Oxidative photocatalysis on membranes triggers non-canonical pyroptosis

Intracellular membranes composing organelles of eukaryotes include membrane proteins playing crucial roles in physiological functions. However, a comprehensive understanding of the cellular responses triggered by intracellular membrane-focused oxidative stress remains elusive. Herein, we report an amphiphilic photocatalyst localised in intracellular membranes to damage membrane proteins oxidatively, resulting in non-canonical pyroptosis. Our developed photocatalysis generates hydroxyl radicals and hydrogen peroxides via water oxidation, which is accelerated under hypoxia. Single-molecule magnetic tweezers reveal that photocatalysis-induced oxidation markedly destabilised membrane protein folding. In cell environment, label-free quantification reveals that oxidative damage occurs primarily in membrane proteins related to protein quality control, thereby aggravating mitochondrial and endoplasmic reticulum stress and inducing lytic cell death. Notably, the photocatalysis activates non-canonical inflammasome caspases, resulting in gasdermin D cleavage to its pore-forming fragment and subsequent pyroptosis. These findings suggest that the oxidation of intracellular membrane proteins triggers non-canonical pyroptosis.

Iterative SuFEx approach for sequence-regulated oligosulfates and its extension to periodic copolymers

The synthesis of sequence-regulated oligosulfates has not yet been established due to the difficulties in precise reactivity control. In this work, we report an example of a multi-directional divergent iterative method to furnish oligosulfates based on a chain homologation approach, in which the fluorosulfate unit is regenerated. The oligosulfate sequences are determined by high resolution mass spectrometry of the hydrolyzed fragments, and polysulfate periodic copolymers are synthesized by using oligomeric bisfluorosulfates in a bi-directional fashion. The synthetic utility of this iterative ligation is demonstrated by preparing crosslinked network polymers as synthetic adhesive materials.

Effects of nurse managers' inclusive leadership on nurses' psychological safety and innovative work behavior: The moderating role of collectivism

INTRODUCTION

In the rapidly evolving healthcare landscape, the capacity to foster innovative work behavior among nurses is increasingly important. This study examined the dynamics between inclusive leadership, psychological safety, collectivism, and innovative work behavior among nurses.

DESIGN

The study used a cross-sectional, correlational design.

METHODS

This study utilized data from 730 medical-surgical nurses who provided direct care to patients. Standardized instruments were used to assess key study variables. Statistical analyses, including moderated mediation regressions, were employed to investigate the complex interplay among these variables.

RESULTS

We found a positive association between inclusive leadership and innovative work behavior, and psychological safety mediated this relationship. Collectivism moderated inclusive leadership's direct relationship with psychological safety and its indirect relationship with innovative work behavior. The results revealed that nurses with lower levels of collectivism were more responsive to their managers' inclusive behaviors, strengthening the relation between inclusive leadership, psychological safety, and innovative work behavior.

CONCLUSION

Our findings suggest that promoting inclusive leadership behaviors among nurse managers to create a psychologically safe environment can motivate nurses to engage in innovative work behavior. However, it is also important to understand that the effectiveness of leadership may differ depending on the collectivist values of individual nurses.

CLINICAL RELEVANCE

Nurse managers should adopt inclusive leadership behaviors, such as valuing trust, open communication, and diversity, in order to foster psychological safety and innovative work behavior among nurses.

Direct 18F-Fluorosulfurylation of Phenols and Amines Using an [18F]FSO2+ Transfer Agent Generated In Situ

We report the direct radiofluorosulfurylation method for the synthesis of ¹⁸F-labeled fluorosulfuryl derivatives from phenols and amines using an [¹⁸F]FSO₂⁺ transfer agent generated in situ. Nucleophilic radiofluorination is achieved even in a hydrous organic medium, obviating the need for azeotropic drying and the use of cryptands. This unprecedented, operationally simple isotopic functionalization facilitates the reliable production of potential radiotracers for positron emission tomography, rendering facile access to SuFEx radiochemistry.

Microphysiological system recapitulating the pathophysiology of adipose tissue in obesity

A growing body of evidence has indicated that white adipose tissue (AT) remodeling is a major trigger for obesity-associated metabolic complications. However, the scarcity of translational models is an obstacle to the development of medicines that act on adipose restoration. Here, we describe a microphysiological system (MPS) that emulates the unique features of reprogrammed AT as a new in vitro tool for studying AT pathophysiology in obesity. The AT MPS contained mature adipocytes embedded in an extracellular matrix (ECM) hydrogel interfaced with AT microvascular endothelium, which was constantly perfused with fresh media. The unique biochemical signals due to the remodeled ECM in obesity were recapitulated using a decellularized AT ECM (AT dECM) hydrogel, which preserves the features of altered ECM composition in obesity. The mature adipocytes embedded in the AT dECM hydrogel maintained their function and morphology for a week without dedifferentiation. Using the AT MPS, we successfully modeled inflammation-induced AT microvascular dysfunction, the recruitment of immune cells due to the upregulation of cell adhesion molecules, and higher cancer cell adhesion as an indicator of metastasis, which are observed in obese individuals. The AT MPS may therefore represent a promising platform for understanding the dynamic cellular interplay in obesity-induced AT remodeling and validating the efficacy of drugs targeting AT in obesity. STATEMENT OF SIGNIFICANCE: The lack of translational in vitro white adipose tissue (AT) models is one of the main obstacles for understanding the obesity-induced reprogramming and the development of medicines. We report herein the AT microphysiological system (MPS), which recapitulates obesity and normal conditions and yields cell- and AT dECM-derived signals, thereby allowing accurate comparative in vitro analyses. Using the AT MPS, we successfully modeled reprogrammed AT in obesity conditions, including inflammation-induced AT vascular dysfunction, the recruitment of immune cells, and higher cancer cell metastasis, which are observed in obese individuals. Our proposed adipose tissue model providing physiological relevance and complexity may therefore enhance the understanding of obesity-associated disorders and be used to investigate their underlying molecular mechanisms to develop pharmacologic treatment strategies.

GPR143 controls ESCRT-dependent exosome biogenesis and promotes cancer metastasis

Exosomes transport a variety of macromolecules and modulate intercellular communication in physiology and disease. However, the regulation mechanisms that determine exosome contents during exosome biogenesis remain poorly understood. Here, we find that GPR143, an atypical GPCR, controls the endosomal sorting complex required for the transport (ESCRT)-dependent exosome biogenesis pathway. GPR143 interacts with HRS (an ESCRT-0 Subunit) and promotes its association to cargo proteins, such as EGFR, which subsequently enables selective protein sorting into intraluminal vesicles (ILVs) in multivesicular bodies (MVBs). GPR143 is elevated in multiple cancers, and quantitative proteomic and RNA profiling of exosomes in human cancer cell lines showed that the GPR143-ESCRT pathway promotes secretion of exosomes that carry unique cargo, including integrins signaling proteins. Through gain- and loss-of-function studies in mice, we show that GPR143 promotes metastasis by secreting exosomes and increasing cancer cell motility/invasion through the integrin/FAK/Src pathway. These findings provide a mechanism for regulating the exosomal proteome and demonstrate its ability to promote cancer cell motility.

Identification of proteomic landscape of drug-binding proteins in live cells by proximity-dependent target ID

Direct identification of the proteins targeted by small molecules can provide clues for disease diagnosis, prevention, and drug development. Despite concentrated attempts, there are still technical limitations associated with the elucidation of direct interactors. Herein, we report a target-ID system called proximity-based compound-binding protein identification (PROCID), which combines our direct analysis workflow of proximity-labeled proteins (Spot-ID) with the HaloTag system to efficiently identify the dynamic proteomic landscape of drug-binding proteins. We successfully identified well-known dasatinib-binding proteins (ABL1, ABL2) and confirmed the unapproved dasatinib-binding kinases (e.g., BTK and CSK) in a live chronic myeloid leukemia cell line. PROCID also identified the DNA helicase protein SMARCA2 as a dasatinib-binding protein, and the ATPase domain was confirmed to be the binding site of dasatinib using a proximity ligation assay (PLA) and in cellulo biotinylation assay. PROCID thus provides a robust method to identify unknown drug-interacting proteins in live cells that expedites the mode of action of the drug.

Effect of early hysterectomy on a risk of incident cardiovascular disease in women: a nationwide population-based cohort study

Aim

Women who inevitably underwent surgical hysterectomy before natural menopause may have an earlier increase in hematocrit and storage iron than women who continue menstruation, thereby increasing the risk of cardiovascular disease (CVD) early. We aimed to evaluate the association of women with hysterectomy vs. without hysterectomy before their 50s with the risk of incident CVD.

Methods

This was a retrospective-cohort study, 135,575 women aged 40 to 50 years in 2011–2014 were extracted from the Korean Health Insurance Review and Assessment Service data and after propensity score matching, 55,539 pairs were included in hysterectomy and non-hysterectomy group respectively. The primary endpoint was major adverse cardiac and cerebrovascular events (MACCE), a composite of cardiovascular death, myocardial infarction (MI), stroke, and coronary artery revascularization.

Results

After adjustment for confounding factors, hysterectomy group had an increased risk of MACCE compared with non-hysterectomy group (hazard ratio [HR], 1.25; 95% confidence interval [CI], 1.09–1.44). Regarding individual outcomes, cardiovascular death, MI, and coronary revascularization were comparable between the groups, whereas, the risk of stroke was significantly higher in hysterectomy group than non-hysterectomy group (HR, 1.31; 95% CI, 1.12–1.53). Even after excluding women who underwent oophorectomy, hysterectomy group had a higher risk of MACCE than non-hysterectomy group (HR, 1.24; 95% CI 1.06–1.44).

Conclusions

Early surgical menopause due to hysterectomy, not hormonal menopause, was associated with an increased risk for a composite of CVD, especially stroke. This suggest that the role of “uterus” as well as sex hormones may be important for the sharp increase in the risk of CVD in women after menopause.

Funding Acknowledgement

Type of funding sources: None.

Optimal strategy for antiplatelet therapy after endovascular revascularization in patients with lower extremity artery disease

Background

The duration of antiplatelet therapy after endovascular revascularization in patients with lower extremity artery disease (LEAD) has not been well established. This study aimed to evaluate the clinical outcome according to the duration of dual antiplatelet therapy (DAPT) in real practice.

Methods

From April 2009 to June 2019, 376 patients with LEAD underwent successful endovascular revascularization. After the procedure, the received single antiplatelet therapy (SAPT) or DAPT of various durations were classified into two groups (SAPT or DAPT <6 months vs. DAPT ≥6 months). The primary outcomes were major adverse cardiovascular events (MACEs) and major adverse limb events (MALEs). The safety outcome was moderate-to-severe bleeding according to the Global Use of Strategies to Open Occluded Arteries (GUSTO) criteria.

Results

Over the 40-month follow-up period, MACE occurred less frequently in the DAPT ≥6 months group than that in the SAPT or DAPT <6 months group (12.4% vs. 23.8%; hazard ratio [HR]: 0.56; 95% confidence interval [CI]: 0.35–0.89; p=0.014) after inverse probability-weighted adjustment and propensity-score matching analysis (HR: 0.55, 95% CI; 0.30–0.99, p=0.048). The incidence of MALE did not show significant difference between the two groups (DAPT ≥6 months group: 17.1% vs. SAPT or DAPT <6 months group: 13.1%; HR: 1.05; 95% CI: 0.62–1.78; p=0.846). A significant difference between the DAPT ≥6 months group and the SAPT or DAPT <6 months group was not observed regarding the incidence of moderate-to-severe GUSTO bleeding.

Conclusions

In patients with LEAD, DAPT for ≥6 months after endovascular revascularization was associated with a lower incidence of MACE.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Research Foundation of Korea (NRF) grant funded by the government of Korea (MSIT) (No. 2019R1G1A1100442).

The impact of statin treatment intensity after endovascular revascularization for lower extremity peripheral artery disease

Purpose

There are few Asian studies on the clinical impact of statin intensity on clinical outcomes in patients with peripheral artery disease (PAD). This study investigated the clinical impact of statin intensity in patients with PAD after endovascular revascularization.

Material and methods

From April 2009 to June 2019, 376 patients with lower extremity PAD treated with endovascular revascularization were enrolled. They were classified into three groups according to statin intensity: no-statin, low-to-moderate intensity (LMI), and high-intensity (HI) groups. The primary outcomes were major adverse cardiovascular events (MACE) and major adverse limb events (MALE).

Results

During the 40-month follow-up, MACE occurred less in the HI and LMI groups than the no-statin group (11.4% vs. 16.0% vs. 39%, p<0.001). In the adjusted Cox models, the HI group had the lowest MACE (hazard ratio [HR]: 0.347; 95% confidence interval [CI] 0.144–0.834; p=0.018) and MALE (HR: 0.344; 95% CI 0.120–0.989, p=0.048), while the LMI group had fewer MACE (HR: 0.319; 95% CI 0.169–0.604, p=0.048) than the no-statin group. HI therapy was associated with better outcomes in terms of MALE (HR: 0.377; 95% CI: 0.208–0.684; p=0.001) and repeat revascularization (HR: 0.449; 95% CI: 0.243–0.830; p=0.011) than the LMI group after the inverse probability treatment weighting analysis.

Conclusions

HI and LMI statin use is associated with a significant reduction of MACE than no statin use. Regarding MALE, HI statin use was associated with better outcomes than no statin or LMI statin use.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2019R1G1A1100442).

Inositol polyphosphate multikinase physically binds to the SWI/SNF complex and modulates BRG1 occupancy in mouse embryonic stem cells

Inositol polyphosphate multikinase (IPMK), a key enzyme in inositol polyphosphate (IP) metabolism, is a pleiotropic signaling factor involved in major biological events, including transcriptional control. In the yeast, IPMK and its IP products promote the activity of the chromatin remodeling complex SWI/SNF, which plays a critical role in gene expression by regulating chromatin accessibility. However, the direct link between IPMK and chromatin remodelers remains unclear, raising the question of how IPMK contributes to transcriptional regulation in mammals. By employing unbiased screening approaches and in vivo/in vitro immunoprecipitation, here we demonstrate that mammalian IPMK physically interacts with the SWI/SNF complex by directly binding to SMARCB1, BRG1, and SMARCC1. Furthermore, we identified the specific domains required for IPMK-SMARCB1 binding. Notably, using CUT&RUN and ATAC-seq assays, we discovered that IPMK co-localizes with BRG1 and regulates BRG1 localization as well as BRG1-mediated chromatin accessibility in a genome-wide manner in mouse embryonic stem cells. Together, these findings show that IPMK regulates the promoter targeting of the SWI/SNF complex, thereby contributing to SWI/SNF-meditated chromatin accessibility, transcription, and differentiation in mouse embryonic stem cells.

Rapid access to polycyclic N-heteroarenes from unactivated, simple azines via a base-promoted Minisci-type annulation

Conventional synthetic methods to yield polycyclic heteroarenes have largely relied on metal-mediated arylation reactions requiring pre-functionalised substrates. However, the functionalisation of unactivated azines has been restricted because of their intrinsic low reactivity. Herein, we report a transition-metal-free, radical relay π-extension approach to produce N-doped polycyclic aromatic compounds directly from simple azines and cyclic iodonium salts. Mechanistic and electron paramagnetic resonance studies provide evidence for the in situ generation of organic electron donors, while chemical trapping and electrochemical experiments implicate an iodanyl radical intermediate serving as a formal biaryl radical equivalent. This intermediate, formed by one-electron reduction of the cyclic iodonium salt, acts as the key intermediate driving the Minisci-type arylation reaction. The synthetic utility of this radical-based annulative π-extension method is highlighted by the preparation of an N-doped heptacyclic nanographene fragment through fourfold C–H arylation.

The functionalisation of unactivated azines has been restricted because of their intrinsic low reactivity. Here the authors show a transition-metal-free, radical relay π-extension approach to produce N-doped polycyclic aromatic compounds directly from simple azines and cyclic iodonium salts.

Valosin-containing protein (VCP) regulates the stability of fused in sarcoma (FUS) granules in cells by changing ATP concentrations

Fused in sarcoma (FUS), a DNA/RNA-binding protein, undergoes liquid-liquid phase separation to form granules in cells. Aberrant FUS granulation is associated with neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. We found that FUS granules contain a multifunctional AAA ATPase, valosin-containing protein (VCP), which is known as a key regulator of protein degradation. FUS granule stability depends on ATP concentrations in cells. VCP ATPase changes the FUS granule stability time-dependently by consuming ATP to reduce its concentrations in the granules: VCPs in de novo FUS granules stabilize the granules, while long-lasting VCP colocalization destabilizes the granules. The proteolysis-promoting function of VCP may subsequently dissolve the unstabilized granules. We propose that VCP colocalized to the FUS granules acts as a timer to limit the residence time of the granules in cells.

Kap1 Regulates the Stability of Lin28A in Embryonic Stem Cells

Lin28A is an RNA-binding protein that controls mammalian development and maintenance of the pluripotency of embryonic stem cells (ESCs) via regulating the processing of the microRNA let-7. Lin28A is highly expressed in ESCs, and ectopic expression of this protein facilitates reprogramming of somatic cells to induced pluripotent stem cells. However, the mechanisms underlying the post-translational regulation of Lin28A protein stability in ESCs remain unclear. In the present study, we identified Kap1 (KRAB-associated protein 1) as a novel Lin28A-binding protein using affinity purification and mass spectrometry. Kap1 specifically interacted with the N-terminal region of Lin28A through its coiled-coil domain. Kap1 overexpression significantly attenuated Lin28A ubiquitination and increased its stability. However, small interfering RNA-mediated knockdown of Kap1 promoted the ubiquitination of Lin28A, leading to its proteasomal degradation. Trim71, an E3 ubiquitin ligase, induced Lin28A degradation and Kap1 knockdown accelerated the Trim71-dependent degradation of Lin28A. Mutation of the lysine 177 residue of Lin28A to arginine abrogated the ubiquitination and degradation of Lin28A which were accelerated by Kap1 silencing. Moreover, Kap1 overexpression led to the accumulation of Lin28A in the cytoplasm, but not in the nucleus, and reduced the levels of let-7 subtypes. These results suggest that Kap1 plays a key role in regulation of the stability of Lin28A by modulating the Trim71-mediated ubiquitination and subsequent degradation of Lin28A, thus playing a pivotal role in the regulation of ESC self-renewal and pluripotency.

A chemical tool for blue light-inducible proximity photo-crosslinking in live cells

We developed a proximity photo-crosslinking method (Spotlight) with a 4-azido-N-ethyl-1,8-naphthalimide (AzNP) moiety that can be converted to reactive aryl nitrene species using ambient blue light-emitting diode light. Using an AzNP-conjugated HaloTag ligand (VL1), blue light-induced photo-crosslinked products of various HaloTag-conjugated proteins of interest were detected in subcellular spaces in live cells. Chemical or heat stress-induced dynamic changes in the proteome were also detected, and photo-crosslinking in the mouse brain tissue was enabled. Using Spotlight, we further identified the host interactome of SARS-CoV-2 nucleocapsid (N) protein, which is essential for viral genome assembly. Mass analysis of the VL1-crosslinked product of N-HaloTag in HEK293T cells showed that RNA-binding proteins in stress granules were exclusively enriched in the cross-linked samples. These results tell that our method can reveal the interactome of protein of interest within a short distance in live cells.

WNT11 is a direct target of early growth response protein 1

WNT11 is a member of the non-canonical Wnt family and plays a crucial role in tumor progression. However, the regulatory mechanisms underlying WNT11 expression are unclear. Tumor necrosis factor-alpha (TNFα) is a major inflammatory cytokine produced in the tumor microenvironment and contributes to processes associated with tumor progression, such as tumor invasion and metastasis. By using site-directed mutagenesis and introducing a serial deletion in the 5'-regulatory region of WNT11, we observed that TNFα activates the early growth response 1 (EGR1)-binding sequence (EBS) in the proximal region of WNT11 and that the transcription factor EGR1 is necessary for the TNFα-induced transcription of WNT11. EGR1 bound directly to the EBSs within the proximal 5'-regulatory region of WNT11 and ectopic expression of EGR1 stimulated WNT11 promoter activity, whereas the knockdown of EGR1 expression by RNA interference reduced TNFα-induced WNT11 expression in T47D breast cancer cells. We also observed that mitogen-activated protein kinases (MAPK), extracellular signalregulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 kinase mediated TNFα-induced transcription of WNT11 via EGR1. Our results suggest that EGR1 directly targets WNT11 in response to TNFα stimulation in breast cancer cells. [BMB Reports 2020; 53(12): 628-633].

Nickelocene as an Air- and Moisture-Tolerant Precatalyst in the Regioselective Synthesis of Multisubstituted Pyridines

Ni(COD)₂-catalyzed cycloaddition reactions to access pyridines have been extensively studied. However, this catalyst typically requires drying procedures and inert-atmosphere techniques for the reactions. Herein, we report operationally simple nickel(0) catalysis to access substituted pyridines from various nitriles and 1,6-diynes without the aid of air-free techniques. The Ni-Xantphos-based catalytic manifold is tolerant to air, moisture, and heat while promoting the [2 + 2 + 2] cycloaddition reactions with high reaction yields and broad substrate scope. In addition, we disclose that not only the steric effect but also the frontier molecular orbital interactions can play a critical role in determining the regiochemical outcome of nickel-catalyzed [2 + 2 + 2] cycloaddition for the synthesis of substituted pyridines.

Late-Stage 18F/19F Isotopic Exchange for the Synthesis of 18F-Labeled Sulfamoyl Fluorides

Synthesis of sulfamoyl [¹⁸F]fluorides has been a challenging topic owing to the inefficient nucleophilic radiofluorination of sulfamoyl derivatives. Herein, we report an ¹⁸F/¹⁹F isotopic exchange approach to synthesize various sulfamoyl [¹⁸F]fluorides, otherwise inaccessible via direct synthesis from amines, with high radiochemical yields up to 97% (30 examples). This late-stage labeling protocol offers an efficient route to yield functionalized molecules by diversifying the chemical library possessing sulfamoyl functionalities through nucleophilic ¹⁸F incorporation within nitrogen-containing sulfur(VI) frameworks.

LONP1 and ClpP cooperatively regulate mitochondrial proteostasis for cancer cell survival

Mitochondrial proteases are key components in mitochondrial stress responses that maintain proteostasis and mitochondrial integrity in harsh environmental conditions, which leads to the acquisition of aggressive phenotypes, including chemoresistance and metastasis. However, the molecular mechanisms and exact role of mitochondrial proteases in cancer remain largely unexplored. Here, we identified functional crosstalk between LONP1 and ClpP, which are two mitochondrial matrix proteases that cooperate to attenuate proteotoxic stress and protect mitochondrial functions for cancer cell survival. LONP1 and ClpP genes closely localized on chromosome 19 and were co-expressed at high levels in most human cancers. Depletion of both genes synergistically attenuated cancer cell growth and induced cell death due to impaired mitochondrial functions and increased oxidative stress. Using mitochondrial matrix proteomic analysis with an engineered peroxidase (APEX)-mediated proximity biotinylation method, we identified the specific target substrates of these proteases, which were crucial components of mitochondrial functions, including oxidative phosphorylation, the TCA cycle, and amino acid and lipid metabolism. Furthermore, we found that LONP1 and ClpP shared many substrates, including serine hydroxymethyltransferase 2 (SHMT2). Inhibition of both LONP1 and ClpP additively increased the amount of unfolded SHMT2 protein and enhanced sensitivity to SHMT2 inhibitor, resulting in significantly reduced cell growth and increased cell death under metabolic stress. Additionally, prostate cancer patients with higher LONP1 and ClpP expression exhibited poorer survival. These results suggest that interventions targeting the mitochondrial proteostasis network via LONP1 and ClpP could be potential therapeutic strategies for cancer.

ERRγ suppression by Sirt6 alleviates cholestatic liver injury and fibrosis

Orphan nuclear receptor estrogen-related receptor γ (ERRγ) stimulates bile acid production; however, the role and the regulatory mechanism of ERRγ in cholestatic liver disease are largely unknown. This study identifies that Sirt6 is a deacetylase of ERRγ and suggests a potentially novel mechanism by which Sirt6 activation alleviates cholestatic liver damage and fibrosis through regulating ERRγ. We observed that hepatic expression of Sirt6 is repressed, whereas hepatic expression of ERRγ is upregulated in murine cholestasis models. Hepatocyte-specific Sirt6-KO mice were more severely injured after a bile duct ligation (BDL) than WT mice, and adenoviral reexpression of Sirt6 reversed liver damage and fibrosis as demonstrated by biochemical and histological analyses. Mechanistically, Sirt6 deacetylated ERRγ, thereby destabilizing ERRγ and inhibiting its transcriptional activity. Elimination of hepatic ERRγ using Ad-shERRγ abolished the deleterious effects of Sirt6 deficiency, whereas ERRγ overexpression aggravated cholestatic liver injury. Administration of a Sirt6 deacetylase activator prevented BDL-induced liver damage and fibrosis. In patients with cholestasis, Sirt6 expression was decreased, whereas total ERRγ and acetylated ERRγ levels were increased, confirming negative regulation of ERRγ by Sirt6. Thus, Sirt6 activation represents a potentially novel therapeutic strategy for treating cholestatic liver injury.

Sirt6 activation alleviates cholestatic liver damage and fibrosis in murine cholestasis models by deacetylation of ERRγ.

Synthesis of 18F-Labeled Aryl Fluorosulfates via Nucleophilic Radiofluorination

Sulfuryl fluoride gas is a key reagent for SO₂F transfer. However, conventional SO₂F transfer reactions have limited ¹⁸F-radiochemistry translation, due to the inaccessibility of gaseous [¹⁸F]SO₂F₂. Herein, we report the first SO₂F₂-free synthesis of aryl [¹⁸F]fluorosulfates from both phenolic and isolated aryl imidazylate precursors with cyclotron-produced ¹⁸F^-. The radiochemical yields ranged from moderate to good with excellent functional group tolerance. The reliability of our approach was validated by the automated radiosynthesis of 4-acetamidophenyl [¹⁸F]fluorosulfate.

The structure of human EXD2 reveals a chimeric 3' to 5' exonuclease domain that discriminates substrates via metal coordination

EXD2 (3′-5′ exonuclease domain-containing protein 2) is an essential protein with a conserved DEDDy superfamily 3′-5′ exonuclease domain. Recent research suggests that EXD2 has two potential functions: as a component of the DNA double-strand break repair machinery and as a ribonuclease for the regulation of mitochondrial translation. Herein, electron microscope imaging analysis and proximity labeling revealed that EXD2 is anchored to the mitochondrial outer membrane through a conserved N-terminal transmembrane domain, while the C-terminal region is cytosolic. Crystal structures of the exonuclease domain in complex with Mn²⁺/Mg²⁺ revealed a domain-swapped dimer in which the central α5−α7 helices are mutually crossed over, resulting in chimeric active sites. Additionally, the C-terminal segments absent in other DnaQ family exonucleases enclose the central chimeric active sites. Combined structural and biochemical analyses demonstrated that the unusual dimeric organization stabilizes the active site, facilitates discrimination between DNA and RNA substrates based on divalent cation coordination and generates a positively charged groove that binds substrates.

Androgen-induced expression of DRP1 regulates mitochondrial metabolic reprogramming in prostate cancer

Androgen receptor (AR) signaling plays a central role in metabolic reprogramming for prostate cancer (PCa) growth and progression. Mitochondria are metabolic powerhouses of the cell and support several hallmarks of cancer. However, the molecular links between AR signaling and the mitochondria that support the metabolic demands of PCa cells are poorly understood. Here, we demonstrate increased levels of dynamin-related protein 1 (DRP1), a mitochondrial fission mediator, in androgen-sensitive and castration-resistant AR-driven PCa. AR signaling upregulates DRP1 to form the VDAC-MPC2 complex, increases pyruvate transport into mitochondria, and supports mitochondrial metabolism, including oxidative phosphorylation and lipogenesis. DRP1 inhibition activates the cellular metabolic stress response, which involves AMPK phosphorylation, induction of autophagy, and the ER unfolded protein response, and attenuates androgen-induced proliferation. Additionally, DRP1 expression facilitates PCa cell survival under diverse metabolic stress conditions, including hypoxia and oxidative stress. Moreover, we found that increased DRP1 expression was indicative of poor prognosis in patients with castration-resistant PCa. Collectively, our findings link androgen signaling-mediated mitochondrial dynamics to metabolic reprogramming; moreover, they have important implications for understanding PCa progression.

Annulative π-Extension of Unactivated Benzene Derivatives through Nondirected C-H Arylation

Annulative π-extension chemistry provides a concise synthetic route to polycyclic arenes. Herein, we disclose a nondirected annulation approach of unactivated simple arenes. The palladium-catalyzed 2-fold C-H arylation event facilitates tandem C-C linkage relays to furnish fully benzenoid triphenylene frameworks using cyclic diaryliodonium salts. The inseparable regioisomeric mixture of 1- and 2-methyltriphenylenes is identified by the combined analysis of ion mobility-mass spectrometry, gas-phase infrared spectroscopy, and molecular simulation studies.

TonEBP Regulates PCNA Polyubiquitination in Response to DNA Damage through Interaction with SHPRH and USP1

Polyubiquitination of proliferating cell nuclear antigen (PCNA) regulates the error-free template-switching mechanism for the bypass of DNA lesions during DNA replication. PCNA polyubiquitination is critical for the maintenance of genomic integrity; however, the underlying mechanism is poorly understood. Here, we demonstrate that tonicity-responsive enhancer-binding protein (TonEBP) regulates PCNA polyubiquitination in response to DNA damage. TonEBP was recruited to DNA damage sites with bulky adducts and sequentially recruited E3 ubiquitin ligase SHPRH, followed by deubiquitinase USP1, to DNA damage sites, in correlation with the dynamics of PCNA polyubiquitination. Similarly, TonEBP was found to be required for replication fork protection in response to DNA damage. The Rel-homology domain of TonEBP, which encircles DNA, was essential for the interaction with SHPRH and USP1, PCNA polyubiquitination, and cell survival after DNA damage. The present findings suggest that TonEBP is an upstream regulator of PCNA polyubiquitination and of the DNA damage bypass pathway.

Distinct phosphorylation and dephosphorylation dynamics of protein arginine kinases revealed by fluorescent activity probes

Protein arginine (Arg) phosphorylation regulates stress responses and virulence in bacteria. With fluorescent activity probes, we show that McsB, a protein Arg kinase, can dephosphorylate phosphoarginine (pArg) residues to produce ATP from ADP, implicating the dynamic control of protein pArg levels by the kinase even without a phosphatase.

Specific Fluorescent Probe for Protein Histidine Phosphatase Activity

Protein histidine phosphorylation plays a vital role in cell signaling and metabolic processes, and phosphohistidine (pHis) phosphatases such as protein histidine phosphatase 1 (PHPT1) and LHPP have been linked to cancer and diabetes, making them novel drug targets and biomarkers. Unlike the case for other classes of phosphatases, further studies of PHPT1 and other pHis phosphatases have been hampered by the lack of specific activity assays in complex biological mixtures. Previous methods relying on radiolabeling are hazardous and technically laborious, and small-molecule phosphatase probes are not selective toward pHis phosphatases. To address these issues, we herein report a fluorescent probe based on chelation-enhanced fluorescence (CHEF) to continuously measure the pHis phosphatase activity of PHPT1. Our probe exhibited excellent sensitivity and specificity toward PHPT1, enabling the first specific measurement of PHPT1 activity in cell lysates. Using this probe, we also obtained more physiologically relevant kinetic parameters of PHPT1, overcoming the limitations of previously used methods.

Direct Identification of Biotinylated Proteins from Proximity Labeling (Spot-BioID)

Recently, proximity labeling has been developed to map spatially localized proteomes in live cells. Usually, these methods employ enzymatic biotinylation of the proximal proteins with reactive biotin species. The labeled proteins may contain biotinylated modifications, which can be enriched by streptavidin beads through affinity purification. However, during the bead enrichment process, unlabeled proteins can be enriched to have specific binding affinity toward the biotinylated proteins or high binding affinity to the bead surface. If the unlabeled proteins remain attached to the beads after washing and are analyzed by mass spectrometry (MS) using the conventional workflow for the unlabeled peptidome, they would appear as proximal proteins in the targeted space. However, the unlabeled proteins, including the specific interaction partners of the biotinylated proteins, are false positives for proximity labeling. Including the unlabeled proteome in the identification list for proximity labeling does not provide a clear picture of the local proteome in the targeted space. This chapter is a detailed protocol of the first direct identification method (Spot-BioID) for identifying biotin-labeled proteomes of promiscuous biotin ligase (pBirA) labeling.

The Cytotoxic Necrotizing Factor of Yersinia pseudotuberculosis (CNFy) is Carried on Extracellular Membrane Vesicles to Host Cells

In this study we show Yersinia pseudotuberculosis secretes membrane vesicles (MVs) that contain different proteins and virulence factors depending on the strain. Although MVs from Y. pseudotuberculosis YPIII and ATCC 29833 had many proteins in common (68.8% of all the proteins identified), those located in the outer membrane fraction differed significantly. For instance, the MVs from Y. pseudotuberculosis YPIII harbored numerous Yersinia outer proteins (Yops) while they were absent in the ATCC 29833 MVs. Another virulence factor found solely in the YPIII MVs was the cytotoxic necrotizing factor (CNFy), a toxin that leads to multinucleation of host cells. The ability of YPIII MVs to transport this toxin and its activity to host cells was verified using HeLa cells, which responded in a dose-dependent manner; nearly 70% of the culture was multinucleated after addition of 5 µg/ml of the purified YPIII MVs. In contrast, less than 10% were multinucleated when the ATCC 29833 MVs were added. Semi-quantification of CNFy within the YPIII MVs found this toxin is present at concentrations of 5 ~ 10 ng per µg of total MV protein, a concentration that accounts for the cellular responses seen.

Netrin-1/DCC-mediated PLCγ1 activation is required for axon guidance and brain structure development

Coordinated expression of guidance molecules and their signal transduction are critical for correct brain wiring. Previous studies have shown that phospholipase C gamma1 (PLCγ1), a signal transducer of receptor tyrosine kinases, plays a specific role in the regulation of neuronal cell morphology and motility in vitro However, several questions remain regarding the extracellular stimulus that triggers PLCγ1 signaling and the exact role PLCγ1 plays in nervous system development. Here, we demonstrate that PLCγ1 mediates axonal guidance through a netrin-1/deleted in colorectal cancer (DCC) complex. Netrin-1/DCC activates PLCγ1 through Src kinase to induce actin cytoskeleton rearrangement. Neuronal progenitor-specific knockout of Plcg1 in mice causes axon guidance defects in the dorsal part of the mesencephalon during embryogenesis. Adult Plcg1-deficient mice exhibit structural alterations in the corpus callosum, substantia innominata, and olfactory tubercle. These results suggest that PLCγ1 plays an important role in the correct development of white matter structure by mediating netrin-1/DCC signaling.

Identification of a novel angiogenic peptide from periostin

Angiogenic peptides have therapeutic potential for the treatment of chronic ischemic diseases. Periostin, an extracellular matrix protein expressed in injured tissues, promotes angiogenesis and tissue repair. We previously reported that in vivo administration of both recombinant full-length protein and the first FAS I domain of periostin alleviated peripheral artery occlusive disease by stimulating the migration of humane endothelial colony forming cells (ECFCs) and subsequent angiogenesis. In the present study, we ascertained the peptide sequence responsible for the periostin-induced angiogenesis. By serial deletion mapping of the first FAS I domain, we identified a peptide sequence (amino acids 142–151) of periostin for stimulation of chemotactic migration, adhesion, proliferation and endothelial tube formation of human ECFCs in vitro. Chemotactic migration of ECFCs induced by the periostin peptide was blocked by pre-incubation with an anti-β5 integrin neutralizing antibody. Treatment of ECFCs with the periostin peptide led to phosphorylation of both AKT and ERK, and pretreatment of ECFCs with the MEK-ERK pathway inhibitor U0126 or the PI3K-AKT pathway inhibitors, LY294002 or Wortmannin, blocked the periostin peptide-stimulated migration of ECFCs. These results suggest that the synthetic periostin peptide can be applied for stimulating angiogenic and therapeutic potentials of ECFCs.

Attack-Phase Bdellovibrio bacteriovorus Responses to Extracellular Nutrients Are Analogous to Those Seen During Late Intraperiplasmic Growth

Bdellovibrio bacteriovorus is a predatory bacterium which lives by invading the periplasm of gram-negative bacteria and consuming them from within. This predator was thought to be dependent upon prey for nutrients since it lacks genes encoding for critical enzymes involved in amino acid biosynthesis. This study, however, found that planktonic attack-phase predators are not just dependent upon prey for nutrients, but rather, they respond to nutrients in the surrounding medium and, subsequently, synthesize and secrete proteases in a nutrient-dependent manner. The major secreted proteases were identified through mass spectrometry analyses. Subsequent RT-qPCR analyses found that the nutrient-induced proteases are similar to those expressed within the prey periplasm during the late intraperiplasmic growth phase. Furthermore, RNA sequencing found that incubating the planktonic attack-phase cells in a nutritious environment for a short period of time (4 h) changes its gene expression pattern to a status that is akin to the late intraperiplasmic phase, with more than 94% of the genes previously identified as being late intraperiplasmic-specific also being induced by nutrient broth in this study. This strong correlation between the gene expression patterns hints that the availability of hydrolyzed prey cell components to the predator is likely the stimulus controlling the expression of late intraperiplasmic B. bacteriovorus genes during predation.

Structure-guided synthesis of a protein-based fluorescent sensor for alkyl halides

A new fluorescent hybrid sensor for alkyl halides was developed from the crystal structure of a holo-HaloTag protein complex.

Proximity-Directed Labeling Reveals a New Rapamycin-Induced Heterodimer of FKBP25 and FRB in Live Cells

Mammalian target of rapamycin (mTOR) signaling is a core pathway in cellular metabolism, and control of the mTOR pathway by rapamycin shows potential for the treatment of metabolic diseases. In this study, we employed a new proximity biotin-labeling method using promiscuous biotin ligase (pBirA) to identify unknown elements in the rapamycin-induced interactome on the FK506-rapamycin binding (FRB) domain in living cells. FKBP25 showed the strongest biotin labeling by FRB-pBirA in the presence of rapamycin. Immunoprecipitation and immunofluorescence experiments confirmed that endogenous FKBP25 has a rapamycin-induced physical interaction with the FRB domain. Furthermore, the crystal structure of the ternary complex of FRB-rapamycin-FKBP25 was determined at 1.67-Å resolution. In this crystal structure we found that the conformational changes of FRB generate a hole where there is a methionine-rich space, and covalent metalloid coordination was observed at C2085 of FRB located at the bottom of the hole. Our results imply that FKBP25 might have a unique physiological role related to metallomics in mTOR signaling.

Serum amyloid A inhibits RANKL-induced osteoclast formation

When mouse bone marrow-derived macrophages were stimulated with serum amyloid A (SAA), which is a major acute-phase protein, there was strong inhibition of osteoclast formation induced by the receptor activator of nuclear factor kappaB ligand. SAA not only markedly blocked the expression of several osteoclast-associated genes (TNF receptor-associated factor 6 and osteoclast-associated receptor) but also strongly induced the expression of negative regulators (MafB and interferon regulatory factor 8). Moreover, SAA decreased c-fms expression on the cell surface via shedding of the c-fms extracellular domain. SAA also restrained the fusion of osteoclast precursors by blocking intracellular ATP release. This inhibitory response of SAA is not mediated by the well-known SAA receptors (formyl peptide receptor 2, Toll-like receptor 2 (TLR2) or TLR4). These findings provide insight into a novel inhibitory role of SAA in osteoclastogenesis and suggest that SAA is an important endogenous modulator that regulates bone homeostasis.

Novel phosphorylation of PPARγ ameliorates obesity-induced adipose tissue inflammation and improves insulin sensitivity

Chronic inflammation in adipose tissue is highly associated with insulin resistance. Herein, we demonstrate that a novel modification of PPARγ is strongly associated with inflammatory responses in adipose tissue. c-Src kinase directly phosphorylated PPARγ at Tyr78, and this process was reversed by protein tyrosine phosphatase-1B (PTP-1B). In adipocytes, phosphorylation of PPARγ suppressed the expression of pro-inflammatory genes as well as the secretion of chemokines and cytokines, thus reducing macrophage migration. Importantly, pharmacological inhibition of c-Src kinase aggravated insulin resistance in obese mice with a concomitant increase in the expression of pro-inflammatory genes in adipose tissue. These data strongly suggest that PPARγ phosphorylation is the key regulatory mechanism of the inflammatory response in adipose tissue, which is highly associated with glucose tolerance and insulin sensitivity. Furthermore, these data increase our understanding of the mechanical aspects of developing novel anti-diabetic drugs targeting PPARγ phosphorylation.

A thioredoxin fold protein Sh3bgr regulates Enah and is necessary for proper sarcomere formation

The sh3bgr (SH3 domain binding glutamate-rich) gene encodes a small protein containing a thioredoxin-like fold, SH3 binding domain, and glutamate-rich domain. Originally, it was suggested that increased expression of Sh3bgr may cause the cardiac phenotypes in Down's syndrome. However, it was recently reported that the overexpression of Sh3bgr did not cause any disease phenotypes in mice. In this study, we have discovered that Sh3bgr is critical for sarcomere formation in striated muscle tissues and also for heart development. Sh3bgr is strongly expressed in the developing somites and heart in Xenopus. Morpholino mediated-knockdown of sh3bgr caused severe malformation of heart tissue and disrupted segmentation of the somites. Further analysis revealed that Sh3bgr specifically localized to the Z-line in mature sarcomeres and that knockdown of Sh3bgr completely disrupted sarcomere formation in the somites. Moreover, overexpression of Sh3bgr resulted in abnormally discontinues thick firmaments in the somitic sarcomeres. We suggest that Sh3bgr does its function at least partly by regulating localization of Enah for the sarcomere formation. In addition, we provide the data supporting Sh3bgr is also necessary for proper heart development in part by affecting the Enah protein level.

Detection of admittivity anomaly on high-contrast heterogeneous backgrounds using frequency difference EIT

This paper describes a multiple background subtraction method in frequency difference electrical impedance tomography (fdEIT) to detect an admittivity anomaly from a high-contrast background conductivity distribution. The proposed method expands the use of the conventional weighted frequency difference EIT method, which has been used limitedly to detect admittivity anomalies in a roughly homogeneous background. The proposed method can be viewed as multiple weighted difference imaging in fdEIT. Although the spatial resolutions of the output images by fdEIT are very low due to the inherent ill-posedness, numerical simulations and phantom experiments of the proposed method demonstrate its feasibility to detect anomalies. It has potential application in stroke detection in a head model, which is highly heterogeneous due to the skull.

Spiraeoside inhibits mast cells activation and IgE-mediated allergic responses by suppressing phospholipase C-γ-mediated signaling

Mast cells are responsible for IgE-mediated allergic responses through the secretion of various inflammatory cytokines and mediators. Therefore, the pharmacological regulation of mast cell activation is an important goal in the development of novel anti-allergic drugs. In this study, we found that spiraeoside (SP) inhibits mast cell activation and allergic responses in vivo. SP dose-dependently inhibited the degranulation induced by IgE-antigen (Ag) stimulation in RBL-2H3 mast cells without cytotoxic effects. At the molecular level, SP reduced the Ag-induced phosphorylation and subsequent activation of phospholipase C-γ2 (PLC-γ2). Moreover, SP inhibited the phosphorylation of spleen tyrosine kinase (Syk), linker for activation of T cells (LAT), and downstream MAPKs, such as ERK1/2, p38, and JNK, eventually attenuating expression of TNF-α and IL-4. Finally, we found that SP significantly inhibited IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. Taken together, our results strongly suggest that SP suppresses IgE-mediated mast cell activation and allergic responses by inhibiting Lyn-induced PLC-γ2/MAPK signaling in mast cells.

Flightless-1, a novel transcriptional modulator of PPARγ through competing with RXRα

Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor family and plays key roles in glucose and lipid metabolism. Its transcriptional control of target genes is mediated by ligand-dependent recruitment of coactivators. In this study, we demonstrate that a novel transcriptional modulator of PPARγ, Flightless-I (FLII) binds directly to and suppresses the transcriptional activity of PPARγ. The LXXLL motif within the leucine-rich repeat (LRR) domain of FLII interacts directly with the DNA-binding domain of PPARγ. Interestingly, in the presence of PPARγ ligands, such as rosiglitazone and SR1664, this interaction was abolished in vitro. When FLII was overexpressed, both the transcriptional activity of PPARγ and adipogenesis were suppressed significantly, whereas specific knockdown of FLII reversed these effects. Furthermore, DNA occupancy of PPARγ on its target gene promoters was enhanced by FLII knockdown, and the interaction between PPARγ and retinoid X receptor α (RXRα) was blocked by FLII. Together, these findings strongly suggest that FLII functions in PPARγ activation as a molecular switch to repress transcriptional activity by interrupting formation of the PPARγ/RXRα complex, and FLII may serve as a novel therapeutic target in the treatment of adiposity-related metabolic syndromes.

Characterization of Cellulolytic and Xylanolytic Enzymes of Bacillus licheniformis JK7 Isolated from the Rumen of a Native Korean Goat

A facultative bacterium producing cellulolytic and hemicellulolytic enzymes was isolated from the rumen of a native Korean goat. The bacterium was identified as a Bacillus licheniformis on the basis of biochemical and morphological characteristics and 16S rDNA sequences, and has been designated Bacillus licheniformis JK7. Endoglucanase activities were higher than those of β-glucosidase and xylanase at all temperatures. Xylanase had the lowest activity among the three enzymes examined. The optimum temperature for the enzymes of Bacillus licheniformis JK7 was 70°C for endoglucanase (0.75 U/ml) and 50°C for β-glucosidase and xylanase (0.63 U/ml, 0.44 U/ml, respectively). All three enzymes were stable at a temperature range of 20 to 50°C. At 50°C, endoglucanse, β-glucosidase, and xylanase had 90.29, 94.80, and 88.69% residual activity, respectively. The optimal pH for the three enzymes was 5.0, at which their activity was 1.46, 1.10, and 1.08 U/ml, respectively. The activity of all three enzymes was stable in the pH range of 3.0 to 6.0. Endoglucanase activity was increased 113% by K⁺, while K⁺, Zn⁺, and tween 20 enhanced β-glucosidase activity. Xylanase showed considerable activity even in presence of selected chemical additives, with the exception of Mn²⁺ and Cu²⁺. The broad range of optimum temperatures (20 to 40°C) and the stability under acidic pH (4 to 6) suggest that the cellulolytic enzymes of Bacillus licheniformis JK7 may be good candidates for use in the biofuel industry.