S‐nitrosoglutathione reductase is essential for reducing ischemia‐reperfusion injury in female hearts by metabolizing formaldehyde
Authors: Kohr Mark Jeffrey , Casin Kevin , Mackowski Nathan , Veenema Ryne , Chan Ashley , St. Paul Amanda , Bedja Djahida , Biswal Shyam 
Published: June 2021

Reversible forms of cysteine oxidation, including protein S‐nitrosation (SNO), have been implicated as essential mediators of nitric oxide‐dependent cardioprotection. Compared to males, female hearts exhibit higher baseline levels of protein SNO, and associated with this, reduced susceptibility to myocardial ischemia‐reperfusion (I/R) injury. Female hearts also exhibit enhanced S‐nitrosoglutathione reductase (GSNOR) activity, which typically favors decreased SNO levels since GSNOR is a major mediator of protein SNO catabolism. Since female hearts exhibit higher protein SNO levels, we hypothesized that GSNOR is an essential component of sex‐dependent cardioprotection in females. Male and female wildtype mouse hearts were subjected to ex vivo I/R injury via Langendorff perfusion with or without GSNOR inhibition (N6022). Control female hearts exhibited enhanced functional recovery and decreased infarct size vs. control males. Interestingly, GSNOR inhibition reversed this sex disparity, significantly reducing injury in male hearts, and exacerbating injury in females. Similar results were obtained with male and female GSNOR−/− hearts. Assessment of SNO levels using SNO‐resin assisted capture revealed an increase in total SNO protein levels with N6022 in male hearts, whereas total SNO protein levels remained unchanged in female hearts. Upon closer examination of specific SNO‐modified proteins, we found that while N6022 significantly increased SNO at the cardioprotective Cys39 residue of NADH dehydrogenase subunit 3 (ND3) in males, SNO‐ND3 levels were surprisingly reduced in N6022‐treated female hearts and this may contribute to injury by promoting an increase in post‐ischemic reactive oxygen species production. However, N6022 actually induced a significant reduction in post‐ischemic reactive oxygen species production in both male and female hearts, which is consistent with the increase in SNO‐ND3 levels observed in males, but suggests an alternative mechanism of injury in females. Since GSNOR is also a major formaldehyde dehydrogenase in the heart, we examined post‐ischemic formaldehyde levels and found that these levels were nearly 2‐fold higher in N6022‐treated female hearts compared to all other treatment groups (control male/female, N6022‐treated male). Excitingly, pre‐ischemic myocardial administration of Alda‐1, an activator of the mitochondrial isoform of the formaldehyde metabolizing enzyme aldehyde dehydrogenase 2 (ALDH2), reduced infarct size in female GSNOR−/− hearts, but provided no additional benefit to male GSNOR−/− hearts. This rescue experiment suggests that the accumulation of mitochondrial formaldehyde may exacerbate I/R injury in female hearts. Taken together, our striking findings point to GSNOR as a critical sex‐dependent mediator of myocardial protein SNO and formaldehyde levels, and suggest that different therapeutic strategies may be required to combat ischemic heart disease in males and females.Support or Funding InformationThis work was supported by the National Institutes of Health (T32ES0741, KC; R00HL114721, MK; R01CA206166, SB; U01ES026721, SB), and the American Heart Association (12BGIA11780030, MK).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.