Interaction between hydrogen sulfide-induced sulfhydration and tyrosine nitration in the K_ATP channel complex

Abstract

Hydrogen sulfide (H₂S) is an endogenous gaseous mediator affecting many physiological and pathophysiological conditions. Enhanced expression of H2S and reactive nitrogen/oxygen species (RNS/ROS) during inflammation alters cellular excitability via modulation of ion channel function. Sulfhydration of cysteine residues and tyrosine nitration are the posttranslational modifications induced by H₂S and RNS, respectively. The objective of this study was to define the interaction between tyrosine nitration and cysteine sulfhydration within the ATP-sensitive K(+) (KATP) channel complex, a significant target in experimental colitis. A modified biotin switch assay was performed to determine sulfhydration of the KATP channel subunits, Kir6.1, sulphonylurea 2B (SUR2B), and nitrotyrosine measured by immunoblot. NaHS (a donor of H₂S) significantly enhanced sulfhydration of SUR2B but not Kir6.1 subunit. 3-Morpholinosydnonimine (SIN-1) (a donor of peroxynitrite) induced nitration of Kir6.1 subunit but not SUR2B. Pretreatment with NaHS reduced the nitration of Kir6.1 by SIN-1 in Chinese hamster ovary cells cotransfected with the two subunits, as well as in enteric glia. Two specific mutations within SUR2B, C24S, and C1455S prevented sulfhydration by NaHS, and these mutations prevented NaHS-induced reduction in tyrosine nitration of Kir6.1. NaHS also reversed peroxynitrite-induced inhibition of smooth muscle contraction. These studies suggest that posttranslational modifications of the two subunits of the KATP channel interact to alter channel function. The studies described herein demonstrate a unique mechanism by which sulfhydration of one subunit modifies tyrosine nitration of another subunit within the same channel complex. This interaction provides a mechanistic insight on the protective effects of H₂S in inflammation.

Protein S‐sulfhydration by hydrogen sulfide in cardiovascular system

“…This might be the key mechanism for H 2 S to act as an endothelial derived relaxing factor. Kang et al also found that H 2 S increased S‐sulfhydration on sulphonylurea 2B (SUR2B) at Cys24 and Cys1455, another subunit of K ATP channels complex, to restore smooth muscle contraction (Kang et al, ). Liu et al found that H 2 S decreased the membrane potential, inhibited the fast inactivation component of the voltage‐dependent potassium channel current in gastric smooth muscle cells and promoted gastric motility, which was suppressed by KV4.3 knockdown.…”

“…That is S‐sulfhydration of SUB2B at C24S and C1455S inhibited the nitration of K ir 6.1. Moreover, NaHS also reduced the tyrosine nitration of Ca v 1.2b channels to improve Ca 2+ ‐induced contractions in mouse ileum (Kang et al, ). In accord with the previous study, NaHS reduced the activity of L‐Ca 2+ channels containing free sulfhydryl groups in cardiomyocytes (Zhang et al, ).…”

Role of epithelial ion transports in inflammatory bowel disease

“…In lymphatic vessels of TNBS-inflamed guinea pig ileum, NO stimulates the cGMP/ PKG pathway, upregulating mRNA level and activity of K ATP channels, which impairs lymphatic pumping (96). On the other hand, hydrogen sulfide (H 2 S) beneficial effects on colitis severity and mortality have been attributed to the activation of K ATP channels through S-sulfhydration of the SUR2B subunit (47,65,140). K ATP channels are present in the basolateral membrane of the rat colonocytes, but their exact composition is still unknown (109).…”

ABCC9/SUR2 in the brain: Implications for hippocampal sclerosis of aging and a potential therapeutic target

“…Although biochemical regulation of the K ATP channel function is incompletely understood, particularly in the brain, a number of post-translational modifications have been reported. For example, SUR2 is affected directly by glycosylation, sulfhydration, and protein kinase A phosphorylation (Gade, et al, 2013,Gao, et al, 2014,Kang, et al, 2014,Light, 1996). The K ATP channel is also regulated via separate phosphorylation event(s) in the Kir6.x channels (Edwards, et al, 2009,Ko, et al, 2008,Sanada and Kitakaze, 2004,Sun, et al, 2008), again showing complex functional interdependence of these proteins.…”