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Che Y, Chien Y, Zhu Y, Huang X, Wu L, Ai Y, Jiang S, Li F, Chen S. GSDMD-Dependent Neutrophil Extracellular Traps Mediate Portal Vein Thrombosis and Associated Fibrosis in Cirrhosis. Int J Mol Sci 2024; 25:9099. [PMID: 39201786 PMCID: PMC11354441 DOI: 10.3390/ijms25169099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 08/14/2024] [Accepted: 08/20/2024] [Indexed: 09/03/2024] Open
Abstract
Portal vein thrombosis (PVT) is a challenging and controversial complication of cirrhosis. Experimental models that reproduce cirrhotic PVT and effective pharmacological therapies are limited. We aimed to investigate the nature course and mechanisms of PVT in cirrhosis. A novel PVT model was developed via two-step total portal vein ligation in healthy and thioacetamide (TAA)-cirrhotic rats. Circulating and liver-infiltrating neutrophils were isolated from individuals with cirrhosis to examine neutrophil extracellular traps (NETs) and explore their unique characteristics and implications in PVT-associated fibrosis in cirrhosis. We further validated macrophage-myofibroblast transition (MMT) via multiplex immunofluorescence and single-cell sequencing. In the experimental model, cirrhosis promoted PVT development and portal vein intimal thickening. Interestingly, cirrhosis promoted spontaneous resolution of PVT due to instability of thrombus structure, along with pulmonary and intrahepatic clots. NETs-MMT mediate cirrhotic PVT and PVT-associated fibrosis, including fibrotic thrombus remodeling and increased hepatic collagen deposition. Mechanistically, caspase-4-dependent activation of neutrophils and GSDMD mediated the formation of NETs. The extracellular DNA of NETs promoted TGF-β1/Smad3-driven MMT. Inhibiting GSDMD with disulfiram suppressed cirrhotic PVT and prevented associated fibrosis. The cirrhotic PVT model reflected the following three main characteristics of cirrhotic PVT: spontaneous resolution, immunothrombosis, and intimal fibrosis. Targeting NETs with GSDMD inhibitors may serve as a new therapeutic concept to treat cirrhotic PVT.
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Chien Y, guilleminault C. 0442 ADULT SHORT LINGUAL FRENULUM < AND > OBSTRUCTIVE-SLEEP-APNEA LINGUAL FRENULUM & OBSTRUCTIVE-SLEEP-APNEALINGUAL FRENULUM
& OBSTRUCTIVE-SLEEP-APNEALINGUAL FRENULUM AND OBSTRUCTIVE-SLEEP-APNEA. Sleep 2017. [DOI: 10.1093/sleepj/zsx050.441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ding K, Chien Y, Chien C. Reducing the expression of glutathione transferase D mRNA in Drosophila melanogaster exposed to phenol and aniline. ENVIRONMENTAL TOXICOLOGY 2005; 20:507-12. [PMID: 16161104 DOI: 10.1002/tox.20139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phenol and aniline are toxic to animals. The purpose of the present study was to examine the expression of glutathione transferase D mRNA in fruit flies altered by long-term exposure to phenol and aniline. Changes in the amount of mRNA were measured by a semiquantitative reverse-transcription polymerase chain reaction assay. The level of each glutathione transferase D mRNA expressed in the phenol-treated and aniline-treated strains of adult fruit flies differed after chemical treatment. Aniline was more potent than phenol in suppressing the expression of cytosolic glutathione transferase D mRNA. Aniline reduced the level of glutathione transferase mRNA expressed in the aniline-treated strain to less than a 0.5 fraction as compared to that measured in the wild-type strain. But phenol was only able to suppress the GstD7 and GstD4 mRNAs expressed in the phenol-treated strain. Neither aniline nor phenol reduced the expression of microsomal glutathione transferase mRNA in fruit flies.
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Shen S, Chien Y, Chien C. Induction of glutathione S-transferases activities in Drosophila melanogaster exposed to phenol. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2003; 53:80-91. [PMID: 12761875 DOI: 10.1002/arch.10087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Studying the toxic effects of long-term exposing fruit flies to phenol is the object of this study. The induction of the glutathione S-transferases enzymatic activities, the change in the amount of mRNA related to phenol exposure, the change in survival rate of adult fruit flies, and the chemical interaction between phenol and benzene were the problems to be investigated. Glutathione S-transferases were separated by affinity chromatography and the mRNAs levels were quantified by reverse-transcription polymerase chain reaction. Long-term feeding phenol to wild type fruit flies had caused some toxic effects included increasing the resistance to phenol toxicity, lowering the benzene toxicity, and induction of glutathione S-transferases enzymatic activities. But no significant change in the amount of glutathione S-transferases GstD1 and GstD5 mRNAs had occurred. From these results, we concluded that fruit flies could develop resistance to phenol by decreasing its toxicity; phenol was a inducer of glutathione S-transferases; phenol could increase the glutathione S-transferases enzymatic activities by increasing the amount of proteins; phenol exposure could decrease the benzene toxicity; no new glutathione S-transferase isozyme subunit was induced; and the level of GstD1 and GstD5 mRNAs did not significantly increase in phenol-treated strain.
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Mueller AL, Artman LD, Balandrin MF, Brady E, Chien Y, DelMar EG, Kierstead A, Marriott TB, Moe ST, Raszkiewicz JL, VanWagenen B, Wells D. NPS 1506, a moderate affinity uncompetitive NMDA receptor antagonist: preclinical summary and clinical experience. Amino Acids 2001; 19:177-9. [PMID: 11026487 DOI: 10.1007/s007260070047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
NPS Pharmaceuticals, Inc. (NPS) has synthesized a series of open-channel blockers with varying potencies at the NMDA receptor. NPS 1506 (Fig. 1) is a moderate affinity antagonist that inhibits NMDA/glycine-induced increases in cytosolic calcium in cultured rat cerebellar granule cells (IC50 = 476nM) and displaces the binding of [3H]MK-801 to rat cortical membranes (IC50 = 664nM).
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Mueller AL, Artman LD, Balandrin MF, Brady E, Chien Y, Delmar EG, George K, Kierstead A, Marriott TB, Moe ST, Newman MK, Raszkiewicz JL, Sanguinetti EL, van Wagenen BC, Wells D. NPS 1506, a novel NMDA receptor antagonist and neuroprotectant. Review of preclinical and clinical studies. Ann N Y Acad Sci 2000; 890:450-7. [PMID: 10668449 DOI: 10.1111/j.1749-6632.1999.tb08023.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
NPS 1506 is a moderate affinity, uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. NPS 1506 is neuroprotective in rodent models of ischemic stroke, hemorrhagic stroke, and head trauma, with a 2-hr window of opportunity. Neuroprotectant doses of NPS 1506 ranged from approximately 0.1-1.0 mg/kg, with peak plasma concentrations ranging from 8-80 ng/mL. Even at doses producing behavioral toxicity, NPS 1506 did not elicit MK-801-like behaviors, did not generalize to phencyclidine (PCP), and did not elicit neuronal vacuolization. In a Phase I study, intravenous (i.v.) doses of NPS 1506 from 5-100 mg were well tolerated and provided plasma concentrations in excess of those required for neuroprotection in rodents. Adverse events at the 100-mg dose included mild dizziness and lightheadedness, and mild to moderate ataxia. Neither PCP-like psychotomimetic effects nor cardiovascular effects were noted. The long plasma half-life of NPS 1506 (approximately 60 hr) suggests that a single i.v. dose will provide prolonged neuroprotection in humans.
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Crowley MP, Fahrer AM, Baumgarth N, Hampl J, Gutgemann I, Teyton L, Chien Y. A population of murine gammadelta T cells that recognize an inducible MHC class Ib molecule. Science 2000; 287:314-6. [PMID: 10634788 DOI: 10.1126/science.287.5451.314] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Although gammadelta T cells are implicated in regulating immune responses, gammadelta T cell-ligand pairs that could mediate such regulatory functions have not been identified. Here, the expression of the major histocompatibility complex (MHC) class Ib T22 and the closely related T10 molecules is shown to be activation-induced, and they confer specificity to about 0.4% of the gammadelta T cells in normal mice. Thus, the increased expression of T22 and/or T10 might trigger immunoregulatory gammadelta T cells during immune responses. Furthermore, the fast on-rates and slow off-rates that characterize this receptor/ligand interaction would compensate for the low ligand stability and suggest a high threshold for gammadelta T cell activation.
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MESH Headings
- Animals
- CHO Cells
- Cricetinae
- Dimerization
- Histocompatibility Antigens Class I/immunology
- Histocompatibility Antigens Class I/metabolism
- Ligands
- Lymphocyte Activation
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Transgenic
- Proteins/immunology
- Proteins/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Spleen/cytology
- Spleen/immunology
- T-Lymphocyte Subsets/immunology
- beta 2-Microglobulin/immunology
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Wingren C, Crowley MP, Degano M, Chien Y, Wilson IA. Crystal structure of a gammadelta T cell receptor ligand T22: a truncated MHC-like fold. Science 2000; 287:310-4. [PMID: 10634787 DOI: 10.1126/science.287.5451.310] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Murine T10 and T22 are highly related nonclassical major histocompatibility complex (MHC) class Ib proteins that bind to certain gammadelta T cell receptors (TCRs) in the absence of other components. The crystal structure of T22b at 3.1 angstroms reveals similarities to MHC class I molecules, but one side of the normal peptide-binding groove is severely truncated, which allows direct access to the beta-sheet floor. Potential gammadelta TCR-binding sites can be inferred from functional mapping of T10 and T22 point mutants and allelic variants. Thus, T22 represents an unusual variant of the MHC-like fold and indicates that gammadelta and alphabeta TCRs interact differently with their respective MHC ligands.
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MESH Headings
- Alleles
- Amino Acid Substitution
- Animals
- Binding Sites
- Crystallography, X-Ray
- Glycosylation
- Histocompatibility Antigens Class I/chemistry
- Hydrogen Bonding
- Ligands
- Mice
- Models, Molecular
- Point Mutation
- Protein Conformation
- Protein Folding
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proteins/chemistry
- Proteins/immunology
- Proteins/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Surface Properties
- beta 2-Microglobulin/chemistry
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Chien Y, Manna AC, Projan SJ, Cheung AL. SarA, a global regulator of virulence determinants in Staphylococcus aureus, binds to a conserved motif essential for sar-dependent gene regulation. J Biol Chem 1999; 274:37169-76. [PMID: 10601279 DOI: 10.1074/jbc.274.52.37169] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The expression of many virulence determinants in Staphylococcus aureus including alpha-hemolysin-, protein A-, and fibronectin-binding proteins is controlled by global regulatory loci such as sar and agr. In addition to controlling target gene expression via agr (e.g. alpha-hemolysin), the sar locus can also regulate target gene transcription via agr-independent mechanisms. In particular, we have found that SarA, the major regulatory protein encoded within sar, binds to a conserved sequence, homologous to the SarA-binding site on the agr promoter, upstream of the -35 promoter boxes of several target genes including hla (alpha-hemolysin gene), spa (protein A gene), fnb (fibronectin-binding protein genes), and sec (enterotoxin C gene). Deletion of the SarA recognition motif in the promoter regions of agr and hla in shuttle plasmids rendered the transcription of these genes undetectable in agr and hla mutants, respectively. Likewise, the transcription activity of spa (a gene normally repressed by sar), as measured by a XylE reporter fusion assay, became derepressed in a wild type strain containing a shuttle plasmid in which the SarA recognition site had been deleted from the spa promoter region. However, DNase I footprinting assays demonstrated that the SarA-binding region on the spa and hla promoter is more extensive than the predicted consensus sequence, thus raising the possibility that the consensus sequence is an activation site within a larger binding region. Because the sar and agr regulate an assortment of virulence factors in S. aureus, we propose, based on our data, a unifying hypothesis for virulence gene activation in S. aureus whereby SarA is a regulatory protein that binds to its consensus SarA recognition motif to activate (e.g. hla) or repress (e.g. spa) the transcription of sar target genes, thus accounting for both agr-dependent and agr-independent mode of regulation.
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Moe ST, Shimizu SM, Smith DL, Van Wagenen BC, DelMar EG, Balandrin MF, Chien Y, Raszkiewicz JL, Artman LD, Mueller AL, Lobkovsky E, Clardy J. Synthesis, biological activity, and absolute stereochemical assignment of NPS 1392: a potent and stereoselective NMDA receptor antagonist. Bioorg Med Chem Lett 1999; 9:1915-20. [PMID: 10450953 DOI: 10.1016/s0960-894x(99)00317-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The synthesis, biological activity, and single crystal X-ray structure of NPS 1392, (R)-(-)-3,3-bis(3-fluorophenyl)-2-methylpropan-1-amine (3a), a potent, stereoselective antagonist of the NMDA receptor, are described. The NMDA receptor selectively bound the levo isomer (3a) over its enantiomer (3b), which prompted a rigorous absolute configuration assignment. NPS 1392 has the R configuration based on the single-crystal X-ray diffraction analysis of the hydroiodide salt of NPS 1392. This compound is a potential neuroprotective agent for use in the treatment of ischemic stroke.
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Abstract
The control of virulence determinant expression in Staphylococcus aureus is a complex process involving global regulatory loci such as sar and agr. The sar locus consists of a 372 bp sarA open reading frame (ORF) preceded by a triple promoter region interspersed with two putative smaller ORFs (ORF3 and ORF4). The triple promoter system yields three overlapping sar transcripts (sarA, sarC and sarB of 0.56, 0.8 and 1.2 kb respectively). We have recently shown that the SarA protein binds to the agr promoter region to stimulate the transcription of RNAII and RNAIII, two major transcripts encoded within the agr locus. To assess the role of the region upstream of sarA in agr expression, we evaluated the contribution of ORF3 and ORF4 to SarA protein expression and to agr activation by introducing nonsense mutations into the respective ORFs. Northern analysis of sar mutant clones containing these mutations carried on a shuttle plasmid revealed that all three sar-related transcripts are present. Using anti-SarA monoclonal antibodies with defined epitopes in a competitive ELISA to determine the SarA protein level, we found that the introduction of a stop codon in ORF3 on a shuttle plasmid carrying the intact sar locus in a sar mutant led to a significant decrease in SarA protein level compared with the non-mutated control. The effect of a nonsense mutation in ORF4 on SarA levels is much less. Likewise, an analogous sar mutant clone with a deletion in ORF3 also displayed a lower SarA level than its intact counterpart. The reduction in SarA expression correlated with a lower level of agr activation in the corresponding sar mutant clone. These data suggest that ORF3, and to a lesser degree ORF4, may affect agr expression by modulating SarA protein expression.
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Davis MM, Boniface JJ, Reich Z, Lyons D, Hampl J, Arden B, Chien Y. Ligand recognition by alpha beta T cell receptors. Annu Rev Immunol 1998; 16:523-44. [PMID: 9597140 DOI: 10.1146/annurev.immunol.16.1.523] [Citation(s) in RCA: 715] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
While still incomplete, the first data concerning the biochemistry of T cell receptor-ligand interactions in cell-free systems seem to have considerable predictive value regarding whether a T cell response is strong or weak or suppressive. This data will help considerably in elucidating the mechanisms behind T cell responsiveness. Also of great interest are the first structures of T cell receptor molecules and, particularly, TCR-ligand complexes. These appear to confirm earlier suggestions of a fixed orientation for TCR engagement with peptide/MHC and should form the basis for understanding higher oligomers, evidence for which has also just emerged. We conclude with an analysis of the highly diverse CDR3 loops found in all antigen receptor molecules and suggest that such regions form the core of both TCR and antibody specificity.
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Chien Y, Helmann JD, Zinder SH. Interactions between the promoter regions of nitrogenase structural genes (nifHDK2) and DNA-binding proteins from N2- and ammonium-grown cells of the archaeon Methanosarcina barkeri 227. J Bacteriol 1998; 180:2723-8. [PMID: 9573159 PMCID: PMC107226 DOI: 10.1128/jb.180.10.2723-2728.1998] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Transcription initiation in Archaea (archaebacteria) resembles the eucaryotic process, having been shown to involve TATA box-like promoter regions as well as TATA-binding protein and TFIIB homologs. However, little is known about transcription regulation in archaea. We have previously demonstrated that transcripts of nifHDK2 genes, encoding Methanosarcina barkeri nitrogenase, are present in N2-grown cells but not in ammonium-grown cells, indicating that nif transcription is regulated by the nitrogen source. In this study, we detected proteins in M. barkeri cell extracts that bind specifically to DNA containing the putative promoter region of nifHDK2. No binding was found when the promoter region was deleted from the DNA. A competition assay showed that the methyl coenzyme M reductase (mcr) promoter region DNA and the nifH2 promoter region DNA competed for a common factor(s). There was no binding to the nifH2 promoter region by extracts of ammonium-grown cells, but there was binding by these extracts to promoter regions for mcr genes, which are presumably constitutively expressed. Interestingly, extracts of ammonium-grown cells inhibited binding to the nif promoter region by extracts of N2-grown cells. Fractionation of extracts of ammonium-grown cells with a heparin-Sepharose column resolved them into a fraction eluting at 0 M NaCl, which inhibited binding by extracts of N2-grown cells, and a fraction eluting at 0.5 to 0.75 M NaCl, which showed binding to the promoter region. These results are congruent with a model for regulation of nif gene expression in M. barkeri in which a substance present in ammonium-grown cells inhibits DNA binding by a transcription-associated protein or proteins.
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Chien Y, Cheung AL. Molecular interactions between two global regulators, sar and agr, in Staphylococcus aureus. J Biol Chem 1998; 273:2645-52. [PMID: 9446568 DOI: 10.1074/jbc.273.5.2645] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The expression of many virulence determinants in Staphylococcus aureus is controlled by regulatory loci such as agr and sar. We have previously shown that the SarA protein is required for optimal transcription of RNAII and RNAIII in the agr locus. To define the specific molecular interaction, we overexpressed SarA as a glutathione S-transferase (GST) fusion protein by cloning the 372-base pair (bp) sarA gene into the vector. The purified GST-SarA as well as cleaved SarA were able to bind specifically to the P2, P3, and the combined P2-P3 promoter fragments of agr in gel shift assays. Using monoclonal antibodies to SarA, we found that SarA is a part of the retarded protein-DNA complex as evidenced by the formation of a supershifted band. The SarA binding site on the agr promoter, mapped by DNase I footprinting assay, covered a 29-bp region between the P2 and P3 promoters devoid of any direct repeats. A synthetic 45-bp fragment encompassing the 29-bp sequence also bound the SarA protein in band shift assays. Serial in-frame deletion analysis of sarA revealed that, with the exception of 15 residues in the N terminus, almost all of SarA (residues 16-124) is essential for agr binding activity. Northern analysis confirmed that only the sar mutant clone containing a truncated sarA gene with a 15-residue deletion in the N terminus (SarA16-124) could activate agr transcription to a level approaching that of the full-length counterpart (SarA1-124). Taken together, these data indicated that SarA is a DNA-binding protein with binding specificity to the P2 and P3 interpromoter region of agr, thereby activating RNAII and RNAIII transcription.
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Moe ST, Smith DL, Chien Y, Raszkiewicz JL, Artman LD, Mueller AL. Design, synthesis, and biological evaluation of spider toxin (argiotoxin-636) analogs as NMDA receptor antagonists. Pharm Res 1998; 15:31-8. [PMID: 9487543 DOI: 10.1023/a:1011988317683] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE Twelve synthetic spider toxin analogs were prepared in an effort to better understand the structure-activity relationships of the polyamine portion of argiotoxin-636 (Arg-636), a noncompetitive NMDA receptor (NMDAR) antagonist. METHODS The 1,13-diamino-4,8-diazatridecane portion of the side chain of Arg-636 was systematically modified in an effort to further our knowledge of the structural requirements for the alkyl linker spacing between the amine nitrogens. Systematic isosteric replacement of each of the amine nitrogens in the polyamine moiety with either oxygen or carbon provided a series of compounds which were evaluated in vitro for NMDAR antagonist activity. RESULTS One-half of the heteroatoms found in Arg-636 were removed to provide analogs which maintained in vitro potency below 1 microM. However, these simplified analogs produced similar or more pronounced effects on the cardiovascular system than Arg-636 in vivo. CONCLUSIONS In this set of analogs, a minimum of three basic nitrogens in the side chain was required for maximum potency as NMDAR antagonists. Isosteric nitrogen substitutions in the polyamine chain reduced the in vitro potency of these analogs. An analog binding-conformation model was proposed to rationalize the inactivity of these isosterically substituted analogs.
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Maymó-Gatell X, Chien Y, Gossett JM, Zinder SH. Isolation of a bacterium that reductively dechlorinates tetrachloroethene to ethene. Science 1997; 276:1568-71. [PMID: 9171062 DOI: 10.1126/science.276.5318.1568] [Citation(s) in RCA: 634] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tetrachloroethene is a prominent groundwater pollutant that can be reductively dechlorinated by mixed anaerobic microbial populations to the nontoxic product ethene. Strain 195, a coccoid bacterium that dechlorinates tetrachloroethene to ethene, was isolated and characterized. Growth of strain 195 with H2 and tetrachloroethene as the electron donor and acceptor pair required extracts from mixed microbial cultures. Growth of strain 195 was resistant to ampicillin and vancomycin; its cell wall did not react with a peptidoglycan-specific lectin and its ultrastructure resembled S-layers of Archaea. Analysis of the 16S ribosomal DNA sequence of strain 195 indicated that it is a eubacterium without close affiliation to any known groups.
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Crowley MP, Reich Z, Mavaddat N, Altman JD, Chien Y. The recognition of the nonclassical major histocompatibility complex (MHC) class I molecule, T10, by the gammadelta T cell, G8. J Exp Med 1997; 185:1223-30. [PMID: 9104809 PMCID: PMC2196254 DOI: 10.1084/jem.185.7.1223] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Recent studies have shown that many nonclassical major histocompatibility complex (MHC) (class 1b) molecules have distinct antigen-binding capabilities, including the binding of nonpeptide moieties and the binding of peptides that are different from those bound to classical MHC molecules. Here, we show that one of the H-2T region-encoded molecules, T10, when produced in Escherichia coli, can be folded in vitro with beta2-microglobulin (beta2m) to form a stable heterodimer in the absence of peptide or nonpeptide moieties. This heterodimer can be recognized by specific antibodies and is stimulatory to the gammadelta T cell clone, G8. Circular dichroism analysis indicates that T10/beta2m has structural features distinct from those of classical MHC class I molecules. These results suggest a new way for MHC-like molecules to adopt a peptide-free structure and to function in the immune system.
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Davis MM, Lyons DS, Altman JD, McHeyzer-Williams M, Hampl J, Boniface JJ, Chien Y. T cell receptor biochemistry, repertoire selection and general features of TCR and Ig structure. CIBA FOUNDATION SYMPOSIUM 1997; 204:94-100; discussion 100-4. [PMID: 9107414 DOI: 10.1002/9780470515280.ch7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
T cell recognition is a central event in the development of most immune responses, whether appropriate or inappropriate (i.e. autoimmune). We are interested in reducing T cell recognition to its most elemental components and relating this to biological outcome. In a model system involving a cytochrome c-specific I-Ek restricted T cell receptor (TCR) derived from the 2B4 hybridoma, we have studied the interaction of soluble TCR and soluble peptide-MHC complexes using surface plasmon resonance. We find a striking continuum in which biological activity correlates best with the dissociation rate of the TCR from the peptide-MHC complex. In particular, we have found that weak agonists have significantly faster off-rates than strong agonists and that antagonists have even faster off-rates. This suggests that the stability of TCR binding to a given ligand is critically important with respect to whether the T cell is stimulated, inhibited or remains indifferent. It also suggests that the phenomenon of peptide antagonists might be explained purely by kinetic models and that conformation, either inter- or intramolecular, may not be a factor. We have also studied TCR repertoire selection during the establishment of a cytochrome c response, initially using an anti-TCR antibody strategy, but more recently using peptide-MHC tetramers as antigen-specific staining reagents. These tetramers work well with either class I or class II MHC-specific TCRs and have many possible applications. Lastly, we have also tried to correlate the structural and genetic features of TCRs with their function. Recent data on TCR structure as well as previous findings with antibodies suggest that both molecules are highly dependent on CDR3 length and sequence variation to form specific contacts with antigens. This suggests a general "logic' behind TCR and Ig genetics as it relates to structure and function that helps to explain certain anomalous findings and makes a number of clear predictions.
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Lyons DS, Lieberman SA, Hampl J, Boniface JJ, Chien Y, Berg LJ, Davis MM. A TCR binds to antagonist ligands with lower affinities and faster dissociation rates than to agonists. Immunity 1996; 5:53-61. [PMID: 8758894 DOI: 10.1016/s1074-7613(00)80309-x] [Citation(s) in RCA: 345] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
T lymphocyte activation is mediated by the interaction of specific TCR with antigenic peptides bound to MHC molecules. Single amino acid substitutions are often capable of changing the effect of a peptide from stimulatory to antagonistic. Using surface plasmon resonance, we have analyzed the interaction between a complex consisting of variants of the MCC peptide bound to a mouse class II MHC (Ek) and a specific TCR. Using both an improved direct binding method as well as a novel inhibition assay, we show that the affinities of three different antagonist peptide-Ek complexes are approximately 10-50 times lower than that of the wildtype MCC-Ek complex for the TCR, largely due to an increased off-rate. These results suggest that the biological effects of peptide antagonists and partial agonists may be largely based on kinetic parameters.
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Davis MM, Chien Y. Issues concerning the nature of antigen recognition by alpha beta and gamma delta T-cell receptors. IMMUNOLOGY TODAY 1995; 16:316-8. [PMID: 7576062 DOI: 10.1016/0167-5699(95)80143-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Deckhut AM, Chien Y, Blackman MA, Woodland DL. Evidence for a functional interaction between the beta chain of major histocompatibility complex class II and the T cell receptor alpha chain during recognition of a bacterial superantigen. J Exp Med 1994; 180:1931-5. [PMID: 7964468 PMCID: PMC2191731 DOI: 10.1084/jem.180.5.1931] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Several studies have suggested that there is a direct interaction between the T cell receptor (TCR) and the major histocompatibility complex (MHC) molecule during T cell recognition of superantigen. To further investigate this possibility, we have analyzed T cell recognition of a bacterial superantigen, Staphylococcal enterotoxin B (SEB), presented by a series of mutant murine I-Ek molecules in which residues of either the alpha or beta chain predicted to interact with the TCR have been substituted. Individual T cell hybridomas gave distinct patterns of responsiveness to SEB presented by the I-E beta k mutants that could not be attributed to differences in the binding of SEB to the mutants. This effect appeared to be dependent on the TCR-alpha chain because some of these hybridomas expressed identical TCR transgenic beta chains. In contrast, none of the hybridomas gave distinct patterns of responsiveness to SEB presented by the I-E alpha k mutants. Taken together, these observations support the idea that there is a functional interaction between the alpha chain of the TCR and the beta chain of the MHC class II molecule. The data also support the idea that this interaction might enhance superantigen recognition in some cases.
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Davis MM, Chien Y. Topology and affinity of T-cell receptor mediated recognition of peptide-MHC complexes. Curr Opin Immunol 1993; 5:45-9. [PMID: 8452673 DOI: 10.1016/0952-7915(93)90079-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Significant progress has been made on several long-standing issues regarding T-cell receptor mediated recognition of antigen-MHC complexes. For one, early data suggest that the affinity of the T-cell receptor for the peptide-MHC complex is extremely low, with a KD of approximately 10(-4)-10(-5)M, much weaker than most antibody-antigen interactions. The fact that this affinity is lower than that of some T-cell adhesion molecules for their ligands could have important implications for immune surveillance. A second area of interest is the topology of T-cell receptor recognition; evidence of direct contact between the third complementarity determining region of the T-cell receptor and peptide determinants has been obtained. In addition, the orientation of the T-cell receptor with respect to several antigen-MHC complexes has been predicted. They suggest that whereas most or all peptides seem to bind in the same orientation in both class I and class II MHC molecules, the orientation of the T-cell receptor over the peptide-MHC complex may not be fixed.
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Frohlich ED, Chien Y, Sesoko S, Pegram BL. Relationship between dietary sodium intake, hemodynamics, and cardiac mass in SHR and WKY rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 264:R30-4. [PMID: 8430884 DOI: 10.1152/ajpregu.1993.264.1.r30] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To study the effects of sodium intake on circulatory homeostasis and cardiac structure, changes in cardiac mass, systemic hemodynamics, and organ blood flows were determined in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats after 10 wk of controlled dietary intake of low sodium (0.01%), standard sodium (0.44%), and high sodium (2 levels: 1.44 and 4%). Systemic and regional hemodynamics were measured in conscious rats using the radioactive microsphere reference method. The various dietary sodium manipulations did not cause any changes in systemic and regional hemodynamics in the WKY rats. In contrast, the high-sodium diets increased arterial pressure and total peripheral resistance progressively in the SHR rats while decreasing cardiac index, heart rate, and organ blood flows to heart, kidneys, and splanchnic area. The higher sodium intake (4%) increased total and left ventricular mass index in both the SHR and the WKY rats even though hemodynamics of the WKY rats remained unchanged. These data indicate that the high-sodium diet, in addition to producing general vasoconstriction and exacerbation of hypertension, increased cardiac mass further in SHR rats; it also increased cardiac mass in the WKY rats independent of arterial pressure changes, suggesting that high sodium intake may be an independent pathogenetic factor for the development of cardiac hypertrophy.
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Frohlich ED, Sasaki O, Chien Y, Arita M. Changes in cardiovascular mass, left ventricular pumping ability and aortic distensibility after calcium antagonists in Wistar-Kyoto and spontaneously hypertensive rats. J Hypertens 1992; 10:1369-78. [PMID: 1336522 DOI: 10.1097/00004872-199211000-00009] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES To determine the effects of different dihydropyridine calcium antagonists on cardiovascular mass and function in normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). METHODS The rats were treated daily for 3 weeks with nitrendipine (20 mg/kg), nifedipine (30 mg/kg), nisoldipine (6 mg/kg) or their vehicles. At the conclusion of that period left ventricular pumping ability and aortic distensibility were determined, and the aortic, cardiac and left and right ventricular masses. RESULTS Each drug reduced arterial pressure in both rat strains; each decreased left ventricular mass in SHR but not in WKY rats. All three agents increased right ventricular mass in WKY rats; only nisoldipine did so in SHR. Each compound improved left ventricular pumping ability in WKY rats, maintaining function even when pressure was abruptly increased to pretreatment levels. In contrast, although all three calcium antagonists improved cardiac performance in SHR at the pharmacologically reduced pressures, pumping ability was not maintained when pressure was increased to pretreatment levels in nisoldipine-treated SHR. All three agents improved aortic distensibility in both strains, but only in SHR was reduced aortic mass demonstrated. CONCLUSIONS These data not only continue to demonstrate a functional/structural dissociation associated with antihypertensive therapy, but also suggest subtle functional and structural effects that differ even within the same class of calcium antagonists.
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Chien Y, Frohlich ED, MacPhee AA, Pegram BL. Quinaprilat increases total body vascular compliance in rats with myocardial infarction. Chin Med J (Engl) 1992; 105:382-9. [PMID: 1499368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
To test whether quinaprilat, a new angiotensin converting enzyme inhibitor, has any venous effect, its immediate effects were measured on mean circulatory filling pressure (MCFP), intravascular volume and total body vascular (i.e., venous) compliance in conscious rats with mild congestive heart failure induced by coronary artery ligation. MCFP was determined by inflating a right atrial balloon to arrest the circulation instantly and temporarily. Total body vascular compliance was derived from total circulatory pressure-volume relationships as determined by series measurements of MCFP with different intravascular volume status. In 8 rats with mean infarct size of 26 +/- 4%, 30-minute infusion of quinaprilat (0.1 mg/kg/min) decreased both mean arterial and central venous pressures by 8 mmHg and 0.7 mmHg, respectively (P less than 0.02); heart rate, MCFP, hematocrit and blood volume remained unchanged. Compared with control vehicle infusion, quinaprilat increased the total body vascular compliance (2.09 +/- 0.12 vs 2.69 +/- 0.23 ml/kg/mmHg; P less than 0.05) and decreased extrapolated unstressed circulating volume (34.96 +/- 1.10 vs 28.53 +/- 2.55 ml/kg; P less than 0.02). These data suggest that quinaprilat produces possible venodilation through immediately improved total body vascular compliance thereby reducing cardiac preload in this rat model of chronic heart failure.
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