mmu-miR-185 regulates osteoclasts differentiation and migration by targeting Btk.

BACKGROUND: Bones undergo a constant remodeling, a process involving osteoclast-mediated bone resorption and osteoblast-mediated bone formation, crucial for maintaining healthy bone mass. We previously observed that miR-185 depletion may promote bone formation by regulating Bgn expression and the BMP/Smad signaling pathway. However, the effects of miR-185-5p on the osteoclasts and bone remodeling have not been elucidated, warranting further exploration. METHODS: Tartrate-resistant acid phosphatase staining was utilized to assess the differentiation ability of bone marrow mononuclear macrophages (BMMs) from mmu-miR-185 gene knockout (KO) mice and wild-type (WT) mice. A reverse transcriptase-quantitative PCR was conducted to compare differences in miR-185-5p and osteoclast marker molecules, including Trap, Dcstamp, Ctsk and Nfatc1, between the KO group and WT group BMMs. Western blot analysis was employed to observe the expression of osteoclast marker molecules. A cell-counting kit-8 was used to analyze cell proliferation ability. Transwell experiments were conducted to detect cell migration. Dual-luciferase reporter assays were employed to confirm whether Btk is a downstream target gene of miR-185-5p. RESULTS: miR-185 depletion promoted osteoclast differentiation in bone marrow-derived monocytes/macrophages. Overexpression of miR-185-5p in RAW264.7 cells inhibited differentiation and migration of osteoclasts. Furthermore, Btk was identified as a downstream target gene of miR-185-5p, suggesting that miR-185-5p may inhibit osteoclast differentiation and migration by targeting Btk. CONCLUSIONS: miR-185 regulates osteoclasts differentiation, with overexpression of miR-185-5p inhibiting osteoclast differentiation and migration in vitro. Additionally, miR-185-5p may modulate osteoclastic differentiation and migration by regulating Btk expression.

Toward nanotechnology-enabled application of bilirubin in the treatment and diagnosis of various civilization diseases.

Bilirubin, an open chain tetrapyrrole, has powerful antioxidant, anti-inflammatory, immuno-suppressive, metabolic-modulating and anti-proliferative activities. Bilirubin is a natural molecule that is produced and metabolized within the human body, making it highly biocompatible and well suited for clinical use. However, the use of bilirubin has been hampered by its poor water solubility and instability. With advanced construction strategies, bilirubin-derived nanoparticles (BRNPs) have not only overcome the disadvantages of bilirubin but also enhanced its therapeutic effects by targeting damaged tissues, passing through physiological barriers, and ensuring controlled sustained release. We review the mechanisms underlying the biological activities of bilirubin, BRNP preparation strategies and BRNP applications in various disease models. Based on their superior performance, BRNPs require further exploration of their efficacy, biodistribution and long-term biosafety in nonhuman primate models that recapitulate human disease to promote their clinical translation.

Effects of bilirubin on the development and electrical activity of neural circuits.

In the past several decades, bilirubin has attracted great attention for central nervous system (CNS) toxicity in some pathological conditions with severely elevated bilirubin levels. CNS function relies on the structural and functional integrity of neural circuits, which are large and complex electrochemical networks. Neural circuits develop from the proliferation and differentiation of neural stem cells, followed by dendritic and axonal arborization, myelination, and synapse formation. The circuits are immature, but robustly developing, during the neonatal period. It is at the same time that physiological or pathological jaundice occurs. The present review comprehensively discusses the effects of bilirubin on the development and electrical activity of neural circuits to provide a systematic understanding of the underlying mechanisms of bilirubin-induced acute neurotoxicity and chronic neurodevelopmental disorders.

Dense-Packed RuO2 Nanorods with In Situ Generated Metal Vacancies Loaded on SnO2 Nanocubes for Proton Exchange Membrane Water Electrolyzer with Ultra-Low Noble Metal Loading.

Proton exchange membrane water electrolyzer (PEMWE) is a green hydrogen production technology that can be coupled with intermittent power sources such as wind and photoelectric power. To achieve cost-effective operations, low noble metal loading on the anode catalyst layer is desired. In this study, a catalyst with RuO2 nanorods coated outside SnO2 nanocubes is designed, which forms continuous networks and provides high conductivity. This allows for the reduction of Ru contents in catalysts. Furthermore, the structure evolutions on the RuO2 surface are carefully investigated. The etched RuO2 surfaces are seen as the consequence of Co leaching, and theoretical calculations demonstrate that it is more effective in driving oxygen evolution. For electrochemical tests, the catalysts with 23 wt% Ru exhibit an overpotential of 178 mV at 10 mA cm-2 , which is much higher than most state-of-art oxygen evolution catalysts. In a practical PEMWE, the noble metal Ru loading on the anode side is only 0.3 mg cm-2 . The cell achieves 1.61 V at 1 A cm-2 and proper stability at 500 mA cm-2 , demonstrating the effectiveness of the designed catalyst.

Bead-like carbon fibers consisting of abundantly exposed active sites for the oxygen reduction reaction.

Rational design is essential in the synthesis of electrocatalysts for the oxygen reduction reaction (ORR). Herein, we introduced zeolitic imidazolate framework-8 (ZIF-8) and polyvinyl pyrrolidone (PVP) into the electrospinning process of the polyacrylonitrile (PAN) and hemin to increase the active site loading and exposed active area of the final product with empty bead-like structures. In this method, ZIF-8 acts as a carbon skeleton to provide a rich microporous structure that can support active sites, and as a nitrogen dopant to improve nitrogen contents. PVP changes the properties of the spinning solution, adjusts the fiber morphology, and to increase the exposed area of active sites as a pore former. The obtained Fe-N-C ORR catalyst delivered a half-wave potential (E1/2) of 0.924 V in a 0.1 M KOH solution and 0.77 V in a 0.1 M HClO4solution. A homemade zinc air battery with power density of 236 mW cm-2demonstrated the excellent performance of the catalyst under working conditions.

Transforming C60 Molecules into Polyhedral Carbon Micro-Nano Shells for Electrochemically Producing H2O2 in Neutral Electrolytes.

The electrochemical production of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (ORR) can realize the customer-oriented onsite synthesis of H2O2 in a green and sustainable method. The ongoing challenge that needs to be solved is the fabrication of robust electrocatalysts of excellent performance. In this work, C60 was selected as a precursor due to its uniform structure and abundant pentagon rings. Thanks to the strong interaction between C60 and thiophene, after heteromolecule assembly in the liquid reaction and subsequent reconstruction of the carbon topological structure in solid calcination, C60 was successfully transformed into polyhedral carbon micro-nano shells (PCMNS) with an effective pore structure for the first time, which exhibited excellent capacity for production of H2O2 via two-electron ORR, especially in neutral media. In addition to the high onset potential (0.49 V vs reversible hydrogen electrode (RHE)) and low Tafel slope (72 mV dec-1), its selectivity reached >90% within the potential range of 0.30-0.45 V and maintained >80% after constant potential electrolysis for 10 h. The yield rate of H2O2 was 1102.5 mmol gcat-1 h-1, determined by an H-type electrolytic cell, which was one of the highest values of metal-free carbon-based ORR electrocatalysts ever reported. Such excellent two-electron ORR performance of PCMNS was attributed to its abundant accessible active sites and hierarchical pore structures.

OGA is associated with deglycosylation of NONO and the KU complex during DNA damage repair.

Accumulated evidence shows that OGT-mediated O-GlcNAcylation plays an important role in response to DNA damage repair. However, it is unclear if the "eraser" O-GlcNAcase (OGA) participates in this cellular process. Here, we examined the molecular mechanisms and biological functions of OGA in DNA damage repair, and found that OGA was recruited to the sites of DNA damage and mediated deglycosylation following DNA damage. The recruitment of OGA to DNA lesions is mediated by O-GlcNAcylation events. Moreover, we have dissected OGA using deletion mutants and found that C-terminal truncated OGA including the pseudo HAT domain was required for the recruitment of OGA to DNA lesions. Using unbiased protein affinity purification, we found that the pseudo HAT domain was associated with DNA repair factors including NONO and the Ku70/80 complex. Following DNA damage, both NONO and the Ku70/80 complex were O-GlcNAcylated by OGT. The pseudo HAT domain was required to recognize NONO and the Ku70/80 complex for their deglycosylation. Suppression of the deglycosylation prolonged the retention of NONO at DNA lesions and delayed NONO degradation on the chromatin, which impaired non-homologus end joining (NHEJ). Collectively, our study reveals that OGA-mediated deglycosylation plays a key role in DNA damage repair.

A graphene oxide coated tapered microfiber acting as a super-sensor for rapid detection of SARS-CoV-2.

COVID-19 is a new strain of highly contagious coronavirus, and at present, more than 221.4 million people have been infected with this virus, and the death toll exceeds 2793398. Early and fast detection of COVID-19 from infected individuals is critical to limit its spreading. Here, we report an innovative approach to detect the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein by combining DNA/RNA oligomers as aptamers and a graphene oxide (GO) coated optical microfiber as a sensor system. The DNA/RNA aptamers can effectively capture the SARS-CoV-2 N protein in vitro, with the GO coated optical microfiber aptasensor for real-time monitoring of the SARS-CoV-2 N protein. Due to the extremely high surface-to-volume ratio and excellent optical and biochemical properties of the GO surface layer, the fixing effect of the microfiber surface is significantly improved and the lowest limit of detection (LOD) is 6.25 × 10-19 M. Furthermore, in order to prove the feasibility of this sensing method in clinical applications, we use this sensor to detect the N protein mixed in fetal bovine serum (FBS) samples. The experimental results show that the biosensor can quickly and effectively detect the N protein (1 × 10-9 M) in a complex sample matrix within 3 minutes. These findings suggest that this approach can be utilized for quantitative monitoring of coronavirus particles due to its high sensitivity, which can help to quickly exclude patients who do not have the infection. Collectively, the optical microfiber sensor system could be expected to become an important platform for the diagnosis of coronavirus due to its simple detection scheme and easy miniaturization.

Surface-confinement assisted synthesis of nitrogen-rich single atom Fe-N/C electrocatalyst with dual nitrogen sources for enhanced oxygen reduction reaction.

The utilization of earth abundant iron and nitrogen doped carbon as a precious-metal-free electrocatalyst for oxygen reduction reaction (ORR) significantly depends on the rational design and construction of desired Fe-Nxmoieties on carbon substrates, which however remains an enormous challenge. Herein a typical nanoporous nitrogen-rich single atom Fe-N/C electrocatalyst on carbon nanotube (NR-CNT@FeN-PC) was successfully prepared by using CNT as carbon substrate, polyaniline (PANI) and dicyandiamine (DCD) as binary nitrogen sources and silica-confinement-assisted pyrolysis, which not only facilitate rich N-doping for the inhibition of the Fe agglomeration and the formation of single atom Fe-Nxsites in carbon matrix, but also generate more micropores for enlarging BET specific surface area (up to 1500 m2·g-1). Benefiting from the advanced composition, nanoporous structure and surface hydrophilicity to guarantee the sufficient accessible active sites for ORR, the NR-CNT@FeN-PC catalyst under optimized conditions delivers prominent ORR performance with a half-wave potential (0.88 V versus RHE) surpass commercial Pt/C catalyst by 20 mV in alkaline electrolyte. When assembled in a home-made Zn-air battery device as cathodic catalyst, it achieved a maximum output power density of 246 mW·cm-2and a specific capacity of 719 mA·h·g-1Znoutperformed commercial Pt/C catalyst, holding encouraging promise for the application in metal-air batteries.

The RNF20/40 complex regulates p53-dependent gene transcription and mRNA splicing.

p53 is a key transcription factor to regulate gene transcription. However, the molecular mechanism of chromatin-associated p53 on gene transcription remains elusive. Here, using unbiased protein affinity purification, we found that the RNF20/40 complex associated with p53 on the chromatin. Further analyses indicated that p53 mediated the recruitment of the RNF20/40 complex to p53 target gene loci including p21 and PUMA loci and regulated the transcription of p21 and PUMA via the RNF20/40 complex-dependent histone H2B ubiquitination (ubH2B). Lacking the RNF20/40 complex suppressed not only ubH2B but also the generation of the mature mRNA of p21 and PUMA. Moreover, ubH2B was recognized by the ubiquitin-binding motif of pre-mRNA processing splicing factor 8 (PRPF8), a subunit in the spliceosome, and PRPF8 was required for the maturation of the mRNA of p21 and PUMA. Our study unveils a novel p53-dependent pathway that regulates mRNA splicing for tumor suppression.

Effect of Ti Addition on the Microstructure and Mechanical Properties of SiC Matrix Composites Infiltrated by Al⁻Si (10 wt.%)⁻xTi Alloy.

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al⁻Si (10 wt.%)⁻xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al⁻Si (10 wt.%)⁻Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti3Si(Al)C2 phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti⁻Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti3Si(Al)C2 and Ti⁻Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti3Si(Al)C2 phase and small amounts of Ti⁻Al intermetallic compounds.

Author Correction: Molecular basis for the inhibition of the methyl-lysine binding function of 53BP1 by TIRR.

The original version of this Article contained an error in the author affiliations. Xiaochun Yu was incorrectly associated with College of Life Sciences, Hebei University, Baoding 071000 Hebei, China.This has now been corrected in both the PDF and HTML versions of the Article.

Molecular basis for the inhibition of the methyl-lysine binding function of 53BP1 by TIRR.

53BP1 performs essential functions in DNA double-strand break (DSB) repair and it was recently reported that Tudor interacting repair regulator (TIRR) negatively regulates 53BP1 during DSB repair. Here, we present the crystal structure of the 53BP1 tandem Tudor domain (TTD) in complex with TIRR. Our results show that three loops from TIRR interact with 53BP1 TTD and mask the methylated lysine-binding pocket in TTD. Thus, TIRR competes with histone H4K20 methylation for 53BP1 binding. We map key interaction residues in 53BP1 TTD and TIRR, whose mutation abolishes complex formation. Moreover, TIRR suppresses the relocation of 53BP1 to DNA lesions and 53BP1-dependent DNA damage repair. Finally, despite the high-sequence homology between TIRR and NUDT16, NUDT16 does not directly interact with 53BP1 due to the absence of key residues required for binding. Taken together, our study provides insights into the molecular mechanism underlying TIRR-mediated suppression of 53BP1-dependent DNA damage repair.

Sarcodon imbricatus polysaccharides improve mouse hematopoietic function after cyclophosphamide-induced damage via G-CSF mediated JAK2/STAT3 pathway.

Sarcodon imbricatus, a rare medicinal and edible fungus, has various pharmacological bioactivities. We investigated the effects of S. imbricatus polysaccharides (SIPS) on hematopoietic function and identified the underlying mechanisms using in vitro experiments with CHRF, K562, and bone marrow mononuclear cells (BMMNCs) and in vivo experiments with a mouse model of cyclophosphamide-induced hematopoietic dysfunction. We found that SIPS induced proliferation and differentiation of CHRF and K562 cells and upregulated the expression of hematopoietic-related proteins, including p90 ribosomal S6 kinases (RSK1p90), c-Myc, and ETS transcription factor, in the two cell lines. After 28 days of treatment, SIPS enhanced the bodyweight and thymus indices of the mice, alleviated enlargement of the spleen and liver, and contributed to the recovery of peripheral blood to normal levels. More importantly, the percentages of B lymphocytes and hematopoietic stem cells or hematopoietic progenitor cells were significantly elevated in bone marrow. Based on an antibody chip analysis and enzyme-linked immunosorbent assay, SIPS were found to successfully regulate 12 cytokines to healthy levels in serum and spleen. The cytokines included the following: interleukins 1Ra, 2, 3, 4, 5, and 6, tumor necrosis factor α, interferon-γ, granulocyte colony-stimulating factor (G-CSF) and macrophage colony-stimulating factor (M-CSF), C-C motif chemokine1, and monocyte chemoattractant protein-1. Moreover, SIPS upregulated the phosphorylation levels of janus kinase 2 (JAK2) and the signal transducer and activator of transcription 3 (STAT3) in the spleen, and similar results were validated in CHRF cells, K562 cells, and BMMNCs. The data indicate that SIPS activated the JAK2/STAT3 pathway, possibly by interactions among multiple cytokines, particularly G-CSF. We found that SIPS was remarkably beneficial to the bone marrow hematopoietic system, and we anticipate that it could improve myelosuppression induced by long-term radiotherapy or chemotherapy.

Crystal structure and biochemical features of dye-decolorizing peroxidase YfeX from Escherichia coli O157 Asp143 and Arg232 play divergent roles toward different substrates.

YfeX from Escherichia coli O157 is a bacterial dye-decolorizing peroxidase that represents both dye-decoloring activity and typical peroxidase activity. We reported the crystal structure of YfeX bound to heme at 2.09 Å resolution. The YfeX monomer resembles a ferredoxin-like fold and contains two domains. The three conserved residues surrounding the heme group are His215, Asp143 and Arg232. His215 functions as the proximal axial ligand of the heme iron atom. Biochemical data show that the catalytic significance of the conserved Asp143 and Arg232 depends on the substrate types and that YfeX may adopt various catalytic mechanisms toward divergent substrates. In addition, it is observed that an access tunnel spans from the protein molecular surface to the heme distal region, it serves as the passageway for the entrance and binding of the H2O2.

Crystal Structure of Murein-Tripeptide Amidase MpaA from Escherichia coli O157 at 2.6 Å Resolution.

Peptidoglycan (PG) is an essential component of the cell wall, and undergoes reconstruction by various PG hydrolases during cell growth, development and division. The murein- tripeptide (Mtp) amidase MpaA belongs to PG hydrolase family and is responsible for cleaving the γ-D-Glumeso- Dap amide bond in the Mtp released during PG turnover. The current paper reports the crystal structure of MpaA from Escherichia coli (E. coli) O157 at 2.6 Å resolution. The asymmetric unit consists of two protein molecules and each monomer represents the common α/ß fold of metallocarboxypeptidases (MCP). The Tyr133-Asp143 loop appears to mediate the entrance and binding of the substrate into the active groove. A structural comparison of MpaA with its homologue from Vibrio harveyi showed that MpaA has narrower active pocket entrance with a smaller surface opening, which is determined by the Val204-Thr211 loop. The reported structure provides a starting point for the molecular mechanism of MpaA in a significant human pathogen.

Crystal structure and molecular mechanism of an aspartate/glutamate racemase from Escherichia coli O157.

EcL-DER, the aspartate/glutamate racemase from the pathogen Escherichia coli O157, exhibits racemase activity for l-aspartate and l-glutamate. This study reports the crystal structures of apo-EcL-DER, the EcL-DER-l-aspartate and the EcL-DER-d-aspartate complexes. The EcL-DER structure contains two domains, forming pseudo-mirror symmetry in the active site. A unique catalytic pair consisting of Thr(83) and Cys(197) exists in the active site. The characteristic conformations of l-Asp and d-Asp in the active site provide a straight structural evidence for the racemization mechanism of EcL-DER. In addition, the diversity of catalytic pairs implies that PLP-independent amino acid racemases adopt various catalytic mechanisms and are classified into different subgroups.

Comparison of quality-of-life in tongue cancer patients undergoing tongue reconstruction with lateral upper arm free flap and radial forearm free flap.

Surgery entails radical resection, neck dissection and tongue reconstruction has been commonly used in treatment of T2 and T3 tongue squamous cell carcinoma. Although lateral upper arm free flap (LUFF) and radial forearm free flap (RFFF) are similar in texture and thickness, significant differences can be noticed in the donor-site function and surgical demands. In the treatment of T2 and T3 tongue cancer, the choice of either LUFF or RFFF is still not defined.We aim to investigatethe long-term QOL of patients with moderate tongue defect and reconstruction with LUFF or RFFF, based on which to provide clinical suggestion for tongue reconstructions.Sixty-five patients (T2 or T3 stage, 42 underwent tongue reconstruction with RFFF and 23 with LUFF) treated at the Department of Oral and Maxillofacial Surgery, Hospital of Stomatology, Sun Yat-Sen University from January 2005 to June 2009 were included. The QOL of each patient was determined using the questionnaire designed based on the University of Washington Quality-of-Life (UW-QOL, version 4). The questionnaire was accomplished by a qualified medical staff blinded to the study after telephone communication with each patient. Statistical analysis showed that no significant difference was noticed in the long-term QOL of patients with tongue cancer after tongue reconstruction using LUFF or RFFF, respectively, indicating that similar QOLs were obtained in the long-term follow-up of patients with tongue cancer (T2 or T3 stages) using LUFF and RFFF for reconstruction.