Arachidonate 5-lipoxygenase of porcine pancreas: its localization in acinar cells

doi:10.1016/0005-2760(91)90100-V

Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism

Volume 1085, Issue 2, 11 September 1991, Pages 241-247

Biochimica et Biophy...

https://doi.org/10.1016/0005-2760(91)90100-V Get rights and content

Abstract

Arachidonate 5-lipoxygenase has been found so far in various types of leukocyte. When a homogenate of porcine pancreas was incubated with arachidonic acid, 5-hydroxy-6,8,11,14-eicosatetraenoic acid was predominantly produced concomitant with small amounts of compounds derived from leukotriene A₄. After differential centrifugation of the homogenate, the 5-lipoxygenase activity was found predominantly in the 1000 × g pellet and 105 000 × g supernatant. When porcine pancreas was investigated immunohistochemically with anti-5-lipoxygenase antibody, Langerhans islets were unstained, and infiltration of 5-lipoxygenase-positive leukocytes was hardly observed. In contrast, acinar cells were positively stained. Immunoelectron microscopy demonstrated the localization of the enzyme along the nuclear membranes of the acinar cells.

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Acinar Cell Production of Leukotriene B<inf>4</inf> Contributes to Development of Neurogenic Pancreatitis in Mice
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Citation Excerpt :
Very little is known about leukotriene production in the pancreas. It was previously been shown by others that porcine34 and human22 pancreatic acinar cells express 5-LO and can synthesize LTB4. In addition, the human pancreas also expresses FLAP,35 but no information was available about the distribution of 5-LO in the mouse pancreas or the effects of inflammatory agents on pancreatic 5-LO activity.
In the pancreas, activation of primary sensory nerves through the transient receptor potential vanilloid-1 (TRPV1) ion channel contributes to the early stages of development of pancreatitis. Little is known about the mechanism by which this occurs. We investigated whether leukotriene B₄ (LTB₄) is an endogenous agonist of TRPV1 and mediates pancreatitis.
Acute inflammation was induced in the pancreata of Trpv1^−/− mice and their wild-type littermates by retrograde infusion of the main pancreatic duct with 2% sodium taurocholate (NaT) or intraperitoneal injections of caerulein. Mice were also given injections of resiniferatoxin (an excitotoxin that desensitizes TRPV1) or MK886 (a drug that inhibits LTB₄ biosynthesis). Pancreatic tissues and plasma were collected and analyzed.
Retrograde perfusion of the main pancreatic ducts of wild-type mice with NaT caused severe acute pancreatitis; the severity was reduced by coadministration of resiniferatoxin. Trpv1^−/− mice developed a less severe pancreatitis after NaT administration compared with controls. Administration of MK886 before perfusion with NaT also significantly reduced the severity of pancreatitis in wild-type mice. Pancreatic tissues from mice given NaT had a marked increase in the level of 5-lipoxygenase immunoreactivity specifically in acinar cells. Bile acid and caerulein induced secretion of LTB₄ by cultured pancreatic acinar cells; MK886 inhibited this process.
Administration of caerulein or intraductal bile acids in mice causes production of LTB₄ by pancreatic acinar cells. This activates TRPV1 on primary sensory nerves to induce acute pancreatitis.
5-Lipoxygenase and leukotriene B<inf>4</inf> receptor are expressed in human pancreatic cancers but not in pancreatic ducts in normal tissue
2002, American Journal of Pathology
Citation Excerpt :
Immunohistochemistry studies have only shown the 5-LOX expression in porcine pancreatic acinar cells but not in porcine Langerhans islets or ductal cells.25 Staining was localized along the nuclear membranes of the acinar cells, demonstrated by immunoelectron microscopy.25 5-LOX expression and distribution was also investigated in rat pancreas, but no evidence of 5-LOX antigen or enzymatic activity was found in exocrine pancreas, purified β-cells, or other islet cells.39
The 5-lipoxygenase (5-LOX) pathway is critical for pancreatic cancer cell growth and escape from apoptosis. Inhibition of 5-LOX blocks proliferation and induces apoptosis in human pancreatic cancer cells. However, the expression of 5-LOX and its downstream signaling pathway have not been investigated in human pancreatic adenocarcinoma. Reverse transcriptase-polymerase chain reaction revealed expression of 5-LOX mRNA in all pancreatic cancer cell lines tested including, PANC-1, AsPC-1, and MiaPaCa2 cells, but not in normal pancreatic ductal cells. The expression of 5-LOX protein in pancreatic cancer cell lines was demonstrated by Western blotting. Finally, 5-LOX up-regulation in human pancreatic cancer tissues was verified by intense positive staining in cancer cells by immunohistochemistry. Staining for the 5-LOX protein was particularly evident in the ductal components of the more differentiated tumors but not in ductal cells in normal pancreatic tissues from cadaver donors. Immunohistochemistry also revealed strong staining of cancer tissues with an antibody to the receptor of the downstream 5-LOX metabolite, leukotriene B₄. The current study demonstrated marked expression of 5-LOX and the leukotriene B₄ receptor in human pancreatic cancer tissues. These findings provide further evidence of up-regulation of this pathway in pancreatic cancer and that LOX inhibitors are likely to be valuable in the treatment of this dreadful disease.
Translocation of the 85-kDa phospholipase A<inf>2</inf> from cytosol to the nuclear envelope in rat basophilic leukemia cells stimulated with calcium ionophore or IgE/antigen
1995, Journal of Biological Chemistry
The rat mast cell line RBL-2H3.1 contains an 85-kDa cytosolic phospholipase A² (cPLA²) that is very likely involved in liberating arachidonate from membrane phospholipid for the synthesis of eicosanoids following stimulation with either calcium ionophore or IgE/antigen. In this study, the intracellular location of cPLA² was determined using immunofluorescence microscopy and immuno-gold electron microscopy. In nonstimulated cells, cPLA² is distributed throughout the cytosol and is excluded from the nucleoplasm. Following cell activation with calcium ionophore, most of the cPLA² translocates to the nuclear envelope, and the enzyme remains there during the entire period that ionophore is present. With IgE/antigen stimulation for 5 min, approximately 20-30% of the cPLA² translocates to the nuclear envelope, and after 30 min of stimulation, most of the enzyme returns to the cytosol. Measurement of intracellular calcium using the dye Fura-2/AM shows that the level of calcium rises immediately after antigen is added, remains high for about 30 s, and then declines back to resting levels. Activation with calcium ionophore produces a 10-fold larger release of arachidonate than does stimulation with IgE/antigen. Thus, the results suggest that the extent of membrane binding of cPLA² correlates with the release of arachidonate and that the site of arachidonate liberation is the nuclear envelope where many of the enzymes that oxygenate this fatty acid are located.
Molecular Biology in the Eicosanoid Field
1993, Progress in Nucleic Acid Research and Molecular Biology
This chapter describes the molecular biology in the eicosanoid field. Molecular biology made its main entrance to the eicosanoid field, when two groups simultaneously reported the cloning of the cDNA for leukotriene A₄ hydrolase. Subsequently, the field has expanded considerably to include many interesting findings with the lipoxygenases, prostaglandin-synthesizing enzymes, and prostanoid receptors. Availability of the genes for these enzymes should allow targeting strategies to discern potential functions. Clear information on the regulation and significance of leukotriene formation by 5-lipoxygenase, 5-lipoxygenase activating protein, and leukotriene A₄ hydrolase is still lacking. The recent discovery of the second form of cyclooxygenase has reopened a wide interest in the academic and pharmaceutical communities in prostaglandin research. The differential regulation of the two cyclooxygenase forms and the development of selective isoform inhibitors will be the areas of intensive research. Cloning of the different members of the eicosanoid receptor family should facilitate our unravelling of the mechanisms involved in the action of this interesting class of arachidonate metabolites known as eicosanoids.
Mammalian lipoxygenases: molecular structures and functions
1992, Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Role of lipoxygenase pathways in the regulation of pancreatic cancer cell proliferation and survival
2001, Inflammopharmacology

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Regular paperArachidonate 5-lipoxygenase of porcine pancreas: its localization in acinar cells

Abstract

J. Biol. Chem.

Prostaglandins Leukotrienes Ess. Fatty Acids

J. Biol. Chem.

J. Biol. Chem.

Prostaglandins

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

J. Biol. Chem.

Biochem. Biophys. Res. Commun.

Biochim. Biophys. Acta

Regular paper
Arachidonate 5-lipoxygenase of porcine pancreas: its localization in acinar cells