The Experts below are selected from a list of 1284 Experts worldwide ranked by ideXlab platform
Priscilla L Yang - One of the best experts on this subject based on the ideXlab platform.
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hepatitis c virus ns3 4a protease regulates the lipid environment for rna replication by cleaving host enzyme 24 dehydrocholesterol reductase
Journal of Biological Chemistry, 2020Co-Authors: Lorillee Tallorin, Mary A Rodgers, Valerie A Villareal, Chihyun Hsia, Dominique J Burri, Marcphilipp Pfeil, Paula Montero Llopis, Brett D Lindenbach, Priscilla L YangAbstract:Many RNA viruses create specialized membranes for genome replication by manipulating host lipid metabolism and trafficking, but in most cases, we do not know the molecular mechanisms responsible or how specific lipids may impact the associated membrane and viral process. For example, hepatitis C virus (HCV) causes a specific, large-fold increase in the steady-state abundance of intracellular Desmosterol, an immediate precursor of cholesterol, resulting in increased fluidity of the membrane where HCV RNA replication occurs. Here, we establish the mechanism responsible for HCV's effect on intracellular Desmosterol, whereby the HCV NS3-4A protease controls activity of 24-dehydrocholesterol reductase (DHCR24), the enzyme that catalyzes conversion of Desmosterol to cholesterol. Our cumulative evidence for the proposed mechanism includes immunofluorescence microscopy experiments showing co-occurrence of DHCR24 and HCV NS3-4A protease; formation of an additional, faster-migrating DHCR24 species (DHCR24*) in cells harboring a HCV subgenomic replicon RNA or ectopically expressing NS3-4A; and biochemical evidence that NS3-4A cleaves DHCR24 to produce DHCR24* in vitro and in vivo. We further demonstrate that NS3-4A cleaves DHCR24 between residues Cys91 and Thr92 and show that this reduces the intracellular conversion of Desmosterol to cholesterol. Together, these studies demonstrate that NS3-4A directly cleaves DHCR24 and that this results in the enrichment of Desmosterol in the membranes where NS3-4A and DHCR24 co-occur. Overall, this suggests a model in which HCV directly regulates the lipid environment for RNA replication through direct effects on the host lipid metabolism.
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Desmosterol increases lipid bilayer fluidity during hepatitis c virus infection
ACS Infectious Diseases, 2016Co-Authors: Deirdre A. Costello, Valerie A Villareal, Priscilla L YangAbstract:Hepatitis C virus (HCV) uniquely affects Desmosterol homeostasis by increasing its intracellular abundance and affecting its localization. These effects are important for productive viral replication because the inhibition of Desmosterol synthesis has an antiviral effect that can be rescued by the addition of exogenous Desmosterol. Here, we use subgenomic replicons to show that Desmosterol has a major effect on the replication of HCV JFH1 RNA. Fluorescence recovery after photobleaching (FRAP) experiments performed with synthetic supported lipid bilayers demonstrate that the substitution of Desmosterol for cholesterol significantly increases the lipid bilayer fluidity, especially in the presence of saturated phospholipids and ceramides. We demonstrate using LC-MS that Desmosterol is abundant in the membranes upon which genome replication takes place and that supported lipid bilayers derived from these specialized membranes also exhibit significantly higher fluidity compared to that of negative control memb...
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Hepatitis C Virus Selectively Alters the Intracellular Localization of Desmosterol
2016Co-Authors: Valerie A. Villareal, Deirdre A. Costello, Xiaoliang Sunney Xie, Priscilla L YangAbstract:Hepatitis C virus (HCV) increases intracellular Desmosterol without affecting the steady-state abundance of other sterols, and the antiviral activity of inhibitors of Desmosterol synthesis is suppressed by the addition of exogenous Desmosterol. These observations suggest a model in which Desmosterol has a specific function, direct or indirect, in HCV replication and that HCV alters Desmosterol homeostasis to promote viral replication. Here, we use stimulated Raman scattering (SRS) microscopy in combination with isotopically labeled sterols to show that HCV causes Desmosterol to accumulate in lipid droplets that are closely associated with the viral NS5A protein and that are visually distinct from the broad distribution of Desmosterol in mock-infected cells and the more heterogeneous and disperse lipid droplets to which cholesterol traffics. Localization of Desmosterol in NS5A-associated lipid droplets suggests that Desmosterol may affect HCV replication via a direct mechanism. We anticipate that SRS microscopy and similar approaches can provide much needed tools to study the localization of specific lipid molecules in cellulo and in vivo
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lipid metabolite profiling identifies Desmosterol metabolism as a new antiviral target for hepatitis c virus
Journal of the American Chemical Society, 2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography-mass spectrometry (LC-MS) metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for anti-viral design.
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Lipid Metabolite Profiling Identifies Desmosterol Metabolism as a New Antiviral Target for Hepatitis C Virus
2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography–mass spectrometry metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady-state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for antiviral design
Yasmin Dias Guichot - One of the best experts on this subject based on the ideXlab platform.
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Protective Role of Plant Sterol and Stanol Esters in Liver Inflammation: Insights from Mice and Humans
2016Co-Authors: Jogchum Plat, Els De Smet, Anita C. E. Vreugdenhil, Maurice Konings, Tim Hendrikx, Veerle Bieghs, Mike L. J. Jeurissen, Sofie M. A. Walenbergh, Patrick J. Van Gorp, Yasmin Dias GuichotAbstract:The inflammatory component of non–alcoholic steatohepatitis (NASH) can lead to irreversible liver damage. Therefore there is an urgent need to identify novel interventions to combat hepatic inflammation. In mice, omitting cholesterol from the diet reduced hepatic inflammation. Considering the effects of plant sterol/stanol esters on cholesterol metabolism, we hypothesized that plant sterol/stanol esters reduces hepatic inflammation. Indeed, adding plant sterol/stanol esters to a high-fat-diet reduced hepatic inflammation as indicated by immunohistochemical stainings and gene expression for inflammatory markers. Finally, adding sterol/stanol esters lowered hepatic concentrations of cholesterol precursors lathosterol and Desmosterol in mice, which were highly elevated in the HFD group similarly as observed in severely obese patients with NASH. In vitro, in isolated LPS stimulated bone marrow derived macrophages Desmosterol activated cholesterol efflux whereas sitostanol reduced inflammation. This highly interesting observation that plant sterol/stanol ester consumption leads to complete inhibition of HFD-induced liver inflammation opens new venues in the treatment an
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Protective role of plant sterol and stanol esters in liver inflammation: insights from mice and humans.
PloS one, 2014Co-Authors: Jogchum Plat, Els De Smet, Anita C. E. Vreugdenhil, Maurice Konings, Tim Hendrikx, Veerle Bieghs, Mike L. J. Jeurissen, Sofie M. A. Walenbergh, Patrick J. Van Gorp, Yasmin Dias GuichotAbstract:The inflammatory component of non-alcoholic steatohepatitis (NASH) can lead to irreversible liver damage. Therefore there is an urgent need to identify novel interventions to combat hepatic inflammation. In mice, omitting cholesterol from the diet reduced hepatic inflammation. Considering the effects of plant sterol/stanol esters on cholesterol metabolism, we hypothesized that plant sterol/stanol esters reduces hepatic inflammation. Indeed, adding plant sterol/stanol esters to a high-fat-diet reduced hepatic inflammation as indicated by immunohistochemical stainings and gene expression for inflammatory markers. Finally, adding sterol/stanol esters lowered hepatic concentrations of cholesterol precursors lathosterol and Desmosterol in mice, which were highly elevated in the HFD group similarly as observed in severely obese patients with NASH. In vitro, in isolated LPS stimulated bone marrow derived macrophages Desmosterol activated cholesterol efflux whereas sitostanol reduced inflammation. This highly interesting observation that plant sterol/stanol ester consumption leads to complete inhibition of HFD-induced liver inflammation opens new venues in the treatment and prevention of hepatic inflammation.
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Schematic representation of direct effects of sitostanol vs Desmosterol.
2014Co-Authors: Jogchum Plat, Anita C. E. Vreugdenhil, Tim Hendrikx, Veerle Bieghs, Mike L. J. Jeurissen, Sofie M. A. Walenbergh, Patrick J. Van Gorp, Yasmin Dias GuichotAbstract:Schematic representation of direct effects of sitostanol vs Desmosterol.
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Effect of plant stanols on macrophages in vitro.
2014Co-Authors: Jogchum Plat, Els De Smet, Anita C. E. Vreugdenhil, Maurice Konings, Tim Hendrikx, Veerle Bieghs, Mike L. J. Jeurissen, Sofie M. A. Walenbergh, Patrick J. Van Gorp, Yasmin Dias GuichotAbstract:Changes in Tnf-α concentrations in supernatant and LXR target gene expression of bone marrow derived macrophages after incubation with sitostanol (0.6 and 1.2 µm) or Desmosterol (0.25, 0.5 and 1.0 µm) and 4 h LPS stimulation. (A) Tnf-α concentrations, (B) LXRα mRNA, (C) Abca1 mRNA, and (D) Abcg1 mRNA expression after sitostanol exposure, (E) Tnf-α mRNA, (F) LXRα mRNA, (G) Abca1 mRNA, and (H) Abcg1 mRNA expression after Desmosterol exposure. Data were set relative to cells incubated with cyclodextrin (carrier control). *P
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Hepatic non-cholesterol sterol concentrations.
2014Co-Authors: Jogchum Plat, Anita C. E. Vreugdenhil, Tim Hendrikx, Veerle Bieghs, Mike L. J. Jeurissen, Sofie M. A. Walenbergh, Patrick J. Van Gorp, Yasmin Dias GuichotAbstract:Hepatic concentrations of (A) campesterol, (B) sitosterol, (C) campestanol and (D) sitostanol were measured. To analyze endogenous cholesterol synthesis, hepatic (E) lathosterol and (F) Desmosterol were measured. All values are shown as absolute concentrations (ng/mg tissue). n = 10 per group. *P
Valerie A Villareal - One of the best experts on this subject based on the ideXlab platform.
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hepatitis c virus ns3 4a protease regulates the lipid environment for rna replication by cleaving host enzyme 24 dehydrocholesterol reductase
Journal of Biological Chemistry, 2020Co-Authors: Lorillee Tallorin, Mary A Rodgers, Valerie A Villareal, Chihyun Hsia, Dominique J Burri, Marcphilipp Pfeil, Paula Montero Llopis, Brett D Lindenbach, Priscilla L YangAbstract:Many RNA viruses create specialized membranes for genome replication by manipulating host lipid metabolism and trafficking, but in most cases, we do not know the molecular mechanisms responsible or how specific lipids may impact the associated membrane and viral process. For example, hepatitis C virus (HCV) causes a specific, large-fold increase in the steady-state abundance of intracellular Desmosterol, an immediate precursor of cholesterol, resulting in increased fluidity of the membrane where HCV RNA replication occurs. Here, we establish the mechanism responsible for HCV's effect on intracellular Desmosterol, whereby the HCV NS3-4A protease controls activity of 24-dehydrocholesterol reductase (DHCR24), the enzyme that catalyzes conversion of Desmosterol to cholesterol. Our cumulative evidence for the proposed mechanism includes immunofluorescence microscopy experiments showing co-occurrence of DHCR24 and HCV NS3-4A protease; formation of an additional, faster-migrating DHCR24 species (DHCR24*) in cells harboring a HCV subgenomic replicon RNA or ectopically expressing NS3-4A; and biochemical evidence that NS3-4A cleaves DHCR24 to produce DHCR24* in vitro and in vivo. We further demonstrate that NS3-4A cleaves DHCR24 between residues Cys91 and Thr92 and show that this reduces the intracellular conversion of Desmosterol to cholesterol. Together, these studies demonstrate that NS3-4A directly cleaves DHCR24 and that this results in the enrichment of Desmosterol in the membranes where NS3-4A and DHCR24 co-occur. Overall, this suggests a model in which HCV directly regulates the lipid environment for RNA replication through direct effects on the host lipid metabolism.
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Desmosterol increases lipid bilayer fluidity during hepatitis c virus infection
ACS Infectious Diseases, 2016Co-Authors: Deirdre A. Costello, Valerie A Villareal, Priscilla L YangAbstract:Hepatitis C virus (HCV) uniquely affects Desmosterol homeostasis by increasing its intracellular abundance and affecting its localization. These effects are important for productive viral replication because the inhibition of Desmosterol synthesis has an antiviral effect that can be rescued by the addition of exogenous Desmosterol. Here, we use subgenomic replicons to show that Desmosterol has a major effect on the replication of HCV JFH1 RNA. Fluorescence recovery after photobleaching (FRAP) experiments performed with synthetic supported lipid bilayers demonstrate that the substitution of Desmosterol for cholesterol significantly increases the lipid bilayer fluidity, especially in the presence of saturated phospholipids and ceramides. We demonstrate using LC-MS that Desmosterol is abundant in the membranes upon which genome replication takes place and that supported lipid bilayers derived from these specialized membranes also exhibit significantly higher fluidity compared to that of negative control memb...
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lipid metabolite profiling identifies Desmosterol metabolism as a new antiviral target for hepatitis c virus
Journal of the American Chemical Society, 2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography-mass spectrometry (LC-MS) metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for anti-viral design.
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Lipid Metabolite Profiling Identifies Desmosterol Metabolism as a New Antiviral Target for Hepatitis C Virus
2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography–mass spectrometry metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady-state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for antiviral design
Mary A Rodgers - One of the best experts on this subject based on the ideXlab platform.
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hepatitis c virus ns3 4a protease regulates the lipid environment for rna replication by cleaving host enzyme 24 dehydrocholesterol reductase
Journal of Biological Chemistry, 2020Co-Authors: Lorillee Tallorin, Mary A Rodgers, Valerie A Villareal, Chihyun Hsia, Dominique J Burri, Marcphilipp Pfeil, Paula Montero Llopis, Brett D Lindenbach, Priscilla L YangAbstract:Many RNA viruses create specialized membranes for genome replication by manipulating host lipid metabolism and trafficking, but in most cases, we do not know the molecular mechanisms responsible or how specific lipids may impact the associated membrane and viral process. For example, hepatitis C virus (HCV) causes a specific, large-fold increase in the steady-state abundance of intracellular Desmosterol, an immediate precursor of cholesterol, resulting in increased fluidity of the membrane where HCV RNA replication occurs. Here, we establish the mechanism responsible for HCV's effect on intracellular Desmosterol, whereby the HCV NS3-4A protease controls activity of 24-dehydrocholesterol reductase (DHCR24), the enzyme that catalyzes conversion of Desmosterol to cholesterol. Our cumulative evidence for the proposed mechanism includes immunofluorescence microscopy experiments showing co-occurrence of DHCR24 and HCV NS3-4A protease; formation of an additional, faster-migrating DHCR24 species (DHCR24*) in cells harboring a HCV subgenomic replicon RNA or ectopically expressing NS3-4A; and biochemical evidence that NS3-4A cleaves DHCR24 to produce DHCR24* in vitro and in vivo. We further demonstrate that NS3-4A cleaves DHCR24 between residues Cys91 and Thr92 and show that this reduces the intracellular conversion of Desmosterol to cholesterol. Together, these studies demonstrate that NS3-4A directly cleaves DHCR24 and that this results in the enrichment of Desmosterol in the membranes where NS3-4A and DHCR24 co-occur. Overall, this suggests a model in which HCV directly regulates the lipid environment for RNA replication through direct effects on the host lipid metabolism.
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lipid metabolite profiling identifies Desmosterol metabolism as a new antiviral target for hepatitis c virus
Journal of the American Chemical Society, 2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography-mass spectrometry (LC-MS) metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for anti-viral design.
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Lipid Metabolite Profiling Identifies Desmosterol Metabolism as a New Antiviral Target for Hepatitis C Virus
2012Co-Authors: Mary A Rodgers, Valerie A Villareal, Esperance A Schaefer, Lee F Peng, Kathleen E Corey, Raymond T Chung, Priscilla L YangAbstract:Hepatitis C virus (HCV) infection has been clinically associated with serum lipid abnormalities, yet our understanding of the effects of HCV on host lipid metabolism and conversely the function of individual lipids in HCV replication remains incomplete. Using liquid chromatography–mass spectrometry metabolite profiling of the HCV JFH1 cell culture infection model, we identified a significant steady-state accumulation of Desmosterol, an immediate precursor to cholesterol. Pharmacological inhibition or RNAi-mediated depletion of DHCR7 significantly reduced steady-state HCV protein expression and viral genomic RNA. Moreover, this effect was reversed when cultures were supplemented with exogenous Desmosterol. Together, these observations suggest an intimate connection between HCV replication and Desmosterol homeostasis and that the enzymes responsible for synthesis of Desmosterol may be novel targets for antiviral design
Miguel A Lasuncion - One of the best experts on this subject based on the ideXlab platform.
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inhibition of cholesterol biosynthesis by δ22 unsaturated phytosterols via competitive inhibition of sterol δ24 reductase in mammalian cells
Biochemical Journal, 2002Co-Authors: C Fernandez, Yajaira Suarez, Antonio J Ferruelo, Diego Gomezcoronado, Miguel A LasuncionAbstract:Dietary phytosterols are cholesterol-lowering agents that interfere with the intestinal absorption of cholesterol. In the present study, we have studied their effects on cholesterol biosynthesis in human cells, particularly in the sterol-conversion pathway. For this, both Caco-2 (intestinal mucosa) and HL-60 (promyelocytic) human cell lines were incubated with [(14)C]acetate, and the incorporation of radioactivity into sterols was determined using HPLC and radioactivity detection online. Sterols containing a double bond at C-22 in the side chain (stigmasterol, brassicasterol and ergosterol) dramatically inhibited the activity of sterol Delta(24)-reductase, as indicated by the decrease in radioactivity incorporation into cholesterol and the accumulation of its precursors (mainly Desmosterol). Phytosterols with the saturated side chain (beta-sitosterol and campesterol) were inactive in this regard. The inhibition of sterol (24)-reductase was confirmed in rat liver microsomes by using (14)C-labelled Desmosterol as the substrate. The (22)-unsaturated phytosterols acted as competitive inhibitors of sterol (24)-reductase, with K(i) values (41.1, 42.7 and 36.8 microM for stigmasterol, brassicasterol and ergosterol respectively) similar to the estimated K(m) for Desmosterol (26.3 microM). The sterol 5,22-cholestedien-3beta-ol, an unusual Desmosterol isomer that lacks the alkyl groups characteristic of phytosterols, acted as a much stronger inhibitor of (24)-reductase (K(i)=3.34 microM). The usually low intracellular concentrations of the physiological substrates of (24)-reductase explains the strong inhibition of cholesterol biosynthesis that these compounds exert in cells. Given that inhibition of sterol (24)-reductase was achieved at physiologically relevant concentrations, it may represent an additional mechanism for the cholesterol-lowering action of phytosterols, and opens up the possibility of using certain (22)-unsaturated sterols as effective hypocholesterolaemic agents.