Artykuły w czasopismach: „Phospholipase C”

1

Hawrylak, K., i R. A. Stinson. "Phospholipase C and phosphatidylinositol phospholipase C." Clinical Chemistry 33, nr 2 (1.02.1987): 337. http://dx.doi.org/10.1093/clinchem/33.2.337.

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Bollag, Wendy B. "Role of phospholipases in adrenal steroidogenesis". Journal of Endocrinology 229, nr 1 (kwiecień 2016): R29—R41. http://dx.doi.org/10.1530/joe-16-0007.

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Phospholipases are lipid-metabolizing enzymes that hydrolyze phospholipids. In some cases, their activity results in remodeling of lipids and/or allows the synthesis of other lipids. In other cases, however, and of interest to the topic of adrenal steroidogenesis, phospholipases produce second messengers that modify the function of a cell. In this review, the enzymatic reactions, products, and effectors of three phospholipases, phospholipase C, phospholipase D, and phospholipase A2, are discussed. Although much data have been obtained concerning the role of phospholipases C and D in regulating adrenal steroid hormone production, there are still many gaps in our knowledge. Furthermore, little is known about the involvement of phospholipase A2, perhaps, in part, because this enzyme comprises a large family of related enzymes that are differentially regulated and with different functions. This review presents the evidence supporting the role of each of these phospholipases in steroidogenesis in the adrenal cortex.

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Dhand, Rajiv, Jared Young, Andelle Teng, Subbiah Krishnasamy i Nicholas J. Gross. "Is dipalmitoylphosphatidylcholine a substrate for convertase?" American Journal of Physiology-Lung Cellular and Molecular Physiology 278, nr 1 (1.01.2000): L19—L24. http://dx.doi.org/10.1152/ajplung.2000.278.1.l19.

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Convertase has homology with carboxylesterases, but its substrate(s) is not known. Accordingly, we determined whether dipalmitoylphosphatidylcholine (DPPC), the major phospholipid in surfactant, was a substrate for convertase. We measured [3H]choline release during cycling of the heavy subtype containing [3H]choline-labeled DPPC with convertase, phospholipases A2, B, C, and D, liver esterase, and elastase. Cycling with liver esterase or peanut or cabbage phospholipase D produced the characteristic profile of heavy and light peaks observed on cycling with convertase. In contrast, phospholipases A2, B, and C and yeast phospholipase D produced a broad band of radioactivity across the gradient without distinct peaks. [3H]choline was released when natural surfactant containing [3H]choline-labeled DPPC was cycled with yeast phospholipase D but not with convertase or peanut and cabbage phospholipases D. Similarly, yeast phospholipase D hydrolyzed [3H]choline from [3H]choline-labeled DPPC after incubation in vitro, whereas convertase, liver esterase, or peanut and cabbage phospholipases D did not. Thus convertase, liver esterase, and plant phospholipases D did not hydrolyze choline from DPPC either on cycling or during incubation with enzyme in vitro. In conclusion, conversion of heavy to light subtype of surfactant by convertase may require a phospholipase D type hydrolysis of phospholipids, but the substrate in this reaction is not DPPC.

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LITTLE, CLIVE. "Phospholipase C". Biochemical Society Transactions 17, nr 2 (1.04.1989): 271–73. http://dx.doi.org/10.1042/bst0170271.

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Karasawa, Tadahiro, Xingmin Wang, Tsuneo Maegawa, Yoshio Michiwa, Hiroyuki Kita, Koichi Miwa i Shinichi Nakamura. "Clostridium sordellii Phospholipase C: Gene Cloning and Comparison of Enzymatic and Biological Activities with Those of Clostridium perfringens and Clostridium bifermentans Phospholipase C". Infection and Immunity 71, nr 2 (luty 2003): 641–46. http://dx.doi.org/10.1128/iai.71.2.641-646.2003.

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ABSTRACT The gene encoding Clostridium sordellii phospholipase C (Csp) was cloned and expressed as a histidine-tagged (His-tag) protein, and the protein was purified to compare its enzymatic and biological activities with those of Clostridium perfringens phospholipase C (Cpa) and Clostridium bifermentans phospholipase C (Cbp). Csp was found to consist of 371 amino acid residues in the mature form and to be more homologous to Cbp than to Cpa. The egg yolk phospholipid hydrolysis activity of the His-tag Csp was about one-third of that of His-tag Cpa, but the hemolytic activity was less than 1% of that of His-tag Cpa. His-tag Csp was nontoxic to mice. Immunization of mice with His-tag Cbp or His-tag Csp did not provide effective protection against the lethal activity of His-tag Cpa. These results indicate that Csp possesses similar molecular properties to Cbp and suggest that comparative analysis of toxic and nontoxic clostridial phospholipases is helpful for characterization of the toxic properties of clostridial phospholipases.

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Teitelbaum, I. "Hormone signaling systems in inner medullary collecting ducts". American Journal of Physiology-Renal Physiology 263, nr 6 (1.12.1992): F985—F990. http://dx.doi.org/10.1152/ajprenal.1992.263.6.f985.

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The inner medullary collecting duct is a complex tissue that exhibits a variety of hormone signaling systems. These include the following: adenylyl cyclase activity stimulated by vasopressin (AVP), beta-adrenergic agonists, or prostanoids and inhibited by alpha 2-adrenergic agents or adenosine; guanylate cyclase activity in response to atrial natriuretic peptide (ANP); phospholipase C activity stimulated by ANP, AVP, bradykinin, endothelin, epidermal growth factor (EGF), and muscarinic cholinergic agents; and phospholipase A2 activity stimulated by AVP, bradykinin, EGF, and endothelin. The signal transduction mechanisms for each of these hormone signaling systems is succinctly reviewed, and the interactions between different signaling pathways are discussed. Central to this interaction is the mutually inhibitory relationship between activation of adenylyl cyclase and phospholipases. Increasing cellular adenosine 3',5'-cyclic monophosphate content impairs activation of phospholipases A2 and C; conversely, stimulation of phospholipase C impairs AVP-stimulated adenylyl cyclase activity via activation of protein kinase C.

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Ghannoum, Mahmoud A. "Potential Role of Phospholipases in Virulence and Fungal Pathogenesis". Clinical Microbiology Reviews 13, nr 1 (1.01.2000): 122–43. http://dx.doi.org/10.1128/cmr.13.1.122.

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SUMMARY Microbial pathogens use a number of genetic strategies to invade the host and cause infection. These common themes are found throughout microbial systems. Secretion of enzymes, such as phospholipase, has been proposed as one of these themes that are used by bacteria, parasites, and pathogenic fungi. The role of extracellular phospholipase as a potential virulence factor in pathogenic fungi, including Candida albicans, Cryptococcus neoformans, and Aspergillus, has gained credence recently. In this review, data implicating phospholipase as a virulence factor in C. albicans, Candida glabrata, C. neoformans, and A. fumigatus are presented. A detailed description of the molecular and biochemical approaches used to more definitively delineate the role of phospholipase in the virulence of C. albicans is also covered. These approaches resulted in cloning of three genes encoding candidal phospholipases (caPLP1, caPLB2, and PLD). By using targeted gene disruption, C. albicans null mutants that failed to secrete phospholipase B, encoded by caPLB1, were constructed. When these isogenic strain pairs were tested in two clinically relevant murine models of candidiasis, deletion of caPLB1 was shown to lead to attenuation of candidal virulence. Importantly, immunogold electron microscopy studies showed that C. albicans secretes this enzyme during the infectious process. These data indicate that phospholipase B is essential for candidal virulence. Although the mechanism(s) through which phospholipase modulates fungal virulence is still under investigations, early data suggest that direct host cell damage and lysis are the main mechanisms contributing to fungal virulence. Since the importance of phospholipases in fungal virulence is already known, the next challenge will be to utilize these lytic enzymes as therapeutic and diagnostic targets.

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Heo, Yunseok, Inhwan Lee, Sunjin Moon, Ji-Hye Yun, Eun Yu Kim, Sam-Yong Park, Jae-Hyun Park, Woo Taek Kim i Weontae Lee. "Crystal Structures of the Plant Phospholipase A1 Proteins Reveal a Unique Dimerization Domain". Molecules 27, nr 7 (2.04.2022): 2317. http://dx.doi.org/10.3390/molecules27072317.

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Phospholipase is an enzyme that hydrolyzes various phospholipid substrates at specific ester bonds and plays important roles such as membrane remodeling, as digestive enzymes, and the regulation of cellular mechanism. Phospholipase proteins are divided into following the four major groups according to the ester bonds they cleave off: phospholipase A1 (PLA1), phospholipase A2 (PLA2), phospholipase C (PLC), and phospholipase D (PLD). Among the four phospholipase groups, PLA1 has been less studied than the other phospholipases. Here, we report the first molecular structures of plant PLA1s: AtDSEL and CaPLA1 derived from Arabidopsis thaliana and Capsicum annuum, respectively. AtDSEL and CaPLA1 are novel PLA1s in that they form homodimers since PLAs are generally in the form of a monomer. The dimerization domain at the C-terminal of the AtDSEL and CaPLA1 makes hydrophobic interactions between each monomer, respectively. The C-terminal domain is also present in PLA1s of other plants, but not in PLAs of mammals and fungi. An activity assay of AtDSEL toward various lipid substrates demonstrates that AtDSEL is specialized for the cleavage of sn-1 acyl chains. This report reveals a new domain that exists only in plant PLA1s and suggests that the domain is essential for homodimerization.

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Kadamur, Ganesh, i Elliott M. Ross. "Mammalian Phospholipase C". Annual Review of Physiology 75, nr 1 (10.02.2013): 127–54. http://dx.doi.org/10.1146/annurev-physiol-030212-183750.

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Alvarez-Breckenridge, Christopher A., Kristin A. Waite i Charis Eng. "PTEN regulates phospholipase D and phospholipase C". Human Molecular Genetics 16, nr 10 (3.04.2007): 1157–63. http://dx.doi.org/10.1093/hmg/ddm063.

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Tanabe, Kumiko, Osamu Kozawa, Hiroyuki Matsuno, Masayuki Niwa, Shuji Dohi i Toshihiko Uematsu. "Effect of Propofol on Arachidonate Cascade by Vasopressin in Aortic Smooth Muscle Cells". Anesthesiology 90, nr 1 (1.01.1999): 215–24. http://dx.doi.org/10.1097/00000542-199901000-00028.

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Background The mechanisms underlying the vascular effects of propofol are not fully understood. Vasopressin, a potent vasoactive peptide, stimulates the arachidonate cascade and the synthesis of prostacyclin (PGI2; the main metabolite of the cascade in vascular smooth muscle cells). Arachidonic acid (AA) release by phospholipases is the rate-limiting step in the cascade. We investigated the mechanisms underlying vasopressin-induced AA release and the effect of propofol on PGI2 synthesis in a rat aortic smooth muscle cell line: A10 cells. Methods In cultured A10 cells pretreated with propofol, the stimulation by vasopressin of AA release and PGI2 synthesis was evaluated by measuring [3H]AA and 6-keto PGF1alpha, respectively, in the culture medium. The effects of propofol on vasopressin-induced activation of phosphoinositide-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D were evaluated by measuring inositol phosphate formation and choline formation, respectively. Results A phospholipase C inhibitor and a phosphatidic acid phosphohydrolase inhibitor both attenuated vasopressin-induced AA release and PGI2 synthesis, as did a phospholipase A2 inhibitor. Propofol inhibited vasopressin-induced activation of phosphoinositide-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D, but this effect of propofol was significant only at supraclinical concentration (0.1 mM). Propofol reduced vasopressin-induced PGI2 synthesis. The inhibitory effect was observed at concentrations (10 microM-0.1 mM) higher than those used clinically. Conclusions Propofol suppresses the arachidonate cascade caused by vasopressin at least partly by inhibiting phosphoinositide-hydrolyzing phospholipase C and phosphatidylcholine-hydrolyzing phospholipase D, resulting in the inhibition of PGI2 synthesis. Propofol-mediated inhibition of vasopressin-stimulated synthesis of PGI2 may reduce the vasorelaxation by propofol.

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Kunze, Donika, Inga Melzer, Désirée Bennett, Dominique Sanglard, Donna MacCallum, Jan Nörskau, David C. Coleman, Frank C. Odds, Wilhelm Schäfer i Bernhard Hube. "Functional analysis of the phospholipase C gene CaPLC1 and two unusual phospholipase C genes, CaPLC2 and CaPLC3, of Candida albicans". Microbiology 151, nr 10 (1.10.2005): 3381–94. http://dx.doi.org/10.1099/mic.0.28353-0.

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Phospholipases C are known to be important regulators of cellular processes but may also act as virulence factors of pathogenic microbes. At least three genes in the genome of the human-pathogenic fungus Candida albicans encode phospholipases with conserved phospholipase C (Plc) motifs. None of the deduced protein sequences contain N-terminal signal peptides, suggesting that these phospholipases are not secreted. In contrast to its orthologue in Sacharomyces cerevisiae, CaPLC1 seems to be an essential gene. However, a conditional mutant with reduced transcript levels of CaPLC1 had phenotypes similar to Plc1p-deficient mutants in S. cerevisiae, including reduced growth on media causing increased osmotic stress, on media with a non-glucose carbon source, or at elevated or lower temperatures, suggesting that CaPlc1p, like the Plc1p counterpart in S. cerevisiae, may be involved in multiple cellular processes. Furthermore, phenotypic screening of the heterozygous ΔCaplc1/CaPLC1 mutant showed additional defects in hyphal formation. The loss of CaPLC1 cannot be compensated by two additional PLC genes of C. albicans (CaPLC2 and CaPLC3) encoding two almost identical phospholipases C with no counterpart in S. cerevisiae but containing structural elements found in bacterial phospholipases C. Although the promoter sequences of CaPLC2 and CaPLC3 differed dramatically, the transcriptional pattern of both genes was similar. In contrast to CaPLC1, CaPLC2 and CaPLC3 are not essential. Although Caplc2/3 mutants had reduced abilities to produce hyphae on solid media, these mutants were as virulent as the wild-type in a model of systemic infection. These data suggest that C. albicans contains two different classes of phospholipases C which are involved in cellular processes but which have no specific functions in pathogenicity.

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Inamori, K., N. Sagawa, M. Hasegawa, H. Itoh, J. Yano i T. Mori. "Activation of phospholipase D in cultured human amnion cells". Reproduction, Fertility and Development 7, nr 6 (1995): 1591. http://dx.doi.org/10.1071/rd9951591.

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The regulation of phospholipase D (PLD) activity in the human amniotic membrane was examined using primary cultures of amnion cells. Cultured amnion cells were labelled with [3H]oleic acid, and PLD activity was determined as the amount of [3H]phosphatidylethanol (PEt) produced during incubation in the presence of 0.1% ethanol. PLD activity in cultured amnion cells was activated by addition of arginine vasopressin and oxytocin. PLD activity was also stimulated by treatment was arachidonic acid, the product of phospholipase A2 (PLA2), and phospholipase C (PLC). These results indicate that PLD in amnion cells is activated by substances present in amniotic fluid, and that cross-talk between phospholipases A2, C and D may occur in amnion cells.

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D'Eça Júnior, Aurean, Anderson França Silva, Fernanda Costa Rosa, Sílvio Gomes Monteiro, Patrícia de Maria Silva Figueiredo i Cristina de Andrade Monteiro. "In vitro differential activity of phospholipases and acid proteinases of clinical isolates of Candida". Revista da Sociedade Brasileira de Medicina Tropical 44, nr 3 (10.06.2011): 334–38. http://dx.doi.org/10.1590/s0037-86822011005000036.

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INTRODUCTION: Candida yeasts are commensals; however, if the balance of normal flora is disrupted or the immune defenses are compromised, Candida species can cause disease manifestations. Several attributes contribute to the virulence and pathogenicity of Candida, including the production of extracellular hydrolytic enzymes, particularly phospholipase and proteinase. This study aimed to investigate the in vitro activity of phospholipases and acid proteinases in clinical isolates of Candida spp. METHODS: Eighty-two isolates from hospitalized patients collected from various sites of origin were analyzed. Phospholipase production was performed in egg yolk medium and the production of proteinase was verified in a medium containing bovine serum albumin. The study was performed in triplicate. RESULTS: Fifty-six (68.3%) of isolates tested were phospholipase positive and 16 (44.4%) were positive for proteinase activity. C. tropicalis was the species with the highest number of positive isolates for phospholipase (91.7%). Statistically significant differences were observed in relation to production of phospholipases among species (p<0,0001) and among the strains from different sites of origin (p=0.014). Regarding the production of acid protease, the isolates of C. parapsilosis tested presented a larger number of producers (69.2%). Among the species analyzed, the percentage of protease producing isolates did not differ statistically (χ2=1.9 p=0.5901 (χ2=1.9 p=0.5901). CONCLUSIONS: The majority of C. non-albicans and all C. albicans isolates were great producers of hydrolytic enzymes and, consequently, might be able to cause infection under favorable conditions.

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Umemura, Atsushi, Hideo Mabe, Hajime Nagai i Fumihiko sugino. "Action of phospholipases A2 and C on free fatty acid release during complete ischemia in rat neocortex". Journal of Neurosurgery 76, nr 4 (kwiecień 1992): 648–51. http://dx.doi.org/10.3171/jns.1992.76.4.0648.

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✓ The levels of brain free fatty acids rapidly increase after the onset of ischemia. The purpose of this study was to investigate the action of phospholipases A2 and C during complete ischemia based on the effects of a phospholipase C inhibitor (phenylmethylsulfonyl fluoride) and the N-methyl-D-aspartate antagonist MK-801 on the release of free fatty acids in rat neocortex. Complete brain ischemia was induced in rats with cardiac arrest by intracardiac injection of KC1. Free fatty acid levels in the neocortex were measured 0, 2, 4, and 8 minutes after cardiac arrest. Phenylmethylsulfonyl fluoride inhibited the release of free fatty acids primarily from phosphatidylinositol during the first 2 minutes of ischemia and from phosphatidylcholine and phosphatidylethanolamine at 4 to 8 minutes of ischemia. Conversely, MK-801 inhibited free fatty acid release mainly from phosphatidylcholine and phosphatidylethanolamine at 2 to 4 minutes of ischemia. These results indicate that the release of free fatty acids during the first 2 minutes of ischemia can be attributed mostly to the action of phospholipase C, and that the activation of phospholipase C further influences the activation of phospholipase A2 in the subsequent course, while phospholipase A2 predominantly acts after 2 minutes of ischemia.

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Cross, M. J., M. N. Hodgkin, S. Roberts, E. Landgren, M. J. Wakelam i L. Claesson-Welsh. "Tyrosine 766 in the fibroblast growth factor receptor-1 is required for FGF-stimulation of phospholipase C, phospholipase D, phospholipase A(2), phosphoinositide 3-kinase and cytoskeletal reorganisation in porcine aortic endothelial cells". Journal of Cell Science 113, nr 4 (15.02.2000): 643–51. http://dx.doi.org/10.1242/jcs.113.4.643.

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Fibroblast growth factor-mediated signalling was studied in porcine aortic endothelial cells expressing either wild-type fibroblast growth factor receptor-1 or a mutant receptor (Y766F) unable to bind phospholipase C-(γ). Stimulation of cells expressing the wild-type receptor resulted in activation of phospholipases C, D and A(2) and increased phosphoinositide 3-kinase activity. Stimulation of the wild-type receptor also resulted in stress fibre formation and a cellular shape change. Cells expressing the Y766F mutant receptor failed to stimulate phospholipase C, D and A(2) as well as phosphoinositide 3-kinase. Furthermore, no stress fibre formation or shape change was observed. Both the wild-type and Y766F receptor mutant activated MAP kinase and elicited proliferative responses in the porcine aortic endothelial cells. Thus, fibroblast growth factor receptor-1 mediated activation of phospholipases C, D and A(2) and phosphoinositide 3-kinase was dependent on tyrosine 766. Furthermore, whilst tyrosine 766 was not required for a proliferative response, it was required for fibroblast growth factor receptor-1 mediated cytoskeletal reorganisation.

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González-Mendoza, Víctor M., M. E. Sánchez-Sandoval, Lizbeth A. Castro-Concha i S. M. Teresa Hernández-Sotomayor. "Phospholipases C and D and Their Role in Biotic and Abiotic Stresses". Plants 10, nr 5 (4.05.2021): 921. http://dx.doi.org/10.3390/plants10050921.

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Plants, as sessile organisms, have adapted a fine sensing system to monitor environmental changes, therefore allowing the regulation of their responses. As the interaction between plants and environmental changes begins at the surface, these changes are detected by components in the plasma membrane, where a molecule receptor generates a lipid signaling cascade via enzymes, such as phospholipases (PLs). Phospholipids are the key structural components of plasma membranes and signaling cascades. They exist in a wide range of species and in different proportions, with conversion processes that involve hydrophilic enzymes, such as phospholipase-C (PLC), phospholipase-D (PLD), and phospholipase-A (PLA). Hence, it is suggested that PLC and PLD are highly conserved, compared to their homologous genes, and have formed clusters during their adaptive history. Additionally, they generate responses to different functions in accordance with their protein structure, which should be reflected in specific signal transduction responses to environmental stress conditions, including innate immune responses. This review summarizes the phospholipid systems associated with signaling pathways and the innate immune response.

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Bomalaski, John S., Fusao Hirata i Mike A. Clark. "Aspirin inhibits phospholipase C". Biochemical and Biophysical Research Communications 139, nr 1 (sierpień 1986): 115–21. http://dx.doi.org/10.1016/s0006-291x(86)80087-0.

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Wahl, Matthew, i Graham Carpenter. "Selective phospholipase C activation". BioEssays 13, nr 3 (marzec 1991): 107–13. http://dx.doi.org/10.1002/bies.950130303.

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Fisher, Isaac J., Kaushik Muralidharan, Kennedy Outlaw i Elisabeth Garland-Kuntz. "Resolving phospholipase C regulation". Acta Crystallographica Section A Foundations and Advances 79, a1 (7.07.2023): a22. http://dx.doi.org/10.1107/s2053273323099771.

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BERTELLO, Laura E., Maria Júlia M. ALVES, Walter COLLI i Rosa M. de LEDERKREMER. "Evidence for phospholipases from Trypanosoma cruzi active on phosphatidylinositol and inositolphosphoceramide". Biochemical Journal 345, nr 1 (17.12.1999): 77–84. http://dx.doi.org/10.1042/bj3450077.

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The lipid moiety in the glycosylphosphatidylinositol anchors of glycoproteins of Trypanosoma cruzi consists of an alkylacylglycerol, a lysoalkylglycerol or a ceramide. Previously, we showed that the inositolphosphoceramides (IPCs) are the major components in the precursor inositolphospholipids of epimastigote and trypomastigote forms. Using 3H-labelled subfractions of IPC, phosphatidylinositol (PI) and glycoinositolphospholipids (GIPLs) as substrates with a cell-free system, we now demonstrate the association of at least five enzyme activities with the trypanosomal membranous particulate material. These include: phospholipase A1 and phospholipase A2, enzymes that release free fatty acid from the PI and GIPLs; an acyltransferase responsible for the acylation of the generated monoacyl or monoalkylglycerolipids with endogenous unlabelled fatty acid; two activities of phospholipase C, one releasing ceramide from IPC and the other alkylacylglycerol, alkylglycerol or diacylglycerol from PI. The neutral lipids were also generated on incubation of the GIPLs. The phospholipase C activities were inhibited by p-chloromercuriphenylsulphonic acid, as reported for other PI phospholipases C. An IPC-fatty-acid hydrolase, releasing fatty acid from the labelled IPC, was also observed. The enzyme activities reported in the present study may be acting in remodelling reactions leading to the anchor of the mature glycoproteins of T. cruzi.

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Cockcroft, S., i J. Stutchfield. "The receptors for ATP and fMetLeuPhe are independently coupled to phospholipases C and A2 via G-protein(s). Relationship between phospholipase C and A2 activation and exocytosis in HL60 cells and human neutrophils". Biochemical Journal 263, nr 3 (1.11.1989): 715–23. http://dx.doi.org/10.1042/bj2630715.

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The relationship between phospholipase A2 and C activation and secretion was investigated in intact human neutrophils and differentiated HL60 cells. Activation by either ATP or fMetLeuPhe leads to [3H]arachidonic acid release into the external medium from prelabelled cells. This response was inhibited when the cells were pretreated with pertussis toxin. When the [3H]arachidonic acid-labelled cells were stimulated with fMetLeuPhe, ATP or Ca2+ ionophore A23187, and the lipids analysed by t.l.c., the increase in free fatty acid was accompanied by decreases in label from phosphatidylinositol and phosphatidylcholine. Moreover, incorporation of label into triacylglycerol and to a lesser extent phosphatidylethanolamine was evident. Activation of secretion was evident with ATP and fMetLeuPhe but not with A23187. The pharmacological specificity of the ATP receptor in HL60 cells was investigated by measuring secretion of beta-glucuronidase, formation of inositol phosphatases and release of [3H]arachidonic acid. External addition of ATP, UTP, ITP, adenosine 5′-[gamma-thio]triphosphate (ATP[S]), adenosine 5′-[beta gamma-imido]triphosphate (App[NH]p), XTP, CTP, GTP, 8-bromo-ATP and guanosine 5′-[gamma-thio]triphosphate (GTP[S]) to intact HL60 cells stimulated inositol phosphate production, but only the first five nucleotides were effective at stimulating secretion or [3H]arachidonic acid release. In human neutrophils, addition of ATP, ITP, UTP and ATP[S] also stimulated secretion from specific and azurophilic granules, and this was accompanied by increases in cytosolic Ca2+ and in [3H]arachidonic acid release. The addition of phorbol 12-myristate 13-acetate (PMA; 1 nM) prior to the addition of either fMetLeuPhe or ATP led to inhibition of phospholipase C activity. In contrast, this had no effect on phospholipase A2 activation, whilst secretion was potentiated. Phospholipase A2 activation by either agonist was dependent on an intact cell metabolism, as was secretion. It is concluded that (1) activation of phospholipase C does not always lead to activation of phospholipase A2, (2) phospholipase A2 is coupled to the receptor independently of phospholipase C via a pertussis-toxin-sensitive G-protein and (3) for secretion to take place, the receptor has to activate both phospholipases C and A2.

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Liu, M., J. Xu, J. Liu, M. E. Kraw, A. K. Tanswell i M. Post. "Mechanical strain-enhanced fetal lung cell proliferation is mediated by phospholipase C and D and protein kinase C". American Journal of Physiology-Lung Cellular and Molecular Physiology 268, nr 5 (1.05.1995): L729—L738. http://dx.doi.org/10.1152/ajplung.1995.268.5.l729.

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The signaling pathways by which intermittent strain (60 cycles/min, 15 min/h) regulates proliferation of mixed fetal rat lung cell in vitro have been investigated. Adenosine 3',5'-cyclic monophosphate (cAMP) content and cAMP-dependent protein kinase (PKA) activity were not affected by strain. The stimulatory effect of strain on DNA synthesis was also not influenced by the cyclic nucleotide-dependent protein kinase inhibitors H-8 or HA-1004, the adenylate cyclase inhibitor SQ-22536, or a PKA inhibitor and cAMP antagonist, adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS). In contrast, intracellular concentrations of two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), were dramatically increased after a short period of strain. This increase in second messengers was accompanied by an increased tyrosine phosphorylation of phospholipase C-gamma 1. Phospholipase D activity was also increased by strain. Mechanical strain elicited a shift in the subcellular distribution of PKC activity from cytosol to membranes shortly after the onset of strain. The specific activity of PKC in the membranes increased 6- to 10-fold within 5-15 min and remained increased throughout a 48-h period of intermittent strain. Strain-induced PKC activation and DNA synthesis were blocked by the PKC inhibitors H-7, staurosporine, and calphostin C, as well as by the phospholipase C inhibitor U-73,122. We conclude that mechanical strain of mixed fetal rat lung cells activates phospholipid turnover via phospholipases, followed by PKC activation, which then triggers the downstream events that lead to cell proliferation.

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Watkins, D. C., C. M. Moxham, A. J. Morris i C. C. Malbon. "Suppression of Giα2 enhances phospholipase C signalling". Biochemical Journal 299, nr 3 (1.05.1994): 593–96. http://dx.doi.org/10.1042/bj2990593.

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G-proteins mediate transmembrane signalling from a populous group of cell-surface receptors to a smaller group of effectors that includes adenylate cyclase, various ion channels and phospholipase C. Stem cells (F9 teratocarcinoma) or rat osteosarcoma 17/2.8 cells in which Gi alpha 2 expression is abolished by antisense RNA display markedly elevated basal inositol 1,4,5-trisphosphate accumulation and a potentiated phospholipase C response to stimulatory hormones. Expression of the Q205L mutant of Gi alpha 2, which is constitutively active, was found to block persistently hormonally stimulated phospholipase C activity, implicating Gi alpha 2 as an inhibitory regulator of phospholipase C signalling. Analysis using Gi alpha 2-deficient adipocytes of transgenic mice provided further evidence for a role for Gi alpha 2 in phospholipase C regulation, demonstrating in vivo that loss of Gi alpha 2 elevates basal, and markedly potentiates hormonally stimulated, phospholipase C activity. This report demonstrates for the first time that a single G-protein, G12, can regulate two distinct signalling pathways, i.e. adenylate cyclase and phospholipase C.

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25

Sharom, Frances J., Gary L. McNeil, John R. Glover i Sandra Seier. "Modulation of the cleavage of glycosylphosphatidylinositol-anchored proteins by specific bacterial phospholipases". Biochemistry and Cell Biology 74, nr 5 (1.09.1996): 701–13. http://dx.doi.org/10.1139/o96-077.

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Many enzymes are tethered to the extracellular face of the plasma membrane by a glycosylphosphatidylinositol (GPI) anchor. These proteins can be released in soluble form by the action of GPI-specific phospholipases. Little is currently known about the factors modulating this release. We investigated the effects of several experimental variables on the cleavage of the GPI-anchored proteins 5′-nucleotidase, acetylcholinesterase, and alkaline phosphatase by phospholipases from Bacillus thuringiensis and Staphylococcus aureus. Phospholipase activity was not inhibited by isotonic salt and was relatively unaffected by buffer type and concentration. In both cases, the optimum pH for cleavage was ~ 6.5. Over 80% of 5′-nucleotidase activity present in the lymphocyte plasma membrane was cleaved by the B. thuringiensis enzyme, and the initial rate of release was linear with phospholipase concentration. All three GPI-anchored proteins were released from lymphocyte plasma membrane at comparable phospholipase concentrations, suggesting that they have similar anchor structures. The catalytic activity of 5′-nucleotidase appeared to increase following conversion to the soluble form. The relative surface charge of the host plasma membrane modulated catalytic activity towards GPI-anchored proteins, depending on the net charge of the phospholipase. Studies on purified lymphocyte 5′-nucleotidase reconstituted into bilayers of dimyristoylphosphatidylcholine indicated that the efficiency of phospholipase cleavage was 12- to 50-fold lower when compared with the native plasma membrane. The ability of the phospholipase to cleave the GPI anchor was further reduced when the bilayer was in the gel phase.Key words: glycosylphosphatidylinositol anchor, phospholipase C, 5′-nucleotidase, acetylcholinesterase, alkaline phosphatase.

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26

Krjukova, Jelena, Tomas Holmqvist, Alexander S. Danis, Karl E. O. Åkerman i Jyrki P. Kukkonen. "Phospholipase C activator m -3M3FBS affects Ca2+ homeostasis independently of phospholipase C activation". British Journal of Pharmacology 143, nr 1 (wrzesień 2004): 3–7. http://dx.doi.org/10.1038/sj.bjp.0705911.

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Kiss, Zoltan, i Nandor Garamszegi. "Protein kinase C-dependent stimulation of phospholipase D in phospholipase C-treated fibroblasts". Lipids 28, nr 6 (czerwiec 1993): 479–81. http://dx.doi.org/10.1007/bf02536077.

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Bominaar, A. A., i P. J. Van Haastert. "Chemotactic antagonists of cAMP inhibit Dictyostelium phospholipase C". Journal of Cell Science 104, nr 1 (1.01.1993): 181–85. http://dx.doi.org/10.1242/jcs.104.1.181.

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In Dictyostelium discoideum extracellular cAMP induces chemotaxis via a transmembrane signal transduction cascade consisting of surface cAMP receptors, G-proteins and effector enzymes including adenylyl cyclase, guanylyl cyclase and phospholipase C. Previously it was demonstrated that some cAMP derivatives such as 3′-deoxy-3′-aminoadenosine 3′:5′-monophosphate (3′NH-cAMP) bind to the receptor and induce normal activation of adenylyl cyclase and guanylyl cyclase. However these analogues do not induce chemotaxis, probably because the signal is transduced in an inappropriate manner. We have now studied the regulation of phospholipase C by cAMP and these chemotactic antagonists. cAMP induced the two-fold activation of phospholipase C leading to a transient increase of Ins(1,4,5)P3 levels. In contrast, the analogues induced a rapid decrease of intracellular Ins(1,4,5)P3 levels, due to the inhibition of phospholipase C activity. In a transformed cell-line lacking the G-protein that mediates phospholipase C inhibition, 3′NH-cAMP did not decrease phospholipase C activity and was no longer an antagonist of chemotaxis. These results suggest that inhibition of phospholipase C leads to aberrant chemotaxis.

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29

Kolesnikov, Y. S., S. V. Kretynin, V. S. Kravets i Y. K. Bukhonska. "Phosphatidic acid formation and signaling in plant cells". Ukrainian Biochemical Journal 96, nr 1 (23.02.2024): 5–21. http://dx.doi.org/10.15407/ubj96.01.005.

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This review conteins updated information on the structure, localization and regulation of phosphatidic acid (PA)-producing enzymes phospholipase D, phosphoinositide-specific and non-specific phospholipases C and diacylglycerol kinases is analyzed. The specific role of PA and PA-producing enzymes in plant stress signaling is discussed.

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30

Rupwate, Sunny D., i Ram Rajasekharan. "Plant phosphoinositide-specific phospholipase C". Plant Signaling & Behavior 7, nr 10 (październik 2012): 1281–83. http://dx.doi.org/10.4161/psb.21436.

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Goñi, Félix M., José L. Nieva, Gorka Basañez, Gerardo Fidelio i Alicia Alonso. "Phospholipase-C-promoted liposome fusion". Biochemical Society Transactions 22, nr 3 (1.08.1994): 839–44. http://dx.doi.org/10.1042/bst0220839.

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Williams, Roger L. "Mammalian phosphoinositide-specific phospholipase C". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids 1441, nr 2-3 (listopad 1999): 255–67. http://dx.doi.org/10.1016/s1388-1981(99)00150-x.

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Cocco, Lucio, Alberto M. Martelli, R. Stewart Gilmour, Sue Goo Rhee i Francesco A. Manzoli. "Nuclear phospholipase C and signaling". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids 1530, nr 1 (styczeń 2001): 1–14. http://dx.doi.org/10.1016/s1388-1981(00)00169-4.

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Jones, Gwenith, i Graham Carpenter. "Regulation of phospholipase C isozymes". Progress in Growth Factor Research 4, nr 2 (styczeń 1992): 97–106. http://dx.doi.org/10.1016/0955-2235(92)90025-d.

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Eberhard, David A., i Ronald W. Holz. "Intracellular Ca2+ activates phospholipase C". Trends in Neurosciences 11, nr 12 (styczeń 1988): 517–20. http://dx.doi.org/10.1016/0166-2236(88)90174-9.

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Kostadinova, S. "Phospholipase C fromPseudomonas FluorescensStrain B". Biotechnology & Biotechnological Equipment 11, nr 3-4 (styczeń 1997): 38–42. http://dx.doi.org/10.1080/13102818.1997.10818951.

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Horowitz, Lisa F., Wiebke Hirdes, Byung-Chang Suh, Donald W. Hilgemann, Ken Mackie i Bertil Hille. "Phospholipase C in Living Cells". Journal of General Physiology 126, nr 3 (29.08.2005): 243–62. http://dx.doi.org/10.1085/jgp.200509309.

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We have further tested the hypothesis that receptor-mediated modulation of KCNQ channels involves depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) by phosphoinositide-specific phospholipase C (PLC). We used four parallel assays to characterize the agonist-induced PLC response of cells (tsA or CHO cells) expressing M1 muscarinic receptors: translocation of two fluorescent probes for membrane lipids, release of calcium from intracellular stores, and chemical measurement of acidic lipids. Occupation of M1 receptors activates PLC and consumes cellular PIP2 in less than a minute and also partially depletes mono- and unphosphorylated phosphoinositides. KCNQ current is simultaneously suppressed. Two inhibitors of PLC, U73122 and edelfosine (ET-18-OCH3), can block the muscarinic actions completely, including suppression of KCNQ current. However, U73122 also had many side effects that were attributable to alkylation of various proteins. These were mimicked or occluded by prior reaction with the alkylating agent N-ethylmaleimide and included block of pertussis toxin–sensitive G proteins and effects that resembled a weak activation of PLC or an inhibition of lipid kinases. By our functional criteria, the putative PLC activator m-3M3FBS did stimulate PLC, but with a delay and an irregular time course. It also suppressed KCNQ current. The M1 receptor–mediated activation of PLC and suppression of KCNQ current were stopped by lowering intracellular calcium well below resting levels and were slowed by not allowing intracellular calcium to rise in response to PLC activation. Thus calcium release induced by PLC activation feeds back immediately on PLC, accelerating it during muscarinic stimulation in strong positive feedback. These experiments clarify important properties of receptor-coupled PLC responses and their inhibition in the context of the living cell. In each test, the suppression of KCNQ current closely paralleled the expected fall of PIP2. The results are described by a kinetic model.

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38

Nakamura, Yuki, i Anh H. Ngo. "Correction to: Non-specific phospholipase C (NPC): an emerging class of phospholipase C in plant growth and development". Journal of Plant Research 134, nr 2 (5.02.2021): 365. http://dx.doi.org/10.1007/s10265-020-01251-7.

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Tsutsumi, T., T. Kobayashi, M. Miyashita, S. Watanabe, Y. Homma i H. Okuyama. "A Lysophosphoinositide-Specific Phospholipase C Distinct from Other Phospholipase C Families in Rat Brain". Archives of Biochemistry and Biophysics 317, nr 2 (marzec 1995): 331–36. http://dx.doi.org/10.1006/abbi.1995.1171.

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Singer, William D., H. Alex Brown, and i Paul C. Sternweis. "REGULATION OF EUKARYOTIC PHOSPHATIDYLINOSITOL-SPECIFIC PHOSPHOLIPASE C AND PHOSPHOLIPASE D". Annual Review of Biochemistry 66, nr 1 (czerwiec 1997): 475–509. http://dx.doi.org/10.1146/annurev.biochem.66.1.475.

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Wang, Z. "Phospholipase C- 1: A Phospholipase and Guanine Nucleotide Exchange Factor". Molecular Interventions 2, nr 6 (1.10.2002): 352–55. http://dx.doi.org/10.1124/mi.2.6.352.

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Goñi, Félix M., i Alicia Alonso. "Membrane Fusion Induced by Phospholipase C and Sphingomyelinases". Bioscience Reports 20, nr 6 (1.12.2000): 443–63. http://dx.doi.org/10.1023/a:1010450702670.

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In the past decade lipid vesicle fusion induced by either bacterial PC-preferring phospholipase C, phosphatidylinositol-specific phospholipase C, sphingomyelinase, or a combination of phospholipase C and sphingomyelinase has been demonstrated. In the present paper, the experimental evidence is reviewed, and discussed in terms of the underlying molecular mechanisms of fusion, and of the possible physiological relevance of these findings.

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43

Badiani, K., i G. Arthur. "Evidence for receptor and G-protein regulation of a phosphatidylethanolamine-hydrolysing phospholipase A1 in guinea-pig heart microsomes: stimulation of phospholipase A1 activity by DL-isoprenaline and guanine nucleotides". Biochemical Journal 312, nr 3 (15.12.1995): 805–9. http://dx.doi.org/10.1042/bj3120805.

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While evidence has been presented for the receptor-mediated activation of phospholipases A2, C and D, the activation of phospholipase A1 subsequent to receptor activation has not been established. Phospholipase A1-catalysed hydrolysis of 1-palmitoyl-2-linoleoyl-glycerophosphoethanolamine (GPE) by guinea-pig heart microsomes was stimulated 40-60% by isoprenaline. This isoprenaline-mediated increase in activity was blocked by propranolol and butoxamine, a specific beta 2-adrenergic antagonist, but not by atenolol, a specific beta 1-adrenergic antagonist. Neither clonidine nor phenylephrine, alpha 1- and alpha 2-adrenergic agonists respectively, had a stimulatory effect on the hydrolysis of the PE substrate. Guanosine 5′(-)[gamma-thio]triphosphate (GTP[S]) and guanosine 5′(-)[beta, gamma-imido]triphosphate, but not guanosine 5′(-)[beta-thio]diphosphate (GDP[S]) or adenosine 5′(-)[gamma-thio]triphosphate, stimulated the hydrolysis of 1-palmitoyl-2-linoleoyl-GPE by phospholipase A1. GDP[S] inhibited the isoprenaline-mediated stimulation of phospholipase A1 activity. Phospholipase A1 hydrolysis of 1-palmitoyl-2-linoleoyl-GPE was not dependent on cations; however, the stimulatory effects of isoprenaline and GTP[S] on the hydrolytic activity were abolished by cation chelators. The above data suggest that phospholipase A1 activity in guinea-pig heart microsomes is activated by the binding of isoprenaline to beta 2-adrenergic receptors. Furthermore the stimulation of phospholipase A1 activity by the agonist may be mediated via activation of G-proteins.

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Mahadevappa, V. G., i Frank Sicilia. "Mobilization of arachidonic acid in thrombin-stimulated human platelets". Biochemistry and Cell Biology 68, nr 2 (1.02.1990): 520–27. http://dx.doi.org/10.1139/o90-074.

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In the present work we investigated the effect of serine esterase inhibitors such as 2-nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC) and phenylmethylsulfonyl fluoride (PMSF), as well as the effect of mepacrine on thrombin-induced mobilization of arachidonic acid (AA) in human platelets. The inhibitor NCDC (0.6 mM) completely abolished the thrombin-induced activation of phospholipase C, phospholipase A2, and transacylase enzymes, whereas the pretreatment of platelets with PMSF (2 mM) resulted in a highly selective inhibition of phospholipase A2 and transacylase activities, with no marked effect on thrombin-induced activation of phospholipase C. The thrombin-induced release of [3H]AA from phosphatidylcholine and phosphatidylinositol was reduced by 90 and 56%, respectively, in the presence of PMSF. This inhibitor also caused a parallel inhibition in the accumulation of [3H]AA (85%) with little effect on thrombin-induced formation of [3H]phosphatidic acid (5%), whereas mepacrine (0.4 mM) caused a selective inhibition of phospholipase A2 and transacylase activities with concomitant stimulation of [3H]phosphatidic acid formation in intact human platelets. These results demonstrate that NCDC and PMSF (serine esterase inhibitors) do not affect agonist-induced activation of phospholipases that mobilize arachidonic acid through a common site. Our results further demonstrate that the inhibition of [3H]AA release observed in the presence of NCDC, PMSF, and mepacrine is primarily due to their direct effects on enzyme activities, rather than due to their indirect effects through formation of complexes between inhibitors and membrane phospholipids. Based upon these results, we also conclude that the combined hydrolysis of phosphatidylcholine and phosphatidylinositol by phospholipase A2 serves as a major source for eicosanoid biosynthesis in thrombin-stimulated human platelets.Key words: deacylation, phospholipids, thrombin, platelets, phospholipase A2.

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45

Ganendren, Ranjini, Fred Widmer, Vatsala Singhal, Christabel Wilson, Tania Sorrell i Lesley Wright. "In Vitro Antifungal Activities of Inhibitors of Phospholipases from the Fungal Pathogen Cryptococcus neoformans". Antimicrobial Agents and Chemotherapy 48, nr 5 (maj 2004): 1561–69. http://dx.doi.org/10.1128/aac.48.5.1561-1569.2004.

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ABSTRACT Secreted phospholipase B is a proven virulence factor for the pathogenic fungus Cryptococcus neoformans and exhibits three phospholipase activities in the one protein. These are phospholipase B (PLB), lysophospholipase (LPL), and lysophospholipase transacylase (LPTA). Our aim was to investigate the feasibility of using this enzyme as a target for antifungal therapy. We determined in C. neoformans var. grubii strain H99 that 82% of PLB activity was secreted but that 64% of LPL activity and 70% of LPTA activity were cell associated. Cell-associated activities (cytosolic and membrane) were further characterized, since it is likely that any fungicidal effect would depend on inhibition of these enzymes. Four commercially available compounds with structural similarities to phospholipid substrates were tested as inhibitors. These were alexidine dihydrochloride (compound A), dioctadecyldimethylammonium bromide (compound O), 1,12 bis-(tributylphosphonium)dodecane dibromide (compound P), and decamethonium dibromide (compound D). The best phospholipase inhibitors (compounds A and P) were also the most potent antifungal agents by the standard broth microdilution test. Compound A was highly selective for secreted and cell-associated PLB activities and showed no inhibition of mammalian phospholipase A 2 at 0.25 μM. Compound O, which was specific for secretory and cytosolic LPL and LPTA and membrane-associated PLB, was not antifungal. We conclude that inhibitors of cryptococcal phospholipases can be selective for fungal enzymes and intrinsically antifungal. They also provide tools for assessing the relative importance of the various enzyme activities in virulence. Our results enable further rational structure-function studies to validate the use of phospholipases as antifungal targets.

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Purkiss, J. R., i M. R. Boarder. "Stimulation of phosphatidate synthesis in endothelial cells in response to P2-receptor activation. Evidence for phospholipase C and phospholipase D involvement, phosphatidate and diacylglycerol interconversion and the role of protein kinase C". Biochemical Journal 287, nr 1 (1.10.1992): 31–36. http://dx.doi.org/10.1042/bj2870031.

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To investigate the stimulation of phosphatidic acid formation in bovine aortic endothelial cells by P2-purinergic agonists, we labelled AG4762 cells with [32P]P1 and stimulated in the presence of butanol. Under these conditions phospholipase D generated [32P]phosphatidylbutanol, whereas the [32P]phosphatidic acid from phospholipase C and diacylglycerol kinase was unchanged. The action of various purinergic agonists on both [32P]phosphatidic acid and [32P]phosphatidylbutanol was consistent with the presence of a P2Y receptor. The stimulation of phospholipase D was dependent on extracellular Ca2+ and was mostly transient (completed within 3 min), whereas the initial stimulation of phospholipase C was independent of extracellular Ca2+, followed by a Ca(2+)-dependent phase. The agonist stimulation of phospholipase D was dependent on protein kinase C, as judged by its sensitivity to the relatively selective protein kinase C inhibitor Ro 31-8220. These results show that purinergic-receptor-mediated stimulation of phosphatidic acid has three phases: an initial Ca(2+)-independent stimulation of phospholipase C, an early but transient Ca(2+)- and protein kinase C-dependent stimulation of phospholipase D, and a sustained Ca(2+)-dependent stimulation of phospholipase C. Using propranolol to inhibit phosphatidate phosphohydrolase, we provide evidence that phosphatidic acid derived from purinergic-receptor-mediated stimulation of the phospholipase C/diacylglycerol kinase route can itself be converted back into diacylglycerol.

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47

Rice, K. L., P. G. Duane, G. Mielke, A. A. Sinha i D. E. Niewoehner. "Calcium ionophores injure alveolar epithelial cells: relation to phospholipase activity". American Journal of Physiology-Lung Cellular and Molecular Physiology 259, nr 6 (1.12.1990): L439—L450. http://dx.doi.org/10.1152/ajplung.1990.259.6.l439.

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Phospholipases and certain of their hydrolytic products are toxic to alveolar epithelial cells. Since many intracellular phospholipases are Ca2+ dependent, we postulated that elevating cytosolic Ca2+ with ionophores might cause epithelial injury via phospholipase activation. Isolated perfused hamster lungs exposed to an Ca2+ ionophore A23187 develop functional evidence of severe epithelial injury. Ultrastructural studies show widespread lysis of type I epithelial cells, with only minimal abnormalities in other lung cells, including the microvascular endothelium. Analysis of whole lung lipid extracts reveals a modest elevation in free arachidonic acid but no changes in other putative products of phospholipase activity. Parallel studies were performed in cultured cells of pulmonary origin. As measured by 51Cr release, A23187 causes substantial cytotoxicity in 3-day-old cultures of rat type II alveolar epithelial cells (RAEC) but not in cultured bovine pulmonary artery endothelial cells (BPAEC). RAEC prelabeled with [14C]stearic acid [( 14C]SA) and [3H]arachidonic acid [( 3H]AA) release radiolabeled free fatty acids (FFA) in response to A23187 in a dose- and time-dependent manner that parallels the cytotoxicity index. Analyses of putative phospholipase products in cells radiolabeled with [14C]SA and [3H]AA, with [14C]choline, or with [14C]ethanolamine suggest that liberation of radiolabeled FFA may be due to several phospholipases but with principal activity being exhibited by a phospholipase C having specificity toward phosphatidylcholine and phosphatidylethanolamine. Prelabeled BPAEC release only minimal quantities of FFA in response to A23187 under the same conditions. These studies demonstrate that elevations of intracytoplasmic Ca2+ are capable of severely and selectively damaging alveolar epithelial cells and that the injury is associated with activation of intracellular phospholipases. These findings may have implications in regard to the pathogenesis of acute lung injury in humans.

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Ortiz-Placín, Cándido, Alba Castillejo-Rufo, Matías Estarás i Antonio González. "Membrane Lipid Derivatives: Roles of Arachidonic Acid and Its Metabolites in Pancreatic Physiology and Pathophysiology". Molecules 28, nr 11 (24.05.2023): 4316. http://dx.doi.org/10.3390/molecules28114316.

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One of the most important constituents of the cell membrane is arachidonic acid. Lipids forming part of the cellular membrane can be metabolized in a variety of cellular types of the body by a family of enzymes termed phospholipases: phospholipase A2, phospholipase C and phospholipase D. Phospholipase A2 is considered the most important enzyme type for the release of arachidonic acid. The latter is subsequently subjected to metabolization via different enzymes. Three enzymatic pathways, involving the enzymes cyclooxygenase, lipoxygenase and cytochrome P450, transform the lipid derivative into several bioactive compounds. Arachidonic acid itself plays a role as an intracellular signaling molecule. Additionally, its derivatives play critical roles in cell physiology and, moreover, are involved in the development of disease. Its metabolites comprise, predominantly, prostaglandins, thromboxanes, leukotrienes and hydroxyeicosatetraenoic acids. Their involvement in cellular responses leading to inflammation and/or cancer development is subject to intense study. This manuscript reviews the findings on the involvement of the membrane lipid derivative arachidonic acid and its metabolites in the development of pancreatitis, diabetes and/or pancreatic cancer.

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Berggren, P. O., A. Hallberg, N. Welsh, P. Arkahammar, T. Nilsson i M. Welsh. "Transfection of insulin-producing cells with a transforming c-Ha-ras oncogene stimulates phospholipase C activity". Biochemical Journal 259, nr 3 (1.05.1989): 701–7. http://dx.doi.org/10.1042/bj2590701.

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Pancreatic islet beta-cells and insulin-producing RINm5F cells were electroporated in the presence of the c-Ha-ras oncogene, to assess the possible involvement of the encoded product in coupling extracellular receptors to phospholipase C. After two days the c-Ha-ras-transfected cells increased their expression of c-Ha-ras mRNA. These cells were also found to contain more [3H]InsP3, suggesting an increased basal (non-ligand-activated) phospholipase C activity. In addition, the transfected cells were unable to respond to ligand (bombesin) activation of phospholipase C. The ras-transfected insulin-producing cells showed enhanced phosphorylation of a 200 kDa substrate crossreacting with an antibody to an 80 kDa protein kinase C substrate. The phorbol ester 12-O-tetradecanoyl 13-acetate and bombesin also induced phosphorylation of the 200 kDa substrate. All of these changes occurred without changes in the rates of [3H]thymidine incorporation. The results suggest that the mutated c-Ha-ras oncogene directly or indirectly stimulates the basal phospholipase C activity of these cells.

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Wolf, R. A. "Cardiolipin-sensitive phospholipase C in subcellular fractions of rabbit myocardium". American Journal of Physiology-Cell Physiology 257, nr 5 (1.11.1989): C926—C935. http://dx.doi.org/10.1152/ajpcell.1989.257.5.c926.

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Phosphatidylinositol-specific phospholipase C was characterized in the soluble phase and in membrane fractions prepared from rabbit myocardium. Four subforms of soluble phospholipase C were identified and characterized. Activity of one subform was inhibited 80% when cardiolipin was present in substrate vesicles, whereas three subforms were stimulated 2- to 10-fold by cardiolipin. A cationic subform, molecular mass 67 kDa, was stimulated threefold when cardiolipin comprised 2% of the total phospholipid and fivefold when it comprised 12%. The major mechanism for the cardiolipin effect was a decrease in the apparent Michaelis constant (Km) of this subform for substrate. Competition experiments were consistent with binding of this subform to cardiolipin. Phospholipase C activity was present in mitochondrial, microsomal, and sarcolemmal membrane fractions that were essentially free of contamination by cytosol. Detection of membrane-associated phospholipase C was facilitated by cardiolipin. Thus rabbit myocardium contains multiple subforms of soluble phospholipase C that differ substantially in surface charge, molecular mass, and sensitivity to cardiolipin. Anionic phospholipids may be important determinants of intracellular distribution of phospholipase C in myocardial tissue.

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