Spherical nucleic acids with tailored DNA conformation via bromide backfilling for the detection of kanamycin.

The improper conformation of oligonucleotides on gold nanoparticle surfaces is caused by unintended base adsorption, which hinders DNA hybridization and lowers colloidal stability. In this work, we treated spherical nucleic acids with Br- , which serves as an efficient backfilling agent, to adjust the DNA conformation by displacing bases from the gold surface. To investigate the effect of DNA conformation on interfacial recognition, a kanamycin fluorescent aptasensor was constructed with bromide backfilled-treated spherical nucleic acids. In the presence of kanamycin, the anchored aptamer binds with the target and the partially complementary reporter strand is dissociated from the surface of the gold nanoparticles, resulting in the fluorescence recovery of labelled fluorophore on the reporter strand. Under optimum conditions, the apparent binding affinity of the aptasensor with bromide backfilling was 2.2-fold that without backfilled one. The proposed aptasensor exhibited a good liner relationship between the concentration of kanamycin and fluorescence intensity change in the range 200 nM to 10 µM and the limit of detection was calculated to be 71.53 nM. Moreover, this aptasensor was also successfully applied in a spiked milk sample assay and the satisfactory recoveries were obtained in the range 96.94-101.57%, which demonstrated its potential in practical applications.

Author Correction: Bromodomain protein Brd3 promotes Ifnb1 transcription via enhancing IRF3/p300 complex formation and recruitment to Ifnb1 promoter in macrophages.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Polycomb chromobox Cbx2 enhances antiviral innate immunity by promoting Jmjd3-mediated demethylation of H3K27 at the Ifnb promoter.

Polycomb chromobox (CBX) proteins regulate gene transcription by maintaining chromatin states, which guide a variety of biological processes. Now, epigenetic regulation of innate immune response is an emerging field. However, the role of CBX proteins in innate immunity remains unclear. We confirmed that the expression of CBX family proteins, especially Cbx2, was decreased in macrophages upon viral infection, and then we investigated the role of Cbx2 in the antiviral immune response. Silencing or knockdown of Cbx2 in macrophages inhibited virus-induced production of IFN-ß. Furthermore, heterozygous Cbx2 knockout were susceptible to VSV challenge. Mechanistically, Cbx2 binds to and recruits Jmjd3 to the Ifnb promoter, leading to demethylation of H3K27me3 and increased transcription of IFN-ß. Together, our study reveals a non-traditional function of a Cbx protein and adds new insight into the epigenetic regulation of antiviral innate immunity.

[KAT6B promotes LPS-triggered IL-6 production via enhancing recruitment of H3K23 acetylation to IL-6 promoter region].

Objective To explore the regulatory role of lysine acetyltransferase 6B (KAT6B) in lipopolysaccharide(LPS)-triggered interleukin 6 (IL-6) production in macrophages and the mechanism. Methods Real-time quantitative PCR (qRT-PCR) was performed to detect and quantitate KAT6B mRNA level in mouse peritoneal macrophages and RAW264.7 cells under LPS stimulation for 0, 2, 4, 6 hours. RNA interference technology was used to knock down the expression of KAT6B in peritoneal macrophages, the expression of IL-6 in LPS-stimulated murine macrophages was detected by qRT-PCR at the mRNA level and ELISA at the protein level; meanwhile, the levels of IL-6 mRNA and protein were tested by the same means in RAW264.7 cells with over-expressed KAT6B. The transfection efficiency and signal pathway activation were examined by Western blot analysis. Dual-luciferase reporter assay was used to investigate the role of KAT6B in IL-6 transcription. Chromatin immunoprecipitation (ChIP) was done to evaluate the effect of KAT6B on the recruitment of acetylation of histone 3 lysine 23 (H3K23ac) within IL-6 promoter region. Results LPS stimulation up-regulated KAT6B expression in both peritoneal macrophages and RAW264.7 cells. Silence of KAT6B suppressed LPS-induced IL-6 production in murine peritoneal macrophages, overexpression of V5-KAT6B promoted the production of LPS-triggered IL-6 in RAW264.7 cells. The change of KAT6B level did not affect the activity of NF-κBp65 and MAPK induced by LPS. KAT6B increased the recruitment of H3K23ac on IL-6 gene DNA promoter. Conclusion KAT6B can enhance LPS-triggered IL-6 production by promoting the recruitment of H3K23ac to IL-6 gene promoter region.

Bromodomain protein Brd3 promotes Ifnb1 transcription via enhancing IRF3/p300 complex formation and recruitment to Ifnb1 promoter in macrophages.

As members of bromodomain and extra-terminal motif protein family, bromodomain-containing proteins regulate a wide range of biological processes including protein scaffolding, mitosis, cell cycle progression and transcriptional regulation. The function of these bromodomain proteins (Brds) in innate immune response has been reported but the role of Brd3 remains unclear. Here we find that virus infection significantly downregulate Brd3 expression in macrophages and Brd3 knockout inhibits virus-triggered IFN-ß production. Brd3 interacts with both IRF3 and p300, increases p300-mediated acetylation of IRF3, and enhances the association of IRF3 with p300 upon virus infection. Importantly, Brd3 promotes the recruitment of IRF3/p300 complex to the promoter of Ifnb1, and increases the acetylation of histone3/histone4 within the Ifnb1 promoter, leading to the enhancement of type I interferon production. Therefore, our work indicated that Brd3 may act as a coactivator in IRF3/p300 transcriptional activation of Ifnb1 and provided new epigenetic mechanistic insight into the efficient activation of the innate immune response.

[Brd3 promotes IL-6 production via enhancing acetylase CBP recruitment and histone 3 acetylation within IL6 promoter].

Objective To investigate the role of bromodomain containing 3 (Brd3) in LPS-triggered interleukin-6 (IL-6) production in macrophages and the underlying mechanism. Methods CRISPR-Cas9 technology was used to screen an RAW264.7 cell line with Brd3 knockout (Brd3-/-). The Brd3-/- cells were used as an experimental group, and the parential cells expressing wide-type Brd3 as a control group. The IL-6 level in cell culture supernatant was detected by ELISA after 100 ng/mL LPS challenging. Effect of Brd3 knockout on the expression and activation of signal pathways involved in IL-6 expression, including the NF-κB and mitogen-activated protein kinase (MAPK) pathways were examined by Western blot analysis. Chromatin immunoprecipitation (ChIP) assay was used to evaluate the recruitment of acetylase CREB-binding protein (CBP) to IL6 gene promoter and the acetylation level of histone 3 within IL6 gene promoter. Results LPS treatment significantly downregulated Brd3 expression in mouse peritoneal macrophages. LPS-induced production of IL-6 was significantly inhibited in Brd3-/- macrophages. The expressions and activation of signal molecules within NF-κB and MAPK pathways were barely affected. Brd3 knockout significantly decreased the recruitment of acetylase CBP to IL6 gene promoter, and the acetylation level of histone3 within IL6 gene promoter was also repressed. Conclusion Brd3 promotes LPS-triggered IL-6 production via promoting the recruitment of CBP to IL6 promoter and enhancing the acetylation level of histone 3 within IL6 promoter.

Crystal structure of 1,1'-bis-(2-meth-oxy-carbonyl-2-methyl-prop-yl)ferrocene.

The Fe atom in the title ferrocene derivative, [Fe(C11H15O2)2], is situated on an inversion centre. As a result of the point-group symmetry -1 of the mol-ecule, the ferrocene moiety adopts a staggered conformation. The average Fe-C(Cp) bond length (Cp is cyclo-penta-dien-yl) is 2.045 (4) Å, in agreement with that of other disubstituted ferrocenes. The Fe-C bond length involving the substituted C atom is slightly longer [2.0521 (17) Å] than the remaining Fe-C bond lengths caused by the inductive effect of the methyl-ene group on the Cp ring. Apart from van der Waals forces, no significant inter-molecular inter-actions are observed in the crystal packing.