Structural insights into caspase ADPR deacylization catalyzed by a bacterial effector and host calmodulin.

Programmed cell death and caspase proteins play a pivotal role in host innate immune response combating pathogen infections. Blocking cell death is employed by many bacterial pathogens as a universal virulence strategy. CopC family type III effectors, including CopC from an environmental pathogen Chromobacterium violaceum, utilize calmodulin (CaM) as a co-factor to inactivate caspases by arginine ADPR deacylization. However, the molecular basis of the catalytic and substrate/co-factor binding mechanism is unknown. Here, we determine successive cryo-EM structures of CaM-CopC-caspase-3 ternary complex in pre-reaction, transition, and post-reaction states, which elucidate a multistep enzymatic mechanism of CopC-catalyzed ADPR deacylization. Moreover, we capture a snapshot of the detachment of modified caspase-3 from CopC. These structural insights are validated by mutagenesis analyses of CopC-mediated ADPR deacylization in vitro and animal infection in vivo. Our study offers a structural framework for understanding the molecular basis of arginine ADPR deacylization catalyzed by the CopC family.

Heterostructures Assembled from Bi2O2CO3 and MXene for Boosted Potassium-Ion Storage by Arousing the Built-in Electric Field.

Bismuth-based materials have been recognized as the appealing anodes for potassium-ion batteries (PIBs) due to their high theoretical capacity. However, the kinetics sluggishness and capacity decline induced by the structure distortion predominately retard their further development. Here, a heterostructure of polyaniline intercalated Bi2O2CO3/MXene (BOC-PA/MXene) hybrids is reported via simple self-assembly strategy. The ingenious design of heterointerface-rich architecture motivates significantly the interior self-built-in electric field (IEF) and high-density electron flow, thus accelerating the charge transfer and boosting ion diffusion. As a result, the hybrids realize a high reversible specific capacity, satisfying rate capability as well as long-term cycling stability. The in/ex situ characterizations further elucidate the stepwise intercalation-conversion-alloying reaction mechanism of BOC-PA/MXene. More encouragingly, the full cell investigation further highlights its competitive merits for practical application in further PIBs. The present work not only opens the way to the design of other electrodes with an appropriate working mechanism but also offers inspiration for built-in electric-field engineering toward high-performance energy storage devices.

Engineering High-Tortuosity 3D Gradient Structure and CFD-Assisted Multifield Analysis for Solar Interfacial Evaporation.

Solar interfacial evaporation is a promising method for solving the global shortage of fresh water. While 2D evaporators can efficiently localize solar-converted heat at the thin layer of the water-air interface, 3D solar evaporators can maximize energy reutilization while maintaining effective mass transport ability, few studies are conducted to explore the effect of gradient porosity on evaporation performance. In this study, a multifield assisted strategy based on a gradient 3D structure with high tortuosity is proposed, which creates a thermal field environment for efficient evaporation through high absorption of sunlight and excellent photothermal conversion and uses the gradient structure to optimize the internal pressure field to enhance water evaporation and transport. This hierarchically nanostructured solar absorber, with porosity inhomogeneity-induced pressure gradient and optimized temperature management, is a valuable design idea for manufacturing a more efficient 3D solar evaporator in the field of seawater desalination. Owing to the understanding of optimizing the dimension by various simulation parameters, the evaporation efficiencies of such structures are found to be 165.7%, suppressing the most evaporator. Moreover, it can provide new ideas and references for the fields of mass transfer and thermal management.

Cloning, heterologous expression, and molecular characterization of a highly active and stable non-specific endonuclease from Pseudomonas fluorescens.

Non-specific endonucleases can be used for the digestion of nucleic acids because they hydrolyze DNA/RNA into 3-5 base pairs (bp) length oligonucleotide fragments without strict selectivity. In this work, a novel non-specific endonuclease from Pseudomonas fluorescens (PfNuc) with high activities for both DNA and RNA was successfully cloned and expressed in Escherichia coli. The production of PfNuc in flask scale could be achieved to 1.73 × 106 U/L and 4.82 × 106 U/L for DNA and RNA by investigation of the culture and induction conditions. The characterization of PfNuc indicated that it was Mg2+-dependent and the catalytic activity was enhanced by 3.74 folds for DNA and 1.06 folds for RNA in the presence of 5 mM Mg2+. The specific activity of PfNuc for DNA was 1.44 × 105 U/mg at pH 8.0 and 40 °C, and 3.93 × 105 U/mg for RNA at pH 8.5 and 45 °C. The Km of the enzyme for both DNA and RNA was close to 43 µM. The Vmax was 6.40 × 105 U/mg and 1.11 × 106 U/mg for DNA and RNA, respectively. There was no observed activity loss when PfNuc was stored at 4 °C and - 20 °C after 28 days or 10 repeated freeze-thaw cycles at - 80 °C. Molecular docking revealed that PfNuc formed 17 and 19 hydrogen bonds with single-stranded RNA and double-stranded DNA, respectively. These results could explain the high activity and stability of PfNuc, suggesting its great potential applications in the industry and clinic.

Integrative metabolomics dictate distinctive signature profiles in patients with Tetralogy of Fallot.

BACKGROUND: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease (CCHD) with multifactorial etiology. We aimed to investigate the metabolic profiles of CCHD and their independent contributions to TOF. METHODS: A cohort comprising 42 individuals with TOF and atrial septal defect (ASD) was enrolled. Targeted ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) was employed to systematically analyze metabolite levels and identify TOF-associated metabolic profiles. RESULTS: Of 370 identified metabolites in tissue and 284 in plasma, over one-third of metabolites showed an association with microbiome. Differential metabolic pathways including amino acids biosynthesis, ABC (ATP-binding cassette) transporters, carbon metabolism, and fatty acid biosynthesis, shed light on TOF biological phenotypes. Additionally, ROC curves identified potential biomarkers, such as erythronic acid with an AUC of 0.868 in plasma, and 3-ß-hydroxy-bisnor-5-cholenic acid, isocitric acid, glutaric acid, ortho-Hydroxyphenylacetic acid, picolinic acid with AUC close to 1 in tissue, whereas the discriminative performance of those substances significantly improved when combined with clinical phenotypes. CONCLUSIONS: Distinct metabolic profiles exhibited robust discriminatory capabilities, effectively distinguishing TOF from ASD patients. These metabolites may serve as biomarkers or key molecular players in the intricate metabolic pathways involved in CCHD development. IMPACT: Distinct metabolic profiles exhibited robust discriminatory capabilities, effectively distinguishing Tetralogy of Fallot from atrial septal defect patients. Similar profiling but inconsistent differential pathways between plasma and tissue. More than one-third metabolites in plasma and tissue are associated with the microbiome. The discovery of biomarkers is instrumental in facilitating early detection and diagnosis of Tetralogy of Fallot. Disturbed metabolism offers insights into interpretation of pathogenesis of Tetralogy of Fallot.

LncRNA PSR Regulates Vascular Remodeling Through Encoding a Novel Protein Arteridin.

RATIONALE: Vascular smooth muscle cells (VSMCs) phenotype switch from contractile to proliferative phenotype is a pathological hallmark in various cardiovascular diseases. Recently, a subset of long noncoding RNAs was identified to produce functional polypeptides. However, the functional impact and regulatory mechanisms of long noncoding RNAs in VSMCs phenotype switching remain to be fully elucidated. OBJECTIVES: To illustrate the biological function and mechanism of a VSMC-enriched long noncoding RNA and its encoded peptide in VSMC phenotype switching and vascular remodeling. RESULTS: We identified a VSMC-enriched transcript encoded by a previously uncharacterized gene, which we called phenotype switching regulator (PSR), which was markedly upregulated during vascular remodeling. Although PSR was annotated as a long noncoding RNA, we demonstrated that the lncPSR (PSR transcript) also encoded a protein, which we named arteridin. In VSMCs, both arteridin and lncPSR were necessary and sufficient to induce phenotype switching. Mechanistically, arteridin and lncPSR regulate downstream genes by directly interacting with a transcription factor YBX1 (Y-box binding protein 1) and modulating its nuclear translocation and chromatin targeting. Intriguingly, the PSR transcription was also robustly induced by arteridin. More importantly, the loss of PSR gene or arteridin protein significantly attenuated the vascular remodeling induced by carotid arterial injury. In addition, VSMC-specific inhibition of lncPSR using adeno-associated virus attenuated Ang II (angiotensin II)-induced hypertensive vascular remodeling. CONCLUSIONS: PSR is a VSMC-enriched gene, and its transcript IncPSR and encoded protein (arteridin) coordinately regulate transcriptional reprogramming through a shared interacting partner, YBX1. This is a previously uncharacterized regulatory circuit in VSMC phenotype switching during vascular remodeling, with lncPSR/arteridin as potential therapeutic targets for the treatment of VSMC phenotype switching-related vascular remodeling.

Light-Driven Photocatalyst-Free Synthesis of ß, δ-Functionalized Ketones from Aldehydes.

The synthesis of ketones has been a long focus of chemistry research, on account of its unique reactivity. Herein, we report a simple light-driven photocatalyst-free synthesis of ß, δ-functionalized ketones from aldehydes, using inexpensive and commercially abundant feedstock chemicals. This reaction is enabled by the direct acyl radical generation via hydrogen atom transfer and the subsequent radical addition process, avoiding the need for prefunctionalized substrates and organometallic reagent.

Effective degradation of phenol by activating PMS with bimetallic Mo and Ni Co-doped g C3N4 composite catalyst: A Fenton-like degradation process promoted by non-free radical 1O2.

The application of bimetal supported graphite phase carbon nitride in activated peroxymonosulfate (PMS) process has become a research hotspot in recent years. In this study, 8-g C3N4/Mo/Ni composite catalyst material was successfully prepared by doping Mo and Ni in graphite phase carbon nitride. The bimetallic active sites were formed in the catalyst, and PMS was activated by the metal valence Mo6+/Mo4+ and Ni2+/Ni(0) through redox double cycle to effectively degrade phenol. When pH was neutral, the degradation rate of 20 mg/L phenol solution with 8-g C3N4/Mo/Ni (0.35 g/L) and PMS (0.6 mM) could reach 95% within 20 min. The degradation rate of 8-g C3N4/Mo/Ni/PMS catalytic system could reach more than 90% within 20min under the condition of pH range of 3-11 and different anions. Meanwhile, the degradation effects of RhB, MB and OFX on different pollutants within 30min were 99%, 100% and 82%, respectively. Electron spin resonance and quenching experiments showed that in 8-g C3N4/Mo/Ni/PMS system, the degradation mechanism was mainly non-free radicals, and the main active species in the degradation process was 1O2. This study provides a new idea for the study of bimetal supported graphite phase carbon nitride activation of PMS and the theoretical study of degradation mechanism.

Relationship between ischemic index, leakage index, and macular edema in branch retinal vein occlusion.

PURPOSE: To investigate the combined association of the ischemic index and leakage index with macular edema on ultra-widefield fluorescein angiography (UWFFA) in patients with branch retinal vein occlusion (BRVO). METHODS: Retrospective image analysis study. The leakage index and ischemic index were calculated using Fiji after aligning early and late UWFFA images. Differences in the ischemic index, leakage index, and central macular thickness (CMT) between ischemic and non-ischemic BRVO were compared. Moreover, the association between the ischemic index, leakage index, and macular edema was analyzed. RESULTS: Eighty-three patients with BRVO were enrolled, including 53 non-ischemic BRVO and 30 ischemic BRVO patients. No significant differences were observed in leakage index and CMT between ischemic BRVO and non-ischemic BRVO (all P > 0.05). In all included patients, CMT correlated with the panretina and all subregion leakage indexes (all P < 0.01), but not with the ischemic index (all P > 0.05). In the ischemic BRVO group, CMT showed a correlation with the leakage index in several regions, but not with the ischemic index. After adjusting for the ischemic index and other clinical features, CMT remained significantly correlated with the leakage index in all regions. CONCLUSION: The leakage index may be a more effective biomarker for monitoring BRVO-associated macular edema compared to the ischemic index. Further follow-up studies are warranted to validate these findings.

Rational design of small-molecules to recognize G-quadruplexes of c-MYC promoter and telomere and the evaluation of their in vivo antitumor activity against breast cancer.

DNA G4-structures from human c-MYC promoter and telomere are considered as important drug targets; however, the developing of small-molecule-based fluorescent binding ligands that are highly selective in targeting these G4-structures over other types of nucleic acids is challenging. We herein report a new approach of designing small molecules based on a non-selective thiazole orange scaffold to provide two-directional and multi-site interactions with flanking residues and loops of the G4-motif for better selectivity. The ligands are designed to establish multi-site interactions in the G4-binding pocket. This structural feature may render the molecules higher selectivity toward c-MYC G4s than other structures. The ligand-G4 interaction studied with 1H NMR may suggest a stacking interaction with the terminal G-tetrad. Moreover, the intracellular co-localization study with BG4 and cellular competition experiments with BRACO-19 may suggest that the binding targets of the ligands in cells are most probably G4-structures. Furthermore, the ligands that either preferentially bind to c-MYC promoter or telomeric G4s are able to downregulate markedly the c-MYC and hTERT gene expression in MCF-7 cells, and induce senescence and DNA damage to cancer cells. The in vivo antitumor activity of the ligands in MCF-7 tumor-bearing mice is also demonstrated.

HDAC inhibitors as a potential therapy for chemotherapy-induced neuropathic pain.

Cancer, a chronic disease characterized by uncontrolled cell development, kills millions of people globally. The WHO reported over 10 million cancer deaths in 2020. Anticancer medications destroy healthy and malignant cells. Cancer treatment induces neuropathy. Anticancer drugs cause harm to spinal cord, brain, and peripheral nerve somatosensory neurons, causing chemotherapy-induced neuropathic pain. The chemotherapy-induced mechanisms underlying neuropathic pain are not fully understood. However, neuroinflammation has been identified as one of the various pathways associated with the onset of chemotherapy-induced neuropathic pain. The neuroinflammatory processes may exhibit varying characteristics based on the specific type of anticancer treatment delivered. Neuroinflammatory characteristics have been observed in the spinal cord, where microglia and astrocytes have a significant impact on the development of chemotherapy-induced peripheral neuropathy. The patient's quality of life might be affected by sensory deprivation, loss of consciousness, paralysis, and severe disability. High cancer rates and ineffective treatments are associated with this disease. Recently, histone deacetylases have become a novel treatment target for chemotherapy-induced neuropathic pain. Chemotherapy-induced neuropathic pain may be treated with histone deacetylase inhibitors. Histone deacetylase inhibitors may be a promising therapeutic treatment for chemotherapy-induced neuropathic pain. Common chemotherapeutic drugs, mechanisms, therapeutic treatments for neuropathic pain, and histone deacetylase and its inhibitors in chemotherapy-induced neuropathic pain are covered in this paper. We propose that histone deacetylase inhibitors may treat several aspects of chemotherapy-induced neuropathic pain, and identifying these inhibitors as potentially unique treatments is crucial to the development of various chemotherapeutic combination treatments.

NIR-II Conjugated Electrolytes as Biomimetics of Lipid Bilayers for In Vivo Liposome Tracking.

Liposomes serve as promising and versatile vehicles for drug delivery. Tracking these nanosized vesicles, particularly in vivo, is crucial for understanding their pharmacokinetics. This study introduces the design and synthesis of three new conjugated electrolyte (CE) molecules, which emit in the second near-infrared window (NIR-II), facilitating deeper tissue penetration. Additionally, these CEs, acting as biomimetics of lipid bilayers, demonstrate superior compatibility with lipid membranes compared to commonly used carbocyanine dyes like DiR. To counteract the aggregation-caused quenching effect, CEs employ a twisted backbone, as such their fluorescence intensities can effectively enhance after a fluorophore multimerization strategy. Notably, a "passive" method was employed to integrate CEs into liposomes during the liposome formation, and membrane incorporation efficiency was significantly promoted to nearly 100%. To validate the in vivo tracking capability, the CE-containing liposomes were functionalized with cyclic arginine-glycine-aspartic acid (cRGD) peptides, serving as tumor-targeting ligands. Clear fluorescent images visualizing tumor site in living mice were captured by collecting the NIR-II emission. Uniquely, these CEs exhibit additional emission peak in visible region, enabling in vitro subcellular analysis using routine confocal microscopy. These results underscore the potential of CEs as a new-generation of membrane-targeting probes to facilitate the liposome-based medicine research.

Cryo-EM structure of mouse TRPML2 in lipid nanodiscs.

In mammalians, transient receptor potential mucolipin ion channels (TRPMLs) exhibit variable permeability to cations such as Ca2+, Fe2+, Zn2+, and Na+ and can be activated by the phosphoinositide PI(3,5)P2 in the endolysosomal system. Loss or dysfunction of TRPMLs has been implicated in lysosomal storage disorders, infectious diseases, and metabolic diseases. TRPML2 has recently been identified as a mechanosensitive and hypotonicity-sensitive channel in endolysosomal organelles, which distinguishes it from TRPML1 and TRPML3. However, the molecular and gating mechanism of TRPML2 remains elusive. Here, we present the cryo-EM structure of the full-length mouse TRPML2 in lipid nanodiscs at 3.14 Å resolution. The TRPML2 homotetramer structure at pH 7.4 in the apo state reveals an inactive conformation and some unique features of the extracytosolic/luminal domain and voltage sensor-like domain that have implications for the ion-conducting pathway. This structure enables new comparisons between the different subgroups of TRPML channels with available structures and provides structural insights into the conservation and diversity of TRPML channels. These comparisons have broad implications for understanding a variety of molecular mechanisms of TRPMLs in different pH conditions, including with and without bound agonists and antagonists.

Regiospecificity C(sp2)-C(sp3) Bond Construction between Purines and Alkenes to Synthesize C6-Alkylpurines and Purine Nucleosides Using O2 as the Oxidant.

A highly site-selective and Markovnikov-type radical C6-H alkylation of purines with alkenes is achieved, allowing fast construction of the C(sp2)-C(sp3) bond at the C-6-position of purines and purine nucleosides using O2 as a green oxidant and alkenes as cheap alkylation reagents. The route was also a radical route to synthesize C6-alkyl-N7-substituted purines with potential steric hindrance between C6-alkyl groups and N7-substituted groups. This reaction is easily scaled up and has excellent functional group compatibility and broad substrate scopes. Moreover, the unstable intermediate was also separated, which was the key evidence for the reaction mechanism.

LncRNA SNHG14/miR-497a-5p/BACE1 axis modulates obesity-induced adipocyte inflammation and endoplasmic reticulum stress.

Obesity is a metabolic disease with excess weight. LncRNA SNHG14 is abnormally expressed in numerous diseases. This research aimed to enucleate the lncRNA SNHG14 role in obesity. Adipocytes were treated with free fatty acid (FFA) to establish an in vitro model for obesity. Mice were fed a high-fat diet to construct an in vivo model. Gene levels were determined using quantitative real-time PCR (RT-PCR). The protein level was checked by western blot. The lncRNA SNHG14 role in obesity was assessed using western blot and enzyme-linked immunosorbent assay. The mechanism was estimated by Starbase, dual-luciferase reporter gene assay, and RNA pull-down. LncRNA SNHG14 function in obesity was estimated using mouse xenograft models, RT-PCR, western blot, and enzyme-linked immunosorbent assay. LncRNA SNHG14 and BACE1 levels were increased, but the miR-497a-5p level was decreased in FFA-induced adipocytes. Interference with lncRNA SNHG14 reduced endoplasmic reticulum (ER) stress-related molecules GRP78 and CHOP expressions in FFA-induced adipocytes, and decreased IL-1ß, IL-6, and TNF-α expressions, indicating that lncRNA SNHG14 knockdown mitigated FFA-induced ER stress and inflammation in adipocytes. Mechanistically, lncRNA SNHG14 combined with miR-497a-5p, and miR-497a-5p targeted BACE1. Meanwhile, lncRNA SNHG14 knockdown reduced levels of GRP78, CHOP, IL-1ß, IL-6, and TNF-α, while cotransfection with anti-miR-497a-5p or pcDNA-BACE1 abolished these trends. Rescue assays illustrated that lncRNA SNHG14 knockdown relieved FFA-induced adipocyte ER stress and inflammation through miR-497a-5p/BACE1. Meanwhile, lncRNA SNHG14 knockdown restrained adipose inflammation and ER stress caused by obesity in vivo. LncRNA SNHG14 mediated obesity-induced adipose inflammation and ER stress through miR-497a-5p/BACE1.

Visible Light-Induced Cascade Sulfonylation/Cyclization to Produce Quinoline-2,4-Diones under Metal-Free Conditions.

A general visible light-induced sulfonylation/cyclization to produce quinoline-2,4-diones was achieved under photocatalyst-free conditions. The reactions were performed at room temperature, and various substituents (halogen, alkyl, aryl) and substituted products were obtained with 29 examples within 2 h. Large-scale synthesis and derivatization study via carbonyl reduction to produce easily modified hydroxyl groups and convenient N-Ts deprotection showed the potential utility of this strategy.

Exosomal Wnt7a from a low metastatic subclone promotes lung metastasis of a highly metastatic subclone in the murine 4t1 breast cancer.

BACKGROUND: Patients with triple-negative breast cancer (TNBC) often have poorer prognosis than those with other subtypes because of its aggressive behaviors. Cancer cells are heterogeneous, and only a few highly metastatic subclones metastasize. Although the majority of subclones may not metastasize, they could contribute by releasing factors that increase the capacity of highly metastatic cells and/or provide a favorable tumor microenvironment (TME). Here, we analyzed the interclonal communication in TNBC which leads to efficient cancer progression, particularly lung metastasis, using the polyclonal murine 4T1 BC model. METHODS: We isolated two 4T1 subclones, LM.4T1 and HM.4T1 cells with a low and a high metastatic potential, respectively, and examined the effects of LM.4T1 cells on the behaviors of HM.4T1 cells using the cell scratch assay, sphere-forming assay, sphere invasion assay, RT-qPCR, and western blotting in vitro. We also examined the contribution of LM.4T1 cells to the lung metastasis of HM.4T1 cells and TME in vivo. To identify a critical factor which may be responsible for the effects by LM.4T1 cells, we analyzed the data obtained from the GEO database. RESULTS: Co-injection of LM.4T1 cells significantly augmented lung metastases by HM.4T1 cells. LM.4T1-derived exosomes promoted the migration and invasion of HM.4T1 cells in vitro, and blocking the secretion of exosome abrogated their effects on HM.4T1 cells. Analyses of data obtained from the GEO database suggested that Wnt7a might be a critical factor responsible for the enhancing effects. In fact, a higher level of Wnt7a was detected in LM.4T1 cells, especially in exosomes, than in HM.4T1 cells, and deletion of Wnt7a in LM.4T1 cells significantly decreased the lung metastasis of HM.4T1 cells. Further, treatment with Wnt7a increased the spheroid formation by HM.4T1 cells via activation of the PI3K/Akt/mTOR signaling pathway. Finally, infiltration of αSMA-positive fibroblasts and angiogenesis was more prominent in tumors of LM.4T1 cells and deletion of Wnt7a in LM.4T1 cells markedly reduced angiogenesis. CONCLUSIONS: We demonstrated, for the first time, that a low metastatic subclone can enhance lung metastasis of highly metastatic subclone via exosomal Wnt7a and propose Wnt7a as a molecular target to treat TNBC patients.

Spatial constraints on chromosomes are instrumental to meiotic pairing.

In most eukaryotes, the meiotic chromosomal bouquet (comprising clustered chromosome ends) provides an ordered chromosome arrangement that facilitates pairing and recombination between homologous chromosomes. In the protist Tetrahymena thermophila, the meiotic prophase nucleus stretches enormously, and chromosomes assume a bouquet-like arrangement in which telomeres and centromeres are attached to opposite poles of the nucleus. We have identified and characterized three meiosis-specific genes [meiotic nuclear elongation 1-3 (MELG1-3)] that control nuclear elongation, and centromere and telomere clustering. The Melg proteins interact with cytoskeletal and telomere-associated proteins, and probably repurpose them for reorganizing the meiotic prophase nucleus. A lack of sequence similarity between the Tetrahymena proteins responsible for telomere clustering and bouquet proteins of other organisms suggests that the Tetrahymena bouquet is analogous, rather than homologous, to the conserved eukaryotic bouquet. We also report that centromere clustering is more important than telomere clustering for homologous pairing. Therefore, we speculate that centromere clustering may have been the primordial mechanism for chromosome pairing in early eukaryotes.

Dual roles of ANGPTL4 in multiple inflammatory responses in stomatitis mice.

BACKGROUND: Stomatitis is inflammation of the oral mucosa. Angiopoietin-like protein 4 (ANGPTL4) has pleiotropic functions both anti-inflammatory and pro-inflammatory properties. In the present study, we tested whether there is a correlation between increased ANGPTL4 expression and inflammation in stomatitis mice and the mechanisms involved. METHODS AND RESULTS: In this study, the oral mucosa of mice was burned with 90% phenol and intraperitoneal injection of 5-fluorouracil to establish the model of stomatitis mice. The pathological changes of stomatitis mice were observed by H&E staining of paraffin section. The expressions of cytokines and ANGPTL4 were detected by fluorescence quantitative PCR, and the protein levels of ANGPTL4 were detected by western blot. Compared with control group, the oral mucosal structure of model mice was damaged. The expression of ANGPTL4 were significantly increased concomitantly with elevated production of anti-inflammatory cytokine (peroxisome proliferator-activated receptor alpha) and pro-inflammatory cytokines [nuclear transcription factor-kappa B, interleukin-6 (IL-6), IL-1ß, and tumor necrosis factor-α] in mice with stomatitis. CONCLUSIONS: This study suggests that ANGPTL4 may be a double-edged sword in multiple inflammatory responses in stomatitis mice.

An MCM family protein promotes interhomolog recombination by preventing precocious intersister repair of meiotic DSBs.

Recombinational repair of meiotic DNA double-strand breaks (DSBs) uses the homologous chromosome as a template, although the sister chromatid offers itself as a spatially more convenient substrate. In many organisms, this choice is reinforced by the recombination protein Dmc1. In Tetrahymena, the repair of DSBs, which are formed early in prophase, is postponed to late prophase when homologous chromosomes and sister chromatids become juxtaposed owing to tight parallel packing in the thread-shaped nucleus, and thus become equally suitable for use as repair templates. The delay in DSB repair is achieved by rejection of the invading strand by the Sgs1 helicase in early meiotic prophase. In the absence of Mcmd1, a meiosis-specific minichromosome maintenance (MCM)-like protein (and its partner Pamd1), Dmc1 is prematurely lost from chromatin and DNA synthesis (as monitored by BrdU incorporation) takes place in early prophase. In mcmd1Δ and pamd1Δ mutants, only a few crossovers are formed. In a mcmd1Δ hop2Δ double mutant, normal timing of Dmc1 loss and DNA synthesis is restored. Because Tetrahymena Hop2 is believed to enable homologous strand invasion, we conclude that Dmc1 loss in the absence of Mcmd1 affects only post-invasion recombination intermediates. Therefore, we propose that the Dmc1 nucleofilament becomes dismantled immediately after forming a heteroduplex with a template strand. As a consequence, repair synthesis and D-loop extension starts in early prophase intermediates and prevents strand rejection before the completion of homologous pairing. In this case, DSB repair may primarily use the sister chromatid. We conclude that Mcmd1‒Pamd1 protects the Dmc1 nucleofilament from premature dismantling, thereby suppressing precocious repair synthesis and excessive intersister strand exchange at the cost of homologous recombination.