Pre-eclampsia: the Potential of GSNO Reductase Inhibitors.

PURPOSE OF REVIEW: Pre-eclampsia remains a leading worldwide cause of maternal death and of perinatal morbidity. There remains no definitive treatment except delivery of the fetus. RECENT FINDINGS: Recent insights into the cardiovascular changes that are evident prior to, during, and persist after pre-eclampsia have improved understanding of the underlying pathophysiology-disruption of normal endothelial function and decreased nitric oxide bioavailability. S-nitrosoglutathione (GSNO) is an endogenous S-nitrosothiol that acts as a NO pool and, by replenishing or preventing the breakdown of GSNO, endothelial dysfunction can be ameliorated. GSNO reductase inhibitors are a novel class of drug that can increase NO bioavailability. GSNO reductase inhibitors have demonstrated improvement of endothelial dysfunction in animal models, and in vivo human studies have shown them to be well tolerated. GSNOR inhibitors offer a potentially promising option for the management of pre-eclampsia.

Medium-chain fatty acids and glutathione derivatives as inhibitors of S-nitrosoglutathione reduction mediated by alcohol dehydrogenase 3.

Alcohol dehydrogenase 3 (ADH3) has emerged as an important regulator of protein S-nitrosation in its function as S-nitrosoglutathione (GSNO) reductase. GSNO depletion is associated with various disease conditions, emphasizing the potential value of a specific ADH3 inhibitor. The present study investigated inhibition of ADH3-mediated GSNO reduction by various substrate analogues, including medium-chain fatty acids and glutathione derivatives. The observed inhibition type was non-competitive. Similar to the Michaelis constants for the corresponding omega-hydroxy fatty acids, the inhibition constants for fatty acids were in the micromolar range and showed a clear dependency on chain length with optimal inhibitory capacity for eleven and twelve carbons. The most efficient inhibitors found were undecanoic acid, dodecanoic acid and dodecanedioic acid, with no significant difference in inhibition constant. All glutathione-derived inhibitors displayed inhibition constants in the millimolar range, at least three orders of magnitudes higher than the Michaelis constants of the high-affinity substrates GSNO and S-hydroxymethylglutathione. The experimental results as well as docking simulations with GSNO and S-methylglutathione suggest that for ADH3 ligands with a glutathione scaffold, in contrast to fatty acids, a zinc-binding moiety is imperative for correct orientation and stabilization of the hydrophilic glutathione scaffold within a predominantly hydrophobic active site.

Nitric oxide controls nuclear export of APE1/Ref-1 through S-nitrosation of cysteines 93 and 310.

Apurinic/apyrimidinic endonuclease 1/redox effector factor-1 (APE1/Ref-1, abbreviated as APE1) is a molecule with dual functions in DNA repair and redox regulation of transcription factors. Accumulated work has shown that the biological activities of APE1 are sensitive to oxidative stress; however, whether APE1 functions can be regulated by nitrosative stress remains unknown. In this investigation, we found that S-nitrosoglutathion (GSNO), a nitric oxide donor and also an S-nitrosating agent, effectively stimulated nuclear export of APE1 in a CRM1-independent manner. This nuclear-cytoplasmic translocation was dependent on S-nitrosation modification of APE1, as simultaneous mutation of S-nitrosation target sites Cys93 and Cys310 completely abrogated the cytoplasmic redistribution. The translocation process was reversal and specific, as it could be reversed by reductive reagents, but could not be mimicked by H2O2. In structure, the region aa.64-80 and the beta-strand aa.311-316 in proximity to Cys93 and Cys310 were important for GSNO-induced APE1 relocalization. In addition, a defect of importin-mediated nuclear import pathway was found in the NO-insulted cells, and p50 and HDAC2 were identified as APE1 nuclear export inhibitory proteins. Together, this study may provide a novel molecular mechanism, which links nitrosative stress to APE1-associated physiological and pathological processes.