Publications by authors named "Xiaoyun Ji"

41 Publications

Structural basis for GTP-induced dimerization and antiviral function of guanylate-binding proteins.

Proc Natl Acad Sci U S A 2021 Apr;118(15)

School of Life Sciences, Tianjin University, Tianjin, 300072, China;

Guanylate-binding proteins (GBPs) form a family of dynamin-related large GTPases which mediate important innate immune functions. They were proposed to form oligomers upon GTP binding/hydrolysis, but the molecular mechanisms remain elusive. Here, we present crystal structures of C-terminally truncated human GBP5 (hGBP5), comprising the large GTPase (LG) and middle (MD) domains, in both its nucleotide-free monomeric and nucleotide-bound dimeric states, together with nucleotide-free full-length human GBP2. Upon GTP-loading, hGBP5 forms a closed face-to-face dimer. The MD of hGBP5 undergoes a drastic movement relative to its LG domain and forms extensive interactions with the LG domain and MD of the pairing molecule. Disrupting the MD interface (for hGBP5) or mutating the hinge region (for hGBP2/5) impairs their ability to inhibit HIV-1. Our results point to a GTP-induced dimerization mode that is likely conserved among all GBP members and provide insights into the molecular determinants of their antiviral function.
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http://dx.doi.org/10.1073/pnas.2022269118DOI Listing
April 2021

Molecular mechanism of RNase R substrate sensitivity for RNA ribose methylation.

Nucleic Acids Res 2021 May;49(8):4738-4749

The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.

RNA 2'-O-methylation is widely distributed and plays important roles in various cellular processes. Mycoplasma genitalium RNase R (MgR), a prokaryotic member of the RNase II/RNB family, is a 3'-5' exoribonuclease and is particularly sensitive to RNA 2'-O-methylation. However, how RNase R interacts with various RNA species and exhibits remarkable sensitivity to substrate 2'-O-methyl modifications remains elusive. Here we report high-resolution crystal structures of MgR in apo form and in complex with various RNA substrates. The structural data together with extensive biochemical analysis quantitively illustrate MgR's ribonuclease activity and significant sensitivity to RNA 2'-O-methylation. Comparison to its related homologs reveals an exquisite mechanism for the recognition and degradation of RNA substrates. Through structural and mutagenesis studies, we identified proline 277 to be responsible for the significant sensitivity of MgR to RNA 2'-O-methylation within the RNase II/RNB family. We also generated several MgR variants with modulated activities. Our work provides a mechanistic understanding of MgR activity that can be harnessed as a powerful RNA analytical tool that will open up a new venue for RNA 2'-O-methylations research in biological and clinical samples.
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http://dx.doi.org/10.1093/nar/gkab202DOI Listing
May 2021

Challenges in adeno-associated virus-based treatment of central nervous system diseases through systemic injection.

Life Sci 2021 Apr 30;270:119142. Epub 2021 Jan 30.

Department of Immunology, Jiangsu University, Zhenjiang 212013, China. Electronic address:

Adeno-associated virus (AAV) vector, an excellent gene therapy vector, has been widely used in the treatment of various central nervous system (CNS) diseases. Due to the presence of the blood-brain barrier (BBB), early attempts at AAV-based CNS diseases treatment were mainly performed through intracranial injections. Subsequently, systemic injections of AAV9, the first AAV that was shown to have BBB-crossing ability in newborn and adult mice, were assessed in clinical trials for multiple CNS diseases. However, the development of systemic AAV injections to treat CNS diseases is still associated with many challenges, such as the efficiency of AAV in crossing the BBB, the peripheral toxicity caused by the expression of AAV-delivered genes, and the immune barrier against AAV in the blood. In this review, we will introduce the biology of the AAV vector and the advantages of systemic AAV injections to treat CNS diseases. Most importantly, we will introduce the challenges associated with systemic injection of therapeutic AAV in treating CNS diseases and suggest feasible solutions.
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http://dx.doi.org/10.1016/j.lfs.2021.119142DOI Listing
April 2021

ILC2-derived IL-9 inhibits colorectal cancer progression by activating CD8 T cells.

Cancer Lett 2021 Apr 9;502:34-43. Epub 2021 Jan 9.

The Central Laboratory, The Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, 212001, China; Department of Immunology, Jiangsu University, Zhenjiang, 212013, China. Electronic address:

Group 2 innate lymphoid cells (ILC2s), characterized by secretion of type 2 cytokines, regulate multiple immune responses. ILC2s are found in different tumor tissues, and ILC2-derived interleukin (IL)-4, IL-5, and IL-13 act on the cells in tumor microenvironment to participate in tumor progression. ILC2s are abundant in colorectal cancer (CRC) tissue, but the role of ILC2s in CRC remains unclear. In this study, we found that the percentage of ILC2s was higher in CRC tissue than in the adjacent normal tissue and that these ILC2s were the dominant IL-9-secreting cell-subsets in CRC tissue, as shown by flow cytometry analysis. ILC2s-derived IL-9 could activate CD8 T cells to inhibit tumor growth, while anti-IL-9 reversed this effect. In vivo experiments showed that neutralizing ILC2s promoted tumor growth, while tumor inhibition occurred by intravenous injection of IL-9. In conclusion, our results demonstrated that ILC2-derived IL-9 could activate CD8 T cells to promote anti-tumor effects in CRC.
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http://dx.doi.org/10.1016/j.canlet.2021.01.002DOI Listing
April 2021

Different T-cell subsets in glioblastoma multiforme and targeted immunotherapy.

Cancer Lett 2021 01 3;496:134-143. Epub 2020 Oct 3.

Department of Immunology, Jiangsu University, Zhenjiang, 212013, China; Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA. Electronic address:

Glioblastoma multiforme (GBM) is a brain tumor with a high mortality rate. Surgical resection combined with radiotherapy and chemotherapy is the standard treatment for GBM patients, but the 5-year survival rate of patients despite this treatment is low. Immunotherapy has attracted increasing attention in recent years. As the pioneer and the main effector cells of immunotherapy, T cells play a key role in tumor immunotherapy. However, the T cells in GBM microenvironment are inhibited by the highly immunosuppressive environment of GBM, posing huge challenges to T cell-based GBM immunotherapy. This review summarizes the effects of the GBM microenvironment on the infiltration and function of different T-cell subsets and the possible strategies to overcome immunosuppression, and thus enhance the effectiveness of GBM immunotherapy.
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http://dx.doi.org/10.1016/j.canlet.2020.09.028DOI Listing
January 2021

IL-9 and IL-9-producing cells in tumor immunity.

Cell Commun Signal 2020 03 30;18(1):50. Epub 2020 Mar 30.

Department of Immunology, Jiangsu University, Zhenjiang, 212013, China.

Interleukin (IL)-9 belongs to the IL-2Rγc chain family and is a multifunctional cytokine that can regulate the function of many kinds of cells. It was originally identified as a growth factor of T cells and mast cells. In previous studies, IL-9 was mainly involved in the development of allergic diseases, autoimmune diseases and parasite infections. Recently, IL-9, as a double-edged sword in the development of cancers, has attracted extensive attention. Since T-helper 9 (Th9) cell-derived IL-9 was verified to play a powerful antitumor role in solid tumors, an increasing number of researchers have started to pay attention to the role of IL-9-skewed CD8 T (Tc9) cells, mast cells and Vδ2 T cell-derived IL-9 in tumor immunity. Here, we review recent studies on IL-9 and several kinds of IL-9-producing cells in tumor immunity to provide useful insight into tumorigenesis and treatment. Video Abstract.
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http://dx.doi.org/10.1186/s12964-020-00538-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7104514PMC
March 2020

HMGB1-induced ILC2s activate dendritic cells by producing IL-9 in asthmatic mouse model.

Cell Immunol 2020 06 6;352:104085. Epub 2020 Mar 6.

Department of Immunology, Jiangsu University, Zhenjiang 212013, China. Electronic address:

Asthma is a disease of the respiratory system that is commonly considered a T-helper 2 (Th2) cell-associated inflammatory disease. Group 2 innate lymphoid cells (ILC2s) promote the inflammatory responses in asthma by secreting type 2 cytokines. Interleukin (IL)-9 also serves as a promoting factor in asthma and it is well known that ILC2s have an autocrine effect of IL-9 to sustain their survival and proliferation. However, the specific role of ILC2-derived IL-9 in asthma remains unclear. HMGB1 (High-Mobility Group Box-1) is a nuclear protein, and Previous studies have shown that HMGB1 can regulate the differentiation of T-helper cells and participate in the development of asthma. But whether HMGB1 can regulate the innate lymphocytes in the pathological process of asthma is unknown. In this study we have shown increased presence of HMGB1 protein in the lung of mice with asthma, which was associated with increased secretion of IL-9 by ILC2s. This led to the activation of dendritic cells (DCs) that can accelerate the differentiation of Th2 cells and worsen the severity of asthma. Taken together, our study provides a complementary understanding of the asthma development and highlights a novel inflammatory pathway in the pathogenesis of asthma.
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http://dx.doi.org/10.1016/j.cellimm.2020.104085DOI Listing
June 2020

Pioglitazone for the Primary and Secondary Prevention of Cardiovascular and Renal Outcomes in Patients with or at High Risk of Type 2 Diabetes Mellitus: A Meta-Analysis.

J Clin Endocrinol Metab 2020 05;105(5)

Department of Endocrinology, Affiliated Hospital of Medical College Qingdao University, Qingdao, China.

Context: The goal of the meta-analysis was to evaluate the effect of pioglitazone on the primary and secondary prevention of cardiovascular diseases (CVDs) and renal adverse events in patients with or at high risk of type 2 diabetes mellitus (T2DM).

Design: Randomized controlled trials (RCTs) comparing pioglitazone with any control were identified through PubMed, Embase, and the Cochrane Library. Cardiovascular outcomes included major adverse cardiovascular events (MACEs, defined as the composite of nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death), hospitalization for heart failure, and all-cause mortality. Renal outcomes included change in urinary albumin to creatinine ratio and 24-hour urinary protein excretion. Weighted mean difference (WMD) and risk ratio (RR) with 95% confidence intervals (CIs) were pooled.

Results: A total of 26 studies with 19 645 participants were enrolled. Pioglitazone reduced the risk of MACE (RR, 0.8 [95% CI, 0.7-0.9]), with benefit only seen in patients with a history of established CVDs (0.8 [0.7-0.9]) and not in those without (1.0 [0.7-1.3]). Regarding the individual components, pioglitazone reduced the risk of nonfatal myocardial infarction (0.8 [0.6-1.0]) and nonfatal stroke (0.8 [0.7-0.9]), which was confined to patients with a history of established CVDs, whereas no treatment effect was found on cardiovascular death (1.0 [0.7-1.2]) regardless of the presence of established CVDs. Pioglitazone increased the risk of hospitalization for heart failure (1.3 [1.1-1.6]) and had no treatment effect on all-cause mortality (1.0 [0.8-1.1]). Pioglitazone reduced albuminuria by 18.5% (WMD 18.5% [95% CI, 21.1-16.0]), with a similar benefit in patients with different renal function categories.

Conclusions: Pioglitazone should be considered in patients with or at high risk of T2DM for the prevention of cardiovascular endpoints, especially in those with a history of established CVD who might benefit the most. Robust reductions in progression of renal disease are seen regardless of baseline renal function degree.
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http://dx.doi.org/10.1210/clinem/dgz252DOI Listing
May 2020

Low frequency of IL-10-producing B cells and high density of ILC2s contribute to the pathological process in Graves' disease, which may be related to elevated-TRAb levels.

Autoimmunity 2020 03 6;53(2):78-85. Epub 2019 Dec 6.

International Genomics Research Center (IGRC), Jiangsu University, Zhenjiang, China.

IL-10-producing B Cells (B10) is a functionally defined regulatory Bcell subset. It plays an important role in the control of inflammation and autoimmune diseases, although it is present at low numbers in peripheral blood. Graves' disease is an autoimmune disease characterized by the production of autoantibodies such as TRAb. ILC2s maintains Th2 polarization state by producing typeII cytokines. It is not clear whether the level of autoantibody is related to ILC2s and B10 cells in Graves' disease. In this study, we analyzed the frequencies of B10, Treg cells and ILC2s, as well as the expression of related cytokines in peripheral blood from patients with Graves' disease and evaluated the correlation between B10 cell numbers and autoantibodies level. Our data showed that the frequency of B10 or Treg cells was significantly decreased in peripheral blood mononuclear cells from Graves' disease patients, while the percentage of ILC2s cells was increased; the levels of cytokine IL-5, IL-13 and related transcription factor RORα were up-regulated. Autoantibodies analysis also showed that high level of TRAb was accompanied by low rates of B10 cells in patients, there was a negative correlation trend. In addition, the analytical data from mouse disease models also showed similar results. It indicates that B10 cells may affect the production of TRAb by negative regulation of Th2 cells, while ILC2s can promote the production of autoantibodies such as TRAb by maintaining the dominant response state of Th2 cells.
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http://dx.doi.org/10.1080/08916934.2019.1698553DOI Listing
March 2020

Evaluation of Peripheral Immune Dysregulation in Alzheimer's Disease and Vascular Dementia.

J Alzheimers Dis 2019 ;71(4):1175-1186

CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.

Immune dysregulation has been observed in the brain and blood of patients with Alzheimer's disease (AD). However, a convenient assay to evaluate peripheral immune dysregulation in AD has not been developed, partly due to the inconsistent observations from different studies. We hypothesized that peripheral immune dysregulation may only exist in a subpopulation of AD patients; therefore it may be valuable to identify this subpopulation with a convenient assay. Along this line, we selected 14 candidate genes based on our analysis of microarray data on peripheral blood of AD and other diseases. We used RT-qPCR to examine the expression of these 14 genes in a cohort of 288 subjects, including 74 patients with AD, 64 patients with mild cognitive impairment (MCI), 51 patients with vascular dementia (VaD), and 99 elderly controls with no cognitive dysfunction/impairment. Seven of these 14 genes displayed significant difference in group comparison. Switching from group comparison to individualized evaluation revealed more in-depth information. First, there existed a wide dynamic range for the expression of these immune genes in peripheral blood even within the control group. Second, for the vast majority of the patients (AD, VaD, and MCI patients), the expression of these genes fell within the dynamic range of the control group. Third, a small portion of outliers were observed in the patient groups, more so in the VaD group than that in the AD or MCI groups. This is our first attempt to conduct personalized evaluation of peripheral immune dysregulation in AD and VaD. These findings may be applicable to the identification of peripheral immune dysregulation in AD and VaD patients which may lead to tailored treatment toward those patients.
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http://dx.doi.org/10.3233/JAD-190666DOI Listing
November 2020

Inhibition of NLRP3 inflammasome-mediated pyroptosis in macrophage by cycloastragenol contributes to amelioration of imiquimod-induced psoriasis-like skin inflammation in mice.

Int Immunopharmacol 2019 Sep 13;74:105682. Epub 2019 Jun 13.

State Key Laboratory of Pharmaceutical Biotechnology, Department of Biotechnology and Pharmaceutical Sciences, School of Life Sciences, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China. Electronic address:

Psoriasis is a common chronic inflammatory skin disease, and the infiltrated macrophages in psoriatic skin lesions play a key role in the progression of this uncontrolled cutaneous inflammation. However, the current therapeutic strategies for patients with psoriasis are not satisfactory. Here, we report that cycloastragenol (CAG), a natural active small compound isolated from Astragalus membranaceus, significantly ameliorated imiquimod (IMQ)-induced psoriasiform dermatitis in mice by targeting proinflammatory macrophages. CAG significantly reduced the clinical scores, decreased the epidermal thickness, and ameliorated the deteriorating histopathology observed in IMQ-induced mice. CAG treatment specifically reduced the dermal infiltration of macrophages, rather than of dendritic cells, neutrophils, or T lymphocytes, into psoriatic skin. CAG dose-dependently decreased the level of proinflammatory cytokines, including IL-1β, TNF-α and IL-6, in murine psoriatic skin and serum, as well as in IMQ-stimulated, bone-marrow-derived macrophages. When compared to the control group, CAG significantly decreased IMQ-triggered NLRP3 inflammasome activation and gasdermin D-mediated cell pyroptosis in these proinflammatory macrophages. CAG also suppressed the assembly of the NLRP3 inflammasome complex. Taken together, the results show that CAG selectively modulates macrophage function by inhibiting NLRP3 inflammasome-mediated pyroptosis to ameliorate IMQ-induced psoriasis-like skin inflammation in mice. Our findings also identify an effective drug candidate for the treatment of psoriasis.
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http://dx.doi.org/10.1016/j.intimp.2019.105682DOI Listing
September 2019

The structural basis for cancer drug interactions with the catalytic and allosteric sites of SAMHD1.

Proc Natl Acad Sci U S A 2018 10 10;115(43):E10022-E10031. Epub 2018 Oct 10.

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520;

SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that depletes cellular dNTPs in noncycling cells to promote genome stability and to inhibit retroviral and herpes viral replication. In addition to being substrates, cellular nucleotides also allosterically regulate SAMHD1 activity. Recently, it was shown that high expression levels of SAMHD1 are also correlated with significantly worse patient responses to nucleotide analog drugs important for treating a variety of cancers, including acute myeloid leukemia (AML). In this study, we used biochemical, structural, and cellular methods to examine the interactions of various cancer drugs with SAMHD1. We found that both the catalytic and the allosteric sites of SAMHD1 are sensitive to sugar modifications of the nucleotide analogs, with the allosteric site being significantly more restrictive. We crystallized cladribine-TP, clofarabine-TP, fludarabine-TP, vidarabine-TP, cytarabine-TP, and gemcitabine-TP in the catalytic pocket of SAMHD1. We found that all of these drugs are substrates of SAMHD1 and that the efficacy of most of these drugs is affected by SAMHD1 activity. Of the nucleotide analogs tested, only cladribine-TP with a deoxyribose sugar efficiently induced the catalytically active SAMHD1 tetramer. Together, these results establish a detailed framework for understanding the substrate specificity and allosteric activation of SAMHD1 with regard to nucleotide analogs, which can be used to improve current cancer and antiviral therapies.
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http://dx.doi.org/10.1073/pnas.1805593115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6205433PMC
October 2018

Mechanism of ATP hydrolysis by the Zika virus helicase.

FASEB J 2018 10 17;32(10):5250-5257. Epub 2018 Apr 17.

School of Life Sciences, Tianjin University, Tianjin, China.

During its life cycle, Zika virus (ZIKV), an arthropod-borne flavivirus that is associated with Guillain-Barré syndrome and causes microencephaly in fetuses and newborn children, encodes a critical and indispensable helicase domain that has 5'-triphosphatase activity and performs ATP hydrolysis to generate energy and thus, sustains unwinding of double-stranded RNA during ZIKV genome replication. Of these processes, ATP hydrolysis represents the most basic event; however, its dynamic mechanisms remain largely unknown, impeding the further understanding of the function of ZIKV helicase and the ongoing anti-ZIKV drug design. In this work, we determined the crystal structure of ZIKV helicase in complex with ADP-AlF-Mn and ADP-Mn separately. The structural analysis indicates that these structures represent the intermediate state and posthydrolysis state, respectively, of the ATP hydrolysis process of ZIKV helicase. These findings, together with our earlier work, which identified the prehydrolysis state of ZIKV helicase, lead to a proposal of the ATP hydrolysis cycle for ZIKV helicase. On this basis, we used site-directed mutagenesis combined with an enzymatic study to identify successfully residues that are critical for the ATPase activity of ZIKV helicase; this will provide new ideas to understand the function for the key enzyme of ZIKV.-Yang, X., Chen, C., Tian, H., Chi, H., Mu, Z., Zhang, T., Yang, K., Zhao, Q., Liu, X., Wang, Z., Ji, X., Yang, H. Mechanism of ATP hydrolysis by the Zika virus helicase.
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http://dx.doi.org/10.1096/fj.201701140RDOI Listing
October 2018

HMGB1 silencing in macrophages prevented their functional skewing and ameliorated EAM development: Nuclear HMGB1 may be a checkpoint molecule of macrophage reprogramming.

Int Immunopharmacol 2018 Mar 2;56:277-284. Epub 2018 Feb 2.

Department of Immunology, Jiangsu University, Zhenjiang 212013, China. Electronic address:

High-mobility group box 1 (HMGB1), an important inflammatory factor, plays significant roles in CD4T cell differentiation, cancer and autoimmune disease development. Our previous data have demonstrated that HMGB1 contributes to macrophage reprogramming and is involved in experimental autoimmune myocarditis (EAM) development. In contrast to the well-explored function of HMGB1, little is known about the nuclear function. Whether HMGB1 can serve as an architectural factor and control functional skewing of macrophages remains unclear. Therefore, the present work was performed to address the above speculation. The adenovirus-mediated shRNA (Ad-shRNA) was employed to knock down HMGB1 in RAW264.7 and monocytes/macrophages of EAM mice. Our data showed that in vitro HMGB1 silencing limited functional skewing of macrophages and down-regulated inflammatory factors secretion, which can't be reversed by the exogenous HMGB1. In M1 polarization system, the phosphorylations of NF-κB, p38 and Erk1/2 were inhibited following HMGB1 silencing. In vivo, HMGB1 silencing could effectively ameliorate EAM development. Our data suggest that HMGB1 may be a checkpoint nuclear factor of macrophage reprogramming. Our findings also provide an exciting therapeutic method for inflammatory disorders.
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http://dx.doi.org/10.1016/j.intimp.2018.01.013DOI Listing
March 2018

The SAM domain of mouse SAMHD1 is critical for its activation and regulation.

Nat Commun 2018 01 29;9(1):411. Epub 2018 Jan 29.

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.

Human SAMHD1 (hSAMHD1) is a retroviral restriction factor that blocks HIV-1 infection by depleting the cellular nucleotides required for viral reverse transcription. SAMHD1 is allosterically activated by nucleotides that induce assembly of the active tetramer. Although the catalytic core of hSAMHD1 has been studied extensively, previous structures have not captured the regulatory SAM domain. Here we report the crystal structure of full-length SAMHD1 by capturing mouse SAMHD1 (mSAMHD1) structures in three different nucleotide bound states. Although mSAMHD1 and hSAMHD1 are highly similar in sequence and function, we find that mSAMHD1 possesses a more complex nucleotide-induced activation process, highlighting the regulatory role of the SAM domain. Our results provide insights into the regulation of SAMHD1 activity, thereby facilitating the improvement of HIV mouse models and the development of new therapies for certain cancers and autoimmune diseases.
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http://dx.doi.org/10.1038/s41467-017-02783-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5788916PMC
January 2018

Ebselen: Mechanisms of Glutamate Dehydrogenase and Glutaminase Enzyme Inhibition.

ACS Chem Biol 2017 12 7;12(12):3003-3011. Epub 2017 Nov 7.

College of Pharmaceutical Science, Collaborative Innovation Center of Yangtza River Delta Region Green Pharmaceuticals, Zhejiang University of Technology , Hangzhou, China.

Ebselen modulates target proteins through redox reactions with selenocysteine/cysteine residues, or through binding to the zinc finger domains. However, a recent contradiction in ebselen inhibition of kidney type glutaminase (KGA) stimulated our interest in investigating its inhibition mechanism with glutamate dehydrogenase (GDH), KGA, thioredoxin reductase (TrxR), and glutathione S-transferase. Fluorescein- or biotin-labeled ebselen derivatives were synthesized for mechanistic analyses. Biomolecular interaction analyses showed that only GDH, KGA, and TrxR proteins can bind to the ebselen derivative, and the binding to GDH and KGA could be competed off by glutamine or glutamate. From the gel shift assays, the fluorescein-labeled ebselen derivative could co-migrate with hexameric GDH and monomeric/dimeric TrxR in a dose-dependent manner; it also co-migrated with KGA but disrupted the tetrameric form of the KGA enzyme at a high compound concentration. Further proteomic analysis demonstrated that the ebselen derivative could cross-link with proteins through a specific cysteine at the active site of GDH and TrxR proteins, but for KGA protein, the binding site is at the N-terminal appendix domain outside of the catalytic domain, which might explain why ebselen is not a potent KGA enzyme inhibitor in functional assays. In conclusion, ebselen could inhibit enzyme activity by binding to the catalytic domain or disruption of the protein complex. In addition, ebselen is a relatively potent selective GDH inhibitor that might provide potential therapeutic opportunities for hyperinsulinism-hyperammonemia syndrome patients who have the mutational loss of GTP inhibition.
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http://dx.doi.org/10.1021/acschembio.7b00728DOI Listing
December 2017

A Mutation Identified in Neonatal Microcephaly Destabilizes Zika Virus NS1 Assembly in Vitro.

Sci Rep 2017 02 15;7:42580. Epub 2017 Feb 15.

School of Life Sciences, Tianjin University, Tianjin 300072, People's Republic of China.

An unprecedented epidemic of Zika virus (ZIKV) infection had spread to South and Central America. ZIKV infection was recently confirmed by CDC (the Centers for Disease Control and Prevention) to cause neonatal microcephaly, which posed a significant public health emergency of international concern. No specific vaccines or drugs are currently available to fight ZIKV infection. ZIKV nonstructural protein 1 (NS1) plays an essential role in viral replication and immune evasion. We determined the crystal structure of ZIKV NS1, which forms a head-to-head, symmetric dimer with a unique 14-stranded β-ladder conserved among flaviviruses. The assembly of the β-ladder dimer is concentration dependent. Strikingly, one pathogenic mutation T233A (NCBI accession no. KU527068), found in the brain tissue of infected fetus with neonatal microcephaly, is located at the dimer interface. Thr233, a unique residue found in ZIKV but not in other flaviviruses, organizes a central hydrogen bonding network at NS1 dimer interface. Mutation of Thr233 to Ala disrupts this elaborated interaction network, and destabilizes the NS1 dimeric assembly in vitro. In addition, our structural comparison of epitopes for protective antibody 22NS1, targeting West Nile Virus NS1, could potentially be valuable in understanding its anti-virus specificities and in the development of antibodies against ZIKV.
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http://dx.doi.org/10.1038/srep42580DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5309781PMC
February 2017

IL-17B activated mesenchymal stem cells enhance proliferation and migration of gastric cancer cells.

Oncotarget 2017 Mar;8(12):18914-18923

Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, China.

Mesenchymal stem cells are important cells in tumor microenvironment. We have previously demonstrated that IL-17B/IL-17RB signal promoted progression of gastric cancer. In this study, we further explored the effect of IL-17B on mesenchymal stem cells in tumor microenvironment and its impact on the tumor progression. The results showed that IL-17B induced the expression of stemness-related genes Nanog, Sox2, and Oct4 in mesenchymal stem cells and enhanced its tumor-promoting effect. The supernatant from cultured mesenchymal stem cells after treating with exogenous rIL-17B promoted the proliferation and migration of MGC-803, therefor suggesting that rIL-17B might promote mesenchymal stem cells to produce soluble factors. In addition, rIL-17B also activated the NF-κΒ, STAT3, β-catenin pathway in mesenchymal stem cells. Our data revealed a new mechanism that IL-17B enhanced the progression of gastric cancer by activating mesenchymal stem cells.
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http://dx.doi.org/10.18632/oncotarget.14835DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5386657PMC
March 2017

Mechanisms of activation and inhibition of Zika virus NS2B-NS3 protease.

Cell Res 2016 11 18;26(11):1260-1263. Epub 2016 Oct 18.

School of Life Sciences, Tianjin University, Tianjin 300072, China.

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http://dx.doi.org/10.1038/cr.2016.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5099865PMC
November 2016

SAMHD1-mediated HIV-1 restriction in cells does not involve ribonuclease activity.

Nat Med 2016 10;22(10):1072-1074

Center for Retrovirus Research, Department of Veterinary Biosciences, Ohio State University, Columbus, Ohio, USA.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5069697PMC
http://dx.doi.org/10.1038/nm.4163DOI Listing
October 2016

Structural basis of Zika virus helicase in recognizing its substrates.

Protein Cell 2016 08 18;7(8):562-70. Epub 2016 Jul 18.

College of Life Sciences, Nankai University, Tianjin, 300071, China.

The recent explosive outbreak of Zika virus (ZIKV) infection has been reported in South and Central America and the Caribbean. Neonatal microcephaly associated with ZIKV infection has already caused a public health emergency of international concern. No specific vaccines or drugs are currently available to treat ZIKV infection. The ZIKV helicase, which plays a pivotal role in viral RNA replication, is an attractive target for therapy. We determined the crystal structures of ZIKV helicase-ATP-Mn(2+) and ZIKV helicase-RNA. This is the first structure of any flavivirus helicase bound to ATP. Comparisons with related flavivirus helicases have shown that although the critical P-loop in the active site has variable conformations among different species, it adopts an identical mode to recognize ATP/Mn(2+). The structure of ZIKV helicase-RNA has revealed that upon RNA binding, rotations of the motor domains can cause significant conformational changes. Strikingly, although ZIKV and dengue virus (DENV) apo-helicases share conserved residues for RNA binding, their different manners of motor domain rotations result in distinct individual modes for RNA recognition. It suggests that flavivirus helicases could have evolved a conserved engine to convert chemical energy from nucleoside triphosphate to mechanical energy for RNA unwinding, but different motor domain rotations result in variable RNA recognition modes to adapt to individual viral replication.
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http://dx.doi.org/10.1007/s13238-016-0293-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4980333PMC
August 2016

Non-tumor tissue derived interleukin-17B activates IL-17RB/AKT/β-catenin pathway to enhance the stemness of gastric cancer.

Sci Rep 2016 05 5;6:25447. Epub 2016 May 5.

Department of Immunology, School of medicine, Jiangsu University, Zhenjiang, Jiangsu, PR China.

Inflammation is a critical component involved in tumor progression. Interleukin-17 (IL-17) belongs to a relatively new family of cytokines that has been associated with the progression of cancers. However, the role of IL-17B/IL-17RB (IL-17 receptor B) signaling to stemness of gastric cancer remains unknown. Here, we confirmed that the expression of IL-17RB in gastric cancer tissues was significantly increased, that overexpression was associated with poor prognosis of gastric cancer patients, and that overexpression was positively correlated with some stemness markers. Interestingly, the expression of IL-17B was upregulated in patient serum rather than gastric tumor tissues. Furthermore, exogenous rIL-17B significantly promoted the stemness of gastric cancer cells depending on IL-17RB and induced the expression of IL-17RB. Simultaneously, the expression of phosphorylated AKT, GSK-3β, and β-catenin as well as the nuclear translocation of β-catenin were significantly increased in the MGC-803 cell in a dose-dependent manner, when treated with rIL-17B. The AKT inhibitor, LY294002, and the knockdown of AKT expression reversed the rIL-17B-induced upregulation of β-catenin and some stemness markers. Together, our results indicate that the IL-17B/IL-17RB signal can promote the growth and migration of tumor cells, and upregulate cell stemness through activating the AKT/β-catenin pathway in gastric cancer, suggesting that IL-17RB may be a novel target in human gastric cancer therapy.
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http://dx.doi.org/10.1038/srep25447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4857095PMC
May 2016

Aminoguanidine cream ameliorates skin tissue microenvironment in diabetic rats.

Arch Med Sci 2016 Feb 2;12(1):179-87. Epub 2016 Feb 2.

Shanghai Burns Institute, Rui Jin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.

Introduction: The aim of the study was to explore the effect of aminoguanidine cream on the skin tissue microenvironment in diabetic rats.

Material And Methods: A total of 51 healthy male Sprague Dawley (SD) rats were randomly divided into three groups: the diabetes group (n = 18), the aminoguanidine group (n = 18) and the control group (n = 15). Rats in the diabetes group and aminoguanidine group were injected with 65 mg/kg streptozotocin to induce the diabetes model, and in the control group with citrate buffer. After successful induction of diabetes, the back hair of all rats was stripped by barium sulfide, and the aminoguanidine group was treated with aminoguanidine cream using disinfected cotton swabs twice every day for 40 days, while the diabetes and control groups were treated with the cream matrix. The pathological changes of skin were observed by HE staining, while the content of inflammatory cytokines (TNF-α, IL-8, ICAM and IL-1α) and the antioxidant indexes (T-AOC, GSH-PX, MPO MDA H2O2) were examined using commercial kits.

Results: After 40 days of treatment, the diabetes group manifested tissue lesions, whereas the aminoguanidine group seemed normal. Compared with the diabetes group, the content of inflammatory cytokines TNF-α, IL-8, ICAM and IL-1α was dramatically lower in the aminoguanidine group. T-AOC in all groups underwent dramatic changes and returned to normal finally. The activities of GSH-PX and MPO and content of H2O2 in the diabetes group were all higher than those in the aminoguanidine group.

Conclusions: Aminoguanidine may have a good systemic effect on alleviating the pathological changes of skin tissue in diabetic rats, which may be attributed to the regulation of GSH-PX, TNF-α, IL-8, ICAM and IL-1α.
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http://dx.doi.org/10.5114/aoms.2016.57595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4754380PMC
February 2016

[Fibrosis after damage to fat dome structure of skin of pig].

Zhonghua Shao Shang Za Zhi 2015 Oct;31(5):349-53

Shanghai Institute of Burns, Shanghai Research Center of Wound Repair, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China; Email:

Objective: To observe the fibrosis of skin after damage to the fat dome structure in skin of pig.

Methods: Totally 4 pieces of skin grafts of intermediate thickness in the size of 5 cm × 5 cm were obtained from both sides beside the spine of back in each of the 4 female red Duroc pigs with pedicle on one side with Humby knife performed by burn specialists, who were rich in clinical experience. These skin grafts were assigned as thin dermis group (TD). Pedicled tissue grafts in the size of 5 cm × 5 cm with the thickness of 1.5 mm were obtained within the wounds resulted from former incision with the same method mentioned above, and these tissue grafts were set as fat dome group (FD). The above-mentioned two groups of skin grafts were sutured back in situ immediately after completion of the former procedures. On post surgery day (PSD) 7, 14, and 21, 5 wounds were respectively selected according to the random number table for gross observation of the surgical areas. Tissue samples were obtained from corresponding surgical area deep to the deep fascia after gross observation at above-mentioned time points. Some of the tissue samples were used for observation of distribution of collagen fibers in the regions of operation of both groups of skin grafts with HE staining, and the breadth of fibrosis was measured; some of the tissue samples were used for observation of distribution of type I or III collagen fibers in the regions of incision of both two groups of skin grafts with Sirius red staining. Data were processed with two independent sample t test.

Results: A little scab on the edge of wounds was observed on PSD 7; all the wounds were healed on PSD 14; a few hairs were observed growing in the surgical area on PSD 21. HE staining showed that traces of incision were observed in the superficial layer of dermis and at the junction between dermis and fat dome at each time point; profuse hyperplasia of collagen fibers with parallel and orderly arrangement were observed in the region of incision of skin grafts in groups TD and FD at each time point. The breadth of fibrosis of the region of incision of skin grafts was respectively (251 ± 31), (240 ± 3 7), and (342 ± 69) µm in group TD, (239 ± 36), (286 ± 61), and (332 ± 28) µm in group FD on PSD 7, 14, 21, without significantly statistical difference (with t values respectively 0.750, -1.971, and 0.375, P values above 0.05). Sirius red staining showed that large amount of type III collagen fibers and small amount of type I collagen fibers arranging parallelly were present in the region of incision of skin grafts in groups TD and FD at each time point.

Conclusions: Under the circumstances of relatively intact restoration of dermal tissue, no excessive fibrosis was observed after simple incisional injury of fat dome in skin of pig.
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October 2015

Impaired dNTPase activity of SAMHD1 by phosphomimetic mutation of Thr-592.

J Biol Chem 2015 Oct 20;290(44):26352-9. Epub 2015 Aug 20.

From the Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520 and

SAMHD1 is a cellular protein that plays key roles in HIV-1 restriction and regulation of cellular dNTP levels. Mutations in SAMHD1 are also implicated in the pathogenesis of chronic lymphocytic leukemia and Aicardi-Goutières syndrome. The anti-HIV-1 activity of SAMHD1 is negatively modulated by phosphorylation at residue Thr-592. The mechanism underlying the effect of phosphorylation on anti-HIV-1 activity remains unclear. SAMHD1 forms tetramers that possess deoxyribonucleotide triphosphate triphosphohydrolase (dNTPase) activity, which is allosterically controlled by the combined action of GTP and all four dNTPs. Here we demonstrate that the phosphomimetic mutation T592E reduces the stability of the SAMHD1 tetramer and the dNTPase activity of the enzyme. To better understand the underlying mechanisms, we determined the crystal structures of SAMHD1 variants T592E and T592V. Although the neutral substitution T592V does not perturb the structure, the charged T592E induces large conformational changes, likely triggered by electrostatic repulsion from a distinct negatively charged environment surrounding Thr-592. The phosphomimetic mutation results in a significant decrease in the population of active SAMHD1 tetramers, and hence the dNTPase activity is substantially decreased. These results provide a mechanistic understanding of how SAMHD1 phosphorylation at residue Thr-592 may modulate its cellular and antiviral functions.
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http://dx.doi.org/10.1074/jbc.M115.677435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4646291PMC
October 2015

Polyhedra structures and the evolution of the insect viruses.

J Struct Biol 2015 Oct 18;192(1):88-99. Epub 2015 Aug 18.

Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, United Kingdom; Diamond House, Diamond Light Source, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom. Electronic address:

Polyhedra represent an ancient system used by a number of insect viruses to protect virions during long periods of environmental exposure. We present high resolution crystal structures of polyhedra for seven previously uncharacterised types of cypoviruses, four using ab initio selenomethionine phasing (two of these required over 100 selenomethionine crystals each). Approximately 80% of residues are structurally equivalent between all polyhedrins (pairwise rmsd ⩽ 1.5 Å), whilst pairwise sequence identities, based on structural alignment, are as little as 12%. These structures illustrate the effect of 400 million years of evolution on a system where the crystal lattice is the functionally conserved feature in the face of massive sequence variability. The conservation of crystal contacts is maintained across most of the molecular surface, except for a dispensable virus recognition domain. By spreading the contacts over so much of the protein surface the lattice remains robust in the face of many individual changes. Overall these unusual structural constraints seem to have skewed the molecule's evolution so that surface residues are almost as conserved as the internal residues.
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http://dx.doi.org/10.1016/j.jsb.2015.08.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4597613PMC
October 2015

Two tales (tails) of SAMHD1 destruction by Vpx.

Cell Host Microbe 2015 Apr;17(4):425-7

Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA. Electronic address:

The lentivirus protein Vpx/Vpr recognizes the host restriction factor SAMHD1 at either its N- or C-terminal tail and targets it for destruction by the cellular protein degradation machinery. In this issue of Cell Host & Microbe, Schwefel et al. (2015) report the structural basis of SAMHD1 N-terminal targeting by Vpx.
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http://dx.doi.org/10.1016/j.chom.2015.03.013DOI Listing
April 2015

Structure of CPV17 polyhedrin determined by the improved analysis of serial femtosecond crystallographic data.

Nat Commun 2015 Mar 9;6:6435. Epub 2015 Mar 9.

1] Division of Structural Biology, The Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, Oxfordshire OX3 7BN, UK [2] Diamond House, Diamond Light Source, Harwell Science &Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK.

The X-ray free-electron laser (XFEL) allows the analysis of small weakly diffracting protein crystals, but has required very many crystals to obtain good data. Here we use an XFEL to determine the room temperature atomic structure for the smallest cytoplasmic polyhedrosis virus polyhedra yet characterized, which we failed to solve at a synchrotron. These protein microcrystals, roughly a micron across, accrue within infected cells. We use a new physical model for XFEL diffraction, which better estimates the experimental signal, delivering a high-resolution XFEL structure (1.75 Å), using fewer crystals than previously required for this resolution. The crystal lattice and protein core are conserved compared with a polyhedrin with less than 10% sequence identity. We explain how the conserved biological phenotype, the crystal lattice, is maintained in the face of extreme environmental challenge and massive evolutionary divergence. Our improved methods should open up more challenging biological samples to XFEL analysis.
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http://dx.doi.org/10.1038/ncomms7435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4403592PMC
March 2015