Genetic Deficiency of Glutathione S -Transferase P Increases Myocardial Sensitivity to Ischemia–Reperfusion Injury

Abstract

Rationale Myocardial ischemia-reperfusion (I/R) results in the generation of oxygen-derived free radicals and the accumulation of lipid peroxidation-derived unsaturated aldehydes. However, the contribution of aldehydes to myocardial I/R injury has not been assessed. Objective We tested the hypothesis that removal of aldehydes by glutathione S-transferase P (GSTP) diminishes I/R injury. Methods and Results In adult male C57BL/6 mouse hearts, Gstp1/2 was the most abundant GST transcript followed by Gsta4 and Gstm4.1, and GSTP activity was a significant fraction of the total GST activity. mGstp1/2 deletion reduced total GST activity, but no compensatory increase in GSTA and GSTM or major antioxidant enzymes was observed. Genetic deficiency of GSTP did not alter cardiac function, but in comparison with hearts from wild-type (WT) mice, the hearts isolated from GSTP-null mice were more sensitive to I/R injury. Disruption of the GSTP gene also increased infarct size after coronary occlusion in situ. Ischemia significantly increased acrolein in hearts, and GSTP deficiency induced significant deficits in the metabolism of the unsaturated aldehyde, acrolein, but not in the metabolism 4-hydroxy-trans-2-nonenal (HNE) or trans-2-hexanal; and, upon ischemia, the GSTP-null hearts accumulated more acrolein-modified proteins than WT hearts. GSTP-deficiency did not affect I/R-induced free radical generation, JNK activation or depletion of reduced glutathione. Acrolein-exposure induced a hyperpolarizing shift in INa, and acrolein-induced cell death was delayed by SN-6, a Na+/Ca++ exchange inhibitor. Cardiomyocytes isolated from GSTP-null hearts were more sensitive than WT myocytes to acrolein-induced protein crosslinking and cell death. Conclusions GSTP protects the heart from I/R injury by facilitating the detoxification of cytotoxic aldehydes such as acrolein.

Albumin Cys34 adducted by acrolein as a marker of oxidative stress in ischemia-reperfusion injury during hepatectomy

“…Others have demonstrated that ACR is released after I/R damage in the heart [37] and in the retina of rats [38]. Here, we first demonstrated, to our knowledge, that ACR is the main RCS formed during liver reperfusion in humans.…”

Glutathione s-transferase p in glucose homeostasis in mice.

“…Thus, enzymatic conjugation by GSTP facilitates and enhances the detoxification and removal of acrolein and other related aldehydes [52]. The physiological relevance of this metabolic proclivity is supported by studies in rodents that demonstrate a role for GSTP in protection against cardiovascular toxicity of direct acrolein exposure and acrolein-containing tobacco smoke as well as cyclophosphamide-induced urotoxicity and cardiotoxicity, and myocardial ischemia/reperfusion injury [59][60][61][62] . Among all the αβ-unsaturated aldehydes, acrolein is by far the strongest electrophile and reacts 100-fold more rapidly with thiols than 4-HNE [96,97] …”

“…GSTP-deficient (GSTPnull) did not show any obvious phenotype, although some null mice had higher body weights than controls [56]. Studies using GSTP-null mice have elucidated GSTP to be an important metabolic determinant of 7,12-dimethylbenz anthracene (DMBA)-induced carcinogenesis [56], APAP-induced hepatotoxicity [57], allergic airways disease [58], tobacco-induced endothelial dysfunction [59], cyclophosphamide-induced urinary bladder and cardio-toxicity [60] and more recently myocardial sensitivity to ischemia-reperfusion injury [61,62]. GSTP was also found to be a major GST isoform in the heart, lung and aorta and contributed significantly to total GST conjugating activity in those tissues.…”

“…Chapter V summarizes the overall conclusions derived from this thesis work and presents recommendations for future work. GSTP-null mice, generated on a MF1 background strain using homologous recombination [56], were bred for >12 generations with C57BL/6J mice as previously described [61]. Mice heterozygous for the targeted locus (F1) were crossed to generate wild-type (WT) and KO littermates.…”

“…While the role of these adducts in JNK activation is unclear, the accumulation of these adducts reflects a loss of acrolein removal capacity that is consistent with the decreased overall GSTP abundance and GST activity (using CDNB as substrate), in livers of HFDfed WT mice. Previously, we used organ-specific protein-acrolein adducts as both a metric of acrolein exposure (as with tobacco smoke; [59]) but also as an arbiter of cardiac injury in models of ischemia-reperfusion [61] and cyclophosphamide toxicity [62]. Whereas other studies have demonstrated an increase in oxidative stress markers such as hepatic malondialdehyde and ROS measurements [141], to our knowledge this is the first report of direct protein modification by acrolein in liver, linked to obesity.…”