Large nucleotide-dependent conformational change in Rab28

AbstractRab GTPases are essential regulators of membrane trafficking. We report crystal structures of Rab28 in the active (GppNHp-bound) and inactive (GDP-3′P-bound) forms at 1.5 and 1.1Å resolution. Rab28 is a distant member of the Rab family. While the overall fold of Rab28 resembles that of other Rab GTPases, it undergoes a larger nucleotide-dependent conformational change than other members of this family. Added flexibility resulting from a double-glycine motif at the beginning of switch 2 might partially account for this observation. The double-glycine motif, which is conserved in the Arf family, only occurs in Rab28 and Rab7B of the Rab family, and may have a profound effect on their catalytic activities

Transcriptomic Profiling and Cellular Composition of Creeping Fat in Crohn's disease

Background and Aims: Creeping fat [CF] is a poorly understood feature of Crohn's disease [CD], characterized by the wrapping of mesenteric adipose tissue [MAT] around the inflamed intestine. The aim of this study was to investigate the transcriptional profile and compositional features of CF. Methods: We collected 59 MAT samples: 23 paired samples from patients with CD (CF [CD-CF] and MAT around the uninflamed intestine [CD-MAT]) and 13 MAT samples from non-CD patients [Con-MAT]. Differentially expressed gene [DEG], functional pathway, cell deconvolution, and gene co-expression network analyses were performed. Results: By comparing three different MAT samples, we identified a total of 529 DEGs [|log(2)FoldChange| > 1.5; false discovery rate < 0.05]. Of these, 323 genes showed an incremental pattern from Con-MAT to CD-MAT, and to CD-CF, while 105 genes displayed a decremental pattern. Genes with an incremental pattern were related to immune cell responses, including B- andT-cell activation, while genes with a decremental pattern were involved in cell trafficking and migration. Cell deconvolution analysis revealed significant changes in cellular composition between the CD-CF and Con-MAT groups, with increased proportions of B-cells/plasma cells [p = 1.16 x 10(-4)], T-cells [p = 3.66 x 10(-3)], and mononuclear phagocytes [p = 3.53 x 10(-2)] in the CD-CF group. In contrast, only the B-cell/plasma cell component showed a significant increase [p = 1.62 x 10(-2)] in the CD-MAT group compared to Con-MAT. Conclusion: The distinct transcriptional profiles and altered cellular components of each MAT found in our study provide insight into the mechanisms behind CF and highlight its possible role in the pathogenesis of CD.N

Synergistic Effect of Detection and Separation for Pathogen Using Magnetic Clusters

Early diagnosis of infectious diseases is important for treatment; therefore, selective and rapid detection of pathogenic bacteria is essential for human health. We report a strategy for highly selective detection and rapid separation of pathogenic microorganisms using magnetic nanoparticle clusters. Our approach to develop probes for pathogenic bacteria, including Salmonella, is based on a theoretically optimized model for the size of clustered magnetic nanoparticles. The clusters were modified to provide enhanced aqueous solubility and versatile conjugation sites for antibody immobilization. The clusters with the desired magnetic property were then prepared at critical micelle concentration (CMC) by evaporation-induced self-assembly (EISA). Two different types of target-specific antibodies for H- and O-antigens were incorporated on the cluster surface for selective binding to biological compartments of the flagella and cell body, respectively. For the two different specific binding properties, Salmonella were effectively captured with the O-antibody-coated polysorbate 80-coated magnetic nanoclusters (PCMNCs). The synergistic effect of combining selective targeting and the clustered magnetic probe leads to both selective and rapid detection of infectious pathogens