presence and circular structure of circSEC24B in CRC cells and tissues, PCR and Sanger sequencing techniques were employed. Drug resistance and invasive phenotype of CRC cells were evaluated using CCK8, transwell, and Edu assays. Gain- and loss-of-function experiments were conducted to assess the effects of circSEC24B and its protein partner on the growth, invasion, and metastasis of CRC cells in vitro and in vivo. Interactions between circSEC24B, OTUB1, and SRPX2 were analyzed through immunofluorescence, RNA-pulldown, and RIP assays. Mass spectrometry analysis was used to identify potential binding proteins of circRNA in CRC cells. Vectors were constructed to investigate the specific structural domain of the deubiquitinating enzyme OTUB1 that binds to circSEC24B. Results showed that circSEC24B expression was increased in CRC tissues and cell lines, and it enhanced CRC cell proliferation and autophagy levels. Mechanistically, circSEC24B promoted CRC cell proliferation by regulating the protein stability of SRPX2. Specifically, circSEC24B acted as a scaffold, facilitating the binding of OTUB1 to SRPX2 and thereby enhancing its protein stability. Additionally, evidence suggested that OTUB1 regulated SRPX2 expression through an acetylation-dependent mechanism. In conclusion, this study demonstrated that circSEC24B activated autophagy and induced chemoresistance in CRC by promoting the deubiquitination of SRPX2, mediated by the deubiquitinating enzyme OTUB1.

Structure Activity of ß-Amidomethyl Vinyl Sulfones as Covalent Inhibitors of Chikungunya nsP2 Cysteine Protease with Antialphavirus Activity.

Despite their widespread impact on human health, there are no approved drugs for combating alphavirus infections. The heterocyclic ß-aminomethyl vinyl sulfone RA-0002034 (1a) is a potent irreversible covalent inhibitor of the alphavirus nsP2 cysteine protease with broad-spectrum antiviral activity. Analogs of 1a that varied each of the three regions of the molecule were synthesized to establish structure-activity relationships for the inhibition of Chikungunya (CHIKV) nsP2 protease and viral replication. The vinyl sulfone covalent warhead was highly sensitive to modifications. However, alterations to the core five-membered heterocycle and aryl substituent were well tolerated. The 5-(2,5-dimethoxyphenyl)pyrazole (1o) and 4-cyanopyrazole (8d) analogs exhibited kinact/Ki ratios >9000 M-1 s-1. 3-Arylisoxazole (10) was identified as an isosteric replacement for the five-membered heterocycle, which circumvented the intramolecular cyclization of pyrazole-based inhibitors like 1a. A ligand-based model of the enzyme active site was developed to aid the design of nsP2 protease inhibitors as potential therapeutics against alphaviruses.

Inhibitor of the non-structural protein 2 protease shows promising efficacy in mouse models of chikungunya.

Chikungunya virus (CHIKV) is responsible for the most endemic alphavirus infections called Chikungunya. The endemicity of Chikungunya has increased over the past two decades, and it is a pathogen with pandemic potential. There is currently no approved direct-acting antiviral to treat the disease. As part of our antiviral drug discovery program focused on alphaviruses and the non-structural protein 2 protease, we discovered that J12 and J13 can inhibit CHIKV nsP2 protease and block the replication of CHIKV in cell cultures. Both compounds are metabolically stable to human liver microsomal and S9 enzymes. J13 has excellent oral bioavailability in pharmacokinetics studies in mice and ameliorated Chikungunya symptoms in preliminary efficacy studies in mice. J13 exhibited an excellent safety profile in in vitro safety pharmacology and off-target screening assays, making J13 and its analogs good candidates for drug development against Chikungunya.

Elucidating the Substrate Envelope of Enterovirus 68-3C Protease: Structural Basis of Specificity and Potential Resistance.

Enterovirus-D68 (EV68) has emerged as a global health concern over the last decade with severe symptomatic infections resulting in long-lasting neurological deficits and death. Unfortunately, there are currently no FDA-approved antiviral drugs for EV68 or any other non-polio enterovirus. One particularly attractive class of potential drugs are small molecules inhibitors, which can target the conserved active site of EV68-3C protease. For other viral proteases, we have demonstrated that the emergence of drug resistance can be minimized by designing inhibitors that leverage the evolutionary constraints of substrate specificity. However, the structural characterization of EV68-3C protease bound to its substrates has been lacking. Here, we have determined the substrate specificity of EV68-3C protease through molecular modeling, molecular dynamics (MD) simulations, and co-crystal structures. Molecular models enabled us to successfully characterize the conserved hydrogen-bond networks between EV68-3C protease and the peptides corresponding to the viral cleavage sites. In addition, co-crystal structures we determined have revealed substrate-induced conformational changes of the protease which involved new interactions, primarily surrounding the S1 pocket. We calculated the substrate envelope, the three-dimensional consensus volume occupied by the substrates within the active site. With the elucidation of the EV68-3C protease substrate envelope, we evaluated how 3C protease inhibitors, AG7088 and SG-85, fit within the active site to predict potential resistance mutations.

USP26 as a hepatitis B virus-induced deubiquitinase primes hepatocellular carcinogenesis by epigenetic remodeling.

Despite recent advances in systemic therapy for hepatocellular carcinoma (HCC), the prognosis of hepatitis B virus (HBV)-induced HCC patients remains poor. By screening a sgRNA library targeting human deubiquitinases, we find that ubiquitin-specific peptidase 26 (USP26) deficiency impairs HBV-positive HCC cell proliferation. Genetically engineered murine models with Usp26 knockout confirm that Usp26 drives HCC tumorigenesis. Mechanistically, we find that the HBV-encoded protein HBx binds to the promoter and induces the production of USP26, which is an X-linked gene exclusively expressed in the testis. HBx consequently promotes the association of USP26 with SIRT1 to synergistically stabilize SIRT1 by deubiquitination, which promotes cell proliferation and impedes cell apoptosis to accelerate HCC tumorigenesis. In patients with HBV-positive HCC, USP26 is robustly induced, and its levels correlate with SIRT1 levels and poor prognosis. Collectively, our study highlights a causative link between HBV infection, deubiquitinase induction and development of HCC, identifying a druggable target, USP26.

Genetic trans-complementation of L-protease fails to rescue the infectious foot-and-mouth disease virus from the Lbpro defective genome.

Outbreaks of the foot-and-mouth disease (FMD) have major economic impact on the global livestock industry by affecting the animal health and product safety. L-protease, a non-structural protein of FMDV, is a papain-like cysteine proteinase involved in viral protein processing as well as cleavage of host proteins for promoting the virus growth. FMDV synthesizes two forms of leader proteinase, Lpro (Labpro and Lbpro), where the deletion of Labpro is lethal and Lbpro deletion is reported to be attenuated. Defective replicons have been used by trans-complementing the deleted gene to produce one time replicating virus; thus, the bio-safety procedure can be compromised in the production units. Attempts are made to rescue of ΔLbproFMDV Asia1 virus by co-expressing the Lbpro protein carried in pcDNA plasmid. Mutant FMDV cDNA, pAsia-ΔLbpro, was constructed by PCR mediated mutagenesis using inverse primers. Transfection of BHK-21 cells with in-vitro transcribed RNA from the constructs failed to produce an infective mutant FMDV. Genetic trans-complementation of the Lbpro, which was done by co-transfecting the pcDNALbpro plasmid DNA along with the pAsia-ΔLbpro RNA in BHK-21 cells also failed to produce viable virus. Expression experiments of reporter genes and indirect immune-fluorescence confirmed the production of the viral proteins in wild type FMDV pAsiaWT; however, it was absent in the pAsia-ΔLbpro indicating that the leaderless virus was unable to produce infectious progeny and infect the cells. Failure to produce virus either by Lbpro deleted mutant clone or by genetic complementation suggests little chance of reversion of the disabled virus with large deletions of FMDV genome.

TDP-43 regulates LC3ylation in neural tissue through ATG4B cryptic splicing inhibition.

Amyotrophic lateral sclerosis (ALS) is an adult-onset motor neuron disease with a mean survival time of three years. The 97% of the cases have TDP-43 nuclear depletion and cytoplasmic aggregation in motor neurons. TDP-43 prevents non-conserved cryptic exon splicing in certain genes, maintaining transcript stability, including ATG4B, which is crucial for autophagosome maturation and Microtubule-associated proteins 1A/1B light chain 3B (LC3B) homeostasis. In ALS mice (G93A), Atg4b depletion worsens survival rates and autophagy function. For the first time, we observed an elevation of LC3ylation in the CNS of both ALS patients and atg4b-/- mouse spinal cords. Furthermore, LC3ylation modulates the distribution of ATG3 across membrane compartments. Antisense oligonucleotides (ASOs) targeting cryptic exon restore ATG4B mRNA in TARDBP knockdown cells. We further developed multi-target ASOs targeting TDP-43 binding sequences for a broader effect. Importantly, our ASO based in peptide-PMO conjugates show brain distribution post-IV administration, offering a non-invasive ASO-based treatment avenue for neurodegenerative diseases.

Sumo-regulatory SENP2 controls the homeostatic squamous mitosis-differentiation checkpoint.

Squamous or epidermoid cancer arises in stratified epithelia but also is frequent in the non-epidermoid epithelium of the lung by unclear mechanisms. A poorly studied mitotic checkpoint drives epithelial cells bearing irreparable genetic damage into epidermoid differentiation. We performed an RNA-sequencing gene search to target unknown regulators of this response and selected the SUMO regulatory protein SENP2. Alterations of SENP2 expression have been associated with some types of cancer. We found the protein to be strongly localised to mitotic spindles of freshly isolated human epidermal cells. Primary cells rapidly differentiated after silencing SENP2 with specific shRNAs. Loss of SENP2 produced in synchronised epithelial cells delays in mitotic entry and exit and defects in chromosomal alignment. The results altogether strongly argue for an essential role of SENP2 in the mitotic spindle and hence in controlling differentiation. In addition, the expression of SENP2 displayed an inverse correlation with the immuno-checkpoint biomarker PD-L1 in a pilot collection of aggressive lung carcinomas. Consistently, metastatic head and neck cancer cells that do not respond to the mitosis-differentiation checkpoint were resistant to depletion of SENP2. Our results identify SENP2 as a novel regulator of the epithelial mitosis-differentiation checkpoint and a potential biomarker in epithelial cancer.

The HtrA chaperone monitors sortase-assembled pilus biogenesis in Enterococcus faecalis.

Sortase-assembled pili contribute to virulence in many Gram-positive bacteria. In Enterococcus faecalis, the endocarditis and biofilm-associated pilus (Ebp) is polymerized on the membrane by sortase C (SrtC) and attached to the cell wall by sortase A (SrtA). In the absence of SrtA, polymerized pili remain anchored to the membrane (i.e. off-pathway). Here we show that the high temperature requirement A (HtrA) bifunctional chaperone/protease of E. faecalis is a quality control system that clears aberrant off-pathway pili from the cell membrane. In the absence of HtrA and SrtA, accumulation of membrane-bound pili leads to cell envelope stress and partially induces the regulon of the ceftriaxone resistance-associated CroRS two-component system, which in turn causes hyper-piliation and cell morphology alterations. Inactivation of croR in the OG1RF ΔsrtAΔhtrA background partially restores the observed defects of the ΔsrtAΔhtrA strain, supporting a role for CroRS in the response to membrane perturbations. Moreover, absence of SrtA and HtrA decreases basal resistance of E. faecalis against cephalosporins and daptomycin. The link between HtrA, pilus biogenesis and the CroRS two-component system provides new insights into the E. faecalis response to endogenous membrane perturbations.

Research progress of the Otubains subfamily in hepatocellular carcinoma.

In cancer research, oncogenesis can be affected by modulating the deubiquitination pathway. Ubiquitination regulates proteins post-translationally in variety of physiological processes. The Otubain Subfamily includes OTUB1 (ovarian tumor-associated proteinase B1) and OTUB2(ovarian tumor-associated proteinase B2). They are deubiquitinating enzymes, which are research hotspots in tumor immunotherapy, with their implications extending across the spectrum of tumor development. Understanding their important role in tumorigenesis, includ-ing hepatocellular carcinoma (HCC) is crucial. HCC has alarming global incidence rates and mortality statistics, ranking among the top five prevalent cancers in Malaysia1. Numerous studies have consistently indicated significant expression of OTUB1 and OTUB2 in HCC cells. In addition, OTUB1 has important biological functions in cancer, suggesting its important role in tumorigenesis. However, the mechanism underlying the action of OTUB1 and OTUB2 in liver cancer remains inadequately explored. Therefore, Otubain Subfamily, as potential molecular target, holds promise for advancing HCC treatments. However, further clinical studies are required to verify its efficacy and application prospects.

Foot-and-mouth disease virus (FMDV) negatively regulates ZFP36 protein expression to alleviate its antiviral activity.

Zinc finger protein 36 (ZFP36) is a key regulator of inflammatory and cytokine production. However, the interplay between swine zinc-finger protein 36 (sZFP36) and foot-and-mouth disease virus (FMDV) has not yet been reported. Here, we demonstrate that overexpression of sZFP36 restricted FMDV replication, while the knockdown of sZFP36 facilitated FMDV replication. To subvert the antagonism of sZFP36, FMDV decreased sZFP36 protein expression through its non-structural protein 3C protease (3Cpro). Our results also suggested that 3Cpro-mediated sZFP36 degradation was dependent on its protease activity. Further investigation revealed that both N-terminal and C-terminal-sZFP36 could be degraded by FMDV and FMDV 3Cpro. In addition, both N-terminal and C-terminal-sZFP36 decreased FMDV replication. Moreover, sZFP36 promotes the degradation of FMDV structural proteins VP3 and VP4 via the CCCH-type zinc finger and NES domains of sZFP36. Together, our results confirm that sZFP36 is a host restriction factor that negatively regulates FMDV replication.IMPORTANCEFoot-and-mouth disease (FMD) is an infectious disease of animals caused by the pathogen foot-and-mouth disease virus (FMDV). FMD is difficult to prevent and control because there is no cross-protection between its serotypes. Thus, we designed this study to investigate virus-host interactions. We first demonstrate that swine zinc-finger protein 36 (sZFP36) impaired FMDV structural proteins VP3 and VP4 to suppress viral replication. To subvert the antagonism of sZFP36, FMDV and FMDV 3Cpro downregulate sZFP36 expression to facilitate FMDV replication. Taken together, the present study reveals a previously unrecognized antiviral mechanism for ZFP36 and elucidates the role of FMDV in counteracting host antiviral activity.

Molecular basis for sortase-catalyzed pilus tip assembly.

During pilus assembly within the Gram-positive bacterial envelope, membrane-bound sortase enzymes sequentially crosslink specific pilus protein monomers through their cell wall sorting signals (CWSS), starting with a designated tip pilin, followed by the shaft made of another pilin, ultimately anchoring the fiber base pilin to the cell wall. To date, the molecular determinants that govern pilus tip assembly and the underlying mechanism remain unknown. Here, we addressed this in the model organism Actinomyces oris. This oral microbe assembles a pathogenically important pilus (known as type 2 fimbria) whose shafts, made of FimA pilins, display one of two alternate tip pilins-FimB or the coaggregation factor CafA-that share a markedly similar CWSS. We demonstrate that swapping the CWSS of CafA with that of FimB produces a functional hybrid, which localizes at the pilus tip and mediates polymicrobial coaggregation, whereas alanine-substitution of the conserved FLIAG motif within the CWSS hampers these processes. Remarkably, swapping the CWSS of the normal cell wall-anchored glycoprotein GspA with that of CafA promotes the assembly of hybrid GspA at the FimA pilus tip. Finally, exchanging the CWSS of the Corynebacterium diphtheriae shaft pilin SpaA with that of CafA leads to the FLIAG motif-dependent localization of the heterologous pilus protein SpaA at the FimA pilus tip in A. oris. Evidently, the CWSS and the FLIAG motif of CafA are both necessary and sufficient for its destination to the cognate pilus tip specifically assembled by a designated sortase in the organism. IMPORTANCE: Gram-positive pili, whose precursors harbor a cell wall sorting signal (CWSS) needed for sortase-mediated pilus assembly, typically comprise a pilus shaft and a tip adhesin. How a pilin becomes a pilus tip, nevertheless, remains undetermined. We demonstrate here in Actinomyces oris that the CWSS of the tip pilin CafA is necessary and sufficient to promote pilus tip assembly, and this functional assembly involves a conserved FLIAG motif within the CWSS. This is evidenced by the fact that an A. oris cell-wall anchored glycoprotein, GspA, or a heterologous shaft pilin from Corynebacterium diphtheriae, SpaA, engineered to have the CWSS of CafA in place of their CWSS, localizes at the pilus tip in a process that requires the FLIAG motif. Our findings provide the molecular basis for sortase-catalyzed pilus tip assembly that is very likely employed by other Gram-positive bacteria and potential bioengineering applications to display antigens at controlled surface distance.

Docosahexaenoic acid enhances the treatment efficacy for castration-resistant prostate cancer by inhibiting autophagy through Atg4B inhibition.

Autophagy induction in cancer is involved in cancer progression and the acquisition of resistance to anticancer agents. Therefore, autophagy is considered a potential therapeutic target in cancer therapy. In this study, we found that long-chain fatty acids (LCFAs) have inhibitory effects on Atg4B, which is essential for autophagosome formation, through screening based on the pharmacophore of 21f, a recently developed Atg4B inhibitor. Among these fatty acids, docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibited the most potent Atg4B inhibitory activity. DHA inhibited autophagy induced by androgen receptor signaling inhibitors (ARSI) in LNCaP and 22Rv1 prostate cancer cells and significantly increased apoptotic cell death. Furthermore, we investigated the effect of DHA on resistance to ARSI by establishing darolutamide-resistant prostate cancer 22Rv1 (22Rv1/Dar) cells, which had developed resistance to darolutamide, a novel ARSI. At baseline, 22Rv1/Dar cells showed a higher autophagy level than parental 22Rv1 cells. DHA significantly suppressed Dar-induced autophagy and sensitized 22Rv1/Dar cells by inducing apoptotic cell death through mitochondrial dysfunction. These results suggest that DHA supplementation may improve prostate cancer therapy with ARSI.

SRF SUMOylation modulates smooth muscle phenotypic switch and vascular remodeling.

Serum response factor (SRF) controls gene transcription in vascular smooth muscle cells (VSMCs) and regulates VSMC phenotypic switch from a contractile to a synthetic state, which plays a key role in the pathogenesis of cardiovascular diseases (CVD). It is not known how post-translational SUMOylation regulates the SRF activity in CVD. Here we show that Senp1 deficiency in VSMCs increased SUMOylated SRF and the SRF-ELK complex, leading to augmented vascular remodeling and neointimal formation in mice. Mechanistically, SENP1 deficiency in VSMCs increases SRF SUMOylation at lysine 143, reducing SRF lysosomal localization concomitant with increased nuclear accumulation and switching a contractile phenotype-responsive SRF-myocardin complex to a synthetic phenotype-responsive SRF-ELK1 complex. SUMOylated SRF and phospho-ELK1 are increased in VSMCs from coronary arteries of CVD patients. Importantly, ELK inhibitor AZD6244 prevents the shift from SRF-myocardin to SRF-ELK complex, attenuating VSMC synthetic phenotypes and neointimal formation in Senp1-deficient mice. Therefore, targeting the SRF complex may have a therapeutic potential for the treatment of CVD.

Sortase-Mediated Site-Specific Conjugation to Prepare Fluorine-18-Labeled Nanobodies.

Single-domain antibodies, or nanobodies (Nbs), are promising biomolecules for use in molecular imaging due to their excellent affinity, specificity, and fast clearance from the blood. Given their short blood half-life, pairing Nbs with short-lived imaging radioisotopes is desirable. Because fluorine-18 (18F) is routinely used for clinical imaging, it is an attractive radioisotope for Nbs. We report a novel sortase-based, site-specific 18F-labeling method applied to three nanobodies. Labeled nanobodies were synthesized either by a two-step indirect radiolabeling method in one pot or by a one-step direct labeling method using a sortase-mediated conjugation of either the radiolabeled chelator (H-GGGK((±)-Al[18F]FH3RESCA)-NH2) or the unlabeled chelator (H-GGGK((±)-H3RESCA)-NH2) followed by labeling with Al[18F]F, respectively. The overall radiochemical yields were 15-43% (n = 22, decay-corrected) in 70 min (indirect labeling) and 23-58% (n = 12, decay-corrected) in 50 min (direct labeling). The radiochemical purities of the labeled nanobodies prepared by both methods were >98% with a specific activity of 400-600 Ci/mmol (n = 22) for each of the three Nbs tested and exhibited excellent stability profiles under physiological conditions. This simple, site-specific, reproducible, and generalizable 18F-labeling method to prepare nanobodies (Nb-Al[18F]F-RESCA) or other low molecular weight biomolecules can easily be adopted in various settings for preclinical and clinical studies.

Suppression of SENP3 enhances macrophage alternative activation by mediating IRF4 de-SUMOylation in ESCC progression.

Esophageal cancer is common worldwide, with ESCC being the most frequent tumor in East Asia. Tumor-associated macrophages are an important component of the ESCC microenvironment. SUMOylation is a post-translational modification of proteins, and SUMO-specific proteases (SENPs) play an important role in de-SUMOylation. In human patients, we discovered that the levels of SENP3 were upregulated in the tumor-associated macrophages. Furthermore, the loss of SENP3 enhanced the alternative activation of macrophages in the 4-NQO-induced ESCC mice model. This is the first study to identify SENP3-mediated macrophage polarization via the de-SUMOylation of interferon regulatory factor 4 (IRF4) at the K349 site. Alternative activation of macrophages increases the migration and invasion potential of ESCC cells and promotes their progression in vivo. Moreover, patients with relatively low SENP3 expression in macrophages exhibit higher primary PET SUVmax value and lymph node metastasis rates. In summary, this study revealed that SENP3-mediated IRF4 de-SUMOylation is crucial for the alternative activation of macrophages and influences the progression of ESCC.

SENP1 reduces oxidative stress and apoptosis in renal ischaemia-reperfusion injury by deSUMOylation of HIF-1α.

Renal ischaemia-reperfusion injury (RIRI) is a primary cause of acute kidney damage, occurring frequently in situations like renal transplantation, yet the underlying mechanisms were not fully understood. Sentrin-specific protease 1 (SENP1) is an important member of the SENP family, which is widely involved in various diseases. However, the role of SENP1 in RIRI has been unclear. In our study, we discovered that SENP1 was involved in RIRI and reduced renal cell apoptosis and oxidative stress at elevated levels. Further mechanistic studies showed that hypoxia-inducible factor-1α (HIF-1α) was identified as a substrate of SENP1. Furthermore, SENP1 deSUMOylated HIF-1α, which reduced the degradation of HIF-1α, and exerted a renoprotective function. In addition, the protective function was lost after application of the HIF-1α specific inhibitor KC7F2. Briefly, our results fully demonstrated that SENP1 reduced the degradation of HIF-1α and attenuated oxidative stress and apoptosis in RIRI by regulating the deSUMOylation of HIF-1α, suggesting that SENP1 may serve as a potential therapeutic target for the treatment of RIRI.

Role of ATG4 Autophagy-Related Protein Family in the Lower Airways of Patients with Stable COPD.

Autophagy is a complex physiological pathway mediating homeostasis and survival of cells degrading damaged organelles and regulating their recycling. Physiologic autophagy can maintain normal lung function, decrease lung cellular senescence, and inhibit myofibroblast differentiation. It is well known that autophagy is activated in several chronic inflammatory diseases; however, its role in the pathogenesis of chronic obstructive pulmonary disease (COPD) and the expression of autophagy-related genes (ATGs) in lower airways of COPD patients is still controversial. The expression and localization of all ATG proteins that represented key components of the autophagic machinery modulating elongation, closure, and maturation of autophagosome membranes were retrospectively measured in peripheral lungs of patients with stable COPD (n = 10), control smokers with normal lung function (n = 10), and control nonsmoking subjects (n = 8) using immunohistochemical analysis. These results show an increased expression of ATG4 protein in alveolar septa and bronchiolar epithelium of stable COPD patients compared to smokers with normal lung function and non-smoker subjects. In particular, the genes in the ATG4 protein family (including ATG4A, ATG4B, ATG4C, and ATG4D) that have a key role in the modulation of the physiological autophagic machinery are the most important ATGs increased in the compartment of lower airways of stable COPD patients, suggesting that the alteration shown in COPD patients can be also correlated to impaired modulation of autophagic machinery modulating elongation, closure, and maturation of autophagosomes membranes. Statistical analysis was performed by the Kruskal-Wallis test and the Mann-Whitney U test for comparison between groups. A statistically significant increased expression of ATG4A (p = 0.0047), ATG4D (p = 0.018), and ATG5 (p = 0.019) was documented in the bronchiolar epithelium as well in alveolar lining for ATG4A (p = 0.0036), ATG4B (p = 0.0054), ATG4C (p = 0.0064), ATG4D (p = 0.0084), ATG5 (p = 0.0088), and ATG7 (p = 0.018) in patients with stable COPD compared to control groups. The ATG4 isoforms may be considered as additional potential targets for the development of new drugs in COPD.