A Nuclear Stress Pathway that Parallels Cytoplasmic Stress Granule Formation.

Stress adaptation is exploited by cancer cells to survive and proliferate under adverse conditions. Survival pathways induced by stress are thus highly promising therapeutic targets. One key pathway involves formation of cytoplasmic stress granules, which regulate the location, stability, and translation of specific mRNAs. Here, we describe a transcriptional stress response that is triggered by similar stressors and characterized by accumulation of RepoMan (cell division cycle associated 2) at nuclear stress foci (nucSF). Formation of these structures is reversible, and they are distinct from known nuclear organelles and stress bodies. Immunofluorescence analysis revealed accumulation of heterochromatic markers, and increased association of RepoMan with the adenylate cyclase 2 (ADCY2) gene locus in stressed cells accompanied reduced levels of ADCY2 mRNA and protein. Quantitative comparison of the RepoMan interactome in stressed vs. unstressed cells identified condensin II as a nucSF factor, suggesting their functional association in the establishment and/or maintenance of these facultative heterochromatic domains.

Proteome and phosphoproteome of Africanized and European honeybee venoms.

Honey bee venom toxins trigger immunological, physiological, and neurological responses within victims. The high occurrence of bee attacks involving potentially fatal toxic and allergic reactions in humans and the prospect of developing novel pharmaceuticals make honey bee venom an attractive target for proteomic studies. Using label-free quantification, we compared the proteome and phosphoproteome of the venom of Africanized honeybees with that of two European subspecies, namely Apis mellifera ligustica and A. m. carnica. From the total of 51 proteins, 42 were common to all three subspecies. Remarkably, the toxins melittin and icarapin were phosphorylated. In all venoms, icarapin was phosphorylated at the (205) Ser residue, which is located in close proximity to its known antigenic site. Melittin, the major toxin of honeybee venoms, was phosphorylated in all venoms at the (10) Thr and (18) Ser residues. (18) Ser phosphorylated melittin-the major of its two phosphorylated forms-was less toxic compared to the native peptide.

Novel allergens from ancient foods: Man e 5 from manioc (Manihot esculenta Crantz) cross reacts with Hev b 5 from latex.

SCOPE: Manioc (Manihot esculenta) is a tuber mainly consumed in the Southern Hemisphere and used worldwide by food and chemistry industry. We aimed to recombinantly produce and characterize the first manioc allergen and evaluate its IgE reactivity in sera of Brazilian and Italian patients. METHODS AND RESULTS: The molecule, termed Man e5, was expressed in E. coli, characterized by amino acid analysis, mass spectrometry, circular dichroism, HPLC, and dynamic light scattering. A tertiary structural model of the protein was produced using bioinformatics and susceptibility to pepsin digestion was analyzed in vitro. Based on its high content of charged residues, heat stability, flexibility and lack of secondary structure elements, the allergen was determined a member of the intrinsically disordered protein family. Brazilian patients were selected based on manioc allergy and Italians based on latex allergy and sensitization to Hev b 5.71% of Brazilians and 40% of Italians were in vitro IgE positive to Man e5. Cross-inhibition assays suggest a possible involvement of this allergen in the latex-fruit syndrome. CONCLUSION: Man e5, the first purified allergen from manioc demonstrates IgE cross-reactivity with Hev b 5. Data suggest Hev b 5 might act as primary sensitizer and could therefore lead to allergic manifestations upon manioc consumption without prior exposition.

Characterization of two novel polyfunctional mastoparan peptides from the venom of the social wasp Polybia paulista.

Hymenoptera venoms are complex mixtures of biochemically and pharmacologically active components such as biogenic amines, peptides and proteins. Polycationic peptides generally constitute the largest group of Hymenoptera venom toxins, and the mastoparans constitute the most abundant and important class of peptides in the venom of social wasps. These toxins are responsible for histamine release from mast cells, serotonin from platelets, and catecholamines and adenylic acids from adrenal chromafin cells. The present work reports the structural and functional characterization of two novel mastoparan peptides identified from the venom of the neotropical social wasp Polybia paulista. The mastoparans Polybia-MP-II and -III were purified, sequenced and synthesized on solid phase using Fmoc chemistry and the synthetic peptides used for structural and functional characterizations. Polybia-MP-II and -III are tetradecapeptides, amidated at their C-termini, and form amphipathic alpha-helical conformations under membrane-mimetic conditions. Both peptides were polyfunctional, causing pronounced cell lysis of rat mast cells and erythrocytes, in addition to having antimicrobial activity against both Gram-positive and Gram-negative bacteria.