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Husbands AY, Feller A, Aggarwal V, Dresden CE, Holub AS, Ha T, Timmermans MCP. The START domain potentiates HD-ZIPIII transcriptional activity. THE PLANT CELL 2023; 35:2332-2348. [PMID: 36861320 DOI: 10.1093/plcell/koad058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/09/2023] [Accepted: 02/05/2023] [Indexed: 05/30/2023]
Abstract
The CLASS III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIPIII) transcription factors (TFs) were repeatedly deployed over 725 million years of evolution to regulate central developmental innovations. The START domain of this pivotal class of developmental regulators was recognized over 20 years ago, but its putative ligands and functional contributions remain unknown. Here, we demonstrate that the START domain promotes HD-ZIPIII TF homodimerization and increases transcriptional potency. Effects on transcriptional output can be ported onto heterologous TFs, consistent with principles of evolution via domain capture. We also show the START domain binds several species of phospholipids, and that mutations in conserved residues perturbing ligand binding and/or its downstream conformational readout abolish HD-ZIPIII DNA-binding competence. Our data present a model in which the START domain potentiates transcriptional activity and uses ligand-induced conformational change to render HD-ZIPIII dimers competent to bind DNA. These findings resolve a long-standing mystery in plant development and highlight the flexible and diverse regulatory potential coded within this widely distributed evolutionary module.
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Affiliation(s)
- Aman Y Husbands
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
- Department of Biology, University of Pennsylvania, 415 S. University Ave, Philadelphia, PA 19104, USA
| | - Antje Feller
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
| | - Vasudha Aggarwal
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Courtney E Dresden
- Department of Biology, University of Pennsylvania, 415 S. University Ave, Philadelphia, PA 19104, USA
- Molecular, Cellular, and Developmental Biology (MCDB), The Ohio State University, Columbus, OH 43215, USA
| | - Ashton S Holub
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43215, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Howard Hughes Medical Institute, Baltimore, MD 21205, USA
| | - Marja C P Timmermans
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
- Center for Plant Molecular Biology, University of Tübingen, Auf der Morgenstelle 32, 72076 Tübingen, Germany
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2
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Kleetz J, Vasilopoulos G, Czolkoss S, Aktas M, Narberhaus F. Recombinant and endogenous ways to produce methylated phospholipids in Escherichia coli. Appl Microbiol Biotechnol 2021; 105:8837-8851. [PMID: 34709431 PMCID: PMC8590670 DOI: 10.1007/s00253-021-11654-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 10/31/2022]
Abstract
Escherichia coli is the daily workhorse in molecular biology research labs and an important platform microorganism in white biotechnology. Its cytoplasmic membrane is primarily composed of the phospholipids phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin (CL). As in most other bacteria, the typical eukaryotic phosphatidylcholine (PC) is not a regular component of the E. coli membrane. PC is known to act as a substrate in various metabolic or catabolic reactions, to affect protein folding and membrane insertion, and to activate proteins that originate from eukaryotic environments. Options to manipulate the E. coli membrane to include non-native lipids such as PC might make it an even more powerful and versatile tool for biotechnology and protein biochemistry. This article outlines different strategies how E. coli can be engineered to produce PC and other methylated PE derivatives. Several of these approaches rely on the ectopic expression of genes from natural PC-producing organisms. These include PC synthases, lysolipid acyltransferases, and several phospholipid N-methyltransferases with diverse substrate and product preferences. In addition, we show that E. coli has the capacity to produce PC by its own enzyme repertoire provided that appropriate precursors are supplied. Screening of the E. coli Keio knockout collection revealed the lysophospholipid transporter LplT to be responsible for the uptake of lyso-PC, which is then further acylated to PC by the acyltransferase-acyl carrier protein synthetase Aas. Overall, our study shows that the membrane composition of the most routinely used model bacterium can readily be tailored on demand.Key points• Escherichia coli can be engineered to produce non-native methylated PE derivatives.• These lipids can be produced by foreign and endogenous proteins.• Modification of E. coli membrane offers potential for biotechnology and research.
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Affiliation(s)
- Julia Kleetz
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Georgios Vasilopoulos
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Simon Czolkoss
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Meriyem Aktas
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Franz Narberhaus
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany.
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3
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Wang Y, Wang C, Ren H, Jia B, Zhang L. Effectiveness of recombinant protein AlnA in enhancing the extractability of polychlorinated biphenyls from contaminated soils. JOURNAL OF HAZARDOUS MATERIALS 2014; 279:67-74. [PMID: 25038575 DOI: 10.1016/j.jhazmat.2014.06.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 06/27/2014] [Accepted: 06/28/2014] [Indexed: 06/03/2023]
Abstract
One of the major limitations in bioremediation of polychlorinated biphenyls (PCBs) in contaminated soils is their low water solubility and high adsorbability. In the present study, effectiveness of recombinant protein AlnA as a biosurfactant in increasing extractability of PCBs was first investigated. The AlnA surface tension measurements allowed for determination of the minimum value of 37.89mN/m with critical micelle concentration of 1.07g/L. The solubilization of PCBs and desorption experiments were performed. It was observed that AlnA at 20μg/mL could enhance solubility of selected crystal PCBs varying from 1.87 to 6.12 folds and it is easier to recover PCBs from contaminated soils compared with Tween-80 and cyclodextrin. Pot experiments indicated AlnA elevated 1.4-2.1-fold PCBs accumulation in roots by Alfalfa. The homology modeling and docking revealed PCBs congeners had different interactions with AlnA and higher-chlorinated PCBs possessed higher binding affinity. Results showed AlnA had considerable application potential in remediation of PCBs pollution.
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Affiliation(s)
- Yan Wang
- Key Laboratory of Groudwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, Changchun, Jilin 130021, China; College of Plant Sciences, Jilin University, Changchun, Jilin 130062, China
| | - Cong Wang
- Key Laboratory of Groudwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, Changchun, Jilin 130021, China
| | - Hejun Ren
- Key Laboratory of Groudwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, Changchun, Jilin 130021, China.
| | - Baolei Jia
- College of Plant Sciences, Jilin University, Changchun, Jilin 130062, China
| | - Lanying Zhang
- Key Laboratory of Groudwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, Changchun, Jilin 130021, China
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Kang HW, Wei J, Cohen DE. PC-TP/StARD2: Of membranes and metabolism. Trends Endocrinol Metab 2010; 21:449-56. [PMID: 20338778 PMCID: PMC2897958 DOI: 10.1016/j.tem.2010.02.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 02/03/2010] [Accepted: 02/04/2010] [Indexed: 11/25/2022]
Abstract
Phosphatidylcholine transfer protein (PC-TP, synonym StARD2) binds phosphatidylcholines, and catalyzes their intermembrane transfer and exchange in vitro. The structure of PC-TP comprises a hydrophobic pocket and a well-defined head group binding site, and its gene expression is regulated by peroxisome proliferator activated receptor-alpha. Recent studies have revealed key regulatory roles for PC-TP in lipid and glucose metabolism. Notably, Pctp(-/-) mice are sensitized to the action of insulin, and exhibit more efficient brown fat-mediated thermogenesis. PC-TP appears to limit access of fatty acids to mitochondria by stimulating the activity of thioesterase superfamily member 2, a newly characterized long-chain fatty acyl-coenzyme A thioesterase. Because PC-TP discriminates between phosphatidylcholines within lipid bilayers, it might function as a sensor that links metabolic regulation to membrane composition.
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Affiliation(s)
- Hye Won Kang
- Department of Medicine, Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Bose HS, Whittal RM, Bose M, Debnath D. Hydrophobic core of the steroidogenic acute regulatory protein for cholesterol transport. Biochemistry 2009; 48:1198-209. [PMID: 19170610 DOI: 10.1021/bi801514e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The steroidogenic acute regulatory protein (StAR), the first family member of START (StAR-related lipid transport) proteins, plays an essential role by facilitating the movement of cholesterol from the outer to inner mitochondrial membrane. Wild-type and mutant StAR binds cholesterol with similar intensity, but only wild-type StAR can transport it to mitochondria. Here, we report that the hydrophobic core is crucial for biological activity of proteins with START domains. Wild-type StAR increased steroidogenic activity by 7-9-fold compared to mutant R182L StAR, but both of them showed similar near-UV CD spectra. The fluorescence maximum of wild-type StAR is red shifted in comparison to mutant StAR under identical urea concentration. TFE increased the alpha-helical contribution of wild-type StAR more than the mutant protein. Acrylamide quenching for the wild-type protein (K(SV) = 12.0 +/- 0.2-11.2 +/- 0.5 M(-1)) exceeded that of the mutant protein (K(SV) = 4 +/- 0.2 M(-1)). Consistent with these findings, the hydrophobic probe ANS bound wild-type StAR (K(app) = 8.1 x 10(5) M(-1)) to a greater degree than mutant StAR (K(app) = 3.75 x 10(5) M(-1)). Partial proteolysis examined by mass spectrometry suggests that only wild-type StAR has a protease-sensitive C-terminus, but not the mutant. Stopped-flow CD revealed that the time of unfolding of mutant StAR was 0.017 s. In contrast, the wild-type StAR protein is unfolded in 16.3 s. In summary, these results demonstrate that wild-type StAR adopts a very flexible form due to the accommodation of more water molecules, while mutant StAR is generated by an alternate folding pathway making it inactive.
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Affiliation(s)
- Himangshu S Bose
- Department of Biomedical Sciences, Mercer University School of Medicine and Memorial Health University Medical Center, Savannah, Georgia 31404, USA.
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Tian J, Zhang S, Liu Z, Zhuang Y, Wang Y, Jiang S. Characterization and tissue-specific expression of phosphatidylcholine transfer protein gene from amphioxus Branchiostoma belcheri. Cell Tissue Res 2007; 330:53-61. [PMID: 17701056 DOI: 10.1007/s00441-007-0465-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Accepted: 07/04/2007] [Indexed: 11/30/2022]
Abstract
An amphioxus cDNA, encoding phosphatidylcholine transfer protein (AmphiPCTP), was identified for the first time from the gut cDNA library of Branchiostoma belcheri. It contains a 660-bp open reading frame corresponding to a deduced protein of 219 amino acids. Phylogenetic tree analysis showed that AmphiPCTP clustered with PCTP subgroup of PCTP subfamily containing steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domains. AmphiPCTP had an exon-intron organization similar to that of human and rat PCTP genes in terms of both exon number and sequence homology of each exon, suggesting that PCTP has probably maintained a similar function in both amphioxus and mammalian species. Both in situ hybridization histochemistry and whole-mount in situ hybridization revealed a tissue-specific expression pattern of AmphiPCTP with the high levels in the hepatic caecum and primitive gut, including the region where the hepatic caecum will form later during development. This apparently agrees with the hypothesis that amphioxus hepatic caecum is equivalent to vertebrate liver. These results suggest a conserved role of PCTPs in amphioxus as well as mammalian species.
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Affiliation(s)
- Jianxiao Tian
- Department of Marine Biology, Ocean University of China, Qingdao, China
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Perry RJ, Ridgway ND. Molecular mechanisms and regulation of ceramide transport. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1734:220-34. [PMID: 15907394 DOI: 10.1016/j.bbalip.2005.04.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 04/06/2005] [Accepted: 04/07/2005] [Indexed: 10/25/2022]
Abstract
De novo biosynthesis of sphingolipids begins in the endoplasmic reticulum (ER) and continues in the Golgi apparatus and plasma membrane. A crucial step in sphingolipid biosynthesis is the transport of ceramide by vesicular and non-vesicular mechanisms from its site of synthesis in the ER to the Golgi apparatus. The recent discovery of the ceramide transport protein CERT has revealed a novel pathway for the delivery of ceramide to the Golgi apparatus for sphingomyelin (SM) synthesis. In addition to a ceramide-binding START domain, CERT has FFAT (referring to two phenylalanines [FF] in an acidic tract) and pleckstrin homology (PH) domains that recognize the ER integral membrane protein VAMP-associated protein (VAP) and Golgi-associated PtdIns 4-phosphate, respectively. Mechanisms for vectorial transport involving dual-organellar targeting and sites of deposition of ceramide in the Golgi apparatus are proposed. Similar Golgi-ER targeting motifs are also present in the oxysterol-binding protein (OSBP), which regulates ceramide transport and SM synthesis in an oxysterol-dependent manner. Consequently, this emerges as a potential mechanism for integration of sphingolipid and cholesterol metabolism. The identification of organellar targeting motifs in other related lipid-binding/transport proteins indicate that concepts learned from the study of ceramide transport can be applied to other lipid transport processes.
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Affiliation(s)
- Ryan J Perry
- Atlantic Research Centre, Dalhousie University, 5849 University Avenue, Halifax, N.S., Canada B3H 4H7
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Olayioye MA, Vehring S, Müller P, Herrmann A, Schiller J, Thiele C, Lindeman GJ, Visvader JE, Pomorski T. StarD10, a START domain protein overexpressed in breast cancer, functions as a phospholipid transfer protein. J Biol Chem 2005; 280:27436-42. [PMID: 15911624 DOI: 10.1074/jbc.m413330200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We originally identified StarD10 as a protein overexpressed in breast cancer that cooperates with the ErbB family of receptor tyrosine kinases in cellular transformation. StarD10 contains a steroidogenic acute regulatory protein (StAR/StarD1)-related lipid transfer (START) domain that is thought to mediate binding of lipids. We now provide evidence that StarD10 interacts with phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by electron spin resonance measurement. Interaction with these phospholipids was verified in a fluorescence resonance energy transfer-based assay with 7-nitro-2,1,3-benzoxadiazol-4-yl-labeled lipids. Binding was not restricted to lipid analogs since StarD10 selectively extracted PC and PE from small unilamellar vesicles prepared with endogenous radiolabeled lipids from Vero monkey kidney cells. Mass spectrometry revealed that StarD10 preferentially selects lipid species containing a palmitoyl or stearoyl chain on the sn-1 and an unsaturated fatty acyl chain (18:1 or 18:2) on the sn-2 position. StarD10 was further shown to bind lipids in vivo by cross-linking of protein expressed in transfected HEK-293T cells with photoactivable phosphatidylcholine. In addition to a lipid binding function, StarD10 transferred PC and PE between membranes. Interestingly, these lipid binding and transfer specificities distinguish StarD10 from the related START domain proteins Pctp and CERT, suggesting a distinct biological function.
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Affiliation(s)
- Monilola A Olayioye
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Victoria 3050, Australia
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Schug KA, Lindner W. Noncovalent binding between guanidinium and anionic groups: focus on biological- and synthetic-based arginine/guanidinium interactions with phosph[on]ate and sulf[on]ate residues. Chem Rev 2005; 105:67-114. [PMID: 15720152 DOI: 10.1021/cr040603j] [Citation(s) in RCA: 459] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kevin A Schug
- University of Vienna, Department of Analytical Chemistry, Währingerstrasse 38, A-1090 Vienna, Austria.
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Kumagai K, Yasuda S, Okemoto K, Nishijima M, Kobayashi S, Hanada K. CERT mediates intermembrane transfer of various molecular species of ceramides. J Biol Chem 2004; 280:6488-95. [PMID: 15596449 DOI: 10.1074/jbc.m409290200] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ceramide produced at the endoplasmic reticulum is transported to the Golgi apparatus for conversion to sphingomyelin. The main pathway of endoplasmic reticulum-to-Golgi transport of ceramide is mediated by CERT, a cytosolic 68-kDa protein, in a nonvesicular manner. CERT contains a domain that catalyzes the intermembrane transfer of natural C(16)-ceramide. In this study, we examined the ligand specificity of CERT in detail by using a cell-free assay system for intermembrane transfer of lipids. CERT did not mediate the transfer of sphingosine or sphingomyelin at all. The activity of CERT to transfer saturated and unsaturated diacylglycerols, which structurally resemble ceramide, was 5-10% of the activity toward C(16)-ceramide. Among four stereoisomers of C(16)-ceramide, CERT specifically recognized the natural d-erythro isomer. CERT efficiently transferred ceramides having C(14), C(16), C(18), and C(20) chains, but not longer acyl chains, and also mediated efficient transfer of C(16)-dihydroceramide and C(16)-phyto-ceramide. Binding assays showed that CERT also recognizes short chain fluorescent analogs of ceramide with a stoichiometry of 1:1. Moreover, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecamide, which inhibited the CERT-dependent pathway of ceramide trafficking in intact cells, was found to be an antagonist of the CERT protein. These results indicate that CERT can mediate transfer of various types of ceramides that naturally exist and their close relatives.
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Affiliation(s)
- Keigo Kumagai
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640 and Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Allen-Baume V, Ségui B, Cockcroft S. Current thoughts on the phosphatidylinositol transfer protein family. FEBS Lett 2002; 531:74-80. [PMID: 12401207 DOI: 10.1016/s0014-5793(02)03412-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Monomeric transport of lipids is carried out by a class of proteins that can shield a lipid from the aqueous environment by binding the lipid in a hydrophobic cavity. One such group of proteins is the phosphatidylinositol transfer proteins (PITP) that can bind phosphatidylinositol and phosphatidylcholine and transfer them from one membrane compartment to another. PITPs are found in both unicellular and multicellular organisms but not bacteria. In mice and humans, the PITP domain responsible for lipid transfer is found in five proteins, which can be classified into two classes based on sequence. Class I PITPs comprises two family members, alpha and beta, small 35 kDa proteins with a single PITP domain which are ubiquitously expressed. Class IIA PITPs (RdgBalphaI and II) are larger proteins possessing additional domains that target the protein to membranes and are only able to bind lipids but not mediate transfer. Finally, Class IIB PITP (RdgBbeta) is similar to Class I in size (38 kDa) and is also ubiquitously expressed. Class III PITPs, exemplified by the Sec14p family, are found in yeast and plants but are unrelated in sequence and structure to Class I and Class II PITPs. In this review we discuss whether PITP proteins are passive transporters or are regulated proteins that are able to couple their transport and binding properties to specific biological functions including inositol lipid signalling and membrane turnover.
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Soccio RE, Adams RM, Romanowski MJ, Sehayek E, Burley SK, Breslow JL. The cholesterol-regulated StarD4 gene encodes a StAR-related lipid transfer protein with two closely related homologues, StarD5 and StarD6. Proc Natl Acad Sci U S A 2002; 99:6943-8. [PMID: 12011452 PMCID: PMC124508 DOI: 10.1073/pnas.052143799] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Using cDNA microarrays, we identified StarD4 as a gene whose expression decreased more than 2-fold in the livers of mice fed a high-cholesterol diet. StarD4 expression in cultured 3T3 cells was also sterol-regulated, and known sterol regulatory element binding protein (SREBP)-target genes showed coordinate regulation. The closest homologues to StarD4 were two other StAR-related lipid transfer (START) proteins named StarD5 and StarD6. StarD4, StarD5, and StarD6 are 205- to 233-aa proteins consisting almost entirely of START domains. These three constitute a subfamily among START proteins, sharing approximately 30% amino acid identity with one another, approximately 20% identity with the cholesterol-binding START domains of StAR and MLN64, and less than 15% identity with phosphatidylcholine transfer protein (PCTP) and other START domains. StarD4 and StarD5 were expressed in most tissues, with highest levels in liver and kidney, whereas StarD6 was expressed exclusively in the testis. In contrast to StarD4, expression of StarD5 and MLN64 was not sterol-regulated. StarD4, StarD5, and StarD6 may be involved in the intracellular transport of sterols or other lipids.
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Affiliation(s)
- Raymond E Soccio
- Laboratory of Biochemical Genetics and Metabolism, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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de Brouwer APM, Westerman J, Kleinnijenhuis A, Bevers LE, Roelofsen B, Wirtz KWA. Clofibrate-induced relocation of phosphatidylcholine transfer protein to mitochondria in endothelial cells. Exp Cell Res 2002; 274:100-11. [PMID: 11855861 DOI: 10.1006/excr.2001.5460] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The phosphatidylcholine transfer protein (PC-TP) is a specific transporter of phosphatidylcholine (PC) between membranes. To get more insight into its physiological function, we have studied the localization of PC-TP by microinjection of fluorescently labeled PC-TP in foetal bovine heart endothelial (FBHE) cells and by expression of an enhanced yellow fluorescent protein-PC-TP fusion protein in FBHE cells, human umbilical vein endothelial cells, and HepG2 cells. Analysis by confocal laser scanning microscopy showed that PC-TP was evenly distributed throughout the cytosol with an apparently elevated level in nuclei. By measuring the fluorescence recovery after bleaching it was established that PC-TP is highly mobile throughout the cell, with its transport into the nucleus being hindered by the nuclear envelope. Given the proposed function of PC-TP in lipid metabolism, we have tested a number of compounds (phorbol ester, bombesin, A23187, thrombin, dibutyryl cyclic AMP, oleate, clofibrate, platelet-derived growth factor, epidermal growth factor, and hydrogen peroxide) for their ability to affect intracellular PC-TP distribution. Only clofibrate (100 microM) was found to have an effect, with PC-TP moving to mitochondria within 5 min of stimulation. This relocation did not occur with PC-TP(S110A), lacking the putative protein kinase C (PKC)-dependent phosphorylation site, and was restricted to the primary endothelial cells. Relocation did not occur in HepG2 cells, possibly due to the fact that clofibrate does not induce PKC activation in these cells.
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Affiliation(s)
- A P M de Brouwer
- Department of Biochemistry of Lipids, Institute of Biomembranes, Padualaan 8, Utrecht, 3584 CH, The Netherlands.
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