Sestrins (Sesns) protect cells from oxidative stress. The mechanism underlying the antioxidant effect of Sesns has remained unknown, however. The Nrf2-Keap1 pathway provides cellular defense against oxidative stress by controlling the expression of antioxidant enzymes. We now show that Sesn1 and Sesn2 interact with the Nrf2 suppressor Keap1, the autophagy substrate p62, and the ubiquitin ligase Rbx1 and that the antioxidant function of Sesns is mediated through activation of Nrf2 in a manner reliant on p62-dependent autophagic degradation of Keap1. Sesn2 was upregulated in the liver of mice subjected to fasting or subsequent refeeding with a high-carbohydrate, fat-free diet, whereas only refeeding promoted Keap1 degradation and Nrf2 activation, because only refeeding induced p62 expression. Ablation of Sesn2 blocked Keap1 degradation and Nrf2 activation induced by refeeding and thereby increased the susceptibility of the liver to oxidative damage resulting from the acute stimulation of lipogenesis associated with refeeding.

Methionine in proteins is often thought to be a generic hydrophobic residue, functionally replaceable with another hydrophobic residue such as valine or leucine. This is not the case, and the reason is that methionine contains sulfur that confers special properties on methionine. The sulfur can be oxidized, converting methionine to methionine sulfoxide, and ubiquitous methionine sulfoxide reductases can reduce the sulfoxide back to methionine. This redox cycle enables methionine residues to provide a catalytically efficient antioxidant defense by reacting with oxidizing species. The cycle also constitutes a reversible post-translational covalent modification analogous to phosphorylation. As with phosphorylation, enzymatically-mediated oxidation and reduction of specific methionine residues functions as a regulatory process in the cell. Methionine residues also form bonds with aromatic residues that contribute significantly to protein stability. Given these important functions, alteration of the methionine-methionine sulfoxide balance in proteins has been correlated with disease processes, including cardiovascular and neurodegenerative diseases. Methionine isn't just for protein initiation.

Reversible oxidative inactivation of centrosome-bound protein phosphatases such as Cdc14B by H2O2 is likely responsible for the inhibition of Cdk1-opposing phosphatases during early mitosis, which prevents premature degradation of mitotic activators.

Background: The Advanced Lung Cancer Inflammation Index (ALI, body mass index × albumin/neutrophil-to-lymphocyte ratio) has been demonstrated to be a prognostic factor of survival in some solid cancers. We retrospectively investigated the usefulness of the ALI to predict chemotherapy response and survival in 212 patients with diffuse large B cell lymphoma (DLBCL) treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) chemotherapy. Methods: Patients were allocated to a low ALI group (n = 82, 38.7%) or a high ALI group (n = 130, 61.3%) according to an optimal pretreatment ALI cut-off value of 15.5 as determined by receiver operating curve analysis. Results: The low ALI group displayed more adverse clinical characteristics, lower rates of complete remission (54.9 vs. 75.4%, p = 0.008), and poorer 5-year progression-free (PFS, 58.1 vs. 77.3%, p = 0.006) and overall (OS, 64.2 vs. 80.2%, p = 0.008) survival. Multivariate analysis showed that low ALI was found to independently predict shorter PFS and OS. Interestingly, a low ALI reverted to a high ALI during treatment in 58 patients (27.4%), and the 5-year OS of these patients was better than that of patients whose ALI remained low (n = 24, 72.5 vs. 24%, p < 0.001). Conclusions: ALI might be an easily available marker for predicting clinical outcomes in DLBCL patients treated with R-CHOP chemotherapy.

A new fluorescence turn-on probe that responds exclusively to H(2)O(2) exhibits subcellular localized fluorescence staining of lysosomes.