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Forbes CD, Toth JG, Ozbal CC, Lamarr WA, Pendleton JA, Rocks S, Gedrich RW, Osterman DG, Landro JA, Lumb KJ. High-Throughput Mass Spectrometry Screening for Inhibitors of Phosphatidylserine Decarboxylase. ACTA ACUST UNITED AC 2016; 12:628-34. [PMID: 17478478 DOI: 10.1177/1087057107301320] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A high-throughput mass spectrometry assay to measure the catalytic activity of phosphatidylserine decarboxylase (PISD) is described. PISD converts phosphatidylserine to phosphatidylethanolamine during lipid synthesis. Traditional methods of measuring PISD activity are low throughput and unsuitable for the high-throughput screening of large compound libraries. The high-throughput mass spectrometry assay directly measures phosphatidylserine and phosphatidylethanolamine using the RapidFire™ platform at a rate of 1 sample every 7.5 s. The assay is robust, with an average Z′ value of 0.79 from a screen of 9920 compounds. Of 60 compounds selected for confirmation, 54 are active in dose-response studies. The application of high-throughput mass spectrometry permitted a high-quality screen to be performed for an otherwise intractable target. ( Journal of Biomolecular Screening 2007:628-634)
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Affiliation(s)
- Chris D Forbes
- Department of Research Technologies, Bayer Pharmaceuticals Corporation, West Haven, CT 06516, USA
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Smith R, Duguay A, Bakker A, Li P, Weiszmann J, Thomas MR, Alba BM, Wu X, Gupte J, Yang L, Stevens J, Hamburger A, Smith S, Chen J, Komorowski R, Moore KW, Véniant MM, Li Y. FGF21 can be mimicked in vitro and in vivo by a novel anti-FGFR1c/β-Klotho bispecific protein. PLoS One 2013; 8:e61432. [PMID: 23630589 PMCID: PMC3632592 DOI: 10.1371/journal.pone.0061432] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 03/09/2013] [Indexed: 12/14/2022] Open
Abstract
The endocrine hormone FGF21 has attracted considerable interest as a potential therapeutic for treating diabetes and obesity. As an alternative to the native cytokine, we generated bispecific Avimer polypeptides that bind with high affinity and specificity to one of the receptor and coreceptor pairs used by FGF21, FGFR1c and β-Klotho. These Avimers exhibit FGF21-like activity in in vitro assays with potency greater than FGF21. In a study conducted in obese male cynomolgus monkeys, animals treated with an FGFR1c/β-Klotho bispecific Avimer showed improved metabolic parameters and reduced body weight comparable to the effects seen with FGF21. These results not only demonstrate the essential roles of FGFR1c and β-Klotho in mediating the metabolic effects of FGF21, they also describe a first bispecific activator of this unique receptor complex and provide validation for a novel therapeutic approach to target this potentially important pathway for treating diabetes and obesity.
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Affiliation(s)
- Richard Smith
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Amy Duguay
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Alice Bakker
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Peng Li
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Jennifer Weiszmann
- Metabolic Disorders, Amgen Inc., South San Francisco, California, United States of America
| | - Melissa R. Thomas
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Benjamin M. Alba
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Xinle Wu
- Metabolic Disorders, Amgen Inc., South San Francisco, California, United States of America
| | - Jamila Gupte
- Metabolic Disorders, Amgen Inc., South San Francisco, California, United States of America
| | - Li Yang
- Metabolic Disorders, Amgen Inc., South San Francisco, California, United States of America
| | - Jennitte Stevens
- Therapeutic Discovery, Amgen Inc., Thousand Oaks, California, United States of America
| | - Agnes Hamburger
- Therapeutic Discovery, Amgen Inc., Thousand Oaks, California, United States of America
| | - Stephen Smith
- Therapeutic Discovery, Amgen Inc., Thousand Oaks, California, United States of America
| | - Jiyun Chen
- Pharmacokinetics and Drug Metabolism, Amgen Inc., South San Francisco, California, United States of America
| | - Renee Komorowski
- Metabolic Disorders, Amgen Inc., Thousand Oaks, California, United States of America
| | - Kevin W. Moore
- Therapeutic Discovery, Amgen Inc., South San Francisco, California, United States of America
| | - Murielle M. Véniant
- Metabolic Disorders, Amgen Inc., Thousand Oaks, California, United States of America
| | - Yang Li
- Metabolic Disorders, Amgen Inc., South San Francisco, California, United States of America
- * E-mail:
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Subauste AR, Das AK, Li X, Elliot B, Evans C, El Azzouny M, Treutelaar M, Oral E, Leff T, Burant CF. Alterations in lipid signaling underlie lipodystrophy secondary to AGPAT2 mutations. Diabetes 2012; 61:2922-31. [PMID: 22872237 PMCID: PMC3478532 DOI: 10.2337/db12-0004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Congenital generalized lipodystrophy (CGL), secondary to AGPAT2 mutation is characterized by the absence of adipocytes and development of severe insulin resistance. In the current study, we investigated the adipogenic defect associated with AGPAT2 mutations. Adipogenesis was studied in muscle-derived multipotent cells (MDMCs) isolated from vastus lateralis biopsies obtained from controls and subjects harboring AGPAT2 mutations and in 3T3-L1 preadipocytes after knockdown or overexpression of AGPAT2. We demonstrate an adipogenic defect using MDMCs from control and CGL human subjects with mutated AGPAT2. This defect was rescued in CGL MDMCs with a retrovirus expressing AGPAT2. Both CGL-derived MDMCs and 3T3-L1 cells with knockdown of AGPAT2 demonstrated an increase in cell death after induction of adipogenesis. Lack of AGPAT2 activity reduces Akt activation, and overexpression of constitutively active Akt can partially restore lipogenesis. AGPAT2 modulated the levels of phosphatidic acid, lysophosphatidic acid, phosphatidylinositol species, as well as the peroxisome proliferator-activated receptor γ (PPARγ) inhibitor cyclic phosphatidic acid. The PPARγ agonist pioglitazone partially rescued the adipogenic defect in CGL cells. We conclude that AGPAT2 regulates adipogenesis through the modulation of the lipome, altering normal activation of phosphatidylinositol 3-kinase (PI3K)/Akt and PPARγ pathways in the early stages of adipogenesis.
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Affiliation(s)
- Angela R. Subauste
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Arun K. Das
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Xiangquan Li
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Brandon Elliot
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Charles Evans
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | | | - Mary Treutelaar
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Elif Oral
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Todd Leff
- Department of Pathology, Wayne State University, Detroit, Michigan
| | - Charles F. Burant
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
- Corresponding author: Charles F. Burant,
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Skottrup PD, Sørensen G, Ksiazek M, Potempa J, Riise E. A phage display selected 7-mer peptide inhibitor of the Tannerella forsythia metalloprotease-like enzyme Karilysin can be truncated to Ser-Trp-Phe-Pro. PLoS One 2012; 7:e48537. [PMID: 23119051 PMCID: PMC3485312 DOI: 10.1371/journal.pone.0048537] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 09/26/2012] [Indexed: 01/19/2023] Open
Abstract
Tannerella forsythia is a gram-negative bacteria, which is strongly associated with the development of periodontal disease. Karilysin is a newly identified metalloprotease-like enzyme, that is secreted from T. forsythia. Karilysin modulates the host immune response and is therefore considered a likely drug target. In this study peptides were selected towards the catalytic domain from Karilysin (Kly18) by phage display. The peptides were linear with low micromolar binding affinities. The two best binders (peptide14 and peptide15), shared the consensus sequence XWFPXXXGGG. A peptide15 fusion with Maltose Binding protein (MBP) was produced with peptide15 fused to the N-terminus of MBP. The peptide15-MBP was expressed in E. coli and the purified fusion-protein was used to verify Kly18 specific binding. Chemically synthesised peptide15 (SWFPLRSGGG) could inhibit the enzymatic activity of both Kly18 and intact Karilysin (Kly48). Furthermore, peptide15 could slow down the autoprocessing of intact Kly48 to Kly18. The WFP motif was important for inhibition and a truncation study further demonstrated that the N-terminal serine was also essential for Kly18 inhibition. The SWFP peptide had a Ki value in the low micromolar range, which was similar to the intact peptide15. In conclusion SWFP is the first reported inhibitor of Karilysin and can be used as a valuable tool in structure-function studies of Karilysin.
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Affiliation(s)
- Peter Durand Skottrup
- Biomolecular Interaction Group, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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Mullett SJ, Di Maio R, Greenamyre JT, Hinkle DA. DJ-1 expression modulates astrocyte-mediated protection against neuronal oxidative stress. J Mol Neurosci 2012; 49:507-11. [PMID: 23065353 DOI: 10.1007/s12031-012-9904-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 10/08/2012] [Indexed: 12/21/2022]
Abstract
DJ-1 deficiency is a cause of genetic Parkinson's disease (PARK7 PD). In sporadic Parkinson's disease (PD), however, DJ-1 is abundantly expressed in reactive astrocytes. This may represent a compensatory protective response. In initial support of this hypothesis, we have shown in vitro that DJ-1-overexpressing astrocytes protect neurons against rotenone-induced death. Rotenone, a pesticide linked to increased PD risk, can stimulate oxidative stress. This process is implicated in PD pathogenesis. Since DJ-1 can enhance antioxidant systems, we hypothesized that augmenting its expression in astrocytes would protect cocultured neurons against oxidative stress. We report here that DJ-1-overexpressing astrocytes were significantly more protective against rotenone-induced neuronal thiol oxidation than wild-type astrocytes in neuron-astrocyte cocultures. DJ-1-knockdown astrocytes, on the other hand, were significantly impaired in their capacity to protect neurons against thiol oxidation. Each of these findings was replicated using astrocyte-conditioned media on neuron-enriched cultures. Thus, DJ-1-modulated, astrocyte-released soluble factors must be involved in the mechanism. This is the first demonstration that the manipulation of a PD-causing gene in astrocytes affects their ability to protect neurons against oxidative stress.
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Affiliation(s)
- Steven J Mullett
- Department of Neurology and Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Zheng L, Liang P, Li J, Huang XB, Liu SC, Zhao HZ, Han KQ, Wang Z. ShRNA-targeted COMMD7 suppresses hepatocellular carcinoma growth. PLoS One 2012; 7:e45412. [PMID: 23049798 PMCID: PMC3458015 DOI: 10.1371/journal.pone.0045412] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 08/21/2012] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND COMMD7 is a newly identified gene overexpressed in hepatocellular carcinoma (HCC) and associated with tumor invasion and poor prognosis. We aim to examine the biological function of COMMD7 in HCC by shRNA silencing. METHODS COMMD7 expressions were examined in human HCC cell lines HepG2, Huh7, Hep3B, HLE, HLF, SK-Hep-1 and PLC/PRF/5 cells. Recombinant pGenesil-COMMD7-shRNA was transfected into COMMD7-abundant HepG2 cells to silence COMMD7 expression. The effects of COMMD7 silencing on HepG2 cell proliferation in vitro and xenograft tumor growth in vivo were evaluated. Flow cytometry profiling was used to detect the presence of apoptosis in COMMD7-silenced HepG2 cells and to differentiate cell cycle distribution. Electrophoretic mobility shift assay and luciferase reporter assays to examine the activities of nuclear factor-kappaB (NF-κB) signaling pathways in response to tumor necrosis factor (TNF)-α in COMMD7-silenced HepG2 cells. RESULTS COMMD7 expression level was abundance in HepG2 and SK-Hep-1 cells. COMMD7 was aberrantly overexpressed in HepG2 cells, whilst pGenesil-COMMD7-shRNA exhibited a maximal inhibition rate of 75%. COMMD7 silencing significantly reduced HepG2 cell proliferation and colony formation. The knockdown of COMMD7 resulted in an increased apoptosis and cell cycle arrest at S-phase. COMMD7 knockdown also exhibited an antineoplastic effect in vivo, which manifested as tumor xenograft growth retardation. COMMD7 silencing also suppressed the responsiveness of NF-κB signaling pathway to the stimulation with TNF-α in vitro. Moreover, the similar suppressive effects of COMMD7 silence on SK-Hep-1 cells were also observed. CONCLUSIONS COMMD7 contributes to HCC progression by reducing cell apoptosis and overcoming cell cycle arrest. The proliferative and antiapoptotic effects of COMMD7 may be mediated by NF-κB signaling pathway.
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Affiliation(s)
- Lu Zheng
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
| | - Ping Liang
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
- * E-mail: (PL); (JL)
| | - Jing Li
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
- * E-mail: (PL); (JL)
| | - Xiao-bing Huang
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
| | - Shi-cheng Liu
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
| | - Hong-zhi Zhao
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
| | - Ke-qiang Han
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
| | - Zheng Wang
- Department of Hepatobiliary Surgery, Xinqiao Hospital, the Third Military Medical University, Chongqing, China
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Nieborowska-Skorska M, Kopinski PK, Ray R, Hoser G, Ngaba D, Flis S, Cramer K, Reddy MM, Koptyra M, Penserga T, Glodkowska-Mrowka E, Bolton E, Holyoake TL, Eaves CJ, Cerny-Reiterer S, Valent P, Hochhaus A, Hughes TP, van der Kuip H, Sattler M, Wiktor-Jedrzejczak W, Richardson C, Dorrance A, Stoklosa T, Williams DA, Skorski T. Rac2-MRC-cIII-generated ROS cause genomic instability in chronic myeloid leukemia stem cells and primitive progenitors. Blood 2012; 119:4253-63. [PMID: 22411871 PMCID: PMC3359741 DOI: 10.1182/blood-2011-10-385658] [Citation(s) in RCA: 121] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 03/06/2012] [Indexed: 11/20/2022] Open
Abstract
Chronic myeloid leukemia in chronic phase (CML-CP) is induced by BCR-ABL1 oncogenic tyrosine kinase. Tyrosine kinase inhibitors eliminate the bulk of CML-CP cells, but fail to eradicate leukemia stem cells (LSCs) and leukemia progenitor cells (LPCs) displaying innate and acquired resistance, respectively. These cells may accumulate genomic instability, leading to disease relapse and/or malignant progression to a fatal blast phase. In the present study, we show that Rac2 GTPase alters mitochondrial membrane potential and electron flow through the mitochondrial respiratory chain complex III (MRC-cIII), thereby generating high levels of reactive oxygen species (ROS) in CML-CP LSCs and primitive LPCs. MRC-cIII-generated ROS promote oxidative DNA damage to trigger genomic instability, resulting in an accumulation of chromosomal aberrations and tyrosine kinase inhibitor-resistant BCR-ABL1 mutants. JAK2(V617F) and FLT3(ITD)-positive polycythemia vera cells and acute myeloid leukemia cells also produce ROS via MRC-cIII. In the present study, inhibition of Rac2 by genetic deletion or a small-molecule inhibitor and down-regulation of mitochondrial ROS by disruption of MRC-cIII, expression of mitochondria-targeted catalase, or addition of ROS-scavenging mitochondria-targeted peptide aptamer reduced genomic instability. We postulate that the Rac2-MRC-cIII pathway triggers ROS-mediated genomic instability in LSCs and primitive LPCs, which could be targeted to prevent the relapse and malignant progression of CML.
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MESH Headings
- Animals
- Catalase/metabolism
- DNA Damage
- DNA, Neoplasm/genetics
- DNA, Neoplasm/metabolism
- Disease Progression
- Electron Transport
- Electron Transport Complex III/metabolism
- Fusion Proteins, bcr-abl/genetics
- Genomic Instability
- Humans
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Leukemia, Myeloid, Chronic-Phase/pathology
- Membrane Potential, Mitochondrial
- Methacrylates/pharmacology
- Mice
- Neoplasm Proteins/antagonists & inhibitors
- Neoplasm Proteins/genetics
- Neoplasm Proteins/physiology
- Neoplastic Stem Cells/drug effects
- Neoplastic Stem Cells/metabolism
- Polycythemia Vera/metabolism
- Polycythemia Vera/pathology
- Reactive Oxygen Species/metabolism
- Recombinant Fusion Proteins/antagonists & inhibitors
- Recombinant Fusion Proteins/physiology
- Superoxide Dismutase/metabolism
- Thiazoles/pharmacology
- rac GTP-Binding Proteins/antagonists & inhibitors
- rac GTP-Binding Proteins/genetics
- rac GTP-Binding Proteins/physiology
- RAC2 GTP-Binding Protein
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Affiliation(s)
- Margaret Nieborowska-Skorska
- Department of Microbiology and Immunology, Temple University School of Medicine, 3400 N. Broad Street, Philadelphia, PA 19140, USA
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Aoyagi M, Kamoi T, Kato M, Sasako H, Tsuge N, Imai S. Structure and bioactivity of thiosulfinates resulting from suppression of lachrymatory factor synthase in onion. J Agric Food Chem 2011; 59:10893-10900. [PMID: 21905712 DOI: 10.1021/jf202446q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In normal onion (Allium cepa), trans-S-1-propenyl-L-cysteine sulfoxide is transformed via 1-propenesulfenic acid into propanethial S-oxide, a lachrymatory factor, through successive reactions catalyzed by alliinase and lachrymatory factor synthase (LFS). A recent report showed that suppression of the LFS activity caused a dramatic increase in thiosulfinates previously reported as "zwiebelane isomers". After purification by recycle high-performance liquid chromatography and subsequent analyses, we established the planar structure of the putative "zwiebelane isomers" as S-3,4-dimethyl-5-hydroxythiolane-2-yl 1-propenethiosulfinate, in which two of the three molecules of 1-propenesulfenic acid involved in the formation gave the thiolane backbone, and the third molecule gave the thiosulfinate structure. Of at least three stereoisomers observed, one in the (2'R,3'R,4'R,5'R)-configuration was collected as an isolated fraction, and the other isomers were collected as a combined fraction because spontaneous tautomerization prevented further purification. Both fractions showed inhibitory activities against cyclooxygenase-1 and α-glucosidase in vitro.
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Affiliation(s)
- Morihiro Aoyagi
- Somatech Center, House Foods Corporation, 1-4 Takanodai, Yotsukaido, Chiba, 284-0033, Japan.
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Sakamoto H, Tsukaguchi T, Hiroshima S, Kodama T, Kobayashi T, Fukami TA, Oikawa N, Tsukuda T, Ishii N, Aoki Y. CH5424802, a selective ALK inhibitor capable of blocking the resistant gatekeeper mutant. Cancer Cell 2011; 19:679-90. [PMID: 21575866 DOI: 10.1016/j.ccr.2011.04.004] [Citation(s) in RCA: 475] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 02/23/2011] [Accepted: 04/02/2011] [Indexed: 12/23/2022]
Abstract
Anaplastic lymphoma kinase (ALK) is a tyrosine kinase that is constitutively activated in certain cancers, following gene alterations such as chromosomal translocation, amplification, or point mutation. Here, we identified CH5424802, a potent, selective, and orally available ALK inhibitor with a unique chemical scaffold, showing preferential antitumor activity against cancers with gene alterations of ALK, such as nonsmall cell lung cancer (NSCLC) cells expressing EML4-ALK fusion and anaplastic large-cell lymphoma (ALCL) cells expressing NPM-ALK fusion in vitro and in vivo. CH5424802 inhibited ALK L1196M, which corresponds to the gatekeeper mutation conferring common resistance to kinase inhibitors, and blocked EML4-ALK L1196M-driven cell growth. Our results support the potential for clinical evaluation of CH5424802 for the treatment of patients with ALK-driven tumors.
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Affiliation(s)
- Hiroshi Sakamoto
- Kamakura Research Laboratories, Chugai Pharmaceutical Co., Ltd., 200 Kajiwara, Kamakura, Kanagawa 247-8530, Japan.
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Abstract
INTRODUCTIONFluorescein-assisted light inactivation (FALI) is a powerful method for studying acute loss of protein function, even if the corresponding mutations lead to early lethality. In this protocol, FALI is mediated by the membrane-permeable FlAsH (4′,5′-bis(1,3,2-dithioarsolan-2-yl)fluorescein) compound that binds with high specificity to the genetically encoded tetracysteine tag and thus allows the inactivation of protein function in vivo with exquisite spatial (<40 Å) and temporal (<30 sec) resolution. It also enables the analysis of kinetically distinct processes such as synaptic vesicle exocytosis and endocytosis. This protocol describes efficient inactivation of a protein using FlAsH-FALI at the neuromuscular junction (NMJ) of third-instar larvae. Note that FlAsH-FALI in other tissues is also theoretically possible with minor adaptations to the protocol described here. We explain controls for positional effects, for unspecific FlAsH binding to endogenous proteins, and for phototoxicity. Following FlAsH-FALI, protein function can be studied using a number of secondary assays, including electrophysiology, immunohistochemistry, and electron microscopy or FM1-43 labeling of synaptic vesicle pools.
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Srinivasan B, Johnson TE, Xing C. Chalcone-based inhibitors against hypoxia-inducible factor 1--structure activity relationship studies. Bioorg Med Chem Lett 2010; 21:555-7. [PMID: 21112783 DOI: 10.1016/j.bmcl.2010.10.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 10/12/2010] [Accepted: 10/14/2010] [Indexed: 11/17/2022]
Abstract
Many tumor tissues are under hypoxic conditions. Activating hypoxia-inducible factor 1 (HIF-1), a transcription factor, is a major mechanism for tumor cells to survive and even to evade other tissues. Therefore inhibiting HIF-1 is a potential strategy to help improve cancer treatment. Chalcone is a promising template to develop HIF-1 inhibitor because quite a few of chalcone-based compounds reveal moderate HIF-1 inhibitory activity and many chalcone-based compounds demonstrate promising anticancer activities in various animal models. However, there are no reports about the structure-activity relationship of chalcone compounds with respect to HIF-1 inhibition. This study reports the HIF-1 inhibitory activities of a panel of chalcones, identifies a few lead candidates of single-digit micromolar potency, and determines important structural modifications.
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Affiliation(s)
- Balasubramanian Srinivasan
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, 308 Harvard St. SE, Minneapolis MN 55455, United States
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12
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Oh K, Joo KM, Jung YS, Lee J, Kang H, Lee HY, Lee DS. A receptor-independent, cell-based JAK activation assay for screening for JAK3-specific inhibitors. J Immunol Methods 2010; 354:45-52. [PMID: 20138049 DOI: 10.1016/j.jim.2010.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Revised: 01/22/2010] [Accepted: 01/26/2010] [Indexed: 10/19/2022]
Abstract
New immunosuppressive compounds with less systemic toxicity that could replace calcineurin inhibitors are urgently needed. For identification of specific inhibitors of JAK3, a potential new drug target, from large chemical libraries we developed a cell-based screening system. TEL-JAK fusion proteins composed of an oligomerization domain of TEL and kinase and/or pseudokinase domains of JAKs provided constitutive activation of JAKs without receiving a signal from the cytokine receptors. These fusion proteins also induced STAT5b phosphorylation in the absence of cytokine receptors. Both the kinase and pseudokinase domains of JAKs were required for full activation of the JAKs, and four copies of STAT5 response elements provided the greatest luciferase activity. The sensitivity and specificity of the system was evaluated using specific JAK3, JAK2, or MEK inhibitors. Thus, we generated a receptor-independent, cell-based selective screening system for specific JAK3 inhibitors, which is easily convertible to a high-throughput screening platform.
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Affiliation(s)
- Keunhee Oh
- Laboratory of Immunology, Department of Anatomy, Seoul National University College of Medicine, Republic of Korea
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Lee MS, Choi HS, Kwon SH, Morita K, Her S. Identification of the functional domain of glucocorticoid receptor involved in RU486 antagonism. J Steroid Biochem Mol Biol 2009; 117:67-73. [PMID: 19635558 DOI: 10.1016/j.jsbmb.2009.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2008] [Revised: 07/16/2009] [Accepted: 07/17/2009] [Indexed: 10/20/2022]
Abstract
Mifepristone, also known as RU486, is a potent glucocorticoid receptor (GR) antagonist that inhibits GR-mediated transactivation. As an alternative to existing antidepressants, RU486 has been shown to rapidly reverse psychotic depression, most likely by blocking GR. Although a number of studies have demonstrated RU486-induced GR antagonism, the precise mechanism of action still remains unclear. To identify the GR domain involved in RU486-induced suppression, GR transactivation and nuclear translocation were examined using cells transfected with human GR (hGR), Guyanese squirrel monkey GR (gsmGR), and GR chimeras into COS-1 cells. RU486 showed a much more potent suppressive effect in gsmGR-expressing cells versus hGR-expressing cells, without significant cortisol- or RU486-induced changes in nuclear translocation. A GR chimera containing the gsmGR AF1 domain (amino acids 132-428) showed a marked decrease in luciferase activity, suggesting that this domain plays an important role in RU486-induced GR antagonism. Furthermore, fluorescence recovery after photobleaching (FRAP) analysis indicated that, in the presence of RU486, gsmGR AF1 domain contributes to GR mobility in living COS-1 cells. Taken together, these results demonstrate, for the first time, that the antagonistic effects of RU486 on GR transactivation involve a specific GR domain.
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Affiliation(s)
- Mi-Sook Lee
- Division of Bio-Imaging, Chuncheon Center, Korea Basic Science Institute, Chuncheon 200-701, Republic of Korea
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14
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Newman AH, Grundt P, Cyriac G, Deschamps JR, Taylor M, Kumar R, Ho D, Luedtke RR. N-(4-(4-(2,3-dichloro- or 2-methoxyphenyl)piperazin-1-yl)butyl)heterobiarylcarboxamides with functionalized linking chains as high affinity and enantioselective D3 receptor antagonists. J Med Chem 2009; 52:2559-70. [PMID: 19331412 PMCID: PMC2760932 DOI: 10.1021/jm900095y] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present report, the D3 receptor pharmacophore is modified in the 2,3-diCl- and 2-OCH(3)-phenylpiperazine class of compounds with the goal to improve D3 receptor affinity and selectivity. This extension of structure-activity relationships (SAR) has resulted in the identification of the first enantioselective D3 antagonists (R- and S-22) to be reported, wherein enantioselectivity is more pronounced at D3 than at D2, and that a binding region on the second extracellular loop (E2) may play a role in both enantioselectivity and D3 receptor selectivity. Moreover, we have discovered some of the most D3-selective compounds reported to date that show high affinity (K(i) = 1 nM) for D3 and approximately 400-fold selectivity over the D2 receptor subtype. Several of these analogues showed exquisite selectivity for D3 receptors over >60 other receptors, further underscoring their value as in vivo research tools. These lead compounds also have appropriate physical characteristics for in vivo exploration and therefore will be useful in determining how intrinsic activity at D3 receptors tested in vitro is related to behaviors in animal models of addiction and other neuropsychiatric disorders.
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Affiliation(s)
- Amy Hauck Newman
- Medicinal Chemistry Section, National Institute on Drug AbuseIntramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, USA.
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15
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N'Diaye EN, Kajihara KK, Hsieh I, Morisaki H, Debnath J, Brown EJ. PLIC proteins or ubiquilins regulate autophagy-dependent cell survival during nutrient starvation. EMBO Rep 2009; 10:173-9. [PMID: 19148225 PMCID: PMC2637314 DOI: 10.1038/embor.2008.238] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 11/10/2008] [Accepted: 11/11/2008] [Indexed: 11/08/2022] Open
Abstract
Ubiquilins (UBQLNs) are adaptor proteins thought to deliver ubiquitinated substrates to proteasomes. Here, we show a role for UBQLN in autophagy: enforced expression of UBQLN protects cells from starvation-induced death, whereas depletion of UBQLN renders cells more susceptible. The UBQLN protective effect requires the autophagy-related genes ATG5 and ATG7, two essential components of autophagy. The ubiquitin-associated domain of UBQLN mediates both its association with autophagosomes and its protective effect against starvation. Depletion of UBQLN delays the delivery of autophagosomes to lysosomes. This study identifies a new role for UBQLN in regulating the maturation of autophagy, expanding the involvement of ubiquitin-related proteins in this process.
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Affiliation(s)
- Elsa-Noah N'Diaye
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
| | - Kimberly K Kajihara
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
| | - Ivy Hsieh
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
| | - Hiroshi Morisaki
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
| | - Jayanta Debnath
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
| | - Eric J Brown
- Department of Microbial Pathogenesis, Genentech, 1 DNA Way, South San Francisco, California 94080, USA
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16
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Mitsuhashi S, Shima H, Li Y, Tanuma N, Okamoto T, Kikuchi K, Ubukata M. Tautomycetin suppresses the TNFalpha/NF-kappaB pathway via inhibition of IKK activation. Int J Oncol 2008; 33:1027-1035. [PMID: 18949366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
TNFalpha activated NF-kappaB and associated regulatory factors including IKK are strongly implicated in a variety of hematological and solid tumor malignancies. We show that tautomycetin (TC) specifically inhibits activation of NF-kappaB among the three TNFalpha effectors (NF-kappaB, JNK and caspase). TC inhibited T-loop phosphorylation of IKKalpha and IKKbeta, thereby preventing degradation of the NF-kappaB inhibitor, IkappaBalpha. Co-immunoprecipitation experiments revealed that the catalytic subunit of PP1 (PP1C) was involved in the IKK complex. Pull-down analysis using recombinant GST-TNFalpha, showed that PP1C was recruited to TNFR1 together with IKK complex, RIP and TAK1 upon stimulus. These results suggest that the PP1 positively regulates the TNFalpha-induced NF-kappaB pathway at the level of IKK activation. Thus, TC might be used therapeutically to suppress the TNFalpha/NF-kappaB pathway.
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Affiliation(s)
- Shinya Mitsuhashi
- Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-ku, Sapporo 060-0815, Japan
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17
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Erickson MG, Ulijasz AT, Weisblum B. Screening for compounds that affect the interaction between bacterial two-component signal transduction response regulator protein and cognate promoter DNA. Methods Mol Med 2008; 142:215-222. [PMID: 18437317 DOI: 10.1007/978-1-59745-246-5_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Bacterial signal transduction systems can be used as drug targets. The signal transduction targets fall into two groups--sensor kinases and response regulators. Previously reported studies describe hits that were thought to inactivate sensor kinases but on closer examination were found to act elsewhere instead; a possible reason for this is that full-length sensor kinases are integral membrane proteins whose activity might reflect interaction with the cell membrane or with membrane components. We describe a model system that instead is based on the interaction between a test compound and a response regulator in a homogeneous phase reaction. In this system, response regulator-DNA complex formation and its inhibition by a test compound are measured by fluorescence polarization. The model system should be readily adaptable to drug discovery based on other bacterial two-component s transduction systems.
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Affiliation(s)
- Matthew G Erickson
- Department of Pharmacology, University of Wisconsin Medical School, Madison, WI, USA
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18
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Abstract
On target cells, interleukin-6 (IL-6) interacts with its receptor complex consisting of the membrane-bound IL-6 receptor (IL-6R) and the signal transducing protein gp130. IL-6R can exist as a soluble protein (sIL-6R), which binds the ligand IL-6. This soluble complex can bind to gp130 on cells that lack the membrane-bound IL-6R and initiate signaling. This process is named transsignaling. The significance of transsignaling via sIL-6R is underlined by different publications and exceeds very probably the significance of the membrane-bound IL-6R. It is the general assumption that sIL-6R acts as an agonist in combination with IL-6 resulting in an enhancement of the IL-6 effects. In this article, we suppose 'non-agonistic' properties. There are several publications that give reasons to speculate that sIL-6R (a) has IL-6-antagonistic effects, (b) has orphan properties and (c) interacts with yet unknown binding partners different from IL-6. Knowledge about additional properties of sIL-6R will enlarge the biologic understanding of this molecule and might give an explanation for the sometimes contrasting effects of the cytokine IL-6.
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Affiliation(s)
- Heike Knüpfer
- Institute of Clinical Pharmacology, University of Leipzig, Härtelstrasse 16-18, Leipzig, Germany.
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19
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Wyler E, Kaminska M, Coïc YM, Baleux F, Véron M, Agou F. Inhibition of NF-kappaB activation with designed ankyrin-repeat proteins targeting the ubiquitin-binding/oligomerization domain of NEMO. Protein Sci 2007; 16:2013-22. [PMID: 17766391 PMCID: PMC2206981 DOI: 10.1110/ps.072924907] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The link between the NF-kappaB signal transduction pathway and cancer is now well established. Inhibiting this pathway is therefore a promising approach in the treatment of certain cancers through a pro-apoptotic effect in malignant cells. Owing to its central role in the pathway, the IkappaB kinase (IKK) complex is a privileged target for designing inhibitors. Previously, we showed that oligomerization of NEMO is necessary for IKK activation and defined a minimal oligomerization domain (CC2-LZ) for NEMO, and we developed NEMO peptides inhibiting NF-kappaB activation at the level of the IKK complex. To improve the low-affinity inhibitors, we used ribosome display to select small and stable proteins with high affinity against the individual CC2-LZ because the entire NEMO protein is poorly soluble. Several binders with affinities in the low nanomolar range were obtained. When expressed in human cells, some of the selected molecules, despite their partial degradation, inhibited TNF-alpha-mediated NF-kappaB activation while having no effect on the basal activity. Controls with a naive library member or null plasmid had no effect. Furthermore, we could show that this NF-kappaB inhibition occurs through a specific interaction between the binders and the endogenous NEMO, resulting in decreased IKK activation. These results indicate that in vitro selections with the NEMO subdomain alone as a target may be sufficient to lead to interesting compounds that are able to inhibit NF-kappaB activation.
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Affiliation(s)
- Emanuel Wyler
- Unité Régulation Enzymatique des Activités Cellulaires, Institut Pasteur, CNRS URA 2185, 75724 Paris Cedex 15, France
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20
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Yuan C, Zins EJ, Clark AF, Huang AJW. Suppression of keratoepithelin and myocilin by small interfering RNAs (siRNA) in vitro. Mol Vis 2007; 13:2083-2095. [PMID: 18079684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Accepted: 10/24/2007] [Indexed: 05/25/2023] Open
Abstract
PURPOSE Mutations of keratoepithelin (KE) and myocilin (MYOC) have been linked to certain types of inherited corneal stromal dystrophy and open-angle glaucoma, respectively. We investigated the potential use of small interfering RNAs (siRNAs) to suppress the expression of KE and MYOC and the related cytotoxicity of mutant myocilins in vitro. METHODS cDNAs of the human keratoepithelin (KE) gene and myocilin (MYOC) gene were amplified by polymerase chain reaction and subcloned into pEGFP-N1 to construct respective plasmids, KEpEGFP and MYOCpEGFP, to produce fluorescence-generating fusion proteins. Short hairpin RNAs (shRNAs) were generated from an RNA polymerase III promoter-driven vector (pH1-RNA). Transformed HEK293 and trabecular meshwork (TM) cells were cotransfected via liposomes with either KEpEGFP or MYOCpEGFP and respective shRNA-generating plasmids to evaluate the suppression efficacy of shRNAs. Suppression of KE-EGFP fusion protein by KE-specific shRNAs was evaluated by fluorescence microscopy and western blotting. Suppression of MYOC-EGFP fusion protein by myocilin-specific shRNAs was quantified with UN-SCAN-IT software on digitized protein bands of western blots. The cellular stress response of TM cells induced by misfolded mutant myocilins was evaluated with a BiP promoter-driven luciferase reporter assay. RESULTS One shRNA (targeting the coding sequence starting at 1,528 bp of KE) reduced the expression of KE-EGFP in HEK293 cells approximately by 50% whereas the other shRNA (targeting the 3'-UTR region of KE) suppressed more than 80% of the expression of fusion protein. Cotransfection of MYOCpEGFP and various shRNA-generating plasmids targeting different regions of MYOC (containing amino acid residues R76, E352, K423, or N480 associated with inherited glaucoma) showed effective reduction of MYOC-EGFP fusion protein, ranged from 78% to 90% on average. The activation of the BiP gene (a cellular stress response induced by mutant myocilins) in transformed TM cells was significantly reduced when mutant myocilin proteins were suppressed by myocilin-specific shRNAs. CONCLUSIONS KE-specific or MYOC-specific shRNAs effectively suppressed the expression of recombinant KE or myocilin proteins and the related cytotoxicity of mutant myocilins in vitro. RNA interference may have future therapeutic implications in suppressing these genes.
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Affiliation(s)
- Ching Yuan
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN, USA
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21
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Radhakrishnan SK, Bhat UG, Hughes DE, Wang IC, Costa RH, Gartel AL. Identification of a chemical inhibitor of the oncogenic transcription factor forkhead box M1. Cancer Res 2007; 66:9731-5. [PMID: 17018632 DOI: 10.1158/0008-5472.can-06-1576] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The oncogenic transcription factor forkhead box M1 (FoxM1) is overexpressed in a number of different carcinomas, whereas its expression is turned off in terminally differentiated cells. For this reason, FoxM1 is an attractive target for therapeutic intervention in cancer treatment. As a first step toward realizing this goal, in this study, using a high-throughput, cell-based assay system, we screened for and isolated the antibiotic thiazole compound Siomycin A as an inhibitor of FoxM1. Interestingly, we observed that Siomycin A was able to down-regulate the transcriptional activity as well as the protein and mRNA abundance of FoxM1. Consequently, we found that the downstream target genes of FoxM1, such as Cdc25B, Survivin, and CENPB, were repressed. Also, we observed that consistent with earlier reports of FoxM1 inhibition, Siomycin A was able to reduce anchorage-independent growth of cells in soft agar. Furthermore, we found that Siomycin A was able to induce apoptosis selectively in transformed but not normal cells of the same origin. Taken together, our data suggest that FoxM1 inhibitor Siomycin A could represent a useful starting point for the development of anticancer therapeutics.
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22
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Mita R, Coles JE, Glubrecht DD, Sung R, Sun X, Godbout R. B-FABP-expressing radial glial cells: the malignant glioma cell of origin? Neoplasia 2007; 9:734-44. [PMID: 17898869 PMCID: PMC1993858 DOI: 10.1593/neo.07439] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2007] [Revised: 07/04/2007] [Accepted: 07/06/2007] [Indexed: 11/18/2022] Open
Abstract
Brain fatty acid-binding protein (B-FABP) is normally expressed in radial glial cells, where it plays a role in the establishment of the radial glial fiber network required for neuronal migration. B-FABP is also expressed in astrocytoma tumors and in some malignant glioma cell lines. To address the role of B-FABP in malignant glioma, we have studied the growth properties of clonal populations of malignant glioma cells modified for B-FABP expression. Here, we demonstrate that expression of B-FABP in B-FABP-negative malignant glioma cells is accompanied by the appearance of radial glial-like properties, such as increased migration and extended bipolar cell processes, as well as reduced transformation. Conversely, B-FABP depletion in B-FABP-positive malignant glioma cells results in decreased migration, reduction in cell processes, and a more transformed phenotype. Moreover, expression of B-FABP in astrocytomas is associated with regions of tumor infiltration and recurrence. Rather than being a direct manifestation of the tumorigenic process, we propose that the ability of high-grade astrocytoma cells to migrate long distances from the primary tumor reflects properties associated with their cell of origin. Thus, targeting B-FABP-expressing cells may make a significant impact on the treatment of these tumors.
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Affiliation(s)
- Raja Mita
- Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
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23
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Scott-Ward TS, Cai Z, Dawson ES, Doherty A, Carina Da Paula A, Davidson H, Porteous DJ, Wainwright BJ, Amaral MD, Sheppard DN, Boyd AC. Chimeric constructs endow the human CFTR Cl- channel with the gating behavior of murine CFTR. Proc Natl Acad Sci U S A 2007; 104:16365-70. [PMID: 17913891 PMCID: PMC2042212 DOI: 10.1073/pnas.0701562104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl(-) channel gated by ATP-driven nucleotide-binding domain (NBD) dimerization. Here we exploit species differences between human and murine CFTR to investigate CFTR channel gating. Using homologous recombination, we constructed human-murine CFTR (hmCFTR) chimeras with sequences from NBD1, NBD2, or the regulatory domain (RD) of human CFTR replaced by the equivalent regions of murine CFTR. The gating behavior of hmRD and human CFTR were indistinguishable, whereas hmNBD1 and hmNBD2 had subtle effects on channel gating, prolonging both burst duration and interburst interval. By contrast, hmNBD1+2, containing both NBDs of murine CFTR, reproduced the gating behavior of the subconductance state of murine CFTR, which has dramatically prolonged channel openings. The CFTR potentiator pyrophosphate (PP(i)) enhanced human, hmRD, and hmNBD1 CFTR Cl(-) currents, but not those of hmNBD2, hmNBD1+2, and murine CFTR. By analyzing the rate-equilibrium free-energy relationships of chimeric channels, we obtained snapshots of the conformation of the NBDs during ATP-driven dimerization. Our data demonstrate that the conformation of NBD1 changes before that of NBD2 during channel opening. This finding suggests that NBD dimerization does not proceed by a symmetric tweezer-like motion, but instead in an asymmetric fashion led by NBD1. We conclude that the NBDs of murine CFTR determine the unique gating behavior of its subconductance state, whereas NBD2 controls channel potentiation by PP(i).
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Affiliation(s)
- Toby S. Scott-Ward
- Department of Physiology and Pharmacology, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom
| | - Zhiwei Cai
- Department of Physiology and Pharmacology, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom
| | - Elizabeth S. Dawson
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Ann Doherty
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Ana Carina Da Paula
- Centre of Human Genetics, National Institute of Health, Avenue Padre Cruz, 1649-016 Lisbon, Portugal; and
| | - Heather Davidson
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - David J. Porteous
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Brandon J. Wainwright
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Margarida D. Amaral
- Centre of Human Genetics, National Institute of Health, Avenue Padre Cruz, 1649-016 Lisbon, Portugal; and
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa, Campo Grande-C8, 1749-016 Lisbon, Portugal
| | - David N. Sheppard
- Department of Physiology and Pharmacology, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, United Kingdom
- To whom correspondence should be addressed. E-mail:
| | - A. Christopher Boyd
- Medical Genetics Section, University of Edinburgh, Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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Zhang XH, Guo XN, Zhong L, Luo XM, Jiang HL, Lin LP, Ding J. Establishment of the active catalytic domain of human PDGFRβ tyrosine kinase-based ELISA assay for inhibitor screening. Biochim Biophys Acta Gen Subj 2007; 1770:1490-7. [PMID: 17719179 DOI: 10.1016/j.bbagen.2007.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2007] [Revised: 06/26/2007] [Accepted: 06/28/2007] [Indexed: 10/23/2022]
Abstract
Tyrosine kinases are emerging as frequent targets of primary oncogenic events and therefore represent an optimal focus of therapeutic intervention. In an effort towards therapeutic PDGFR inactivation, we expressed the catalytic domain of PDGFRbeta as a soluble active kinase using Bac-to-Bac expression system, and studied the correlations between PDGFRbeta activity and enzyme concentration, ATP concentration, substrate concentration and divalent cation type. And a convenient, effective and non-radioactive ELISA screening model is then established for identification of the potential inhibitors targeting PDGFRbeta kinase. Of 500 RTK target-based compounds, TKI-30 was identified as a small molecule potential inhibitor of PDGFRbeta (IC(50)=0.34 microM). Further studies indicated that TKI-30 blocked PDGF-BB-induced autophosphorylation of PDGFRbeta in a dose-dependent manner in Swiss 3T3 cells and human umbilical vein smooth muscle cells (HUVSMCs). Moreover, it dose-dependently suppressed the PDGF-BB-induced proliferation in HUVSMCs and tube formation of HUVEC. Our data collectively indicated that PDGFRbeta-based ELISA assay is a new method available for screening inhibitors targeting PDGFRbeta kinase and TKI-30 is a potential novel anti-cancer agent worthy of being further investigated.
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Affiliation(s)
- Xiu-Hua Zhang
- Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, 555 Zu Chong Zhi Road, Zhangjiang Hitec Park, Shanghai, 201203 PR China
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25
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Umetani M, Domoto H, Gormley AK, Yuhanna IS, Cummins CL, Javitt NB, Korach KS, Shaul PW, Mangelsdorf DJ. 27-Hydroxycholesterol is an endogenous SERM that inhibits the cardiovascular effects of estrogen. Nat Med 2007; 13:1185-92. [PMID: 17873880 DOI: 10.1038/nm1641] [Citation(s) in RCA: 290] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Accepted: 08/08/2007] [Indexed: 01/18/2023]
Abstract
The cardioprotective effects of estrogen are mediated by receptors expressed in vascular cells. Here we show that 27-hydroxycholesterol (27HC), an abundant cholesterol metabolite that is elevated with hypercholesterolemia and found in atherosclerotic lesions, is a competitive antagonist of estrogen receptor action in the vasculature. 27HC inhibited both the transcription-mediated and the non-transcription-mediated estrogen-dependent production of nitric oxide by vascular cells, resulting in reduced estrogen-induced vasorelaxation of rat aorta. Furthermore, increasing 27HC levels in mice by diet-induced hypercholesterolemia, pharmacologic administration or genetic manipulation (by knocking out the gene encoding the catabolic enzyme CYP7B1) decreased estrogen-dependent expression of vascular nitric oxide synthase and repressed carotid artery reendothelialization. As well as antiestrogenic effects, there were proestrogenic actions of 27HC that were cell-type specific, indicating that 27HC functions as an endogenous selective estrogen receptor modulator (SERM). Taken together, these studies point to 27HC as a contributing factor in the loss of estrogen protection from vascular disease.
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MESH Headings
- Animals
- Aorta, Thoracic/drug effects
- Binding, Competitive/drug effects
- Cardiotonic Agents/antagonists & inhibitors
- Cardiotonic Agents/metabolism
- Cardiotonic Agents/pharmacology
- Cell Culture Techniques
- Cell Line
- Cells, Cultured
- Cholesterol, Dietary/administration & dosage
- DNA, Complementary
- Dose-Response Relationship, Drug
- Drug Administration Schedule
- Estrogens/metabolism
- Estrogens/pharmacology
- Female
- Glutathione Transferase/metabolism
- Humans
- Hydroxycholesterols/administration & dosage
- Hydroxycholesterols/blood
- Hydroxycholesterols/pharmacology
- Inhibitory Concentration 50
- Injections, Subcutaneous
- Kidney/cytology
- Kinetics
- Male
- Mice
- Mice, Knockout
- Nitric Oxide/antagonists & inhibitors
- Nitric Oxide Synthase Type II/antagonists & inhibitors
- Nitric Oxide Synthase Type III
- RNA, Messenger/metabolism
- Receptors, Estrogen/antagonists & inhibitors
- Receptors, Estrogen/genetics
- Recombinant Fusion Proteins/antagonists & inhibitors
- Selective Estrogen Receptor Modulators/administration & dosage
- Selective Estrogen Receptor Modulators/blood
- Selective Estrogen Receptor Modulators/pharmacology
- Vasodilation/drug effects
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Affiliation(s)
- Michihisa Umetani
- Department of Pharmacology and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, Texas 75390-9050, USA
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26
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Jensen AA, Zlotos DP, Liljefors T. Pharmacological characteristics and binding modes of caracurine V analogues and related compounds at the neuronal alpha7 nicotinic acetylcholine receptor. J Med Chem 2007; 50:4616-29. [PMID: 17722904 DOI: 10.1021/jm070574f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pharmacological properties of bisquaternary caracurine V, iso-caracurine V, and pyrazino[1,2-a;4,5-a']diindole analogues and of the neuromuscular blocking agents alcuronium and toxiferine I have been characterized at numerous ligand-gated ion channels. Several of the analogues are potent antagonists of the homomeric alpha7 nicotinic acetylcholine receptor (nAChR), displaying nanomolar binding affinities and inhibiting acetylcholine-evoked signaling through the receptor in a competitive manner. In contrast, they do not display activities at heteromeric neuronal nAChRs and only exhibit weak antagonistic activities at the related 5-HT3A serotonin receptor. In a mutagenesis study, five selected analogues have been demonstrated to bind to the orthosteric site of the alpha7 nAChR. The binding site of the compounds overlaps with that of the standard alpha7 antagonist methyllycaconitine, the binding of them being centered in a cation-pi interaction between the quaternary nitrogen atom of the ligand and the Trp149 residue in the receptor, with additional key contributions from other aromatic receptor residues such as Tyr188, Tyr195, and Trp55.
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Affiliation(s)
- Anders A Jensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
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27
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Abstract
Porphyromonas gingivalis has been implicated as an important pathogen in the development of periodontitis. Hemagglutinins have been identified as important adhesion molecules, allowing Porphyromonas gingivalis to adhere to gingival tissue cells, and to attach and lyse erythrocytes in order to uptake Fe ions as essential nutrition. One hemagglutinin, hemagglutinin A (HagA), has been molecularly cloned via functional screening for hemagglutinating activity. We previously cloned the gene encoding the 200-kDa cell-surface antigenic protein that was reacted by sera from periodontitis patients and was identified as a truncated protein of HagA by nucleotide sequence analysis. We further subcloned the gene encoding an 122-kDa protein (122k-HagA) which is a fusion protein composed of an 80-kDa truncated HagA containing the functional motif PVQNLT and a 42-kDa maltose binding protein. Passive immunization against infectious pathogens by specific antibodies produced from hen egg yolk antibody (IgY) has been extensively developed. In the present study, to develop passive immunotherapy against periodontal disease, we purified the recombinant 122k-HagA and used this to immunize hens and produce IgY. The purified IgY reacted with the recombinant 122k-HagA and the synthetic peptide containing PVQNLT, and inhibited hemagglutinating activity of Porphyromonas gingivalis. Thus, the novel IgY may be useful in the development of a passive immunization against periodontal diseases caused by P. gingivalis infection.
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Affiliation(s)
- Akihide Tezuka
- Department of Biochemistry and Molecular Biology, Nihon University School of Dentistry at Matsudo, Chiba, Japan
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28
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Abstract
Basic fibroblast growth factor (bFGF) is a potent angiogenic molecule, but its therapeutic use is limited by mitogenic effects on multiple cell types. To specifically activate FGF signaling in endothelial cells, a chimeric FGF receptor was generated that contained a modified FK506 drug-binding domain (F36V) fused to the FGF receptor-1 (FGFR1) cytoplasmic domain. Human umbilical vein endothelial cells (HUVECs) and human microvascular endothelial cells were retrovirally transduced with this chimeric receptor, and the effects of administering synthetic receptor-dimerizing ligands were studied. As expected, both control and transduced cells proliferated in response to bFGF treatment; however, only transduced endothelial cells exhibited dose-dependent proliferative responses to dimerizer treatment. Dimerizer-induced proliferation was MEK-dependent and was accompanied by MAP kinase phosphorylation, indicating that the chimeric receptor utilizes signaling pathways similar to endogenous FGFR1. Although bFGF stimulated wound re-epithelialization in HUVECs (which natively express FGFR1 and FGFR4), chemical dimerization of FGFR1 did not; this suggests FGFR4 may control migration in these cells. The ability to selectively activate receptor subtypes should facilitate the study of signaling pathways in vitro and in vivo beyond what can be accomplished with nonselective natural ligands, and it may eventually permit stimulation of graft cell angiogenesis without driving overgrowth of host cells.
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Affiliation(s)
- Marilyn B Nourse
- Department of Bioengineering, University of Washington, Seattle, WA 98109, USA
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29
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Abstract
Due to the pivotal roles that protein-protein interactions play in a plethora of biological processes, the design of therapeutic agents targeting these interactions has become an attractive and important area of research. The development of such agents is faced with a variety of challenges. Nevertheless, considerable progress has been made in the design of proteomimetics capable of disrupting protein-protein interactions. Those inhibitors based on molecular scaffold designs hold considerable interest because of the ease of variation in regard to their displayed functionality. In particular, protein surface mimetics, alpha-helical mimetics, beta-sheet/beta-strand mimetics, as well as beta-turn mimetics have successfully modulated protein-protein interactions involved in such diseases as cancer and HIV. In this review, current progress in the development of molecular scaffolds designed for the disruption of protein-protein interactions will be discussed with an emphasis on those active against biological targets.
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Affiliation(s)
- Stefan J Hershberger
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907, USA
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30
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Abstract
Protein-protein interactions play crucial roles in a number of biological processes, and, as such, their disruption is becoming an area of intense research. Despite the many challenges associated with the development of protein-protein interaction inhibitors, such as the large and relatively featureless interfacial areas involved, there has been considerable success in recent years. Importantly, through the existence of protein "hot spots", some of this success takes the form of small molecule inhibitors that have been identified from a variety of screening techniques.
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Affiliation(s)
- Steven Fletcher
- Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA
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31
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Affiliation(s)
- Kryn Stankunas
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Gerald R. Crabtree
- Departments of Pathology and Developmental Biology, Stanford University School of Medicine and Howard Hughes Medical Institute, Stanford, CA 94305
- To whom correspondence should be addressed at:
Departments of Developmental Biology and Pathology, B211 Beckman Center, 279 Campus Drive, Stanford University School of Medicine, Stanford, CA 94305-5323. E-mail:
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32
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Mal TK, Takahata S, Ki S, Zheng L, Kokubo T, Ikura M. Functional silencing of TATA-binding protein (TBP) by a covalent linkage of the N-terminal domain of TBP-associated factor 1. J Biol Chem 2007; 282:22228-38. [PMID: 17553784 DOI: 10.1074/jbc.m702988200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
General transcription factor TFIID is comprised of TATA-binding protein (TBP) and TBP-associated factors (TAFs), together playing critical roles in regulation of transcription initiation. The TAF N-terminal domain (TAND) of yeast TAF1 containing two subdomains, TAND1 (residues 10-37) and TAND2 (residues 46-71), is sufficient to interact with TBP and suppress the TATA binding activity of TBP. However, the detailed structural analysis of the complex between yeast TBP and TAND12 (residues 6-71) was hindered by its poor solubility and stability in solution. Here we report a molecular engineering approach where the N terminus of TBP is fused to the C terminus of TAND12 via linkers of various lengths containing (GGGS)(n) sequence, (n = 1, 2, 3). The length of the linker within the TAND12-TBP fusion has a significant effect on solubility and stability (SAS). The construct with (GGGS)(3) linker produces the best quality single-quantum-coherence (HSQC) NMR spectrum with markedly improved SAS. In parallel to these observations, the TAND12-TBP fusion exhibits marked reduction of TBP function in binding to TAF1 as well as temperature sensitivity in in vivo yeast cell growth. Remarkably, the temperature sensitivity was proportional to the length of the linker in the fusions: the construct with (GGGS)(3) linker did not grow at 20 degrees C, while those with (GGGS)(1) and (GGGS)(2) linkers did. These results together indicate that the native interaction between TBP and TAND12 is well maintained in the TAND12-(GGGS)(3)-TBP fusion and that this fusion approach provides an excellent model system to investigate the structural detail of the TBP-TAF1 interaction.
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Affiliation(s)
- Tapas K Mal
- Division of Signaling Biology, Ontario Cancer Institute, Department of Medical Biophysics, University of Toronto, Toronto Medical Discovery Towers, Toronto, Ontario, Canada
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Lotito L, Ferri F, Russo A, Capranico G. DNA topoisomerase i as a transcription protein and a lethal cellular toxin. Ital J Biochem 2007; 56:122-9. [PMID: 17722653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
DNA topoisomerase I constitutes a significant relaxing activity in nuclei of eukaryotic cells. The enzyme acts during several DNA transactions involving the generation of torsional stress in the DNA template. Moreover, antitumor agents targeting DNA topoisomerase I are used in the treatment of human cancers with significant clinical outcome. Major progress has been attained in recent years in the understanding of the basic cellular functions of DNA topoisomerase I. In particular, the consequences of topoisomerase I activity during transcription have been extensively investigated and constitute still a very active research area. Understanding of topoisomerase I inhibitors emphasizes drug activity against the enzyme, however the high drug potency cannot be explained by the DNA damage outcome only. Even though the understanding of enzyme structure has progressed in last years, however more insights into the activity of topoisomerase I poisons have not been achieved yet. Here, we will review landmark investigations on topoisomerase I involvement in different stages of the transcription process, addressing both enzyme functions as well as drug effects on molecular processes. Moreover, we will discuss recent findings on the targeting of topoisomerase I to pre-selected sites in transcribed chromatin by fusion to a sequence-specific DNA-binding protein domain.
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Affiliation(s)
- Luca Lotito
- Department of Biochemistry, University of Bologna, Bologna, Italy
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Pedersen SF, King SA, Nygaard EB, Rigor RR, Cala PM. NHE1 inhibition by amiloride- and benzoylguanidine-type compounds. Inhibitor binding loci deduced from chimeras of NHE1 homologues with endogenous differences in inhibitor sensitivity. J Biol Chem 2007; 282:19716-27. [PMID: 17493937 DOI: 10.1074/jbc.m701637200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The interaction of the ubiquitous Na(+)/H(+) exchanger, NHE1, with its commonly used inhibitors, amiloride- and benzoylguanidine (Hoechst type inhibitor (HOE))-type compounds, is incompletely understood. We previously cloned NHE1 from Amphiuma tridactylum (AtNHE1) and Pleuronectes americanus (PaNHE1). Although highly homologous to the amiloride- and HOE-sensitive human NHE1 (hNHE1), AtNHE1 is insensitive to HOE-type and PaNHE1 to both amiloride- and HOE-type compounds. Here we generated chimeras to "knock in" amiloride and HOE sensitivity to PaNHE1, and we thereby identified several NHE1 regions involved in inhibitor interaction. The markedly different inhibitor sensitivities of hNHE1, AtNHE1, and PaNHE1 could not be accounted for by differences in transmembrane (TM) region 9. Replacing TM10 through the C-terminal tail of PaNHE1 with the corresponding region of AtNHE1 partially restored sensitivity to amiloride and the related compound 5'-(N-ethyl-N-isopropyl)amiloride (EIPA) but not to HOE694. This effect was not due to the tail region, but it was dependent on TM10-11, because replacing only this region with that of AtNHE1 also partially restored amiloride and EIPA but not HOE sensitivity. The converse mutant (TM10-11 of AtNHE1 replaced with those of PaNHE1) exhibited even higher amiloride and EIPA sensitivity and was also HOE-sensitive. Replacing an LFFFY motif in TM region 4 of PaNHE1 with the corresponding residues of hNHE1 (VFFLF) or AtNHE1 (TFFLF) greatly increased sensitivity to both amiloride- and HOE-type compounds, despite the fact that AtNHE1 is HOE694-insensitive. Gain of amiloride sensitivity appeared to correlate with increased Na(+)/H(+) exchange rates. It is concluded that regions within TM4 and TM10-11 contribute to amiloride and HOE sensitivity, with both regions imparting partial inhibitor sensitivity to NHE1.
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Affiliation(s)
- Stine F Pedersen
- Department of Physiology and Membrane Biology, University of California, Davis, California 95616, USA
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35
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Herrick-Davis K, Grinde E, Weaver BA. Serotonin 5-HT(2C) receptor homodimerization is not regulated by agonist or inverse agonist treatment. Eur J Pharmacol 2007; 568:45-53. [PMID: 17507008 PMCID: PMC2205992 DOI: 10.1016/j.ejphar.2007.04.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 03/29/2007] [Accepted: 04/03/2007] [Indexed: 11/30/2022]
Abstract
Serotonin 5-HT(2C) receptors represent targets for therapeutics aimed at treating anxiety, depression, schizophrenia, and obesity. Previously, we demonstrated that 5-HT(2C) receptors function as homodimers. Herein, we investigated the effect of agonist and inverse agonist treatment on the homodimer status of two naturally occurring 5-HT(2C) receptor isoforms, one without basal activity (VGV) and one with constitutive activity (INI) with respect to Galpha(q) signaling. Cyan- and yellow-fluorescent proteins were used to monitor VGV and INI homodimer formation by western blot, and in living cells using bioluminescence and fluorescence resonance energy transfer (BRET and FRET). Western blots of solubilized membrane proteins revealed equal proportions of homodimeric receptor species from HEK293 cells transfected with either the VGV or INI isoform in the absence and presence of 5-HT. BRET ratios measured in HEK293 cells transfected with the VGV or INI isoform were the same and were not modulated by 5-HT. Similarly, FRET efficiencies were the same regardless of whether measured in cells expressing the VGV or INI isoform in the absence or presence of 5-HT or clozapine. The results indicate that serotonin 5-HT(2C) receptors form homodimers regardless of whether they are in an inactive or active conformation and are not regulated by drug treatment.
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Affiliation(s)
- Katharine Herrick-Davis
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, NY 12208, United States.
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36
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Neeper MP, Liu Y, Hutchinson TL, Wang Y, Flores CM, Qin N. Activation properties of heterologously expressed mammalian TRPV2: evidence for species dependence. J Biol Chem 2007; 282:15894-902. [PMID: 17395593 DOI: 10.1074/jbc.m608287200] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TRPV2 has been proposed as a potential pain target, in part due to its relatedness to the nociceptor TRPV1 and to its reported activation by noxious high temperatures (>52 degrees C). However, TRPV2 responses to heat as well as to the nonselective agonist 2-aminoethoxydiphenyl borate (2-APB) have not been universally reproduced in other laboratories, leading to debate about the activation properties of this channel. Here, we report the expression of rat, mouse, and human TRPV2 in HEK293 cells and the differential properties of their responses to heat and 2-APB. Expression of mouse or rat TRPV2 in HEK293 cells resulted in robust channel activation when induced by either temperature (>53 degrees C) or 2-APB. By contrast, expression of human TRPV2 did not lead to detectable activation by either of these stimuli. Human TRPV2 protein was expressed at levels comparable with those of rat TRPV2, exhibited similar surface localization and responded to a novelly identified TRPV2 agonist, Delta(9)-tetrahydrocannabinol, indicating that human TRPV2 is functionally expressed on the cell surface. Studies using deletion mutants and chimeras between rat and human TRPV2 indicated that both amino- and carboxyl-cytoplasmic termini of rat TRPV2 are important for responses to heat and 2-APB but can be supplied in trans to form an active channel. The present study not only confirms and extends previous reports demonstrating that rat and mouse TRPV2 respond to 2-APB and noxious heat but also indicates that further investigation will be required to elucidate TRPV2 activation and regulatory mechanisms.
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Affiliation(s)
- Michael P Neeper
- Analgesics Team, East Coast Research and Early Development, Johnson & Johnson Pharmaceutical Research and Development, L.L.C., Spring House, Pennsylvania 19477-0776, USA
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37
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Grum-Tokars V, Ratia K, Begaye A, Baker SC, Mesecar AD. Evaluating the 3C-like protease activity of SARS-Coronavirus: recommendations for standardized assays for drug discovery. Virus Res 2007; 133:63-73. [PMID: 17397958 PMCID: PMC4036818 DOI: 10.1016/j.virusres.2007.02.015] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 01/24/2007] [Accepted: 02/19/2007] [Indexed: 01/28/2023]
Abstract
Although the initial outbreaks of the deadly coronavirus that causes severe acute respiratory syndrome (SARS-CoV) were controlled by public health measures, the development of vaccines and antiviral agents for SARS-CoV is essential for improving control and treatment of future outbreaks. One potential target for SARS-CoV antiviral drug development is the 3C-like protease (3CLpro). This enzyme is an attractive target since it is essential for viral replication, and since there are now a number of high resolution X-ray structures of SARS-CoV 3CLpro available making structure-based drug-design possible. As a result, SARS-CoV 3CLpro has become the focus of numerous drug discovery efforts worldwide, but as a consequence, a variety of different 3CLpro expression constructs and kinetic assays have been independently developed making evaluation and comparison between potential inhibitors problematic. Here, we review the literature focusing on different SARS-CoV 3CLpro expression constructs and assays used to measure enzymatic activity. Moreover, we provide experimental evidence showing that the activity of 3CLpro enzymatic is significantly reduced when non-native sequences or affinity-tags are added to the N- or C-termini of the enzyme, or when the enzyme used in assays is at concentrations below the equilibrium dissociation constant of the 3CLpro dimer. We demonstrate for the first time the utility of a highly sensitive and novel Alexa488-QSY7 FRET-based peptide substrate designed for routine analysis and high-throughput screening, and show that kinetic constants determined from FRET-based assays that are uncorrected for inner-filter effects can lead to artifacts. Finally, we evaluated the effects of common assay components including DTT, NaCl, EDTA and DMSO on enzymatic activity, and we recommend standardized assay conditions and constructs for routine SARS-CoV 3CLpro assays to facilitate direct comparisons between SARS-CoV 3CLpro inhibitors under development worldwide.
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Affiliation(s)
- Valerie Grum-Tokars
- Center for Pharmaceutical Biotechnology and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, IL 60607, United States
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38
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Leslie EM, Watkins PB, Kim RB, Brouwer KLR. Differential inhibition of rat and human Na+-dependent taurocholate cotransporting polypeptide (NTCP/SLC10A1)by bosentan: a mechanism for species differences in hepatotoxicity. J Pharmacol Exp Ther 2007; 321:1170-8. [PMID: 17374746 DOI: 10.1124/jpet.106.119073] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Bile acid accumulation in hepatocytes due to inhibition of the canalicular bile salt export pump (BSEP/ABCB11) has been proposed as a mechanism for bosentan-induced hepatotoxicity. The observation that bosentan does not induce hepatotoxicity in rats, although bosentan has been reported to inhibit rat Bsep and cause elevated serum bile acids, challenges this mechanism. The lack of hepatotoxicity could be explained if bosentan inhibited hepatocyte uptake as well as canalicular efflux of bile acids. In the current study, bosentan was found to be a more potent inhibitor of Na(+)-dependent taurocholate uptake in rat (IC(50) 5.4 microM) than human (IC(50) 30 microM) suspended hepatocytes. In addition, bosentan was a more potent inhibitor of taurocholate uptake by rat Na(+)-dependent taurocholate co-transporting polypeptide (Ntcp/Slc10a1) (IC(50) 0.71 microM) than human NTCP (SLC10A1) (IC(50) 24 microM) expressed in HEK293 cells. Thus, bosentan is a more potent inhibitor of Ntcp than NTCP, and this should result in less intrahepatocyte accumulation of bile acids in rats during bosentan treatment. To begin characterization of this species difference, two chimeric molecules were generated and expressed in HEK293 cells; NTCP(1-140)/Ntcp(141-362) and Ntcp(1-140)/NTCP(141-349). The mode of bosentan inhibition was noncompetitive for Ntcp, and competitive for NTCP (K(i) 18 microM) and NTCP(1-140)/Ntcp(141-362) (K(i) 1.7 microM); bosentan affected both the K(m) and V(max) of Ntcp(1-140)/NTCP(141-349) (K(i) 7.0 microM). The carboxyl portions of NTCP and Ntcp were found to confer species differences in basal taurocholate transport V(max). In conclusion, differential inhibition of Ntcp and NTCP may represent a novel mechanism for species differences in bosentan-induced hepatotoxicity.
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Affiliation(s)
- Elaine M Leslie
- School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7360, USA
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Maillet EL, Pellegrini N, Valant C, Bucher B, Hibert M, Bourguignon JJ, Galzi JL. A novel, conformation-specific allosteric inhibitor of the tachykinin NK2 receptor (NK2R) with functionally selective properties. FASEB J 2007; 21:2124-34. [PMID: 17371796 DOI: 10.1096/fj.06-7683com] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The orthosteric agonist neurokinin A (NKA) interacts with the tachykinin NK2 receptors (NK2Rs) via an apparent sequential binding process, which stabilizes the receptor in at least two different active conformations (A1L and A2L). The A1L conformation exhibits fast NKA dissociation kinetics and triggers intracellular calcium elevation; the A2L conformation exhibits slow NKA dissociation kinetics and triggers cAMP production. The new compound LPI805 is a partial and noncompetitive inhibitor of NKA binding to NK2Rs. Analysis of NKA dissociation in the presence of LPI805 suggests that LPI805 decreases the number of NKA-NK2R complexes in A2L conformation while increasing those in the A1L conformation. Analysis of signaling pathways of NK2Rs shows that LPI805 dramatically inhibits the NKA-induced cAMP response while slightly enhancing the NKA-induced calcium response. Analysis of NKA association kinetics reveals that LPI805 promotes strong and specific destabilization of the NKA-NK2R complexes in the A2L conformation whereas access of NKA to the A1L conformations is unchanged. Thus, to our knowledge, LPI805 is the first example of a conformation-specific allosteric antagonist of a G-protein-coupled receptor. This work establishes the use of allosteric modulators in order to promote functional selectivity on certain agonist-receptor interactions.
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Affiliation(s)
- Emeline L Maillet
- Departement Recepteurs et Protéines Membranaires; ESBS, Illkirch, France.
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40
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Burkard N, Rokita AG, Kaufmann SG, Hallhuber M, Wu R, Hu K, Hofmann U, Bonz A, Frantz S, Cartwright EJ, Neyses L, Maier LS, Maier SKG, Renné T, Schuh K, Ritter O. Conditional neuronal nitric oxide synthase overexpression impairs myocardial contractility. Circ Res 2007; 100:e32-44. [PMID: 17272813 DOI: 10.1161/01.res.0000259042.04576.6a] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The role of the neuronal NO synthase (nNOS or NOS1) enzyme in the control of cardiac function still remains unclear. Results from nNOS(-/-) mice or from pharmacological inhibition of nNOS are contradictory and do not pay tribute to the fact that probably spatial confinement of the nNOS enzyme is of major importance. We hypothesize that the close proximity of nNOS and certain effector molecules like L-type Ca(2+)-channels has an impact on myocardial contractility. To test this, we generated a new transgenic mouse model allowing conditional, myocardial specific nNOS overexpression. Western blot analysis of transgenic nNOS overexpression showed a 6-fold increase in nNOS protein expression compared with noninduced littermates (n=12; P<0.01). Measuring of total NOS activity by conversion of [(3)H]-l-arginine to [(3)H]-l-citrulline showed a 30% increase in nNOS overexpressing mice (n=18; P<0.05). After a 2 week induction, nNOS overexpression mice showed reduced myocardial contractility. In vivo examinations of the nNOS overexpressing mice revealed a 17+/-3% decrease of +dp/dt(max) compared with noninduced mice (P<0.05). Likewise, ejection fraction was reduced significantly (42% versus 65%; n=15; P<0.05). Interestingly, coimmunoprecipitation experiments indicated interaction of nNOS with SR Ca(2+)ATPase and additionally with L-type Ca(2+)- channels in nNOS overexpressing animals. Accordingly, in adult isolated cardiac myocytes, I(Ca,L) density was significantly decreased in the nNOS overexpressing cells. Intracellular Ca(2+)-transients and fractional shortening in cardiomyocytes were also clearly impaired in nNOS overexpressing mice versus noninduced littermates. In conclusion, conditional myocardial specific overexpression of nNOS in a transgenic animal model reduced myocardial contractility. We suggest that nNOS might suppress the function of L-type Ca(2+)-channels and in turn reduces Ca(2+)-transients which accounts for the negative inotropic effect.
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Affiliation(s)
- Natalie Burkard
- Department of Internal Medicine I, University of Wuerzburg, Wuerzburg, Germany
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Davies TG, Verdonk ML, Graham B, Saalau-Bethell S, Hamlett CCF, McHardy T, Collins I, Garrett MD, Workman P, Woodhead SJ, Jhoti H, Barford D. A structural comparison of inhibitor binding to PKB, PKA and PKA-PKB chimera. J Mol Biol 2007; 367:882-94. [PMID: 17275837 DOI: 10.1016/j.jmb.2007.01.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Revised: 12/20/2006] [Accepted: 01/03/2007] [Indexed: 01/08/2023]
Abstract
Although the crystal structure of the anti-cancer target protein kinase B (PKBbeta/Akt-2) has been useful in guiding inhibitor design, the closely related kinase PKA has generally been used as a structural mimic due to its facile crystallization with a range of ligands. The use of PKB-inhibitor crystallography would bring important benefits, including a more rigorous understanding of factors dictating PKA/PKB selectivity, and the opportunity to validate the utility of PKA-based surrogates. We present a "back-soaking" method for obtaining PKBbeta-ligand crystal structures, and provide a structural comparison of inhibitor binding to PKB, PKA, and PKA-PKB chimera. One inhibitor presented here exhibits no PKB/PKA selectivity, and the compound adopts a similar binding mode in all three systems. By contrast, the PKB-selective inhibitor A-443654 adopts a conformation in PKB and PKA-PKB that differs from that with PKA. We provide a structural explanation for this difference, and highlight the ability of PKA-PKB to mimic the true PKB binding mode in this case.
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Affiliation(s)
- Thomas G Davies
- Astex Therapeutics Ltd, 436 Cambridge Science Park, Milton Road, Cambridge, CB4 0QA, UK.
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De Lorenzo C, Di Malta C, Calì G, Troise F, Nitsch L, D'Alessio G. Intracellular route and mechanism of action of ERB-hRNase, a human anti-ErbB2 anticancer immunoagent. FEBS Lett 2007; 581:296-300. [PMID: 17208233 DOI: 10.1016/j.febslet.2006.12.034] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 12/13/2006] [Accepted: 12/15/2006] [Indexed: 11/21/2022]
Abstract
Human anti-ErbB2 immunoRNase with Erbicin fused to HP-RNase (ERB-hRNase) is a fully human immunoRNase made up of human pancreatic RNase fused to a human anti-ErbB2 scFv. It binds selectively with high affinity to ErbB2-positive cells, and specifically inhibits their proliferation, in vitro and in vivo. An investigation of its mechanism of action and its intracellular destination has revealed that ERB-hRNase depends on its RNase activity for cytotoxic action; it reaches the cytosol directly from the endosomal compartment; it is inhibited by the cytosolic RNase inhibitor (cRI), but the levels that ERB-hRNase reaches in the cytosol neutralize cRI, thus inducing cell death by apoptosis.
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Affiliation(s)
- Claudia De Lorenzo
- Dipartimento di Biologia Strutturale e Funzionale, Università di Napoli Federico II, via Cinthia, 80126 Napoli, Italy
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Abstract
Activity of nuclear receptors is regulated by their nuclear localization. Liver X receptors (LXR) alpha and beta are nuclear receptors that regulate transcription of genes for cholesterol metabolism, cholesterol transport, and lipogenesis. While LXR alpha and beta are very similar in structure and exhibit similar ligand binding properties, their physiological roles are quite different. Since the LXRs fall into a class of receptors that move between the nucleus and cytoplasm, experiments were conducted to determine whether LXR alpha and LXR beta show differences in their nuclear localization pattern. To determine the location of each receptor, cell lines stably expressing yellow fluorescent protein (YFP) chimeras with either LXR alpha or LXR beta were examined. Retention in the nucleus of the chimeric proteins in the presence or absence of ligands was assessed using fluorescence microscopy coupled with digitonin permeabilization assays. Surprisingly, differences were found between LXR alpha and LXR beta. Whereas unliganded LXR alpha was retained in the nucleus, unliganded LXR beta was partially exported. Mutations were then introduced into putative nuclear localization sequences (NLS) to determine which sequences are important for nuclear localization and function. Mutation in one such sequence abolished nuclear localization of LXR alpha, whereas the analogous change in LXR beta had a much less dramatic effect. Mutations in analogous putative NLS also differentially affected transcriptional activation by LXR alpha and LXR beta. These data demonstrate for the first time that nuclear retention and localization as well as function of LXR alpha and LXR beta are differentially regulated.
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Affiliation(s)
- Kirsten Prüfer
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
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Francois JA, Kappock TJ. Alanine racemase from the acidophile Acetobacter aceti. Protein Expr Purif 2007; 51:39-48. [PMID: 16843006 DOI: 10.1016/j.pep.2006.05.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 05/26/2006] [Accepted: 05/27/2006] [Indexed: 11/21/2022]
Abstract
Acetobacter aceti converts ethanol to acetic acid, and survives acetic acid exposure by tolerating cytoplasmic acidification. Alanine racemase (Alr) is a pyridoxal 5' phosphate (PLP) -dependent enzyme that catalyzes the interconversion of the d- and l-isomers of alanine and has a basic pH optimum. Since d-alanine is essential for peptidoglycan biosynthesis, Alr must somehow function in the acidic cytoplasm of A. aceti. We report the partial purification of native A. aceti Alr (AaAlr) and evidence that it is a rather stable enzyme. The C-terminus of AaAlr has a strong resemblance to the ssrA-encoded protein degradation signal, which thwarted initial protein expression experiments. High-activity AaAlr forms lacking a protease recognition sequence were expressed in Escherichia coli and purified. Biophysical and enzymological experiments confirm that AaAlr is intrinsically acid-resistant, yet has the catalytic properties of an ordinary Alr.
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Affiliation(s)
- Julie A Francois
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
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Mikuni S, Pack C, Tamura M, Kinjo M. Diffusion analysis of glucocorticoid receptor and antagonist effect in living cell nucleus. Exp Mol Pathol 2006; 82:163-8. [PMID: 17274977 DOI: 10.1016/j.yexmp.2006.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Accepted: 12/02/2006] [Indexed: 10/23/2022]
Abstract
The diffusion properties of hGRalpha in living cells have been analyzed. The hGRalpha translocalized from the cytosol to the nucleus after addition of Dex just as RU486; however, the Brownian motions of the proteins in nucleus were different. In order to analysis microenvironment of the nucleus of living cell, four different tandem EGFPs were constructed. Diffusion of tandem EGFP was dependent on the length of the protein as a rod-like molecule in solution. We found two kinds of mobility, fast diffusional mobility as a major component and much slower diffusional mobility as a major component in living cells nucleoplasm. On the bases of this analysis, we compared the diffusion property of hGRalpha in the nucleus at the presence of Dex or RU486 by distribution of diffusion constants. Our result may suggest that EGFP-hGRalpha is activated by RU486 and kept the stage of binding cofactor, GRE and final complex. Finally this means that dimerization is not required for association with GRE, although it is required for stabilization of a complex of EGFP-hGRalpha.
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Affiliation(s)
- Shintaro Mikuni
- Laboratory of Supramolecular Biophysics, Research Institute for Electronic Science, Hokkaido University, N12W6, Sapporo 060-0812, Japan
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Zhang YM, Wang Y, Xu QM, Lv BF, Ma DL. [Application of NF-kappaB reporter and Dual-Luciferase assays in the measure of bioactivity of interleukin-1beta and interleukin-1 receptor antagonist]. Beijing Da Xue Xue Bao Yi Xue Ban 2006; 38:653-6. [PMID: 17173090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
OBJECTIVE To develop a reporter gene system based on transient transfections with a NF-kappaB responsive reporter gene to detect the bioactivity of IL-1beta and IL-1 receptor antagonist. METHODS NF-kappaB reporter and Dual-Luciferase assays were applied to measure the bioactivity of IL-1beta and IL-1 receptor antagonist in mouse EL4 cells (some subclones of EL4 cells expressed high level of IL-1 receptor on cell surface). pNF-kappaB-luc and pRL-TK, used as an internal control, were co-transfected into EL4 cells and then the IL-1beta was added. RESULTS The results indicated that IL-1beta was able to induce the expression of this luciferase, which could be blocked by IL-1 receptor antagonist. The optimal dose of IL-1beta was 5 microg/L in Dual-Luciferase assay, whose bioactivity can be effectively inhibited by IL-1ra at 50 microg/L. CONCLUSION We have established a new method to detect the bioactivity of IL-1beta and IL-1 receptor antagonist, which can give repeatable results.
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Affiliation(s)
- Ying-mei Zhang
- Department of Immunology, Peking University School of Basic Medical Science, Peking University, Beijing 100083, China
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Belyi Y, Niggeweg R, Opitz B, Vogelsgesang M, Hippenstiel S, Wilm M, Aktories K. Legionella pneumophila glucosyltransferase inhibits host elongation factor 1A. Proc Natl Acad Sci U S A 2006; 103:16953-8. [PMID: 17068130 PMCID: PMC1636560 DOI: 10.1073/pnas.0601562103] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila, the causal agent of Legionnaires' disease, is an intracellular parasite and invades and proliferates within different eukaryotic cells, including human alveolar macrophages. After several 100-fold multiplication within host cells, the pathogens are released for new invasion by induction of apoptosis or necrosis. Here we report that L. pneumophila produces a glucosyltransferase, which selectively modifies an approximately 50-kDa mammalian protein by using UDP-glucose as a cosubstrate. MS analysis identified the protein substrate as the mammalian elongation factor (EF)1A. Legionella glucosyltransferase modifies its eukaryotic protein substrate at serine-53, which is located in the GTPase domain of the EF. Glucosylation of EF1A results in inhibition of eukaryotic protein synthesis and death of target cells. Our findings show a mode of inhibition of protein synthesis by microbial pathogens and offer a perspective for understanding of the host-pathogen interaction of L. pneumophila.
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Affiliation(s)
- Yury Belyi
- Gamaleya Research Institute, Ulitsa Gamalei 18, Moscow 123098, Russia
| | - Ricarda Niggeweg
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Bastian Opitz
- Department of Internal Medicine/Infectious and Pulmonary Diseases, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; and
| | - Martin Vogelsgesang
- Institute of Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
| | - Stefan Hippenstiel
- Department of Internal Medicine/Infectious and Pulmonary Diseases, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; and
| | - Matthias Wilm
- European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, D-79104 Freiburg, Germany
- To whom correspondence should be addressed. E-mail:
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Breit A, Wolff K, Kalwa H, Jarry H, Büch T, Gudermann T. The natural inverse agonist agouti-related protein induces arrestin-mediated endocytosis of melanocortin-3 and -4 receptors. J Biol Chem 2006; 281:37447-56. [PMID: 17041250 DOI: 10.1074/jbc.m605982200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Agouti-related protein (Agrp), one of the two naturally occurring inverse agonists known to inhibit G protein-coupled receptor activity, regulates energy expenditure by decreasing basal and blocking agonist-promoted melanocortin receptor (MCR) signaling. Here we report that, in addition to its inverse agonistic activities, Agrp exhibits agonistic properties on the endocytosis pathway of melanocortin receptors. Sustained exposure of human embryonic kidney 293 cells to Agrp induced endocytosis of the MC3R or the MC4R. The extent and kinetics of Agrp-promoted MCR endocytosis were similar to the endocytosis induced by melanocortins. Using the bioluminescence resonance energy transfer technique, we further showed that after binding of Agrp both MCRs interacted with beta-arrestins. In line with this observation, in COS-7 cells co-expression of beta-arrestins enhanced Agrp-induced MCR endocytosis, whereas in human embryonic kidney 293 cells co-transfection of beta-arrestin-specific small interference RNAs diminished Agrp-promoted endocytosis. This new regulatory mechanism was likewise detectable in a cell line derived from murine hypothalamic neurons endogenously expressing MC4R, pointing to the physiological relevance of Agrp-promoted receptor endocytosis. In conclusion, we demonstrated that Agrp does not solely act by directly blocking MCR signaling but also by reducing the amount of MCR molecules accessible to melanocortins at the cell surface. This beta-arrestin-dependent mechanism reveals a new aspect of MCR signaling in particular and refines the concept of G protein-coupled receptor antagonism in general.
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MESH Headings
- Agouti-Related Protein
- Animals
- Arrestins/antagonists & inhibitors
- Arrestins/genetics
- Arrestins/metabolism
- Base Sequence
- COS Cells
- Cell Line
- Chlorocebus aethiops
- Cyclic AMP/biosynthesis
- Endocytosis/physiology
- Humans
- Intercellular Signaling Peptides and Proteins/genetics
- Intercellular Signaling Peptides and Proteins/metabolism
- Mice
- Protein Binding
- RNA, Small Interfering/genetics
- Receptor, Melanocortin, Type 3/antagonists & inhibitors
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/antagonists & inhibitors
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Recombinant Fusion Proteins/antagonists & inhibitors
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
- Transfection
- beta-Arrestins
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Affiliation(s)
- Andreas Breit
- Institut für Pharmakologie und Toxikologie, Philipps-Universität Marburg, 35033 Marburg, Germany
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Sahr T, Ravanel S, Basset G, Nichols B, Hanson A, Rébeillé F. Folate synthesis in plants: purification, kinetic properties, and inhibition of aminodeoxychorismate synthase. Biochem J 2006; 396:157-62. [PMID: 16466344 PMCID: PMC1449997 DOI: 10.1042/bj20051851] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
pABA (p-aminobenzoate) is a precursor of folates and, besides esterification to glucose, has no other known metabolic fate in plants. It is synthesized in two steps from chorismate and glutamine, the first step being their conversion into glutamate and ADC (4-aminodeoxychorismate). In Escherichia coli, two proteins forming a heterodimeric complex are required for this reaction, but, in plants and lower eukaryotes, a single protein is involved. The Arabidopsis enzyme was expressed in E. coli and was purified to homogeneity. The monomeric enzyme (95 kDa) catalyses two reactions: release of NH3 from glutamine (glutaminase activity) and substitution of NH3 for the hydroxy group at position 4 of chorismate (ADC synthase activity). The kinetic parameters of the plant enzyme are broadly similar to those of the bacterial complex, with K(m) values for glutamine and chorismate of 600 and 1.5 microM respectively. As with the bacterial enzyme, externally added NH3 was a very poor substrate for the plant enzyme, suggesting that NH3 released from glutamine is preferentially channelled to chorismate. The glutaminase activity could operate alone, but the presence of chorismate increased the efficiency of the reaction 10-fold, showing the interdependency of the two domains. The plant enzyme was inhibited by dihydrofolate and its analogue methotrexate, a feature never reported for the prokaryotic system. These molecules were inhibitors of the glutaminase reaction, competitive with respect to glutamine (K(i) values of 10 and 1 microM for dihydrofolate and methotrexate respectively). These findings support the view that the monomeric ADC synthase is a potential target for antifolate drugs.
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Affiliation(s)
- Tobias Sahr
- *Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - Stéphane Ravanel
- *Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
| | - Gilles Basset
- †Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Brian P. Nichols
- ‡Department of Biological Sciences, University of Illinois, Chicago, IL 60607, U.S.A
| | - Andrew D. Hanson
- †Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Fabrice Rébeillé
- *Laboratoire de Physiologie Cellulaire Végétale, UMR5168 CNRS-CEA-INRA-Université Joseph Fourier Grenoble I, Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France
- To whom correspondence should be addressed (email )
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Couderc B, Penary M, Tohfe M, Pradines A, Casteignau A, Berg D, Favre G. Reversible inactivation of the transcriptional function of P53 protein by farnesylation. BMC Biotechnol 2006; 6:26. [PMID: 16732889 PMCID: PMC1481662 DOI: 10.1186/1472-6750-6-26] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 05/29/2006] [Indexed: 11/29/2022] Open
Abstract
Background The use of integrating viral vectors in Gene therapy clinical trials has pointed out the problem of the deleterous effect of the integration of the ectopic gene to the cellular genome and the safety of this strategy. We proposed here a way to induce the death of gene modified cells upon request by acting on a pro-apoptotic protein cellular localization and on the activation of its apoptotic function. Results We constructed an adenoviral vector coding a chimeric p53 protein by fusing p53 sequence with the 21 COOH term amino acids sequence of H-Ras. Indeed, the translation products of Ras genes are cytosolic proteins that become secondarily associated with membranes through a series of post-translational modifications initiated by a CAAX motif present at the C terminus of Ras proteins. The chimeric p53HRCaax protein was farnesylated efficiently in transduced human osteosarcoma p53-/- cell line. The farnesylated form of p53 resided mainly in the cytosol, where it is non-functional. Farnesyl transferase inhibitors (FTIs) specifically inhibited farnesyl isoprenoid lipid modification of proteins. Following treatment of the cells with an FTI, p53HRCaax underwent translocation into the nucleus where it retained transcription factor activity. Shifting p53 into the nucleus resulted in the induction of p21waf1/CIP1 and Bax transcription, cell growth arrest, caspase activation and apoptosis. Conclusion Artificial protein farnesylation impaired the transcriptional activity of p53. This could be prevented by Farnesyl transferase inhibition. These data highlight the fact that the artificial prenylation of proteins provides a novel system for controlling the function of a transactivating factor.
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Affiliation(s)
- Bettina Couderc
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Marie Penary
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Mustapha Tohfe
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Anne Pradines
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Antoine Casteignau
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Danièle Berg
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
| | - Gilles Favre
- INSERM U563, Department Innovations thérapeutiques et Oncologie moléculaire, Institut Claudius Regaud and Faculté des Sciences Pharmaceutiques, Toulouse, France
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