Pulmonary microRNA profiling in a mouse model of ventilator-induced lung injury

The aim of this study was to investigate the changes induced by high tidal volume ventilation (HVTV) in pulmonary expression of micro-RNAs (miRNAs) and identify potential target genes and corresponding miRNA-gene networks. Using a real-time RT-PCR-based array in RNA samples from lungs of mice subjected to HVTV for 1 or 4 h and control mice, we identified 65 miRNAs whose expression changed more than twofold upon HVTV. An inflammatory and a TGF-β-signaling miRNA-gene network were identified by in silico pathway analysis being at highest statistical significance (P = 10(-43) and P = 10(-28), respectively). In the inflammatory network, IL-6 and SOCS-1, regulated by miRNAs let-7 and miR-155, respectively, appeared as central nodes. In TGF-β-signaling network, SMAD-4, regulated by miR-146, appeared as a central node. The contribution of miRNAs to the development of lung injury was evaluated in mice subjected to HVTV treated with a precursor or antagonist of miR-21, a miRNA highly upregulated by HVTV. Lung compliance was preserved only in mice treated with anti-miR-21 but not in mice treated with pre-miR-21 or negative-control miRNA. Both alveolar-arterial oxygen difference and protein levels in bronchoalveolar lavage were lower in mice treated with anti-miR-21 than in mice treated with pre-miR-21 or negative-control miRNA (D(A-a): 66 ± 27 vs. 131 ± 22, 144 ± 10 mmHg, respectively, P < 0.001; protein concentration: 1.1 ± 0.2 vs. 2.3 ± 1, 2.1 ± 0.4 mg/ml, respectively, P < 0.01). Our results show that HVTV induces changes in miRNA expression in mouse lungs. Modulation of miRNA expression can affect the development of HVTV-induced lung injury.     

Differential expression of two small Hsps during diapause in the corn stalk borer Sesamia nonagrioides (Lef.)

We isolated and characterized two members of the α-crystallin/sHsp family, SnoHsp19.5 and SnoHsp20.8 from Sesamia nonagrioides (Lepidoptera: Noctuidae). The cDNAs encoded proteins of 174 and 185 amino acids, with calculated molecular weights of 19.5 and 20.8 kDa, respectively. The deduced amino acid sequences of SnoHsp19.5 and SnoHsp20.8 showed highest homology to Hsp19.7 of Mamestra brassicae and to Bombyx mori Hsp20.4, respectively. Expression patterns of SnoHsp19.5 and SnoHsp20.8 in non-diapausing individuals under different environmental conditions (heat or cold) showed different accumulation profiles for the two genes after heat and cold treatment. SnoHsp19.5 was consistently expressed, while SnoHsp20.8 gene was down-regulated in deep diapause and was up-regulated at the termination of diapause. Our results suggest that these two genes play distinctive roles in the regulation of diapause.     

D2-receptor-linked signaling pathways regulate the expression of hepatic CYP2E1

This study investigated the role of catecholamine-related signaling pathways in the regulation of hepatic cytochrome P450 (CYP2E1). Central and peripheral catecholamine depletion with reserpine down-regulated CYP2E1. On the other hand, selective peripheral catecholamine depletion with guanethidine increased CYP2E1 apoprotein levels. Enrichment of peripheral catecholamines with adrenaline suppressed p-nitrophenol hydroxylase activity (PNP). PNP activity was also markedly suppressed by l-DOPA. Stimulation of D(2)-receptors with bromocriptine up-regulated CYP2E1, as assessed by enzyme activity and protein levels, whereas blockade of D(2)-dopaminergic receptors with sulpiride down-regulated this isozyme. These findings indicate that central and peripheral catecholamines have different effects on CYP2E1. Central catecholamines appear related to the up-regulation, whereas the role of peripheral catecholamines is clearly related to the type and location of adrenoceptors involved. D(2)-receptor-linked signaling pathways have an up-regulating effect on CYP2E1, while D(1)-receptor pathways may down-regulate this isozyme. It is worth noting that the widespread environmental pollutant benzo(alpha)pyrene (B(alpha)P) altered the modulating effect of catecholaminergic systems on CYP2E1 regulation. In particular, whereas stimulation or blockade of adrenoceptors had no effect on constitutive PNP activity, exposure to B(alpha)P modified the impact of central and peripheral catecholamines and alpha(2)-adrenoceptors on CYP2E1 expression. It appears that under the influence of B(alpha)P, alpha(2)-adrenergic receptor-linked signaling pathways increased CYP2E1 apoprotein levels. Given that a wide range of xenobiotics and clinically used drugs are activated by CYP2E1 to toxic metabolites, including the production of reactive oxygen species (ROS), it is possible that therapies challenging dopaminergic receptor- and/or alpha(2)-adrenoceptor-linked signaling pathways may alter the expression of CYP2E1, thus affecting the progress and development of several pathologies.     

HP1-β is required for development of the cerebral neocortex and neuromuscular junctions

HP1 proteins are thought to be modulators of chromatin organization in all mammals, yet their exact physiological function remains unknown. In a first attempt to elucidate the function of these proteins in vivo, we disrupted the murine Cbx1 gene, which encodes the HP1-β isotype, and show that the Cbx1^−/−-null mutation leads to perinatal lethality. The newborn mice succumbed to acute respiratory failure, whose likely cause is the defective development of neuromuscular junctions within the endplate of the diaphragm. We also observe aberrant cerebral cortex development in Cbx1^−/− mutant brains, which have reduced proliferation of neuronal precursors, widespread cell death, and edema. In vitro cultures of neurospheres from Cbx1^−/− mutant brains reveal a dramatic genomic instability. Our results demonstrate that HP1 proteins are not functionally redundant and that they are likely to regulate lineage-specific changes in heterochromatin organization.     

Shared parameter models under random effects misspecification

A common objective in longitudinal studies is the investigationof the association structure between a longitudinal responseprocess and the time to an event of interest. An attractiveparadigm for the joint modelling of longitudinal and survivalprocesses is the shared parameter framework, where a set ofrandom effects is assumed to induce their interdependence. Inthis work, we propose an alternative parameterization for sharedparameter models and investigate the effect of misspecifyingthe random effects distribution in the parameter estimates andtheir standard errors.     

Conformational Analysis of the Thrombin Receptor Agonist Peptides SFLLR and SFLLR-NH2 by NMR: Evidence for a Cyclic Bioactive Conformation

The conformational properties of the pentapeptide Ser-Phe-Leu-Leu-Arg (P5), a human thrombin receptor-derived sequence forming part of a tethered ligand which activates the thrombin receptor, and its more active amide derivative Ser-Phe-Leu-Leu-Arg-NH₂ (P5-NH₂), have been studied by proton NMR spectroscopy in dimethylsulfoxide. Measurements of nuclear Overhauser effects, performed using two-dimensional rotating frame nuclear Overhauser (ROESY) and one-dimensional nuclear Overhauser enhancement (NOE) spectroscopy, revealed that P5 exists mainly in an extended conformation. However, proton–proton 1D-NOEs between Phe CH and Ser CH, Leu³ CH and Leu³ NH, and Leu⁴ CH and Leu⁴ NH, as well as between the Ser and Arg sidechains, also implicated a minor conformer for P5 having a curved backbone and a near-cyclic structure. In contrast to P5, measurements of NOEs and ROEs for P5-NH₂ revealed a more stabilized cyclic structure which may account for its higher biological potency. Thus strong interresidue sequential NH (i)–NH (i + 1) interactions, as well as C-terminal carboxamide to N-terminal side-chain interactions, i.e., Arg CONH₂ to Phe ring and Arg CONH₂ to Ser , observed at lower levels of the ROESY spectrum, supported a curved backbone structure for SFLLR-NH₂. Since the higher potaency P5-NH₂ analogue adopts predominantly a cyclic structure, a cyclic bioactive conformation for thrombin receptor agonist peptides is suggested.     

Structure and mode of action of the membrane-permeabilizing antimicrobial peptide pheromone plantaricin A

The three-dimensional structure in dodecyl phosphocholine micelles of the 26-mer membrane-permeabilizing bacteriocin-like pheromone plantaricin A (PlnA) has been determined by use of nuclear magnetic resonance spectroscopy. The peptide was unstructured in water but became partly structured upon exposure to micelles. An amphiphilic alpha-helix stretching from residue 12 to 21 (possibly also including residues 22 and 23) was then formed in the C-terminal part of the peptide, whereas the N-terminal part remained largely unstructured. PlnA exerted its membrane-permeabilizing antimicrobial activity through a nonchiral interaction with the target cell membrane because the d-enantiomeric form had the same activity as the natural l-form. This nonchiral interaction involved the amphiphilic alpha-helical region in the C-terminal half of PlnA because a 17-mer fragment that contains the amphiphilic alpha-helical part of the peptide had antimicrobial potency that was similar to that of the l- and d-enantiomeric forms of PlnA. Also the pheromone activity of PlnA depended on this nonchiral interaction because both the l- and d-enantiomeric forms of the 17-mer fragment inhibited the pheromone activity. The pheromone activity also involved, however, a chiral interaction between the N-terminal part of PlnA and its receptor because high concentrations of the l-form (but not the d-form) of a 5-mer fragment derived from the N-terminal part of PlnA had pheromone activity. The results thus reveal a novel mechanism whereby peptide pheromones such as PlnA may function. An initial nonchiral interaction with membrane lipids induces alpha-helical structuring in a segment of the peptide pheromone. The peptide becomes thereby sufficiently structured and properly positioned in the membrane interface, thus enabling it to engage in a chiral interaction with its receptor in or near the membrane water interface. This membrane-interacting mode of action explains why some peptide pheromones/hormones such as PlnA sometimes display antimicrobial activity in addition to their pheromone activity.     

Evaluation of the prebiotic potential of arabinoxylans extracted from wheat distillers’ dried grains with solubles (DDGS) and in-process samples

Applied Microbiology and Biotechnology - Distillers’ dried grains with solubles (DDGS) is a low-value agro-industrial by-product, rich in arabinoxylans (AX), which is produced by commercial...