Dopant-Dependent Toxicity of CeO2 Nanoparticles Is Associated with Dynamic Changes in H3K4me3 and H3K27me3 and Transcriptional Activation of NRF2 Gene in HaCaT Human Keratinocytes.

Despite advances in the preparation of metal oxide (MO) nanoparticles (NPs) as catalysts for various applications, concerns about the biosafety of these particles remain. In this study, we prepared transition metal-doped cerium oxide (TM@CeO2; TM = Cr, Mn, Fe, Co, or Ni) nanoparticles and investigated the mechanism underlying dopant-dependent toxicity in HaCaT human keratinocytes. We show that doping with Cr or Co but not Fe, Mn, or Ni increased the toxicity of CeO2 NPs in dose- and time-dependent manners and led to apoptotic cell death. Interestingly, while both undoped and transition metal-doped NPs increased intracellular reactive oxygen species (ROS), toxic Cr@CeO2 and Co@CeO2 NPs failed to induce the expression of NRF2 (nuclear factor erythroid 2-related factor 2) as well as its downstream target genes involved in the antioxidant defense system. Moreover, activation of NRF2 transcription was correlated with dynamic changes in H3K4me3 and H3K27me3 at the promoter of NRF2, which was not observed in cells exposed to Cr@CeO2 NPs. Furthermore, exposure to relatively non-toxic Fe@CeO2 NPs, but not the toxic Cr@CeO2 NPs, resulted in increased binding of MLL1 complex, a major histone lysine methylase mediating trimethylation of histone H3 lysine 4, at the NRF2 promoter. Taken together, our findings strongly suggest that failure of cells to respond to oxidative stress is critical for dopant-dependent toxicity of CeO2 NPs and emphasize that careful evaluation of newly developed NPs should be preceded before industrial or biomedical applications.

The chaperone Hsp90 and PPIases of the cyclophilin and FKBP families facilitate membrane translocation of Photorhabdus luminescens†ADP-ribosyltransferases.

TccC3 and TccC5 from Photorhabdus luminescens are ADP-ribosyltransferases, which modify actin and Rho GTPases, respectively, thereby inducing polymerization and clustering of actin. The bacterial proteins are components of the Photorhabdus toxin complexes, consisting of the binding and translocation component TcdA1, a proposed linker component TcdB2 and the enzymatic component TccC3/5. While the action of the toxins on target proteins is clearly defined, uptake and translocation of the toxins into the cytosol of target cells are not well understood. Here we show by using pharmacological inhibitors that heat shock protein 90 (Hsp90) and peptidyl prolyl cis/trans isomerases (PPIases) including cyclophilins and FK506-binding proteins (FKBPs) facilitate the uptake of the ADP-ribosylating toxins into the host cell cytosol. Inhibition of Hsp90 and/or PPIases resulted in decreased intoxication of target cells by Photorhabdus toxin complexes determined by cell rounding and reduction of transepithelial electrical resistance of cell monolayers. ADP-ribosyltransferase activity of toxins and toxin-induced pore formation were notimpaired by the inhibitors of Hsp90 and PPIases. The Photorhabdus toxins interacted with Hsp90, FKBP51, Cyp40 and CypA, suggesting a role of these host cell factors in translocation and/or refolding of the ADP-ribosyltransferases.

Enhancer-promoter specificity in gene transcription: molecular mechanisms and disease associations.

Although often located at a distance from their target gene promoters, enhancers are the primary genomic determinants of temporal and spatial transcriptional specificity in metazoans. Since the discovery of the first enhancer element in simian virus 40, there has been substantial interest in unraveling the mechanism(s) by which enhancers communicate with their partner promoters to ensure proper gene expression. These research efforts have benefited considerably from the application of increasingly sophisticated sequencing- and imaging-based approaches in conjunction with innovative (epi)genome-editing technologies; however, despite various proposed models, the principles of enhancer-promoter interaction have still not been fully elucidated. In this review, we provide an overview of recent progress in the eukaryotic gene transcription field pertaining to enhancer-promoter specificity. A better understanding of the mechanistic basis of lineage- and context-dependent enhancer-promoter engagement, along with the continued identification of functional enhancers, will provide key insights into the spatiotemporal control of gene expression that can reveal therapeutic opportunities for a range of enhancer-related diseases.

Transcriptional and Epigenetic Regulation of Context-Dependent Plasticity in T-Helper Lineages.

Th cell lineage determination and functional specialization are tightly linked to the activation of lineage-determining transcription factors (TFs) that bind cis-regulatory elements. These lineage-determining TFs act in concert with multiple layers of transcriptional regulators to alter the epigenetic landscape, including DNA methylation, histone modification and three-dimensional chromosome architecture, in order to facilitate the specific Th gene expression programs that allow for phenotypic diversification. Accumulating evidence indicates that Th cell differentiation is not as rigid as classically held; rather, extensive phenotypic plasticity is an inherent feature of T cell lineages. Recent studies have begun to uncover the epigenetic programs that mechanistically govern T cell subset specification and immunological memory. Advances in next generation sequencing technologies have allowed global transcriptomic and epigenomic interrogation of CD4+ Th cells that extends previous findings focusing on individual loci. In this review, we provide an overview of recent genome-wide insights into the transcriptional and epigenetic regulation of CD4+ T cell-mediated adaptive immunity and discuss the implications for disease as well as immunotherapies.

3D bioprinted vascularized lung cancer organoid models with underlying disease capable of more precise drug evaluation.

Despite encouraging progress in the development ofin vitrocancer models,in vitrocancer models that simultaneously recapitulate the complexity of the tumor microenvironment and its diverse cellular components and genetic properties remain lacking. Here, an advanced vascularized lung cancer (LC) model is proposed, which includes patient-derived LC organoids (LCOs), lung fibroblasts, and perfusable vessels using 3D bioprinting technology. To better recapitulate the biochemical composition of native lung tissues, a porcine lung-derived decellularized extracellular matrix (LudECM) hydrogel was produced to offer physical and biochemical cues to cells in the LC microenvironment. In particular, idiopathic pulmonary fibrosis-derived lung fibroblasts were used to implement fibrotic niches similar to actual human fibrosis. It was shown that they increased cell proliferation and the expression of drug resistance-related genes in LCOs with fibrosis. In addition, changes in resistance to sensitizing targeted anti-cancer drugs in LCOs with fibrosis were significantly greater in LudECM than in that Matrigel. Therefore, assessment of drug responsiveness in vascularized LC models that recapitulate lung fibrosis can help determine the appropriate therapy for LC patients accompanied by fibrosis. Furthermore, it is expected that this approach could be utilized for the development of targeted therapies or the identification of biomarkers for LC patients accompanied by fibrosis.

Dynamics of Viral and Host 3D Genome Structure upon Infection.

Eukaryotic chromatin is highly organized in the 3D nuclear space and dynamically regulated in response to environmental stimuli. This genomic organization is arranged in a hierarchical fashion to support various cellular functions, including transcriptional regulation of gene expression. Like other host cellular mechanisms, viral pathogens utilize and modulate host chromatin architecture and its regulatory machinery to control features of their life cycle, such as lytic versus latent status. Combined with previous research focusing on individual loci, recent global genomic studies employing conformational assays coupled with high-throughput sequencing technology have informed models for host and, in some cases, viral 3D chromosomal structure re-organization during infection and the contribution of these alterations to virus-mediated diseases. Here, we review recent discoveries and progress in host and viral chromatin structural dynamics during infection, focusing on a subset of DNA (human herpesviruses and HPV) as well as RNA (HIV, influenza virus and SARS-CoV-2) viruses. An understanding of how host and viral genomic structure affect gene expression in both contexts and ultimately viral pathogenesis can facilitate the development of novel therapeutic strategies.

Characteristics of Perovskite Solar Cells According to Thickness of Doped ZnGa2O4 Down-Converting Thin Film.

A ZnGa2O4:Eu3+ layer was deposited on the incident surface of a perovskite solar cell (PSC) to convert ultraviolet rays into current within the solar cell. The ZnGa2O4:Eu3+ layer was deposited using the sol-gel method, and the thickness of the film was controlled using the number of spin coatings. When the coating was applied six times, a layer with almost no oscillation due to reflection was fabricated. It was confirmed that the efficiency of the PSC was not adversely affected by the coating. In addition, generation of a current by converting ultraviolet radiation within the solar cell was confirmed.

Combined chemical and physical transformation method with RbCl and sepiolite for the transformation of various bacterial species.

DNA transformation that delivers plasmid DNAs into bacterial cells is fundamental in genetic manipulation to engineer and study bacteria. Developed transformation methods to date are optimized to specific bacterial species for high efficiency. Thus, there is always a demand for simple and species-independent transformation methods. We herein describe the development of a chemico-physical transformation method that combines a rubidium chloride (RbCl)-based chemical method and sepiolite-based physical method, and report its use for the simple and efficient delivery of DNA into various bacterial species. Using this method, the best transformation efficiency for Escherichia coli DH5α was 4.3×106CFU/µg of pUC19 plasmid, which is higher than or comparable to the reported transformation efficiencies to date. This method also allowed the introduction of plasmid DNAs into Bacillus subtilis (5.7×103CFU/µg of pSEVA3b67Rb), Bacillus megaterium (2.5×103CFU/µg of pSPAsp-hp), Lactococcus lactis subsp. lactis (1.0×102CFU/µg of pTRKH3-ermGFP), and Lactococcus lactis subsp. cremoris (2.2×102CFU/µg of pMSP3535VA). Remarkably, even when the conventional chemical and physical methods failed to generate transformed cells in Bacillus sp. and Enterococcus faecalis, E. malodoratus and E. mundtii, our combined method showed a significant transformation efficiency (2.4×104, 4.5×102, 2×101, and 0.5×101CFU/µg of plasmid DNA). Based on our results, we anticipate that our simple and efficient transformation method should prove usefulness for introducing DNA into various bacterial species without complicated optimization of parameters affecting DNA entry into the cell.

Fabrication of FGF-2 immobilized electrospun gelatin nanofibers for tissue engineering.

Conjugated gelatin nanofibers were fabricated by electrospinning, followed by a simple glutaraldehyde cross-linking procedure and avidin conjugation. Then, biotinylated growth factors were immobilized onto the surface of the fibers through avidin-biotin covalent binding. The immobilization of growth factors was confirmed through immunostaining using fluorescence microscopy and microplate spectrophotometry. Adipose derived stem cells (ASCs) were cultured to examine the effect of immobilized growth factors on cell proliferation using the cell counting Kit-8 (CCK-8) assay. Gelatin nanofibers with no growth factors attached and growth factors in suspension within media were used as controls. Growth factors were successfully immobilized onto the surface, in amounts corresponding to the concentrations applied, and increased cell proliferation to a higher extend than growth factors in suspension. Our results suggest that this controllable scaffolding strategy provides an effective system for growth factors delivery in tissues, suitable for engineering applications.