Thiol-catalyzed formation of NO-ferroheme regulates intravascular NO signaling.

Nitric oxide (NO) is an endogenously produced signaling molecule that regulates blood flow and platelet activation. However, intracellular and intravascular diffusion of NO are limited by scavenging reactions with several hemoproteins, raising questions as to how free NO can signal in hemoprotein-rich environments. We explore the hypothesis that NO can be stabilized as a labile ferrous heme-nitrosyl complex (Fe2+-NO, NO-ferroheme). We observe a reaction between NO, labile ferric heme (Fe3+) and reduced thiols to yield NO-ferroheme and a thiyl radical. This thiol-catalyzed reductive nitrosylation occurs when heme is solubilized in lipophilic environments such as red blood cell membranes or bound to serum albumin. The resulting NO-ferroheme resists oxidative inactivation, is soluble in cell membranes and is transported intravascularly by albumin to promote potent vasodilation. We therefore provide an alternative route for NO delivery from erythrocytes and blood via transfer of NO-ferroheme and activation of apo-soluble guanylyl cyclase.

The bidirectional effect of neutrophils on periodontitis model in mice: A systematic review.

OBJECTIVE: To evaluate the regulatory role of neutrophils as the first line of host immune defense in the periodontal microenvironment of mice. METHODS: A systematic search was performed using PubMed, Web of Science, and ScienceDirect databases for articles published between 2012 and 2023. In this review, articles investigating the effect of neutrophils on alveolar bone resorption in a mouse model of periodontitis were selected and evaluated according to eligibility criteria. Important variables that may influence outcomes were analyzed. RESULTS: Eleven articles were included in this systematic review. The results showed that because of their immune defense functions, the functional homeostasis of local neutrophils is critical for periodontal health. Neutrophil deficiency aggravates alveolar bone loss. However, several studies have shown that excessive neutrophil infiltration is positively correlated with alveolar bone resorption caused by periodontitis in mice. Therefore, the homeostasis of neutrophil function needs to be considered in the treatment of periodontitis. CONCLUSIONS: Pooled analysis suggests that neutrophils play a bidirectional role in periodontal tissue remodeling in mouse periodontitis models. Therefore, targeted regulation of local neutrophil function provides a novel strategy for the treatment of periodontitis.

Lactobacillus rhamnosus inhibits osteoclast differentiation by suppressing the TLR2/NF-κB pathway.

OBJECTIVE: This study aimed to investigate the role of ultrasonicated Lactobacillus rhamnosus extract in osteoclast differentiation and its underlying mechanism, providing new strategies for the treatment of periodontitis. MATERIALS AND METHODS: Osteoclasts were induced using macrophage colony-stimulating factor and receptor activator for nuclear factor-κB ligand. Lactobacillus rhamnosus extracts were obtained via ultrasonic crushing and ultracentrifugation. The effects of the LGG extract on osteoclast differentiation were evaluated, and the related signaling pathways were examined using western blotting. A mouse periodontitis model was established, and Lactobacillus rhamnosus extract was injected into the gingival sulcus to evaluate the inhibitory effect of Lactobacillus rhamnosus extract on alveolar bone resorption. RESULTS: At 50 µg/mL, Lactobacillus rhamnosus extract inhibited osteoclast differentiation with no effect on apoptosis and proliferation. This phenomenon was achieved by deactivating the NF-κB/c-Fos/NFATc1 signaling pathway through toll-like receptor 2. The in vivo results showed that the local injection of Lactobacillus rhamnosus extract suppressed osteoclast differentiation and alveolar bone resorption. CONCLUSION: The ultrasonicated extract of Lactobacillus rhamnosus inhibited osteoclast differentiation by suppressing the activation of the NF-κB/c-Fos/NFATc1 pathway. Furthermore, it inhibited the destruction of the alveolar bone, providing a new strategy for the use of probiotics in the treatment of periodontitis.

DNA methylation alterations and their potential influence on macrophage in periodontitis.

OBJECTIVES: To explore how various methylation mechanisms function and affect macrophages in periodontitis, with an aim of getting a comprehensive understanding of pathogenesis of the disease. SUBJECT: Alterations in DNA methylation are associated with different periodontitis susceptible factors and disrupt immunity homeostasis. The host's immune response to stimulus plays a vital role in the progression of periodontitis. Macrophages are key immune cells of immune system. They act as critical regulators in maintaining issue homeostasis with their nature of high plasticity. The altered methylation status of genes may cause abnormal expression of proteins in the progress of periodontitis, thus, exert potential influence on macrophages. RESULTS: Certain genes are selectively activated or silenced due to the changes in the methylation status, which causes the alteration of the expression level of cytokines/chemokines, signal molecules, extracellular matrix molecules, leads to the change in local microenvironment, affects activation states of immune cells including macrophages, thus influences the host immune response during periodontitis.. This results in differential susceptibility and therapeutic outcome. CONCLUSION: DNA methylation alteration may cause aberrant expression level of genes associated with periodontal diseases, thus results in deregulation of macrophages, which supports the prospect of using DNA methylation-related parameter as a new biomarker for the diagnosis and treatment of periodontitis.

Clinical and biochemical effect of laser as an adjunct to non-surgical treatment of chronic periodontitis.

OBJECTIVES: To evaluate the clinical and biochemical efficacy of laser therapy as an adjunct to non-surgical treatment in chronic periodontitis. METHODS: A systematic search was performed through the PubMed, EMBASE, and Cochrane Library for eligible articles published as of May 2, 2020, supplemented by information search in the System for Information on Programme Literature in Europe and a manual literature search. Only randomized controlled trials (RCTs) used to compare the adjunctive use of laser and non-surgical treatment alone with an observation period of at least 6 months were included. RESULTS: Sixteen RCTs with a total of 525 subjects were included. Meta-analysis suggested that the additional use of laser to scaling and root planing (SRP) showed significant superiority over SRP alone among most of clinical parameters involved. Regarding the GCF, although volume in the laser group was lower at week 4 and 12, no significant difference was found regarding the cytokines level. Subgroup analysis revealed that the combined therapy produced no significant difference in PD, CAL and PI at most time points for studies in respect to smokers. No treatment-related adverse events had been reported in the included studies. CONCLUSIONS: Pooled analysis suggested that laser-assisted non-surgical treatment improved clinical outcome to SRP alone in the management of non-smoking chronic periodontitis patients.

Effect of archwire plane and archwire size on anterior teeth movement in sliding mechanics in customized labial orthodontics: a 3D finite element study.

BACKGROUND: The aim of this study was to evaluate anterior teeth movement with different archwire planes and archwire sizes during space closure with and without miniscrew in sliding mechanics. METHODS: A 3D finite element method was applied to simulate anterior teeth retraction with and without miniscrew and power arm. Initial displacements and pressure stresses of periodontal tissue in anterior teeth were calculated after the teeth were applied with retraction forces with different archwire planes and archwire sizes. RESULTS: High archwire plane showed better torque control of anterior teeth in both sliding mechanics. With intramaxillary retraction, anterior teeth showed lingual tipping and extrusion movement, whereas larger-size archwires did not reduce it. In miniscrew sliding mechanics, anterior teeth showed labial tipping and intrusion movement. Compared with intramaxillary retraction, the retraction force produced less pressure stress on periodontal tissue in miniscrew sliding mechanics with long power arm. CONCLUSIONS: Higher archwire plane is conducive to anterior teeth torque control. In order to achieve the bodily movement of the anterior teeth during space closure, it is more important to choose the appropriate method (miniscrew sliding mechanics with long power arm), instead of increasing the size of the archwire.

Structural insights into a unique preference for 3' terminal guanine of mirtron in Drosophila TUTase tailor.

Terminal uridylyl transferase (TUTase) is one type of enzyme that modifies RNA molecules by facilitating the post-transcriptional addition of uridyl ribonucleotides to their 3' ends. Recent researches have reported that Drosophila TUTase, Tailor, exhibits an intrinsic preference for RNA substrates ending in 3'G, distinguishing it from any other known TUTases. Through this unique feature, Tailor plays a crucial role as the repressor in the biogenesis pathway of splicing-derived mirtron pre-miRNAs. Here we describe crystal structures of core catalytic domain of Tailor and its complexes with RNA stretches 5'-AGU-3' and 5'-AGUU-3'. We demonstrate that R327 and N347 are two key residues contributing cooperatively to Tailor's preference for 3'G, and R327 may play an extra role in facilitating the extension of polyuridylation chain. We also demonstrate that conformational stability of the exit of RNA-binding groove also contributes significantly to Tailor's activity. Overall, our work reveals useful insights to explain why Drosophila Tailor can preferentially select RNA substrates ending in 3'G and provides important values for further understanding the biological significances of biogenesis pathway of mirtron in flies.

Crystal structure of Arabidopsis terminal uridylyl transferase URT1.

3' uridylation is an essential modification associated with coding and noncoding RNA degradation in eukaryotes. In Arabidopsis, HESO1 was first identified as the major nucleotidyl transferase that uridylates most unmethylated miRNAs, and URT1 was later reported to play a redundant but important role in miRNA uridylation when HESO1 is absent. Two enzymes work sequentially and collaboratively to tail different forms of the same miRNAs in vivo. For mRNA, however, URT1 becomes the main enzyme to uridylate the majority of mRNA and repairs their deadenylated ends to restore the binding site for Poly(A) Binding Protein (PABP). HESO1, on the other hand, targets mostly the mRNAs with very short oligo(A) tails and fails in fulfilling the same task. To understand the structural basis these two functional homologues possess for their different substrate preferences and catalytic behaviors, we first determined the crystal structures of URT1 in the absence and presence of UTP. Our structures, together with functional assay and sequence analysis, indicated that URT1 has a conserved UTP-recognition mechanism analogue to the terminal uridylyl transferases from other species whereas HESO1 may evolve separately to recognize UTP in a different way. Moreover, URT1 N552 may be an important residue in interacting with 3' nucleotide of RNA substrate. The URT1 structure we determined represents the first structure of uridylyl transferase from plants, shedding light on the mechanisms of URT1/HESO1-dependent RNA metabolism.

Unveiling the structural features that determine the dual methyltransferase activities of Streptococcus pneumoniae RlmCD.

Methyltransferase RlmCD was previously shown to be responsible for the introduction of C5 methylation at both U747 and U1939 of the 23S ribosomal RNA in Streptococcus pneumoniae. Intriguingly, its structural homologue, RumA, can only catalyze the methylation of U1939, while RlmC is the dedicated enzyme for m5U747 in Escherichia coli. In this study, we describe the structure of RlmCD in complex with its cofactor and the RNA substrate containing U747 at 2.00 Å or U1939 at 3.10 Å. We demonstrate that multiple structural features collaborate to establish the dual enzymatic activities of RlmCD. Of them, the side-chain rearrangement of F145 was observed to be an unusual mechanism through which RlmCD can discriminate between U747- and U1939-containing RNA substrate by switching the intermolecular aromatic stacking between protein and RNA on/off. An in-vitro methyltransferase assay and electrophoretic mobility shift assay were performed to validate these findings. Overall, our complex structures allow for a better understanding of the dual-functional mechanism of RlmCD, suggesting useful implications for the evolution of the RumA-type enzyme and the potential development of antibiotic drugs against S. pneumoniae.

Dual-utility NLS drives RNF169-dependent DNA damage responses.

Loading of p53-binding protein 1 (53BP1) and receptor-associated protein 80 (RAP80) at DNA double-strand breaks (DSBs) drives cell cycle checkpoint activation but is counterproductive to high-fidelity DNA repair. ring finger protein 169 (RNF169) maintains the balance by limiting the deposition of DNA damage mediator proteins at the damaged chromatin. We report here that this attribute is accomplished, in part, by a predicted nuclear localization signal (NLS) that not only shuttles RNF169 into the nucleus but also promotes its stability by mediating a direct interaction with the ubiquitin-specific protease USP7. Guided by the crystal structure of USP7 in complex with the RNF169 NLS, we uncoupled USP7 binding from its nuclear import function and showed that perturbing the USP7-RNF169 complex destabilized RNF169, compromised high-fidelity DSB repair, and hypersensitized cells to poly (ADP-ribose) polymerase inhibition. Finally, expression of USP7 and RNF169 positively correlated in breast cancer specimens. Collectively, our findings uncover an NLS-mediated bipartite mechanism that supports the nuclear function of a DSB response protein.

Structural basis for the specific recognition of 18S rRNA by APUM23.

PUF (Pumilio/fem-3 mRNA binding factor) proteins, a conserved family of RNA-binding proteins, recognize specific single-strand RNA targets in a specific modular way. Although plants have a greater number of PUF protein members than do animal and fungal systems, they have been the subject of fewer structural and functional investigations. The aim of this study was to elucidate the involvement of APUM23, a nucleolar PUF protein in the plant Arabidopsis, in pre-rRNA processing. APUM23 is distinct from classical PUF family proteins, which are located in the cytoplasm and bind to 3'UTRs of mRNA to modulate mRNA expression and localization. We found that the complete RNA target sequence of APUM23 comprises 11 nt in 18S rRNA at positions 1141-1151. The complex structure shows that APUM23 has 10 PUF repeats; it assembles into a C-shape, with an insertion located within the inner concave surface. We found several different RNA recognition features. A notable structural feature of APUM23 is an insertion in the third PUF repeat that participates in nucleotide recognition and maintains the correct conformation of the target RNA. Our findings elucidate the mechanism for APUM23's-specific recognition of 18S rRNA.

A novel RNA-binding mode of the YTH domain reveals the mechanism for recognition of determinant of selective removal by Mmi1.

The YTH domain-containing protein Mmi1, together with other factors, constitutes the machinery used to selectively remove meiosis-specific mRNA during the vegetative growth of fission yeast. Mmi1 directs meiotic mRNAs to the nuclear exosome for degradation by recognizing their DSR (determinant of selective removal) motif. Here, we present the crystal structure of the Mmi1 YTH domain in the apo state and in complex with a DSR motif, demonstrating that the Mmi1 YTH domain selectively recognizes the DSR motif. Intriguingly, Mmi1 also contains a potential m(6)A (N(6)-methyladenine)-binding pocket, but its binding of the DSR motif is dependent on a long groove opposite the m(6)A pocket. The DSR-binding mode is distinct from the m(6)A RNA-binding mode utilized by other YTH domains. Furthermore, the m(6)A pocket cannot bind m(6)A RNA. Our structural and biochemical experiments uncover the mechanism of the YTH domain in binding the DSR motif and help to elucidate the function of Mmi1.

Structural Basis for the Specific Recognition of RhoA by the Dual GTPase-activating Protein ARAP3.

ARAP3 (Arf-GAP with Rho-GAP domain, ANK repeat, and PH domain-containing protein 3) is unique for its dual specificity GAPs (GTPase-activating protein) activity for Arf6 (ADP-ribosylation factor 6) and RhoA (Ras homolog gene family member A) regulated by phosphatidylinositol 3,4,5-trisphosphate and a small GTPase Rap1-GTP and is involved in regulation of cell shape and adhesion. However, the molecular interface between the ARAP3-RhoGAP domain and RhoA is unknown, as is the substrates specificity of the RhoGAP domain. In this study, we solved the crystal structure of RhoA in complex with the RhoGAP domain of ARAP3. The structure of the complex presented a clear interface between the RhoGAP domain and RhoA. By analyzing the crystal structure and in combination with in vitro GTPase activity assays and isothermal titration calorimetry experiments, we identified the crucial residues affecting RhoGAP activity and substrates specificity among RhoA, Rac1 (Ras-related C3 botulinum toxin substrate 1), and Cdc42 (cell division control protein 42 homolog).

Ginsenoside Rg1 Ameliorates Motor Function in an Animal Model of Parkinson's Disease.

AIMS: Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons in the substantia nigra (SN) and diminished dopamine levels in the striatum. Accumulating evidence supported that ginsenoside Rg1, the major pharmacologically active compound of ginseng, has a wide range of neurotrophic and neuroprotective effects under physiological and pathological conditions. Although Rg1 administration protects dopaminergic neurons in a rat model of PD, it is unclear if Rg1 treatment ameliorates motor function in PD. METHODS: Using the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that causes dopaminergic neurodegeneration, we investigated the effect of Rg1 on 3 tests of motor behaviors in mice: the accelerating rotarod, wire suspension and pole tests. RESULTS: The results showed that Rg1 treatment (10 mg/kg, i.p.) succeeded in restoring motor functions to physiological level in MPTP-treated mice. Importantly, these behavioral ameliorations were accompanied by an attenuation of the MPTP-induced loss of dopaminergic neurons in the SN and striatum. CONCLUSIONS: These findings indicate that Rg1 can significantly rescue the deficit of motor function in mice model of PD, and suggest that Rg1 may be a potential therapeutic agent against PD and related disorders.

Overexpression of SPP1 is a prognostic indicator of immune infiltration in lung adenocarcinoma.

OBJECTIVE: The extracellular phosphoprotein, secreted phosphoprotein 1 (SPP1), plays a crucial role in various tumors and regulating the immune system. This study aimed to evaluate its prognostic value and relationship to immune infiltration in lung adenocarcinoma (LUAD). METHODS: In the TCGA and GEO datasets, the information on clinic and transcriptome analysis of SPP1 in non-small-cell lung cancer (NSCLC) was examined accordingly. The association of SPP1 expression with overall survival and clinicopathologic characteristics was investigated by univariate and multivariate analysis. CancerSEA database was utilized to investigate the role of SPP1 at the cellular level by single-cell analysis. Additionally, the CIBERSORT algorithm was utilized to assess the correlation among the immune cells that infiltrated. RESULTS: NSCLC tissues exhibited a notable rise in SPP1 expression compared with that of normal tissues. Furthermore, the overexpression of SPP1 was substantially associated with clinicopathological features and unfavorable survival outcomes in individuals with LUAD, whereas no such correlation was observed in lung squamous cell carcinoma. Immune cells that infiltrate tumors and their corresponding genes were associated with SPP1 expression levels in LUAD. CONCLUSIONS: SPP1 is a reliable indicator for assessing LUAD immune infiltration status and prognosis. With this approach, SPP1 can help earlier LUAD diagnosis and act as a possible immunotherapy target.

Porphyromonas gingivalis aggravates colitis via a gut microbiota-linoleic acid metabolism-Th17/Treg cell balance axis.

Periodontitis is closely related to inflammatory bowel disease (IBD). An excessive and non-self-limiting immune response to the dysbiotic microbiome characterizes the two. However, the underlying mechanisms that overlap still need to be clarified. We demonstrate that the critical periodontal pathogen Porphyromonas gingivalis (Pg) aggravates intestinal inflammation and Th17/Treg cell imbalance in a gut microbiota-dependent manner. Specifically, metagenomic and metabolomic analyses shows that oral administration of Pg increases levels of the Bacteroides phylum but decreases levels of the Firmicutes, Verrucomicrobia, and Actinobacteria phyla. Nevertheless, it suppresses the linoleic acid (LA) pathway in the gut microbiota, which was the target metabolite that determines the degree of inflammation and functions as an aryl hydrocarbon receptor (AHR) ligand to suppress Th17 differentiation while promoting Treg cell differentiation via the phosphorylation of Stat1 at Ser727. Therapeutically restoring LA levels in colitis mice challenged with Pg exerts anti-colitis effects by decreasing the Th17/Treg cell ratio in an AHR-dependent manner. Our study suggests that Pg aggravates colitis via a gut microbiota-LA metabolism-Th17/Treg cell balance axis, providing a potential therapeutically modifiable target for IBD patients with periodontitis.

Chirality-induced Magnet-free Spin Generation in a Semiconductor.

Electrical generation and transduction of polarized electron spins in semiconductors are of central interest in spintronics and quantum information science. While spin generation in semiconductors has been frequently realized via electrical injection from a ferromagnet, there are significant advantages in nonmagnetic pathways of creating spin polarization. One such pathway exploits the interplay of electron spin with chirality in electronic structures or real space. Here, utilizing chirality-induced spin selectivity (CISS), we demonstrate efficient creation of spin accumulation in n-doped GaAs via electric current injection from a normal metal (Au) electrode through a self-assembled monolayer of chiral molecules (α-helix L-polyalanine, AHPA-L). The resulting spin polarization is detected as a Hanle effect in the n-GaAs, which is found to obey a distinct universal scaling with temperature and bias current consistent with chirality-induced spin accumulation. The experiment constitutes a definitive observation of CISS in a fully nonmagnetic device structure and demonstration of its ability to generate spin accumulation in a conventional semiconductor. The results thus place key constraints on the physical mechanism of CISS and present a new scheme for magnet-free semiconductor spintronics. This article is protected by copyright. All rights reserved.

Green location-oriented policies and carbon efficiency: a quasi-natural experiment from National Eco-industrial Demonstration Parks in China.

This paper investigates how National Eco-industrial Demonstration Parks (NEDP) in China affects carbon emission efficiency. The difference-in-differences (DID) strategy is used for analysis. This paper finds that the construction of NEDP is conducive to the improvement of carbon emission efficiency, and the findings remain robust through placebo tests and propensity score matching. Heterogeneity analysis shows NEDP construction has greater utility on carbon efficiency in non-resource-based cities as well as in environmentally friendly cities. The mechanism analysis found that green technology innovation, industrial restructuring, and the relocation of industrial enterprises are effective ways to improve carbon efficiency in NEDP. Finally, this paper finds that the construction of NEDP has obvious spatial spillover effects on carbon efficiency, which can effectively heighten the carbon efficiency level of this locality and nearby areas.

Metabolic regulation of dendritic cell activation and immune function during inflammation.

Dendritic cells (DCs) are antigen-presenting cells that bridge innate and adaptive immune responses. Multiple cell types, including DCs, rely on cellular metabolism to determine their fate. DCs substantially alter cellular metabolic pathways during activation, such as oxidative phosphorylation, glycolysis, fatty acid and amino acid metabolism, which have crucial implications for their functionality. In this review, we summarize and discuss recent progress in DC metabolic studies, focusing on how metabolic reprogramming influences DC activation and functionality and the potential metabolic differences among DC subsets. Improving the understanding of the relationship between DC biology and metabolic regulation may provide promising therapeutic targets for immune-mediated inflammatory diseases.

Mesenchymal stem cell-derived apoptotic bodies alleviate alveolar bone destruction by regulating osteoclast differentiation and function.

Periodontitis is caused by overactive osteoclast activity that results in the loss of periodontal supporting tissue and mesenchymal stem cells (MSCs) are essential for periodontal regeneration. However, the hypoxic periodontal microenvironment during periodontitis induces the apoptosis of MSCs. Apoptotic bodies (ABs) are the major product of apoptotic cells and have been attracting increased attention as potential mediators for periodontitis treatment, thus we investigated the effects of ABs derived from MSCs on periodontitis. MSCs were derived from bone marrows of mice and were cultured under hypoxic conditions for 72 h, after which ABs were isolated from the culture supernatant using a multi-filtration system. The results demonstrate that ABs derived from MSCs inhibited osteoclast differentiation and alveolar bone resorption. miRNA array analysis showed that miR-223-3p is highly enriched in those ABs and is critical for their therapeutic effects. Targetscan and luciferase activity results confirmed that Itgb1 is targeted by miR-223-3p, which interferes with the function of osteoclasts. Additionally, DC-STAMP is a key regulator that mediates membrane infusion. ABs and pre-osteoclasts expressed high levels of DC-STAMP on their membranes, which mediates the engulfment of ABs by pre-osteoclasts. ABs with knock-down of DC-STAMP failed to be engulfed by pre-osteoclasts. Collectively, MSC-derived ABs are targeted to be engulfed by pre-osteoclasts via DC-STAMP, which rescued alveolar bone loss by transferring miR-223-3p to osteoclasts, which in turn led to the attenuation of their differentiation and bone resorption. These results suggest that MSC-derived ABs are promising therapeutic agents for the treatment of periodontitis.