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Phosphatidylcholine and the CDP-choline cycle. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:523-32. [PMID: 23010477 DOI: 10.1016/j.bbalip.2012.09.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 09/16/2012] [Indexed: 11/20/2022]
Abstract
The CDP-choline pathway of phosphatidylcholine (PtdCho) biosynthesis was first described more than 50 years ago. Investigation of the CDP-choline pathway in yeast provides a basis for understanding the CDP-choline pathway in mammals. PtdCho is considered as an intermediate in a cycle of synthesis and degradation, and the activity of a CDP-choline cycle is linked to subcellular membrane lipid movement. The components of the mammalian CDP-choline pathway include choline transport, choline kinase, phosphocholine cytidylyltransferase, and choline phosphotransferase activities. The protein isoforms and biochemical mechanisms of regulation of the pathway enzymes are related to their cell- and tissue-specific functions. Regulated PtdCho turnover mediated by phospholipases or neuropathy target esterase participates in the mammalian CDP-choline cycle. Knockout mouse models define the biological functions of the CDP-choline cycle in mammalian cells and tissues. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Cytochalasin D enhances the accumulation of a protease-resistant form of prion protein in ScN2a cells: involvement of PI3 kinase/Akt signalling pathway. Cell Biol Int 2012; 36:1223-31. [PMID: 22985412 DOI: 10.1042/cbi20120329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The conversion of a host-encoded PrPsen (protease-sensitive cellular prion protein) into a PrPres (protease-resistant pathogenic form) is a key process in the pathogenesis of prion diseases, but the intracellular mechanisms underlying PrPres amplification in prion-infected cells remain elusive. To assess the role of cytoskeletal proteins in the regulation of PrPres amplification, the effects of cytoskeletal disruptors on PrPres accumulation in ScN2a cells that were persistently infected with the scrapie Chandler strain have been examined. Actin microfilament disruption with cytochalasin D enhanced PrPres accumulation in ScN2a cells. In contrast, the microtubule-disrupting agents, colchicine, nocodazole and paclitaxel, had no effect on PrPres accumulation. In addition, a PI3K (phosphoinositide 3-kinase) inhibitor, wortmannin and an Akt kinase inhibitor prevented the cytochalasin D-induced enhancement of PrPres accumulation. Cytochalasin D-induced extension of neurite-like processes might correlate with enhanced accumulation of PrPres. The results suggest that the actin cytoskeleton and PI3K/Akt pathway are involved in the regulation of PrPres accumulation in prion-infected cells.
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Sinner DI, Kim GJ, Henderson GC, Igal RA. StearoylCoA desaturase-5: a novel regulator of neuronal cell proliferation and differentiation. PLoS One 2012; 7:e39787. [PMID: 22745828 PMCID: PMC3382174 DOI: 10.1371/journal.pone.0039787] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/30/2012] [Indexed: 12/15/2022] Open
Abstract
Recent studies have demonstrated that human stearoylCoA desaturase-1 (SCD1), a Δ9-desaturase that converts saturated fatty acids (SFA) into monounsaturated fatty acids, controls the rate of lipogenesis, cell proliferation and tumorigenic capacity in cancer cells. However, the biological function of stearoylCoA desaturase-5 (SCD5), a second isoform of human SCD that is highly expressed in brain, as well as its potential role in human disease, remains unknown. In this study we report that the constitutive overexpression of human SCD5 in mouse Neuro2a cells, a widely used cell model of neuronal growth and differentiation, displayed a greater n-7 MUFA-to-SFA ratio in cell lipids compared to empty-vector transfected cells (controls). De novo synthesis of phosphatidylcholine and cholesterolesters was increased whereas phosphatidylethanolamine and triacylglycerol formation was reduced in SCD5-expressing cells with respect to their controls, suggesting a differential use of SCD5 products for lipogenic reactions. We also observed that SCD5 expression markedly accelerated the rate of cell proliferation and suppressed the induction of neurite outgrowth, a typical marker of neuronal differentiation, by retinoic acid indicating that the desaturase plays a key role in the mechanisms of cell division and differentiation. Critical signal transduction pathways that are known to modulate these processes, such epidermal growth factor receptor (EGFR)Akt/ERK and Wnt, were affected by SCD5 expression. Epidermal growth factor-induced phosphorylation of EGFR, Akt and ERK was markedly blunted in SCD5-expressing cells. Furthermore, the activity of canonical Wnt was reduced whereas the non-canonical Wnt was increased by the presence of SCD5 activity. Finally, SCD5 expression increased the secretion of recombinant Wnt5a, a non-canonical Wnt, whereas it reduced the cellular and secreted levels of canonical Wnt7b. Our data suggest that, by a coordinated modulation of key lipogenic pathways and transduction signaling cascades, SCD5 participates in the regulation of neuronal cell growth and differentiation.
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Affiliation(s)
- Debora I. Sinner
- Section of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children's Medical Center, Cincinnati, Ohio, United States of America
| | - Gretchun J. Kim
- Department of Nutritional Sciences and Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - Gregory C. Henderson
- Department of Exercise Science, and Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
| | - R. Ariel Igal
- Department of Nutritional Sciences and Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, United States of America
- * E-mail:
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The amphipathic helix of an enzyme that regulates phosphatidylcholine synthesis remodels membranes into highly curved nanotubules. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:1173-86. [DOI: 10.1016/j.bbamem.2012.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 11/20/2022]
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Batra V, Kislay B, Devasagayam TPA. Interaction between total body gamma-irradiation and choline deficiency triggers immediate modulation of choline and choline-containing moieties. Int J Radiat Biol 2011; 87:1196-207. [PMID: 21923302 DOI: 10.3109/09553002.2011.624153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The objective of this study was to examine the effect of 60Co-gamma (γ) radiation on acute phase modulation, if any, of choline and choline-containing moieties in choline-deficient subjects. Corresponding results could provide information that might be useful in the management of adverse effects of γ-radiation. MATERIALS AND METHODS Male Swiss mice maintained on a choline-sufficient diet (CSD) and choline-free diet (CFD) based on AIN-93M formula, were subjected to whole body γ-irradiation (2-6 Gy). Liver, serum and brain samples from each group were then tested for: (i) Alterations in choline and choline-containing moieties such as phosphatidylcholine (PC) and sphingomyeline (SM); and (ii) modulation of choline profile modulating enzymes such as phospholipase D (PLD) and total sphingomyelinase (t-SMase). Liver and brain samples were also subjected to histo-pathological examinations. RESULTS No significant changes were observed in folate, choline, choline-containing moieties and choline-modulating enzymes in choline-sufficient mice. In contrast, interaction between cytotoxic effects of γ-radiation and choline deficiency modulated choline and choline-containing moieties. Feeding CFD reduced hepatic concentrations of choline, PC and SM whereas PLD and t-SMase activities were significantly raised. The decrease in liver choline and choline-containing moieties was accompanied by an increase in blood choline concentration. Despite choline deficiency, the level of choline and acetylcholine synthesizing enzyme choline acetyltransfease (ChAT) significantly increased in the brain. CONCLUSIONS We propose that choline deprivation and γ-radiation interact to modulate choline reserves of hepatic tissue, which might release choline to blood. Our studies also clearly showed that interaction between choline deficiency and γ-radiation might substantially enhance liver adipogenesis.
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Affiliation(s)
- Vipen Batra
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India.
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Strakova J, Demizieux L, Campenot RB, Vance DE, Vance JE. Involvement of CTP:phosphocholine cytidylyltransferase-β2 in axonal phosphatidylcholine synthesis and branching of neurons. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:617-25. [DOI: 10.1016/j.bbalip.2011.06.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 06/06/2011] [Accepted: 06/15/2011] [Indexed: 10/18/2022]
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Paoletti L, Elena C, Domizi P, Banchio C. Role of Phosphatidylcholine during Neuronal differentiation. IUBMB Life 2011; 63:714-20. [DOI: 10.1002/iub.521] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 05/19/2011] [Indexed: 12/15/2022]
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Bartoccini E, Marini F, Damaskopoulou E, Lazzarini R, Cataldi S, Cascianelli G, Gil Garcia M, Albi E. Nuclear lipid microdomains regulate nuclear vitamin D3 uptake and influence embryonic hippocampal cell differentiation. Mol Biol Cell 2011; 22:3022-31. [PMID: 21737687 PMCID: PMC3164451 DOI: 10.1091/mbc.e11-03-0196] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Despite recent advances in the understanding of the role of 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) in the CNS, the mechanism of action remains obscure. We demonstrate that some 1,25-(OH)(2)D(3) receptor (VDR) is localized in the cell nucleus in specialized microdomains enriched in sphingomyelin and cholesterol; the integrity of these microdomains is necessary for embryonic hippocampal cell differentiation. Sphingomyelinase (SMase) treatment reduces both VDR and labeled 1,25-(OH)(2)D(3) content in nuclear microdomains. We have previously shown that HN9.10e embryonic hippocampal cells differentiate when incubated with 100 nM 1,25-(OH)(2)D(3) in the presence of 10% fetal calf serum, while serum deprivation induces cell death. In this study, we have investigated whether conditions that alter lipid content of nuclear microdomains modify 1,25-(OH)(2)D(3)-induced differentiation. Serum deprivation activates SMase and modifies the composition of nuclear microdomains, which lose the 1,25-(OH)(2) vitamin D(3) receptor. The incubation of serum-deprived cells with 100 nM 1,25-(OH)(2)D(3) prevents differentiation. However, treatment with 400 nM 1,25-(OH)(2)D(3) during serum withdrawal increases the lipid content of the nuclear microdomains, allows the interaction of 1,25-(OH)(2)D(3) with its receptor, and results in differentiation. These results suggest the presence of VDR in nuclear microdomains is necessary for 1,25-(OH)(2)D(3)-induced differentiation in embryonic hippocampal cells.
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Affiliation(s)
- Elisa Bartoccini
- Physiopathology Section, Department of Clinical and Experimental Medicine, University School of Medicine, University of Perugia, Perugia, Italy.
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Hermansson M, Hokynar K, Somerharju P. Mechanisms of glycerophospholipid homeostasis in mammalian cells. Prog Lipid Res 2011; 50:240-57. [DOI: 10.1016/j.plipres.2011.02.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 02/21/2011] [Accepted: 02/25/2011] [Indexed: 01/09/2023]
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Moreno-Baylach MJ, Puttonen KA, Tenorio-Laranga J, Venäläinen JI, Storvik M, Forsberg MM, García-Horsman JA. Prolyl endopeptidase is involved in cellular signalling in human neuroblastoma SH-SY5Y cells. Neurosignals 2011; 19:97-109. [PMID: 21487212 DOI: 10.1159/000326342] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 02/22/2011] [Indexed: 11/19/2022] Open
Abstract
Prolyl endopeptidase (PREP), probably acting through the inositol cycle, has been implicated in memory and learning. However, the physiological role of PREP is unknown. It has been shown that PREP expression, regulated in cerebellar granule cells, has probably a role in cell proliferation and differentiation. Here, we report the levels and subcellular distribution of PREP in human neuroblastoma SH-SY5Y cells in proliferating conditions and under differentiation induced by retinoic acid (RA). We analysed the levels of cell signalling intermediates, growth behavior and gene expression, and differentiation morphology changes, upon PREP inhibition. After induction of differentiation, PREP activity was found decreased in the nucleus but increased to high levels in the cytoplasm, due in part to increased PREP transcription. The levels of inositol (1,4,5)-trisphosphate revealed no correlation with PREP activity, but phosphorylated extracellular signal-regulated kinases 1 and 2 were decreased by PREP inhibition during early stages of differentiation. Morphological evaluation indicated that PREP inhibition retarded the onset of differentiation. PREP activity regulated gene expression of protein synthesis machinery, intracellular transport and kinase complexes. We conclude that PREP is a regulatory target and a regulatory element in cell signalling. This is the first report of a direct influence of a cell signalling molecule, RA, on PREP expression.
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Brownrigg TD, Theisen CS, Fibuch EE, Seidler NW. Carnosine protects against the neurotoxic effects of a serotonin-derived melanoid. Neurochem Res 2010; 36:467-75. [PMID: 21153702 DOI: 10.1007/s11064-010-0365-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2010] [Indexed: 11/26/2022]
Abstract
Anesthesia-related postoperative cognitive dysfunction (POCD) leads to morbidity in the elderly. Lipid peroxidative byproducts (i.e. acrolein) accumulate in aging and may play a role. Sevoflurane, an inhaled anesthetic, sequesters acrolein and enhances the formation of a serotonin-derived melanoid (SDM). SDM may be a biologically relevant polymeric melanoid that we previously showed exhibits redox activity and disrupts lipid bilayers. In this study, we examined the toxicity of SDM in cell culture and looked at protection using L-carnosine. SDM's toxic effects were tested on neuronal-like SH-SY5Y cells, causing an exponential decrease in viability, while human dermal fibroblasts were completely resistant to the toxic effects. SDM brought about morphological changes to differentiated SH-SY5Y cells, particularly to neuronal processes. Co- but not pre-treatment with L-carnosine protected differentiated SH-SY5Y cells exposed to SDM. Our mechanism suggests focal sevoflurane-induced sequestration of age-related acrolein leading to SDM synthesis and neuronal impairment, which is prevented by L-carnosine.
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Affiliation(s)
- Tanner D Brownrigg
- Department of Anesthesiology, University of Missouri-Kansas City School of Medicine, 4401 Wornall Road, Kansas City, MO 64111, USA
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