Dataset Information

S-nitrosoglutathione reductase deficiency increases mutagenesis from alkylation in mouse liver.

ABSTRACT: In human hepatocellular carcinoma (HCC) and many other cancers, somatic point mutations are highly prevalent, yet the mechanisms critical in their generation remain poorly understood. S-nitrosoglutathione reductase (GSNOR), a key regulator of protein S-nitrosylation, is frequently deficient in human HCC. Targeted deletion of the GSNOR gene in mice can reduce the activity of the DNA repair protein O (6)-alkylguanine-DNA alkyltransferase (AGT) and promote both carcinogen-induced and spontaneous HCC. In this study, we report that following exposure to the environmental carcinogen diethylnitrosamine, the mutation frequency of a transgenic reporter in the liver of GSNOR-deficient mice (GSNOR(-/-)) is significantly higher than that in wild-type control. In wild-type mice, diethylnitrosamine treatment does not significantly increase the frequency of the transition from G:C to A:T, a mutation deriving from diethylnitrosamine-induced O (6)-ethylguanines that are normally repaired by AGT. In contrast, the frequency of this transition from diethylnitrosamine is increased ~20 times in GSNOR(-/-) mice. GSNOR deficiency also significantly increases the frequency of the transversion from A:T to T:A, a mutation not affected by AGT. GSNOR deficiency in our experiments does not significantly affect either the frequencies of the other diethylnitrosamine-induced point mutations or hepatocyte proliferation. Thus, GSNOR deficiency, through both AGT-dependent and AGT-independent pathways, significantly raises the rates of specific types of DNA mutations. Our results demonstrate a critical role for GSNOR in maintaining genomic integrity in mice and support the hypothesis that GSNOR deficiency is an important cause of the widespread mutations in human HCC.

SUBMITTER: Leung J

PROVIDER: S-EPMC3643423 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

S-nitrosoglutathione reductase deficiency increases mutagenesis from alkylation in mouse liver.

Leung James J Wei Wei W Liu Limin L

Carcinogenesis 20130125 5

In human hepatocellular carcinoma (HCC) and many other cancers, somatic point mutations are highly prevalent, yet the mechanisms critical in their generation remain poorly understood. S-nitrosoglutathione reductase (GSNOR), a key regulator of protein S-nitrosylation, is frequently deficient in human HCC. Targeted deletion of the GSNOR gene in mice can reduce the activity of the DNA repair protein O (6)-alkylguanine-DNA alkyltransferase (AGT) and promote both carcinogen-induced and spontaneous HC ...[more]

PMID: 23354311

Similar Datasets

Project description:Induced pluripotent stem cells (iPSCs) provide a model of cardiomyocyte (CM) maturation. Nitric oxide signaling promotes CM differentiation and maturation, although the mechanisms remain controversial. The study tested the hypothesis that in the absence of S-nitrosoglutathione reductase (GSNOR), a denitrosylase regulating protein S-nitrosylation, the resultant increased S-nitrosylation accelerates the differentiation and maturation of iPSC-derived cardiomyocytes (CMs). iPSCs derived from mice lacking GSNOR (iPSCGSNOR-/-) matured faster than wildtype iPSCs (iPSCWT) and demonstrated transient increases in expression of murine Snail Family Transcriptional Repressor 1 gene (Snail), murine Snail Family Transcriptional Repressor 2 gene (Slug) and murine Twist Family BHLH Transcription Factor 1 gene (Twist), transcription factors that promote epithelial-to-mesenchymal transition (EMT) and that are regulated by Glycogen Synthase Kinase 3 Beta (GSK3β). Murine Glycogen Synthase Kinase 3 Beta (Gsk3β) gene exhibited much greater S-nitrosylation, but lower expression in iPSCGSNOR-/-. S-nitrosoglutathione (GSNO)-treated iPSCWT and human (h)iPSCs also demonstrated reduced expression of GSK3β. Nkx2.5 expression, a CM marker, was increased in iPSCGSNOR-/- upon directed differentiation toward CMs on Day 4, whereas murine Brachyury (t), Isl1, and GATA Binding Protein (Gata4) mRNA were decreased, compared to iPSCWT, suggesting that GSNOR deficiency promotes CM differentiation beginning immediately following cell adherence to the culture dish-transitioning from mesoderm to cardiac progenitor. Together these findings suggest that increased S-nitrosylation of Gsk3β promotes CM differentiation and maturation from iPSCs. Manipulating the post-translational modification of GSK3β may provide an important translational target and offers new insight into understanding of CM differentiation from pluripotent stem cells. Deficiency of GSNOR or addition of GSNO accelerates early differentiation and maturation of iPSC-cardiomyocytes.

Project description:Protein S-nitrosylation plays a fundamental role in cell signaling and nitrosoglutathione (GSNO) is considered as the main nitrosylating signaling molecule. Enzymatic systems controlling GSNO homeostasis are thus crucial to indirectly control the formation of protein S-nitrosothiols. GSNO reductase (GSNOR) is the key enzyme controlling GSNO levels by catalyzing its degradation in the presence of NADH. Here, we found that protein extracts from the microalga Chlamydomonas reinhardtii catabolize GSNO via two enzymatic systems having specific reliance on NADPH or NADH and different biochemical features. Scoring the Chlamydomonas genome for orthologs of known plant GSNORs, we found two genes encoding for putative and almost identical GSNOR isoenzymes. One of the two, here named CrGSNOR1, was heterologously expressed and purified. Its kinetic properties were determined and the three-dimensional structures of the apo-, NAD+- and NAD+/GSNO-forms were solved. These analyses revealed that CrGSNOR1 has a strict specificity towards GSNO and NADH, and a conserved folding with respect to other plant GSNORs. The catalytic zinc ion, however, showed an unexpected variability of the coordination environment. Furthermore, we evaluated the catalytic response of CrGSNOR1 to thermal denaturation, thiol-modifying agents and oxidative modifications as well as the reactivity and position of accessible cysteines. Despite being a cysteine-rich protein, CrGSNOR1 contains only two solvent-exposed/reactive cysteines. Oxidizing and nitrosylating treatments have null or limited effects on CrGSNOR1 activity and folding, highlighting a certain resistance of the algal enzyme to redox modifications. The molecular mechanisms and structural features underlying the response to thiol-based modifications are discussed. Highlights • Chlamydomonas protein extracts catalyze NAD(P)H-dependent GSNO degradation.• Chlamydomonas GSNOR1 is a zinc-containing protein strictly relying on GSNO and NADH.• The 3D-structure of CrGSNOR1 revealed a conserved folding with other plant GSNORs.• CrGSNOR1 contains only two solvent-exposed/reactive cysteines.• Oxidizing and nitrosylating treatments have limited effects on CrGSNOR1 activity.

Dataset Information

S-nitrosoglutathione reductase deficiency increases mutagenesis from alkylation in mouse liver.

Publications

S-nitrosoglutathione reductase deficiency increases mutagenesis from alkylation in mouse liver.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets