scholarly journals Rat liver mitochondrial phospholipase A2 is an endotoxin-stimulated membrane-associated enzyme of Kupffer cells which is released during liver perfusion

1993 ◽  
Vol 293 (1) ◽  
pp. 143-150 ◽  
Author(s):  
G M Hatch ◽  
D E Vance ◽  
D C Wilton
Keyword(s):  
Enzyme Activity ◽  
Phospholipase A2 ◽  
Rat Liver ◽  
Kupffer Cells ◽  
Hepatic Lipase ◽  
Liver Perfusion ◽  
Elevated Serum ◽  
Physiological Saline ◽  
Group Ii ◽  
Phospholipase A2 Activity

A novel fluorescence assay for phospholipase A2 [Wilton (1990) Biochem. J. 266, 435-439] has been used to study the Group-II rat liver mitochondrial enzyme, and a number of novel properties of this enzyme were identified. (1) The enzyme activity was located in the liver macrophages (Kupffer cells) while negligible activity was associated with hepatocytes. (2) Although subcellular fractionation of whole liver confirmed the predominantly mitochondrial location of this enzyme activity, the analysis of the hepatocyte-free Kupffer-cell-enriched fraction revealed a different enzyme distribution, with the majority of activity being associated with the microsomal membrane fraction. (3) Bacterial endotoxin has been previously shown to be scavenged by Kupffer cells in rats. Treatment of rats with bacterial lipopolysaccharide (endotoxin) resulted in a dramatic time- and dose-dependent increase in liver phospholipase A2 activity. (4) It is known that injection of endotoxin into rodents results in elevated serum phospholipase A2 activity, while a similar phenomenon is seen in the condition of septic shock in man. The source of this serum enzyme was unknown. In this study perfusion of livers from rats pretreated with lipopolysaccharide with physiological saline demonstrated a 6-fold increase in phospholipase A2 activity in the perfusate compared with sham-treated controls, with only minor release of hepatic lipase. (5) Western-blot analysis confirmed an increased release of this Group-II phospholipase A2 into the perfusate of lipopolysaccharide-treated rats compared with sham-treated controls. These results suggest that liver Kupffer cells are a major source of the endotoxin-induced serum Group-II phospholipase A2 activity associated with bacterial infection and trauma.

scholarly journals Phospholipase A2 of rat liver mitochondria in vitamin E deficiency

1978 ◽  
Vol 172 (2) ◽  
pp. 349-352 ◽  
Author(s):  
A. S. Pappu ◽  
P. Fatterpaker ◽  
A. Sreenivasan
Keyword(s):  
Enzyme Activity ◽  
Vitamin E ◽  
Phospholipase A2 ◽  
Rat Liver ◽  
Fold Increase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Vitamin E Deficiency ◽  
Phospholipase A2 Activity

1. There is a more than 2-fold increase in phospholipase A2 activity (EC 3.1.1.4) of liver mitochondria isolated from vitamin E-deficient rats compared with that in normal rats. 2. α-Tocopherol in lipoprotein-bound form is more effective than free α-tocopherol in restoring the enzyme activity to normal.

Serum phospholipase A2 activity and immunoreactive group II phospholipase A2 in rheumatoid arthritis

1995 ◽  
Vol 236 (1) ◽  
pp. 109-112 ◽  
Author(s):  
Takanori Komatsubara ◽  
Hiromasa Tojo ◽  
Zhao Ying ◽  
Tetsuya Tomita ◽  
Takahiro Ochi ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Phospholipase A2 ◽  
Group Ii ◽  
Phospholipase A2 Activity

scholarly journals Hepatic lipase is localized at the parenchymal cell microvilli in rat liver

1997 ◽  
Vol 321 (2) ◽  
pp. 425-430 ◽  
Author(s):  
Belinda BREEDVELD ◽  
Kees SCHOONDERWOERD ◽  
Adrie J. M. VERHOEVEN ◽  
Rob WILLEMSEN ◽  
Hans JANSEN
Keyword(s):  
Endothelial Cells ◽  
Rat Liver ◽  
Kupffer Cells ◽  
Binding Capacity ◽  
Hepatic Lipase ◽  
Parenchymal Cell ◽  
Liver Cells ◽  
Minor Amount ◽  
Parenchymal Liver ◽  
Parenchymal Cells

Hepatic lipase (HL) is thought to be located at the vascular endothelium in the liver. However, it has also been implicated in the binding and internalization of chylomicron remnants in the parenchymal cells. In view of this apparent discrepancy between localization and function, we re-investigated the localization of HL in rat liver using biochemical and immunohistochemical techniques. The binding of HL to endothelial cells was studied in primary cultures of rat liver endothelial cells. Endothelial cells bound HL in a saturable manner with high affinity. However, the binding capacity accounted for at most 1% of the total HL activity present in the whole liver. These results contrasted with earlier studies, in which non-parenchymal cell (NPC) preparations had been found to bind HL with a high capacity. To study HL binding to the different components of the NPC preparations, we separated endothelial cells, Kupffer cells and blebs by counterflow elutriation. Kupffer cells and endothelial cells showed a relatively low HL-binding capacity. In contrast, the blebs, representing parenchymal-cell-derived material, had a high HL-binding capacity (33 m-units/mg of protein) and accounted for more than 80% of the total HL binding in the NPC preparation. In contrast with endothelial and Kupffer cells, the HL-binding capacity of parenchymal cells could account for almost all the HL activity found in the whole liver. These data strongly suggest that HL binding occurs at parenchymal liver cells. To confirm this conclusion in situ, we studied HL localization by immunocytochemical techniques. Using immunofluorescence, we confirmed the sinusoidal localization of HL. Immunoelectron microscopy demonstrated that virtually all HL was located at the microvilli of parenchymal liver cells, with a minor amount at the endothelium. We conclude that, in rat liver, HL is localized at the microvilli of parenchymal cells.

The effect of endotoxin on the activity of group II rat liver phospholipase A2

1994 ◽  
Vol 22 (3) ◽  
pp. 316S-316S ◽  
Author(s):  
WAI J. MAN ◽  
PIERS TOMLINSON ◽  
DAVID C. WILTON
Keyword(s):  
Phospholipase A2 ◽  
Rat Liver ◽  
Group Ii

scholarly journals Effects of dexamethasone and transforming growth factor-β2 on group II phospholipase A2 mRNA and activity levels in interleukin 1β- and forskolin-stimulated mesangial cells

1996 ◽  
Vol 315 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Margriet J. B. M. VERVOORDELDONK ◽  
Casper G. SCHALKWIJK ◽  
Josef PFEILSCHIFTER ◽  
Henk van den BOSCH
Keyword(s):  
Enzyme Activity ◽  
Growth Factor ◽  
Phospholipase A2 ◽  
Inflammatory Cytokines ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Interleukin 1Β ◽  
Mrna Levels ◽  
Transforming Growth Factor Β2 ◽  
Group Ii

The expression of 14 kDa group II phospholipase A2 [also referred to as secretory PLA2 (sPLA2)] is induced in rat glomerular mesangial cells by exposure to inflammatory cytokines and forskolin, a cAMP elevating agent. Previously we have shown that dexamethasone and transforming growth factor-β2 (TGF-β2) suppress sPLA2 protein synthesis and enzyme activity induced by cytokines and forskolin. The regulation of sPLA2 by pro-inflammatory cytokines suggests that the enzyme may play a role in glomerular inflammatory reactions. In order to understand the regulation of sPLA2 in more detail, we investigated whether dexamethasone and TGF-β2 also suppress sPLA2 mRNA after its induction by either interleukin-1β (IL-1β) or forskolin. We found that IL-1β-induced sPLA2 mRNA in rat mesangial cells is not down-regulated by pretreatment of the cells with dexamethasone, even at a concentration of 10 μM, which dramatically decreases sPLA2 protein levels and activity. Metabolic labelling experiments indicated that the decreased sPLA2 levels under these conditions can be explained by inhibition of the rate of sPLA2 synthesis from the elevated mRNA levels. In contrast, the forskolin-induced elevation of sPLA2 mRNA is inhibited by dexamethasone in a concentration-dependent manner. Likewise, TGF-β2 inhibits the elevation of sPLA2 mRNAs induced by either IL-1β or forskolin. The decrease in sPLA2 mRNA caused by TGF-β2 corresponds with the decrease in sPLA2 enzyme levels and activity. These data suggest that cytokine- and forskolin-induced sPLA2 expression is tightly controlled via both transcriptional and post-transcriptional mechanisms. Furthermore, we show that pretreatment of mesangial cells with epidermal growth factor prior to stimulation with IL-1β or forskolin had no suppressing effect on sPLA2 levels or enzyme activity, as has been reported previously for osteoblasts.

Cloning of the cDNA coding for 14 kDa group II phospholipase A2 from rat liver

1993 ◽  
Vol 1169 (1) ◽  
pp. 1-11 ◽  
Author(s):  
R.H.N. Van Schaik ◽  
N.M. Verhoeven ◽  
F.W. Neijs ◽  
A.J. Aarsman ◽  
H. Van den Bosch
Keyword(s):  
Phospholipase A2 ◽  
Rat Liver ◽  
Group Ii

Age-related changes in rat liver plasma membrane phospholipase A2 activity

1986 ◽  
Vol 21 (3) ◽  
pp. 187-193 ◽  
Author(s):  
Diana H. Petkova ◽  
Albena B. Momchilova ◽  
Kamen S. Koumanov
Keyword(s):  
Plasma Membrane ◽  
Phospholipase A2 ◽  
Rat Liver ◽  
Liver Plasma Membrane ◽  
Age Related ◽  
Phospholipase A2 Activity ◽  
Age Related Changes

scholarly journals Construction and activity analyses of single functional mouse peroxiredoxin 6 (Prdx6)

2019 ◽  
Vol 63 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Lu-Lu Wang ◽  
Shi-Ying Lu ◽  
Pan Hu ◽  
Bao-Quan Fu ◽  
Yan-Song Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Glutathione Peroxidase ◽  
Phospholipase A2 ◽  
Peroxidase Activity ◽  
Glutathione Peroxidase Activity ◽  
Active Centre ◽  
Peroxiredoxin 6 ◽  
Raw264.7 Macrophages ◽  
Overlap Extension ◽  
Phospholipase A2 Activity

Abstract Introduction: Peroxiredoxin 6 (Prdx6) is a bifunctional protein with glutathione peroxidase activity and phospholipase A2 activity. Previous studies have shown a significant positive correlation between the intracellular survival ability of Brucella and Prdx6. Here, the Prdx6 enzyme with a single activity was constructed to facilitate study of the relationship between the single function of Prdx6 and Brucella infection. Material and Methods: The target open reading frame (ORF) DNAs of Prdx6 with a single active centre were prepared using gene splicing by overlap extension PCR (SOE-PCR), and the recombinant eukaryotic expression plasmids inserted by Prdx6 with the single activity centre were constructed and transfected into murine Raw264.7 macrophages. The glutathione peroxidase activity and phospholipase A2 activity of the constructed Prdx6 were examined. Results: The core centres (Ser32 and Cys47) of Prdx6 were successfully mutated by changing the 94th nucleotide from T to G and the 140th nucleotide from G to C in the two enzyme activity cores, respectively. The constructed recombinant plasmids of Prdx6 with the single active centre were transfected into murine macrophages showing the expected single functional enzyme activity, which MJ33 or mercaptosuccinate inhibitors were able to inhibit. Conclusion: The constructed mutants of Prdx6 with the single activity cores will be a benefit to further study of the biological function of Prdx6 with different enzyme activity.

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