Tissue Specific Expression of the Plasma Glutathione Peroxidase Gene in Rat Kidney1

Abstract

Rat plasma glutathione peroxidase (GSH-Px) was purified 1,400-fold from rat serum by a combination of phenyl Sepharose, DEAE Sephacel, blue Sepharose and Sephacryl S-200 column chromatographies. The purified GSH-Px migrated as a single band corresponding to a molecular weight of 22,500 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was used for the immunization of chickens to obtain a specific antibody and for determination of its amino acid sequence. Two overlapping cDNA clones for rat plasma GSH-Px were isolated from a placental cDNA library. The composite nucleotide sequence is 1,529 base-pairs long and encodes 226 amino acids. The deduced amino acid sequence completely coincided with the sequences of five individual peptide fragments derived from the purified plasma GSH-Px on digestion with lysyl endopeptidase. In order to identify the tissue(s) generating this plasma GSH-Px, immunoblot analysis was performed on homogenates prepared from 13 tissues. A single immunoreactive band of 22.5 kDa, corresponding to plasma GSH-Px, was detected for the kidney homogenate. A much fainter band was observed for the lung preparation, but liver, spleen, bone marrow, and other tissues examined were negative. Northern blot analysis further revealed that the expression level of the plasma GSH-Px gene was high in kidney and low in lung. No transcript was detected in liver or spleen. These results indicate that plasma GSH-Px is predominantly synthesized and secreted by renal cells.

Acute effects of microcystins exposure on the transcription of antioxidant enzyme genes in three organs (liver, kidney, and testis) of male Wistar rats

“…Plasma GPx (GPx3) and phospholipid GPx (GPx4), mainly expressed in kidney and testis, respectively [34,35], were significantly induced in the present study. GPx3 is proposed to be a major scavenger of ROS in the extracellular space and within the vasculature [36].…”

Loss of selenium from selenoproteins: Conversion of selenocysteine to dehydroalanine in vitro

“…We studied glutathione peroxidase, which had been purified from rat plasma. This selenoprotein is a homotetramer that contains a selenocysteine at residue 54 of each subunit [6]. The protein was reduced, alkylated, and digested using Glu-C.…”

Involvement of Lipid Peroxidation in the Alteration of Protein Kinase C Signaling

“…Most H 2 O 2 and LOOH are reduced by glutathione peroxidase (GPX). In mammalian cells, classical GPX (cGPX), plasma GPX (pGPX), intestinal GPX (iGPX) and phospholipid hydroperoxide glutathione peroxidase (PHGPX) have been isolated and functionally characterized [5,20,26,27,33,37,46]. Our study showed that PHGPX could reduce DAG-OOH to DAG-OH, an inactive form of neutrophil stimulation, in the presence of reduced form of glutathione, whereas cGPX and pGPX could not [19].…”