NLRP1 inflammasome is one of the best-characterized inflammasomes in humans and other mammals. However, the existence of this inflammasome in nonmammalian species remains poorly understood. In this study, we report the molecular and functional identification of an NLRP1 homolog, NLRP1 (NLRP1) from a zebrafish () model. This NLRP1 possesses similar structural architecture to mammalian NLRP1s. It can trigger the formation of a classical inflammasome for the activation of zebrafish inflammatory caspases ( Caspase [Caspase]-A and Caspase-B) and maturation of IL-1β in a ASC (ASC)-dependent manner. In this process, NLRP1 promotes the aggregation ofASC into a filament with ASC core and ASC cluster. The assembly of NLRP1 inflammasome depends on the CARD-CARD homotypic interaction betweenNLRP1 and ASC core, and PYD-PYD interaction between Caspase-A/B andASC cluster. The FIIND domain in NLRP1 is necessary for inflammasome assembly. To understand the mechanism of how the twoCaspases are coordinated in NLRP1 inflammasome, we propose a two-step sequential activation model. In this model, the recruitment and activation ofCaspase-A/B in the inflammasome is shown in an alternate manner, with a preference for Caspase-A followed by a subsequent selection forCaspase-B. By using morpholino oligonucleotide-based knockdown assays, the NLRP1 inflammasome was verified to play important functional roles in antibacterial innate immunity in vivo. These observations demonstrate that the NLRP1 inflammasome originated as early as in teleost fish. This finding not only gives insights into the evolutionary history of inflammasomes but also provides a favorable animal model for the study of NLRP1 inflammasome-mediated immunology and diseases.

BackgroundThe main cause of death in patients with non‐small cell lung cancer (NSCLC) is the progression of cancer metastasis, which can be attributed to multiple factors, such as cancer stem cells (CSCs) and epithelial‐mesenchymal transition (EMT). Long non‐coding RNAs (lncRNAs) play important roles in the regulation of the cell cycle, cell proliferation, immune responses, and metastasis in cancers, but the potential roles and mechanisms of lincRNAs in CSC‐like properties of cancer have not yet been elucidated.MethodsHuman NSCLC cell lines (A549 and H1299), highly metastatic cell lines (L9981 and 95D), and their corresponding low‐metastatic cell lines (NL9980 and 95C) were subject to quantitative real‐time PCR and Western blot, transwell invasion, colony formation, and wound healing assays.ResultsLinc‐ITGB1 was greatly upregulated in CSC spheres. Linc‐ITGB1 knockdown markedly inhibited CSC formation and the expression of stemness‐associated genes, such as Sox2, Nanog, Oct‐4, c‐Myc, and CD133. Depletion of linc‐ITGB1 expression also inhibited the in vitro invasive and migratory potential of cells, and further analysis indicated that linc‐ITGB1 knockdown increased the expression of the epithelial marker E‐cadherin and downregulated the mesenchymal markers vimentin and fibronectin. The EMT‐related transcription factor Snail mediated these effects of linc‐ITGB1 in NSCLC, and overexpression of Snail significantly reversed the inhibitory effects of linc‐ITGB1 depletion.ConclusionOverall, our study demonstrated that linc‐ITGB1 promoted NSCLC cell EMT and cancer stemness by regulating Snail expression.

BackgroundIn an effort to reconstitute the NAD+ synthetic pathway in Escherichia coli (E. coli), we produced a set of gene knockout mutants with deficiencies in previously well-defined NAD+de novo and salvage pathways. Unexpectedly, the mutant deficient in NAD+de novo and salvage pathway I could grow in M9/nicotinamide medium, which was contradictory to the proposed classic NAD+ metabolism of E. coli. Such E. coli mutagenesis assay suggested the presence of an undefined machinery to feed nicotinamide into the NAD+ biosynthesis. We wanted to verify whether xanthosine phophorylase (xapA) contributed to a new NAD+ salvage pathway from nicotinamide.ResultsAdditional knockout of xapA further slowed down the bacterial growth in M9/nicotinamide medium, whereas the complementation of xapA restored the growth phenotype. To further validate the new function of xapA, we cloned and expressed E. coli xapA as a recombinant soluble protein. Biochemical assay confirmed that xapA was capable of using nicotinamide as a substrate for nicotinamide riboside formation.ConclusionsBoth the genetic and biochemical evidences indicated that xapA could convert nicotinamide to nicotinamide riboside in E. coli, albeit with relatively weak activity, indicating that xapA may contribute to a second NAD+ salvage pathway from nicotinamide. We speculate that this xapA-mediated NAD+ salvage pathway might be significant in some bacteria lacking NAD+de novo and NAD+ salvage pathway I or II, to not only use nicotinamide riboside, but also nicotinamide as precursors to synthesize NAD+. However, this speculation needs to be experimentally tested.

Peroxiredoxin (Prx) was previously known as a Cys-dependent thioredoxin. However, we unexpectedly observed that Prx1 from the green spotted puffer fish Tetraodon nigroviridis (TnPrx1) was able to reduce H2O2 in a manner independent of Cys peroxidation and reductants. This study aimed to validate a novel function for Prx1, delineate the biochemical features and explore its antioxidant role in cells. We have confirmed that Prx1 from the puffer fish and humans truly possesses a catalase (CAT)-like activity that is independent of Cys residues and reductants, but dependent on iron. We have identified that the GVL motif was essential to the CAT-like activity of Prx1, but not to the Cys-dependent thioredoxin peroxidase (POX) activity, and generated mutants lacking POX and/or CAT-like activities for individual functional validation. We discovered that the TnPrx1 POX and CAT-like activities possessed different kinetic features in the reduction of H2O2. The overexpression of wild-type TnPrx1 and mutants differentially regulated the intracellular levels of reactive oxygen species (ROS) and the phosphorylation of p38 in HEK-293T cells treated with H2O2. Prx1 is a dual-function enzyme by acting as POX and CAT with varied affinities towards ROS. This study extends our knowledge on Prx1 and provides new opportunities to further study the biological roles of this family of antioxidants.

Background Basic medical laboratory courses (BMLCs) play an essential role in medical education and offer several benefits to students. Although various student-centered and active learning strategies have been increasingly incorporated into medical education, their applications in BMLCs are limited. This paper aimed to explore the educational effects of a flipped classroom (FC) combined with team-based learning (TBL) strategy in BMLCs at Zhejiang University School of Medicine. Methods Four hundred eight 3rd-Year medical students were assigned to either the FC-TBL group (n = 235) or the FC group (n = 173) to complete three experiments on the respiration block of BMLCs. The two groups’ immediate and long-term academic performance were compared, and the FC-TBL students’ perceptions of different instructional strategies were surveyed. Results Students in the FC-TBL group scored higher on the immediate post-tests after class and higher on the final exams in two of the three experiment sessions. They preferred FC-TBL to FC for its higher engagement, more feedback, and better learning environment. Students felt the FC with TBL blended instructional strategy stimulated their interest in learning and deep thinking. Conclusions Compared with the FC group, students in the FC-TBL group improved academic performance and had a more positive experience overall. Our findings support the feasibility and advantage of the flipped classroom with team-based learning as a blended learning strategy in the BMLC curriculum.