The expression of an intestinal form of glutathione peroxidase (GSHPx-GI) in rat intestinal epithelium.
We have previously identified and characterized GSHPx-GI, which is a cellular selenium-dependent glutathione peroxidase (GSHPx) distinct from the classic GSHPx-1 and phospholipid hydroperoxide glutathione peroxidase (PHGPX). We have determined the level of GSHPx-GI mRNA expression in the rat gastrointestinal tract from esophagus to colon. Although GSHPx-GI mRNA is readily detectable throughout the GI tract, the highest level is detected in the ileum and cecum. We have also determined the levels of GSHPx-GI mRNA expression and several antioxidant enzyme activities along the villus-to-crypt axis in the rat small intestine by cell fractionation. GSHPx-GI mRNA is present at a similar level in all of the epithelial fractions, whereas GSHPx-1 mRNA is detectable only in the remnant. This suggests that GSHPx-GI is the major cellular tetrameric GSHPx expressed in intestinal epithelium, and the expression of GSHPx-GI in the GI tract is not likely regulated differentially through maturation of epithelial cells. In terms of enzymatic activity, although we detected lower glutathione S-transferase activity in the crypt epithelium, there was a marginal increase of PHGPX activity, a twofold increase of GSHPx activity, and a three- to fivefold increase of catalase activity in the crypt relative to the distal villus. Thus, the crypt epithelial cells may be better protected from peroxidative damage.
D000818:Animals; D004848:Epithelium / Q000201:enzymology; D015870:Gene Expression; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D007413:Intestinal Mucosa / Q000201:enzymology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase