Crystal structure of prodigiosin binding protein PgbP, a GNAT family protein, in Serratia marcescens FS14.

Acetylation is a conserved modification catalyzed by acetyltransferases that play prominent roles in a large number of biological processes. Members of the general control non-repressible 5 (GCN5)-N-acetyltransferase (GNAT) protein superfamily are widespread in all kingdoms of life and are characterized by highly conserved catalytic fold, and can acetylate a wide range of substrates. Although the structures and functions of numerous eukaryotic GNATs have been identified thus far, many GNATs in microorganisms remain structurally and functionally undescribed. Here, we determined the crystal structure of the putative GCN5-N-acetyltransferase PgbP in complex with CoA in Serratia marcescens FS14. Structural analysis revealed that the PgbP dimer has two cavities, each of which binds a CoA molecule via conserved motifs of the GNAT family. In addition, the biochemical studies showed that PgbP is a prodigiosin-binding protein with high thermal stability. To our knowledge, this is the first view of GNAT binding to secondary metabolites and it is also the first report of prodigiosin binding protein. Molecular docking and mutation experiments indicated that prodigiosin binds to the substrate binding site of PgbP. The structure-function analyses presented here broaden our understanding of the multifunctionality of GNAT family members and may infer the mechanism of the multiple biological activities of prodigiosin.

CXCR3 deficiency decreases autoantibody production by inhibiting aberrant activated T follicular helper cells and B cells in lupus mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a high level of autoantibody production. T follicular helper (Tfh) cells and B cells participate in the development of SLE. Several studies have shown that CXCR3+ cells are increased in SLE patients. However, the mechanism through which CXCR3 influences lupus development remains unclear. In this study, we established lupus models to determine the role of CXCR3 in lupus pathogenesis. The concentration of autoantibodies was detected using the enzyme-linked immunosorbent assay (ELISA), and the percentages of Tfh cells and B cells were measured using flow cytometry. RNA sequencing (RNA-seq) was performed to detect the differentially expressed genes in CD4+ T cells from wild-type (WT) and CXCR3 knock-out (KO) lupus mice. Migration of CD4+ T cells in spleen section was assessed using immunofluorescence. CD4+ T cell function in helping B cells produce antibodies was determined using a co-culture experiment and supernatant IgG ELISA. Lupus mice were treated with a CXCR3 antagonist to confirm the therapeutic effects. We found that the expression of CXCR3 was increased in CD4+ T cells from lupus mice. CXCR3 deficiency reduced autoantibody production with decreased proportions of Tfh cells, germinal center (GC) B cells, and plasma cells. Expression of Tfh-related genes was downregulated in CD4+ T cells from CXCR3 KO lupus mice. Migration to B cell follicles and T-helper function of CD4+ T cells were reduced in CXCR3 KO lupus mice. CXCR3 antagonist AMG487 decreased the level of serum anti-dsDNA IgG in lupus mice. We clarify that CXCR3 may play an important role in autoantibody production by increasing the percentages of aberrant activated Tfh cells and B cells and promoting the migration and T-helper function of CD4+ T cells in lupus mice. Thus, CXCR3 may be a potential target for lupus therapy.

Insights into the wetting phenomenon induced by scaling of calcium sulfate in membrane distillation.

Development of water/wastewater treatment based on membrane distillation (MD) suffers from the drawback that the hydrophobic membrane could be wetted for various reasons. Despite significant efforts, there is uncertainty in addressing the wetting induced by scaling of calcium sulfate, which is ubiquitous and recalcitrant in MD processes. This study made the first attempt to analyze the interplay between the growing crystals and the porous structures in the framework of Stoney's equation. Optical coherence tomography (OCT) was exploited to measure the membrane shift, whereby the scaling-induced deformation was correlated with the variation in stress created in the crystal-containing layer. Along with the stress analysis, the OCT-based characterization was combined with conventional approaches to ascertain the dependence of the scaling-induced wetting on the rate of concentrating the crystallizing species when arriving at a high degree of supersaturation in the feed. This study would refine the physical picture for better understanding crystal-membrane interactions that result in not only the wetting phenomenon but also the irreversible damage of membrane structures, thereby lending itself to the development of strategies for MD-based applications with improved efficiency.

PRMT5 disruption drives antitumor immunity in cervical cancer by reprogramming T cell-mediated response and regulating PD-L1 expression.

Rationale: Protein arginine methyltransferase 5 (PRMT5) is an oncogene that promotes tumor cell proliferation, invasion and metastasis. However, the underlying mechanisms by which PRMT5 contributes to the progression of cervical cancer and especially the tumor microenvironment remain poorly understood. Methods: PRMT5 expression level was analyzed by Q-PCR, western blot, immunohistochemistry, and TCGA database. The role of PRMT5 in tumor growth was observed by transplanted tumor models, and the function of T cells in tumor microenvironment and in vitro co-culture system was investigated through flow cytometry. The transcriptional regulation of PRMT5 was analyzed using luciferase reporter and chromatin immunoprecipitation (ChIP) assay. The therapeutic effect of PRMT5 inhibitor was evaluated in a cervical cancer cell line transplanted tumor model. Results: We observed that the mRNA and protein expression levels of PRMT5 were increased in cervical cancer tissues, and the high expression of PRMT5 was associated with poor outcomes in cervical cancer patients. The absence of PRMT5 significantly inhibited tumor growth in a cervical cancer transplanted tumor model, and importantly, PRMT5 absence in tumors led to increase the number and enhance the function of tumor infiltrating T cells. Mechanistically, PRMT5 enhanced the transcription of STAT1 through symmetric dimethylation of histone H3R2 and thus promoted PD-L1 expression in cervical cancer cells. Moreover, in an in vitro co-culture system, knockdown of PRMT5 in tumor cells could directly enhance the expression of IFN-γ, TNF-α and granzyme B in T cells. These results suggested that PRMT5 promoted the development of cervical cancer by the crosstalk between tumor cells and T cells. Furthermore, the PRMT5 inhibitor EPZ015666 treatment could suppress tumor growth in a cervical cancer transplanted tumor model. Conclusion: Our results clarify a new mechanism which PRMT5 knockdown in cervical cancer cells drives an antitumor function via reprogramming T cell-mediated response and regulating PD-L1 expression. Thus, our study highlights that PRMT5 may be a potential target for cervical cancer therapy.

Micro-/nano-voids guided two-stage film cracking on bioinspired assemblies for high-performance electronics.

Current metal film-based electronics, while sensitive to external stretching, typically fail via uncontrolled cracking under a relatively small strain (~30%), which restricts their practical applications. To address this, here we report a design approach inspired by the stereocilia bundles of a cochlea that uses a hierarchical assembly of interfacial nanowires to retard penetrating cracking. This structured surface outperforms its flat counterparts in stretchability (130% versus 30% tolerable strain) and maintains high sensitivity (minimum detection of 0.005% strain) in response to external stimuli such as sounds and mechanical forces. The enlarged stretchability is attributed to the two-stage cracking process induced by the synergy of micro-voids and nano-voids. In-situ observation confirms that at low strains micro-voids between nanowire clusters guide the process of crack growth, whereas at large strains new cracks are randomly initiated from nano-voids among individual nanowires.