Unconventional autophagy mediated by the WD40 domain of ATG16L1 is derailed by the T300A Crohn disease risk polymorphism

A coding polymorphism of the critical autophagic effector ATG16L1 (T300A) increases the risk of Crohn disease, but how this mutation influences the function of ATG16L1 has remained unclear. In a recent report, we showed that the A300 allele alters the ability of the C-terminal WD40 domain of ATG16L1 to interact with proteins containing a specific amino acid motif able to recognize this region. This defect impairs the capacity of the motif-containing transmembrane molecule TMEM59 to induce the unconventional autophagic labeling of the same single-membrane vesicles where this protein is located. Such alteration derails the intracellular trafficking of TMEM59 and the xenophagic response against bacterial infection. In contrast, canonical autophagy remains unaffected in the presence of ATG16L1^T300A. These data argue that the T300A polymorphism impairs the unconventional autophagic activities carried out by the WD40 domain, a region of ATG16L1 whose function has remained poorly understood.     

Restoring phylogenetic diversity through facilitation

Phylogenetic diversity enhances ecosystem functioning but restoration ecology has not taken advantage of this knowledge. We propose plant facilitation as a mechanism to promote phylogenetic diversity in restoration practices. We planted three functionally different species (Gypsophila struthium, Sedum album, and Limonium sucronicum) in a degraded gypsum ecosystem in Spain and found that after 7 years, the species with nurse traits (G. struthium) survived longer and facilitated the establishment of new species forming phylogenetically diverse neighborhoods. These facilitation‐driven phylodiverse communities may potentially produce a cascade of benefits on ecosystem functioning.     

Independent Candidate Serum Protein Biomarkers of Response to Adalimumab and to Infliximab in Rheumatoid Arthritis: An Exploratory Study

Response to treatment of rheumatoid arthritis shows large inter-individual variability. This heterogeneity is observed with all the anti-rheumatic drugs, including the commonly used TNF inhibitors. It seems that drug-specific and target-specific factors lead individual patients to respond or not to a given drug, although this point has been challenged. The search of biomarkers distinguishing responders from non-responders has included shotgun proteomics of serum, as a previous study of response to infliximab, an anti-TNF antibody. Here, we have used the same study design and technology to search biomarkers of response to a different anti-TNF antibody, adalimumab, and we have compared the results obtained for the two anti-TNF drugs. Search of biomarkers of response to adalimumab included depletion of the most abundant serum proteins, 8-plex isobaric tag for relative and absolute quantitation (iTRAQ) labeling, two-dimensional liquid chromatography fractionation and relative quantification with a hybrid Orbitrap mass spectrometer. With this approach, 264 proteins were identified in all the samples with at least 2 peptides and 95% confidence. Nine proteins showed differences between non-responders and responders (P < 0.05), representing putative biomarkers of response to adalimumab. These results were compared with the previous study of infliximab. Surprisingly, the non-responder/responder differences in the two studies were not correlated (r_s = 0.07; P = 0.40). This overall independence with all the proteins showed two identifiable components. On one side, the putative biomarkers of response to either adalimumab or infliximab, which were not shared and showed an inverse correlation (r_s = -0.69; P = 0.0023). On the other, eight proteins showing significant non-responder/responder differences in the analysis combining data of response to the two drugs. These results identify new putative biomarkers of response to treatment of rheumatoid arthritis and indicate that they are notably drug-specific.     

Ca2+-Independent Release of Glutamate During In Vitro Anoxia in Isolated Nerve Terminals

The effects of in vitro anoxia on the release of glutamate in isolated nerve terminals were studied. The extra-synaptosomal concentration of glutamate ([Glu]ext) under aerobic conditions was 2.3 microM and increased to 4.9 microM after 10 min of anoxia. However, when synaptosomes were incubated in the presence of lactate plus pyruvate instead of glucose, to prevent anaerobic glycolysis, anoxia induced an eightfold increase in the [Glu]ext. The accumulation of glutamate in the external medium during anoxia was Ca2+ independent and insensitive to a significant reduction of the Ca(2+)-dependent release of the amino acid. These results indicate that a Ca(2+)-independent efflux of cytoplasmic glutamate occurs during in vitro anoxia in isolated nerve terminals.     

Modification of glucose and glutamine metabolism in hybridoma cells through metabolic engineering

The present work describes the genetic modification of a hybridoma cell line with the aim to change its metabolic behaviour, particularly reducing the amounts of ammonia and lactate produced by the cells. The cellular excretion of ammonia was eliminated by transfection of a cloned glutamine synthetase gene. The metabolic characterisation of the transformed cell line includes the analysis of the changes introduced in its intracellular metabolic fluxes by means of a stoichiometric model. Furthermore, the reduction of lactate accumulation was attempted through an antisense mRNA approach, aiming to generate a rate limiting step in the glycolytic pathway, thus lowering the glucose consumption rate. The physiological results obtained with the transformed cells are discussed. A maximum reduction of about 47% in the glucose consumption rate was obtained for one of the transformations. However a main drawback was the lack of stability of the transformed cells This revised version was published online in July 2006 with corrections to the Cover Date.     

The structure and stereochemistry of artemin

Artemin was isolated from the aerial part of Artemisia maritima. Its structure and stereochemistry were determined on the basis of chemical transformations and spectral evidence     

Identification of the lipopolysaccharide O‐antigen biosynthesis priming enzyme and the O‐antigen ligase in Myxococcus xanthus: critical role of LPS O‐antigen in motility and development

Myxococcus xanthus is a model bacterium to study social behavior. At the cellular level, the different social behaviors of M. xanthus involve extensive cell–cell contacts. Here, we used bioinformatics, genetics, heterologous expression and biochemical experiments to identify and characterize the key enzymes in M. xanthus implicated in O‐antigen and lipopolysaccharide (LPS) biosynthesis and examined the role of LPS O‐antigen in M. xanthus social behaviors. We identified WbaP_Mx (MXAN_2922) as the polyisoprenyl‐phosphate hexose‐1‐phosphate transferase responsible for priming O‐antigen synthesis. In heterologous expression experiments, WbaP_Mx complemented a Salmonella enterica mutant lacking the endogenous WbaP that primes O‐antigen synthesis, indicating that WbaP_Mx transfers galactose‐1‐P to undecaprenyl‐phosphate. We also identified WaaL_Mx (MXAN_2919), as the O‐antigen ligase that joins O‐antigen to lipid A‐core. Our data also support the previous suggestion that Wzm_Mx (MXAN_4622) and Wzt_Mx (MXAN_4623) form the Wzm/Wzt ABC transporter. We show that mutations that block different steps in LPS O‐antigen synthesis can cause pleiotropic phenotypes. Also, using a wbaP_Mx deletion mutant, we revisited the role of LPS O‐antigen and demonstrate that it is important for gliding motility, conditionally important for type IV pili‐dependent motility and required to complete the developmental program leading to the formation of spore‐filled fruiting bodies.