Macrophage-stimulating protein polymorphism rs3197999 is associated with a gain of function: implications for inflammatory bowel disease

Crohn's disease and ulcerative colitis, the two main types of inflammatory bowel disease (IBD), were reported to be associated with a variety of genetic polymorphisms. A subset of these polymorphisms was identified in both diseases and only three of them were found in primary sclerosing cholangitis (PSC). rs3197999 (Arg689Cys) located in the MST1 gene is one of the most convincingly replicated IBD/PSC-associated polymorphisms but its functional consequences have not been investigated, yet. We expressed both MST1 gene variants (Arg(689) (MSP(wt)) and Cys(689) (MSP(mut)) in a eukaryotic cell system and compared their stimulatory effects on macrophage-like THP-1 cells. Except for the rate of apoptosis that remained unchanged, MSP(mut) significantly increased the stimulatory effect of MSP (macrophage-stimulating protein) on chemotaxis and proliferation by THP-1 cells, indicating a gain of function associated with the Arg689Cys exchange. A broad set of evidence reported previously suggests that pro-inflammatory changes in macrophage function have a major role in the initiation of the inflammatory process in IBD and PSC. Therefore, the gain of function observed with rs3197999 in MST1 might provide a cellular mechanism for the consistent association of this polymorphism with an increased risk for IBD and PSC.     

Multi-element stable isotope analysis of H,C, N and S in hair and nails of contemporary human remains

This paper presents a comparison of the isotopic ratios of hydrogen, carbon, nitrogen and sulphur of three pairings of hair and nail tissue taken from contemporary human remains. Our aim was to examine the possibility of a direct comparison of isotopic data in hair with that of nail tissue for forensic purposes. The results indicate that stable isotope ratios of the elements were best comparable between human scalp hair longer than 3 cm and the distal end of the nails. There were no distinct variations between finger and toenails. Our isotopic data for bulk hair and nail confirmed that hair samples were slightly enriched in ¹³C but depleted in ¹⁵N compared to nail samples. Furthermore, our data reveal that δ³⁴S values in nail samples were more variable than in hair samples. Direct comparison of the corresponding segments of hair and nail samples may be difficult due to individual differences especially for δ¹⁵N and δ²H. Hair may have an isotopic composition more consistent with the ingested food within a specific time than is provided by nail. It can be concluded that once a hair is formed, no further metabolic changes of the isotopic pattern should occur. Nevertheless, our data suggest that there was a change in isotope ratios particularly for δ²H along the hair shaft. Interpretation of the isotope data in corresponding segments of hair and nail for forensic purposes must consider particular variations, especially for chronological considerations.     

MinD-like ATPase FlhG effects location and number of bacterial flagella during C-ring assembly

The number and location of flagella, bacterial organelles of locomotion, are species specific and appear in regular patterns that represent one of the earliest taxonomic criteria in microbiology. However, the mechanisms that reproducibly establish these patterns during each round of cell division are poorly understood. FlhG (previously YlxH) is a major determinant for a variety of flagellation patterns. Here, we show that FlhG is a structural homolog of the ATPase MinD, which serves in cell-division site determination. Like MinD, FlhG forms homodimers that are dependent on ATP and lipids. It interacts with a complex of the flagellar C-ring proteins FliM and FliY (also FliN) in the Gram-positive, peritrichous-flagellated Bacillus subtilis and the Gram-negative, polar-flagellated Shewanella putrefaciens. FlhG interacts with FliM/FliY in a nucleotide-independent manner and activates FliM/FliY to assemble with the C-ring protein FliG in vitro. FlhG-driven assembly of the FliM/FliY/FliG complex is strongly enhanced by ATP and lipids. The protein shows a highly dynamic subcellular distribution between cytoplasm and flagellar basal bodies, suggesting that FlhG effects flagellar location and number during assembly of the C-ring. We describe the molecular evolution of a MinD-like ATPase into a flagellation pattern effector and suggest that the underappreciated structural diversity of the C-ring proteins might contribute to the formation of different flagellation patterns.Most bacteria move by flagella. The flagellar architecture is conserved and can be divided into the cytoplasmic C-ring, the basal body, the rod, and the exterior hook and filament structures (1). Bacterial species differ in the number and arrangement of their flagella (flagellation pattern) (2). However, the mechanisms that allow bacteria to establish their specific flagellation patterns reproducibly during each cell division are poorly understood. The protein FlhG (also known as “YlxH,” “MinD2,” “FleN,” or “MotR”) is essential for the correct flagellation pattern of polar- (3–5), lophotrichous- (6), amphitrichous- (7), and peritrichous-flagellated bacteria (8, 9). Deletion of flhG in polar-flagellated bacteria leads to hyperflagellation and impaired motility (3–5). In the amphitrichous-flagellated Campylobacter jejuni, ∼40% of the cells of a ΔflhG strain exhibited more than one flagellum at one pole and were impaired in motility (7). The peritrichous-flagellated bacterium Bacillus subtilis exhibits ∼26 flagellar basal bodies arranged symmetrically around midcell in a gridlike pattern (8). Furthermore, flagella are discouraged at the cell pole. Deletion of flhG does not result in swimming or swarming defects, although multiple flagella appear in tufts from constrained loci on the cell, and flagellar basal bodies often are aggregated (8). FlhG acts in concert with the signal recognition particle (SRP)-GTPase FlhF (10–14) that recruits the flagellar protein FliF to the cell pole in the polar-flagellated Vibrio cholerae (15). FlhG is predicted to belong to the MinD/ParA ATPase family (6, 16) whose characterized members act in orchestrated spatiotemporal processes (e.g., cell-division site determination and plasmid/chromosome partitioning (summarized in ref. 17). Together with MinC, MinD constitutes the conserved center of the Min system which regulates bacterial cell division by restricting cytokinetic Z-ring assembly to midcell (reviewed in ref. 18). MinD forms ATP-dependent homodimers (19) that interact with the inner membrane through a C-terminal amphipathic helix (membrane-targeting sequence, MTS) (20, 21). By this mechanism, MinD recruits MinC to the membrane where MinC inhibits polymerization of FtsZ into the Z-ring (22). Interestingly, Campylobacter jejuni does not contain a Min system, and FlhG is involved in flagellation pattern control and regulation of cell division (7). In contrast to MinD, the molecular framework in which the putative MinD-like ATPase FlhG controls flagellation is unknown. Also, it is enigmatic how conserved homologs of FlhG can control different flagellation patterns in different species. Here, we investigated the mechanism and function of FlhG in the Gram-positive, peritrichous-flagellated B. subtilis (Bs) and the Gram-negative, polar-flagellated Shewanella putrefaciens (Sp).     

Acid-induced structural changes in human rhinovirus 14: possible role in uncoating.

X-ray diffraction data were collected from human rhinovirus 14 crystals a few minutes after exposure to acid vapor and prior to excessive crystalline disorder. Conformational changes occurred (i) in the GH loop of viral protein (VP) 1, (ii) at the ion binding site on the outer surface of the pentamer center, and (iii) in VP3 and VP4 on the virion's interior in the vicinity of the fivefold axis. Amino acid substitutions in mutants resistant to low pH, or to drugs that inhibit uncoating, were concentrated in the vicinity of the GH loop. It is proposed that the acid-induced changes reflect processes that trigger uncoating.     

Detection of antigen in the coelomocytes of the earthworm, Eisenia foetida (Annelida).

Earthworms, Eisenia foetida, are able to respond to antigenic stimulation by the formation of the antigen-binding molecules by coelomocytes--the effector cells of annelids' defence reactions. The ability to react with gold-labelled antigen was detected in agranular coelomocytes by electron microscopy. Furthermore, flow cytometry analysis used for quantitative evaluation of antigen binding showed significant increase of both antigen-binding cells and the amount of antigen bound per cell after stimulation. The antigen binding was inhibited by preincubation of cells with several similar proteins, although the most potent inhibitor was the immunizing antigen.     

Erythrocytapheresis for Plasmodium falciparum infection complicated by cerebral malaria and hyperparasitemia

In malaria due to Plasmodium falciparum, life-threatening complications are in part related to the degree of parasitemia. Whole blood exchange and red blood cell exchange (RCE) have been used for the rapid removal of parasites from the circulation of patients with a high parasite load complicated by cerebral, pulmonary, and renal dysfunction. We have treated three 5-45-year-old patients with hyperparasitemia and end-organ dysfunction with red cell exchange by automated apheresis as an adjunct to specific anti-malarial chemotherapy. Parasitemia dropped more than 80% in all three patients immediately after the exchange, and all patients had an uneventful and full recovery. In combination with effective anti-malarial chemotherapy, apheresis RCE is a safe and rapid approach to treat complicated malaria due to P. falciparum.     

Colorectal carcinogenesis in germ-free and conventionally reared rats: different intestinal environments affect the systemic immunity

Intestinal microbiota are considered to play an important role both in colorectal tumor development and in the modulation of mucosal immunity. Studies on animals reared in germ-free (GF, without intestinal microbiota) versus conventional (CV, with regular microbiota colonization of the bowel) conditions can aid in clarifying the influence of bacteria on carcinogenesis and the anticancer immune response. The capability of the intestinal environment to modulate anticancer immunity not only at the mucosal but also at the systemic level is still an open question. In our study we found that, following the same protocol of colorectal cancer induction, GF rats developed less and smaller tumors than CV rats. The GF rats that did not develop cancer also presented a better anticancer immune response with an increase in NK, NKT, CTL, B cells and cytotoxicity in peripheral blood. We hypothesize that the lower antigenic challenge and the absence of the 'physiological inflammation', caused by the commensal microbiota in the gut of CV rats, may enhance the capability of the GF rats to develop more efficacious anticancer immune responses. The different levels of tolerance/regulatory mechanisms in GF versus the CV animals may modulate the anticancer response not only at the mucosal but also at the systemic immunity level.