CRISPR screening identifies the deubiquitylase ATXN3 as a PD-L1-positive regulator for tumor immune evasion.

Regulation of tumoral PD-L1 expression is critical to advancing our understanding of tumor immune evasion and the improvement of existing antitumor immunotherapies. Herein, we describe a CRISPR-based screening platform and identified ATXN3 as a positive regulator for PD-L1 transcription. TCGA database analysis revealed a positive correlation between ATXN3 and CD274 in more than 80% of human cancers. ATXN3-induced Pd-l1 transcription was promoted by tumor microenvironmental factors, including the inflammatory cytokine IFN-γ and hypoxia, through protection of their downstream transcription factors IRF1, STAT3, and HIF-2α. Moreover, ATXN3 functioned as a deubiquitinase of the AP-1 transcription factor JunB, indicating that ATNX3 promotes PD-L1 expression through multiple pathways. Targeted deletion of ATXN3 in cancer cells largely abolished IFN-γ- and hypoxia-induced PD-L1 expression and consequently enhanced antitumor immunity in mice, and these effects were partially reversed by PD-L1 reconstitution. Furthermore, tumoral ATXN3 suppression improved the preclinical efficacy of checkpoint blockade antitumor immunotherapy. Importantly, ATXN3 expression was increased in human lung adenocarcinoma and melanoma, and its levels were positively correlated with PD-L1 as well as its transcription factors IRF1 and HIF-2α. Collectively, our study identifies what we believe to be a previously unknown deubiquitinase, ATXN3, as a positive regulator for PD-L1 transcription and provides a rationale for targeting ATXN3 to sensitize checkpoint blockade antitumor immunotherapy.

Discovery of selective and potent USP22 inhibitors via structure-based virtual screening and bioassays exerting anti-tumor activity.

Ubiquitin-specific protease 22 (USP22) plays a prominent role in tumor development, invasion, metastasis and immune reprogramming, which has been proposed as a potential therapeutic target for cancer. Herein, we employed a structure-based discovery and biological evaluation and discovered that Rottlerin (IC50 = 2.53 µM) and Morusin (IC50 = 8.29 µM) and as selective and potent USP22 inhibitors. Treatment of HCT116 cells and A375 cells with each of the two compounds resulted in increased monoubiquitination of histones H2A and H2B, as well as reduced protein expression levels of Sirt1 and PD-L1, all of which are known as USP22 substrates. Additionally, our study demonstrated that the administration of Rottlerin or Morusin resulted in an increase H2Bub levels, while simultaneously reducing the expression of Sirt1 and PD-L1 in a manner dependent on USP22. Furthermore, Rottlerin and Morusin were found to enhance the degradation of PD-L1 and Sirt1, as well as increase the polyubiquitination of endogenous PD-L1 and Sirt1 in HCT116 cells. Moreover, in an in vivo syngeneic tumor model, Rottlerin and Morusin exhibited potent antitumor activity, which was accompanied by an enhanced infiltration of T cells into the tumor tissues. Using in-depth molecular dynamics (MD) and binding free energy calculation, conserved residue Leu475 and non-conserved residue Arg419 were proven to be crucial for the binding affinity and inhibitory function of USP22 inhibitors. In summary, our study established a highly efficient approach for USP22-specific inhibitor discovery, which lead to identification of two selective and potent USP22 inhibitors as potential drugs in anticancer therapy.

CircEPS15, as a sponge of MIR24-3p ameliorates neuronal damage in Parkinson disease through boosting PINK1-PRKN-mediated mitophagy.

Despite growing evidence that has declared the importance of circRNAs in neurodegenerative diseases, the clinical significance of circRNAs in dopaminergic (DA) neuronal degeneration in the pathogenesis of Parkinson disease (PD) remains unclear. Here, we performed rRNA-depleted RNA sequencing and detected more than 10,000 circRNAs in the plasma samples of PD patients. In consideration of ROC and the correlation between Hohen-Yahr stage (H-Y stage) and Unified Parkinson Disease Rating Scale-motor score (UPDRS) of 40 PD patients, circEPS15 was selected for further research. Low expression of circEPS15 was found in PD patients and there was a negative positive correlation between the circEPS15 level and severity of PD motor symptoms, while overexpression of circEPS15 protected DA neurons against neurotoxin-induced PD-like neurodegeneration in vitro and in vivo. Mechanistically, circEPS15 acted as a MIR24-3p sponge to promote the stable expression of target gene PINK1, thus enhancing PINK1-PRKN-dependent mitophagy to eliminate damaged mitochondria and maintain mitochondrial homeostasis. Thus, circEPS15 rescued DA neuronal degeneration through the MIR24-3p-PINK1 axis-mediated improvement of mitochondrial function. This study reveals that circEPS15 exerts a critical role in participating in PD pathogenesis, and may give us an insight into the novel avenue to develop potential biomarkers and therapeutic targets for PD.Abbreviations: AAV: adeno-associated virus; DA: dopaminergic; FISH: fluorescence in situ hybridizations; HPLC: high-performance liquid chromatography; H-Y stage: Hohen-Yahr stage; LDH: lactate dehydrogenase; MMP: mitochondrial membrane potential; MPTP/p: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid; NC: negative control; PD: Parkinson disease; PINK1: PTEN induced kinase 1; PBS: phosphate-buffered saline; ROS: reactive oxygen species; SNpc: substantia nigra pars compacta; TEM: transmission electron microscopy; UPDRS: Unified Parkinson's Disease Rating Scale-motor score.

Impeding the combination of astrocytic ASCT2 and NLRP3 by talniflumate alleviates neuroinflammation in experimental models of Parkinson's disease.

Alanine-serine-cysteine transporter 2 (ASCT2) is reported to participate in the progression of tumors and metabolic diseases. It is also considered to play a crucial role in the glutamate-glutamine shuttle of neuroglial network. However, it remains unclear the involvement of ASCT2 in neurological diseases such as Parkinson's disease (PD). In this study, we demonstrated that high expression of ASCT2 in the plasma samples of PD patients and the midbrain of MPTP mouse models is positively correlated with dyskinesia. We further illustrated that ASCT2 expressed in astrocytes rather than neurons significantly upregulated in response to either MPP+ or LPS/ATP challenge. Genetic ablation of astrocytic ASCT2 alleviated the neuroinflammation and rescued dopaminergic (DA) neuron damage in PD models in vitro and in vivo. Notably, the binding of ASCT2 to NLRP3 aggravates astrocytic inflammasome-triggered neuroinflammation. Then a panel of 2513 FDA-approved drugs were performed via virtual molecular screening based on the target ASCT2 and we succeed in getting the drug talniflumate. It is validated talniflumate impedes astrocytic inflammation and prevents degeneration of DA neurons in PD models. Collectively, these findings reveal the role of astrocytic ASCT2 in the pathogenesis of PD, broaden the therapeutic strategy and provide a promising candidate drug for PD treatment.

A deubiquitination module essential for Treg fitness in the tumor microenvironment.

The tumor microenvironment (TME) enhances regulatory T (Treg) cell stability and immunosuppressive functions through up-regulation of lineage transcription factor Foxp3, a phenomenon known as Treg fitness or adaptation. Here, we characterize previously unknown TME-specific cellular and molecular mechanisms underlying Treg fitness. We demonstrate that TME-specific stressors including transforming growth factor-ß (TGF-ß), hypoxia, and nutrient deprivation selectively induce two Foxp3-specific deubiquitinases, ubiquitin-specific peptidase 22 (Usp22) and Usp21, by regulating TGF-ß, HIF, and mTOR signaling, respectively, to maintain Treg fitness. Simultaneous deletion of both USPs in Treg cells largely diminishes TME-induced Foxp3 up-regulation, alters Treg metabolic signatures, impairs Treg-suppressive function, and alleviates Treg suppression on cytotoxic CD8+ T cells. Furthermore, we developed the first Usp22-specific small-molecule inhibitor, which dramatically reduced intratumoral Treg Foxp3 expression and consequently enhanced antitumor immunity. Our findings unveil previously unappreciated mechanisms underlying Treg fitness and identify Usp22 as an antitumor therapeutic target that inhibits Treg adaptability in the TME.

Targeting microglial NLRP3 in the SNc region as a promising disease-modifying therapy for Parkinson's disease.

INTRODUCTION: Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive loss of dopaminergic (DA) neurons. Accumulating evidence has shown that activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome is an early and cardinal feature in PD progression. Nevertheless, little is known about the effect of NLRP3 in the substantia nigra pars compacta (SNc) on DA neurodegeneration. METHODS AND RESULTS: In the present study, we constructed NLRP3 interference sequences wrapped by lentivirus (LV3-siNlrp3) to facilitate NLRP3 knockdown in the SNc region by intracerebral stereotactic injection. Then, we explored the effects of NLPR3 knockdown on PD pathologies via behavioral monitoring, immunohistochemistry and western blot analysis in acute 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) mouse model. Moreover, we performed in vitro experiments to investigate the effect of microglial NLRP3 knockdown on DA neuron survival in the context of 1-methyl-4-phenylpyridinium (MPP+ ) stimulation. Our results demonstrated that NLRP3 knockdown in the SNc region significantly improved MPTP-induced dyskinesia, DA neuronal loss and microglia activation in vivo. Meanwhile, knockdown of microglial NLRP3 attenuated MPP+ -induced DA neuronal damage in an indirect coculture system in which neurons were cultured in microglial conditional medium. Cumulatively, these data reveal that microglial NLRP3 located in the SNc region is detrimental to DA neurons survival, and knockdown of microglial NLRP3 is a potential strategy to rescue DA neurons in the progression of PD. CONCLUSIONS: This work demonstrates the role of NLRP3 in PD pathogenesis via microglia-neuron communication, and sheds light on targeting microglial NLRP3 to develop disease-modifying therapy for PD.

ß-Arrestin2-biased Drd2 agonist UNC9995 alleviates astrocyte inflammatory injury via interaction between ß-arrestin2 and STAT3 in mouse model of depression.

BACKGROUND: Major depressive disorder (MDD) is a prevalent and devastating psychiatric illness. Unfortunately, the current therapeutic practice, generally depending on the serotonergic system for drug treatment is unsatisfactory and shows intractable side effects. Multiple evidence suggests that dopamine (DA) and dopaminergic signals associated with neuroinflammation are highly involved in the pathophysiology of depression as well as in the mechanism of antidepressant drugs, which is still in the early stage of study and well worthy of investigation. METHODS: We established two chronic stress models, including chronic unpredictable mild stress (CUMS), and chronic social defeat stress (CSDS), to complementarily recapitulate depression-like behaviors. Then, hippocampal tissues were used to detect inflammation-related molecules and signaling pathways. Pathological changes in depressive mouse hippocampal astrocytes were examined by RNA sequencing. After confirming the dopamine receptor 2 (Drd2)/ß-arrestin2 signaling changes in the depressive mice brain, we then established the depressive mouse model using the ß-arrestin2 knockout mice or administrating the ß-arrestin2-biased Drd2 agonist to investigate the roles. Label-free mass spectrometry was used to identify the ß-arrestin2-binding proteins as the underlying mechanisms. We modeled neuroinflammation with interleukin-6 (IL-6) and corticosterone treatment and characterized astrocytes using multiple methods including cell viability assay, flow cytometry, and confocal immunofluorescence. RESULTS: Drd2-biased ß-arrestin2 pathway is significantly changed in the progression of depression, and genetic deletion of ß-arrestin2 aggravates neuroinflammation and depressive-like phenotypes. Mechanistically, astrocytic ß-arrestin2 retains STAT3 in the cytoplasm by structural combination with STAT3, therefore, inhibiting the JAK-STAT3 pathway-mediated inflammatory activation. Furtherly, pharmacological activation of Drd2/ß-arrestin2 pathway by UNC9995 abolishes the inflammation-induced loss of astrocytes and ameliorates depressive-like behaviors in mouse model for depression. CONCLUSIONS: Drd2/ß-arrestin2 pathway is a potential therapeutic target for depression and ß-arrestin2-biased Drd2 agonist UNC9995 is identified as a potential anti-depressant strategy for preventing astrocytic dysfunctions and relieving neuropathological manifestations in mouse model for depression, which provides insights for the therapy of depression.

An oleanolic acid derivative, K73-03, inhibits pancreatic cancer cells proliferation in vitro and in vivo via blocking EGFR/Akt pathway.

Oleanolic acid (OA) and its derivatives show potent anticancer function. Pancreatic cancer (PC) is the fourth core motive of cancer-related deaths worldwide. Epidermal growth factor receptor (EGFR) has been implicated in PC and has been validated as a therapeutic target. Our study demonstrated that K73-03, an OA derivative, was identified as a potent inhibitor of EGFR by using reverse pharmacophore screening and molecular dynamics simulation assays. Moreover, Western blot analysis showed that K73-03 markedly suppressed the levels of phosphorylated-EGFR (p-EGFR) and phosphorylated-Akt (p-Akt). The inhibitory effect of K73-03 on PC cells was assessed in vitro and in vivo. Mechanistically, K73-03 effectively inhibited the cell proliferation of PC cells, and induced apoptosis and autophagy of ASPC-1 cells in a dose-dependent manner. Additionally, pretreatment with chloroquine, an autophagy inhibitor, significantly inhibited K73-03-induced autophagy and enhanced K73-03-induced apoptotic cell death. K73-03 also strongly repressed ASPC-1 cells xenograft growth in vivo. Thus, all these findings provided new clues about OA analog K73-03 as an effective anticancer agent targeted EGFR against ASPC-1 cells, it is worth further evaluation in the future.

Ubiquitin-specific protease 22 ameliorates chronic alcohol-associated liver disease by regulating BRD4.

Alcohol-associated liver disease (ALD) is a liver system disease caused by alcohol abuse, and it involves complex processes ranging from steatosis to fibrosis, cirrhosis and hepatocellular carcinoma. Steatosis and inflammation are the main phenomena involved in ALD. Ubiquitin-specific protease 22 (USP22) plays an important role in liver steatosis; however, its functional contribution to ALD remains unclear. USP22-silenced mice were fed a Lieber-DeCarli liquid diet. AML-12 and HEK293T cells were used to detect the interaction between USP22 and BRD4. Here, we report that hepatic USP22 expression was dramatically upregulated in mice with ALD. Inflammation and steatosis were significantly ameliorated following USP22 silencing in vivo, as indicated by decreased IL-6 and IL-1ß levels. We further showed that the overexpression of USP22 increased inflammation, while knocking down BRD4 suppressed the inflammatory response in AML-12 cells. Notably, USP22 functioned as a BRD4 deubiquitinase to facilitate BRD4 inflammatory functions. More importantly, the expression levels of USP22 and BRD4 in patients with ALD were significantly increased. In conclusion, USP22 acts a key pathogenic factor in ALD by deubiquitinating BRD4, which facilitates the inflammatory response and aggravates ALD.

NLRP3 Inflammasome Inhibition Prevents α-Synuclein Pathology by Relieving Autophagy Dysfunction in Chronic MPTP-Treated NLRP3 Knockout Mice.

Recent researches showed that nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome inhibition exerted dopaminergic neuroprotection in cellular or animal models of Parkinson's disease (PD). NLRP3 inflammasome has been proposed as a drug target for treatment of PD. However, the interplay between chronic NLRP3 inflammasome and progressive α-synuclein pathology keeps poorly understood. Moreover, the potential mechanism keeps unknown. In the present study, we investigate whether NLRP3 inflammasome inhibition prevents α-synuclein pathology by relieving autophagy dysfunction in the chronic 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) mouse model of PD. NLRP3 knockout mice and their wild-type counterparts were treated with continuous MPTP administration via osmotic mini-pumps. Dopaminergic neuronal degeneration was assessed by western blotting and immunohistochemistry (IHC). The levels of dopamine and its metabolites were determined using high-performance liquid chromatography. NLRP3 inflammasome activation and autophagy biomarkers were assessed by western blot. The expressions of pro-inflammatory cytokines were measured by ELISA. The glial reaction and α-synuclein pathology were assessed by IHC and immunofluorescence. Our results show that NLRP3 inflammasome inhibition via NLRP3 knockout not only protects against nigral dopaminergic degeneration and striatal dopamine deletion but also prevents nigral pathological α-synuclein formation in PD mice. Furthermore, it significantly suppresses MPTP-induced glial reaction accompanied by the secretion of pro-inflammatory cytokines in the midbrain of mice. Most importantly, it relieves autophagy dysfunction in the midbrain of PD mice. Collectively, we demonstrate for the first time that improving autophagy function is involved in the preventive effect of NLRP3 inflammasome inhibition on α-synuclein pathology in PD.

Antioxidant and anti-inflammatory effects of dexrazoxane on dopaminergic neuron degeneration in rodent models of Parkinson's disease.

Emerging evidence has demonstrated that the integrity and the function of blood-brain barrier (BBB) are gradually impaired in the processes of aging and nervous system disorders, including neurodegenerative diseases (e.g. Parkinson's disease, PD). The leakage of BBB contributes to the infiltration of peripheral immune cells and harmful mediators into brain parenchyma, even the drugs that can not cross BBB under physiological conditions. Therefore, PD has been regarded as not only a neurodegenerative disease, but also a systemic disorder. In the present study, we demonstrate for the first time that Dexrazoxane (Dex), a drug clinically used to reduce doxorubicin-induced cardiotoxicity in chemotherapy, can enter into midbrain and striatum through broken BBB in 6-hydroxydopamine (6-OHDA)- and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced rodent models of PD. Unexpectedly, Dex (1.5, 5, 15 mg/kg, i.p.) administration for 3-week significantly ameliorates apomorphine-induced contralateral rotation behavior in 6-OHDA-treated rats and Dex (10 mg/kg, i.p.) treatment for 5-week improves MPTP-induced mouse motor dysfunctions. We find that Dex administration protects dopaminergic neurons against neurotoxin-induced degeneration in SNc, accompanied by the attenuated glial cell activation. Further study indicates that suppression of oxidative stress and endoplasmic reticulum stress, as well as the inhibition of systemic inflammation in both peripheral tissues and brain, contribute to the neuroprotective effects of Dex in PD models. Our study implies that Dex may serve as an effective neuroprotectant to treat neurodegeneration and has potential clinical value in term of PD therapeutics.

The effect of fluoxetine on astrocyte autophagy flux and injured mitochondria clearance in a mouse model of depression.

Although multiple hypotheses had been proposed to clarify the causes of depression, the accurate pathogenesis and effective treatment of depression still need to be solved. Pathological change of astrocytes has been recognized to play a pivotal role in depression. Fluoxetine is the first selective serotonin reuptake inhibitor, however, the underlying mechanisms of fluoxetine are incompletely excavated. Emerging evidence shows that fluoxetine promotes autophagic processes in tumor cells. However, whether astrocytic autophagy gets involved in the cytoprotection of fluoxetine on astrocytes in depression treatment remains unexplored. Here we prepared chronic mild stress (CMS)-induced mouse model and treated mice with fluoxetine (10 mg/kg) for 4 weeks to determine the correlation between proautophagic effect of fluoxetine and astrocyte protection in depression. Primary hippocampal astrocytes were cultured to investigate the potential mechanism of fluoxetine in regulating astrocyte autophagy. We found that fluoxetine (10 mg/kg) treatment promoted autophagosome formation and increased clearance of injured mitochondria, consequently protected astrocytes in CMS model mice. Fluoxetine (10 µM) could also promote the autophagic flux unblocked via enhancing fusion of autophagosomes with lysosomes in primary astrocytes. Moreover, fluoxetine promoted mitophagy by increased colocalization of autophagosomes and mitochondria, eliminating damaged mitochondria in corticosterone-treated astrocytes. Further in vitro study showed that p53 presence is required for fluoxetine activated autophagy flux and fluoxetine promotes astrocytic autophagy in a p53-dependent mechanism. Collectively, this work gives us insights into a novel approach to treat depression depending on astrocytes, and provides a promising molecular target for the development of antidepressant drugs besides regulating neurotransmitters.

Design, synthesis, and docking studies of quinazoline analogues bearing aryl semicarbazone scaffolds as potent EGFR inhibitors.

Two series of quinazoline derivatives bearing aryl semicarbazone scaffolds (9a-o and 10a-o) were designed, synthesized and evaluated for the IC50 values against four cancer cell lines (A549, HepG2, MCF-7 and PC-3). The selected compound 9o was further evaluated for the inhibitory activity against EGFR kinases. Four of the compounds showed excellent cytotoxicity activity and selectivity with the IC50 values in single-digit µM to nanomole range. Two of them are equal to more active than positive control afatinib against one or more cell lines. The most promising compound 9o showed the best activity against A549, HepG2, MCF-7 and PC-3 cancer cell lines and EGFR kinase, with the IC50 values of 1.32±0.38µM, 0.07±0.01µM, 0.91±0.29µM and 4.89±0.69µM, which were equal to more active than afatinib (1.40±0.83µM, 1.33±1.28µM, 2.63±1.06µM and 3.96±0.59µM), respectively. Activity of the most promising compound 9o (IC50 56nM) against EGFR kinase was slightly lower to the positive compound afatinib (IC50 1.6nM) but more active than reference staurosporine (IC50 238nM). The result of flow cytometry, with the dose of compound 9o increasing, which indicated the compound 9o could induce remarkable apoptosis of A549 and cells in a dose dependent manner. Structure-activity relationships (SARs) and docking studies indicated that replacement of the cinnamamide group by aryl semicarbazone scaffolds slightly decreased the anti-tumor activity. The results suggested that hydroxy substitution at C-4 had a significant impact on the activity and replacement of the tetrahydrofuran group by methyl moiety was not beneficial for the activity.