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Anti-Proliferative and Cytoprotective Activity of Aryl Carbamate and Aryl Urea Derivatives with Alkyl Groups and Chlorine as Substituents. Molecules 2022; 27:molecules27113616. [PMID: 35684552 PMCID: PMC9182529 DOI: 10.3390/molecules27113616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/24/2022] [Accepted: 05/30/2022] [Indexed: 02/04/2023] Open
Abstract
Natural cytokinines are a promising group of cytoprotective and anti-tumor agents. In this research, we synthesized a set of aryl carbamate, pyridyl urea, and aryl urea cytokinine analogs with alkyl and chlorine substitutions and tested their antiproliferative activity in MDA-MB-231, A-375, and U-87 MG cell lines, and cytoprotective properties in H2O2 and CoCl2 models. Aryl carbamates with the oxamate moiety were selectively anti-proliferative for the cancer cell lines tested, while the aryl ureas were inactive. In the cytoprotection studies, the same aryl carbamates were able to counteract the CoCl2 cytotoxicity by 3–8%. The possible molecular targets of the aryl carbamates during the anti-proliferative action were the adenosine A2 receptor and CDK2. The obtained results are promising for the development of novel anti-cancer therapeutics.
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Kaźmierczak A, Kunikowska A, Doniak M, Kornaś A. Mechanism of kinetin-induced death of Vicia faba ssp. minor root cortex cells. Sci Rep 2021; 11:23746. [PMID: 34887458 PMCID: PMC8660813 DOI: 10.1038/s41598-021-03103-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 11/16/2021] [Indexed: 01/03/2023] Open
Abstract
Cell death (CD) may be induced by endogenous or exogenous factors and contributes to all the steps of plant development. This paper presents results related to the mechanism of CD regulation induced by kinetin (Kin) in the root cortex of Vicia faba ssp. minor. To explain the process, 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55), adenine (Ad), 5'-amine-5'-deoxyadenosine (Ado) and N-(2-chloro-4-piridylo)-N'-phenylurea (CPPU) were applied to (i) block cytokinin receptors (CKs) and inhibit the activities of enzymes of CK metabolism, i.e., (ii) phosphoribosyltransferase, (iii) kinases, and (iv) oxidases, respectively. Moreover, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), lanthanum chloride (LaCl3), ruthenium red (RRed) and cyclosporine A (CS-A) were applied to (i) chelate extracellular calcium ions (Ca2+) as well as blocks of (ii) plasma-, (iii) endoplasmic reticulum- (ER) membrane Ca2+ ion channels and (iv) mitochondria- (MIT) Ca2+ ions release by permeability transition por (PTP), respectively. The measured physiological effectiveness of these factors was the number of living and dying cortex cells estimated with orange acridine (OA) and ethidium bromide (EB), the amounts of cytosolic Ca2+ ions with chlortetracycline (CTC) staining and the intensity of chromatin and Ca2+-CTC complex fluorescence, respectively. Moreover, the role of sorafenib, an inhibitor of RAF kinase, on the vitality of cortex cells and ethylene levels as well as the activities of RAF-like kinase and MEK2 with Syntide-2 and Mek2 as substrates were studied. The results clarified the previously presented suggestion that Kin is converted to appropriate ribotides (5'-monophosphate ribonucleotides), which cooperate with the ethylene and Ca2+ ion signalling pathways to transduce the signal of kinetin-programmed cell death (Kin-PCD). Based on the present and previously published results related to Kin-PCD, the crosstalk between ethylene and MAP kinase signalling, as well as inhibitors of CK receptors and enzymes of their metabolism, is proposed.
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Affiliation(s)
- Andrzej Kaźmierczak
- Department of Cytophysiology, Institute of Experimental Biology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236, Lodz, Poland.
| | - Anita Kunikowska
- Department of Cytophysiology, Institute of Experimental Biology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236, Lodz, Poland
| | - Magdalena Doniak
- Department of Cytophysiology, Institute of Experimental Biology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236, Lodz, Poland
| | - Andrzej Kornaś
- Institute of Biology, Pedagogical University of Krakow, Podchorążych 2, 30-084, Kraków, Poland
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Integrated structural and functional analysis of the protective effects of kinetin against oxidative stress in mammalian cellular systems. Sci Rep 2020; 10:13330. [PMID: 32770053 PMCID: PMC7414151 DOI: 10.1038/s41598-020-70253-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 07/16/2020] [Indexed: 01/04/2023] Open
Abstract
Metabolism and signaling of cytokinins was first established in plants, followed by cytokinin discoveries in all kingdoms of life. However, understanding of their role in mammalian cells is still scarce. Kinetin is a cytokinin that mitigates the effects of oxidative stress in mammalian cells. The effective concentrations of exogenously applied kinetin in invoking various cellular responses are not well standardized. Likewise, the metabolism of kinetin and its cellular targets within the mammalian cells are still not well studied. Applying vitality tests as well as comet assays under normal and hyper-oxidative states, our analysis suggests that kinetin concentrations of 500 nM and above cause cytotoxicity as well as genotoxicity in various cell types. However, concentrations below 100 nM do not cause any toxicity, rather in this range kinetin counteracts oxidative burst and cytotoxicity. We focus here on these effects. To get insights into the cellular targets of kinetin mediating these pro-survival functions and protective effects we applied structural and computational approaches on two previously testified targets for these effects. Our analysis deciphers vital residues in adenine phosphoribosyltransferase (APRT) and adenosine receptor (A2A-R) that facilitate the binding of kinetin to these two important human cellular proteins. We finally discuss how the therapeutic potential of kinetin against oxidative stress helps in various pathophysiological conditions.
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Jiang K, Asami T. Chemical regulators of plant hormones and their applications in basic research and agriculture*. Biosci Biotechnol Biochem 2018; 82:1265-1300. [DOI: 10.1080/09168451.2018.1462693] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
ABSTRACT
Plant hormones are small molecules that play versatile roles in regulating plant growth, development, and responses to the environment. Classic methodologies, including genetics, analytic chemistry, biochemistry, and molecular biology, have contributed to the progress in plant hormone studies. In addition, chemical regulators of plant hormone functions have been important in such studies. Today, synthetic chemicals, including plant growth regulators, are used to study and manipulate biological systems, collectively referred to as chemical biology. Here, we summarize the available chemical regulators and their contributions to plant hormone studies. We also pose questions that remain to be addressed in plant hormone studies and that might be solved with the help of chemical regulators.
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Affiliation(s)
- Kai Jiang
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Tadao Asami
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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Klimeš P, Turek D, Mazura P, Gallová L, Spíchal L, Brzobohatý B. High Throughput Screening Method for Identifying Potential Agonists and Antagonists of Arabidopsis thaliana Cytokinin Receptor CRE1/AHK4. FRONTIERS IN PLANT SCIENCE 2017. [PMID: 28642766 PMCID: PMC5463364 DOI: 10.3389/fpls.2017.00947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The CRE1/AHK4 cytokinin receptor is an important component of plants' hormone signaling systems, and compounds that can alter its activity have potential utility for studying the receptor's functions and/or developing new plant growth regulators. A high throughput method was developed for screening compounds with agonist or antagonist properties toward the CRE1/AHK4 cytokinin receptor in a single experiment using the Nanodrop II liquid handling system and 384-well plates. Potential ligands are screened directly, using a reporter system in which receptor signaling activity triggers expression of β-galactosidase in Escherichia coli. This enzyme generates a fluorescent product from a non-fluorescent substrate, allowing the agonistic/antagonistic behavior of tested compounds to be assayed in relation to that of an internal standard (here the natural ligand, trans-zeatin). The method includes a robust control procedure to determine false positive or false negative effects of the tested compounds arising from their fluorescent or fluorescent-quenching properties. The presented method enables robust, automated screening of large libraries of compounds for ability to activate or inhibit the Arabidopsis thaliana cytokinin receptor CRE1/AHK4.
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Affiliation(s)
- Pavel Klimeš
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR v.v.i. and Central European Institute of Technology, Mendel University in BrnoBrno, Czechia
| | - Dušan Turek
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR v.v.i. and Central European Institute of Technology, Mendel University in BrnoBrno, Czechia
| | - Pavel Mazura
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR v.v.i. and Central European Institute of Technology, Mendel University in BrnoBrno, Czechia
- *Correspondence: Pavel Mazura,
| | - Lucia Gallová
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, OlomoucOlomouc, Czechia
| | - Lukáš Spíchal
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, OlomoucOlomouc, Czechia
| | - Břetislav Brzobohatý
- Laboratory of Plant Molecular Biology, Institute of Biophysics AS CR v.v.i. and Central European Institute of Technology, Mendel University in BrnoBrno, Czechia
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Rigal A, Ma Q, Robert S. Unraveling plant hormone signaling through the use of small molecules. FRONTIERS IN PLANT SCIENCE 2014; 5:373. [PMID: 25126092 PMCID: PMC4115670 DOI: 10.3389/fpls.2014.00373] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/11/2014] [Indexed: 05/03/2023]
Abstract
Plants have acquired the capacity to grow continuously and adjust their morphology in response to endogenous and external signals, leading to a high architectural plasticity. The dynamic and differential distribution of phytohormones is an essential factor in these developmental changes. Phytohormone perception is a fast but complex process modulating specific developmental reprogramming. In recent years, chemical genomics or the use of small molecules to modulate target protein function has emerged as a powerful strategy to study complex biological processes in plants such as hormone signaling. Small molecules can be applied in a conditional, dose-dependent and reversible manner, with the advantage of circumventing the limitations of lethality and functional redundancy inherent to traditional mutant screens. High-throughput screening of diverse chemical libraries has led to the identification of bioactive molecules able to induce plant hormone-related phenotypes. Characterization of the cognate targets and pathways of those molecules has allowed the identification of novel regulatory components, providing new insights into the molecular mechanisms of plant hormone signaling. An extensive structure-activity relationship (SAR) analysis of the natural phytohormones, their designed synthetic analogs and newly identified bioactive molecules has led to the determination of the structural requirements essential for their bioactivity. In this review, we will summarize the so far identified small molecules and their structural variants targeting specific phytohormone signaling pathways. We will highlight how the SAR analyses have enabled better interrogation of the molecular mechanisms of phytohormone responses. Finally, we will discuss how labeled/tagged hormone analogs can be exploited, as compelling tools to better understand hormone signaling and transport mechanisms.
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Affiliation(s)
| | | | - Stéphanie Robert
- *Correspondence: Stéphanie Robert, Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden e-mail:
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Aremu AO, Bairu MW, Novák O, Plačková L, Zatloukal M, Doležal K, Finnie JF, Strnad M, Van Staden J. Physiological responses and endogenous cytokinin profiles of tissue-cultured 'Williams' bananas in relation to roscovitine and an inhibitor of cytokinin oxidase/dehydrogenase (INCYDE) treatments. PLANTA 2012; 236:1775-90. [PMID: 22886380 DOI: 10.1007/s00425-012-1721-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 07/16/2012] [Indexed: 05/11/2023]
Abstract
The effect of supplementing either meta-topolin (mT) or N(6)-benzyladenine (BA) requiring cultures with roscovitine (6-benzylamino-2-[1(R)-(hydroxymethyl)propyl]amino-9-isopropylpurine), a cyclin-dependent kinase (CDK) and N-glucosylation inhibitor, and INCYDE (2-chloro-6-(3-methoxyphenyl)aminopurine), an inhibitor of cytokinin (CK) degradation, on the endogenous CK profiles and physiology of banana in vitro was investigated. Growth parameters including multiplication rate and biomass were recorded after 42 days. Endogenous CK levels were quantified using UPLC-MS/MS while the photosynthetic pigment and phenolic contents were evaluated spectrophotometrically. The highest regeneration rate (93 %) was observed in BA + roscovitine while mT + INCYDE plantlets produced most shoots. Treatment with BA + roscovitine had the highest shoot length and biomass. Although not significant, there was a higher proanthocyanidin level in BA + roscovitine treatments compared to the control (BA). The levels of total phenolics and flavonoids were significantly higher in mT + roscovitine treatment than in the mT-treated regenerants. The presence of roscovitine and/or INCYDE had no significant effect on the photosynthetic pigments of the banana plantlets. Forty-seven aromatic and isoprenoid CKs categorized into nine CK-types were detected at varying concentrations. The presence of mT + roscovitine and/or INCYDE increased the levels of O-glucosides while 9-glucosides were higher in the presence of BA. Generally, the underground parts had higher CK levels than the aerial parts; however, the presence of INCYDE increased the level of CK quantified in the aerial parts. From a practical perspective, the use of roscovitine and INCYDE in micropropagation could be crucial in the alleviation of commonly observed in vitro-induced physiological abnormalities.
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Affiliation(s)
- Adeyemi O Aremu
- Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa
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Krivosheev DM, Kolyachkina SV, Mikhailov SN, Tararov VI, Vanyushin BF, Romanov GA. N6-(benzyloxymethyl)adenosine is a novel anticytokinin, an antagonist of cytokinin receptor CRE1/AHK4 of Arabidopsis. DOKL BIOCHEM BIOPHYS 2012; 444:178-81. [DOI: 10.1134/s1607672912030155] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Indexed: 11/23/2022]
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Lee YC, Yang YC, Huang CL, Kuo TY, Lin JH, Yang DM, Huang NK. When cytokinin, a plant hormone, meets the adenosine A2A receptor: a novel neuroprotectant and lead for treating neurodegenerative disorders? PLoS One 2012; 7:e38865. [PMID: 22719969 PMCID: PMC3377719 DOI: 10.1371/journal.pone.0038865] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 05/11/2012] [Indexed: 11/18/2022] Open
Abstract
It is well known that cytokinins are a class of phytohormones that promote cell division in plant roots and shoots. However, their targets, biological functions, and implications in mammalian systems have rarely been examined. In this study, we show that one cytokinin, zeatin riboside, can prevent pheochromocytoma (PC12) cells from serum deprivation-induced apoptosis by acting on the adenosine A(2A) receptor (A(2A)-R), which was blocked by an A(2A)-R antagonist and a protein kinase A (PKA) inhibitor, demonstrating the functional ability of zeatin riboside by mediating through A(2A)-R signaling event. Since the A(2A)-R was implicated as a therapeutic target in treating Huntington's disease (HD), a cellular model of HD was applied by transfecting mutant huntingtin in PC12 cells. By using filter retardation assay and confocal microscopy we found that zeatin riboside reversed mutant huntingtin (Htt)-induced protein aggregations and proteasome deactivation through A(2A)-R signaling. PKA inhibitor blocked zeatin riboside-induced suppression of mutant Htt aggregations. In addition, PKA activated proteasome activity and reduced mutant Htt protein aggregations. However, a proteasome inhibitor blocked both zeatin riboside-and PKA activator-mediated suppression of mutant Htt aggregations, confirming mediation of the A(2A)-R/PKA/proteasome pathway. Taken together, zeatin riboside might have therapeutic potential as a novel neuroprotectant and a lead for treating neurodegenerative disorders.
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Affiliation(s)
- Yi-Chao Lee
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Ying-Chen Yang
- Department of Animal Science, National Ilan University, Ilan, Taiwan, Republic of China
| | - Chuen-Lin Huang
- Medical Research Center, Cardinal Tien Hospital, Hsintien, New Taipei City, Taiwan, Republic of China
- Graduate Institute of Physiology and Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Tsun-Yung Kuo
- Department of Animal Science, National Ilan University, Ilan, Taiwan, Republic of China
- Institute of Biotechnology, National Ilan University, Ilan, Taiwan, Republic of China
| | - Jung-Hsin Lin
- School of Pharmacy, National Taiwan University, Taipei, Taiwan, Republic of China
- Division of Mechanics, Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
| | - De-Ming Yang
- Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan, Republic of China
| | - Nai-Kuei Huang
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan, Republic of China
- National Research Institute of Chinese Medicine, Taipei, Taiwan, Republic of China
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Heyl A, Riefler M, Romanov GA, Schmülling T. Properties, functions and evolution of cytokinin receptors. Eur J Cell Biol 2011; 91:246-56. [PMID: 21561682 DOI: 10.1016/j.ejcb.2011.02.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/17/2011] [Accepted: 02/18/2011] [Indexed: 12/20/2022] Open
Abstract
The discovery of cytokinin receptors of Arabidopsis thaliana ten years ago was a milestone in plant hormone research. Since then, research has yielded insights into the biochemical properties and functions of these sensor histidine kinases. Their affinities to both trans-zeatin and isopentenyladenine are in the low nM range. Cytokinin ribosides, cis-zeatin and thidiazuron were established as compounds with genuine cytokinin activity and the first cytokinin antagonists were identified. Numerous functions of cytokinin receptors in plant development, as well as in the plant's responses to the environment, have been elucidated and are summarized. Finally, we address the question how the receptors have evolved during plant evolution.
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Affiliation(s)
- Alexander Heyl
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany
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Arata Y, Nagasawa-Iida A, Uneme H, Nakajima H, Kakimoto T, Sato R. The phenylquinazoline compound S-4893 is a non-competitive cytokinin antagonist that targets Arabidopsis cytokinin receptor CRE1 and promotes root growth in Arabidopsis and rice. PLANT & CELL PHYSIOLOGY 2010; 51:2047-59. [PMID: 21047814 DOI: 10.1093/pcp/pcq163] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We identified two phenylquinazoline compounds in a large-scale screening for cytokinin antagonists in yeast expressing the Arabidopsis cytokinin receptor cytokinin response 1/histidine kinase 4 (CRE1). After chemical modifications, we obtained compound S-4893, which non-competitively inhibited binding of the natural ligand 2-isopentenyladenine to CRE1. S-4893 antagonized cytokinin-induced activation of the Arabidopsis response regulator 5 promoter in Arabidopsis. Importantly, S-4893 had no detectable intrinsic cytokinin agonist activity in Arabidopsis or in the transformed yeast system. Cytokinin bioassay further demonstrated that S-4893 antagonized cytokinin-induced stimulation of callus formation and inhibition of root elongation. S-4893 also promoted seminal, crown and lateral root growth in rice, suggesting that S-4893 could potentially promote root growth in a variety of agronomically important plants. We believe S-4893 will be a useful tool in functional studies of cytokinin action in a wide range of plants and a lead compound for the development of useful root growth promoters in agriculture.
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Affiliation(s)
- Yuto Arata
- Agricultural Chemicals Research Laboratory, Sumitomo Chemical Company Limited, Takarazuka, Hyogo, 665-8555 Japan.
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Nisler J, Zatloukal M, Popa I, Dolezal K, Strnad M, Spíchal L. Cytokinin receptor antagonists derived from 6-benzylaminopurine. PHYTOCHEMISTRY 2010; 71:823-30. [PMID: 20189204 DOI: 10.1016/j.phytochem.2010.01.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 01/27/2010] [Accepted: 01/29/2010] [Indexed: 05/08/2023]
Abstract
Recently we reported 6-(2-hydroxy-3-methylbenzylamino)purine (PI-55) as the first molecule to antagonize cytokinin activity at the receptor level. Here we report the synthesis and in vitro biological testing of eleven BAP derivatives substituted in the benzyl ring and in the C2, N7 and N9 positions of the purine moiety. The ability of the compounds to interact with Arabidopsis cytokinin receptors AHK3 and CRE1/AHK4 was tested in bacterial receptor and in live-cell binding assays, and in an Arabidopsis ARR5:GUS (Arabidopsis response regulator 5) reporter gene assay. Cytokinin activity of the compounds was determined in classical cytokinin biotests (tobacco callus, wheat leaf senescence and Amaranthus bioassays). 6-(2,5-Dihydroxybenzylamino)purine (LGR-991) was identified as a cytokinin receptor antagonist. At the molecular level LGR-991 blocks the cytokinin receptor CRE1/AHK4 with the same potency as PI-55. Moreover, LGR-991 acts as a competitive inhibitor of AHK3, and importantly shows reduced agonistic effects in comparison to PI-55 in the ARR5:GUS reporter gene assay and in cytokinin bioassays. LGR-991 causes more rapid germination of Arabidopsis seeds and increases hypocotyl length of dark-grown seedlings, which are characteristics of plants with a reduced cytokinin status. LGR-991 exhibits a structural motive that might lead to preparation of cytokinin antagonists with a broader specificity and reduced agonistic properties.
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Affiliation(s)
- Jaroslav Nisler
- Laboratory of Growth Regulators, Institute of Experimental Botany, AS CR & Palacký University, Olomouc, Czech Republic
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Werner T, Schmülling T. Cytokinin action in plant development. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:527-38. [PMID: 19740698 DOI: 10.1016/j.pbi.2009.07.002] [Citation(s) in RCA: 376] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 07/13/2009] [Indexed: 05/20/2023]
Abstract
Cytokinin regulates many important aspects of plant development in aerial and subterranean organs. The hormone is part of an intrinsic genetic network controlling organ development and growth in these two distinct environments that plants have to cope with. Cytokinin also mediates the responses to variable extrinsic factors, such as light conditions in the shoot and availability of nutrients and water in the root, and has a role in the response to biotic and abiotic stress. Together, these activities contribute to the fine-tuning of quantitative growth regulation in plants. We review recent progress in understanding the cytokinin system and its links to the regulatory pathways that respond to internal and external signals.
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Affiliation(s)
- Tomás Werner
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences (DCPS), Freie Universität Berlin, Albrecht-Thaer-Weg 6, D-14195 Berlin, Germany.
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Depuydt S, De Veylder L, Holsters M, Vereecke D. Eternal youth, the fate of developing Arabidopsis leaves upon Rhodococcus fascians infection. PLANT PHYSIOLOGY 2009; 149:1387-98. [PMID: 19118126 PMCID: PMC2649406 DOI: 10.1104/pp.108.131797] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 12/25/2008] [Indexed: 05/20/2023]
Abstract
The phytopathogenic actinomycete Rhodococcus fascians induces neoplastic shooty outgrowths on infected hosts. Upon R. fascians infection of Arabidopsis (Arabidopsis thaliana), leaves are formed with small narrow lamina and serrated margins. These symptomatic leaves exhibit reduced tissue differentiation, display more but smaller cells that do not endoreduplicate, and accumulate in the G1 phase of the cell cycle. Together, these features imply that leaf growth occurs primarily through mitotic cell division and not via cell expansion. Molecular analysis revealed that cell cycle gene expression is activated continuously throughout symptomatic leaf development, ensuring persistent mitotic cycling and inhibition of cell cycle exit. The transition at the two major cell cycle checkpoints is stimulated as a direct consequence of the R. fascians signals. The extremely reduced phenotypical response of a cyclind3;1-3 triple knockout mutant indicates that the D-type cyclin/retinoblastoma/E2F transcription factor pathway, as a major mediator of cell growth and cell cycle progression, plays a key role in symptom development and is instrumental for the sustained G1-to-S and G2-to-M transitions during symptomatic leaf growth.
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Affiliation(s)
- Stephen Depuydt
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Belgium
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Spíchal L, Werner T, Popa I, Riefler M, Schmülling T, Strnad M. The purine derivative PI-55 blocks cytokinin action via receptor inhibition. FEBS J 2008; 276:244-53. [PMID: 19032596 DOI: 10.1111/j.1742-4658.2008.06777.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
One of several potential approaches to study mechanisms of action of biologically active compounds is to develop their agonists and antagonists. In the present study, we report the identification of the first known molecule antagonizing the activity of the plant hormone cytokinin at the receptor level. This compound, 6-(2-hydroxy-3-methylbenzylamino)purine, designated PI-55 in the present study, is structurally closely related to cytokinin 6-benzylaminopurine, but substitutions at specific positions of the aromatic side chain strongly diminished its cytokinin activity and conferred antagonistic properties. PI-55 competitively inhibited the binding of the natural ligand trans-zeatin to the Arabidopsis cytokinin receptors cytokinin response 1 (CRE1)/Arabidopsis histidine kinase (AHK) 4 and AHK3 and repressed induction of the cytokinin response gene ARR5:GUS. Genetic analysis revealed that CRE1/AHK4 is the primary target of PI-55. Cytokinin bioassays also demonstrated the anticytokinin effect of PI-55 in several other species. Furthermore, we show that PI-55 accelerated the germination of Arabidopsis seeds and promoted the root growth and formation of lateral roots, thus phenocopying the known consequences of a lowered cytokinin status and demonstrating its potential to inhibit cytokinin perception in planta. PI-55 is the first example for the targeted development of a cytokinin antagonist and represents an initial step for the preparation of cytokinin antagonists with broad activity and reduced agonistic properties.
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Affiliation(s)
- Lukás Spíchal
- Laboratory of Growth Regulators, Institute of Experimental Botany, AS CR & Palacký University, Olomouc, Czech Republic.
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