Microsomal glutathione S-transferases: selective up-regulation of leukotriene C4 synthase during lipopolysaccharide-induced pyresis

Abstract

Cysteinyl-leukotrienes (cys-LTs) are potent smooth muscle contracting agents, which play key roles in inflammatory and allergic diseases. The committed step in cys-LT biosynthesis is catalyzed by leukotriene C(4) synthase (LTC4S) as well as microsomal glutathione S-transferase type 2 (MGST2) and type 3 (MGST3). Here we report that intraperitoneal injections of lipopolysaccharide in rats lead to a strong increase of LTC4S messenger RNA (mRNA) levels after approximately 1 h, particularly in the heart, brain, adrenal glands and liver, without any significant effect on MGST2 and MGST3 mRNA levels. After 6 h, LTC4S mRNA returns to basal levels, concomitant with a 4.9-, 4.0-, 2.9- and 2.3-fold induction of LTC4S protein in brain, heart, liver and adrenal gland, respectively. Hence, challenge with lipopolysaccharide in vivo causes an organ-selective, local priming for leukotriene C(4) synthesis. Moreover, these data suggest that LTC4S and cys-LTs may be involved in acute systemic inflammatory responses such as fever and tachycardia.

Differential induction of BLT receptor expression on human endothelial cells by lipopolysacharide, cytokines, and leukotriene B4

“…For identification of the BLT 1 and BLT 2 mRNA, the corresponding DNA fragments generated by RT-PCR were sequenced by using the DYEnamic ET terminator cycle sequencing premix kit (Amersham Pharmacia). For semiquantitative analysis of PCR products, the fluorescent dye PicoGreen (Molecular Probes) was used as described (31,32). The fluorescence was measured ( ex ϭ 485 nm; em ϭ 538 nm) in a SpectraMax GeminiXS fluorometer from Molecular Devices.…”

Increased Leukotriene C4 Synthesis Accompanied Enhanced Leukotriene C4 Synthase Expression and Activities of Ischemia–Reperfusion-Injured Liver in Rats

“…Immunoblot analysis was performed as described previously but with a slight modification [27]. Briefly,100 g membrane protein in loading buffer was separated by SDS-PAGE through a 15% Tris-HCl, precasted, linear gradient gel and electroblotted onto PVDF membranes (Millipore).…”

“…(Color version of figure is available online.) ride [22], and lipopolysaccharide [27,29,34]. Although a growing body of evidence implicates LTs in the pathogenesis of the hepatic I/R injury [16,23,26,[35][36][37][38][39][40], the mechanisms of LTC4 alteration during hepatic I/R were not well elucidated, so we used a rat model of hepatic ischemia 60 min and 5 h reperfusion and tried a series of experiments to explore it.…”

“…More recent reports indicated that lipopolysaccharide led to LTC4S but not mGST2 or mGST3 mRNA increase after approximately 1 h and returned to basal levels after 6 h, concomitant with an induction of LTC4S protein in the heart, brain, adrenal glands, and liver [27]. However, the alterations in the mRNA and protein levels of mGST2 and mGST3, the cell types responsible for the expressions of LTC4S, mGST2, and mGST3, and the activities of LTC4 synthesis enzymes (LTC4S, mGST2, and mGST3) during hepatic I/R are not studied previously; the mechanism that influenced LTC4 generation in the early phase of hepatic I/R injury is far from being elucidated.…”

A molecular understanding of ATP-dependent solute transport by multidrug resistance-associated protein MRP1

“…LTC4 is synthesized in mast cells, basophils, eosinophils, dendritic cells, macrophages, neutrophils, platelets, kidney and brain [190,191]. LTC4 can also be produced in liver microsomes and endothelial cells [192,193]. Although whether the LTC4 synthesized in these cells is exported by MRP1 protein is not convincingly established, leukotriene release from eosinophils and mast cells in response to IgEmediated inflammation is reduced in Mrp1 −/− knockout mice [51].…”