Posttranslational modification of Sirt6 activity by peroxynitrite

Abstract

The mammalian sirtuin 6 (Sirt6) is a site-specific histone deacetylase that regulates chromatin structure and many fundamental biological processes. It inhibits endothelial cell senescence and inflammation, prevents development of cardiac hypertrophy and heart failure, modulates glucose metabolism, and represses tumor growth. The basic molecular mechanisms underlying regulation of Sirt6 enzymatic function are largely unknown. Here we hypothesized that Sirt6 function can be regulated via posttranslational modification, focusing on the role of peroxynitrite, one of the major reactive nitrogen species formed by excessive nitric oxide and superoxide generated during disease processes. We found that incubation of purified recombinant Sirt6 protein with 3-morpholinosydnonimine (SIN-1, a peroxynitrite donor that generates nitric oxide and superoxide simultaneously) increased Sirt6 tyrosine nitration and decreased its intrinsic catalytic activity. Similar results were observed in SIN-1-treated Sirt6 which was overexpressed in HEK293 cells, and on endogenous Sirt6 when human retinal microvascular endothelial cells were treated with SIN-1. To further investigate whether Sirt6 nitration occurs under pathological conditions, we determined Sirt6 nitration and activity in retina using a model of endotoxin-induced retinal inflammation. Our data showed that Sirt6 nitration was increased while its activity was decreased in this model. With mass spectrometry, we identified that tyrosine 257 in Sirt6 was nitrated after SIN-1 treatment. Mutation of tyrosine 257 to phenylalanine caused loss of Sirt6 activity, and abolished SIN-1-induced nitration and decrease in its activity. Mass spectrometry analysis also revealed oxidation of methionine and tryptophan in Sirt6 after SIN-1 treatment. Our results demonstrate a novel regulatory mechanism controlling Sirt6 activity through reactive nitrogen species-mediated post-translational modification under oxidative and nitrosative stress.

SIRT1 and SIRT6 Signaling Pathways in Cardiovascular Disease Protection

“…It has been hypothesized that, under oxidative and nitrosative stress, SIRT6 activity can be regulated via reactive nitrogen species-mediated posttranslational modifications (71). Indeed, incubation of purified recombinant SIRT6 protein with 3-morpholinosydnonimine, a donor of peroxynitrite, increased nitration at tyrosine 257 and decreased the catalytic activity (71).…”

Post-translational modifications of nuclear sirtuins

“…In addition, significantly increased SIRT6 nitration and decreased deacetylase activity of SIRT6 were also found in an endotoxin-induced retinal inflammation mice model, indicating that SIRT6 nitration is correlated to retinal inflammation. In summary, tyrosine nitration may act as a novel regulatory mechanism to negatively control SIRT6 activity (Hu et al 2015).…”

Synergistic Interaction of Light Alcohol Administration in the Presence of Mild Iron Overload in a Mouse Model of Liver Injury: Involvement of Triosephosphate Isomerase Nitration and Inactivation

“…Protein tyrosine nitration is a kind of posttranslational modification when tissues under nitrative stress. It was reported that nitration of mitochondrial proteins led to their inactivation and mitochondrial dysfunction[44], and a recent report revealed that nitration of Y257 in sirtuin 6 inhibited its function [45]. Nitration of TIM at Y165 and Y209 has been demonstrated to induce a decrease in its activity [46].…”