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The gallium complex KP46 sensitizes resistant leukemia cells and overcomes Bcl-2-induced multidrug resistance in lymphoma cells via upregulation of Harakiri and downregulation of XIAP in vitro. Biomed Pharmacother 2022; 156:113974. [DOI: 10.1016/j.biopha.2022.113974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 10/28/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
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Stein A, Hilken née Thomopoulou P, Frias C, Hopff SM, Varela P, Wilke N, Mariappan A, Neudörfl JM, Fedorov AY, Gopalakrishnan J, Gigant B, Prokop A, Schmalz HG. B-nor-methylene Colchicinoid PT-100 Selectively Induces Apoptosis in Multidrug-Resistant Human Cancer Cells via an Intrinsic Pathway in a Caspase-Independent Manner. ACS OMEGA 2022; 7:2591-2603. [PMID: 35097257 PMCID: PMC8792921 DOI: 10.1021/acsomega.1c04659] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/31/2021] [Indexed: 05/14/2023]
Abstract
Colchicine, the main active alkaloid from Colchicum autumnale L., is a potent tubulin binder and represents an interesting lead structure for the development of potential anticancer chemotherapeutics. We report on the synthesis and investigation of potentially reactive colchicinoids and their surprising biological activities. In particular, the previously undescribed colchicinoid PT-100, a B-ring contracted 6-exo-methylene colchicinoid, exhibits extraordinarily high antiproliferative and apoptosis-inducing effects on various types of cancer cell lines like acute lymphoblastic leukemia (Nalm6), acute myeloid leukemia (HL-60), Burkitt-like lymphoma (BJAB), human melanoma (MelHO), and human breast adenocarcinoma (MCF7) cells at low nanomolar concentrations. Apoptosis induction proved to be especially high in multidrug-resistant Nalm6-derived cancer cell lines, while healthy human leukocytes and hepatocytes were not affected by the concentration range studied. Furthermore, caspase-independent initiation of apoptosis via an intrinsic pathway was observed. PT-100 also shows strong synergistic effects in combination with vincristine on BJAB and Nalm6 cells. Cocrystallization of PT-100 with tubulin dimers revealed its (noncovalent) binding to the colchicine-binding site of β-tubulin at the interface to the α-subunit. A pronounced effect of PT-100 on the cytoskeleton morphology was shown by fluorescence microscopy. While the reactivity of PT-100 as a weak Michael acceptor toward thiols was chemically proven, it remains unclear whether this contributes to the remarkable biological properties of this unusual colchicinoid.
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Affiliation(s)
- Andreas Stein
- Department
of Chemistry, University of Cologne, 50939 Cologne, Germany
| | | | - Corazon Frias
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Sina M. Hopff
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Paloma Varela
- Université
Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the
Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Nicola Wilke
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
| | - Arul Mariappan
- Laboratory
for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | | | - Alexey Yu Fedorov
- Department
of Organic Chemistry, N.I. Lobachevsky State
University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russian
Federation
| | - Jay Gopalakrishnan
- Laboratory
for Centrosome and Cytoskeleton Biology, Institute of Human Genetics, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Benoît Gigant
- Université
Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the
Cell (I2BC), 91198 Gif-sur-Yvette cedex, France
| | - Aram Prokop
- Department
of Paediatric Oncology, Children’s
Hospital Cologne, 50735 Cologne, Germany
- Department
of Pediatric Hematology/Oncology, Helios
Clinic Schwerin, 19055 Schwerin, Germany
- MSH
Medical School Hamburg, Am Kaiserkai 1, 20457 Hamburg, Germany
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Hopff SM, Wang Q, Frias C, Ahrweiler M, Wilke N, Wilke N, Berkessel A, Prokop A. A metal-free salalen ligand with anti-tumor and synergistic activity in resistant leukemia and solid tumor cells via mitochondrial pathway. J Cancer Res Clin Oncol 2021; 147:2591-2607. [PMID: 34213662 PMCID: PMC8310854 DOI: 10.1007/s00432-021-03679-3] [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: 12/03/2020] [Accepted: 05/27/2021] [Indexed: 12/15/2022]
Abstract
PURPOSE Since the discovery of the well-known cis-platin, transition metal complexes are highly recognized as cytostatic agents. However, toxic side effects of the metal ions present in the complexes may pose significant problems for their future development. Therefore, we investigated the metal-free salalen ligand WQF 044. METHODS DNA fragmentations in leukemia (Nalm6) and solid tumor cells (BJAB, MelHO, MCF-7, RM82) proved the apoptotic effects of WQF 044, its overcoming of resistances and the cellular pathways that are affected by the substance. The apoptotic mechanisms finding were supported by western blot analysis, measurement of the mitochondrial membrane potential and polymerase chain reactions. RESULTS A complex intervention in the mitochondrial pathway of apoptosis with a Bcl-2 and caspase dependence was observed. Additionally, a wide range of tumors were affected by the ligand in a low micromolar range in-vitro. The compound overcame multidrug resistances in P-gp over-expressed acute lymphoblastic leukemia and CD95-downregulated Ewing's sarcoma cells. Quite remarkable synergistic effects with vincristine were observed in Burkitt-like lymphoma cells. CONCLUSION The investigation of a metal-free salalen ligand as a potential anti-cancer drug revealed in promising results for a future clinical use.
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Affiliation(s)
- Sina M Hopff
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany.
| | - Qifang Wang
- Department of Chemistry, University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Corazon Frias
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
| | - Marie Ahrweiler
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
| | - Nicola Wilke
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
| | - Nathalie Wilke
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
| | - Albrecht Berkessel
- Department of Chemistry, University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Aram Prokop
- Department of Pediatric Hematology/Oncology, Municipal Clinics of Cologne, Children's Hospital of the City Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
- Department of Pediatric Hematology/Oncology, Helios Clinic Schwerin, Wismarsche Straße 393-397, 19055, Schwerin, Germany
- Medical School Hamburg (MSH), University of Applied Sciences and Medical University, Am Kaiserkai 1, 20457, Hamburg, Germany
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Hopff SM, Onambele LA, Brandenburg M, Berkessel A, Prokop A. Sensitizing multidrug-resistant leukemia cells to common cytostatics by an aluminium-salen complex that has high-apoptotic effects in leukemia, lymphoma and mamma carcinoma cells. Biometals 2021; 34:211-220. [PMID: 33560473 DOI: 10.1007/s10534-020-00273-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 11/18/2020] [Indexed: 11/25/2022]
Abstract
We investigated the aluminium-salen complex MBR-8 as a potential anti-cancer agent. To see apoptotic effects induced by MBR-8, alone and in combination with common cytostatic drugs, DNA-fragmentations were studied using the flow cytometric analysis. Western blot analysis and measurement of the mitochondrial membrane potential with a JC-1 dye were employed to identify the pathway of apoptosis. An impressive overcoming of multidrug-resistance in leukemia (Nalm6) cells was observed. Additionally, solid tumor cells including Burkitt-like lymphoma (BJAB) and mamma carcinoma cells (MCF-7) are affected by MBR-8 in the same way. Western blot analysis revealed activation of caspase-3. MBR-8 showed very pronounced selectivity with regard to tumor cells and high synergistic effects in Nalm6 and daunorubicin-resistant Nalm6 cells when administered in combination with vincristine, daunorubicin and doxorubicin. The aluminium-salen complex MBR-8 showed very promising anti-cancer properties which warrant further development towards a cytostatic agent for future chemotherapy. Studies on aluminium compounds for cancer therapy are rare, and our report adds to this important body of knowledge.
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Affiliation(s)
- Sina M Hopff
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany.
| | - Liliane A Onambele
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
| | - Marc Brandenburg
- Department of Chemistry, Organic Chemistry, University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Albrecht Berkessel
- Department of Chemistry, Organic Chemistry, University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Aram Prokop
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735, Cologne, Germany
- Department of Pediatric Hematology/Oncology, Helios Clinic Schwerin, Wismarsche Straße 393-397, 19055, Schwerin, Germany
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Hopff SM, Onambele LA, Brandenburg M, Berkessel A, Prokop A. Discovery of a cobalt (III) salen complex that induces apoptosis in Burkitt like lymphoma and leukemia cells, overcoming multidrug resistance in vitro. Bioorg Chem 2020; 104:104193. [PMID: 32947134 DOI: 10.1016/j.bioorg.2020.104193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 06/19/2020] [Accepted: 08/02/2020] [Indexed: 01/09/2023]
Abstract
A very small number of cobalt complexes is examined in oncology research. In this work, we investigate the cobalt (III) salen complex MBR-60 that turns out to be a promising anticancer drug. It induces apoptosis in Nalm6 leukemia and BJAB lymphoma cells and overcomes multidrug resistances by blocking the drug efflux pump P-glycoprotein. It further develops the apoptotic effects over the intrinsic pathway. An activation of caspase-3, caspase-8 and caspase-9 can be detected by western blot analysis. The independence of CD95 is shown by similar apoptotic inductions in BJAB and BJAB FADDdn cells. MBR-60 displays synergistic effects with daunorubicin and vincristine and has a selectivity to tumor cells. In comparison to the apoptotic effects of MBR-60 in BJAB lymphoma cells, the cobalt-free ligand 5 does not influence these cells. The research highlights that a cobalt complex has a therapeutic potential for cancer treating with a focus on drug-resistant tumors.
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Affiliation(s)
- Sina M Hopff
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735 Cologne, Germany.
| | - Liliane A Onambele
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735 Cologne, Germany
| | - Marc Brandenburg
- Department of Chemistry, Organic Chemistry, University of Cologne, Greinstraße 4, 50939 Cologne, Germany
| | - Albrecht Berkessel
- Department of Chemistry, Organic Chemistry, University of Cologne, Greinstraße 4, 50939 Cologne, Germany
| | - Aram Prokop
- Department of Pediatric Hematology/Oncology, Children's Hospital Cologne, Amsterdamer Straße 59, 50735 Cologne, Germany; Department of Pediatric Hematology/Oncology, Helios Clinic Schwerin, Wismarsche Straße 393-397, 19055 Schwerin, Germany
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6
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Onambele LA, Koth D, Czaplewska JA, Schubert US, Görls H, Yano S, Obata M, Gottschaldt M, Prokop A. Mitochondrial Mode of Action of a Thymidine-Based Cisplatin Analogue Breaks Resistance in Cancer Cells. Chemistry 2010; 16:14498-505. [DOI: 10.1002/chem.201000785] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Kater B, Hunold A, Schmalz HG, Kater L, Bonitzki B, Jesse P, Prokop A. Iron containing anti-tumoral agents: unexpected apoptosis-inducing activity of a ferrocene amino acid derivative. J Cancer Res Clin Oncol 2010; 137:639-49. [DOI: 10.1007/s00432-010-0924-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Accepted: 05/21/2010] [Indexed: 10/19/2022]
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Jesse P, Mottke G, Eberle J, Seifert G, Henze G, Prokop A. Apoptosis-inducing activity of Helleborus niger in ALL and AML. Pediatr Blood Cancer 2009; 52:464-9. [PMID: 19090543 DOI: 10.1002/pbc.21905] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Helleborus niger is used in the adjuvant treatment of different tumors in anthroposophical medicine. Indications include various types of brain tumors in children, as well as prostate cancer, leukemia and lymphoma. Our aim was to investigate the therapeutic effects of these extracts apart from the traditional use. PROCEDURES : We used an aqueous whole plant extract of H. niger in different cancer and leukemia cell lines and primary cells of patients with childhood ALL and AML and identified the main mechanisms of action. RESULTS A strong inhibition of proliferation is caused by specific apoptosis induction, which is executed via the mitochondrial pathway and caspase-3 processing. Apoptosis could be detected in lymphoma (BJAB), leukemia (Reh, Nalm6, Sup-B15) and melanoma (Mel-HO) cells and overcomes a Bcl-2-mediated block of apoptosis. In primary cells of patients with childhood ALL and AML, which were partly poor responding to doxorubicin and daunorubicin, a strong apoptosis induction was determined. In combination with the vinca alkaloid vincristine, strong synergistic effects were detected in BJAB cells. CONCLUSION We demonstrate in vitro efficacy of H. niger extract in cells of hematological malignancies; these studies should encourage in vivo experiments.
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Affiliation(s)
- Patrick Jesse
- Department of Pediatric Oncology/Hematology, Charité, Universitätsmedizin Berlin, Berlin, Germany.
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Larvor MP, Cerdan R, Gumila C, Maurin L, Seta P, Roustan C, Vial H. Characterization of the lipid-binding domain of the Plasmodium falciparum CTP:phosphocholine cytidylyltransferase through synthetic-peptide studies. Biochem J 2003; 375:653-61. [PMID: 12901716 PMCID: PMC1223718 DOI: 10.1042/bj20031011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Accepted: 08/05/2003] [Indexed: 11/17/2022]
Abstract
Phospholipid biosynthesis plays a key role in malarial infection and is regulated by CCT (CTP:phosphocholine cytidylyltransferase). This enzyme belongs to the group of amphitropic proteins which are regulated by reversible membrane interaction. To assess the role of the putative membrane-binding domain of Plasmodium falciparum CCT (PfCCT), we synthesized three peptides, K21, V20 and K54 corresponding to residues 274-294, 308-327 and 274-327 of PfCCT respectively. Conformational behaviour of the peptides, their ability to bind to liposomes and to destabilize lipid bilayers, and their insertion properties were investigated by different biophysical techniques. The intercalation mechanisms of the peptides were refined further by using surface-pressure measurements on various monolayers at the air/water interface. In the present study, we show that the three studied peptides are able to bind to anionic and neutral phospholipids, and that they present an alpha-helical conformation upon lipid binding. Peptides V20 and the full-length K54 intercalate their hydrophobic parts into an anionic bilayer and, to a lesser extent, a neutral one for V20. Peptide K21 interacts only superficially with both types of phospholipid vesicles. Adsorption experiments performed at the air/water interface revealed that peptide K54 is strongly surface-active in the absence of lipid. Peptide V20 presents an atypical behaviour in the presence of phosphatidylserine. Whatever the initial surface pressure of a phosphatidylserine film, peptide V20 and phosphatidylserine entities seem linked together in a special organization involving electrostatic and hydrophobic interactions. We showed that PfCCT presents different lipid-dependence properties from other studied CCTs. Although the lipid-binding domain seems to be located in the C-terminal region of the enzyme, as with the mammalian counterpart, the membrane anchorage, which plays a key role in the enzyme regulation, is driven by two alpha-helices, which behave differently from one another.
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Affiliation(s)
- Marie-Pierre Larvor
- CNRS (UMR 5539) Laboratoire de Dynamique Moléculaire des Interactions Membranaires, Université Montpellier II, cc 107, Place Eugène Bataillon, 34095 Montpellier, cedex 5, France
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10
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Wieder T, Prokop A, Bagci B, Essmann F, Bernicke D, Schulze-Osthoff K, Dörken B, Schmalz HG, Daniel PT, Henze G. Piceatannol, a hydroxylated analog of the chemopreventive agent resveratrol, is a potent inducer of apoptosis in the lymphoma cell line BJAB and in primary, leukemic lymphoblasts. Leukemia 2001; 15:1735-42. [PMID: 11681415 DOI: 10.1038/sj.leu.2402284] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The stilbene phytochemicals resveratrol and piceatannol have been reported to possess substantial antitumorigenic and antileukemic activities, respectively. Although recent experimental data revealed the proapoptotic potency of resveratrol, the molecular mechanisms underlying the antileukemic activity have not yet been studied in detail. In the present study, we show that resveratrol, as well as the hydroxylated analog piceatannol, are potent inducers of apoptotic cell death in BJAB Burkitt-like lymphoma cells with an ED50 concentration of 25 microM. Further experiments revealed that treatment of BJAB cells with both substances led to a concentration-dependent activation of caspase-3 and mitochondrial permeability transition. Using BJAB cells overexpressing a dominant-negative mutant of the Fas-associated death domain (FADD) adaptor protein to block death receptor-mediated apoptosis, we demonstrate that resveratrol- and piceatannol-induced cell death in these cells is independent of the CD95/Fas signaling pathway. To explore the antileukemic properties of both compounds in more detail, we extended our study to primary, leukemic lymphoblasts. Interestingly, piceatannol but not resveratrol is a very efficient inducer of apoptosis in this ex vivo assay with leukemic lymphoblasts of 21 patients suffering from childhood lymphoblastic leukemia (ALL).
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Affiliation(s)
- T Wieder
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University of Berlin, Germany
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Friedrich K, Wieder T, Von Haefen C, Radetzki S, Jänicke R, Schulze-Osthoff K, Dörken B, Daniel PT. Overexpression of caspase-3 restores sensitivity for drug-induced apoptosis in breast cancer cell lines with acquired drug resistance. Oncogene 2001; 20:2749-60. [PMID: 11420687 DOI: 10.1038/sj.onc.1204342] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2000] [Revised: 12/01/2000] [Accepted: 02/06/2001] [Indexed: 01/11/2023]
Abstract
In this study, we asked whether overexpression of caspase-3, a central downstream executioner of apoptotic pathways, might sensitize breast cancer cells with acquired drug resistance (MT1/ADR) to drug-induced apoptosis. As control, we employed caspase-3 negative and caspase-3-transfected MCF-7 cells. Whereas mock-transfected MCF-7 cells were resistant to epirubicin, etoposide and paclitaxel (taxol), the same drugs led to breakdown of nuclear DNA in caspase-3-transfected MCF-7 cells. MT1/ADR cells express low levels of wild type caspase-3 but show defective caspase activation and apoptosis upon drug exposure. These cells also display a less efficient activation of the mitochondrial permeability transition. Caspase-3-transfected MT1/ADR clones showed a 2.8-fold increase in the protein level and a 3.7-fold higher specific enzyme activity. Procaspase-3 overexpression was not toxic and did not affect background apoptosis. Interestingly, procaspase-3-transfected MT1/ADR cells were more sensitive to cytotoxic drugs as compared with vector-transfected controls and DNA fragmentation nearly reached the levels of the original drug sensitive MT1 cells. Thus, overexpression of caspase-3 enhances chemosensitivity especially in situations where activation of the mitochondrial apoptosome is disturbed.
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Affiliation(s)
- K Friedrich
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University Berlin, 13125 Berlin, Germany
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12
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Wieder T, Essmann F, Prokop A, Schmelz K, Schulze-Osthoff K, Beyaert R, Dörken B, Daniel PT. Activation of caspase-8 in drug-induced apoptosis of B-lymphoid cells is independent of CD95/Fas receptor-ligand interaction and occurs downstream of caspase-3. Blood 2001; 97:1378-87. [PMID: 11222383 DOI: 10.1182/blood.v97.5.1378] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activation of caspase-8, a crucial upstream mediator of death receptor signaling, was investigated in epirubicin- and Taxol-induced apoptosis of B-lymphoma cells. This study was performed because the CD95/Fas receptor-ligand interaction, recruitment of the Fas-associated death domain (FADD) adaptor protein, and subsequent activation of procaspase-8 have been implicated in the execution of drug-induced apoptosis in other cell types. Indeed, active caspase-8 was readily detected after treatment of mature and immature B-lymphoid cells with epirubicin or Taxol. However, neither constitutive nor drug-induced expression of the CD95/Fas ligand was detectable in B-lymphoma cells. Furthermore, overexpression of a dominant-negative FADD mutant (FADDdn) did not block caspase-8 processing and subsequent DNA fragmentation, indicating that drug-induced caspase-8 activation was mediated by a CD95/Fas-independent mechanism. Instead, caspase-8 cleavage was slightly preceded by activation of caspase-3, suggesting that drug-induced caspase-8 activation in B-lymphoma cells is a downstream event mediated by other caspases. This assumption was confirmed in 2 experimental systems-zDEVD-fmk, a cell-permeable inhibitor of caspase-3-like activity, blocked drug-induced caspase-8 cleavage, and depletion of caspase-3 from cell extracts impaired caspase-8 cleavage after in vitro activation with dATP and cytochrome c. Thus, these data indicate that drug-induced caspase-8 activation in B-lymphoma cells is independent of death receptor signaling and is mediated by postmitochondrial caspase-3 activation.
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Affiliation(s)
- T Wieder
- Department of Hematology, Oncology and Tumor Immunology, University Medical Center Charité, Humboldt University of Berlin, Germany
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Lykidis A, Jackson P, Jackowski S. Lipid activation of CTP: phosphocholine cytidylyltransferase alpha: characterization and identification of a second activation domain. Biochemistry 2001; 40:494-503. [PMID: 11148044 DOI: 10.1021/bi002140r] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The CTP:phosphocholine cytidylyltransferase (CCT) governs the rate of phosphatidylcholine (PtdCho) biosynthesis, and its activity is governed by interaction with membrane lipids. The carboxy-terminus was dissected to delineate the minimum sequences required for lipid responsiveness. The helical domain is recognized as a site of lipid interaction, and all three tandem alpha-helical repeats from residues 257 through 290 were found to be required for regulation of enzymatic activity by this domain. Truncation of the carboxy-terminus to remove one or more of the alpha-helical repeats yielded catalytically compromised proteins that were not responsive to lipids but retained sufficient activity to accelerate PtdCho biosynthesis when overexpressed in vivo. The role of the helical region in lipid-activation was tested further by excising residues 257 through 309 to yield a protein that retained a 57-residue carboxy terminal domain fused to the catalytic core. This construct tested the hypothesis that the helical region inhibits activity in the absence of lipid rather than activates the enzyme in the presence of lipid. This hypothesis predicts constitutive activity for CCTalpha[Delta257-309]; however, this protein was tightly regulated by lipid with activities comparable to the full-length CCTalpha, in both the absence and presence of lipid. Activation of CCTalpha[Delta257-309] was dependent exclusively on anionic lipids, whereas full-length CCTalpha responded to either anionic or neutral lipids. Phosphatidic acid delivered in Triton X-100 micelles was the preferred activator of the second lipid-activation domain. These data demonstrate that CCTalpha can be regulated by lipids by two independent domains: (i) the three amphipathic alpha-helical repeats that interact with both neutral and anionic lipid mixtures and (ii) the last 57 residues that interact with anionic lipids. The results show that both domains are inhibitory in the absence of lipid and activating in the presence of lipid. Removal of both domains results in a nonresponsive, dysregulated enzyme with reduced activity. The data also demonstrate for the first time that the 57-residue carboxy-terminal domain in CCTalpha participates in lipid-mediated regulation and is sufficient for maximum activation of enzyme activity.
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Affiliation(s)
- A Lykidis
- Department of Biochemistry, St. Jude Children's Research Hospital, Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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Prokop A, Wieder T, Sturm I, Essmann F, Seeger K, Wuchter C, Ludwig WD, Henze G, Dörken B, Daniel PT. Relapse in childhood acute lymphoblastic leukemia is associated with a decrease of the Bax/Bcl-2 ratio and loss of spontaneous caspase-3 processing in vivo. Leukemia 2000; 14:1606-13. [PMID: 10995007 DOI: 10.1038/sj.leu.2401866] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Dysfunction of the p53/Bax/caspase-3 apoptosis signaling pathway has been shown to play a role in tumorigenesis and tumor progression, ie the development of acquired drug resistance. Low expression of the apoptosis inducer Bax correlates with poor response to therapy and shorter overall survival in solid tumors. In the present study, we analyzed the p53/Bax/caspase-3 pathway in a paired and an unpaired sample series of children with acute lymphoblastic leukemia (ALL) at initial diagnosis and relapse. The data demonstrate that both Bax expression levels and the Bax/Bcl-2 ratio are significantly lower in samples at relapse as compared with samples at initial diagnosis (P=0.013, Wilcoxon signed rank test (paired samples); P=0.0039, Mann-Whitney U test (unpaired samples)). The loss of Bax protein expression was not a consequence of Bax frameshift mutations of the G8 tract and could not be attributed to mutations of the p53 coding sequence (exons 5 to 8) which were detected to a similar extent in de novo ALL samples and at relapse. Analysis of the downstream effector caspase-3 showed loss of spontaneous caspase-3 processing at relapse. Whereas nine out of 14 (64%, paired samples) or 37 out of 77 (48%, unpaired samples) ALL patients at initial diagnosis displayed spontaneous in vivo processing of caspase-3, this was completely absent in patients at relapse (paired samples) or detected in only one out of 34 patients at relapse (2.9%, unpaired samples). We therefore conclude that in ALL relapse a severe disturbance of apoptotic pathways occurs, both at the level of Bax expression and caspase-3 activation.
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Affiliation(s)
- A Prokop
- Department of Pediatric Hematology/Oncology, University Medical Center Charité, Humboldt University of Berlin, Germany
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Clement JM, Kent C. CTP:phosphocholine cytidylyltransferase: insights into regulatory mechanisms and novel functions. Biochem Biophys Res Commun 1999; 257:643-50. [PMID: 10208837 DOI: 10.1006/bbrc.1999.0512] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A key regulatory enzyme in phosphatidylcholine biosynthesis, CTP:cholinephosphate cytidylyltransferase (CCT), catalyzes the formation of CDP-choline. This review discusses the essential features of CCT and addresses intriguing new insights into the catalytic and regulatory properties of this complex enzyme. Characterization of a lipid-binding segment in rat CCT is described and the role of lipids in CCT activation is discussed. An analysis of the phosphorylation domain is presented and possible physiological rationales for reversible phosphorylation of CCT are discussed. The nuclear localization of CCT is examined in the context of multiple CCT isoforms, as is recent evidence establishing a potential link between CCT activity and vesicular transport.
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Affiliation(s)
- J M Clement
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA
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16
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Batenburg JJ, Haagsman HP. The lipids of pulmonary surfactant: dynamics and interactions with proteins. Prog Lipid Res 1998; 37:235-76. [PMID: 10193527 DOI: 10.1016/s0163-7827(98)00011-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- J J Batenburg
- Laboratory of Veterinary Biochemistry, Graduate School of Animal Health, Utrecht University, The Netherlands.
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17
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Müller-Wieprecht V, Riebeling C, Alexander C, Scholz FR, Höer A, Wieder T, Orfanos CE, Geilen CC. Expression and regulation of phospholipase D in the human keratinocyte cell line HaCaT. FEBS Lett 1998; 425:199-203. [PMID: 9559647 DOI: 10.1016/s0014-5793(98)00227-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The generation of lipid second messengers via phosphatidylcholine (PC)-specific phospholipase D (PLD) has emerged as an important step leading to transduction of extracellular signals. In the present investigation the expression of human cytosolic PLD isoenzymes in the immortalized human keratinocyte cell line HaCat was determined. At the mRNA level we found the expression of hPLD1b and for the first time in human cells also the expression of hPLD2. For further analysis of enzyme expression at the protein level, hPLD1 peptide fragments were synthesized and specific antibodies were generated (rabbit) to be used for detection of hPLD1 in Western blot experiments. Furthermore, small G-proteins were found to be involved in the regulation of PLD activity in HaCaT cells using the guanine nucleotide analogue GTPgammaS.
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Affiliation(s)
- V Müller-Wieprecht
- Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, Germany
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18
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Abstract
CTP:phosphocholine cytidylyltransferase (CCT) catalyzes the synthesis of CDP-choline and is regulatory for phosphatidylcholine biosynthesis. This review focuses on recent developments in understanding the catalytic and regulatory mechanisms of this enzyme. Evidence for the nuclear localization of the enzyme is discussed, as well as evidence suggesting cytoplasmic localization. A comparison of the catalytic domains of CCTs from a wide variety of organisms is presented, highlighting a large number of completely conserved residues. Work implying a role for the conserved HXGH sequence in catalysis is described. The membrane-binding domain in rat CCT has been defined, and the role of lipids in activating the enzyme is discussed. The identification of the phosphorylation domain is described, as well as approaches to understand the role of phosphorylation in enzyme activity. Other possible control mechanisms such as enzyme degradation and gene expression are presented.
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Affiliation(s)
- C Kent
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor 48109-0606, USA.
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19
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Affiliation(s)
- P C Choy
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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20
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Wieder T, Geilen CC, Kolter T, Sadeghlar F, Sandhoff K, Brossmer R, Ihrig P, Perry D, Orfanos CE, Hannun YA. Bcl-2 antagonizes apoptotic cell death induced by two new ceramide analogues. FEBS Lett 1997; 411:260-4. [PMID: 9271217 DOI: 10.1016/s0014-5793(97)00717-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ceramides which arise in part from the breakdown of sphingomyelin comprise a class of antiproliferative lipids and have been implicated in the regulation of programmed cell death better known as apoptosis. In the present study, two new synthetic ceramide analogues, N-thioacetylsphingosine and FS-5, were used in Molt 4 cells to induce cell death. Besides their cytotoxic effects at concentrations > or = 14 microM the data obtained clearly show that both analogues induced apoptosis at concentrations below this critical concentration as assessed by trypan blue exclusion and cleavage of the death substrate poly-(ADP-ribose) polymerase (PARP). Additional experiments in bcl-2-transfected Molt 4 cells revealed that the apoptotic but not the lytic effects of the analogues were antagonized by the apoptosis inhibitor Bcl-2. Furthermore, neither N-thio-acetylsphingosine nor FS-5 induced PARP cleavage in bcl-2-transfected Molt 4 cells indicating that the induction of apoptotic cell death by cell permeable ceramides is not due to unspecific disturbance of the cell membrane.
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Affiliation(s)
- T Wieder
- Department of Dermatology, University Medical Center Benjamin Franklin, The Free University of Berlin, Germany
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21
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Yang J, Wang J, Tseu I, Kuliszewski M, Lee W, Post M. Identification of an 11-residue portion of CTP-phosphocholine cytidylyltransferase that is required for enzyme-membrane interactions. Biochem J 1997; 325 ( Pt 1):29-38. [PMID: 9224626 PMCID: PMC1218525 DOI: 10.1042/bj3250029] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
CTP-phosphocholine cytidylyltransferase (CT) is a key regulatory enzyme in the biosynthesis of phosphatidylcholine (PC) in many cells. Enzyme-membrane interactions appear to play an important role in CT activation. A putative membrane-binding domain appears to be located between residues 236 and 293 from the N-terminus. To map the membrane-binding domain more precisely, glutathione S-transferase fusion proteins were prepared that contained deletions of various domains in this putative lipid-binding region. The fusion proteins were assessed for their binding of [3H]PC/oleic acid vesicles. Fusion proteins encompassing residues 267-277 bound to PC/oleic acid vesicles, whereas fragments lacking this region exhibited no specific binding to the lipid vesicles. The membrane-binding characteristics of the CT fusion proteins were also examined using intact lung microsomes. Only fragments encompassing residues 267-277 competed with full-length 125I-labelled CT, expressed in recombinant Sf9 insect cells, for microsomal membrane binding. To investigate the role of this region in PC biosynthesis, A549 and L2 cells were transfected with cDNA for CT mutants under the control of a glucocorticoid-inducible long terminal repeat (LTR) promoter. Induction of CT mutants containing residues 267-277 in transfectants resulted in reduced PC synthesis. The decrease in PC synthesis was accompanied by a shift in endogenous CT activity from the particulate to the soluble fraction. Expression of CT mutants lacking this region in A549 and L2 cells did not affect PC formation and subcellular distribution of CT activity. These results suggest that the CT region located between residues 267 and 277 from the N-terminus is required for the interaction of CT with membranes.
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Affiliation(s)
- J Yang
- The Medical Research Council Group in Lung Development and the Neonatal Research Division, Hospital for Sick Children, Department of Pediatrics, University of Toronto, Toronto, Ontario M5G 1X8, Canada
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22
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Nakashima A, Hosaka K, Nikawa J. Cloning of a human cDNA for CTP-phosphoethanolamine cytidylyltransferase by complementation in vivo of a yeast mutant. J Biol Chem 1997; 272:9567-72. [PMID: 9083101 DOI: 10.1074/jbc.272.14.9567] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
CTP-phosphoethanolamine cytidylyltransferase (ET) is the enzyme that catalyzes the formation of CDP-ethanolamine in the phosphatidylethanolamine biosynthetic pathway from ethanolamine. We constructed a Saccharomyces cerevisiae mutant of which the ECT1 gene, putatively encoding ET, was disrupted. This mutant showed a growth defect on ethanolamine-containing medium and a decrease of ET activity. A cDNA clone was isolated from a human glioblastoma cDNA expression library by complementation of the yeast mutant. Introduction of this cDNA into the yeast mutant clearly restored the formation of CDP-ethanolamine and phosphatidylethanolamine in cells. ET activity in transformants was higher than that in wild-type cells. The deduced protein sequence exhibited homology with the yeast, rat, and human CTP-phosphocholine cytidylyltransferases, as well as yeast ET. The cDNA gene product was expressed as a fusion with glutathione S-transferase in Escherichia coli and shown to have ET activity. These results clearly indicate that the cDNA obtained here encodes human ET.
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Affiliation(s)
- A Nakashima
- Department of Biochemical Engineering and Science, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka 820, Japan
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23
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Johnson JE, Aebersold R, Cornell RB. An amphipathic alpha-helix is the principle membrane-embedded region of CTP:phosphocholine cytidylyltransferase. Identification of the 3-(trifluoromethyl)-3-(m-[125I]iodophenyl) diazirine photolabeled domain. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1324:273-84. [PMID: 9092714 DOI: 10.1016/s0005-2736(96)00233-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
CTP:phosphocholine cytidylyltransferase (CT), the rate controlling enzyme in phosphatidylcholine biosynthesis, is activated by reversible membrane binding. To investigate the membrane binding mechanism of CT, we have used the photoreactive hydrophobic probe 3-(trifluoromethyl)-3-(m-[l25I]iodophenyl)diazirine ([125I]TID). Association of CT with phosphatidylcholine/oleic acid (1:1) vesicles was first demonstrated by gel filtration analysis. Upon irradiation, CT was covalently labeled by [125I]TID presented in phosphatidylcholine/oleic acid vesicles. This demonstrates an intercalation of part of the protein into the hydrophobic core of the membrane. To identify the membrane-embedded domain, the chymotrypsin digestion products of [125I]TID labeled CT were analysed. Chymotrypsin digestion produced a set of previously defined N-terminal fragments (Craig, L., Johnson, J.E. and Cornell, R.B. (1994) J. Biol. Chem. 269, 3311), as well as several small C-terminal fragments which react with an anti-peptide antibody raised against the proposed amphipathic alpha-helix. All fragments containing the amphipathic helical region of the enzyme had [125I]TID label associated, while the chymotryptic fragment which lacked this region was not highly labeled. Similar fragment labeling patterns were produced when [125I]TID was presented in phosphatidylcholine/oleic acid or phosphatidylcholine/diacylglycerol vesicles, suggesting that the same domain of CT mediates binding to membranes containing either of the two lipid activators. A 62-residue synthetic peptide corresponding in sequence to the amphipathic helical region of CT was labeled with [125I]TID, demonstrating its ability to intercalate independently of the rest of the protein. These results indicate a membrane-binding mechanism for cytidylyltransferase involving the intercalation of the amphipathic alpha-helix region into the hydrophobic acyl chain core of the activating membrane.
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Affiliation(s)
- J E Johnson
- Department of Chemistry, Simon Fraser University, Burnaby, BC, Canada
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24
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Wieprecht M, Wieder T, Paul C, Geilen CC, Orfanos CE. Evidence for phosphorylation of CTP:phosphocholine cytidylyltransferase by multiple proline-directed protein kinases. J Biol Chem 1996; 271:9955-61. [PMID: 8626633 DOI: 10.1074/jbc.271.17.9955] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Reversible phosphorylation of CTP:phosphocholine cytidylyltransferase, the rate-limiting enzyme of phosphatidylcholine biosynthesis, is thought to play a role in regulating its activity. In the present study, the hypothesis that proline-directed kinases play a major role in phosphorylating cytidylyltransferase is substantiated using a c-Ha-ras-transfected clone of the human keratinocyte cell line HaCaT. Cellular extracts from epidermal growth factor-stimulated HaCaT cells and from ras-transfected HaCaT cells phosphorylated cytidylyltransferase much stronger as compared with extracts from quiescent HaCaT cells. The tryptic phosphopeptide pattern of cytidylyltransferase phosphorylated by cell-free extracts from ras-transfected HaCaT cells was similar compared with the patterns of cytidylyltransferase phosphorylated by p44mpkmitogen-activated protein kinase and p34cdc2 kinase in vitro, whereas in the case of casein kinase II the pattern was different. Furthermore, in c-Ha-ras-transfected HaCaT cells the in vivo phosphorylation state of cytidylyltransferase was 2-fold higher as compared with untransfected HaCaT cells. This higher phosphorylation of cytidylyltransferase in the ras-transfected clone was reduced to a level below the phosphorylation of cytidylyltransferase in untransfected cells, using olomoucine, a specific inhibitor of proline-directed kinases. The reduced phosphorylation of cytidylyltransferase in olomoucine-treated cells correlated with an enhanced stimulation of enzyme activity by oleic acid.
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Affiliation(s)
- M Wieprecht
- Institute of Molecular Biology and Biochemistry, University Medical Center Benjamin Franklin, Free University of Berlin, Berlin D-12200, Germany
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25
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Yang W, Boggs KP, Jackowski S. The association of lipid activators with the amphipathic helical domain of CTP:phosphocholine cytidylyltransferase accelerates catalysis by increasing the affinity of the enzyme for CTP. J Biol Chem 1995; 270:23951-7. [PMID: 7592590 DOI: 10.1074/jbc.270.41.23951] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The biochemical mechanism for the regulation of enzyme activity by lipid modulators and the role of the amphipathic alpha-helical domain of CTP:phosphocholine cytidylyltransferase (CT) was investigated by analyzing the kinetic properties of the wild-type protein and two truncation mutants isolated from a baculovirus expression system. The CT[delta 312-367] mutant protein lacked the carboxyl-terminal phosphorylation domain and retained high catalytic activity along with both positive and negative regulation by lipid modulators. The CT[delta 257-367] deletion removed in addition the region containing three consecutive amphipathic alpha-helical repeats. The CT[delta 257-367] mutant protein exhibited a significantly lower specific activity compared to CT or CT[delta 312-367] when expressed in either insect or mammalian cells; however, CT[delta 257-367] activity was refractory to either stimulation or inhibition by lipid regulators. Lipid activators accelerated CT activity by decreasing the Km for CTP from 24.7 mM in their absence to 0.7 mM in their presence. The Km for phosphocholine was not affected by lipid activators. The activity of CT[delta 257-367] was comparable to the activity of wild-type CT in the absence of lipid activators and the CTP Km for CT[delta 257-367] was 13.9 mM. The enzymatic properties of the CT[delta 231-367] mutant were comparable to those exhibited by the CT[257-367] mutant indicating that removal of residues 231 through 257 did not have any additional influence on the lipid regulation of the enzyme. Thus, the region between residues 257 and 312 was required to confer lipid regulation on CT, and the association of activating lipids with this region of the protein stimulated catalysis by increasing the affinity of the enzyme for CTP.
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Affiliation(s)
- W Yang
- Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA
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26
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Yeo HJ, Sri Widada J, Mercereau-Puijalon O, Vial HJ. Molecular cloning of CTP:phosphocholine cytidylyltransferase from Plasmodium falciparum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 233:62-72. [PMID: 7588775 DOI: 10.1111/j.1432-1033.1995.062_1.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
CTP:phosphocholine cytidylyltransferase (CCT) is the rate-limiting and regulatory enzyme in the synthesis of phosphatidylcholine, the major membrane phospholipid, in Plasmodium. The structural gene encoding CCT was isolated from the human malaria parasite Plasmodium falciparum. This was achieved using the PCR to amplify genomic DNA with degenerate primers constructed on the basis of conserved regions identified within yeast and rat liver CCT molecules, and using the PCR product to screen a genomic library. The P. falciparum CCT gene encodes a protein of 370 amino acids (42. 6 kDa) and displays 41-43% similarity (28-29% identity) to CCT molecules of the other organisms cloned to date. The central domain of CCT, proposed as the catalytic domain of the CTP-transfer reaction, shows 68-72% similarity and 48-55% identity among P. falciparum, human, rat and yeast enzymes. This gene is present in a single copy, as determined by Southern-blotting of genomic DNA, and located on chromosome 13 of P. falciparum. Large transcripts were detected by Northern analysis and indicate that this gene is expressed in the asexual intraerythrocytic stages. The coding region of the P. falciparum CCT gene was inserted into an Escherichia coli expression vector to confirm the function of the CCT product. The recombinant CCT expressed in E. coli is catalytically active, as evidenced by the conversion of phosphocholine to CDP-choline.
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Affiliation(s)
- H J Yeo
- CNRS URA 1856, Département Biologie-Santé, Université Montpellier II, France
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27
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Cornell RB, Kalmar GB, Kay RJ, Johnson MA, Sanghera JS, Pelech SL. Functions of the C-terminal domain of CTP: phosphocholine cytidylyltransferase. Effects of C-terminal deletions on enzyme activity, intracellular localization and phosphorylation potential. Biochem J 1995; 310 ( Pt 2):699-708. [PMID: 7654214 PMCID: PMC1135952 DOI: 10.1042/bj3100699] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The role of the C-terminal domain of CTP: phosphocholine cytidylyltransferase (CT) was explored by the creation of a series of deletion mutations in rat liver cDNA, which were expressed in COS cells as a major protein component. Deletion of up to 55 amino acids from the C-terminus had no effect on the activity of the enzyme, its stimulation by lipid vesicles or on its intracellular distribution between soluble and membrane-bound forms. However, deletion of the C-terminal 139 amino acids resulted in a 90% decrease in activity, loss of response to lipid vesicles and a significant decrease in the fraction of membrane-bound enzyme. Identification of the domain that is phosphorylated in vivo was determined by analysis of 32P-labelled CT mutants and by chymotrypsin proteolysis of purified CT that was 32P-labelled in vivo. Phosphorylation was restricted to the C-terminal 52 amino acids (domain P) and occurred on multiple sites. CT phosphorylation in vitro was catalysed by casein kinase II, cell division control 2 kinase (cdc2 kinase), protein kinases C alpha and beta II, and glycogen synthase kinase-3 (GSK-3), but not by mitogen-activated kinase (MAP kinase). Casein kinase II phosphorylation was directed exclusively to Ser-362. The sites phosphorylated by cdc2 kinase and GSK-3 were restricted to several serines within three proline-rich motifs of domain P. Sites phosphorylated in vitro by protein kinase C, on the other hand, were distributed over the N-terminal catalytic as well as the C-terminal regulatory domain. The stoichiometry of phosphorylation catalysed by any of these kinases was less than 0.2 mol P/mol CT, and no effects on enzyme activity were detected. This study supports a tripartite structure for CT with an N-terminal catalytic domain and a C-terminal regulatory domain comprised of a membrane-binding domain (domain M) and a phosphorylation domain (domain P). It also identifies three kinases as potential regulators in vivo of CT, casein kinase II, cyclin-dependent kinase and GSK-3.
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Affiliation(s)
- R B Cornell
- Institute of Molecular Biology, Simon Fraser University, Burnaby, British Columbia, Canada
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28
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Yang W, Jackowski S. Lipid activation of CTP:phosphocholine cytidylyltransferase is regulated by the phosphorylated carboxyl-terminal domain. J Biol Chem 1995; 270:16503-6. [PMID: 7622451 DOI: 10.1074/jbc.270.28.16503] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The role of the phosphorylated carboxyl-terminal domain of CTP:phosphocholine cytidylyltransferase (CT) in the regulation of enzyme activity was investigated by comparing the catalytic properties of wild-type CT to two mutant proteins with altered carboxyl-terminal phosphorylation domains. CT isolated from a baculovirus expression system was extensively phosphorylated at multiple sites in the carboxyl-terminal domain. The CT[S315A] mutant lacked a major CT phosphorylation site, and the carboxyl-terminal deletion mutant, CT[delta 312-367], was not phosphorylated. The higher activities of CT[delta 312-367] and CT[S315A] relative to CT were attributed to differences in the sensitivities of the enzymes to lipid activators. The rank order of the apparent Km values for activation by either phosphatidylcholine/oleic acid or phosphatidylcholine/diacylglycerol was CT > CT[S315A] > CT[delta 312-367]. In addition, CT exhibited negative cooperativity in its activation by phosphatidylcholine/oleic acid (nH = 0.64) and phosphatidylcholine/diacylglycerol (nH = 0.74) vesicles, whereas CT[delta 312-367] and CT[S315A] did not. These data support the concept that the phosphorylation of the CT carboxyl-terminal domain interferes with the activation of CT by lipid regulators.
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Affiliation(s)
- W Yang
- Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38101, USA
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29
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Wieprecht M, Wieder T, Geilen CC, Orfanos CE. Growth factors stimulate phosphorylation of CTP:phosphocholine cytidylyltransferase in HeLa cells. FEBS Lett 1994; 353:221-4. [PMID: 7926053 DOI: 10.1016/0014-5793(94)01040-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effect of insulin and epidermal growth factor on the phosphorylation of CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15) was investigated in HeLa cells. For the first time, cytidylyltransferase phosphorylation was shown to be influenced by growth factors in cell culture experiments. The rephosphorylation of cytidylyltransferase after an oleate-mediated dephosphorylation and translocation to membranes was increased after 2 min in the presence of insulin or epidermal growth factor by 99% and 76%, respectively, compared with controls. However, the increased phosphorylation of cytidylyltransferase did not have an effect on its subcellular distribution. Furthermore, purified cytidylyltransferase preincubated with alkaline phosphatase is a substrate for p44mapk, a member of the mitogen-activated protein (MAP) kinase family downstream of the growth factor receptors, in vitro. In accordance with the in vivo data, in vitro phosphorylation of cytidylyltransferase by p44mapk occurred after 2 min.
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Affiliation(s)
- M Wieprecht
- Institute of Molecular Biology and Biochemistry, University Medical Center Benjamin Franklin, Free University of Berlin, Germany
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