Polynomial algebra reveals diverging roles of the unfolded protein response in endothelial cells during ischemia–reperfusion injury

The unfolded protein response (UPR) – the endoplasmic reticulum stress response – is found in various pathologies including ischemia–reperfusion injury (IRI). However, its role during IRI is still unclear. Here, by combining two different bioinformatical methods – a method based on ordinary differential equations (Time Series Network Inference) and an algebraic method (probabilistic polynomial dynamical systems) – we identified the IRE1α–XBP1 and the ATF6 pathways as the main UPR effectors involved in cell’s adaptation to IRI. We validated these findings experimentally by assessing the impact of their knock-out and knock-down on cell survival during IRI.     

Unique properties of polyphenol stilbenes in the brain: more than direct antioxidant actions; gene/protein regulatory activity

The 'French Paradox' has been typically associated with moderate consumption of wine, especially red wine. A polyphenol 3,4',5-trihydroxy-trans-stilbene (a member of the non-flavonoids family), better known as resveratrol, has been purported to have many health benefits. A number of these valuable properties have been attributed to its intrinsic antioxidant capabilities, although the potential level of resveratrol in the circulation is likely not enough to neutralize free radical scavenging. The brain and the heart are uniquely vulnerable to hypoxic conditions and oxidative stress injuries. Recently, evidence suggests that resveratrol could act as a signaling molecule within tissues and cells to modulate the expression of genes and proteins. Stimulation of such proteins and enzymes could explain some the intracellular antioxidative properties. The modulation of genes could suffice as an explanation of some of resveratrol's cytoprotective actions, as well as its influence on blood flow, cell death, and inflammatory cascades. Resveratrol stimulation of the expression of heme oxygenase is one example. Increased heme oxygenase activity has led to significant protection against models of in vitro and in vivo oxidative stress injury. Resveratrol could provide cellular resistance against insults; although more work is necessary before it is prescribed as a potential prophylactic in models of either acute or chronic conditions, such as stroke, amyotrophic lateral sclerosis, Parkinson, Alzheimer, and a variety of age-related vascular disorders.     

Environmental factors influencing the regional distribution and local density of a small benthic fish: the stoneloach (<Emphasis Type="Italic">Barbatula barbatula</Emphasis>)

We investigated the relationships between different environmental variables and the spatial distribution patterns of the stoneloach (Barbatula barbatula) at the stream system, the stream site, and the mesohabitat (riffle/pool) scales in south-western France. Stoneloach occurred at 240 sites (out of 554 sampling sites), chiefly close to the source, in areas at low elevation and with weak slopes. Population density at a site was primarily influenced by physical conditions. Stream width was positively related to the probability of presence of stoneloach within the stream system, but negatively related to local density. These results indicate that stoneloaches can occur in a wide range of streams, but they are less abundant in wide rivers, probably because of lower habitat heterogeneity. Slope was negatively correlated to both fish presence at the regional scale and local density, suggesting that stoneloach’s swimming performance were weak under greater erosive forces. These results suggested that the distribution of populations and the density of stoneloach were governed by the suitability of physical habitat. Multi-scale studies of factors influencing a species’distribution allow to integrate patterns observed at different scales, and enhance our understanding of interactions between animals and their environment. The use of few pertinent variables in successful final models could reduce the effort and cost of data collection for water management applications.     

Anti-PrP antibodies block PrPSc replication in prion-infected cell cultures by accelerating PrPC degradation

The use of anti-PrP antibodies represents one of the most promising strategies for the treatment of prion diseases. In the present study, we screened various anti-PrP antibodies with the aim of identifying those that would block PrP(Sc) replication in prion-infected cell culture. Two antibodies, SAF34 recognizing the flexible octarepeats region on HuPrP protein, and SAF61 directed against PrP amino acid residues (144-152), not only inhibited PrP(Sc) formation in prion-infected neuroblastoma cells but also decreased the PrP(C) levels in non-infected N2a cells. In addition, treatment with both SAF34 and SAF61 antibodies decreased PrP(C) and PrP(Sc) levels in the cells synergistically. In the presence of both antibodies, our results showed that the mode of action which leads to the disappearance of PrP(Sc) in cells is directly coupled to PrP(C) degradation by reducing the half-life of the PrP(C) protein.     

X-linked mental retardation and autism are associated with a mutation in the NLGN4 gene, a member of the neuroligin family

A large French family including members affected by nonspecific X-linked mental retardation, with or without autism or pervasive developmental disorder in affected male patients, has been found to have a 2-base-pair deletion in the Neuroligin 4 gene (NLGN4) located at Xp22.33. This mutation leads to a premature stop codon in the middle of the sequence of the normal protein and is thought to suppress the transmembrane domain and sequences important for the dimerization of neuroligins that are required for proper cell-cell interaction through binding to beta-neurexins. As the neuroligins are mostly enriched at excitatory synapses, these results suggest that a defect in synaptogenesis may lead to deficits in cognitive development and communication processes. The fact that the deletion was present in both autistic and nonautistic mentally retarded males suggests that the NLGN4 gene is not only involved in autism, as previously described, but also in mental retardation, indicating that some types of autistic disorder and mental retardation may have common genetic origins.     

Characterization of a theta-replicating plasmid from Streptococcus thermophilus

Plasmids of Streptococcus thermophilus were previously classified, based on DNA homology, into at least four groups (A-D). Here, we report the characterization of plasmids of group B and D. The sequence analysis of pSMQ173b (group D) indicates that this plasmid contains 4449 bp, five open reading frames (ORFs) and replicates via the rolling-circle mechanism of the pGI3 family. The plasmid pSMQ308 (group B) contains 8144 bp and six ORFs. Two ORFs likely encode a primase/helicase and an integrase. Northern blot experiments demonstrate that these two orfs are transcribed within the three strains containing plasmids of group B. Two-dimensional agarose gel electrophoresis shows that pSMQ308 replicates via a theta mechanism. To our knowledge, this is the first report of a plasmid replicating via a theta mode in S. thermophilus. Finally, a classification of 20 sequenced S. thermophilus plasmids into six groups based on their mode of replication is proposed.     

The sequential cleavage of membrane anchored pro-EGF requires a membrane serine protease other than kallikrein in rat kidney

Epidermal growth factor (EGF) is present in kidney membranes as an integral type I precursor protein, enzymatically processed to release immunoreactive materials in urine or incubation medium. The aim of this work was the elucidation of both the anchor of the serine protease activity that processes pro-EGF, and the determination of the steps of the enzymatic processing. Quantification of EGF containing molecules by RIA following gel filtration analysis demonstrated that the membrane precursor is first shed from the kidney membrane principally into a 170-kDa soluble precursor. This entire ectodomain is further processed into a 70-kDa precursor and finally into the mature 5.9 kDa urinary EGF. These species correspond to the ones found in urines. Both shedding and maturation events are clearly realized by membrane anchored serine protease activity, which remains active in detergent. By use of wild-type and knockout mice urines, we found that tissue kallikrein (TK) was not involved in the regulation of this processing.