Ube2V2 Is a Rosetta Stone Bridging Redox and Ubiquitin Codes, Coordinating DNA Damage Responses

Organ-specific electrophile responsivity mapping in live C. elegans

Proximity labeling technologies are limited to indexing localized protein residents. Such data-although valuable-cannot inform on small-molecule responsivity of local residents. We here bridge this gap by demonstrating in live C. elegans how electrophile-sensing propensity in specific organs can be quantitatively mapped and ranked. Using this method, >70% of tissue-specific responders exhibit electrophile responsivity, independent of tissue-specific abundance. One responder, cyp-33e1-for which both human and worm orthologs are electrophile responsive-marshals stress-dependent gut functions, despite manifesting uniform abundance across all tissues studied. Cyp-33e1's localized electrophile responsivity operates site specifically, triggering multifaceted responses: electrophile sensing through the catalytic-site cysteine results in partitioning between enzyme inhibition and localized production of a critical metabolite that governs global lipid availability, whereas rapid dual-cysteine site-specific sensing modulates gut homeostasis. Beyond pinpointing chemical actionability within local proteomes, organ-specific electrophile responsivity mapping illuminates otherwise intractable locale-specific metabolite signaling and stress response programs influencing organ-specific decision-making.

RECON gene disruption enhances host resistance to enable genome-wide evaluation of intracellular pathogen fitness during infection

Transposon sequencing (Tn-seq) is a powerful genome-wide technique to assess bacterial fitness under varying growth conditions. However, screening via Tn-seq in vivo is challenging. Dose limitations and host restrictions create bottlenecks that diminish the transposon mutant pool being screened. Here, we have developed a murine model with a disruption in Akr1c13 that renders the resulting RECON-/- mouse resistant to high-dose infection. We leveraged this model to perform a Tn-seq screen of the human pathogen Listeria monocytogenes in vivo. We identified 135 genes which were required for L. monocytogenes growth in mice including novel genes not previously identified for host survival. We identified organ-specific requirements for L. monocytogenes survival and investigated the role of the folate enzyme FolD in L. monocytogenes liver pathogenesis. A mutant lacking folD was impaired for growth in murine livers by 2.5-log10 compared to wild type and failed to spread cell-to-cell in fibroblasts. In contrast, a mutant in alsR, which encodes a transcription factor that represses an operon involved in D-allose catabolism, was attenuated in both livers and spleens of mice by 4-log10 and 3-log10, respectively, but showed modest phenotypes in in vitro models. We confirmed that dysregulation of the D-allose catabolism operon is responsible for the in vivo growth defect, as deletion of the operon in the ∆alsR background rescued virulence. By undertaking an unbiased, genome-wide screen in mice, we have identified novel fitness determinants for L. monocytogenes host infection, which highlights the utility of the RECON-/- mouse model for future screening efforts.

IMPORTANCE

Listeria monocytogenes is the gram-positive bacterium responsible for the food-borne disease listeriosis. Although infections with L. monocytogenes are limiting in healthy hosts, vulnerable populations, including pregnant and elderly people, can experience high rates of mortality. Thus, understanding the breadth of genetic requirements for L. monocytogenes in vivo survival will present new opportunities for treatment and prevention of listeriosis. We developed a murine model of infection using a RECON-/- mouse that is restrictive to systemic L. monocytogenes infection. We utilized this model to screen for L. monocytogenes genes required in vivo via transposon sequencing. We identified the liver-specific gene folD and a repressor, alsR, that only exhibits an in vivo growth defect. AlsR controls the expression of the D-allose operon which is a marker in diagnostic techniques to identify pathogenic Listeria. A better understanding of the role of the D-allose operon in human disease may further inform diagnostic and prevention measures.

A monoclonal antibody that recognizes a unique 13-residue epitope in the cytoplasmic tail of HLA-E

The Class I MHC molecule (MHC-I) HLA-E presents peptides that are derived from the signal sequences, either those of other MHC-I products, or of viral type I membrane glycoproteins. Monoclonal antibodies with proven specificity for HLA-E, and with no cross-reactions with other MHC-I products, have yet to be described. To obtain anti-HLA-E-specific antibodies suitable for a range of applications, we generated monoclonal antibodies against a unique feature of HLA-E: its cytoplasmic tail. We created an immunogen by performing an enzymatically catalyzed transpeptidation reaction to obtain a fusion of the cytoplasmic tail of HLA-E with a nanobody that recognizes murine Class II MHC (MHC-II) products. We obtained a mouse monoclonal antibody that recognizes a 13-residue stretch in the HLA-E cytoplasmic tail. We cloned the genes that encode this antibody in expression vectors to place an LPETG sortase recognition motif at the C-terminus of the heavy and light chains. This arrangement allows the site-specific installation of fluorophores or biotin at these C-termini. The resulting immunoglobulin preparations, labeled with 4 equivalents of a fluorescent or biotinylated payload of choice, can then be used for direct immunofluorescence or detection of the tag by fluorescence or by streptavidin-based methods. We also show that the 13-residue sequence can serve as an epitope tag, independent of the site of its placement within a protein's sequence. The antibody can be used diagnostically to stain for HLA-E on patient tumor samples, it can be used as an antibody-epitope tag for extracellular proteins, and it enables research into the unique role of the cytoplasmic tail of HLA-E.

People with obesity exhibit losses in muscle proteostasis that are partly improved by exercise training

This pilot experiment examines if a loss in muscle proteostasis occurs in people with obesity and whether endurance exercise positively influences either the abundance profile or turnover rate of proteins in this population. Men with (n = 3) or without (n = 4) obesity were recruited and underwent a 14-d measurement protocol of daily deuterium oxide (D2O) consumption and serial biopsies of vastus lateralis muscle. Men with obesity then completed 10-weeks of high-intensity interval training (HIIT), encompassing 3 sessions per week of cycle ergometer exercise with 1 min intervals at 100% maximum aerobic power interspersed by 1 min recovery periods. The number of intervals per session progressed from 4 to 8, and during weeks 8-10 the 14-d measurement protocol was repeated. Proteomic analysis detected 352 differences (p < 0.05, false discovery rate < 5%) in protein abundance and 19 (p < 0.05) differences in protein turnover, including components of the ubiquitin-proteasome system. HIIT altered the abundance of 53 proteins and increased the turnover rate of 22 proteins (p < 0.05) and tended to benefit proteostasis by increasing muscle protein turnover rates. Obesity and insulin resistance are associated with compromised muscle proteostasis, which may be partially restored by endurance exercise.

Climbing into their Skin to Understand Contextual Protein-Protein Associations and Localizations: Functional Investigations in Transgenic Live Model Organisms

Borrowing some quotes from Harper Lee's novel "To Kill A Mockingbird" to help frame our manuscript, we discuss methods to profile local proteomes. We initially focus on chemical biology regimens that function in live organisms and use reactive biotin species for this purpose. We then consider ways to add new dimensions to these experimental regimens, principally by releasing less reactive (i. e., more selective) (preter)natural electrophiles. Although electrophile release methods may have lower resolution and label fewer proteins than biotinylation methods, their ability to probe simultaneously protein function and locale raises new and interesting possibilities for the field.

Electrophilic metabolites targeting the KEAP1/NRF2 partnership

Numerous electrophilic metabolites are formed during cellular activity, particularly under conditions of oxidative, inflammatory and metabolic stress. Among them are lipid oxidation and nitration products, and compounds derived from amino acid and central carbon metabolism. Here we focus on one cellular target of electrophiles, the Kelch-like ECH associated protein 1 (KEAP1)/nuclear factor erythroid 2 p45-related factor 2 (NRF2) partnership. Many of these reactive compounds modify C151, C273 and/or C288 within KEAP1. Other types of modifications include S-lactoylation of C273, N-succinylation of K131, and formation of methylimidazole intermolecular crosslink between two KEAP1 monomers. Modified KEAP1 relays the initial signal to transcription factor NRF2 and its downstream targets, the ultimate effectors that provide means for detoxification, adaptation and survival. Thus, by non-enzymatically covalently modifying KEAP1, the electrophilic metabolites discussed here serve as chemical signals connecting metabolism with stress responses.

Effect of ion migration on lead halide perovskite on visible light communication system

Benefiting from the high modulation bandwidth (BW), low energy consumption and excellent optical performance, lead halide perovskite has attracted wide attention in visible light communication (VLC). However, the ion migration which results in mobile point defects in perovskite structures is recognized as a crucial key factor inducing the performance degradation. Here, the influence of ion migration in perovskite devices on the performance of VLC was systematically studied. The ion migration process is realized by mixing CsPbBr3 and CsPbI3 quantum dots, during which, the performance of the VLC system is reduced, but it can return to its initial state after stabilization. The on-off keying (OOK) modulation scheme of the perovskite light-emitting diode (LED) device was carried out, achieving a data rate of 90 Mbps.

Z-REX: shepherding reactive electrophiles to specific proteins expressed tissue specifically or ubiquitously, and recording the resultant functional electrophile-induced redox responses in larval fish

This Protocol Extension describes the adaptation of an existing Protocol detailing the use of targetable reactive electrophiles and oxidants, an on-demand redox targeting toolset in cultured cells. The adaptation described here is for use of reactive electrophiles and oxidants technologies in live zebrafish embryos (Z-REX). Zebrafish embryos expressing a Halo-tagged protein of interest (POI)-either ubiquitously or tissue specifically-are treated with a HaloTag-specific small-molecule probe housing a photocaged reactive electrophile (either natural electrophiles or synthetic electrophilic drug-like fragments). The reactive electrophile is then photouncaged at a user-defined time, enabling proximity-assisted electrophile-modification of the POI. Functional and phenotypic ramifications of POI-specific modification can then be monitored, by coupling to standard downstream assays, such as click chemistry-based POI-labeling and target-occupancy quantification; immunofluorescence or live imaging; RNA-sequencing and real-time quantitative polymerase chain reaction analyses of downstream-transcript modulations. Transient expression of requisite Halo-POI in zebrafish embryos is achieved by messenger RNA injection. Procedures associated with generation of transgenic zebrafish expressing a tissue-specific Halo-POI are also described. The Z-REX experiments can be completed in <1 week using standard techniques. To successfully execute Z-REX, researchers should have basic skills in fish husbandry, imaging and pathway analysis. Experience with protein or proteome manipulation is useful. This Protocol Extension is aimed at helping chemical biologists study precision redox events in a model organism and fish biologists perform redox chemical biology.

Finding a vocation for validation: taking proteomics beyond association and location

First established in the seventies, proteomics, chemoproteomics, and most recently, spatial/proximity-proteomics technologies have empowered researchers with new capabilities to illuminate cellular communication networks that govern sophisticated decision-making processes. With an ever-growing inventory of these advanced proteomics tools, the onus is upon the researchers to understand their individual advantages and limitations, such that we can ensure rigorous implementation and conclusions derived from critical data interpretations backed up by orthogonal series of functional validations. This perspective-based on the authors' experience in applying varied proteomics workflows in complex living models-underlines key book-keeping considerations, comparing and contrasting most-commonly-deployed modern proteomics profiling technologies. We hope this article stimulates thoughts among expert users and equips new-comers with practical knowhow of what has become an indispensable tool in chemical biology, drug discovery, and broader life-science investigations.

Z-REX uncovers a bifurcation in function of Keap1 paralogs

Studying electrophile signaling is marred by difficulties in parsing changes in pathway flux attributable to on-target, vis-à-vis off-target, modifications. By combining bolus dosing, knockdown, and Z-REX-a tool investigating on-target/on-pathway electrophile signaling, we document that electrophile labeling of one zebrafish-Keap1-paralog (zKeap1b) stimulates Nrf2- driven antioxidant response (AR) signaling (like the human-ortholog). Conversely, zKeap1a is a dominant-negative regulator of electrophile-promoted Nrf2-signaling, and itself is nonpermissive for electrophile-induced Nrf2-upregulation. This behavior is recapitulated in human cells: (1) zKeap1b-expressing cells are permissive for augmented AR-signaling through reduced zKeap1b-Nrf2 binding following whole-cell electrophile treatment; (2) zKeap1a-expressing cells are non-permissive for AR-upregulation, as zKeap1a-Nrf2 binding capacity remains unaltered upon whole-cell electrophile exposure; (3) 1:1 ZKeap1a:zKeap1b-co-expressing cells show no Nrf2-release from the Keap1-complex following whole-cell electrophile administration, rendering these cells unable to upregulate AR. We identified a zKeap1a-specific point-mutation (C273I) responsible for zKeap1a's behavior during electrophilic stress. Human-Keap1(C273I), of known diminished Nrf2-regulatory capacity, dominantly muted electrophile-induced Nrf2-signaling. These studies highlight divergent and interdependent electrophile signaling behaviors, despite conserved electrophile sensing.

Role of Protein Damage Inflicted by Dopamine Metabolites in Parkinson's Disease: Evidence, Tools, and Outlook

Dopamine is an important neurotransmitter that plays a critical role in motivational salience and motor coordination. However, dysregulated dopamine metabolism can result in the formation of reactive electrophilic metabolites which generate covalent adducts with proteins. Such protein damage can impair native protein function and lead to neurotoxicity, ultimately contributing to Parkinson's disease etiology. In this Review, the role of dopamine-induced protein damage in Parkinson's disease is discussed, highlighting the novel chemical tools utilized to drive this effort forward. Continued innovation of methodologies which enable detection, quantification, and functional response elucidation of dopamine-derived protein adducts is critical for advancing this field. Work in this area improves foundational knowledge of the molecular mechanisms that contribute to dopamine-mediated Parkinson's disease progression, potentially assisting with future development of therapeutic interventions.

A Ubiquitin-Proteasome Gene Signature for Predicting Prognosis in Patients With Lung Adenocarcinoma

Background: Dysregulation of the ubiquitin-proteasome system (UPS) can lead to instability in the cell cycle and may act as a crucial factor in both tumorigenesis and tumor progression. However, there is no established prognostic signature based on UPS genes (UPSGs) for lung adenocarcinoma (LUAD) despite their value in other cancers.

Methods: We retrospectively evaluated a total of 703 LUAD patients through multivariate Cox and Lasso regression analyses from two datasets, the Cancer Genome Atlas (n = 477) and GSE31210 (n = 226). An independent dataset (GSE50081) containing 128 LUAD samples were used for validation.

Results: An eight-UPSG signature, including ARIH2, FBXO9, KRT8, MYLIP, PSMD2, RNF180, TRIM28, and UBE2V2, was established. Kaplan-Meier survival analysis and time-receiver operating characteristic curves for the training and validation datasets revealed that this risk signature presented with good performance in predicting overall and relapsed-free survival. Based on the signature and its associated clinical features, a nomogram and corresponding web-based calculator for predicting survival were established. Calibration plot and decision curve analyses showed that this model was clinically useful for both the training and validation datasets. Finally, a web-based calculator (https://ostool.shinyapps.io/lungcancer) was built to facilitate convenient clinical application of the signature.

Conclusion: An UPSG based model was developed and validated in this study, which may be useful as a novel prognostic predictor for LUAD.

Renal Ischemia Induces Epigenetic Changes in Apoptotic, Proteolytic, and Mitochondrial Genes in Swine Scattered Tubular-like Cells

BACKGROUND

Scattered tubular-like cells (STCs) are dedifferentiated renal tubular cells endowed with progenitor-like characteristics to repair injured parenchymal cells. STCs may be damaged and rendered ineffective by renal artery stenosis (RAS), but the underlying processes remain unclear. We hypothesized that RAS alters the epigenetic landscape on DNA and the ensuing gene transcriptional profile of swine STCs.

METHODS

CD24+/CD133+ STCs were isolated from pig kidneys after 10 weeks of RAS or sham (n = 3 each) and their whole 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) profiles were examined by 5mC and 5hmC immunoprecipitation sequencing (MeDIP-/hMeDIP-seq, respectively). A subsequent integrated (MeDIP/hMeDIP-seq/mRNA-seq) analysis was performed by comparing all online available gene sets using Gene Set Enrichment Analysis. Apoptosis, proteolysis, and mitochondrial structure and function were subsequently evaluated in vitro.

RESULTS

Differential expression (DE) analysis revealed 239 genes with higher and 236 with lower 5mC levels and 275 genes with higher and 315 with lower 5hmC levels in RAS-STCs compared to Normal-STCs (fold change ≥1.4 or ≤0.7, p ≤ 0.05). Integrated MeDIP-/hMeDIP-seq/mRNA-seq analysis identified several overlapping (DE-5mC/mRNA and DE-5hmC/mRNA levels) genes primarily implicated in apoptosis, proteolysis, and mitochondrial functions. Furthermore, RAS-STCs exhibited decreased apoptosis, mitochondrial matrix density, and ATP production, and increased intracellular amino acid concentration and ubiquitin expression.

CONCLUSIONS

Renal ischemia induces epigenetic changes in apoptosis-, proteolysis-, and mitochondria-related genes, which correlate with alterations in the transcriptomic profile and corresponding function of swine STCs. These observations may contribute to developing novel targeted interventions to preserve the reparative potency of STCs in renal disease.

Hiding in Plain Sight: The Issue of Hidden Variables

Here we discuss "hidden variables", which are typically introduced during an experiment as a consequence of the application of two independent variables together to create a stimulus. With increased sophistication in modern chemical biology tools and related precision interrogation techniques, hidden variables have become integral to many chemical biologists' routine experiments. For instance, they can appear in the use of light-activatable chemical probes (e.g., μMap, T-REX), or stimulus-induced enzyme activation (e.g., APEX). Unfortunately, control experiments assess only how independent variables affect measured outcomes and not the multiple differences between the two independent variables and the twain. We outline ways to account for potential hidden variables in experimental design and data interpretation as a means to aid developers of new methods, particularly those involving light-driven techniques, chemical activation, or biorthogonal chemistries, to better incorporate well-controlled procedures.

Hitting the Bullseye: Endogenous Electrophiles Show Remarkable Nuance in Signaling Regulation

Our bodies produce a host of electrophilic species that can label specific endogenous proteins in cells. The signaling roles of these molecules are under active debate. However, in our opinion, it is becoming increasingly likely that electrophiles can rewire cellular signaling processes at endogenous levels. Attention is turning more to understanding how nuanced electrophile signaling in cells is. In this Perspective, we describe recent work from our laboratory that has started to inform on different levels of context-specific regulation of proteins by electrophiles. We discuss the relevance of these data to the field and to the broader application of electrophile signaling to precision medicine development, beyond the traditional views of their pleiotropic cytotoxic roles.

Function-guided proximity mapping unveils electrophilic-metabolite sensing by proteins not present in their canonical locales

Enzyme-assisted posttranslational modifications (PTMs) constitute a major means of signaling across different cellular compartments. However, how nonenzymatic PTMs-despite their direct relevance to covalent drug development-impinge on cross-compartment signaling remains inaccessible as current target-identification (target-ID) technologies offer limited spatiotemporal resolution, and proximity mapping tools are also not guided by specific, biologically-relevant, ligand chemotypes. Here we establish a quantitative and direct profiling platform (Localis-rex) that ranks responsivity of compartmentalized subproteomes to nonenzymatic PTMs. In a setup that contrasts nucleus- vs. cytoplasm-specific responsivity to reactive-metabolite modification (hydroxynonenylation), ∼40% of the top-enriched protein sensors investigated respond in compartments of nonprimary origin or where the canonical activity of the protein sensor is inoperative. CDK9-a primarily nuclear-localized kinase-was hydroxynonenylated only in the cytoplasm. Site-specific CDK9 hydroxynonenylation-which we identified in untreated cells-drives its nuclear translocation, downregulating RNA-polymerase-II activity, through a mechanism distinct from that of commonly used CDK9 inhibitors. Taken together, this work documents an unmet approach to quantitatively profile and decode localized and context-specific signaling/signal-propagation programs orchestrated by reactive covalent ligands.

Photocaged dicarbonyl probe provides spatiotemporal control over protein glycation

Protein glycation is a disease associated, non-enzymatic, posttranslational modification generated by endogenous dicarbonyl metabolites. Currently, there is a lack of chemical tools capable of studying protein adducts caused by this class of reactive species. Here, we report a chemical biology platform, termed T-DiP (targetable-dicarbonyl precursor), that releases a physiologically relevant dose of bio-orthogonally functionalized dicarbonyl probe upon irradiation with 365 nm light. This approach enables protein glycation to be controlled with spatiotemporal precision within live cells and expands the chemical toolbox needed to elucidate the roles of glycated proteins across various pathologies.

A primer on harnessing non-enzymatic post-translational modifications for drug design

Of the manifold concepts in drug discovery and design, covalent drugs have re-emerged as one of the most promising over the past 20-or so years. All such drugs harness the ability of a covalent bond to drive an interaction between a target biomolecule, typically a protein, and a small molecule. Formation of a covalent bond necessarily prolongs target engagement, opening avenues to targeting shallower binding sites, protein complexes, and other difficult to drug manifolds, amongst other virtues. This opinion piece discusses frameworks around which to develop covalent drugs. Our argument, based on results from our research program on natural electrophile signaling, is that targeting specific residues innately involved in native signaling programs are ideally poised to be targeted by covalent drugs. We outline ways to identify electrophile-sensing residues, and discuss how studying ramifications of innate signaling by endogenous molecules can provide a means to predict drug mechanism and function and assess on- versus off-target behaviors.

Analysis of potential genetic biomarkers and molecular mechanism of smoking-related postmenopausal osteoporosis using weighted gene co-expression network analysis and machine learning

OBJECTIVES

Smoking is a significant independent risk factor for postmenopausal osteoporosis, leading to genome variations in postmenopausal smokers. This study investigates potential biomarkers and molecular mechanisms of smoking-related postmenopausal osteoporosis (SRPO).

MATERIALS AND METHODS

The GSE13850 microarray dataset was downloaded from Gene Expression Omnibus (GEO). Gene modules associated with SRPO were identified using weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) analysis, and pathway and functional enrichment analyses. Feature genes were selected using two machine learning methods: support vector machine-recursive feature elimination (SVM-RFE) and random forest (RF). The diagnostic efficiency of the selected genes was assessed by gene expression analysis and receiver operating characteristic curve.

RESULTS

Eight highly conserved modules were detected in the WGCNA network, and the genes in the module that was strongly correlated with SRPO were used for constructing the PPI network. A total of 113 hub genes were identified in the core network using topological network analysis. Enrichment analysis results showed that hub genes were closely associated with the regulation of RNA transcription and translation, ATPase activity, and immune-related signaling. Six genes (HNRNPC, PFDN2, PSMC5, RPS16, TCEB2, and UBE2V2) were selected as genetic biomarkers for SRPO by integrating the feature selection of SVM-RFE and RF.

CONCLUSION

The present study identified potential genetic biomarkers and provided a novel insight into the underlying molecular mechanism of SRPO.

UBE2V2 Positively Correlates With PD-L1 Expression and Confers Poor Patient Survival in Lung Adenocarcinoma

This research aims to explore the diagnostic and prognostic value of ubiquitin-conjugating enzyme E2 variant 2 (UBE2V2) in lung adenocarcinoma (LUAD). The expression of UBE2V2 in clinical specimens was evaluated by bioinformatics analyses and immunohistochemistry. Bioinformatics analyses relying on the The Cancer Genome Atlas (TCGA) database suggested the elevated UBE2V2 mRNA levels in LUAD in comparison to adjacent normal tissues. Gene set enrichment analyses and gene ontology term enrichment analyses further showed the involvement of UBE2V2 in the modulation of cell cycle and immune associated signaling. The correlation analyses in TCGA LUAD data set revealed the positive correlation between UBE2V2 and CCNE1, CCNE2, CCNA2, CCNB1, CCNB2, cyclin-dependent kinase (CDK)2, CDK4, and CDK1 at the mRNA level. Moreover, UBE2V2 mRNA levels were positively correlated with PD-L1 mRNA levels, the T classification, and poor survival of LUAD patients, and were negatively correlated with type II interferon response. Consistent with the results obtained from TCGA data mining, immunohistochemistry demonstrated that UBE2V2 protein levels were upregulated in LUAD in comparison to normal tissues and were positively associated with T classification. Intriguingly, a positive correlation between UBE2V2 protein levels and PD-L1 expression was also elucidated in clinical samples. Besides, UBE2V2 expression indicated a poor prognosis in LUAD patients. Our study found that UBE2V2 was identified as an independent prognostic indicator for LUAD and might serve as an alternative target for LUAD treatment.

miR-499a inhibits the proliferation and apoptosis of prostate cancer via targeting UBE2V2

BACKGROUND

Prostate cancer is one of the malignant tumors of the urinary system and ranks second among the fatal cancers in men. And with age, the incidence of prostate cancer will increase linearly.

METHODS

In this study, we measured the expression of Ubiquitin Conjugating Enzyme E2 V2 (UBE2V2) in prostate cancer tissues and cell lines by WB and explored the effect of UBE2V2 on the proliferation characteristics of prostate cancer by MTT and colony formation test.

RESULTS

In our research, we found that the UBE2V2 protein level in prostate cancer cell lines was significantly higher than the UBE2V2 protein level in normal prostate cells, and the mRNA expression level did not change significantly compared with normal prostate tissue cells. At the same time, we found that miR-499a combined with UBE2V2 inhibited the expression of UBE2V2 in prostate cancer cells.

CONCLUSIONS

In conclusion, our results indicate that miR-499a inhibits the proliferation of human prostate cancer cells by targeting UBE2V2, which will provide a potential target for the treatment of prostate cancer.

DNA Homeostasis and Senescence: Lessons from the Naked Mole Rat

As we age, our bodies accrue damage in the form of DNA mutations. These mutations lead to the generation of sub-optimal proteins, resulting in inadequate cellular homeostasis and senescence. The build-up of senescent cells negatively affects the local cellular micro-environment and drives ageing associated disease, including neurodegeneration. Therefore, limiting the accumulation of DNA damage is essential for healthy neuronal populations. The naked mole rats (NMR) are from eastern Africa and can live for over three decades in chronically hypoxic environments. Despite their long lifespan, NMRs show little to no biological decline, neurodegeneration, or senescence. Here, we discuss molecular pathways and adaptations that NMRs employ to maintain genome integrity and combat the physiological and pathological decline in organismal function.

An Oculus to Profile and Probe Target Engagement In Vivo: How T-REX Was Born and Its Evolution into G-REX

Here we provide a personal account of innovation and design principles underpinning a method to interrogate precision electrophile signaling that has come to be known as "REX technologies". This Account is framed in the context of trying to improve methods of target mining and understanding of individual target-ligand engagement by a specific natural electrophile and the ramifications of this labeling event in cells and organisms. We start by explaining from a practical standpoint why gleaning such understanding is critical: we are constantly assailed by a battery of electrophilic molecules that exist as a consequence of diet, food preparation, ineluctable endogenous metabolic processes, and potentially disease. The resulting molecules, which are detectable in the body, appear to be able to modify function of specific proteins. Aside from potentially being biologically relevant in their own right, these labeling events are essentially identical to protein-covalent drug interactions. Thus, on what proteins and even in what ways a covalent drug will work can be understood through the eyes of natural electrophiles; extending this logic leads to the postulate that target identification of specific electrophiles can inform on drug design. However, when we entered this field, there was no way to interrogate how a specific labeling event impacted a specific protein in an unperturbed cell. Methods to evaluate stoichiometry of labeling, and even chemospecificity of a specific phenotype were limited. There were further no generally accepted ways to study electrophile signaling that did not hugely disturb physiology.We developed T-REX, a method to study single-protein-specific electrophile engagement, to interrogate how single-protein electrophile labeling shapes pathway flux. Using T-REX, we discovered that labeling of several proteins by a specific electrophile, even at low occupancy, leads to biologically relevant signaling outputs. Further experimentation using T-REX showed that in some instances, single-protein isoforms were electrophile responsive against other isoforms, such as Akt3. Selective electrophile-labeling of Akt3 elicited inhibition of Akt-pathway flux in cells and in zebrafish embryos. Using these data, we rationally designed a molecule to selectively target Akt3. This was a fusion of the naturally derived electrophile and an isoform-nonspecific, reversible Akt inhibitor in phase-II trials, MK-2206. The resulting molecule was a selective inhibitor of Akt3 and was shown to fare better than MK-2206 in breast cancer xenograft mouse models. Recently, we have also developed a means to screen electrophile sensors that is unbiased and uses a precise burst of electrophiles. Using this method, dubbed G-REX, in conjunction with T-REX, we discovered new DNA-damage response upregulation pathways orchestrated by simple natural electrophiles. We thus emphasize how deriving a quantitative understanding of electrophile signaling that is linked to thorough and precise mechanistic studies can open doors to numerous medicinally and biologically relevant insights, from gleaning better understanding of target engagement and target mining to rational design of targeted covalent medicines.

Using mRNA deep sequencing to analyze differentially expressed genes during Panax notoginseng saponin treatment of ischemic stroke

Treatment with Panax notoginseng saponin (PNS) can prevent neurological damage in middle cerebral artery occlusion model rats to promote recovery after a stroke. However, the exact molecular mechanisms are unknown and require further study. In the present study, mRNA sequencing was employed to investigate differential gene expression between model and sham groups, and between model and PNS‑treated groups. Enrichment of gene data was performed using Gene Ontology analysis and the Kyoto Encyclopedia of Genes and Genomes database. Hub genes were identified and networks were constructed using Cytoscape that were further verified by reverse transcription‑quantitative PCR. A total of 1,104 genes of interest were found, which included 690 upregulated and 414 downregulated genes that were identified when the model was compared with the sham group. Additionally, 817 genes of interest, which included 390 upregulated and 427 downregulated genes, were identified when the PNS‑treated group was compared with the model group. There were 303 overlapping genes of interest between the analysis of model to sham groups, and the analysis of model to PNS‑treated groups. The top 10 genes from the 303 aberrantly expressed genes of interest included ubiquitin conjugating enzyme E2 variant 2, small ubiquitin‑related modifier 1, small RNA binding exonuclease protection factor La, Finkel‑Biskis‑Reilly murine sarcoma virus (FBR‑MuSV) ubiquitously expressed, centrosomal protein 290 kDa, DNA‑directed RNA polymerase II subunit K, cullin‑4B, matrin‑3 and vascular endothelial growth factor receptor 2. In conclusion, these genes may be important in the underlying mechanism of PNS treatment in ischemic stroke. Additionally, the present data provided novel insight into the pathogenesis of ischemic stroke.

Getting the Right Grip? How Understanding Electrophile Selectivity Profiles Could Illuminate Our Understanding of Redox Signaling

Significance: Electrophile signaling is coming into focus as a bona fide cell signaling mechanism. The electrophilic regulation occurs typically through a sensing event (i.e., labeling of a protein) and a signaling event (the labeling event having an effect of the proteins activity, association, etc.). Recent Advances: Herein, we focus on the first step of this process, electrophile sensing. Electrophile sensing is typically a deceptively simple reaction between the thiol of a protein cysteine, of which there are around 200,000 in the human proteome, and a Michael acceptor, of which there are numerous flavors, including enals and enones. Recent data overall paint a picture that despite being a simple chemical reaction, electrophile sensing is a discerning process, showing labeling preferences that are often not in line with reactivity of the electrophile. Critical Issues: With a view to trying to decide what brings about highly electrophile-reactive protein cysteines, and how reactive these sensors may be, we discuss aspects of the thermodynamics and kinetics of covalent/noncovalent binding. Data made available by several laboratories indicate that it is likely that specific proteins exhibit highly stereo- and chemoselective electrophile sensing, which we take as good evidence for recognition between the electrophile and the protein before forming a covalent bond. Future Directions: We propose experiments that could help us gain a better and more quantitative understanding of the mechanisms through which sensing comes about. We further extoll the importance of performing more detailed experiments on labeling and trying to standardize the way we assess protein-specific electrophile sensing.

Time to Get Turned on by Chemical Biology

The pressing need for innovation in drug discovery is spurring the emergence of drugs that turn on protein function, as opposed to shutting activity down. Several pharmacophores usher protein target gain-of-function, for instance: PROTACs promote protein target degradation; other drug candidates have been reported to function through dominant-negative inhibition of their target enzyme. Such classes of molecules are typically active at low target occupancy and display numerous advantages relative to canonical inhibitors, whose function is intrinsically tied to achieving, or exceeding a threshold occupancy. However, our ability to generally tap into gain-of-function processes through small molecule interventions is overall in its infancy. Herein, I outline how chemical biology is poised to help us bring this powerful idea to fruition. I further outline means through which gain-of-function events can be identified and harnessed.

Neighborhood watch: tools for defining locale-dependent subproteomes and their contextual signaling activities

Transient associations between numerous organelles-e.g., the endoplasmic reticulum and the mitochondria-forge highly-coordinated, particular environments essential for cross-compartment information flow. Our perspective summarizes chemical-biology tools that have enabled identifying proteins present within these itinerant communities against the bulk proteome, even when a particular protein's presence is fleeting/substoichiometric. However, proteins resident at these ephemeral junctions also experience transitory changes to their interactomes, small-molecule signalomes, and, importantly, functions. Thus, a thorough census of sub-organellar communities necessitates functionally probing context-dependent signaling properties of individual protein-players. Our perspective accordingly further discusses how repurposing of existing tools could allow us to glean a functional understanding of protein-specific signaling activities altered as a result of organelles pulling together. Collectively, our perspective strives to usher new chemical-biology techniques that could, in turn, open doors to modulate functions of specific subproteomes/organellar junctions underlying the nuanced regulatory subsystem broadly termed as contactology.

The mRNA-Binding Protein HuR Is a Kinetically-Privileged Electrophile Sensor

The key mRNA-binding proteins HuR and AUF1 are reported stress sensors in mammals. Intrigued by recent reports of sensitivity of these proteins to the electrophilic lipid prostaglandin A2 and other redox signals, we here examined their sensing abilities to a prototypical redox-linked lipid-derived electrophile, 4-hydroxynonenal (HNE). Leveraging our T-REX electrophile delivery platform, we found that only HuR, and not AUF1, is a kinetically-privileged sensor of HNE in HEK293T cells, and sensing functions through a specific cysteine, C13. Cells depleted of HuR, upon treatment with HNE, manifest unique alterations in cell viability and Nrf2-transcription-factor-driven antioxidant response (AR), which our recent work shows is regulated by HuR at the Nrf2-mRNA level. Mutagenesis studies showed that C13-specific sensing alone is not sufficient to explain HuR-dependent stress responsivities, further highlighting a complex context-dependent layer of Nrf2/AR regulation through HuR.

Electrophile Signaling and Emerging Immuno- and Neuro-modulatory Electrophilic Pharmaceuticals

With a lipid-rich environment and elevated oxygen consumption, the central nervous system (CNS) is subject to intricate regulation by lipid-derived electrophiles (LDEs). Investigations into oxidative damage and chronic LDE generation in neural disorders have spurred the development of tools that can detect and catalog the gamut of LDE-adducted proteins. Despite these advances, deconstructing the precise consequences of individual protein-specific LDE modifications remained largely impossible until recently. In this perspective, we first overview emerging toolsets that can decode electrophile-signaling events in a protein/context-specific manner, and how the accumulating mechanistic insights brought about by these tools have begun to offer new means to modulate pathways relevant to multiple sclerosis (MS). By surveying the latest data surrounding the blockbuster MS drug dimethyl fumarate that functions through LDE-signaling-like mechanisms, we further provide a vision for how chemical biology tools probing electrophile signaling may be leveraged toward novel interventions in CNS disease.

A Hierarchical Machine Learning Model to Discover Gleason Grade-Specific Biomarkers in Prostate Cancer

(1) Background:One of the most common cancers that affect North American men and men worldwide is prostate cancer. The Gleason score is a pathological grading system to examine the potential aggressiveness of the disease in the prostate tissue. Advancements in computing and next-generation sequencing technology now allow us to study the genomic profiles of patients in association with their different Gleason scores more accurately and effectively. (2) Methods: In this study, we used a novel machine learning method to analyse gene expression of prostate tumours with different Gleason scores, and identify potential genetic biomarkers for each Gleason group. We obtained a publicly-available RNA-Seq dataset of a cohort of 104 prostate cancer patients from the National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) repository, and categorised patients based on their Gleason scores to create a hierarchy of disease progression. A hierarchical model with standard classifiers in different Gleason groups, also known as nodes, was developed to identify and predict nodes based on their mRNA or gene expression. In each node, patient samples were analysed via class imbalance and hybrid feature selection techniques to build the prediction model. The outcome from analysis of each node was a set of genes that could differentiate each Gleason group from the remaining groups. To validate the proposed method, the set of identified genes were used to classify a second dataset of 499 prostate cancer patients collected from cBioportal. (3) Results: The overall accuracy of applying this novel method to the first dataset was 93.3%; the method was further validated to have 87% accuracy using the second dataset. This method also identified genes that were not previously reported as potential biomarkers for specific Gleason groups. In particular, PIAS3 was identified as a potential biomarker for Gleason score 4 + 3 = 7, and UBE2V2 for Gleason score 6. (4) Insight: Previous reports show that the genes predicted by this newly proposed method strongly correlate with prostate cancer development and progression. Furthermore, pathway analysis shows that both PIAS3 and UBE2V2 share similar protein interaction pathways, the JAK/STAT signaling process.

miRNAs deregulation in serum of mice is associated with lung cancer related pathway deregulation induced by PM2.5

Ambient fine particulate matter (PM2.5) as an environmental pollution has been associated with the lung cancer. However, the mechanism of epigenetics such as miRNAs deregulation between PM2.5-exposure and lung cancer has not been elucidated clearly. Twenty C57BL/6 mice were divided randomly into 2 groups and exposed to the filtered air (FA) and the concentrated air (CA), respectively. The FA mice were exposed to filtered air in chambers with a high-efficient particulate air filter (HEPA-filter), and the CA mice were exposed to concentration ambient PM2.5. The total duration of exposure was performed 6 h per day from December 1st, 2017 to January 27th, 2018. The mice exposed 900.21 μg/m³ PM2.5 for 6 h per day in CA chamber, which was nearly equaled to 225.05 μg/m³ for 24-h calculatingly. After exposure, the serum miRNAs levels were detected by microarray. Genetic and pathological alterations in lung of mice with/without PM2.5 exposure were detected. 38 differential miRNAs in serum of mice were found after PM2.5 exposure for 8 weeks. Among of them, 13 miRNAs related with lung cancer were consistent in serum and lung of mice. The target genes of 13 deregulated miRNAs including CRK, NR2F2, VIM, RASSF1, CCND2, PRKCA, SIRT1, CDK6, MAP3K7, HIF1A, UBE2V2, ATG10, BAX, E2F1, RASSF5 and CTNNB1, could involve in the pathway of lung cancer developing. Compared with the FA group, the significantly increases of histopathological changes, ROS and DNA damage were observed in lung of mice in CA group. Our study suggested that miRNAs in serum could be identified as candidate biomarkers to predict the lung cancer development during early PM2.5 exposure.

Breaking the Fourth Wall: Modulating Quaternary Associations for Protein Regulation and Drug Discovery

Protein-protein interactions (PPIs) are an effective means to orchestrate intricate biological processes required to sustain life. Approximately 650 000 PPIs underlie the human interactome; thus underscoring its complexity and the manifold signaling outputs altered in response to changes in specific PPIs. This minireview illustrates the growing arsenal of PPI assemblies and offers insights into how these varied PPI regulatory modalities are relevant to customized drug discovery, with a focus on cancer. First, known and emerging PPIs and PPI-targeted drugs of both natural and synthetic origin are categorized. Building on these discussions, the merits of PPI-guided therapeutics over traditional drug design are discussed. Finally, a compare-and-contrast section for different PPI blockers, with gain-of-function PPI interventions, such as PROTACS, is provided.

Regulation of stress signaling pathways by protein lipoxidation

Enzymatic and non-enzymatic oxidation of unsaturated fatty acids gives rise to reactive species that covalently modify nucleophilic residues within redox sensitive protein sensors in a process called lipoxidation. This triggers adaptive signaling pathways that ultimately lead to increased resistance to stress. In this graphical review, we will provide an overview of pathways affected by protein lipoxidation and the key signaling proteins being altered, focusing on the KEAP1-NRF2 and heat shock response pathways. We review the mechanisms by which lipid peroxidation products can serve as second messengers and evoke cellular responses via covalent modification of key sensors of altered cellular environment, ultimately leading to adaptation to stress.

Genie in a bottle: controlled release helps tame natural polypharmacology?

Ability to faithfully report drug-target interactions constitutes a major critical parameter in preclinical/clinical settings. Yet the assessment of target engagement remains challenging, particularly for promiscuous and/or polypharmacologic ligands. Drawing from our improved insights into native electrophile signaling and emerging technologies that profile and interrogate these non-enzyme-assisted signaling subsystems, we posit that 'trained' polypharmocologic covalent inhibitors can be designed. Accumulating evidence indicates that electrophile-modified states at fractional occupancy can alter cell fate. Thus, by understanding sensing preferences and ligandable regions favored by the natural electrophilic signals at individual protein-ligand resolution, we can better evaluate target engagement and develop a function-guided understanding of polypharmacology.

Chemical Biology Gateways to Mapping Location, Association, and Pathway Responsivity

Here we discuss, how by applying chemical concepts to biological problems, methods have been developed to map spatiotemporal regulation of proteins and small-molecule modulation of proteome signaling responses. We outline why chemical-biology platforms are ideal for such purposes. We further discuss strengths and weaknesses of chemical-biology protocols, contrasting them against classical genetic and biochemical approaches. We make these evaluations based on three parameters: occupancy; functional information; and spatial restriction. We demonstrate how the specific choice of chemical reagent and experimental set-up unite to resolve biological problems. Potential improvements/extensions as well as specific controls that in our opinion are often overlooked or employed incorrectly are also considered. Finally, we discuss some of the latest emerging methods to illuminate how chemical-biology innovations provide a gateway toward information hitherto inaccessible by conventional genetic/biochemical means. Finally, we also caution against solely relying on chemical-biology strategies and urge the field to undertake orthogonal validations to ensure robustness of results.

REX technologies for profiling and decoding the electrophile signaling axes mediated by Rosetta Stone proteins

It is now clear that some cysteines on some proteins are highly tuned to react with electrophiles. Based on numerous studies, it is also established that electrophile sensing underpins rewiring of several critical signaling processes. These electrophile-sensing proteins, or privileged first responders (PFRs), are likely critically relevant for drug design. However, identifying PFRs remains a challenging and unsolved problem, despite the development of several high-throughput methods to ID proteins that react with electrophiles. More importantly, we remain unable to rank how different PFRs identified under different conditions relate to one another, in terms of sensing or signaling capacity. Here we evaluate different methods to assay sensing functions of proteins and discuss these methods in the context of developing a "ranking scheme." Based on theoretical and experimental evidence, we propose that T-REX-the only targeted-electrophile delivery tool presently available-is a reliable method to rank PFRs. Finally, we address to what extent electrophile sensing and downstream signaling are correlated. Based on our current data, we observe that such behaviors are indeed correlated. It is our hope that through this manuscript researchers from various arms of the stress signaling fields will focus on developing a quantitative understanding of precision electrophile labeling.

Interrogating Precision Electrophile Signaling

Understanding the targets and signaling roles of reactive electrophilic species (RES) at a specific cellular space and time has long been hampered by the reliance of the field on the bulk administration of excess RES from outside of cells and/or animals. Uncontrolled bolus methods provide limited understanding of target engagement for these individual nonenzymatic RES-modification events. REX technologies [targetable reactive electrophiles and oxidants (T-REX) and its genome-wide variant (G-REX)] were developed as a gateway to address these limitations. These protocols offer a new ability to both profile kinetically privileged sensors (KPSs) of RES at a systems level (G-REX™ profiling) and monitor signaling responses at the sensor protein-of-interest (POI)-specific level (T-REX™ delivery) with high spatiotemporal resolution. REX technologies are compatible with several model systems and are built on a HaloTag-targetable small-molecule photocaged precursor to a native RES.

Proteasome lid bridges mitochondrial stress with Cdc53/Cullin1 NEDDylation status

Cycles of Cdc53/Cullin1 rubylation (a.k.a NEDDylation) protect ubiquitin-E3 SCF (Skp1-Cullin1-F-box protein) complexes from self-destruction and play an important role in mediating the ubiquitination of key protein substrates involved in cell cycle progression, development, and survival. Cul1 rubylation is balanced by the COP9 signalosome (CSN), a multi-subunit derubylase that shows 1:1 paralogy to the 26S proteasome lid. The turnover of SCF substrates and their relevance to various diseases is well studied, yet, the extent by which environmental perturbations influence Cul1 rubylation/derubylation cycles per se is still unclear. In this study, we show that the level of cellular oxidation serves as a molecular switch, determining Cullin1 rubylation/derubylation ratio. We describe a mutant of the proteasome lid subunit, Rpn11 that exhibits accumulated levels of Cullin1-Rub1 conjugates, a characteristic phenotype of csn mutants. By dissecting between distinct phenotypes of rpn11 mutants, proteasome and mitochondria dysfunction, we were able to recognize the high reactive oxygen species (ROS) production during the transition of cells into mitochondrial respiration, as a checkpoint of Cullin1 rubylation in a reversible manner. Thus, the study adds the rubylation cascade to the list of cellular pathways regulated by redox homeostasis.

MicroRNA Expression Profile of Whole Blood Is Altered in Adenovirus-Infected Pneumonia Children

Human adenovirus (Adv) infection is responsible for most community-acquired pneumonia in infants and children, which results in significant morbidity and mortality in children every year. MicroRNAs (miRNAs) are associated with viral replication and host immune response. Knowing the miRNA expression profile will help understand the role of miRNAs in modulating the host response to adenovirus infection and possibly improve the diagnosis of adenovirus-infected pneumonia. In our study, total RNA extracted from whole blood of adenovirus-infected pneumonia children and healthy controls were analyzed by small RNA deep sequencing. Expression profiles of whole blood microRNAs were altered and distinctly different in adenovirus-infected children. The top 3 upregulated miRNA (hsa-miR-127-3p, hsa-miR-493-5p, and hsa-miR-409-3p) were identified in adenovirus-infected children and provided a clear distinction between infected and healthy individuals. Potential host target genes were predicated and validated by qRT-PCR to study the impact of microRNAs on the host genes. Most of the target genes were involved in the MAPK signaling pathway and innate immune response. These highly upregulated microRNAs may have crucial roles in Adv pathogenesis and are potential biomarkers for adenovirus-infected pneumonia.

Proteomics and Beyond: Cell Decision-Making Shaped by Reactive Electrophiles

Revolutionary proteomic strategies have enabled rapid profiling of the cellular targets of electrophilic small molecules. However, precise means to directly interrogate how these individual electrophilic modifications at low occupancy functionally reshape signaling networks have until recently been largely limited. We highlight here new methods that transcend proteomic platforms to forge a quantitative link between protein target-selective engagement and downstream signaling. We focus on recent progress in the study of non-enzyme-assisted signaling mechanisms and crosstalk choreographed by native reactive electrophilic species (RES). Using this as a model, we offer a long-term vision of how these toolsets together with fundamental biochemical knowledge of precision electrophile signaling may be harnessed to assist covalent ligand-target matching and ultimately amend disease-specific signaling dysfunction.

Redox Signaling by Reactive Electrophiles and Oxidants

The concept of cell signaling in the context of nonenzyme-assisted protein modifications by reactive electrophilic and oxidative species, broadly known as redox signaling, is a uniquely complex topic that has been approached from numerous different and multidisciplinary angles. Our Review reflects on five aspects critical for understanding how nature harnesses these noncanonical post-translational modifications to coordinate distinct cellular activities: (1) specific players and their generation, (2) physicochemical properties, (3) mechanisms of action, (4) methods of interrogation, and (5) functional roles in health and disease. Emphasis is primarily placed on the latest progress in the field, but several aspects of classical work likely forgotten/lost are also recollected. For researchers with interests in getting into the field, our Review is anticipated to function as a primer. For the expert, we aim to stimulate thought and discussion about fundamentals of redox signaling mechanisms and nuances of specificity/selectivity and timing in this sophisticated yet fascinating arena at the crossroads of chemistry and biology.

Single-Protein-Specific Redox Targeting in Live Mammalian Cells and C. elegans

T-REX (targetable reactive electrophiles and oxidants) enables electrophile targeting in living systems with high spatiotemporal precision and at single-protein-target resolution. T-REX allows functional consequences of individual electrophile signaling events to be directly linked to on-target modifications. T-REX is accomplished by expressing a HaloTagged protein of interest (POI) and introducing a Halo-targetable bioinert photocaged precursor to a reactive electrophilic signal (RES). Light exposure releases the unfettered RES on demand, enabling precision modification of the POI due to proximity. Using alkyne-functionalized 4-hydroxynonenal (HNE) as a representative RES, this protocol delineates optimized strategies to (1) execute T-REX in live human cells and C. elegans, (2) quantitate the POI's RES-sensitivity by either azido-fluorescent-dye conjugation or (3) enrich using biotin-azide/streptavidin pulldown procedure in both model systems, and (4) identify the site of RES-labeling on the POI using proteomics. Built-in T-REX controls that allow users to directly confirm on-target/on-site specificity of RES-sensing are also described. © 2018 by John Wiley & Sons, Inc.

Cardiovascular Small Heat Shock Protein HSPB7 Is a Kinetically Privileged Reactive Electrophilic Species (RES) Sensor

Small heat shock protein (sHSP)-B7 (HSPB7) is a muscle-specific member of the non-ATP-dependent sHSPs. The precise role of HSPB7 is enigmatic. Here, we disclose that zebrafish Hspb7 is a kinetically privileged sensor that is able to react rapidly with native reactive electrophilic species (RES), when only substoichiometric amounts of RES are available in proximity to Hspb7 expressed in living cells. Among the two Hspb7-cysteines, this RES sensing is fulfilled by a single cysteine (C117). Purification and characterizations in vitro reveal that the rate for RES adduction is among the most efficient reported for protein-cysteines with native carbonyl-based RES. Covalent-ligand binding is accompanied by structural changes (increase in β-sheet-content), based on circular dichroism analysis. Among the two cysteines, only C117 is conserved across vertebrates; we show that the human ortholog is also capable of RES sensing in cells. Furthermore, a cancer-relevant missense mutation reduces this RES-sensing property. This evolutionarily conserved cysteine-biosensor may play a redox-regulatory role in cardioprotection.

Getting the Message? Native Reactive Electrophiles Pass Two Out of Three Thresholds to be Bona Fide Signaling Mediators

Precision cell signaling activities of reactive electrophilic species (RES) are arguably among the most poorly-understood means to transmit biological messages. Latest research implicates native RES to be a chemically-distinct subset of endogenous redox signals that influence cell decision making through non-enzyme-assisted modifications of specific proteins. Yet, fundamental questions remain regarding the role of RES as bona fide second messengers. Here, we lay out three sets of criteria we feel need to be met for RES to be considered as true cellular signals that directly mediate information transfer by modifying "first-responding" sensor proteins. We critically assess the available evidence and define the extent to which each criterion has been fulfilled. Finally, we offer some ideas on the future trajectories of the electrophile signaling field taking inspiration from work that has been done to understand canonical signaling mediators. Also see the video abstract here: https://youtu.be/rG7o0clVP0c.