Chaperone protein 14-3-3 and protein kinase A increase the relative abundance of low agonist sensitivity human alpha 4 beta 2 nicotinic acetylcholine receptors in Xenopus oocytes

Alpha4 and beta2 nicotinic acetylcholine (nACh) receptor subunits expressed heterologously in Xenopus oocytes assemble into a mixture of receptors with high and low agonist sensitivity whose relative abundance is influenced by the heteropentamer subunit ratio. We have found that inhibition of protein kinase A by KT5720 decreased maximal [3H]cytisine binding and acetylcholine (ACh)-induced current responses, and increased the relative proportion of alpha4beta2 receptors with high agonist sensitivity. Mutation of serine 467, a putative protein kinase A substrate in a chaperone protein binding motif within the large cytoplasmic domain of the alpha4 subunit, to alanine or asparate decreased or increased, respectively, maximal [3H]cytisine binding and ACh response amplitude. Expression of alpha4S467A mutant subunits decreased steady levels of alpha4 and the relative proportion of alpha4beta2 receptors with low agonist sensitivity, whilst expression of alpha4S467D increased steady levels of alpha4 and alpha4beta2 receptors with low agonist sensitivity. Difopein, an inhibitor of chaperone 14-3-3 proteins, decreased [3H]cytisine binding and ACh responses and increased the proportion of alpha4beta2 with high sensitivity to activation by ACh. Thus, post-translational modification affecting steady-state levels of alpha4 subunits provides a possible means for physiologically relevant, chaperone-mediated variation in the relative proportion of high and low agonist sensitivity alpha4beta2 nACh receptors.     

Antibody Complementarity-Determining Regions (CDRs): A Bridge between Adaptive and Innate Immunity

Background

It has been documented that, independently from the specificity of the native antibody (Ab) for a given antigen (Ag), complementarity determining regions (CDR)-related peptides may display differential antimicrobial, antiviral and antitumor activities.

Methodology/Principal Findings

In this study we demonstrate that a synthetic peptide with sequence identical to V_HCDR3 of a mouse monoclonal Ab (mAb) specific for difucosyl human blood group A is easily taken up by macrophages with subsequent stimulation of: i) proinflammatory cytokine production; ii) PI3K-Akt pathway and iii) TLR-4 expression. Significantly, V_HCDR3 exerts therapeutic effect against systemic candidiasis without possessing direct candidacidal properties.

Conclusions/Significance

These results open a new scenario about the possibility that, beyond the half life of immunoglobulins, Ab fragments may effectively influence the antiinfective cellular immune response in a way reminiscent of regulatory peptides of innate immunity.     

Antiviral activity of benzimidazole derivatives. II. Antiviral activity of 2-phenylbenzimidazole derivatives

Seventy-six 2-phenylbenzimidazole derivatives were synthesized and evaluated in cell-based assays for cytotoxicity and antiviral activity against a panel of 10 RNA and DNA viruses. The most commonly affected viruses were, in decreasing order, CVB-2, BVDV, Sb-1, HSV-1, and YFV, while HIV-1 and VSV were not affected, and RSV, VV and Reo-1 were only susceptible to a few compounds. Thirty-nine compounds exhibited high activity (EC₅₀ = 0.1–10 μM) against at least one virus, and four of them were outstanding for their high and selective activity against VV (24, EC₅₀ = 0.1 μM) and BVDV (50, 51, and 53 with EC₅₀ = 1.5, 0.8, and 1.0 μM, respectively). The last compounds inhibited at low micromolar concentrations the NS5B RdRp of BVDV and also of HCV, the latter sharing structural similarity with the former. The considered compounds represent attractive leads for the development of antiviral agents against poxviruses, pestiviruses and even HCV, which are important human and veterinary pathogens.     

Protein expression changes induced in murine peritoneal macrophages by Group B Streptococcus

Protein expression changes induced in thioglycolate‐elicited peritoneal murine macrophages (MΦ) by infection with type III Group B Streptococcus (GBS) are described. Proteins from control MΦ and MΦ incubated 2 h with live or heat‐inactivated GBS were separated by 2‐DE. Proteins whose expression was significantly different in infected MΦ, as compared with control cells, were identified by MS/MS analysis. Changes in the expression level of proteins involved in both positive and negative modulation of phagocytic functions, stress response and cell death were induced in MΦ by GBS infection. In particular, expression of enzymes playing a key role in production of reactive oxygen species was lowered in GBS‐infected MΦ. Significant alterations in the expression of some metabolic enzymes were also observed, most of the glycolytic and of the pentose‐cycle enzymes being down‐regulated in MΦ infected with live GBS. Finally, evidence was obtained that GBS infection affects the expression of enzymes or enzyme subunits involved in ATP synthesis and in adenine nucleotides interconversion processes.     

Synthesis and biological evaluation of new active For‐Met‐Leu‐Phe‐OMe analogues containing para‐substituted Phe residues

In the present study, we report synthesis and biological evaluation of the N‐Boc‐protected tripeptides 4a–l and N‐For protected tripeptides 5a–l as new For‐Met‐Leu‐Phe‐OMe (fMLF‐OMe) analogues. All the new ligands are characterized by the C‐terminal Phe residue variously substituted at position 4 of the aromatic ring. The agonism of 5a–l and the antagonism of 4a–l (chemotaxis, superoxide anion production, lysozyme release as well as receptor binding affinity) have been examined on human neutrophils. No synthesized compounds has higher activity than the standard fMLF‐OMe tripeptide to stimulate chemotaxis, although compounds 5a and 5c with ‐CH₃ and ‐C(CH₃)₃, respectively, in position 4 on the aromatic ring, are better than the standard tripeptide to stimulate the production of superoxide anion, in higher concentration. Compounds 4f and 4i , containing ‐F and ‐I in position 4, respectively, on the aromatic ring of phenylalanine, exhibit significant chemotactic antagonism. The influence of the different substitution at the position 4 on the aromatic ring of phenylalanine is discussed. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.     

Synthesis and evaluation of new endomorphin analogues modified at the Pro2 residue

Six new endomorphin analogues, incorporating constrained amino acids in place of native proline have been synthesized. Residues of (S)-azetidine-2-carboxylic acid (Aze), 3,4-dehydro-(S)-proline (Δ³Pro), azetidine-3-carboxylic acid (3Aze) and dehydro-alanine (ΔAla) have been used to prepare [Δ³Pro²]EM-2 (1), [Aze²]EM-1 (2), [Aze²]EM-2 (3), [3Aze²]EM-1 (4), [3Aze²]EM-2 (5) and [ΔAla²]EM-2 (6). Binding assays and functional bioactivities for μ- and δ-receptors are reported. The highest affinity, bioactivity and selectivity are shown by peptides 2 and 3 containing the Aze residue.     

BH(4) (tetrahydrobiopterin)-dependent activation, but not the expression, of inducible NOS (nitric oxide synthase)-2 in proinflammatory cytokine-stimulated, cultured normal human astrocytes is mediated by MEK-ERK kinases

Nitric oxide (NO) from astrocytes is one of the signalers used by the brain's extensive glial-neuronal-vascular network, but its excessive production by pro-inflammatory cytokine-stimulated glial cells can be cytodestructive. Here, we show how three pro-inflammatory cytokines (IL-1beta, TNF-alpha, and IFN-gamma) together stimulated the activation, but not the prior expression, of NOS-2 protein via a mechanism involving MEK-ERKs protein kinases in astrocytes from adult human cerebral temporal cortex. The cytokines triggered a transient burst of p38 MAPK activity and the production of NOS-2 mRNA which were followed by bursts of MEK-ERK activities, synthesis of the NOS-2 co-factor tetrahydrobiopterin (BH(4)), a build-up of NOS-2 protein and from it active NOS-2 enzyme. Selectively inhibiting MEK1/MEK2, but not the earlier burst of p38 MAPK activity, with a brief exposure to U0126 between 24 and 24.5 h after adding the cytokine triad affected neither NOS-2 expression nor NOS-2 protein accumulation but stopped BH(4) synthesis and the assembly of the NOS-2 protein into active NOS-2 enzyme. The complete blockage of active NOS-2 production by the brief exposure to U0126 was bypassed by simply adding BH(4) to the culture medium. Therefore, this cytokine triad triggered two completely separable, tandem operating mechanisms in normal human astrocytes, the first being NOS-2 gene expression and accumulation of NOS-2 protein and the second being the synthesis of the BH(4) factor needed to dimerize the NOS-2 protein into active, NO-making NOS-2 enzyme.     

The "far-west" of Anopheles gambiae molecular forms

The main Afrotropical malaria vector, Anopheles gambiae sensu stricto, is undergoing a process of sympatric ecological diversification leading to at least two incipient species (the M and S molecular forms) showing heterogeneous levels of divergence across the genome. The physically unlinked centromeric regions on all three chromosomes of these closely related taxa contain fixed nucleotide differences which have been found in nearly complete linkage disequilibrium in geographic areas of no or low M-S hybridization. Assays diagnostic for SNP and structural differences between M and S forms in the three centromeric regions were applied in samples from the western extreme of their range of sympatry, the only area where high frequencies of putative M/S hybrids have been reported. The results reveal a level of admixture not observed in the rest of the range. In particular, we found: i) heterozygous genotypes at each marker, although at frequencies lower than expected under panmixia; ii) virtually all possible genotypic combinations between markers on different chromosomes, although genetic association was nevertheless detected; iii) discordant M and S genotypes at two X-linked markers near the centromere, suggestive of introgression and inter-locus recombination. These results could be indicative either of a secondary contact zone between M and S, or of the maintenance of ancestral polymorphisms. This issue and the perspectives opened by these results in the study of the M and S incipient speciation process are discussed.     

LTR retrotransposon dynamics in the evolution of the olive (Olea europaea) genome

Improved knowledge of genome composition, especially of its repetitive component, generates important information for both theoretical and applied research. The olive repetitive component is made up of two main classes of sequences: tandem repeats and retrotransposons (REs). In this study, we provide characterization of a sample of 254 unique full-length long terminal repeat (LTR) REs. In the sample, Ty1-Copia elements were more numerous than Ty3-Gypsy elements. Mapping a large set of Illumina whole-genome shotgun reads onto the identified retroelement set revealed that Gypsy elements are more redundant than Copia elements. The insertion time of intact retroelements was estimated based on sister LTR’s divergence. Although some elements inserted relatively recently, the mean insertion age of the isolated retroelements is around 18 million yrs. Gypsy and Copia retroelements showed different waves of transposition, with Gypsy elements especially active between 10 and 25 million yrs ago and nearly inactive in the last 7 million yrs. The occurrence of numerous solo-LTRs related to isolated full-length retroelements was ascertained for two Gypsy elements and one Copia element. Overall, the results reported in this study show that RE activity (both retrotransposition and DNA loss) has impacted the olive genome structure in more ancient times than in other angiosperms.     

A Re-Emerging Marker for Prognosis in Hepatocellular Carcinoma: The Add-Value of FISHing c-myc Gene for Early Relapse

Hepatocellular carcinoma is one leading cause of cancer-related death and surgical resection is still one of the major curative therapies. Recently, there has been a major effort to find mechanisms involved in carcinogenesis and early relapse. c-myc gene abnormality is found in hepatocarcinogenesis. Our aim was to analyze the role of c-myc as prognostic factor in terms of overall survival and disease-free survival and to investigate if c-myc may be an important target for therapy. We studied sixty-five hepatocellular carcinomas submitted to surgical resection with curative intent. Size, macro-microvascular invasion, necrosis, number of nodules, grading and serum alfa-fetoprotein level were registered for all cases. We evaluated the c-myc aberrations by using break-apart FISH probes. Probes specific for the centromeric part of chromosome 8 and for the locus specific c-myc gene (8q24) were used to assess disomy, gains of chromosomes (polysomy due to polyploidy) and amplification. c-myc gene amplification was scored as 8q24/CEP8 > 2. Statistical analysis for disease-free survival and overall survival were performed. At molecular level, c-myc was amplified in 19% of hepatocellular carcinoma, whereas showed gains in 55% and set wild in 26% of cases. The 1- and 3-year disease-free survival and overall survival for disomic, polysomic and amplified groups were significantly different (p=0.020 and p=.018 respectively). Multivariate analysis verified that the AFP and c-myc status (amplified vs. not amplified) were significant prognostic factors for overall patients survival. c-myc gene amplification is significantly correlated with disease-free survival and overall survival in patients with hepatocellular carcinoma after surgical resection and this model identifies patients with risk of early relapse (≤12 months). We suggest that c-myc assessment may be introduced in the clinical practice for improving prognostication (high and low risk of relapse) routinely and may have be proposed as biomarker of efficacy to anti-c-myc targeted drugs in clinical trials.