Abstract MP58: Tissue And Sex Specific Effects Of Gstm1 Deletion In Mouse Models

Abstract

The glutathione S-transferase ( Gst ) gene family encodes antioxidant enzymes. In humans, a common null allele deletion variant of GST μ-1 ( GSTM1 ) is highly prevalent across populations and is associated with increased risk and progression of various diseases. Using a Gstm1 knockout (KO) mouse model, we previously showed that KO mice with angiotensin II-induced hypertension (HTN) have increased kidney injury compared to wild-type (WT) controls, mediated by elevated oxidative stress. In the same mouse model, we have recently reported that in a Langendorff-perfused cardiac ischemia-reperfusion injury (IRI) model, where damage is also mediated by oxidative stress, male KO hearts are protected while females are not. Here, we investigated the molecular mechanisms for this difference in male hearts. WT and KO mice of both sexes were studied at 12-20 weeks of age. Hearts were snap frozen at baseline and after 25 min of global ischemia, and kidneys were collected at baseline and 4 weeks following HTN induction. A panel of 18 Gst genes were probed by qPCR from baseline hearts and kidneys of both sexes. Global metabolites were assayed using Metabolon, Inc. from hearts of both sexes and kidneys of males, at both baseline and diseased states. Analysis by qPCR (n = 3/group) showed that male, but not female, KO hearts had upregulation of other Gst s. In contrast, no significant differences between were found in male kidneys. Metabolomics (n = 6/group) detected 695 metabolites in hearts and 926 in kidneys. There were increases in several metabolites in KO vs. WT hearts including those with antioxidant properties. Notably, increases in carnosine and anserine were observed in KO male hearts but not in female hearts, while that of other antioxidant-related metabolites were observed in hearts of both sexes, but not in kidneys. HTN induced significant increases in metabolites in KO vs. WT kidneys in the pathways related to and linking methionine, cysteine, and glutathione, which were not observed in hearts. In this study, gene expression and metabolites suggest that the mechanisms compensating for the loss of GSTM1 are both tissue and sex specific. The resulting differences in antioxidant enzymes and metabolites may explain the unexpected protection for male Gstm1 KO hearts in IRI.