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Swingle MR, Honkanen RE. Inhibitors of Serine/Threonine Protein Phosphatases: Biochemical and Structural Studies Provide Insight for Further Development. Curr Med Chem 2019; 26:2634-2660. [PMID: 29737249 PMCID: PMC10013172 DOI: 10.2174/0929867325666180508095242] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/05/2018] [Accepted: 03/29/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The reversible phosphorylation of proteins regulates many key functions in eukaryotic cells. Phosphorylation is catalyzed by protein kinases, with the majority of phosphorylation occurring on side chains of serine and threonine residues. The phosphomonoesters generated by protein kinases are hydrolyzed by protein phosphatases. In the absence of a phosphatase, the half-time for the hydrolysis of alkyl phosphate dianions at 25º C is over 1 trillion years; knon ~2 x 10-20 sec-1. Therefore, ser/thr phosphatases are critical for processes controlled by reversible phosphorylation. METHODS This review is based on the literature searched in available databases. We compare the catalytic mechanism of PPP-family phosphatases (PPPases) and the interactions of inhibitors that target these enzymes. RESULTS PPPases are metal-dependent hydrolases that enhance the rate of hydrolysis ([kcat/kM]/knon ) by a factor of ~1021, placing them among the most powerful known catalysts on earth. Biochemical and structural studies indicate that the remarkable catalytic proficiencies of PPPases are achieved by 10 conserved amino acids, DXH(X)~26DXXDR(X)~20- 26NH(X)~50H(X)~25-45R(X)~30-40H. Six act as metal-coordinating residues. Four position and orient the substrate phosphate. Together, two metal ions and the 10 catalytic residues position the phosphoryl group and an activated bridging water/hydroxide nucleophile for an inline attack upon the substrate phosphorous atom. The PPPases are conserved among species, and many structurally diverse natural toxins co-evolved to target these enzymes. CONCLUSION Although the catalytic site is conserved, opportunities for the development of selective inhibitors of this important group of metalloenzymes exist.
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Affiliation(s)
- Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
| | - Richard E Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
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Chattopadhyay D, Swingle MR, Salter EA, Wood E, D'Arcy B, Zivanov C, Abney K, Musiyenko A, Rusin SF, Kettenbach A, Yet L, Schroeder CE, Golden JE, Dunham WH, Gingras AC, Banerjee S, Forbes D, Wierzbicki A, Honkanen RE. Crystal structures and mutagenesis of PPP-family ser/thr protein phosphatases elucidate the selectivity of cantharidin and novel norcantharidin-based inhibitors of PP5C. Biochem Pharmacol 2016; 109:14-26. [PMID: 27002182 DOI: 10.1016/j.bcp.2016.03.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 03/15/2016] [Indexed: 12/24/2022]
Abstract
Cantharidin is a natural toxin and an active constituent in a traditional Chinese medicine used to treat tumors. Cantharidin acts as a semi-selective inhibitor of PPP-family ser/thr protein phosphatases. Despite sharing a common catalytic mechanism and marked structural similarity with PP1C, PP2AC and PP5C, human PP4C was found to be insensitive to the inhibitory activity of cantharidin. To explore the molecular basis for this selectivity, we synthesized and tested novel C5/C6-derivatives designed from quantum-based modeling of the interactions revealed in the co-crystal structures of PP5C in complex with cantharidin. Structure-activity relationship studies and analysis of high-resolution (1.25Å) PP5C-inhibitor co-crystal structures reveal close contacts between the inhibitor bridgehead oxygen and both a catalytic metal ion and a non-catalytic phenylalanine residue, the latter of which is substituted by tryptophan in PP4C. Quantum chemistry calculations predicted that steric clashes with the bulkier tryptophan side chain in PP4C would force all cantharidin-based inhibitors into an unfavorable binding mode, disrupting the strong coordination of active site metal ions observed in the PP5C co-crystal structures, thereby rendering PP4C insensitive to the inhibitors. This prediction was confirmed by inhibition studies employing native human PP4C. Mutation of PP5C (F446W) and PP1C (F257W), to mimic the PP4C active site, resulted in markedly suppressed sensitivity to cantharidin. These observations provide insight into the structural basis for the natural selectivity of cantharidin and provide an avenue for PP4C deselection. The novel crystal structures also provide insight into interactions that provide increased selectivity of the C5/C6 modifications for PP5C versus other PPP-family phosphatases.
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Affiliation(s)
| | - Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Edward A Salter
- Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Eric Wood
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA; Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Brandon D'Arcy
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Catherine Zivanov
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA; Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Kevin Abney
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Alla Musiyenko
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Scott F Rusin
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Arminja Kettenbach
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA; Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Larry Yet
- Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Chad E Schroeder
- Department of Medicinal Chemistry, University of Kansas Specialized Chemistry Center, Lawrence, KS 66047, USA
| | - Jennifer E Golden
- Department of Medicinal Chemistry, University of Kansas Specialized Chemistry Center, Lawrence, KS 66047, USA
| | - Wade H Dunham
- Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Anne-Claude Gingras
- Centre for Systems Biology, Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada; Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Surajit Banerjee
- Northeastern Collaborative Access Team (NE-CAT) Cornell University, Lemont, IL, USA
| | - David Forbes
- Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Andrzej Wierzbicki
- Department of Chemistry, University of South Alabama, Mobile, AL 36688, USA
| | - Richard E Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA.
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Harizani M, Ioannou E, Roussis V. The Laurencia Paradox: An Endless Source of Chemodiversity. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2016; 102:91-252. [PMID: 27380407 DOI: 10.1007/978-3-319-33172-0_2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nature, the most prolific source of biological and chemical diversity, has provided mankind with treatments for health problems since ancient times and continues to be the most promising reservoir of bioactive chemicals for the development of modern drugs. In addition to the terrestrial organisms that still remain a promising source of new bioactive metabolites, the marine environment, covering approximately 70% of the Earth's surface and containing a largely unexplored biodiversity, offers an enormous resource for the discovery of novel compounds. According to the MarinLit database, more than 27,000 metabolites from marine macro- and microorganisms have been isolated to date providing material and key structures for the development of new products in the pharmaceutical, food, cosmeceutical, chemical, and agrochemical sectors. Algae, which thrive in the euphotic zone, were among the first marine organisms that were investigated as sources of food, nutritional supplements, soil fertilizers, and bioactive metabolites.Red algae of the genus Laurencia are accepted unanimously as one of the richest sources of new secondary metabolites. Their cosmopolitan distribution, along with the chemical variation influenced to a significant degree by environmental and genetic factors, have resulted in an endless parade of metabolites, often featuring multiple halogenation sites.The present contribution, covering the literature until August 2015, offers a comprehensive view of the chemical wealth and the taxonomic problems currently impeding chemical and biological investigations of the genus Laurencia. Since mollusks feeding on Laurencia are, in many cases, bioaccumulating, and utilize algal metabolites as chemical weaponry against natural enemies, metabolites of postulated dietary origin of sea hares that feed on Laurencia species are also included in the present review. Altogether, 1047 secondary metabolites, often featuring new carbocyclic skeletons, have been included.The chapter addresses: (1) the "Laurencia complex", the botanical description and the growth and population dynamics of the genus, as well as its chemical diversity and ecological relations; (2) the secondary metabolites, which are organized according to their chemical structures and are classified into sesquiterpenes, diterpenes, triterpenes, acetogenins, indoles, aromatic compounds, steroids, and miscellaneous compounds, as well as their sources of isolation which are depicted in tabulated form, and (3) the biological activity organized according to the biological target and the ecological functions of Laurencia metabolites.
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Affiliation(s)
- Maria Harizani
- Department of Pharmacognosy and Chemistry of Natural Products, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens, 15771, Greece
| | - Efstathia Ioannou
- Department of Pharmacognosy and Chemistry of Natural Products, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens, 15771, Greece.
| | - Vassilios Roussis
- Department of Pharmacognosy and Chemistry of Natural Products, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens, 15771, Greece.
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Sutariya TR, Labana BM, Parmar BD, Parmar NJ, Kant R, Gupta VK. A domino synthetic approach for new, angular pyrazol- and isoxazol-heterocycles using [DBU][Ac] as an effective reaction medium. RSC Adv 2015. [DOI: 10.1039/c5ra00493d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Some new, angular pyrazol- and isoxazol-heterocycles have been synthesized by the reaction of pyrazolone/isoxazolone with typical ketone-based substrates—O-alkenyloxy/alkynyloxy-acetophenones.
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Affiliation(s)
| | | | | | | | - Rajni Kant
- Post Graduate Department of Physics
- University of Jammu
- Jammu Tawi-180006
- India
| | - Vivek K. Gupta
- Post Graduate Department of Physics
- University of Jammu
- Jammu Tawi-180006
- India
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Wang BG, Gloer JB, Ji NY, Zhao JC. Halogenated Organic Molecules of Rhodomelaceae Origin: Chemistry and Biology. Chem Rev 2013; 113:3632-85. [DOI: 10.1021/cr9002215] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bin-Gui Wang
- Key Laboratory of Experimental
Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P. R. China
| | - James B. Gloer
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Nai-Yun Ji
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences,
Yantai 264003, P. R. China
| | - Jian-Chun Zhao
- Key Laboratory of Experimental
Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P. R. China
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Parmar NJ, Pansuriya BR, Barad HA, Parmar BD, Kant R, Gupta VK. Triethylammonium acetate-mediated domino-Knoevenagel-hetero-Diels–Alder reaction: synthesis of some angular polyheterocycles. MONATSHEFTE FUR CHEMIE 2012. [DOI: 10.1007/s00706-012-0873-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Parmar NJ, Pansuriya BR, Labana BM, Sutariya TR, Kant R, Gupta VK. Access to Some Angular Aminochromeno[2,3-c]pyrazole Precursors by a Domino Knoevenagel-hetero-Diels-Alder Reaction. European J Org Chem 2012. [DOI: 10.1002/ejoc.201200751] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Mahdi F, Falkenberg M, Ioannou E, Roussis V, Zhou YD, Nagle DG. Thyrsiferol Inhibits Mitochondrial Respiration and HIF-1 Activation. PHYTOCHEMISTRY LETTERS 2011; 4:75-78. [PMID: 21785662 PMCID: PMC3139250 DOI: 10.1016/j.phytol.2010.09.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The cytotoxic marine red algal metabolite thyrsiferol (1) was found to inhibit hypoxia-induced hypoxia-inducible factor-1 (HIF-1) activation in T47D human breast tumor cells (66% inhibition at 3 μM). Compound 1 also suppressed hypoxic induction of HIF-1 target genes (VEGF, GLUT-1) at the mRNA level, and displayed tumor cell line-selective time-dependent inhibition of cell viability/proliferation. Mechanistic studies revealed that 1 selectively suppressed mitochondrial respiration at Complex I (IC(50) 3 μM). Thyrsiferol represents a prototypical, structurally unique electron transport chain inhibitor. The apparent rotenone-like activity may contribute to the observed cytotoxicity of 1 and play an important role in Laurencia chemical defense.
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Affiliation(s)
- Fakhri Mahdi
- Department of Pharmacognosy, School of Pharmacy, University of Mississippi, University, MS 38677, United States
| | - Miriam Falkenberg
- Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece
- Programa de Pós-graduação em Farmácia, Universidade Federal de Santa Catarina, Campus Trindade, 88040-970 Florianópolis, Brazil
| | - Efstathia Ioannou
- Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece
| | - Vassilios Roussis
- Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece
| | - Yu-Dong Zhou
- Department of Pharmacognosy, School of Pharmacy, University of Mississippi, University, MS 38677, United States
| | - Dale G. Nagle
- Department of Pharmacognosy, School of Pharmacy, University of Mississippi, University, MS 38677, United States
- Research Institute of Pharmaceutical Sciences, University of Mississippi, University, MS 38677, United States
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9
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Clausen DJ, Wan S, Floreancig PE. Total synthesis of the protein phosphatase 2A inhibitor lactodehydrothyrsiferol. Angew Chem Int Ed Engl 2011; 50:5178-81. [PMID: 21520363 PMCID: PMC3140912 DOI: 10.1002/anie.201007757] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 03/15/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Dane J. Clausen
- Department of Chemistry, University of Pittsburgh Pittsburgh, Pennsylvania 15260 (USA)
| | - Shuangyi Wan
- Department of Chemistry, University of Pittsburgh Pittsburgh, Pennsylvania 15260 (USA)
| | - Paul E. Floreancig
- Department of Chemistry, University of Pittsburgh Pittsburgh, Pennsylvania 15260 (USA)
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10
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Pereira SR, Vasconcelos VM, Antunes A. The phosphoprotein phosphatase family of Ser/Thr phosphatases as principal targets of naturally occurring toxins. Crit Rev Toxicol 2011; 41:83-110. [PMID: 21288162 DOI: 10.3109/10408444.2010.515564] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Phosphoprotein phosphatases (PPPs) constitute one of three otherwise unrelated families of enzymes that specialize in removing the phosphate group from phosphorylated serine and threonine residues. The involvement of PPP enzymes in the regulation of processes such as gene expression, DNA replication, morphogenesis, synaptic transmission, glycogen metabolism, and apoptosis has underscored their potential as targets for the treatment of a variety of conditions such as cancer, diabetes, or Alzheimer's disease. Interestingly, PPP enzymes also constitute the physiological target of multiple naturally occurring toxins, including microcystins from cyanobacteria and cantharidin from beetles. This review is devoted to the PPP family of enzymes--with a focus on the human PPPs--and the naturally occurring toxins that are known to potently impair their activity. The interaction of the toxins with the enzymes is evaluated in atomic detail to obtain insight on two complementary aspects: (1) which specific structural differences within the similarly folded catalytic core of the PPP enzymes explain their diverse sensitivities to toxin inhibition and (2) which structural features presented by the various toxins account for the differential inhibitory potency towards each PPP. These analyses take advantage of numerous site-directed mutagenesis studies, structure-activity evaluations, and recent crystallographic structures of PPPs bound to different toxins.
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Affiliation(s)
- Susana R Pereira
- CIIMAR/CIMAR-LA, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Porto, Portugal.
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11
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Clausen DJ, Wan S, Floreancig PE. Total Synthesis of the Protein Phosphatase 2A Inhibitor Lactodehydrothyrsiferol. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201007757] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Wada SI, Usami I, Umezawa Y, Inoue H, Ohba SI, Someno T, Kawada M, Ikeda D. Rubratoxin A specifically and potently inhibits protein phosphatase 2A and suppresses cancer metastasis. Cancer Sci 2010; 101:743-50. [PMID: 20028386 PMCID: PMC11158319 DOI: 10.1111/j.1349-7006.2009.01438.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although cytostatin analog protein phosphatase 2A (PP2A)-specific inhibitors are promising candidates of a new type of anticancer drug, their development has been hindered because of their liability. To find new classes of PP2A-specific inhibitors, we conducted a screening with microbial metabolites and found that rubratoxin A, a classical mycotoxin, is a highly specific and potent inhibitor of the enzyme. While rubratoxin A inhibits PP2A at Ki = 28.7 nm, it hardly inhibited any other phosphatases examined. Rubratoxin B, a close analog, also specifically but weakly inhibits PP2A at Ki = 3.1 microM. The inhibition of intracellular PP2A in cultured cells is obviously observed with 20 microM rubratoxin A treatment for 3 h, inducing the overphosphorylation in PP2A substrate proteins. Although rubratoxins and cytostatin differ in the apparent structures, these compounds share similarities in the structures in detail and PP2A-binding manners. Rubratoxin A showed higher suppression of tumor metastasis and reduction of the primary tumor volume than cytostatin in mouse experiments. As a successor of cytostatin analogs, rubratoxin A should be a good compound leading to the development of antitumor drugs targeting PP2A.
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Affiliation(s)
- Shun-ichi Wada
- Numazu Bio-Medical Research Institute, Microbial Chemistry Research Foundation, Shizuoka
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13
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Trygstad TM, Pang Y, Forsyth CJ. Versatile synthesis of the C3-C14 domain of 7-deoxyokadaic acid. J Org Chem 2009; 74:910-3. [PMID: 19072579 DOI: 10.1021/jo8017457] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Described is a flexible synthesis of the C3-C14 domain of 7-deoxyokadaic acid that is amenable to facile structural diversification. Treatment of ynone 10 under acidic conditions led to net bis-conjugate addition of the latent diol to give the thermodynamically favored spiroketal 27, a versatile intermediate, en route to 7-deoxyokadaic acid and analogs.
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Affiliation(s)
- Timothy M Trygstad
- Department of Chemistry and Physical Sciences, The College of St. Scholastica, Duluth, Minnesota 55811, USA
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14
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Hioki H, Motosue M, Mizutani Y, Noda A, Shimoda T, Kubo M, Harada K, Fukuyama Y, Kodama M. Total synthesis of pseudodehydrothyrsiferol. Org Lett 2009; 11:579-82. [PMID: 19113900 DOI: 10.1021/ol802600n] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An enantioselective total synthesis of pseudodehydrothyrsiferol has been accomplished. The synthetic sequence highlights formation of the highly strained tetrahydropyran C-ring by a Mitsunobu-type S(N)2 reaction with an oxygen nucleophile.
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Affiliation(s)
- Hideaki Hioki
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan
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Contribution of natural inhibitors to the understanding of the PI3K/PDK1/PKB pathway in the insulin-mediated intracellular signaling cascade. Int J Mol Sci 2008; 9:2217-2230. [PMID: 19330070 PMCID: PMC2635620 DOI: 10.3390/ijms9112217] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 11/08/2008] [Accepted: 11/12/2008] [Indexed: 11/17/2022] Open
Abstract
The critical initial steps in insulin action include phosphorylation of adapter proteins and activation of phosphatidylinositol 3-kinase (PI3K). One of important components in this process is a protein called Akt/protein kinase B (PKB). The work of numerous different researchers indicates a role of PKB in regulating insulin-stimulated glucose uptake. The crucial role of lipid second messengers in PKB activation has been dissected through the use of the PI3K-specific inhibitors wortmannin and LY294002. Receptor-activated PI3K synthesizes the lipid second messenger PtdIns[3,4,5]-trisphosphate, leading to the recruitment of PKB to the membrane. Membrane attachment of PKB is mediated by its pleckstrin homology domain binding to PtdIns[3,4,5]-trisphosphate or PtdIns[3,4]-bisphosphate with high affinity. Activation of PKB alpha is then achieved at the plasma membrane by phosphorylation of Thr308 in the activation-loop of the kinase domain and Ser473 in the carboxy-terminal regulatory region, respectively. 3-Phosphoinositide-dependent protein kinase-1 (PDK1) is responsible for T308 phosphorylation. The usage of specific inhibitors and natural compound has significantly contributed to investigate the molecular mechanism of PI3K/PDK1/PKB signaling pathway, leading to the putative therapeutics benefits of patients. This review focuses on the contribution of natural inhibitor or compound in our understanding of the mechanism by which insulin induces, especially in PI3K/PDK1/PKB signaling.
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Synthetic Efforts Toward, and Biological Activity of, Thyrsiferol and Structurally-Related Analogues. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/s1572-5995(08)80003-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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17
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Manzo E, Gavagnin M, Bifulco G, Cimino P, Di Micco S, Ciavatta ML, Guo YW, Cimino G. Aplysiols A and B, squalene-derived polyethers from the mantle of the sea hare Aplysia dactylomela. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.07.055] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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18
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Nishiguchi GA, Graham J, Bouraoui A, Jacobs RS, Little RD. 7,11-epi-thyrsiferol: completion of its synthesis, evaluation of its antimitotic properties, and the further development of an SAR model. J Org Chem 2007; 71:5936-41. [PMID: 16872175 DOI: 10.1021/jo060519z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We (a) describe the completion of a total synthesis of 7,11-epi-thyrsiferol (4), (b) compare the antimitotic activities of thyrsiferol (2), Delta15,28-dehydrothyrsiferol (3), and 7,11-epi-thyrsiferol (4), (c) evaluate the synergistic behavior of the title compound and colchicine to inhibit cell proliferation, and (d) describe the results of conformational searches that provide additional insight concerning the SAR profile of the thyrsiferol family of natural products.
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Affiliation(s)
- Gisele A Nishiguchi
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, USA
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Carter-Franklin JN, Butler A. Vanadium Bromoperoxidase-Catalyzed Biosynthesis of Halogenated Marine Natural Products. J Am Chem Soc 2004; 126:15060-6. [PMID: 15548002 DOI: 10.1021/ja047925p] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Marine red algae (Rhodophyta) are a rich source of bioactive halogenated natural products. The biogenesis of the cyclic halogenated terpene marine natural products, in particular, has attracted sustained interest in part because terpenes are the biogenic precursors of many bioactive metabolites. The first enzymatic asymmetric bromination and cyclization of a terpene, producing marine natural products isolated from red algae, is reported. Vanadium bromoperoxidase (V-BrPO) isolated from marine red algae (species of Laurencia, Plocamium, Corallina) catalyzes the bromination of the sesquiterpene (E)-(+)-nerolidol producing alpha-, beta-, and gamma-snyderol and (+)-3beta-bromo-8-epicaparrapi oxide. alpha-Snyderol, beta-snyderol, and (+)-3beta-bromo-8-epicaparrapi oxide have been isolated from Laurencia obtusa, and each have also been isolated from other species of marine red algae. gamma-Snyderol is a proposed intermediate in other bicyclo natural products. Single diastereomers of beta-snyderol, gamma-snyderol, and mixed diastereomers of (+)-3beta-bromo-8-epicaparrapi oxide (de = 20-25%) are produced in the enzyme reaction, whereas two diastereomers of these compounds are formed in the synthesis with 2,4,4,6-tetrabromocyclohexa-2,5-dienone (TBCO). V-BrPO likely functions by catalyzing the two-electron oxidation of bromide ion by hydrogen peroxide producing a bromonium ion or equivalent in the active site that brominates one face of the terminal olefin of nerolidol. These results establish V-BrPO's role in the biosynthesis of brominated cyclic sesquiterpene structures from marine red algae for the first time.
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Affiliation(s)
- Jayme N Carter-Franklin
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA
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Nagle DG, Zhou YD, Mora FD, Mohammed KA, Kim YP. Mechanism targeted discovery of antitumor marine natural products. Curr Med Chem 2004; 11:1725-56. [PMID: 15279579 PMCID: PMC2908268 DOI: 10.2174/0929867043364991] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Antitumor drug discovery programs aim to identify chemical entities for use in the treatment of cancer. Many strategies have been used to achieve this objective. Natural products have always played a major role in anticancer medicine and the unique metabolites produced by marine organisms have increasingly become major players in antitumor drug discovery. Rapid advances have occurred in the understanding of tumor biology and molecular medicine. New insights into mechanisms responsible for neoplastic disease are significantly changing the general philosophical approach towards cancer treatment. Recently identified molecular targets have created exciting new means for disrupting tumor-specific cell signaling, cell division, energy metabolism, gene expression, drug resistance and blood supply. Such tumor-specific treatments could someday decrease our reliance on traditional cytotoxicity-based chemotherapy and provide new less toxic treatment options with significantly fewer side effects. Novel molecular targets and state-of-the-art, molecular mechanism-based screening methods have revitalized antitumor research and these changes are becoming an ever-increasing component of modern antitumor marine natural products research. This review describes marine natural products identified using tumor-specific mechanism-based assays for regulators of angiogenesis, apoptosis, cell cycle, macromolecule synthesis, mitochondrial respiration, mitosis, multidrug efflux and signal transduction. Special emphasis is placed on natural products directly discovered using molecular mechanism-based screening.
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Affiliation(s)
- Dale G Nagle
- Department of Phamacognosy, National Center for Natural Products Research, and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, Mississippi 38677-1848, USA.
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21
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Steelman LS, Pohnert SC, Shelton JG, Franklin RA, Bertrand FE, McCubrey JA. JAK/STAT, Raf/MEK/ERK, PI3K/Akt and BCR-ABL in cell cycle progression and leukemogenesis. Leukemia 2004; 18:189-218. [PMID: 14737178 DOI: 10.1038/sj.leu.2403241] [Citation(s) in RCA: 499] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The roles of the JAK/STAT, Raf/MEK/ERK and PI3K/Akt signal transduction pathways and the BCR-ABL oncoprotein in leukemogenesis and their importance in the regulation of cell cycle progression and apoptosis are discussed in this review. These pathways have evolved regulatory proteins, which serve to limit their proliferative and antiapoptotic effects. Small molecular weight cell membrane-permeable drugs that target these pathways have been developed for leukemia therapy. One such example is imatinib mesylate, which targets the BCR-ABL kinase as well as a few structurally related kinases. This drug has proven to be effective in the treatment of CML patients. However, leukemic cells have evolved mechanisms to become resistant to this drug. A means to combat drug resistance is to target other prominent signaling components involved in the pathway or to inhibit BCR-ABL by other mechanisms. Treatment of imatinib-resistant leukemia cells with drugs that target Ras (farnysyl transferase inhibitors) or with the protein destabilizer geldanamycin has proven to be a means to inhibit the growth of resistant cells. This review will tie together three important signal transduction pathways involved in the regulation of hematopoietic cell growth and indicate how their expression is dysregulated by the BCR-ABL oncoprotein.
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Affiliation(s)
- L S Steelman
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA
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22
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Chang F, Steelman LS, Lee JT, Shelton JG, Navolanic PM, Blalock WL, Franklin RA, McCubrey JA. Signal transduction mediated by the Ras/Raf/MEK/ERK pathway from cytokine receptors to transcription factors: potential targeting for therapeutic intervention. Leukemia 2003; 17:1263-93. [PMID: 12835716 DOI: 10.1038/sj.leu.2402945] [Citation(s) in RCA: 513] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The Ras/Raf/Mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) cascade couples signals from cell surface receptors to transcription factors, which regulate gene expression. Depending upon the stimulus and cell type, this pathway can transmit signals, which result in the prevention or induction of apoptosis or cell cycle progression. Thus, it is an appropriate pathway to target for therapeutic intervention. This pathway becomes more complex daily, as there are multiple members of the kinase and transcription factor families, which can be activated or inactivated by protein phosphorylation. The diversity of signals transduced by this pathway is increased, as different family members heterodimerize to transmit different signals. Furthermore, additional signal transduction pathways interact with the Raf/MEK/ERK pathway to regulate positively or negatively its activity, or to alter the phosphorylation status of downstream targets. Abnormal activation of this pathway occurs in leukemia because of mutations at Ras as well as genes in other pathways (eg PI3K, PTEN, Akt), which serve to regulate its activity. Dysregulation of this pathway can result in autocrine transformation of hematopoietic cells since cytokine genes such as interleukin-3 and granulocyte/macrophage colony-stimulating factor contain the transacting binding sites for the transcription factors regulated by this pathway. Inhibitors of Ras, Raf, MEK and some downstream targets have been developed and many are currently in clinical trials. This review will summarize our current understanding of the Ras/Raf/MEK/ERK signal transduction pathway and the downstream transcription factors. The prospects of targeting this pathway for therapeutic intervention in leukemia and other cancers will be evaluated.
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Affiliation(s)
- F Chang
- Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27858, USA
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23
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Souto ML, Manríquez CP, Norte M, Leira F, Fernández JJ. The inhibitory effects of squalene-derived triterpenes on protein phosphatase PP2A. Bioorg Med Chem Lett 2003; 13:1261-4. [PMID: 12657259 DOI: 10.1016/s0960-894x(03)00136-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper reports testing 15 polyether triterpenes with a squalene carbon skeleton for inhibitory effects on type 2A protein phosphatase. Two compounds, 16-hydroxydehydrothyrsiferol 10 and thyrsenol B 14, exhibited significant inhibitory action at a concentration of 10 microM. Comparison with thyrsiferyl-23-acetate 1 showed that a similar spatial disposition for the hydroxy group around C-15 or C-16 was the structural feature shared by these metabolites.
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Affiliation(s)
- María L Souto
- Instituto Universitario de Bio-Orgánica, Universidad de La Laguna, Astrofísico Francisco Sánchez 2, 38206 La Laguna, Spain
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24
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Forsyth CJ, Dounay AB, Sabes SF, Urbanek RA. Biotherapeutic potential and synthesis of okadaic acid. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2001:57-102. [PMID: 11077606 DOI: 10.1007/978-3-662-04042-3_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- C J Forsyth
- Department of Chemistry, University of Minnesota, Minneapolis 55455-0431, USA
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26
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Manrı́quez CP, Souto ML, Gavı́n JA, Norte M, Fernández JJ. Several new squalene-derived triterpenes from Laurencia. Tetrahedron 2001. [DOI: 10.1016/s0040-4020(01)00169-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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27
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McCuskey A, Keane MA, Mudgee LM, Sim AT, Sakoff J, Quinn RJ. Anhydride modified cantharidin analogues. Is ring opening important in the inhibition of protein phosphatase 2A? Eur J Med Chem 2000; 35:957-64. [PMID: 11121622 DOI: 10.1016/s0223-5234(00)00186-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A series of anhydride modified cantharidin analogues have been synthesised and screened for their ability to inhibit protein phosphatase 2A. Surprisingly only analogues capable of undergoing a facile ring opening of the anhydride moiety displayed any significant inhibition. Subsequent NMR experiments indicated that 7-oxobicyclo[2.2.1]heptane-2,3-dicarboxylic acid was the major (sole) species under assay conditions. The ability of these modified anhydro-cantharidin analogues to inhibit protein phosphatase 2A varies from 4 (16) to 100% (8) at 100 microM test concentration.
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28
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Herzig S, Neumann J. Effects of serine/threonine protein phosphatases on ion channels in excitable membranes. Physiol Rev 2000; 80:173-210. [PMID: 10617768 DOI: 10.1152/physrev.2000.80.1.173] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review deals with the influence of serine/threonine-specific protein phosphatases on the function of ion channels in the plasma membrane of excitable tissues. Particular focus is given to developments of the past decade. Most of the electrophysiological experiments have been performed with protein phosphatase inhibitors. Therefore, a synopsis is required incorporating issues from biochemistry, pharmacology, and electrophysiology. First, we summarize the structural and biochemical properties of protein phosphatase (types 1, 2A, 2B, 2C, and 3-7) catalytic subunits and their regulatory subunits. Then the available pharmacological tools (protein inhibitors, nonprotein inhibitors, and activators) are introduced. The use of these inhibitors is discussed based on their biochemical selectivity and a number of methodological caveats. The next section reviews the effects of these tools on various classes of ion channels (i.e., voltage-gated Ca(2+) and Na(+) channels, various K(+) channels, ligand-gated channels, and anion channels). We delineate in which cases a direct interaction between a protein phosphatase and a given channel has been proven and where a more complex regulation is likely involved. Finally, we present ideas for future research and possible pathophysiological implications.
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Affiliation(s)
- S Herzig
- Institut für Pharmakologie, Universität Köln, Köln, Germany.
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29
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González IC, Forsyth CJ. Novel synthesis of the C1-C15 polyether domain of the thyrsiferol and venustatriol natural products. Org Lett 1999; 1:319-22. [PMID: 10822569 DOI: 10.1021/ol990648k] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[formula: see text] A convergent construction of the C1-C15 domain of the thyrsiferol-related natural products has been developed. This involved the separate construction of C1-C7 and C8-C15 fragments, their organochromic-mediated coupling, and subsequent reductive closure of the B ring. This synthetic A-B-C ring construct will be useful for the total synthesis of the biologically active polyether squalenoid natural products, as well as their non-natural analogues.
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Affiliation(s)
- I C González
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
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30
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Matsuzawa S, Kawamura T, Mitsuhashi S, Suzuki T, Matsuo Y, Suzuki M, Mizuno Y, Kikuchi K. Thyrsiferyl 23-acetate and its derivatives induce apoptosis in various T- and B-leukemia cells. Bioorg Med Chem 1999; 7:381-7. [PMID: 10218832 DOI: 10.1016/s0968-0896(98)00226-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Thyrsiferyl 23-acetate (TF-23A), a cytotoxic compound from marine red alga, induced a rapid cell death in various leukemic T- and B-cell lines. During incubation of Jurkat cells with TF-23A, condensation and fragmentation of nuclei occurred and clusters composed of uneven small cellular particles were formed. Concentration- and time-dependent DNA fragmentation was also induced by the incubation of the cells with TF-23A. These results demonstrate that the TF-23A-induced cell death follows a typical apoptotic process. The TF-23A-induced apoptosis was prevented by fetal calf serum and insulin, but not by EGF or PDGF. TF-23A and its several analogous compounds showed apoptosis-inducing activity. However, only TF-23A out of these compounds showed an inhibitory activity for protein phosphatase 2A, PP2A. These results strongly suggest that a structure of TF-23A involved in induction of apoptosis is different from that involved in the PP2A inhibition.
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Affiliation(s)
- S Matsuzawa
- Section of Biochemistry, Institute of Immunological Science, Hokkaido University, Sapporo, Japan
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31
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Urbanek RA, Sabes SF, Forsyth CJ. Efficient Synthesis of Okadaic Acid. 1. Convergent Assembly of the C15−C38 Domain. J Am Chem Soc 1998. [DOI: 10.1021/ja973287h] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rebecca A. Urbanek
- Contribution from the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Steven F. Sabes
- Contribution from the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
| | - Craig J. Forsyth
- Contribution from the Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455
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32
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Sheppeck JE, Gauss CM, Chamberlin AR. Inhibition of the Ser-Thr phosphatases PP1 and PP2A by naturally occurring toxins. Bioorg Med Chem 1997; 5:1739-50. [PMID: 9354230 DOI: 10.1016/s0968-0896(97)00146-6] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The okadaic acid class of naturally occurring toxins is a structurally diverse group of molecules that inhibit the protein phosphatases PP1 and PP2A. Studies providing information about the mode of binding between the toxins and the phosphatases contribute to an overall understanding of the signal transduction pathways in which the phosphatases are involved.
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Affiliation(s)
- J E Sheppeck
- Department of Chemistry, University of California at Irvine 92697, USA
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33
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Favre B, Turowski P, Hemmings BA. Differential inhibition and posttranslational modification of protein phosphatase 1 and 2A in MCF7 cells treated with calyculin-A, okadaic acid, and tautomycin. J Biol Chem 1997; 272:13856-63. [PMID: 9153244 DOI: 10.1074/jbc.272.21.13856] [Citation(s) in RCA: 259] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Calyculin-A (CA), okadaic acid (OA), and tautomycin (TAU) are potent inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A) and are widely used on cells in culture. Despite their well characterized selectivity in vitro, their exact intracellular effects on PP1 and PP2A cannot be directly deduced from their extracellular concentration because their cell permeation properties are not known. Here we demonstrate that, due to the tight binding of the inhibitors to PP1 and/or PP2A, their cell penetration could be monitored by measuring PP1 and PP2A activities in cell-free extracts. Treatment of MCF7 cells with 10 nM CA for 2 h simultaneously inhibited PP1 and PP2A activities by more than 50%. A concentration of 1 microM OA was required to obtain a similar time course of PP2A inhibition in MCF7 cells to that observed with 10 nM CA, whereas PP1 activity was unaffected. PP1 was predominantly inhibited in MCF7 cells treated with TAU but even at 10 microM TAU PP1 inhibition was much slower than that observed with 10 nM CA. Furthermore, binding of inhibitors to PP2Ac and/or PP1c in MCF7 cells led to differential posttranslational modifications of the carboxyl termini of the proteins as demonstrated by Western blotting. OA and CA, in contrast to TAU, induced demethylation of the carboxyl-terminal Leu309 residue of PP2Ac. On the other hand, CA and TAU, in contrast to OA, elicited a marked decrease in immunoreactivity of the carboxyl terminus of the alpha-isoform of PP1c, probably reflecting proteolysis of the protein. These results suggest that in MCF7 cells OA selectively inhibits PP2A and TAU predominantly affects PP1, a conclusion supported by their differential effects on cytokeratins in this cell line.
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Affiliation(s)
- B Favre
- Friedrich Miescher-Institut, P. O. Box 2543, CH-4002 Basel, Switzerland
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34
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Wipf P, Cunningham A, Rice RL, Lazo JS. Combinatorial synthesis and biological evaluation of library of small-molecule Ser/Thr-protein phosphatase inhibitors. Bioorg Med Chem 1997; 5:165-77. [PMID: 9043668 DOI: 10.1016/s0968-0896(96)00199-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In eukaryotes, phosphorylation of serine, threonine, and tyrosine residues on proteins is a fundamental posttranslational regulatory process for such functions as signal transduction, gene transcription, RNA splicing, cellular adhesion, apoptosis, and cell cycle control. Based on functional groups present in natural product serine/threonine protein phosphatase (PSTPase) inhibitors, we have designed pharmacophore model 1 and demonstrated the feasibility of a combinatorial chemistry approach for the preparation of functional analogues of 1. Preliminary biological testing of 18 structural variants of 1 has identified two compounds with growth inhibitory activity against cultured human breast cancer cells. In vitro inhibition of the PSTPase PP2A was demonstrated with compound 1d. Using flow cytometry we observed that compound f1 caused prominent inhibition in the G1 phase of the cell cycle. Thus, the combinatorial modifications of the minimal pharmacophore 1 can generate biologically interesting antiproliterative agents.
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Affiliation(s)
- P Wipf
- Department of Chemistry, University of pittsburgh, PA 15260, USA
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35
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Humphrey JM, Aggen JB, Chamberlin AR. Total Synthesis of the Serine-Threonine Phosphatase Inhibitor Microcystin-LA. J Am Chem Soc 1996. [DOI: 10.1021/ja961683e] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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