A novel persulfide detection method reveals protein persulfide and polysulfide-reducing functions of thioredoxin and glutathione systems

Hydrogen sulfide signaling involves persulfide formation at specific protein Cys residues. However, overcoming current methodological challenges in persulfide detection and elucidation of Cys regeneration mechanisms from persulfides are prerequisites for constructing a bona fide signaling model. We here establish a novel, highly specific protein persulfide detection protocol, ProPerDP, with which we quantify 1.52 ± 0.6 and 11.6 ± 6.9 μg/mg protein steady-state protein persulfide concentrations in human embryonic kidney 293 (HEK293) cells and mouse liver, respectively. Upon treatment with polysulfides, HEK293 and A549 cells exhibited increased protein persulfidation. Deletion of the sulfide-producing cystathionine-γ-lyase or cystathionine-β-synthase enzymes in yeast diminished protein persulfide levels, thereby corroborating their involvement in protein persulfidation processes. We here establish that thioredoxin (Trx) and glutathione (GSH) systems can independently catalyze reductions of inorganic polysulfides and protein persulfides. Increased endogenous persulfide levels and protein persulfidation following polysulfide treatment in thioredoxin reductase-1 (TrxR1) or thioredoxin-related protein of 14 kDa (TRP14) knockdown HEK293 cells indicated that these enzymes constitute a potent regeneration system of Cys residues from persulfides in a cellular context. Furthermore, TrxR1-deficient cells were less viable upon treatment with toxic amounts of polysulfides compared to control cells. Emphasizing the dominant role of cytosolic disulfide reduction systems in maintaining sulfane sulfur homeostasis in vivo, protein persulfide levels were markedly elevated in mouse livers where hepatocytes lack both TrxR1 and glutathione reductase (TR/GR-null). The different persulfide patterns observed in wild-type, GR-null, and TR/GR-null livers suggest distinct roles for the Trx and GSH systems in regulating subsets of protein persulfides and thereby fine-tuning sulfide signaling pathways.USD 1,500 APC fee funded by the EC FP7 Post-Grant Open Access Pilot

When MIPVU goes to no man’s land: a new language resource for hybrid, morpheme-based metaphor identification in Hungarian

The aim of the article is to present a new language resource for metaphor analysis in corpora that is (i) a MIPVU-inspired, morpheme-based process for identifying metaphor in Hungarian and (ii) the refinement and innovative version of metaphor identification extending the scope of the process to multi-word expressions. The elaboration of language-specific protocols in metaphor identification has become one of the central endeavors in contemporary cross-linguistic research on metaphor, but there is a gap in the field regarding languages with rich morphology, especially in the case of Hungarian. To fill this gap, we developed a hybrid, morpheme-based version of the original method, which can handle morphologically complex metaphorical expressions. Additional innovations of our protocol are the measurement and tagging of idiomaticity in metaphors based on collocation analysis and the identification of semantic relationships between the components of metaphorical expressions. The present paper discusses both the theoretical motivation and the practical details of the adapted method for metaphor identification. As a conclusion, the presented protocol can provide new answers to the questions of metaphor identification in languages with rich morphology and shed new light on the internal semantic organization of linguistic metaphors