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Lo Vasco VR, Leopizzi M, Puggioni C, Della Rocca C, Businaro R. Neuropeptide Y reduces the expression of PLCB2, PLCD1 and selected PLC genes in cultured human endothelial cells. Mol Cell Biochem 2014; 394:43-52. [PMID: 24903829 DOI: 10.1007/s11010-014-2079-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/03/2014] [Indexed: 12/11/2022]
Abstract
Endothelial cells (EC) are the first elements exposed to mediators circulating in the bloodstream, and react to stimulation with finely tuned responses mediated by different signal transduction pathways, leading the endothelium to adapt. Neuropeptide Y (NPY), the most abundant peptide in heart and brain, is mainly involved in the neuroendocrine regulation of the stress response. The regulatory roles of NPY depend on many factors, including its enzymatic processing, receptor subtypes and related signal transduction systems, including the phosphoinositide (PI) pathway and related phospholipase C (PI-PLC) family of enzymes. The panel of expression of PI-PLC enzymes differs comparing quiescent versus differently stimulated human EC. Growing evidences indicate that the regulation of the expression of PLC genes, which codify for PI-PLC enzymes, might act as an additional mechanism of control of the PI signal transduction pathway. NPY was described to potentiate the activation of PI-PLC enzymes in different cell types, including EC. In the present experiments, we stimulated human umbilical vein EC using different doses of NPY in order to investigate a possible role upon the expression PLC genes. NPY reduced the overall transcription of PLC genes, excepting for PLCE. The most significant effects were observed for PLCB2 and PLCD1, both isoforms recruited by means of G-proteins and G-protein-coupled receptors. NPY behavior was comparable with other PI-PLC interacting molecules that, beside the stimulation of phospholipase activity, also affect the upcoming enzymes' production acting upon gene expression. That might represent a mode to regulate the activity of PI-PLC enzymes after activation.
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Affiliation(s)
- V R Lo Vasco
- Department Organi di Senso, Policlinico Umberto I, Faculty of Medicina e Odontoiatria, Sapienza University of Rome, viale del Policlinico 155, 00185, Rome, Italy,
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Lo Vasco VR, Leopizzi M, Chiappetta C, Puggioni C, Di Cristofano C, Della Rocca C. Expression of phosphoinositide-specific phospholipase C enzymes in human skin fibroblasts. Connect Tissue Res 2013; 54:1-4. [PMID: 22800439 DOI: 10.3109/03008207.2012.712584] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Fibroblasts are involved in a number of functions regulated by different signal transduction pathways, including the phosphoinositide (PI) signaling system and related converting enzymes, such as phosphoinositide-specific phospholipase C (PI-PLC). The PI-PLC family comprises crucial effector enzymes in the PI signal transduction pathway. Once activated, PI-PLC cleaves an important membrane PI, the phosphatidylinositol (4,5) bisphosphate into inositol trisphosphate and diacylglycerol-both are crucial molecules in the transduction of signals. The activity of selected PI-PLC enzymes was reported in fibroblasts, although the complete panel of expression was not available. Each cell type expresses a group of selected PI-PLC isoforms, and knowledge of the panel of expression is a necessary and preliminary tool to address further studies. In the present study, we delineated the expression panel of PI-PLC enzymes in human skin fibroblasts. PI-PLC β1, PI-PLC β3, PI-PLC β4, PI-PLC γ1, PI-PLC γ2, PI-PLC δ1, PI-PLC δ3, PI-PLC δ4, and PI-PLC ϵ were expressed. PI-PLC β1 was weakly expressed, PI-PLC δ4 was inconstantly expressed, and PI-PLC γ2 was weakly expressed.
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Affiliation(s)
- V R Lo Vasco
- Department of Sensitive Organs, Policlinic Umberto I, Sapienza University of Rome, Rome, Italy.
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Pozzuolo S, Breme U, Salis B, Taylor G, Tonon G, Orsini G. Efficient bacterial expression of fusion proteins and their selective processing by a recombinant Kex-1 protease. Protein Expr Purif 2008; 59:334-41. [DOI: 10.1016/j.pep.2008.02.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Revised: 02/09/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
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Fang J, Marchesini N, Moreno S. A Toxoplasma gondii phosphoinositide phospholipase C (TgPI-PLC) with high affinity for phosphatidylinositol. Biochem J 2006; 394:417-25. [PMID: 16288600 PMCID: PMC1408672 DOI: 10.1042/bj20051393] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Toxoplasma gondii phosphoinositide-specific phospholipase C gene (TgPI-PLC) was cloned, sequenced and expressed in Escherichia coli and its enzymatic characteristics were investigated. TgPI-PLC is present in the genome as a single-copy gene consisting of 22 exons interrupted by 21 introns, and encodes a polypeptide of 1097 amino acids with a predicted molecular mass of 121 kDa. In addition to the conserved catalytic X and Y domains, TgPI-PLC contains an apparent N-terminal PH domain, an EF hand motif and a C-terminal C2 domain. When compared with mammalian delta-type PI-PLC, TgPI-PLC has an additional extended N-terminus and two insertions in the region between the X and Y domains, with a 31-35% identity over the whole sequence. Recombinant TgPI-PLC, as well as the native enzyme obtained from crude membrane extracts of the parasite, was more active with phosphatidylinositol than with phosphatidylinositol 4,5-bisphosphate as substrate. Indirect immunofluorescence analysis using an affinity-purified antibody against TgPI-PLC revealed that this enzyme localizes in the plasma membrane of the parasites.
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Affiliation(s)
- Jianmin Fang
- *Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, The University of Georgia, Athens, GA 30602, U.S.A
| | - Norma Marchesini
- †Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, University of Illinois at Urbana-Champaign, Urbana, IL 61802, U.S.A
| | - Silvia N. J. Moreno
- *Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, The University of Georgia, Athens, GA 30602, U.S.A
- †Laboratory of Molecular Parasitology, Department of Pathobiology and Center for Zoonoses Research, University of Illinois at Urbana-Champaign, Urbana, IL 61802, U.S.A
- To whom correspondence should be addressed (email )
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Phosphoinositide-specific phospholipase C (E.C. 3.1.4.11). Br J Pharmacol 2006. [DOI: 10.1038/sj.bjp.0706588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Kim MS, Seo JS, Choi GE, Lim SU, Chung JK, Lee HH. Molecular cloning and expression analysis of phospholipase Cδ from mud loach, Misgurnus mizolepis. Comp Biochem Physiol B Biochem Mol Biol 2004; 139:681-93. [PMID: 15581800 DOI: 10.1016/j.cbpc.2004.08.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2004] [Revised: 08/13/2004] [Accepted: 08/16/2004] [Indexed: 11/15/2022]
Abstract
A gene encoding phosphoinositide-specific phospholipase C (PLC), designated ML-PLCdelta, was cloned from mud loach (Misgurnus mizolepis) liver. A complete cDNA encoding ML-PLCdelta was isolated by screening the cDNA library of mud loach liver and using the 5'-rapid amplification of cDNA ends (RACE) method. The full-length ML-PLCdelta gene contains an open reading frame of 2325 base pairs encoding a 774 amino acid protein with a molecular mass of 88,072 Da; this corresponds to the size of the protein expressed in Escherichia coli BL21 (DE3) using pET28a vector. It contains all of the characteristic domains found in mammalian PLCdelta isozymes (PH domain, EF-hands, X-Y catalytic region, and a C2 domain). A homology search revealed that ML-PLCdelta shares relatively high sequence identity with mammalian PLCdelta1 (51-52%) and catfish PLCdelta (64%). The recombinant ML-PLCdelta protein expressed as a histidine-tagged fusion protein in E. coli was purified to apparent homogeneity by Ni(2+)-NTA affinity chromatography. The recombinant ML-PLCdelta showed a concentration-dependent PLC activity to phosphatidylinositol 4,5-bis-phosphate (PIP(2)) and its activity was Ca(2+)-dependent, which was similar to mammalian PLCdelta isozymes.
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Affiliation(s)
- Moo Sang Kim
- Department of Biotechnology, College of Fisheries Sciences, Pukyong National University, 599-1, Daeyean 3 Dong, Nam-gu, Busan, 608-737, South Korea
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Lee SB, Várnai P, Balla A, Jalink K, Rhee SG, Balla T. The Pleckstrin Homology Domain of Phosphoinositide-specific Phospholipase Cδ4 Is Not a Critical Determinant of the Membrane Localization of the Enzyme. J Biol Chem 2004; 279:24362-71. [PMID: 15037625 DOI: 10.1074/jbc.m312772200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The inositol lipid and phosphate binding properties and the cellular localization of phospholipase Cdelta(4) (PLCdelta(4)) and its isolated pleckstrin homology (PH) domain were analyzed in comparison with the similar features of the PLCdelta(1) protein. The isolated PH domains of both proteins showed plasma membrane localization when expressed in the form of a green fluorescent protein fusion construct in various cells, although a significantly lower proportion of the PLCdelta(4) PH domain was membrane-bound than in the case of PLCdelta(1)PH-GFP. Both PH domains selectively recognized phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)), but a lower binding of PLCdelta(4)PH to lipid vesicles containing PI(4,5)P(2) was observed. Also, higher concentrations of inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)) were required to displace the PLCdelta(4)PH from the lipid vesicles, and a lower Ins(1,4,5)P(3) affinity of PLCdelta(4)PH was found in direct Ins(1,4,5)P(3) binding assays. In sharp contrast to the localization of its PH domain, the full-length PLCdelta(4) protein localized primarily to intracellular membranes mostly to the endoplasmic reticulum (ER). This ER localization was in striking contrast to the well documented PH domain-dependent plasma membrane localization of PLCdelta(1). A truncated PLCdelta(4) protein lacking the entire PH domain still showed the same ER localization as the full-length protein, indicating that the PH domain is not a critical determinant of the localization of this protein. Most important, the full-length PLCdelta(4) enzyme still showed binding to PI(4,5)P(2)-containing micelles, but Ins(1,4,5)P(3) was significantly less potent in displacing the enzyme from the lipid than with the PLCdelta(1) protein. These data suggest that although structurally related, PLCdelta(1) and PLCdelta(4) are probably differentially regulated in distinct cellular compartments by PI(4,5)P(2) and that the PH domain of PLCdelta(4) does not act as a localization signal.
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Affiliation(s)
- Sang Bong Lee
- Laboratory of Cell Signaling, NHLI, National Institutes of Health, Bethesda, Maryland 20892, USA
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Yagisawa H, Yamaga M, Okada M, Sasaki K, Fujii M. Regulation of the intracellular localization of phosphoinositide-specific phospholipase Cdelta(1). ADVANCES IN ENZYME REGULATION 2002; 42:261-84. [PMID: 12123720 DOI: 10.1016/s0065-2571(01)00040-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Hitoshi Yagisawa
- Department of Life Science, Himeji Institute of Technology, Harima Science Garden City, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
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Okada M, Fujii M, Yamaga M, Sugimoto H, Sadano H, Osumi T, Kamata H, Hirata H, Yagisawa H. Carboxyl-terminal basic amino acids in the X domain are essential for the nuclear import of phospholipase C δ1. Genes Cells 2002; 7:985-96. [PMID: 12296828 DOI: 10.1046/j.1365-2443.2002.00577.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Although phospholipase C (PLC)delta1 containing a functional nuclear export signal (NES) is normally localized at the plasma membrane and in the cytoplasm, it shuttles between the nucleus and the cytoplasm. Since nucleocytoplasmic shuttling of a molecule is generally regulated by a balance between its NES and the nuclear localization signal (NLS), we examined whether PLCdelta1 contains an NLS sequence. RESULTS A region corresponding to the C terminus of the X domain and the XY-linker, which contains clusters of basic amino acid residues, was essential for the nuclear import of PLCdelta1 in Madin-Darby canine kidney cells. A series of point mutations on lysine residues in this region revealed that K432 and K434 in combination were important for the nuclear import. A short synthetic peptide corresponding to residues 429-442, however, was not able to function as an NLS sequence when they were injected into the cytoplasm in a carrier-conjugated form. Neither a longer peptide equivalent to PLCdelta1 412-498 fused to a protein tag consisting of glutathione S-transferase and green fluorescent protein was imported to the nucleus after microinjection into the cytoplasm. CONCLUSION The nuclear import of PLCdelta1 requires the C-terminus of the X domain, particularly the amino acid residues K432 and K434, and the XY-linker. The region alone, however, cannot serve as a functional NLS. The machinery for nuclear transport may require additional structural component(s) of the enzyme.
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Affiliation(s)
- Masashi Okada
- Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Hyogo 678-1297, Japan
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Lowenstein CJ. Purification and assessment of proteins associated with nitric oxide synthase. Methods Enzymol 2002; 353:233-40. [PMID: 12078498 DOI: 10.1016/s0076-6879(02)53051-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Charles J Lowenstein
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Lin FG, Cheng HF, Lee IF, Kao HJ, Loh SH, Lee WH. Downregulation of phospholipase C delta3 by cAMP and calcium. Biochem Biophys Res Commun 2001; 286:274-80. [PMID: 11500033 DOI: 10.1006/bbrc.2001.5371] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Four different isoforms of mammalian phospholipase C delta (PLCdelta) have been described. PLCdelta1, the best-understood isoform, is activated by an atypical GTP-binding protein. It has been suggested that it is a calcium signal amplifier. However, very less is known about other subtypes, including PLCdelta3. Therefore, in the present study, we examined the expression of PLCdelta3 in different human tissues. Moreover, the cellular underlying regulation for PLCdelta3 was studied in different cell lines. Our study showed that the mRNA and protein levels differed significantly among human tissues. The human PLCdelta3 gene was composed of 15 exons and 1 putative cAMP response element in the 5'-end promoter region. PLCdelta3 mRNA expression was downregulated by cAMP and calcium in both the human normal embryonic lung tissue diploid WI38 cell line and the glioblastoma/astrocytoma U373 cell line. However, mRNA expression showed no impact by PKC activators or inhibitors. This study shows the human PLCdelta3 expression pattern and is the first report that PLCdelta3 gene expression is downregulation by cAMP and calcium.
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Affiliation(s)
- F G Lin
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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Rebecchi MJ, Pentyala SN. Structure, function, and control of phosphoinositide-specific phospholipase C. Physiol Rev 2000; 80:1291-335. [PMID: 11015615 DOI: 10.1152/physrev.2000.80.4.1291] [Citation(s) in RCA: 725] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phosphoinositide-specific phospholipase C (PLC) subtypes beta, gamma, and delta comprise a related group of multidomain phosphodiesterases that cleave the polar head groups from inositol lipids. Activated by all classes of cell surface receptor, these enzymes generate the ubiquitous second messengers inositol 1,4, 5-trisphosphate and diacylglycerol. The last 5 years have seen remarkable advances in our understanding of the molecular and biological facets of PLCs. New insights into their multidomain arrangement and catalytic mechanism have been gained from crystallographic studies of PLC-delta(1), while new modes of controlling PLC activity have been uncovered in cellular studies. Most notable is the realization that PLC-beta, -gamma, and -delta isoforms act in concert, each contributing to a specific aspect of the cellular response. Clues to their true biological roles were also obtained. Long assumed to function broadly in calcium-regulated processes, genetic studies in yeast, slime molds, plants, flies, and mammals point to specific and conditional roles for each PLC isoform in cell signaling and development. In this review we consider each subtype of PLC in organisms ranging from yeast to mammals and discuss their molecular regulation and biological function.
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Affiliation(s)
- M J Rebecchi
- Departments of Anesthesiology and Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, New York 11794, USA.
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Yamaga M, Fujii M, Kamata H, Hirata H, Yagisawa H. Phospholipase C-delta1 contains a functional nuclear export signal sequence. J Biol Chem 1999; 274:28537-41. [PMID: 10497218 DOI: 10.1074/jbc.274.40.28537] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously observed, using a green fluorescent protein (GFP) fusion system, that PLC-delta1 is localized mainly at the plasma membrane and in the cytosol, whereas little is present in the nucleus in Madin-Darby canine kidney cells (Fujii, M., Ohtsubo, M., Ogawa, T., Kamata, H., Hirata, H., and Yagisawa, H. (1999) Biochem. Biophys. Res. Commun. 254, 284-291). Herein, we demonstrate that PLC-delta1 has a functional nuclear export signal (NES) sequence in amino acid residues 164-177 of the EF-hand domain. The fluorescence of NES-disrupted GFP/PLC-delta1 expressed in Madin-Darby canine kidney cells was present not only at the plasma membrane and in the cytosol but also in the nucleus. Moreover, treatment with leptomycin B, a specific inhibitor of NES-dependent nuclear export, resulted in the accumulation of GFP/PLC-delta1 in the nucleus. A site-directed mutant containing a pleckstrin homology domain, which does not bind inositol 1,4,5-trisphosphate and cannot hydrolyze phosphatidylinositol 4,5-bisphosphate in vitro, accumulated in the nucleus to a much greater extent than wild-type GFP/PLC-delta1 after treatment with leptomycin B. These results suggest that PLC-delta1 is shuttled between the cytoplasm and the nucleus; its nuclear export is dependent on the leucine-rich NES sequence and its active nuclear import is regulated by an unidentified signal(s).
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Affiliation(s)
- M Yamaga
- Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Hyogo 678-1297, Japan
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Pawelczyk T, Matecki A. Phospholipase C-delta3 binds with high specificity to phosphatidylinositol 4,5-bisphosphate and phosphatidic acid in bilayer membranes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 262:291-8. [PMID: 10336610 DOI: 10.1046/j.1432-1327.1999.00388.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In order to acquire an understanding of phospholipase C-delta3 (PLC-delta3) action on substrate localized in lipid membrane we have studied the binding of human recombinant PLC-delta3 to large, unilamellar phospholipid vesicles (LUVs). PLC-delta3 bound weakly to vesicles composed of phosphatidylcholine (PtdCho) or PtdCho plus phosphatidylethanolamine (PtdEtn) or phosphatidylinositol (PtdIns). The enzyme bound strongly to LUVs composed of PtdEtn + PtdCho and phosphatidylinositol 4,5-bisphosphate (PtdInsP2). The binding affinity (molar partition coefficient) of PLC-delta3 to PtdEtn + PtdCho + PtdInsP2 vesicles was 7.7 x 105 m-1. High binding of PLC-delta3 was also observed for LUVs composed of phosphatidic acid (PA). Binding of PLC-delta3 to phosphatidylserine (PtdSer) vesicles was less efficient. Calculated molar partition coefficient for binding of PLC-delta3 to PA and PtdSer vesicles was 1.6 x 104 m-1 and 9.4 x 102 m-1, respectively. Presence of PA in the LUVs containing PtdInsP2 considerably enhanced the binding of PLC-delta3 to the phospholipid membrane. Binding of PLC-delta3 to phospholipid vesicles was not dependent on Ca2+ presence. In the liposome assay PA caused a concentration-dependent increase in activity of PLC-delta3. The stimulatory effect of PA on PLC-delta3 was calcium-dependent. At Ca2+ concentrations lower than 1 microm, no effect of PA on the activity of PLC-delta3 was observed. PA enhanced PLC-delta3 activity by increasing the Vmax and lowering Km for PtdInsP2. As the mol fraction of PA increased from 0-40 mol% the enzyme Vmax increased 2.3-fold and Km decreased threefold. Based on the results presented, we assume that PA supports binding of PLC-delta3 to lipid membranes by interaction with the PH domain of the enzyme. The stimulatory effect of PA depends on calcium-dependent interaction with the C2 domain of PLC-delta3. We propose that binding of PLC-delta3 to PA may serve as a mechanism for dynamic membrane association and modulation of PLC-delta3 activity.
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Affiliation(s)
- T Pawelczyk
- Department of Molecular Medicine, Medical University of Gdansk, Poland.
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Richard EA, Ghosh S, Lowenstein JM, Lisman JE. Ca2+/calmodulin-binding peptides block phototransduction in Limulus ventral photoreceptors: evidence for direct inhibition of phospholipase C. Proc Natl Acad Sci U S A 1997; 94:14095-9. [PMID: 9391158 PMCID: PMC28438 DOI: 10.1073/pnas.94.25.14095] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Phototransduction in Limulus photoreceptors involves a G protein-mediated activation of phospholipase C (PLC) and subsequent steps involving InsP3-mediated release of intracellular Ca2+. While exploring the role of calmodulin in this cascade, we found that intracellular injection of Ca2+/calmodulin-binding peptides (CCBPs) strongly inhibited the light response. By chemically exciting the cascade at various stages, we found the primary target of this effect was not in late stages of the cascade but rather at the level of G protein and PLC. That PLCdelta1 contains a calmodulin-like structure raised the possibility that PLC might be directly affected by CCBPs. To test this possibility, in vitro experiments were conducted on purified PLC. The activity of this enzyme was strongly inhibited by CCBPs and also inhibited by calmodulin itself. Our results suggest that the calmodulin-like region of PLC has an important role in regulating this enzyme.
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Affiliation(s)
- E A Richard
- Biology, Brandeis University, Waltham, MA 02254-9110, USA
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Pawelczyk T, Lowenstein JM. The effect of different molecular species of sphingomyelin on phospholipase C delta 1 activity. Biochimie 1997; 79:741-8. [PMID: 9523016 DOI: 10.1016/s0300-9084(97)86932-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bovine brain sphingomyelin was separated into different molecular species using a reverse phase column. PLC delta 1 was inhibited by all molecular species of sphingomyelin. The extent of this inhibition was dependent on the hydrophobicity. Based on fatty acid analysis, we conclude that the inhibition of PLC delta 1 depends on the chain length and degree of unsaturation of the fatty acid moiety of SM. N-palmitoyl-D-sphingomyelin and N-stearoyl-D-sphingomyelin inhibited PLC delta 1 less then N-oleoyl-D-sphingomyelin. In the absence of Ca2+ (1 mM EGTA) all tested molecular species of SM inhibited weakly the enzyme. The sensitivity of PLC delta 1 to inhibition by SM increased with increasing Ca2+ concentration. The shape of calcium curve differed for molecular species with saturated and unsaturated fatty acids. Inhibition of PLC delta 1 by N-palmitoyl-D-sphingomyelin and N-stearoyl-D-sphingomyelin reached a maximum at 0.2 microM Ca2+, while inhibition by N-oleoyl-D-sphingomyelin reached maximum at 2 microM Ca2+. PLC delta 1 is more sensitive to inhibition by SM when it is maximally activated by spermine and calcium and the extent of this inhibition depends on the length and degree of fatty acid unsaturation of the molecular species.
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Affiliation(s)
- T Pawelczyk
- Department of Clinical Biochemistry, Medical University of Gdansk, Poland
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Pawelczyk T, Matecki A. Structural requirements of phospholipase C delta1 for regulation by spermine, sphingosine and sphingomyelin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 248:459-65. [PMID: 9346303 DOI: 10.1111/j.1432-1033.1997.00459.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We studied the relationship between sphingomyelin, calcium, spermine and sphingosine in regulation of phospholipase C (PLC) delta1 activity. Inhibition of PLC delta1 by sphingomyelin was promoted by spermine and Ca2+ and was partially abolished by sphingosine. The effect of sphingosine and spermine entirely depended on Ca2+. In the absence of Ca2+, no effect of these substances on PLC delta1 activity was observed. Using deletion mutants and active fragments of PLC delta1 generated by limited proteolysis, we have studied the structural requirements of the enzyme for regulation by these compounds. The deletion mutant of PLC delta1 lacking the first 58 amino acids and the mutant lacking the entire pleckstrin homology (PH) domain were fully active in the detergent assay, and their activities were affected by spermine, sphingosine, Ca2+ and sphingomyelin to the same extent as the native enzyme. The limited proteolysis of PLC delta1 generated two fragments of 40 kDa and 30 kDa, which formed a stable active complex. The relationship between Ca2+ concentration and enzymatic activity was almost identical for the native PLC delta1 and the proteolytic complex. The activity of the proteolytic complex formed by the 40 kDa and 30 kDa peptides was not affected by spermine and sphingosine. Sphingomyelin inhibited the complex slightly less than the native PLC delta1, and this inhibition was not promoted by spermine. These observations suggest that for activation of PLC delta1 by spermine and sphingosine, the region spanning domains of high conservation, named X and Y, must be intact. In contrast, the PH domain and the intact spanning region of the X and Y domains are not essential for inhibition of PLC delta1 by sphingomyelin.
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Affiliation(s)
- T Pawelczyk
- Department of Clinical Biochemistry, Medical University of Gdansk, Poland.
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