Biomarker discovery in asthma‐related inflammation and remodeling

Asthma is a complex inflammatory disease of airways. A network of reciprocal interactions between inflammatory cells, peptidic mediators, extracellular matrix components, and proteases is thought to be involved in the installation and maintenance of asthma‐related airway inflammation and remodeling. To date, new proteic mediators displaying significant activity in the pathophysiology of asthma are still to be unveiled. The main objective of this study was to uncover potential target proteins by using surface‐enhanced laser desorption/ionization‐time of flight‐mass spectrometry (SELDI‐TOF‐MS) on lung samples from mouse models of allergen‐induced airway inflammation and remodeling. In this model, we pointed out several protein or peptide peaks that were preferentially expressed in diseased mice as compared to controls. We report the identification of different five proteins: found inflammatory zone 1 or RELMα (FIZZ‐1), calcyclin (S100A6), clara cell secretory protein 10 (CC10), Ubiquitin, and Histone H4.     

Loss of TBL1XR1 Disrupts Glucocorticoid Receptor Recruitment to Chromatin and Results in Glucocorticoid Resistance in a B-Lymphoblastic Leukemia Model

Although great advances have been made in the treatment of pediatric acute lymphoblastic leukemia, up to one of five patients will relapse, and their prognosis thereafter is dismal. We have previously identified recurrent deletions in TBL1XR1, which encodes for an F-box like protein responsible for regulating the nuclear hormone repressor complex stability. Here we model TBL1XR1 deletions in B-precursor ALL cell lines and show that TBL1XR1 knockdown results in reduced glucocorticoid receptor recruitment to glucocorticoid responsive genes and ultimately decreased glucocorticoid signaling caused by increased levels of nuclear hormone repressor 1 and HDAC3. Reduction in glucocorticoid signaling in TBL1XR1-depleted lines resulted in resistance to glucocorticoid agonists, but not to other chemotherapeutic agents. Importantly, we show that treatment with the HDAC inhibitor SAHA restores sensitivity to prednisolone in TBL1XR1-depleted cells. Altogether, our data indicate that loss of TBL1XR1 is a novel driver of glucocorticoid resistance in ALL and that epigenetic therapy may have future application in restoring drug sensitivity at relapse.     

Shade tolerance,canopy gaps and mechanisms of coexistence of forest trees

The belief that canopy gaps are important for the maintenance of tree species diversity appears to be widespread, but there have been no formal theoretical models to assess under what conditions gap phase processes allow coexistence. Much of the empirical research on niche differentiation in response to gaps has focused on evidence for an interspecific tradeoff between low light survival and high light growth. The objectives of this study are first to distinguish the possible mechanisms allowing coexistence based on this tradeoff, and second, to explore their limitations. We present a theory of forest dynamics driven by small‐scale disturbances as a special case of the theory of coexistence in variable environments. We demonstrate that temporal and spatial heterogeneity in light conditions that results from canopy gaps can allow stable coexistence as a result of three previously documented general mechanisms: ‘relative non‐linearity’, ‘the successional niche’ and the ‘storage effect’. We find that temporal fluctuations in light availability alone allow the stable coexistence of only two species. Spatial variation in disturbance synchronicity and intensity allows three species to coexist in a narrow parameter space. The rate of extinction is, however, extremely slow and there is transient coexistence of a larger number of species for a long period of time. We conclude that while the low light survival/high light growth tradeoff may be ubiquitous in forest tree species, it is unlikely to function as an important mechanism for the stable coexistence of several tree species.     

French Experience of 2009 A/H1N1v Influenza in Pregnant Women

Background

The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France.

Methodology/Principal Findings

A national registry was created to screen pregnant women with laboratory-confirmed 2009 A/H1N1v influenza. Three hundred and fifteen patients from 46 French hospitals were included: 40 patients were admitted to intensive care units (severe outcomes), 111 were hospitalized in obstetric or medical wards (moderate outcomes), and 164 were outpatients (mild outcomes). The 2009 A/H1N1v influenza illness occurred during all pregnancy trimesters, but most women (54%), notably the severe patients (70%), were in the third trimester. Among the severe patients, twenty (50%) underwent mechanical ventilation, and eleven (28%) were treated with extracorporeal membrane oxygenation. Three women died from A/H1N1v influenza. We found a strong association between the development of a severe outcome and both co-existing illnesses (adjusted odds ratio [OR], 5.1; 95% confidence interval [CI], 2.2–11.8) and a delay in oseltamivir treatment after the onset of symptoms (>3 or 5 days) (adjusted OR, 4.8; 95% CI, 1.9–12.1 and 61.2, 95% CI; 14.4–261.3, respectively). Among the 140 deliveries after 22 weeks of gestation known to date, 19 neonates (14%) were admitted to a neonatal intensive care unit, mainly for preterm delivery, and two neonates died. None of these neonates developed 2009 A/H1N1v infection.

Conclusions

This series confirms the high incidence of complications in pregnant women infected with pandemic A/H1N1v observed in other countries but depicts a lower overall maternal and neonatal mortality and morbidity than indicated in the USA or Australia. Moreover, our data demonstrate the benefit of early oseltamivir treatment in this specific population.     

Distinct functions of maternal and somatic Pat1 protein paralogs

We previously identified Xenopus Pat1a (P100) as a member of the maternal CPEB RNP complex, whose components resemble those of P-(rocessing) bodies, and which is implicated in translational control in Xenopus oocytes. Database searches have identified Pat1a proteins in other vertebrates, as well as paralogous Pat1b proteins. Here we characterize Pat1 proteins, which have no readily discernable sequence features, in Xenopus oocytes, eggs, and early embryos and in human tissue culture cells. xPat1a and 1b have essentially mutually exclusive expression patterns in oogenesis and embryogenesis. xPat1a is degraded during meiotic maturation, via PEST-like regions, while xPat1b mRNA is translationally activated at GVBD by cytoplasmic polyadenylation. Pat1 proteins bind RNA in vitro, via a central domain, with a preference for G-rich sequences, including the NRAS 5′ UTR G-quadruplex-forming sequence. When tethered to reporter mRNA, both Pat proteins repress translation in oocytes. Indeed, both epitope-tagged proteins interact with the same components of the CPEB RNP complex, including CPEB, Xp54, eIF4E1b, Rap55B, and ePAB. However, examining endogenous protein interactions, we find that in oocytes only xPat1a is a bona fide component of the CPEB RNP, and that xPat1b resides in a separate large complex. In tissue culture cells, hPat1b localizes to P-bodies, while mPat1a-GFP is either found weakly in P-bodies or disperses P-bodies in a dominant-negative fashion. Altogether we conclude that Pat1a and Pat1b proteins have distinct functions, mediated in separate complexes. Pat1a is a translational repressor in oocytes in a CPEB-containing complex, and Pat1b is a component of P-bodies in somatic cells.     

Structures of sortase B from Staphylococcus aureus and Bacillus anthracis reveal catalytic amino acid triad in the active site

Surface proteins attached by sortases to the cell wall envelope of bacterial pathogens play important roles during infection. Sorting and attachment of these proteins is directed by C-terminal signals. Sortase B of S. aureus recognizes a motif NPQTN, cleaves the polypeptide after the Thr residue, and attaches the protein to pentaglycine cross-bridges. Sortase B of B. anthracis is thought to recognize the NPKTG motif, and attaches surface proteins to m-diaminopimelic acid cross-bridges. We have determined crystal structure of sortase B from B. anthracis and S. aureus at 1.6 and 2.0 A resolutions, respectively. These structures show a beta-barrel fold with alpha-helical elements on its outside, a structure thus far exclusive to the sortase family. A putative active site located on the edge of the beta-barrel is comprised of a Cys-His-Asp catalytic triad and presumably faces the bacterial cell surface. A putative binding site for the sorting signal is located nearby.     

Real-time flow cytometry analysis of permeability transition in isolated mitochondria

Mitochondrial membrane permeabilization (MMP) is a key event in necrotic and (intrinsic) apoptotic processes. MMP is controlled by a few major rate-limiting events, one of which is opening of the permeability transition pore (PTP). Here we develop a flow cytometry (FC)-based approach to screen and study inducers and blockers of MMP in isolated mitochondria. Fixed-time and real-time FC permits to co-evaluate and order modifications of mitochondrial size, structure and inner membrane (IM) electrochemical potential (DeltaPsi(m)) during MMP. Calcium, a major PTP opener, and alamethicin, a PTP-independent MMP inducer, trigger significant mitochondrial forward scatter (FSC) increase and side scatter (SSC) decrease, correlating with spectrophotometrically detected swelling. FC-based fluorescence detection of the DeltaPsi(m)-sensitive cationic lipophilic dye JC-1 permits to detect DeltaPsi(m) variations induced by PTP openers or specific inducers of inner MMP such as carbonylcyanide m-chlorophenylhydrazone (mClCCP). These simple, highly sensitive and quantitative FC-based methods will be pertinent to evaluate compounds for their ability to control MMP.     

Spectrum of phenylketonuria mutations in Western Europe and North Africa,and their relation to polymorphic DNA haplotypes at the phenylalanine hydroxylase locus

Summary A total of 252 chromosomes from 126 patients with phenylalanine hydroxylase (PAH) deficiencies were analyzed for both mutant genotypes and restriction fragment length polymorphism (RFLP) haplotypes at the PAH locus. The mutant genes studied originated either from Western Europe (116 alleles) or from Mediterranean countries (136 alleles). Only 27% of all mutant alleles were found to carry identified mutations, particularly mutations at codon 252 (2.3%), 261 (7.5%), 280 (6.3%), 408 (3.5%) and at the splice donor site of intron 12 (6.3%). The mutant genotypes were associated with RFLP haplotypes 7, 1, 38, 2 and 3 at the PAH locus respectively. Except for the splice mutation of intron 12, these associations were preferential, but not exclusive, since the other four mutations were found on the background of at least two RFLP haplotypes. These results, together with the observation that 85% of PAH deficient patients are heterozygotes for their mutant genotypes, emphasize the great heterogeneity of PAH deficiencies in Mediterranean countries and hamper systematic DNA testing for carrier status in this population.     

Heterogeneity and Convergence of Olfactory First-Order Neurons Account for the High Speed and Sensitivity of Second-Order Neurons

In the olfactory system of male moths, a specialized subset of neurons detects and processes the main component of the sex pheromone emitted by females. It is composed of several thousand first-order olfactory receptor neurons (ORNs), all expressing the same pheromone receptor, that contact synaptically a few tens of second-order projection neurons (PNs) within a single restricted brain area. The functional simplicity of this system makes it a favorable model for studying the factors that contribute to its exquisite sensitivity and speed. Sensory information—primarily the identity and intensity of the stimulus—is encoded as the firing rate of the action potentials, and possibly as the latency of the neuron response. We found that over all their dynamic range, PNs respond with a shorter latency and a higher firing rate than most ORNs. Modelling showed that the increased sensitivity of PNs can be explained by the ORN-to-PN convergent architecture alone, whereas their faster response also requires cell-to-cell heterogeneity of the ORN population. So, far from being detrimental to signal detection, the ORN heterogeneity is exploited by PNs, and results in two different schemes of population coding based either on the response of a few extreme neurons (latency) or on the average response of many (firing rate). Moreover, ORN-to-PN transformations are linear for latency and nonlinear for firing rate, suggesting that latency could be involved in concentration-invariant coding of the pheromone blend and that sensitivity at low concentrations is achieved at the expense of precise encoding at high concentrations.     

Highly Significant Association between Two Common Single Nucleotide Polymorphisms in CORIN Gene and Preeclampsia in Caucasian Women

Preeclampsia is a frequent medical complication during pregnancy. Corin, a serine protease which activates pro-atrial natriuretic peptide, has recently been shown to be involved in the pathophysiology of preeclampsia. The aim of this study was to search for CORIN gene variations and their association to preeclampsia in Caucasian and African women. Our study population was composed of 571 pregnant women (295 with preeclampsia and 276 normotensive controls) matched for maternal and gestational age, and ethnic origin. The 22 exons of the CORIN gene were sequenced in a discovery sample (n = 260), where 31 single nucleotide polymorphisms were identified. In a replication sample (n = 311), 4 single nucleotide polymorphisms were tested. Two minor alleles (C for rs2271036 and G for rs2271037) were significantly associated to preeclampsia. Adjusted odds ratios [95% confidence interval] were 2.5 [1.2–3.8] (p = 0.007) and 2.3 [1.5–3.5] (p = 1.3×10⁻⁴), respectively. These associations were ethnic-specific, as only found in the Caucasian of subjects (odds ratio = 3.5 [1.8–6.6], p = 1.1×10⁻⁴; odds ratio = 3.1 [1.7–5.8], p = 2.1×10⁻⁴, for each single nucleotide polymorphism, respectively). The two single nucleotide polymorphisms are in almost perfect linkage disequilibrium (r² = 0.93). No specific association was found with severe preeclampsia, early-onset preeclampsia nor fetal growth retardation. In conclusion, this is the first report of a highly significant association between these two single nucleotide polymorphisms in CORIN gene and preeclampsia. Our findings further support the probability of a critical role of corin in preeclamspia pathophysiology at the uteroplacental interface.