Transgenic overexpression of glutathione S-transferase μ-type 1 reduces hypertension and oxidative stress in the stroke-prone spontaneously hypertensive rat

Abstract

Background: Combined congenic breeding and microarray gene expression profiling previously identified glutathione S-transferase m-type 1 (Gstm1) as a positional and functional candidate gene for blood pressure (BP) regulation in the stroke-prone spontaneously hypertensive (SHRSP) rat. Renal Gstm1 expression in SHRSP rats is significantly reduced when compared with normotensive Wistar Kyoto (WKY) rats. As Gstm1 plays an important role in the secondary defence against oxidative stress, significantly lower expression levels may be functionally relevant in the development of hypertension. The aim of this study was to investigate the role of Gstm1 in BP regulation and oxidative stress by transgenic overexpression of the Gstm1 gene. Method: Two independent Gstm1 transgenic SHRSP lines were generated by microinjecting SHRSP embryos with a linear construct controlled by the EF-1a promoter encoding WKY Gstm1 cDNA [SHRSP-Tg(Gstm1)1 WKY and SHRSP-Tg(Gstm1)2 WKY ]. Results: Transgenic rats exhibit significantly reduced BP and pulse pressure when compared with SHRSP [systolic: SHRSP 205.2 AE 3.7 mmHg vs. SHRSP-Tg(Gstm1)1 WKY 175.5 AE 1.6 mmHg and SHRSP-Tg(Gstm1)2 WKY 172 AE 3.2 mmHg, P < 0.001; pulse pressure: SHRSP 58.4 AE 0.73 mmHg vs. SHRSP-Tg(Gstm1)1 WKY 52.7 AE 0.19 mmHg and SHRSP-Tg(Gstm1)2 WKY 40.7 AE 0.53 mmHg, P < 0.001]. Total renal and aortic Gstm1 expression in transgenic animals was significantly increased compared with SHRSP [renal relative quantification (RQ): SHRSP-Tg(Gstm1)1 WKY 1.95 vs. SHRSP 1.0, P < 0.01; aorta RQ: SHRSP-Tg(Gstm1)1 WKY 2.8 vs. SHRSP 1.0, P < 0.05]. Renal lipid peroxidation (malondialdehyde: protein) and oxidized : reduced glutathione ratio levels were significantly reduced in both transgenic lines when compared with SHRSP [malondialdehyde: SHRSP 0.04 AE 0.009 mmol/l vs. SHRSP-Tg(Gstm1)1 WKY 0.024 AE 0.002 mmol/l and SHRSP-Tg(Gstm1)2 WKY 0.021 AE 0.002 mmol/l; (oxidized : reduced glutathione ratio): SHRSP 5.19 AE 2.26 mmol/l vs. SHRSP-Tg(Gstm1)1 WKY 0.17 AE 0.11 mmol/l and SHRSP-Tg(Gstm1)2 WKY 0.47 AE 0.22 mmol/l]. Transgenic SHRSP rats containing the WKY Gstm1 gene demonstrate significantly lower BP, reduced oxidative stress and improved levels of renal Gstm1 expression. Conclusion: These data support the hypothesis that reduced renal Gstm1 plays a role in the development of hypertension.

GSTM1 Deletion Exaggerates Kidney Injury in Experimental Mouse Models and Confers the Protective Effect of Cruciferous Vegetables in Mice and Humans

“…Our result is consistent with a recent study showing that transgenic overexpression of Gstm1 in the kidney injury-prone SHRSP rat rescued renal oxidative stress and HTN. 45 In the AngII-HTN model, there was no difference in SBP between WT and KO mice and we speculate that the very high dose of AngII administered potentially masked any modest BP effect of Gstm1 deletion.…”

“…Furthermore, enzyme kinetic assays have demonstrated that GSTM1 has activity against epoxides 47 and several reactive aldehydes [48][49][50] and, in vivo, transgenic overexpression of Gstm1 in the SHRSP rat decreases renal levels of malondialdehyde. 45 The multiple substrates metabolized by GSTM1 suggest that their metabolites and downstream effects may be influenced by disease states. Identification of reactive oxygen species regulated by GSTM1 that are involved in kidney injury in these models would be informative to further elucidate the mechanisms.…”

The Relationship of Glutathione-S-Transferase and Multi-Drug Resistance-Related Protein 1 in Nitric Oxide (NO) Transport and Storage

“…Given the role of the MRP1 and GST P1-1 system in NO transport and storage in tumor cells ( Figure 7 ) [ 132 , 134 , 162 , 175 ], it is of great interest that GST polymorphisms correlate with preeclampsia (high blood pressure in pregnancy), potentially because GSTs bind vasoactive NO as DNICs [ 215 ]. Furthermore, using a combination of congenic breeding and microarray gene expression profiling, Olson and colleagues have identified Gst m1 as a positional and functional candidate gene involved in blood pressure regulation [ 216 ]. This latter study also identified that transgenic SHRSP rats harboring the WKY Gst m1 gene exhibited significantly lower blood pressure and reduced oxidative stress, which are associated with hypertension and organ damage [ 216 ].…”

“…Furthermore, using a combination of congenic breeding and microarray gene expression profiling, Olson and colleagues have identified Gst m1 as a positional and functional candidate gene involved in blood pressure regulation [ 216 ]. This latter study also identified that transgenic SHRSP rats harboring the WKY Gst m1 gene exhibited significantly lower blood pressure and reduced oxidative stress, which are associated with hypertension and organ damage [ 216 ].…”

Genetic Complementation of ATP Synthase Deficiency Due to Dysfunction of TMEM70 Assembly Factor in Rat

“…Its major advantage lies in their size and larger blood volume compared to mice as well as their better accessibility in contrast to larger animals [ 52 ]. The feasibility of rat model has dwindled since transgenic technologies were first pioneered in mice, but recent advances also make genetic manipulation available for rats [ 53 , 54 , 55 , 56 ]. We performed our studies in SHR (spontaneously hypertensive rat) inbred rats since they represent one of the best characterized rat models of cardiac hypertrophy [ 57 ], which is associated also with Tmem70 dysfunction in humans [ 33 ].…”