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Madan B, Virshup DM, Nes WD, Leaver DJ. Unearthing the Janus-face cholesterogenesis pathways in cancer. Biochem Pharmacol 2021; 196:114611. [PMID: 34010597 DOI: 10.1016/j.bcp.2021.114611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 12/23/2022]
Abstract
Cholesterol biosynthesis, primarily associated with eukaryotes, occurs as an essential component of human metabolism with biosynthetic deregulation a factor in cancer viability. The segment that partitions between squalene and the C27-end cholesterol yields the main cholesterogenesis branch subdivided into the Bloch and Kandutsch-Russell pathways. Their importance in cell viability, in normal growth and development originates primarily from the amphipathic property and shape of the cholesterol molecule which makes it suitable as a membrane insert. Cholesterol can also convert to variant oxygenated product metabolites of distinct function producing a complex interplay between cholesterol synthesis and overall steroidogenesis. In this review, we disassociate the two sides of cholesterogenesisis affecting the type and amounts of systemic sterols-one which is beneficial to human welfare while the other dysfunctional leading to misery and disease that could result in premature death. Our focus here is first to examine the cholesterol biosynthetic genes, enzymes, and order of biosynthetic intermediates in human cholesterogenesis pathways, then compare the effect of proximal and distal inhibitors of cholesterol biosynthesis against normal and cancer cell growth and metabolism. Collectively, the inhibitor studies of druggable enzymes and specific biosynthetic steps, suggest a potential role of disrupted cholesterol biosynthesis, in coordination with imported cholesterol, as a factor in cancer development and as discussed some of these inhibitors have chemotherapeutic implications.
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Affiliation(s)
- Babita Madan
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore
| | - David M Virshup
- Program in Cancer and Stem Cell Biology, Duke-NUS Medical School, Singapore, Singapore; Department of Pediatrics, Duke University, Durham, NC, USA
| | - W David Nes
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, USA.
| | - David J Leaver
- Department of Biology, Geology, and Physical Sciences, Sul Ross State University, Alpine, TX, USA.
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2
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Girard J, Lanneau G, Delage L, Leroux C, Belcour A, Got J, Collén J, Boyen C, Siegel A, Dittami SM, Leblanc C, Markov GV. Semi-Quantitative Targeted Gas Chromatography-Mass Spectrometry Profiling Supports a Late Side-Chain Reductase Cycloartenol-to-Cholesterol Biosynthesis Pathway in Brown Algae. FRONTIERS IN PLANT SCIENCE 2021; 12:648426. [PMID: 33986764 PMCID: PMC8112355 DOI: 10.3389/fpls.2021.648426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 04/06/2021] [Indexed: 05/08/2023]
Abstract
Sterols are biologically important molecules that serve as membrane fluidity regulators and precursors of signaling molecules, either endogenous or involved in biotic interactions. There is currently no model of their biosynthesis pathways in brown algae. Here, we benefit from the availability of genome data and gas chromatography-mass spectrometry (GC-MS) sterol profiling using a database of internal standards to build such a model. We expand the set of identified sterols in 11 species of red, brown, and green macroalgae and integrate these new data with genomic data. Our analyses suggest that some metabolic reactions may be conserved despite the loss of canonical eukaryotic enzymes, like the sterol side-chain reductase (SSR). Our findings are consistent with the principle of metabolic pathway drift through enzymatic replacement and show that cholesterol synthesis from cycloartenol may be a widespread but variable pathway among chlorophyllian eukaryotes. Among the factors contributing to this variability, one could be the recruitment of cholesterol biosynthetic intermediates to make signaling molecules, such as the mozukulins. These compounds were found in some brown algae belonging to Ectocarpales, and we here provide a first mozukulin biosynthetic model. Our results demonstrate that integrative approaches can already be used to infer experimentally testable models, which will be useful to further investigate the biological roles of those newly identified algal pathways.
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Affiliation(s)
- Jean Girard
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Goulven Lanneau
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
- CNRS, Plateforme Corsaire-METABOMER (FR2424), Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Ludovic Delage
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Cédric Leroux
- CNRS, Plateforme Corsaire-METABOMER (FR2424), Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Arnaud Belcour
- Univ Rennes, Inria, CNRS, IRISA, Equipe Dyliss, Rennes, France
| | - Jeanne Got
- Univ Rennes, Inria, CNRS, IRISA, Equipe Dyliss, Rennes, France
| | - Jonas Collén
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Catherine Boyen
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Anne Siegel
- Univ Rennes, Inria, CNRS, IRISA, Equipe Dyliss, Rennes, France
| | - Simon M. Dittami
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Catherine Leblanc
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
| | - Gabriel V. Markov
- CNRS, Integrative Biology of Marine Models (LBI2M, UMR8227), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France
- *Correspondence: Gabriel V. Markov,
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3
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Weng X, Ma X, Wang Q, Xu K, Hu X, Liu W, Zhang C. Effect of hypothyroidism on CYP51 and FSHR expression in rat ovary. Theriogenology 2019; 138:145-151. [PMID: 31352176 DOI: 10.1016/j.theriogenology.2019.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 06/17/2019] [Accepted: 07/16/2019] [Indexed: 01/18/2023]
Abstract
Although thyroid hormone (TH) plays important roles in regulating ovarian development, the mechanism are still unclear. Cytochrome P450 lanosterol 14α-demethylase (CYP51) is a key enzyme in sterols and steroids biosynthesis that involved in folliculogenesis and oocyte maturation, which is regulated by follicle stimulating hormone (FSH). However, the effect of TH on CYP51 expression in ovarian cells is unclear. The objective of this study was to determine the effects of TH on CYP51 in rat ovary. Hypothyroidism rats were induced by 6-propyl-2-thiouracil (PTU), genes expressions in ovary were analyzed by Western blot or qRT-PCR. The data showed that CYP51 was significantly decreased in hypothyroidism, which was accompanied by the down-regulation of mRNA level. Meanwhile, similar tendency was also showed in FSHR expression in hypothyroidism. To evaluate the effect of the gonadotropin on CYP51 and FSHR expression in ovarian cells in vivo, hypo rats were injected subcutaneously with equine chorionic gonadotropin (eCG) respectively. The results showed that eCG reversed CYP51 and FSHR expression in hypo group. Moreover, FSH-induced CYP51 expression was meditated by FSHR. In addition, serum concentration of FSH and E2 were also decreased in hypothyroidism, and E2 was up-regulated by eCG treatment. These results indicate that hypothyroidism changes CYP51 and FSHR expression in ovary, which are regulated by gonadotropin. Moreover, genes changes in ovary are at least partially attributed to steroids biosynthesis.
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Affiliation(s)
- Xuechun Weng
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Xiaoshu Ma
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Qiaozhi Wang
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Kaili Xu
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Xusong Hu
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Wenbo Liu
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China
| | - Cheng Zhang
- College of Life Science, Capital Normal University, Beijing, 100048, People's Republic of China.
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4
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Hu X, Weng X, Tian Y, Wang C, Yang Y, Xu K, Zhang C. Effects of omega-3 polyunsaturated fatty acids on steroidogenesis and cellular development in PCOS rats. Food Funct 2019; 10:2504-2514. [DOI: 10.1039/c8fo02319k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine disorder, which is characterized by hyperandrogenism.
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Affiliation(s)
- Xusong Hu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health
- Beijing Technology and Business University (BTBU)
- Beijing 100048
- Peoples’ Republic of China
- College of Life Science
| | - Xuechun Weng
- College of Life Science
- Capital Normal University
- Beijing 100048
- Peoples’ Republic of China
| | - Ye Tian
- College of Life Science
- Capital Normal University
- Beijing 100048
- Peoples’ Republic of China
| | - Chengtao Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health
- Beijing Technology and Business University (BTBU)
- Beijing 100048
- Peoples’ Republic of China
| | - Yanzhou Yang
- Key Laboratory of Fertility Preservation and Maintenance
- Ministry of Education
- Key Laboratory of Reproduction and Genetics in Ningxia
- Department of Histology and Embryology
- Ningxia Medical University
| | - Kaili Xu
- College of Life Science
- Capital Normal University
- Beijing 100048
- Peoples’ Republic of China
| | - Cheng Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health
- Beijing Technology and Business University (BTBU)
- Beijing 100048
- Peoples’ Republic of China
- College of Life Science
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5
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Liu J, Tian Y, Ding Y, Heng D, Xu K, Liu W, Zhang C. Role of CYP51 in the Regulation of T3 and FSH-Induced Steroidogenesis in Female Mice. Endocrinology 2017; 158:3974-3987. [PMID: 28938463 DOI: 10.1210/en.2017-00249] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 08/15/2017] [Indexed: 01/31/2023]
Abstract
Cytochrome P450 lanosterol 14α-demethylase (CYP51) is a key enzyme in sterol and steroid biosynthesis that is involved in folliculogenesis and oocyte maturation, which is regulated by follicle-stimulating hormone (FSH), as a key reproductive hormone during follicular development. Thyroid hormone (TH) is also important for normal reproductive function. Although 3,5,3'-triiodothyronine (T3) enhances FSH-induced preantral follicle growth, whether and how TH combines with FSH to regulate CYP51 expression during the preantral to early antral transition stage is unclear. The objective of this study was to determine the cellular and molecular mechanisms by which T3 and FSH regulate CYP51 expression and steroid biosynthesis during preantral follicle growth. Our results indicated that CYP51 expression was upregulated in granulosa cells by FSH, and this response was enhanced by T3. Moreover, knockdown CYP51 decreased cell viability. Meanwhile, gene knockdown also blocked T3 and FSH-induced estradiol (E2) and progesterone (P4) synthesis. These changes were accompanied by upregulation of phospho-GATA-4 content. Results of small interfering RNA analysis showed that knockdown of GATA-4 significantly diminished CYP51 gene expression as well as E2/P4 levels. Furthermore, thyroid hormone receptor β was necessary to the activation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt), which was required for the regulation of CYP51 expression; activated GATA-4 was also involved these processes. Our data demonstrate that T3 and FSH cotreatment potentiates cellular development and steroid biosynthesis via CYP51 upregulation, which is mediated through the activation of the PI3K/Akt pathway. Meanwhile, activated GATA-4 is also involved in this regulatory system. These findings suggest that CYP51 is a mediator of T3 and FSH-induced follicular development.
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Affiliation(s)
- Juan Liu
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Ye Tian
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Yu Ding
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Dai Heng
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Kaili Xu
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Wenbo Liu
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
| | - Cheng Zhang
- College of Life Science, Capital Normal University, Beijing 100048, Peoples' Republic of China
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6
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Li X, Roberti R, Blobel G. Structure of an integral membrane sterol reductase from Methylomicrobium alcaliphilum. Nature 2015; 517:104-7. [PMID: 25307054 PMCID: PMC4285568 DOI: 10.1038/nature13797] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 08/26/2014] [Indexed: 01/04/2023]
Abstract
Sterols are essential biological molecules in the majority of life forms. Sterol reductases including Δ(14)-sterol reductase (C14SR, also known as TM7SF2), 7-dehydrocholesterol reductase (DHCR7) and 24-dehydrocholesterol reductase (DHCR24) reduce specific carbon-carbon double bonds of the sterol moiety using a reducing cofactor during sterol biosynthesis. Lamin B receptor (LBR), an integral inner nuclear membrane protein, also contains a functional C14SR domain. Here we report the crystal structure of a Δ(14)-sterol reductase (MaSR1) from the methanotrophic bacterium Methylomicrobium alcaliphilum 20Z (a homologue of human C14SR, LBR and DHCR7) with the cofactor NADPH. The enzyme contains ten transmembrane segments (TM1-10). Its catalytic domain comprises the carboxy-terminal half (containing TM6-10) and envelops two interconnected pockets, one of which faces the cytoplasm and houses NADPH, while the other one is accessible from the lipid bilayer. Comparison with a soluble steroid 5β-reductase structure suggests that the reducing end of NADPH meets the sterol substrate at the juncture of the two pockets. A sterol reductase activity assay proves that MaSR1 can reduce the double bond of a cholesterol biosynthetic intermediate, demonstrating functional conservation to human C14SR. Therefore, our structure as a prototype of integral membrane sterol reductases provides molecular insight into mutations in DHCR7 and LBR for inborn human diseases.
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Affiliation(s)
- Xiaochun Li
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
| | - Rita Roberti
- Department of Experimental Medicine, University of Perugia, 06132 Perugia, Italy
| | - Günter Blobel
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
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7
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8
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Modulation of hepatitis C virus genome encapsidation by nonstructural protein 4B. J Virol 2013; 87:7409-22. [PMID: 23616661 DOI: 10.1128/jvi.03523-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Hepatitis C Virus (HCV) NS4B protein has many roles in HCV genome replication. Recently, our laboratory (Q. Han, J. Aligo, D. Manna, K. Belton, S. V. Chintapalli, Y. Hong, R. L. Patterson, D. B. van Rossum, and K. V. Konan, J. Virol. 85:6464-6479, 2011) and others (D. M. Jones, A. H. Patel, P. Targett-Adams, and J. McLauchlan, J. Virol. 83:2163-2177, 2009; D. Paul, I. Romero-Brey, J. Gouttenoire, S. Stoitsova, J. Krijnse-Locker, D. Moradpour, and R. Bartenschlager, J. Virol. 85:6963-6976, 2011) have also reported NS4B's function in postreplication steps. Indeed, replacement of the NS4B C-terminal domain (CTD) in the HCV JFH1 (genotype 2a [G2a]) genome with sequences from Con1 (G1b) or H77 (G1a) had a negligible impact on JFH1 genome replication but attenuated virus production. Since NS4B interacts weakly with the HCV genome, we postulated that NS4B regulates the function of host or virus proteins directly involved in HCV production. In this study, we demonstrate that the integrity of the JFH1 NS4B CTD is crucial for efficient JFH1 genome encapsidation. Further, two adaptive mutations (NS4B N216S and NS5A C465S) were identified, and introduction of these mutations into the chimera rescued virus production to various levels, suggesting a genetic interaction between the NS4B and NS5A proteins. Interestingly, cells infected with chimeric viruses displayed a markedly decreased NS5A hyperphosphorylation state (NS5A p58) relative to JFH1, and the adaptive mutations differentially rescued NS5A p58 formation. However, immunofluorescence staining indicated that the decrease in NS5A p58 did not alter NS5A colocalization with the core around lipid droplets (LDs), the site of JFH1 assembly, suggesting that NS5A fails to facilitate the transfer of HCV RNA to the capsid protein on LDs. Alternatively, NS4B's function in HCV genome encapsidation may entail more than its regulation of the NS5A phosphorylation state.
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9
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Ačimovič J, Rozman D. Steroidal triterpenes of cholesterol synthesis. Molecules 2013; 18:4002-17. [PMID: 23558541 PMCID: PMC6269928 DOI: 10.3390/molecules18044002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/19/2013] [Accepted: 03/27/2013] [Indexed: 11/21/2022] Open
Abstract
Cholesterol synthesis is a ubiquitous and housekeeping metabolic pathway that leads to cholesterol, an essential structural component of mammalian cell membranes, required for proper membrane permeability and fluidity. The last part of the pathway involves steroidal triterpenes with cholestane ring structures. It starts by conversion of acyclic squalene into lanosterol, the first sterol intermediate of the pathway, followed by production of 20 structurally very similar steroidal triterpene molecules in over 11 complex enzyme reactions. Due to the structural similarities of sterol intermediates and the broad substrate specificity of the enzymes involved (especially sterol-Δ24-reductase; DHCR24) the exact sequence of the reactions between lanosterol and cholesterol remains undefined. This article reviews all hitherto known structures of post-squalene steroidal triterpenes of cholesterol synthesis, their biological roles and the enzymes responsible for their synthesis. Furthermore, it summarises kinetic parameters of enzymes (Vmax and Km) and sterol intermediate concentrations from various tissues. Due to the complexity of the post-squalene cholesterol synthesis pathway, future studies will require a comprehensive meta-analysis of the pathway to elucidate the exact reaction sequence in different tissues, physiological or disease conditions. A major reason for the standstill of detailed late cholesterol synthesis research was the lack of several steroidal triterpene standards. We aid to this efforts by summarizing commercial and laboratory standards, referring also to chemical syntheses of meiosis-activating sterols.
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Affiliation(s)
- Jure Ačimovič
- Centre for Functional Genomics and Bio-Chips, Faculty of Medicine, Institute of Biochemistry, University of Ljubljana, Zaloška 4, Ljubljana SI-1000, Slovenia.
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10
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Affiliation(s)
- W David Nes
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA.
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11
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Bennati AM, Schiavoni G, Franken S, Piobbico D, Della Fazia MA, Caruso D, De Fabiani E, Benedetti L, Cusella De Angelis MG, Gieselmann V, Servillo G, Beccari T, Roberti R. Disruption of the gene encoding 3beta-hydroxysterol Delta-reductase (Tm7sf2) in mice does not impair cholesterol biosynthesis. FEBS J 2008; 275:5034-47. [PMID: 18785926 DOI: 10.1111/j.1742-4658.2008.06637.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tm7sf2 gene encodes 3beta-hydroxysterol Delta(14)-reductase (C14SR, DHCR14), an endoplasmic reticulum enzyme acting on Delta(14)-unsaturated sterol intermediates during the conversion of lanosterol to cholesterol. The C-terminal domain of lamin B receptor, a protein of the inner nuclear membrane mainly involved in heterochromatin organization, also possesses sterol Delta(14)-reductase activity. The subcellular localization suggests a primary role of C14SR in cholesterol biosynthesis. To investigate the role of C14SR and lamin B receptor as 3beta-hydroxysterol Delta(14)-reductases, Tm7sf2 knockout mice were generated and their biochemical characterization was performed. No Tm7sf2 mRNA was detected in the liver of knockout mice. Neither C14SR protein nor 3beta-hydroxysterol Delta(14)-reductase activity were detectable in liver microsomes of Tm7sf2((-/-)) mice, confirming the effectiveness of gene inactivation. C14SR protein and its enzymatic activity were about half of control levels in the liver of heterozygous mice. Normal cholesterol levels in liver membranes and in plasma indicated that, despite the lack of C14SR, Tm7sf2((-/-)) mice are able to perform cholesterol biosynthesis. Lamin B receptor 3beta-hydroxysterol Delta(14)-reductase activity determined in liver nuclei showed comparable values in wild-type and knockout mice. These results suggest that lamin B receptor, although residing in nuclear membranes, may contribute to cholesterol biosynthesis in Tm7sf2((-/-)) mice. Affymetrix microarray analysis of gene expression revealed that several genes involved in cell-cycle progression are downregulated in the liver of Tm7sf2((-/-)) mice, whereas genes involved in xenobiotic metabolism are upregulated.
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Affiliation(s)
- Anna M Bennati
- Department of Internal Medicine, University of Perugia, Italy
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12
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Bennati AM, Castelli M, Della Fazia MA, Beccari T, Caruso D, Servillo G, Roberti R. Sterol dependent regulation of human TM7SF2 gene expression: role of the encoded 3beta-hydroxysterol Delta14-reductase in human cholesterol biosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA 2006; 1761:677-85. [PMID: 16784888 DOI: 10.1016/j.bbalip.2006.05.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 05/04/2006] [Accepted: 05/04/2006] [Indexed: 11/26/2022]
Abstract
3Beta-hydroxysterol Delta(14)-reductase operates during the conversion of lanosterol to cholesterol in mammalian cells. Besides the endoplasmic reticulum 3beta-hydroxysterol Delta(14)-reductase (C14SR) encoded by TM7SF2 gene, the lamin B receptor (LBR) of the inner nuclear membrane possesses 3beta-hydroxysterol Delta(14)-reductase activity, based on its ability to complement C14SR-defective yeast strains. LBR was indicated as the primary 3beta-hydroxysterol Delta(14)-reductase in human cholesterol biosynthesis, since mutations in LBR gene were found in Greenberg skeletal dysplasia, characterized by accumulation of Delta(14)-unsaturated sterols. This study addresses the issue of C14SR and LBR role in cholesterol biosynthesis. Both human C14SR and LBR expressed in COS-1 cells exhibit 3beta-hydroxysterol Delta(14)-reductase activity in vitro. TM7SF2 mRNA and C14SR protein expression in HepG2 cells grown in delipidated serum (LPDS) plus lovastatin (sterol starvation) were 4- and 8-fold higher, respectively, than in LPDS plus 25-hydroxycholesterol (sterol feeding), resulting in 4-fold higher 3beta-hydroxysterol Delta(14)-reductase activity. No variations in LBR mRNA and protein levels were detected in the same conditions. The induction of TM7SF2 gene expression is turned-on by promoter activation in response to low cell sterol levels and is mediated by SREBP-2. The results suggest a primary role of C14SR in human cholesterol biosynthesis, whereas LBR role in the pathway remains unclear.
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Affiliation(s)
- Anna Maria Bennati
- Department of Internal Medicine, Laboratory of Biochemistry, University of Perugia, Via del Giochetto, 06122 Perugia, Italy
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Lee EY, Shim YH, Chitwood DJ, Hwang SB, Lee J, Paik YK. Cholesterol-producing transgenic Caenorhabditis elegans lives longer due to newly acquired enhanced stress resistance. Biochem Biophys Res Commun 2005; 328:929-36. [PMID: 15707967 DOI: 10.1016/j.bbrc.2005.01.050] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Indexed: 10/25/2022]
Abstract
Because Caenorhabditis elegans lacks several components of the de novo sterol biosynthetic pathway, it requires sterol as an essential nutrient. Supplemented cholesterol undergoes extensive enzymatic modification in C. elegans to form other sterols of unknown function. 7-Dehydrocholesterol reductase (DHCR) catalyzes the reduction of the Delta7 double bond of sterols and is suspected to be defective in C. elegans, in which the major endogenous sterol is 7-dehydrocholesterol (7DHC). We microinjected a human DHCR expression vector into C. elegans, which was then incorporated into chromosome by gamma-radiation. This transgenic C. elegans was named cholegans, i.e., cholesterol-producing C. elegans, because it was able to convert 7DHC into cholesterol. We investigated the effects of changes in sterol composition on longevity and stress resistance by examining brood size, mean life span, UV resistance, and thermotolerance. Cholegans contained 80% more cholesterol than the wild-type control. The brood size of cholegans was reduced by 40% compared to the wild-type control, although the growth rate was not significantly changed. The mean life span of cholegans was increased up to 131% in sterol-deficient medium as compared to wild-type. The biochemical basis for life span extension of cholegans appears to partly result from its acquired resistance against both UV irradiation and thermal stress.
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Affiliation(s)
- Eun-Young Lee
- Department of Biochemistry, Bioproducts Research Center and Yonsei Proteome Research Center, Yonsei University, 134 Shinchon-dong, Sudaemoon-ku, Seoul 120-749, Republic of Korea
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14
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Yamashita Y, Nishibori M, Terada T, Isobe N, Shimada M. Gonadotropin-induced delta14-reductase and delta7-reductase gene expression in cumulus cells during meiotic resumption of porcine oocytes. Endocrinology 2005; 146:186-94. [PMID: 15459117 DOI: 10.1210/en.2004-0617] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Progesterone is produced from cholesterol in cumulus cells during meiotic resumption of porcine oocytes. In follicular cells, it has been shown that exogenous lipoprotein-bound cholesterol ester can be used for steroid hormone production. However, in serum-free medium, progesterone is also secreted by FSH- and LH-stimulated cumulus-oocyte complexes, suggesting that progesterone could be produced from de novo synthesized cholesterol in cumulus cells. In the present study, we investigated the expression of Delta14-reductase and Delta7-reductase, which are the members of the superfamily that converts acetyl-CoA to cholesterol in cumulus cells. The expression of both genes was analyzed by RT-PCR. Both Delta14-reductase mRNA and Delta7-reductase mRNA in cumulus cells, cultured until 4 h, were under the level of detection limit. In response to gonadotropins, both mRNA levels were dramatically up-regulated, reaching a maximum at 20 h. To clarify the role of induced enzymes in cumulus cells, cumulus-oocyte complexes were cultured with either Delta14-reductase inhibitor, AY9944-A-7, or Delta7-reductase inhibitor, BM15.766. The results indicated that these inhibitors significantly suppressed the progesterone production in cumulus cells and meiotic progression of oocytes. The inhibitory effects reached a maximum at 1 microM AY9944-A-7 or 20 microM BM15.766. The addition of 20 ng/ml progesterone overcame the inhibitory effects of both drugs on meiotic resumption of oocytes. These results imply that gonadotropin-induced expression and function of Delta14-reductase and Delta7-reductase in cumulus cells contribute to oocyte meiotic resumption via a progesterone-dependent pathway.
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Affiliation(s)
- Yasuhisa Yamashita
- Department of Applied Animal Science, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8528, Japan
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15
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Datta P, Bhattacharyya D. Spectroscopic and chromatographic evidences of NADPH in human placental extract used as wound healer. J Pharm Biomed Anal 2004; 34:1091-8. [PMID: 15019043 DOI: 10.1016/s0731-7085(03)00654-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2003] [Revised: 11/14/2003] [Accepted: 11/18/2003] [Indexed: 10/26/2022]
Abstract
An aqueous extract of human placenta, which is used as wound healer, has been investigated in terms of fluorescence properties. When excited at 340 nm, it results in fluorescence emission having maxima around 436 nm, which is fairly specific for nicotinamide adenine dinucleotide, reduced form (NADH) and nicotinamide adenine dinucleotide phosphate, reduced form (NADPH). The excitation spectra, having emission at 440 nm, show patterns comparable to these nucleotides. Thin layer chromatography and reversed-phase (RP) HPLC confirm presence of only NADPH in the extract. The emission and excitation patterns of NADPH purified after HPLC resemble exactly with the reference compound. Its content has been estimated to be 0.018 +/- 0.003 mg/ml based on fluorescence emission with respect to a standard calibration curve (n=6). Biological functionality of NADPH in the extract has been confirmed by glutathione reductase assay (n=5).
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Affiliation(s)
- Piyali Datta
- Division of Drug Design, Development & Molecular Modeling, Indian Institute of Chemical Biology, 4 Raja S.C. Mallick Road, Jadavpur, Calcutta 700032, India.
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16
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Gaylor JL. Membrane-bound enzymes of cholesterol synthesis from lanosterol. Biochem Biophys Res Commun 2002; 292:1139-46. [PMID: 11969204 DOI: 10.1006/bbrc.2001.2008] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Roberti R, Bennati AM, Galli G, Caruso D, Maras B, Aisa C, Beccari T, Della Fazia MA, Servillo G. Cloning and expression of sterol Delta 14-reductase from bovine liver. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:283-90. [PMID: 11784322 DOI: 10.1046/j.0014-2956.2001.02646.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Biosynthesis of cholesterol represents one of the fundamental cellular metabolic processes. Sterol Delta 14-reductase (Delta 14-SR) is a microsomal enzyme involved in the conversion of lanosterol to cholesterol in mammals. Amino-acid sequence analysis of a 38-kDa protein purified from bovine liver in our laboratory revealed > 90% similarity with a human sterol reductase, SR-1, encoded by the TM7SF2 gene, and with the C-terminal domain of human lamin B receptor. A cDNA encoding the 38-kDa protein, similar to human TM7SF2, was identified by analysis of a bovine expressed sequence tag (EST) database. The cDNA was synthesized by RT-PCR, cloned, and sequenced. The cDNA encodes a 418 amino-acid polypeptide with nine predicted transmembrane domains. The deduced amino-acid sequence exhibits high similarity with Delta 14-SR from yeasts, fungi, and plants (55-59%), suggesting that the bovine cDNA encodes Delta 14-SR. Northern blot analysis of bovine tissues showed high expression of mRNA in liver and brain. The polypeptide encoded by the cloned cDNA was expressed in COS-7 cells. Immunofluorescence analysis of transfected cells revealed a distribution of the protein throughout the ER. COS-7 cells expressing the protein exhibited Delta 14-SR activity about sevenfold higher than control cells. These results demonstrate that the cloned bovine cDNA encodes Delta 14-SR and provide evidence that the human TM7SF2 gene encodes Delta 14-SR.
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Affiliation(s)
- Rita Roberti
- Department of Internal Medicine, University of Perugia, Italy.
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18
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Rondet S, Taton M, Rahier A. Identification, characterization, and partial purification of 4 alpha-carboxysterol-C3-dehydrogenase/ C4-decarboxylase from Zea mays. Arch Biochem Biophys 1999; 366:249-60. [PMID: 10356290 DOI: 10.1006/abbi.1999.1218] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A microsomal preparation from seedlings of Zea mays catalyzed the NAD+-dependent oxidative decarboxylation of several substrates, including 4alpha-carboxy-cholest-7-en-3beta-ol, synthesized according to a new procedure, giving the first in vitro evidence for this enzymatic activity in a higher plant. A GC assay has been developed to detect the Delta7-cholestenone produced and the kinetic parameters of the microsomal system have been established. 4alpha-Carboxysterol decarboxylation shows an exclusive requirement for an oxidized pyridine nucleotide, with NAD+ being more efficient than NADP+. The decarboxylation reaction is independent of molecular oxygen. 4alpha-Carboxysterol-C3-dehydrogenase/C4-decarboxylase (4alpha-CD) is a microsome-bound protein which can be efficiently solubilized by detergents, including Brij W-1 and sodium cholate. The Brij W-1-solubilized enzyme was partially purified 290-fold by a combination of DEAE anion-exchange chromatography, Cibacron blue 3GA-agarose dye chromatography, and gel permeation. The apparent molecular mass of 4alpha-CD in sodium cholate was estimated to be 45 kDa. These results support the contention that demethylation at C4 of plant sterols is composed of two separate processes: an oxygen- and NAD(P)H-dependent oxidation of the 4alpha-methyl group to produce the 4alpha-carboxysterol metabolite (S. Pascal et al., J. Biol. Chem. 268, 11639, 1993) followed by oxygen-independent dehydrogenation/decarboxylation to produce an obligatory 3-ketosteroid.
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Affiliation(s)
- S Rondet
- Institut de Biologie Moléculaire des Plantes, CNRS UPR 406, 28 rue Goethe, Strasbourg Cedex, 67083, France
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19
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Bae SH, Lee JN, Fitzky BU, Seong J, Paik YK. Cholesterol biosynthesis from lanosterol. Molecular cloning, tissue distribution, expression, chromosomal localization, and regulation of rat 7-dehydrocholesterol reductase, a Smith-Lemli-Opitz syndrome-related protein. J Biol Chem 1999; 274:14624-31. [PMID: 10329655 DOI: 10.1074/jbc.274.21.14624] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cDNA encoding the 471-amino acid rat 7-dehydrocholesterol reductase (DHCR), an enzyme that has been implicated in both cholesterol biosynthesis and developmental abnormalities (e.g. Smith-Lemli-Opitz syndrome) in mammals, has been cloned and sequenced, and the primary structure of the enzyme has been deduced. The DHCR gene was mapped to chromosome 8q2.1 by fluorescence in situ hybridization. Rat DHCR, calculated molecular mass of 54.15-kDa polypeptide, shares a close amino acid identity with mouse and human DHCRs (96 and 87%, respectively) as compared with its other related proteins (e.g. fungal sterol Delta14-reductase) and exhibits high hydrophobicity (>68%) with 9 transmembrane domains. Five putative sterol-sensing domains were predicted to be localized in transmembrane domains 4-8, which are highly homologous to those found in 3-hydroxymethylglutaryl-CoA reductase, sterol regulatory element-binding protein cleavage-activating protein, and patched protein. The polypeptide encoded by DHCR cDNA was expressed in yeast as a 55.45-kDa myc-tagged fusion protein, which was recognized with anti-myc monoclonal antibody 9E10 and shown to possess full DHCR activity with respect to dependence on NADPH and sensitivity to DHCR inhibitors. Northern blot analysis indicates that the highest expression of DHCR mRNA was detected in liver, followed by kidney and brain. In rat brains, the highest level of mRNA encoding DHCR was detected in the midbrain, followed by the spinal cord and medulla. Feeding rats 5% cholestyramine plus 0.1% lovastatin in chow resulted in both approximately a 3-fold induction of DHCR mRNA and a 5-fold increase of the enzymic activity in the liver. When rats were fed 0.1% (w/w) AY-9944 (in chow) for 14-days, a complete inhibition of DHCR activity and a significant reduction in serum total cholesterol level were observed. However, the level of hepatic DHCR mRNA fell only slightly, suggesting that AY-9944 may act more rapidly at the protein level than at the level of transcription of the DHCR gene under these conditions.
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Affiliation(s)
- S H Bae
- Department of Biochemistry and Bioproducts Research Center, Yonsei University, Seoul, Korea
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20
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Solaja BA, Dermanović M, Lim DM, Paik YK, Tinant B, Declerq JP. The synthesis and in vitro activity of some delta 7,9(11)-lanostadienes. Steroids 1997; 62:709-18. [PMID: 9366010 DOI: 10.1016/s0039-128x(97)00075-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The synthesis of delta 7,9(11)-lanostadiene derivatives functionalized at C(32) starting from 3 beta-acetoxy-7 alpha,32-epoxylanostan-11-one has been presented. The delta 7,9(11) moiety was efficiently introduced in three steps in 71% yield by the regioselective abstraction of allylic 8 beta hydrogen. The formyl group of the key intermediate, 3 beta-benzoyloxylanosta-7,9(11)-dien-32-al, has been stereoselectively alkylated into (32S) derivative, whereas its oxidation unexpectedly afforded 3 beta-benzoyloxy-7-oxolanost-8-ene-32,11 alpha-lactone and not the corresponding acid. delta 7,9(11)-lanostadienes possessing HC(32)=O, C(32) [symbol: see text] N, HC(32S)CH3OH, H2C(32)OH, as well as some 11-keto lanostenes, were tested in vitro against several purified cholesterogenic enzymes showing moderate activity, with most the active aldehyde 16 having IC50 = 86 microM.
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Affiliation(s)
- B A Solaja
- Faculty of Chemistry, University of Belgrade, Yugoslavia.
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21
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Kim CK, Jeon KI, Lim DM, Johng TN, Trzaskos JM, Gaylor JL, Paik YK. Cholesterol biosynthesis from lanosterol: regulation and purification of rat hepatic sterol 14-reductase. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1259:39-48. [PMID: 7492613 DOI: 10.1016/0005-2760(95)00128-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have previously characterized the membrane-bound sterol 14-reductase (14-reductase) that catalyzes anaerobically NADPH-dependent reduction of the 14-double bond of delta 8,14-diene or delta 7,14-diene sterols that are sterol intermediates in cholesterol biosynthesis in mammals (Paik et al. (1984) J. Biol. Chem. 259, 13413-13423). To elucidate the regulatory mechanism as well as molecular characteristics of the 14-reductase, we extended our investigation on the consequences of alteration of the enzymic activity under various physiological conditions. The enzymic activity of rat hepatic sterol 14-reductase was induced more than 11-fold by feeding 5% cholestyramine plus 0.1% lovastatin (the CL-diet) for 7 days but was severely suppressed by feeding 5% cholesterol or 0.01% AY-9944 (an inhibitor of 14-reductase) for the same period. The increase or decrease in the 14-reductase activity also parallels the same change in the cholesterol synthetic rate in hepatocytes from rats that had been fed either the CL-diet or 0.01% AY-9944. In vitro inhibition studies revealed that AY-9944 acts as a competitive inhibitor of the 14-reductase (Ki = 0.26 microM). A diurnal variation was observed for the 14-reductase with peak activity near the middle of the dark cycle (10 p.m.), which was abolished by administration of cycloheximide. With induced enzyme conditions 14-reductase has been further purified with chromatographic procedures to near homogeneity. Purified 14-reductase appears to be a M(r) = 70,000 protein that is composed of two equally-sized subunits having a M(r) = 38,000. All properties of the purified 14-reductase suggest that the solubilized enzyme is the principal 14-reductase of microsomes. Taken together, our results provide the first evidence in support of a previously unknown regulatory role for the 14-reductase in the overall cholesterol synthetic pathway.
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Affiliation(s)
- C K Kim
- Department of Biochemistry, Yonsei University, Seoul, South Korea
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22
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Marcireau C, Guyonnet D, Karst F. Construction and growth properties of a yeast strain defective in sterol 14-reductase. Curr Genet 1992; 22:267-72. [PMID: 1394506 DOI: 10.1007/bf00317919] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We have transformed Saccharomyces cerevisiae with a genomic library contained in the replicative vector pFL44. The resulting transformants were screened for resistance to fenpropidin, a specific inhibitor of sterol 14-reductase. A plasmid was isolated that transformed yeast both to resistance to fenpropidin and to an increased specific activity of sterol 14-reductase. Sterol analysis of transformed cells grown in the presence of increasing concentrations of the inhibitor confirmed that resistance was a consequence of over-production of sterol 14-reductase. By chromosomal gene disruption, we have, for the first time, constructed yeast strains defective in sterol 14-reductase. As expected, since yeast in unable to take up sterols in aerobiosis, the disrupted strains do not grow in the presence of oxygen, even if exogenous sterols are supplied. However, disrupted cells grow in anaerobiosis with exogenous oleic acid and ergosterol supplements. They also grow in aerobiosis if they bear an additional mutation allowing sterol uptake. In this last growth condition the cells require a "sparking" ergosterol supplementation (25 nM) and accumulate ignosterol (ergosta-8,14-dienol) as the end-product of the sterol pathway. These results reveal that ignosterol is not obviously toxic to yeast membranes and strongly suggest that the molecular basis of the antifungal-activity morpholine and piperidine is directly related to the specific inhibition of ergosterol formation.
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Affiliation(s)
- C Marcireau
- Laboratoire de Biochimie et Génétique des Microorganismes, Université de Poitiers, France
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23
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Sono H, Sonoda Y, Sato Y. Purification and characterization of cytochrome P-45014DM (lanosterol 14 alpha-demethylase) from pig liver microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1078:388-94. [PMID: 1859829 DOI: 10.1016/0167-4838(91)90161-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cytochrome P-45014DM, which catalyzes lanosterol 14 alpha-demethylation, from pig liver microsomes was purified to a state of virtually homogeneous by gel electrophoresis. Its apparent monomeric molecular weight was estimated to be 53,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the amino-terminal amino acid sequence was Gly-Leu-Leu-Thr-Gly(Leu)-Asp-Leu-Leu-Gly-Ile. When reconstituted with NADPH-cytochrome P-450-reductase, the enzyme showed a high activity for lanosterol and 24,25-dihydrolanosterol 14 alpha-demethylation. Furthermore, the oxygenated intermediates of 24,25-dihydrolanosterol 14 alpha-demethylation, 32-hydroxy-24,25-dihydrolanosterol and 32-oxo-24,25-dihydrolanosterol, were converted to the 32-nor compound, 4,4-dimethylcholesta-8,14-dien-3 beta-ol, by the reconstituted enzyme system.
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Affiliation(s)
- H Sono
- Kyoritsu College of Pharmacy, Tokyo, Japan
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24
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Appelkvist EL, Reinhart M, Fischer R, Billheimer J, Dallner G. Presence of individual enzymes of cholesterol biosynthesis in rat liver peroxisomes. Arch Biochem Biophys 1990; 282:318-25. [PMID: 2241153 DOI: 10.1016/0003-9861(90)90123-g] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cholesterol biosynthesis by isolated rat liver peroxisomes was examined. Labeling of cholesterol from [3H]-mevalonate in the presence of peroxisomes required the addition of cytosol, since peroxisomes, like microsomes, apparently possess only those enzymes of cholesterol biosynthesis subsequent to the steps involving farnesyl-PP. Under the conditions employed the amounts of 4,4-dimethyl and desmethyl sterols generated by peroxisomes were equal to or exceeded those produced by the microsomes. In addition, marker enzyme analysis demonstrated minimal microsomal contamination in the peroxisomal fraction. The metabolite patterns observed by HPLC after incubation of these two fractions with [3H]mevalonate were different. Dihydrolanosterol oxidase, steroid-14-reductase, steroid-8-isomerase, and steroid-3-ketoreductase activities were present in peroxisomes. Separation of peroxisomes into membranes and contents revealed that all the synthesizing activities are associated with the membrane fraction. 7 alpha-Hydroxylase, which catalyzes the first step in the biosynthesis of bile acids, was also present in peroxisomes, but it remains to be clarified to what extent peroxisomal cholesterol is a substrate for bile acid synthesis.
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Affiliation(s)
- E L Appelkvist
- E.I. du Pont Nemours & Company, Central Research and Development Department, Wilmington, Delaware 19898
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25
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Taton M, Benveniste P, Rahier A. Microsomal delta 8,14-sterol delta 14-reductase in higher plants. Characterization and inhibition by analogues of a presumptive carbocationic intermediate of the reduction reaction. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 185:605-14. [PMID: 2591378 DOI: 10.1111/j.1432-1033.1989.tb15156.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An enzymatic assay for delta 8,14-sterol delta 14-reductase, an enzyme involved in sterol biosynthesis, has been developed for the first time in higher plants. The properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics and substrate specificity. This enzymatic double-bound reduction is thought to proceed through an electrophilic addition mechanism, involving a C14 putative carbonium ion high-energy intermediate. Using this in vitro assay, ammonium and iminium analogues of this cationic intermediate were shown to be potent inhibitors of the reduction reaction. Thus, compounds of the N-alkyl-8-aza-4 alpha,10-dimethyl-trans-decal-3 beta-ol series strongly inhibited sterol reductase (I50 = 0.07 - 4 microM) (I50/Km = 10(-4) - 10(-3), as did the antimycotic agent 15-azasterol (I50 = 0.03 microM); all of these compounds act as reaction-intermediate analogues of the proposed C14 carbonium ion intermediate. Moreover, the in vitro inhibition of the plant sterol reductase by a series of ammonium-ion-containing fungicides was demonstrated. The relative specificity of these different series of inhibitors toward cycloeucalenol-obtusifoliol isomerase, delta 8----delta 7-sterol isomerase and delta 8,14-sterol delta 14-reductase, was directly studied.
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Affiliation(s)
- M Taton
- Institut de Botanique, Unité Associée 1182 du Centre National de la Recherche Scientifique, Strasbourg, France
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26
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Mechanistic studies of lanosterol 14 alpha-methyl demethylase: substrate requirements for the component reactions catalyzed by a single cytochrome P-450 isozyme. J Lipid Res 1989. [DOI: 10.1016/s0022-2275(20)38245-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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27
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Powell WS, Gravelle F. Metabolism of 6-trans isomers of leukotriene B4 to dihydro products by human polymorphonuclear leukocytes. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69187-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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28
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29
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Reinhart MP, Billheimer JT, Faust JR, Gaylor JL. Subcellular localization of the enzymes of cholesterol biosynthesis and metabolism in rat liver. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47983-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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30
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Rahier A, Taton M. The 14 alpha-demethylation of obtusifoliol by a cytochrome P-450 monooxygenase from higher plants' microsomes. Biochem Biophys Res Commun 1986; 140:1064-72. [PMID: 3778482 DOI: 10.1016/0006-291x(86)90743-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Microsomes isolated from corn embryos (Zea mays) can demethylate the 14 alpha-methyl group of obtusifoliol 2. An enzymatic assay has been developed for obtusifoliol 14 alpha-methyl-demethylase in higher plants. The enzymatic reaction was shown to occur sequentially, converting obtusifoliol 2 to 4 alpha-methyl-5 alpha-ergosta-8,24(28)-dien-3 beta-ol 4 via the trienol 4 alpha-methyl-5 alpha-ergosta-8,14,24(28)-trien-3 beta-ol 3 which was thoroughly identified. This enzymatic reaction is dependent of NADPH and molecular oxygen. It is inhibited by CO, menadione and specific inhibitors of cytochrome P-450, the CO inhibition being partially reversed by light. It is concluded that in Zea mays microsomes, obtusifoliol is demethylated at C-14 by a cytochrome P-450 containing monooxygenase system.
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31
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Shafiee A, Trzaskos JM, Paik YK, Gaylor JL. Oxidative demethylation of lanosterol in cholesterol biosynthesis: accumulation of sterol intermediates. J Lipid Res 1986. [DOI: 10.1016/s0022-2275(20)38858-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Microsomal enzymes of cholesterol biosynthesis from lanosterol. Solubilization and purification of steroid 8-isomerase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)84586-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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33
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Chen JK, Okamoto T, Sato JD, Sato GH, McClure DB. Biochemical characterization of the cholesterol-dependent growth of the NS-1 mouse myeloma cell line. Exp Cell Res 1986; 163:117-26. [PMID: 3943557 DOI: 10.1016/0014-4827(86)90563-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The biochemical basis for the cholesterol-dependent growth phenotype of the NS-1 myeloma cell line has been investigated. In one series of experiments, the growth response of NS-1 cells to several of the intermediates of cholesterol biosynthesis was studied in serum-free medium. The cholesterol precursors, squalene and lanosterol, were totally ineffective in promoting NS-1 cell growth. In contrast, cholesterol precursors downstream from lanosterol, i.e., desmosterol and 7-dehydrocholesterol, completely replaced cholesterol in supporting NS-1 cell growth. In a second series of experiments, NS-1 cells and NS-1-503 cells (a cholesterol growth-independent variant of NS-1 cells) were labelled with [2-14C]acetate and the distributions of radioactivity between cholesterol and its precursors were determined by thin-layer chromatography using two different solvent systems. The major labelled sterol product (greater than 80%) in NS-1 cells after a 24-h exposure to [2-14C]acetate was lanosterol. In contrast, the major labelled sterol product (greater than 95%) in NS-1-503 cells after a 24-h exposure to [2-14C]acetate was cholesterol. Taken together, these results indicate that NS-1 cells are defective in cholesterol biosynthesis and identify the site of lesion as the demethylation of lanosterol to C-29 sterol intermediates.
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34
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Aoyama Y, Yoshida Y. Evidence for the contribution of a sterol 14-reductase to the 14 alpha-demethylation of lanosterol by yeast. Biochem Biophys Res Commun 1986; 134:659-63. [PMID: 2418830 DOI: 10.1016/s0006-291x(86)80470-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Lanosterol was converted to a 14-demethylated metabolite, 4,4-dimethylzymosterol by Saccharomyces cerevisiae microsomes. This metabolism was mediated by a cytochrome P-450 (P-450/14DM). However, a reconstituted system consisting of P-450/14DM and its reductase converted lanosterol to the 14-desaturated derivative of 4,4-dimethylzymosterol, 4,4-dimethyl-5 alpha-cholesta-8, 14,24-trien-3 beta-ol (trienol). When AY-9944 was added to the reaction system with the microsomes, the trienol was formed with corresponding decrease in 4,4-dimethylzymosterol. These observations indicate that the 14 alpha-demethylation of lanosterol by yeast microsomes occurs sequentially via the trienol. Reduction of the trienol to 4,4-dimethylzymosterol is mediated by an AY-9944-sensitive reductase.
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35
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Kawata S, Trzaskos JM, Gaylor JL. Microsomal enzymes of cholesterol biosynthesis from lanosterol. Purification and characterization of delta 7-sterol 5-desaturase of rat liver microsomes. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)88825-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Trzaskos JM, Bowen WD, Shafiee A, Fischer RT, Gaylor JL. Cytochrome P-450-dependent oxidation of lanosterol in cholesterol biosynthesis. Microsomal electron transport and C-32 demethylation. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90709-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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