The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Ziqiang Luo - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of Pulmonary Surfactants Synthesis during N‐Methyl‐d‐Aspartate‐Induced Lung Injury
Basic & clinical pharmacology & toxicology, 2010Co-Authors: Li Shen, Hua She, Shaojie Yue, Ziqiang LuoAbstract:N-methyl-D-aspartate (NMDA) receptors are ionotropic glutamate receptors widely distributed in the central nervous system, and have been extensively investigated for their roles in embryonic development, synaptic plasticity and neuroexcitoxicity. Their functions in the peripheral nervous system and non-neural tissues have caught much attention recently. Over-activation of NMDA receptors induces excitotoxic lung injury. But the endogenous cell types in the lungs that express NMDA receptors remains elusive and the molecular mechanism underlies NMDA-induced lung injury has not been fully characterized. In this work, we reported that functional NMDA receptors were expressed in alveolar type II cells in the lungs. Over-activation of these receptors led to down-regulation of pulmonary surfactants synthesis. We further demonstrated that decreased cellular Choline-Phosphate Cytidylyltransferase alpha expression induced by NMDA treatment accounted for the decreased pulmonary surfactants synthesis. Our results provided important clues for treatment of glutamate lung injury by modulating pulmonary surfactants system.
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Role of c-fos gene in vasoactive intestinal peptide promoted synthesis of pulmonary surfactant phospholipids.
Regulatory peptides, 2007Co-Authors: Hua She, Shaojie Yue, Cha-xiang Guan, Xiaoqun Qin, Huijun Liu, Ziqiang LuoAbstract:Abstract We previously reported that vasoactive intestinal peptide (VIP) promoted synthesis of phosphatidylCholine (PC) in alveolar type II (ATII) cells. But the intracellular mechanism for this effect was unknown. In this work, we investigated the intracellular signal transduction pathway for VIP promoted synthesis of PC, the major lipid component of pulmonary surfactant (PS), by using an antagonist of VIP receptors, inhibitor of protein kinase C (PKC) and antisense oligonucleotides (AS-ODN) for c- fos oncogene. Our results showed that: ① [D-P-Cl-Phe(6)-Leu(17)]-VIP (10 − 6 mol/l), an antagonist of VIP receptors, could decrease the quantity of [ 3 H] Choline incorporation, microsomal Choline-Phosphate Cytidylyltransferase (CCT) mRNA expression and CCT activity induced by VIP (10 − 8 mol/l) in cultured lung explants to the control levels; ② VIP (10 − 8 mol/l) upregulated c-Fos protein expression in ATII cells. AS-ODN for c- fos oncogene (9 × 10 − 6 mol/l) could block the elevation of [ 3 H] Choline incorporation, microsomal CCT mRNA expression and CCT activity induced by VIP in cultured lung explants and in ATII cells; ③ H7 (10 − 5 mol/l), a PKC inhibitor could also reduce VIP induced [ 3 H] Choline incorporation, microsomal CCT mRNA expression and CCT activity in cultured lung explants and in ATII cells. These results demonstrated that VIP receptors, PKC and c-Fos protein played important roles in the signaling pathway through which VIP promoted the synthesis of PC.
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Effect of Vasoactive Intestinal Peptide on Pulmonary Surfactants Phospholipid Synthesis in Lung Explants
Acta pharmacologica Sinica, 2004Co-Authors: Ziqiang Luo, Fu-wen Zhou, Dan Dan Feng, Cha-xiang Guan, Chang Qing Zhang, Xiu Hong SunAbstract:AIM: To investigate the effect of vasoactive intestinal peptide (VIP) on pulmonary surfactants (PS) phospholipid synthesis in cultured lung explants. METHODS: Lung explants were cultured with serum-free medium, [methyl-(superscript 3)H]Choline incorporation, total phospholipid, phosphatidylCholine, activity of Choline-Phosphate Cytidylyltransferase (CCT) and CCTα mRNA level in lung explants were determined. RESULTS: (1) VIP (l0^(-10)-10^(-7)mo1/L) for 16 h promoted [methyl-(superscript 3)H]Choline incorporation in dose dependence and VIP (10^(-8) mol/L) for 2 h-16 h promoted [methyl-(superscript 3)H]Choline incorporation in time dependence. (2) VIP (10^(-8) mol/L) enhanced the contents of total phospholipids and phosphatidylCholine in lung explants. (3) VIP (10^(-10)-10^(-7) mol/L) elevated microsomal CCT activity of lung explants in dose dependence. (4) VIP (10^(-8) mol/L) increased expression of CCTα mRNA in lung explants and alveolar type Ⅱ cells (ATⅡ). (5) [D-P-Cl-Phe(6)-Leu(17)]-VIP (10^(-6) mol/L), a VIP receptors antagonist, abolished the increase of [(superscript 3)H] Choline incorporation, microsomal CCT activity and CCTα mRNA level induced by VIP (10^(-8) mol/L) in lung explants. CONCLUSION: VIP could enhance synthesis of phosphatidylCholine, the major component of pulmonary surfactants by enhancing microsomal CCT activity and CCTα mRNA level via VIP receptormediated pathway.
Kyun-hwan Kim - One of the best experts on this subject based on the ideXlab platform.
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PhosphatidylCholine Alteration Identified Using MALDI Imaging MS in HBV-Infected Mouse Livers and Virus-Mediated Regeneration Defects
2016Co-Authors: Eun-sook Park, Jeong Hwa Lee, Ji Hye Hong, Yong Kwang Park, Joon Won Lee, Won-jae Lee, Jae Won Lee, Kwang Pyo Kim, Kyun-hwan KimAbstract:In this study, we investigated whether hepatitis B virus (HBV) causes the alteration of lipid metabolism and composition during acute infection and liver regeneration in a mouse model. The liver controls lipid biogenesis and bile acid homeostasis. Infection of HBV causes various liver diseases and impairs liver regeneration. As there are very few reports available in the literature on lipid alterations by HBV infection or HBV-mediated liver injury, we have analyzed phospholipids that have important roles in liver regeneration by using matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS) in the livers of HBV model mice. As a result, we identified different phosphatidylCholines (PCs) showing significant changes in their composition as well as cationized ion adduct formation in HBV-infected mouse livers which are associated with virus-mediated regeneration defects. To find the factor of altered PCs, the expression kinetics of enzymes was also examined that regulate PC biosynthesis during liver regeneration. It is noteworthy that the expression of Choline-Phosphate Cytidylyltransferase A (PCYT1A) was significantly delayed in wild type HBV-expressing livers. Moreover, the amount of hepatic total PC was also significantly decreased in wt HBV-expressing mice. These results suggest that infectio
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PhosphatidylCholine Alteration Identified Using MALDI Imaging MS in HBV-Infected Mouse Livers and Virus-Mediated Regeneration Defects
PloS one, 2014Co-Authors: Eun-sook Park, Jeong Hwa Lee, Ji Hye Hong, Yong Kwang Park, Joon Won Lee, Won-jae Lee, Jae Won Lee, Kwang Pyo Kim, Kyun-hwan KimAbstract:In this study, we investigated whether hepatitis B virus (HBV) causes the alteration of lipid metabolism and composition during acute infection and liver regeneration in a mouse model. The liver controls lipid biogenesis and bile acid homeostasis. Infection of HBV causes various liver diseases and impairs liver regeneration. As there are very few reports available in the literature on lipid alterations by HBV infection or HBV-mediated liver injury, we have analyzed phospholipids that have important roles in liver regeneration by using matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS) in the livers of HBV model mice. As a result, we identified different phosphatidylCholines (PCs) showing significant changes in their composition as well as cationized ion adduct formation in HBV-infected mouse livers which are associated with virus-mediated regeneration defects. To find the factor of altered PCs, the expression kinetics of enzymes was also examined that regulate PC biosynthesis during liver regeneration. It is noteworthy that the expression of Choline-Phosphate Cytidylyltransferase A (PCYT1A) was significantly delayed in wild type HBV-expressing livers. Moreover, the amount of hepatic total PC was also significantly decreased in wt HBV-expressing mice. These results suggest that infection of HBV alters the composition of PCs which may involve in HBV-mediated regeneration defects and liver disease.
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Kinetic analysis of phosphatidylCholines (PCs) synthesis-related genes and measurement of total PCs level in regenerating liver tissues after partial hepatectomy.
2014Co-Authors: Eun-sook Park, Jeong Hwa Lee, Ji Hye Hong, Yong Kwang Park, Joon Won Lee, Won-jae Lee, Jae Won Lee, Kwang Pyo Kim, Kyun-hwan KimAbstract:(A) The schematic pathway of PC biosynthesis. PCYT1A, Choline-Phosphate Cytidylyltransferase A; PE, phosphatidylethanolamine; PMME, triolein-phosphatidyl-N-monomethyl ethanolamine; PDME, triolein-phosphatidyl-N,N-dimethyl ethanolamine; PEMT, phosphatidylethanolamine N-methyltransferase. (B–C) Kinetic analysis of Pcyt1a and Pemt expression in liver tissues after partial hepatectomy. At indicated time intervals after partial hepatectomy, the mRNA expression of indicated genes was analyzed using semi-quantitative RT-PCR (B) and real-time PCR (C), and Western blot analysis (D). (E) Quantification of hepatic PCs level after partial hepatectomy. Data represent the mean ±S.D. and are representative of three independent experiments. **, P
Seamus A. Rooney - One of the best experts on this subject based on the ideXlab platform.
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Enhanced fatty acid biosynthesis and normal surfactant secretion in hypertrophic rat type II cells.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1991Co-Authors: J. Rami, S. M. Sasic, Seamus A. RooneyAbstract:Silica instillation causes lung surfactant accumulation as well as hyperplasia and hypertrophy of type II pneumocytes. Two populations of type II cells can be isolated from silica-treated rats: type IIA, which are similar to type II cells from normal animals and type IIB, which are larger and have a higher rate of phosphatidylCholine biosynthesis. We have compared fatty acid biosynthesis and phosphatidylCholine secretion in types IIA and IIB cells and in type II cells from control rats. The cells were isolated by elastase digestion and panning on immunoglobulin G-coated plates and fractionated into types IIA and IIB by centrifugal elutriation. Type IIB cells contained more phospholipid and had an enhanced rate of [3H]Choline incorporation into phosphatidylCholine. The activity of Choline-Phosphate Cytidylyltransferase was elevated in the type IIB cells and the extent of the increase was diminished when phosphatidylglycerol was included in the assay, suggesting that the enhanced activity was due to enzyme activation rather than protein synthesis. The basal rate of phosphatidylCholine secretion was the same in all three groups as was the response to a variety of secretagogues. Incorporation of [3H]acetate into fatty acids was elevated in type IIB cells and the activity of fatty acid synthase was eightfold greater than in control cells. These data show that de novo fatty acid biosynthesis is increased in hypertrophic type II cells and that surfactant secretion is not elevated.
Douglas A. Feldman - One of the best experts on this subject based on the ideXlab platform.
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[29] Choline-Phosphate Cytidylyltransferase
Methods in enzymology, 1992Co-Authors: Paul A. Weinhold, Douglas A. FeldmanAbstract:Publisher Summary Choline-Phosphate Cytidylyltransferase (CTP:CholinePhosphate Cytidylyltransferase) catalyzes a major rate-determining step in the biosynthesis of phosphatidylCholine in mammalian cells. Both cytosolic and membrane fractions contain Choline-Phosphate Cytidylyltransferase activity. Enzyme activity is determined by measuring the formation of radioactive CDPCholine from phospho[methyl- 14 C]Choline. Two methods have been used to separate CDPCholine from phosphoCholine: adsorption of CDPCholine by charcoal or separation of CDPCholine from phosphoCholine by thin-layer chromatography. The charcoal adsorption method is rapid, sensitive, and reproducible. The ability to perform many assays (50–100) per day is an additional advantage. A variety of lipids have been used by investigators for the assay of Cytidylyltransferase. It has been a common practice to include lipid in assays involving soluble forms of Cytidylyltransferase. The molecular and kinetic properties of Cytidylyltransferase are discussed this chapter.
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microsomal ctp Choline Phosphate Cytidylyltransferase kinetic mechanism of fatty acid stimulation
Biochimica et Biophysica Acta, 1991Co-Authors: Paul A. Weinhold, Linda G Charles, Douglas A. FeldmanAbstract:Fatty acids are known to cause an increase in the incorporation of radioactive Choline into phosphatidylCholine. A coincident increase in membrane Cytidylyltransferase activity is well documented. The purpose of the present studies was to determine the direct effects of oleic acid on the kinetic properties of membrane Cytidylyltransferase. An examination of the reaction characteristics of membrane Cytidylyltransferase revealed that membranes from adult rat lung contained high CTPase activity. This activity prevented the determination of reaction velocities at low CTP concentrations. The CTPase activity was blocked by the addition of ADP or ATP to the reaction. The addition of 6.0 mM ADP to the assay mixture enabled us to determine the effect of oleate on the CTP K,,,. Oleate (122 p'.:) caused a significant decrease in CTP K m for microsomal Cytidylyltransferase (0.99 mM to 0.33 raM) and H-Form ¢ytidylyltransferase (1.04 mM to 0.27 raM). Oleate did not decrease the CTP K~ for L-Form ¢ytidylyltransferase. Oleate had no effect on the Choline Phosphate K m in microsomal, H-Form or L-Form cytidylyitransferase. Oleate also increased the Vmx for Cytidylyltransferase. The increase was dependent upon the concentration of oleate with a maximal increase of 50-60% at 100-130 /zM oleate. We conclude that oleate has a direct stimulatory effect on Cytidylyltransferase when it is in the active form (membrane bound or H-Form lipoprotein complex). We suggest that the kinetic cffccts operate synergistically witlt oi|te,' i egttlaiory tnechal|i.~tt|Is such as translocation or conversion of inactive to active species. The direct effect of oleate on the Cytidylyltransferase may be an important regulatory mechanism when CTP concentrations are limiting.
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Control of phosphatidylCholine synthesis in Hep G2 cells. Effect of fatty acids on the activity and immunoreactive content of Choline Phosphate Cytidylyltransferase.
The Journal of biological chemistry, 1991Co-Authors: P.a. Weinhold, L Charles, M E Rounsifer, Douglas A. FeldmanAbstract:Abstract We examined the effect of fatty acids on phosphatidylCholine synthesis and Cytidylyltransferase activity in Hep G2 cells. Treatment of Hep G2 cells with oleic acid caused an increase in the incorporation of [methyl-14C]Choline into phosphatidylCholine and a corresponding decrease in radioactivity in Choline Phosphate using a pulse-chase procedure. This result is consistent with a fatty acid-induced increase in the cytidylyl-transferase step in the Choline pathway. We measured Cytidylyltransferase activity in membrane fractions and in cytosol (100,000 x g supernatant or soluble enzyme released by digitonin). The activity increased in both membrane and cytosol. Thus, an increase in total activity occurred. Cytidylyltransferase protein determined by Western blot immunoassay increased after oleic acid treatment. Immunotitration of Cytidylyltransferase protein also indicated that an increase in enzyme protein resulted from oleic acid treatment. Cycloheximide did not prevent the oleic acid-induced increase in Cytidylyltransferase activity. The increase in enzyme activity was apparent when we measured the activity in the presence or absence of lipid activators. Separation of cytosolic Cytidylyltransferase into H- and L-forms showed that the increase in cytosolic activity was due to an increase in H-form. The amount of L-form did not change. We interpret these results to suggest that fatty acid treatment of Hep G2 cells promoted the formation of active Cytidylyltransferase (H-form) from a preexisting inactive form. The increased activity was distributed between membranes and the lipoprotein form in cytosol (H-form).
J. Rami - One of the best experts on this subject based on the ideXlab platform.
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Fatty-acid synthase activity and mRNA level in hypertrophic type II cells from silica-treated rats.
The American journal of physiology, 1994Co-Authors: J. Rami, S. M. Sasic, W Stenzel, C Puel-m'rini, J P Besombes, J A Elias, S A RooneyAbstract:Silica instillation causes a massive increase in lung surfactant. Two populations of type II pneumocytes can be isolated from rats administered silica by intratracheal injection: type IIA cells similar to type II cells from normal rats and type IIB cells, which are larger and contain elevated levels of surfactant protein A and phospholipid. Activities of Choline-Phosphate Cytidylyltransferase, a rate-regulatory enzyme in phosphatidylCholine biosynthesis, and fatty-acid synthase (FAS) are increased in type IIB cells isolated from rats 14 days after silica injection. In the present study, we examined the increase in FAS and Cytidylyltransferase activities in type IIB cells as a function of time after silica administration. FAS activity increased rapidly, was approximately threefold elevated 1 day after silica administration and has reached close to the maximum increase by 3 days. Cytidylyltransferase activity was not increased on day 1, was significantly increased on day 3 but was not maximally increased until day 7. Inhibition of de novo fatty-acid biosynthesis, by in vivo injection of hydroxycitric acid and inclusion of agaric acid in the type II cell culture medium, abolished the increase in Cytidylyltransferase activity on day 3 but not FAS and had no effect on activities of two other enzymes of phospholipid synthesis. FAS mRNA levels were not increased in type IIB cells isolated 1-14 days after silica injection. These data show that the increase in FAS activity in type IIB cells is an early response to silica, that it mediates the increase in Cytidylyltransferase activity, and that it is not due to enhanced FAS gene expression.
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Enhanced fatty acid biosynthesis and normal surfactant secretion in hypertrophic rat type II cells.
American Journal of Physiology-Lung Cellular and Molecular Physiology, 1991Co-Authors: J. Rami, S. M. Sasic, Seamus A. RooneyAbstract:Silica instillation causes lung surfactant accumulation as well as hyperplasia and hypertrophy of type II pneumocytes. Two populations of type II cells can be isolated from silica-treated rats: type IIA, which are similar to type II cells from normal animals and type IIB, which are larger and have a higher rate of phosphatidylCholine biosynthesis. We have compared fatty acid biosynthesis and phosphatidylCholine secretion in types IIA and IIB cells and in type II cells from control rats. The cells were isolated by elastase digestion and panning on immunoglobulin G-coated plates and fractionated into types IIA and IIB by centrifugal elutriation. Type IIB cells contained more phospholipid and had an enhanced rate of [3H]Choline incorporation into phosphatidylCholine. The activity of Choline-Phosphate Cytidylyltransferase was elevated in the type IIB cells and the extent of the increase was diminished when phosphatidylglycerol was included in the assay, suggesting that the enhanced activity was due to enzyme activation rather than protein synthesis. The basal rate of phosphatidylCholine secretion was the same in all three groups as was the response to a variety of secretagogues. Incorporation of [3H]acetate into fatty acids was elevated in type IIB cells and the activity of fatty acid synthase was eightfold greater than in control cells. These data show that de novo fatty acid biosynthesis is increased in hypertrophic type II cells and that surfactant secretion is not elevated.