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Gopalakrishnapillai A, Correnti CE, Pilat K, Lin I, Chan MK, Bandaranayake AD, Mehlin C, Kisielewski A, Hamill D, Kaeding AJ, Meshinchi S, Olson JM, Kolb EA, Barwe SP. Immunotherapeutic Targeting of Mesothelin Positive Pediatric AML Using Bispecific T Cell Engaging Antibodies. Cancers (Basel) 2021; 13:cancers13235964. [PMID: 34885074 PMCID: PMC8657033 DOI: 10.3390/cancers13235964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 12/20/2022] Open
Abstract
Simple Summary Immunotherapy development in pediatric AML has been slow due to the paucity of validated AML-specific targets. We recently identified mesothelin (MSLN) as a therapeutic target in pediatric AML. Mice receiving T cell engaging bispecific antibodies (BsAbs) targeting MSLN and CD3 achieved complete remission and durable responses in two MSLN-positive patient-derived xenograft (PDX) models. This is a first report showing MSLN-targeting BsAbs are a viable immunotherapy for MSLN-positive pediatric AML. Abstract Advances in the treatment of pediatric AML have been modest over the past four decades. Despite maximally intensive therapy, approximately 40% of patients will relapse. Novel targeted therapies are needed to improve outcomes. We identified mesothelin (MSLN), a well-validated target overexpressed in some adult malignancies, to be highly expressed on the leukemic cell surface in a subset of pediatric AML patients. The lack of expression on normal bone marrow cells makes MSLN a viable target for immunotherapies such as T-cell engaging bispecific antibodies (BsAbs) that combine two distinct antibody-variable regions into a single molecule targeting a cancer-specific antigen and the T-cell co-receptor CD3. Using antibody single-chain variable region (scFv) sequences derived from amatuximab-recognizing MSLN, and from either blinatumomab or AMG330 targeting CD3, we engineered and expressed two MSLN/CD3-targeting BsAbs: MSLNAMA-CD3L2K and MSLNAMA-CD3AMG, respectively. Both BsAbs promoted T-cell activation and reduced leukemic burden in MV4;11:MSLN xenografted mice, but not in those transplanted with MSLN-negative parental MV4;11 cells. MSLNAMA-CD3AMG induced complete remission in NTPL-146 and DF-5 patient-derived xenograft models. These data validate the in vivo efficacy and specificity of MSLN-targeting BsAbs. Because prior MSLN-directed therapies appeared safe in humans, MSLN-targeting BsAbs could be ideal immunotherapies for MSLN-positive pediatric AML patients.
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Affiliation(s)
- Anilkumar Gopalakrishnapillai
- Nemours Centers for Childhood Cancer Research & Cancer and Blood Disorders, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; (A.G.); (A.K.); (D.H.); (E.A.K.)
| | - Colin E. Correnti
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Kristina Pilat
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Ida Lin
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Man Kid Chan
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Ashok D. Bandaranayake
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Christopher Mehlin
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Anne Kisielewski
- Nemours Centers for Childhood Cancer Research & Cancer and Blood Disorders, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; (A.G.); (A.K.); (D.H.); (E.A.K.)
| | - Darcy Hamill
- Nemours Centers for Childhood Cancer Research & Cancer and Blood Disorders, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; (A.G.); (A.K.); (D.H.); (E.A.K.)
| | - Allison J. Kaeding
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Soheil Meshinchi
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - James M. Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; (C.E.C.); (K.P.); (I.L.); (M.K.C.); (A.D.B.); (C.M.); (A.J.K.); (S.M.); (J.M.O.)
| | - Edward Anders Kolb
- Nemours Centers for Childhood Cancer Research & Cancer and Blood Disorders, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; (A.G.); (A.K.); (D.H.); (E.A.K.)
| | - Sonali P. Barwe
- Nemours Centers for Childhood Cancer Research & Cancer and Blood Disorders, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, USA; (A.G.); (A.K.); (D.H.); (E.A.K.)
- Correspondence: ; Tel.: +1-302-651-6542
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Cook Sangar ML, Girard EJ, Hopping G, Yin C, Pakiam F, Brusniak MY, Nguyen E, Ruff R, Gewe MM, Byrnes-Blake K, Nairn NW, Miller DM, Mehlin C, Strand AD, Mhyre AJ, Correnti CE, Strong RK, Simon JA, Olson JM. A potent peptide-steroid conjugate accumulates in cartilage and reverses arthritis without evidence of systemic corticosteroid exposure. Sci Transl Med 2021; 12:12/533/eaay1041. [PMID: 32132215 DOI: 10.1126/scitranslmed.aay1041] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/23/2020] [Indexed: 12/12/2022]
Abstract
On-target, off-tissue toxicity limits the systemic use of drugs that would otherwise reduce symptoms or reverse the damage of arthritic diseases, leaving millions of patients in pain and with limited physical mobility. We identified cystine-dense peptides (CDPs) that rapidly accumulate in cartilage of the knees, ankles, hips, shoulders, and intervertebral discs after systemic administration. These CDPs could be used to concentrate arthritis drugs in joints. A cartilage-accumulating peptide, CDP-11R, reached peak concentration in cartilage within 30 min after administration and remained detectable for more than 4 days. Structural analysis of the peptides by crystallography revealed that the distribution of positive charge may be a distinguishing feature of joint-accumulating CDPs. In addition, quantitative whole-body autoradiography showed that the disulfide-bonded tertiary structure is critical for cartilage accumulation and retention. CDP-11R distributed to joints while carrying a fluorophore imaging agent or one of two different steroid payloads, dexamethasone (dex) and triamcinolone acetonide (TAA). Of the two payloads, the dex conjugate did not advance because the free drug released into circulation was sufficient to cause on-target toxicity. In contrast, the CDP-11R-TAA conjugate alleviated joint inflammation in the rat collagen-induced model of rheumatoid arthritis while avoiding toxicities that occurred with nontargeted steroid treatment at the same molar dose. This conjugate shows promise for clinical development and establishes proof of concept for multijoint targeting of disease-modifying therapeutic payloads.
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Affiliation(s)
- Michelle L Cook Sangar
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Emily J Girard
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Gene Hopping
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Chunfeng Yin
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Fiona Pakiam
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Mi-Youn Brusniak
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Elizabeth Nguyen
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Raymond Ruff
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Mesfin M Gewe
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | | | | | | | - Christopher Mehlin
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Andrew D Strand
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Andrew J Mhyre
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Colin E Correnti
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Roland K Strong
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Julian A Simon
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.,Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
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3
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Correnti CE, Gewe MM, Mehlin C, Bandaranayake AD, Johnsen WA, Rupert PB, Brusniak MY, Clarke M, Burke SE, De Van Der Schueren W, Pilat K, Turnbaugh SM, May D, Watson A, Chan MK, Bahl CD, Olson JM, Strong RK. Screening, large-scale production and structure-based classification of cystine-dense peptides. Nat Struct Mol Biol 2018; 25:270-278. [PMID: 29483648 PMCID: PMC5840021 DOI: 10.1038/s41594-018-0033-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [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: 09/26/2017] [Accepted: 01/23/2018] [Indexed: 12/04/2022]
Abstract
Peptides folded through interwoven disulfides display extreme biochemical properties and unique medicinal potential. However, their exploitation has been hampered by the limited amounts isolatable from natural sources and the expense of chemical synthesis. We developed reliable biological methods for high-throughput expression, screening and large-scale production of these peptides: 46 were successfully produced in multimilligram quantities, and >600 more were deemed expressible through stringent screening criteria. Many showed extreme resistance to temperature, proteolysis and/or reduction, and all displayed inhibitory activity against at least 1 of 20 ion channels tested, thus confirming their biological functionality. Crystal structures of 12 confirmed proper cystine topology and the utility of crystallography to study these molecules but also highlighted the need for rational classification. Previous categorization attempts have focused on limited subsets featuring distinct motifs. Here we present a global definition, classification and analysis of >700 structures of cystine-dense peptides, providing a unifying framework for these molecules.
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Affiliation(s)
- Colin E Correnti
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Mesfin M Gewe
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Christopher Mehlin
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Ashok D Bandaranayake
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - William A Johnsen
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Peter B Rupert
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Mi-Youn Brusniak
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Midori Clarke
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Skyler E Burke
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - Kristina Pilat
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Shanon M Turnbaugh
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Damon May
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Alex Watson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Man Kid Chan
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | | | - James M Olson
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
| | - Roland K Strong
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
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Olson JM, Strong R, Mehlin C, Correnti C. Abstract 2443: Optides (optimized peptides), a new knottin-based cancer drug discovery platform. Cancer Res 2015. [DOI: 10.1158/1538-7445.am2015-2443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Some of the highest value targets in cancer therapeutics involve protein:protein interactions that are difficult to inhibit with small molecule therapeutics. Peptide drug candidates offer an alternative, but many peptide drugs have poor pharmacokinetic properties and some are immunogenic. Knottin peptides have long been promoted as scaffolds for human drug discovery efforts because the exquisitely tight knot formed by disulfide bridges creates resistance to proteolytic and other forms of degradation. Furthermore, some knottins cross the blood brain barrier, the gut wall, or cell membranes which is ideal for certain targets. Unfortunately, creating knottins synthetically or in bacteria results in a large number of disulfide isomers, which has hampered research. We have created a mammalian expression system that enables production of most knottin scaffolds and variants of native knottins encoded in plant and animal genomes. The platform routinely produces approximately 10 mg/liter of near pure naked peptide, which is sufficient to conduct in vivo studies without major scale-up. The system is endotoxin free. In addition to building the platform, we identified over 200,000 new potential knottin peptides in various genomes, creating a rich collection of scaffolds from which to establish diversity libraries of native and optimized variants. These candidates have potential for targeting therapeutics to cancer cells as a solid tumor penetrating alternative to antibody drug conjugates. Optides also have potential to be developed as anti-cancer drugs themselves. The fact that knottin peptides are not substrates for resistance mechanisms such as p-glycoprotein pumps underscores the potential importance of this class of drugs for those with previously treated cancer.
Citation Format: James M. Olson, Roland Strong, Christopher Mehlin, Colin Correnti. Optides (optimized peptides), a new knottin-based cancer drug discovery platform. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2443. doi:10.1158/1538-7445.AM2015-2443
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Shen M, Siu S, Byrd S, Edelmann KH, Patel N, Ketchem RR, Mehlin C, Arnett HA, Hasegawa H. Diverse functions of reactive cysteines facilitate unique biosynthetic processes of aggregate-prone interleukin-31. Exp Cell Res 2011; 317:976-93. [DOI: 10.1016/j.yexcr.2010.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 10/18/2022]
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Zhang J, Carter J, Siu S, O'Neill JW, Gates AH, Delaney J, Mehlin C. Fusion partners as a tool for the expression of difficult proteins in mammalian cells. Curr Pharm Biotechnol 2010; 11:241-5. [PMID: 20210749 DOI: 10.2174/138920110791111898] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 01/26/2010] [Indexed: 11/22/2022]
Abstract
The expression of proteins which do not express well on their own can be enhanced by linking them to human serum albumin (HSA) or antibody crystallizable fragment (Fc). The constructs shown here are designed to secrete the proteins after transient transfection of mammalian cell lines. The fusion partners are appended to the N-terminus of the proteins and contain a linker designed to be proteolytically cleaved. Transient transfection and purification protocols are provided as well as experimental results with five interleukins.
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Affiliation(s)
- Jue Zhang
- Amgen, Inc. Department of Protein Science, Seattle, Seattle, WA 98119, USA
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Lim AC, Ketchem RR, Borges L, Carabeo T, Carter J, Hoover JE, Hu Z, Wittekind M, Zhou H, Mehlin C. A diversity of antibody epitopes can induce signaling through the erythropoietin receptor. Biochemistry 2010; 49:3797-804. [PMID: 20337434 DOI: 10.1021/bi1001147] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stimulation of red cell production through agonism of the erythropoietin receptor (EpoR) has historically been accomplished through administration of erythropoietin (EPO), the native ligand. The short half-life of EPO has led to the development of a variety of other agonists, including antibodies. It is of considerable interest to understand how these agents might activate the EpoR and whether or not it is important to bind in a manner similar to the native ligand. The binding epitopes of a panel of eight agonistic, single-chain antibody (scFv-Fc) constructs were determined through scanning alanine mutagenesis as well as more limited arginine mutagenesis of the receptor. It was found that while some of these constructs bound to receptor epitopes shared by the ligand, others bound in completely unique ways. The use of a panel of agonists and scanning mutagenesis can define the critical binding regions for signaling; in the case of the EpoR, these regions were remarkably broad.
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Affiliation(s)
- Ai Ching Lim
- Amgen, Inc., 1201 Amgen Court West AW2/3152, Seattle, Washington 98119-3105, USA
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Carter J, Zhang J, Dang TL, Hasegawa H, Cheng JD, Gianan I, O'Neill JW, Wolfson M, Siu S, Qu S, Meininger D, Kim H, Delaney J, Mehlin C. Fusion partners can increase the expression of recombinant interleukins via transient transfection in 2936E cells. Protein Sci 2010; 19:357-62. [PMID: 20014434 DOI: 10.1002/pro.307] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The expression levels of five secreted target interleukins (IL-11, 15, 17B, 32, and IL23 p19 subunit) were tested with three different fusion partners in 2936E cells. When fused to the N-terminus, human serum albumin (HSA) was found to enhance the expression of both IL-17B and IL-15, cytokines which did not express at measurable levels on their own. Although the crystallizable fragment of an antibody (Fc) was also an effective fusion partner for IL-17B, Fc did not increase expression of IL-15. Fc was superior to HSA for the expression of the p19 subunit of IL-23, but no partner led to measurable levels of IL-32gamma secretion. Glutathione S-transferase (GST) did not enhance the expression of any target and suppressed the production of IL-11, a cytokine which expressed robustly both on its own and when fused to HSA or Fc. Cleavage of the fusion partner was not always possible. The use of HSA or Fc as N-terminal fusions can be an effective technique to express difficult proteins, especially for applications in which the fusion partner need not be removed.
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Affiliation(s)
- Jane Carter
- Department of Protein Science, Amgen, Inc., Seattle, Washington 98119, USA
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Bosch J, Robien MA, Mehlin C, Boni E, Riechers A, Buckner FS, Van Voorhis WC, Myler PJ, Worthey EA, DeTitta G, Luft JR, Lauricella A, Gulde S, Anderson LA, Kalyuzhniy O, Neely HM, Ross J, Earnest TN, Soltis M, Schoenfeld L, Zucker F, Merritt EA, Fan E, Verlinde CLMJ, Hol WGJ. Using fragment cocktail crystallography to assist inhibitor design of Trypanosoma brucei nucleoside 2-deoxyribosyltransferase. J Med Chem 2006; 49:5939-46. [PMID: 17004709 DOI: 10.1021/jm060429m] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [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: 11/28/2022]
Abstract
The 1.8 A resolution de novo structure of nucleoside 2-deoxyribosyltransferase (EC 2.4.2.6) from Trypanosoma brucei (TbNDRT) has been determined by SADa phasing in an unliganded state and several ligand-bound states. This enzyme is important in the salvage pathway of nucleoside recycling. To identify novel lead compounds, we exploited "fragment cocktail soaks". Out of 304 compounds tried in 31 cocktails, four compounds could be identified crystallographically in the active site. In addition, we demonstrated that very short soaks of approximately 10 s are sufficient even for rather hydrophobic ligands to bind in the active site groove, which is promising for the application of similar soaking experiments to less robust crystals of other proteins.
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Affiliation(s)
- Jürgen Bosch
- Department of Biochemistry, Division of Infectious Disease, and Howard Hughes Medical Institute, University of Washington, Seattle, Washington 98195, USA
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Robien MA, Bosch J, Buckner FS, Van Voorhis WCE, Worthey EA, Myler P, Mehlin C, Boni EE, Kalyuzhniy O, Anderson L, Lauricella A, Gulde S, Luft JR, DeTitta G, Caruthers JM, Hodgson KO, Soltis M, Zucker F, Verlinde CLMJ, Merritt EA, Schoenfeld LW, Hol WGJ. Crystal structure of glyceraldehyde-3-phosphate dehydrogenase from Plasmodium falciparum at 2.25 A resolution reveals intriguing extra electron density in the active site. Proteins 2006; 62:570-7. [PMID: 16345073 DOI: 10.1002/prot.20801] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [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: 11/10/2022]
Abstract
The crystal structure of D-glyceraldehyde-3-phosphate dehydrogenase (PfGAPDH) from the major malaria parasite Plasmodium falciparum is solved at 2.25 A resolution. The structure of PfGAPDH is of interest due to the dependence of the malaria parasite in infected human erythrocytes on the glycolytic pathway for its energy generation. Recent evidence suggests that PfGAPDH may also be required for other critical activities such as apical complex formation. The cofactor NAD(+) is bound to all four subunits of the tetrameric enzyme displaying excellent electron densities. In addition, in all four subunits a completely unexpected large island of extra electron density in the active site is observed, approaching closely the nicotinamide ribose of the NAD(+). This density is most likely the protease inhibitor AEBSF, found in maps from two different crystals. This putative AEBSF molecule is positioned in a crucial location and hence our structure, with expected and unexpected ligands bound, can be of assistance in lead development and design of novel antimalarials.
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Affiliation(s)
- Mark A Robien
- Structural Genomics of Pathogenic Protozoa (SGPP), Department of Biochemistry, University of Washington, Seattle 98195, USA
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Holmes MA, Buckner FS, Van Voorhis WC, Verlinde CLMJ, Mehlin C, Boni E, DeTitta G, Luft J, Lauricella A, Anderson L, Kalyuzhniy O, Zucker F, Schoenfeld LW, Earnest TN, Hol WGJ, Merritt EA. Structure of ribose 5-phosphate isomerase from Plasmodium falciparum. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:427-31. [PMID: 16682767 PMCID: PMC2219984 DOI: 10.1107/s1744309106010876] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [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] [Received: 02/18/2006] [Accepted: 03/24/2006] [Indexed: 11/10/2022]
Abstract
The structure of ribose 5-phosphate isomerase from Plasmodium falciparum, PFE0730c, has been determined by molecular replacement at 2.09 angstroms resolution. The enzyme, which catalyzes the isomerization reaction that interconverts ribose 5-phosphate and ribulose 5-phosphate, is a member of the pentose phosphate pathway. The P. falciparum enzyme belongs to the ribose 5-phosphate isomerase A family, Pfam family PF06562 (DUF1124), and is structurally similar to other members of the family.
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Affiliation(s)
- Margaret A. Holmes
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Frederick S. Buckner
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Wesley C. Van Voorhis
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Christophe L. M. J. Verlinde
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Christopher Mehlin
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Erica Boni
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - George DeTitta
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Joseph Luft
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Angela Lauricella
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Lori Anderson
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Oleksandr Kalyuzhniy
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Frank Zucker
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Lori W. Schoenfeld
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Thomas N. Earnest
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Wim G. J. Hol
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Ethan A. Merritt
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
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12
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Mehlin C, Boni E, Buckner FS, Engel L, Feist T, Gelb MH, Haji L, Kim D, Liu C, Mueller N, Myler PJ, Reddy JT, Sampson JN, Subramanian E, Van Voorhis WC, Worthey E, Zucker F, Hol WGJ. Heterologous expression of proteins from Plasmodium falciparum: results from 1000 genes. Mol Biochem Parasitol 2006; 148:144-60. [PMID: 16644028 DOI: 10.1016/j.molbiopara.2006.03.011] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [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: 12/28/2005] [Revised: 03/16/2006] [Accepted: 03/21/2006] [Indexed: 11/19/2022]
Abstract
As part of a structural genomics initiative, 1000 open reading frames from Plasmodium falciparum, the causative agent of the most deadly form of malaria, were tested in an E. coli protein expression system. Three hundred and thirty-seven of these targets were observed to express, although typically the protein was insoluble. Sixty-three of the targets provided soluble protein in yields ranging from 0.9 to 406.6 mg from one liter of rich media. Higher molecular weight, greater protein disorder (segmental analysis, SEG), more basic isoelectric point (pI), and a lack of homology to E. coli proteins were all highly and independently correlated with difficulties in expression. Surprisingly, codon usage and the percentage of adenosines and thymidines (%AT) did not appear to play a significant role. Of those proteins which expressed, high pI and a hypothetical annotation were both strongly and independently correlated with insolubility. The overwhelmingly important role of pI in both expression and solubility appears to be a surprising and fundamental issue in the heterologous expression of P. falciparum proteins in E. coli. Twelve targets which did not express in E. coli from the native gene sequence were codon-optimized through whole gene synthesis, resulting in the (insoluble) expression of three of these proteins. Seventeen targets which were expressed insolubly in E. coli were moved into a baculovirus/Sf-21 system, resulting in the soluble expression of one protein at a high level and six others at a low level. A variety of factors conspire to make the heterologous expression of P. falciparum proteins challenging, and these observations lay the groundwork for a rational approach to prioritizing and, ultimately, eliminating these impediments.
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Affiliation(s)
- Christopher Mehlin
- Structural Genomics of Pathogenic Protozoa, Box 357350, University of Washington, Seattle, WA 98195, USA.
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13
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Holmes MA, Buckner FS, Van Voorhis WC, Mehlin C, Boni E, Earnest TN, DeTitta G, Luft J, Lauricella A, Anderson L, Kalyuzhniy O, Zucker F, Schoenfeld LW, Hol WGJ, Merritt EA. Structure of the conserved hypothetical protein MAL13P1.257 from Plasmodium falciparum. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:180-5. [PMID: 16511296 PMCID: PMC2197184 DOI: 10.1107/s1744309106005847] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [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] [Received: 12/27/2005] [Accepted: 02/16/2006] [Indexed: 05/06/2023]
Abstract
The structure of a conserved hypothetical protein, PlasmoDB sequence MAL13P1.257 from Plasmodium falciparum, Pfam sequence family PF05907, has been determined as part of the structural genomics effort of the Structural Genomics of Pathogenic Protozoa consortium. The structure was determined by multiple-wavelength anomalous dispersion at 2.17 A resolution. The structure is almost entirely beta-sheet; it consists of 15 beta-strands and one short 3(10)-helix and represents a new protein fold. The packing of the two monomers in the asymmetric unit indicates that the biological unit may be a dimer.
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Affiliation(s)
- Margaret A. Holmes
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Frederick S. Buckner
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Wesley C. Van Voorhis
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Christopher Mehlin
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Erica Boni
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Thomas N. Earnest
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - George DeTitta
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Joseph Luft
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Angela Lauricella
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Hauptman–Woodward Institute, Buffalo, NY 14203, USA
| | - Lori Anderson
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Oleksandr Kalyuzhniy
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Frank Zucker
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Lori W. Schoenfeld
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
| | - Wim G. J. Hol
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
| | - Ethan A. Merritt
- Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, USA
- Department of Biochemistry, University of Washington, Seattle, WA 98195-7742, USA
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14
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Caruthers J, Bosch J, Buckner F, Van Voorhis W, Myler P, Worthey E, Mehlin C, Boni E, DeTitta G, Luft J, Lauricella A, Kalyuzhniy O, Anderson L, Zucker F, Soltis M, Hol WGJ. Structure of a ribulose 5-phosphate 3-epimerase from Plasmodium falciparum. Proteins 2005; 62:338-42. [PMID: 16304640 DOI: 10.1002/prot.20764] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [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: 11/11/2022]
Abstract
The crystal structure of Pfal009167AAA, a putative ribulose 5-phosphate 3-epimerase (PfalRPE) from Plasmodium falciparum, has been determined to 2 A resolution. RPE represents an exciting potential drug target for developing antimalarials because it is involved in the shikimate and the pentose phosphate pathways. The structure is a classic TIM-barrel fold. A coordinated Zn ion and a bound sulfate ion in the active site of the enzyme allow for a greater understanding of the mechanism of action of this enzyme. This structure is solved in the framework of the Structural Genomics of Pathogenic Protozoa (SGPP) consortium.
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Affiliation(s)
- J Caruthers
- SLAC, Stanford University, Menlo Park, California, USA
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15
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Abstract
X-ray crystallography is a technique which is finding increasing utility in the effort to find new antimalarial drugs. This is in spite of the serious difficulties often encountered in obtaining sufficient quantities of protein to crystallize. This review provides an overview of the Plasmodium falciparum proteins which have been crystallized with bound inhibitors and the methodology employed in the heterologous expression of these proteins. Lactate dehydrogenase, plasmepsin II, and triosphosphate isomerase are the most advanced targets of structure-based drug design, but nine other P. falciparum proteins have been crystallized with inhibitors as well, and this is clearly an area which is moving very quickly. Some consideration will also be given to the limitations of structure-based drug discovery with respect to known antimalarial drugs.
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Affiliation(s)
- Christopher Mehlin
- University of Washington, Structural Genomics of Pathogenic Protozoa, Box 357350 Department of Biochemistry, Seattle, WA 98195, USA.
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16
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Abstract
The discovery of a sulphonamide by-product with VLA-4 antagonistic activity led to a series of potent, small molecule VLA-4 antagonists. Synthesis, SAR and in vivo evaluation of the selected compound will be presented.
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Affiliation(s)
- Marcin Stasiak
- Molecumetics, 2023 120th Avenue N E., Bellevue, WA 98005, USA
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17
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Mehlin C. Measurement of VLA-4/CS-1 and VLA-4/VCAM adhesion inhibition. Curr Protoc Pharmacol 2004; Chapter 12:Unit 12.7. [PMID: 22294119 DOI: 10.1002/0471141755.ph1207s24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cell adhesion, a critical early step in the inflammatory process, has increasingly become the target of drug discovery efforts. Described in this unit are techniques for measuring inhibitors of VLA-4-mediated adhesion to either VCAM or the connecting segment (CS-1) of fibronectin.
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18
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Abstract
Cloning grills are aluminum grids designed to divide an agar plate into segments, thereby multiplying the number of E. coli cultures which can be streaked out on a single plate. The grills are autoclaved and placed in square petri dishes immediately after hot agar is poured. When the agar solidifies, the grill remains embedded in the media, and each of the 12 lanes accommodates the streaking out of a single culture. As the spacing of the grill lanes is the same as that of a 96-well plate, 12 cultures can be streaked at a time using a 12-channel pipette. This allows a plate of 96 cultures to be rapidly and accurately plated for colony isolation on only eight agar plates.
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Affiliation(s)
- Christopher Mehlin
- Structural Genomics of Pathogenic Protozoa (SGPP), Department of Biochemistry, University of Washington, Box 357350, Seattle, WA 98195, USA.
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19
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Deng J, Davies DR, Wisedchaisri G, Wu M, Hol WGJ, Mehlin C. An improved protocol for rapid freezing of protein samples for long-term storage. Acta Crystallogr D Biol Crystallogr 2003; 60:203-4. [PMID: 14684931 DOI: 10.1107/s0907444903024491] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2003] [Accepted: 10/23/2003] [Indexed: 11/10/2022]
Abstract
Freezing of purified protein drops directly in liquid nitrogen is a convenient technique for the long-term storage of protein samples. Although this enhances reproducibility in follow-up crystallization experiments, some protein samples are not amenable to this technique. It has been discovered that plunging PCR tubes containing protein samples into liquid nitrogen results in more rapid freezing of the samples and can safely preserve some proteins that are damaged by drop-freezing. The PCR-tube method can also be adapted to a PCR-plate freezing method with applications for high-throughput and structural genomics projects.
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Affiliation(s)
- Junpeng Deng
- Department of Biochemistry, University of Washington, USA, and Howard Hughes Medical Institute, USA
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21
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Abstract
Staphylococcus epidermidis releases factors that activate the HIV-1 long terminal repeat, induce cytokine release, and activate nuclear factor B in cells of macrophage lineage. The active material had a mass of 34,500 daltons, was inactivated by proteases and partitioned into the phenol layer on hot aqueous phenol extraction, and thus was termed phenol-soluble modulin (PSM). High performance liquid chromatography (HPLC) of crude PSM yielded two peaks of activity designated PSM peak 1 and peak 2. MALDI-TOF (matrix-assisted laser desorption ionization-time of flight) mass spectroscopy indicated the presence of two components in peak 1, which were designated PSM and PSM. Peak 2 contained a single component, designated PSM. Separation of PSM and PSM in peak 1 could be achieved by a second HPLC procedure. The structure of each component was determined by amino acid sequence analysis and identification and sequencing of their genes. PSM, PSM, and PSM were 22-, 44-, and 25-amino acid, respectively, strongly hydrophobic polypeptides. PSM was identified as Staphylococcus epidermidis delta toxin, whereas PSM and PSM exhibited more distant homology to previously described staphylococcal toxins. They appeared to exist as a complex or aggregate with activity greater than the component parts. The properties of the S. epidermidis PSMs suggest that they may contribute to the systemic manifestations of Gram-positive sepsis.
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Affiliation(s)
- C Mehlin
- Department of Pathobiology, University of Washington, Seattle, Washington 98195, USA
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22
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Klebanoff SJ, Watts DH, Mehlin C, Headley CM. Lactobacilli and vaginal host defense: activation of the human immunodeficiency virus type 1 long terminal repeat, cytokine production, and NF-kappaB. J Infect Dis 1999; 179:653-60. [PMID: 9952372 DOI: 10.1086/314644] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [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] [Indexed: 11/03/2022] Open
Abstract
Lactobacilli, a component of the normal vaginal flora, can activate the human immunodeficiency virus (HIV)-1 long terminal repeat (LTR) in the Jurkat T lymphocyte and THP-1 macrophage cell lines. Activation of the LTR in Jurkat cells was strongly enhanced by vanadate and inhibited by catalase, implicating H2O2. In contrast, activation in THP-1 cells occurred in the absence of vanadate and was unaffected by catalase. The active material partitioned into the phenol layer on hot aqueous phenol extraction. Lactobacilli also increased tumor necrosis factor-alphaand interleukin-1betaproduction and activated NF-kappaB in THP-1 cells and increased tumor necrosis factor-alphaproduction by human monocytes. Human vaginal fluid specimens had comparable properties, which correlated with their bacterial content. These findings suggest the presence in vaginal fluid of agent(s) derived from indigenous bacteria that can activate the HIV-1 LTR, cytokine production, and NF-kappaB in cells of macrophage lineage, with possible influence on vaginal physiology and host defense.
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Affiliation(s)
- S J Klebanoff
- Department of Medicine, University of Washington, Seattle, WA 98195-7185, USA.
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23
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Klebanoff SJ, Mehlin C, Headley CM. Activation of the HIV type 1 long terminal repeat and viral replication by dimethylsulfoxide and related solvents. AIDS Res Hum Retroviruses 1997; 13:1221-7. [PMID: 9310289 DOI: 10.1089/aid.1997.13.1221] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [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: 02/05/2023] Open
Abstract
The HIV-1 long terminal repeat (LTR) introduced into the macrophage cell line THP-1 and the T lymphocyte cell line Jurkat in association with the luciferase reporter gene is activated by the polar, aprotic solvents dimethylsulfoxide (DMSO), dimethylacetamide (DMAC), and dimethylformamide (DMF). These solvents also greatly potentiated the activation of the LTR in THP-1 cells by phorbol myristate acetate (PMA), tumor necrosis factor alpha (TNF-alpha), H202, and a Staphylococcus epidermidis product. Lipopolysaccharide (LPS) and lipoteichoic acid (LTA) at 1 microg/ml had no effect on the LTR in THP-1 cells unless the solvents were added. The aprotic solvents also greatly potentiated the activation of the LTR in Jurkat cells by PMA, TNF-alpha, and H202, whereas LPS, LTA, or the S. epidermidis product had no effect in the presence or absence of the solvents. DMSO, DMAC, and DMF also increased the production of intact virions by latently HIV-1-infected ACH-2, J1.1, U1, and OM10.1 cells under some experimental conditions. The use of the polar aprotic solvents DMSO, DMAC, and DMF, by amplification, may allow the better detection of a weak activator of the LTR and facilitate studies of the mechanism of activation.
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Affiliation(s)
- S J Klebanoff
- Department of Medicine, University of Washington, Seattle 98195-7185, USA
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24
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Kiener PA, Davis PM, Starling GC, Mehlin C, Klebanoff SJ, Ledbetter JA, Liles WC. Differential induction of apoptosis by Fas-Fas ligand interactions in human monocytes and macrophages. J Exp Med 1997; 185:1511-6. [PMID: 9126933 PMCID: PMC2196275 DOI: 10.1084/jem.185.8.1511] [Citation(s) in RCA: 198] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/1997] [Revised: 02/24/1997] [Indexed: 02/04/2023] Open
Abstract
Human monocytes undergo spontaneous apoptosis upon culture in vitro; removal of serum from the media dramatically increases the rate of this process. Monocyte apoptosis can be significantly abrogated by the addition of growth factors or proinflammatory mediators. We have evaluated the role of the endogenous Fas-Fas ligand (FasL) interaction in the induction of this spontaneous apoptosis and found that a Fas-immunoglobulin (Ig) fusion protein, an antagonistic anti-Fas monoclonal antibody and a rabbit anti-FasL antibody all greatly reduced the onset of apoptosis. The results indicate that spontaneous death of monocytes is mediated via an autocrine or paracrine pathway. Treatment of the cells with growth factors or cytokines that prevented spontaneous apoptosis had no major effects on the expression of Fas or FasL. Additionally, monocyte-derived macrophages were found to express both Fas and FasL but did not undergo spontaneous apoptosis and were not sensitive to stimulation by an agonistic anti-Fas IgM. These results indicate that protective mechanisms in these cells exist at a site downstream of the receptor-ligand interaction.
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Affiliation(s)
- P A Kiener
- Immunological Diseases, Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA
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