The membranotropic activity of N-terminal peptides from the pore-forming proteins sticholysin I and II is modulated by hydrophobic and electrostatic interactions as well as lipid composition

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transcription of the Hsp30, Hsp70, and Hsp90 heat shock protein genes is modulated by the PalA protein in response to acid pH-sensing in the fungus Aspergillus nidulans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An interaction between two RNA binding proteins, Nab2 and Pub1, links mRNA Processing/Export and mRNA stability

mRNA stability is modulated by elements in the mRNA transcript and their cognate RNA binding proteins. Poly(U) binding protein 1 (Pub1) is a cytoplasmic Saccharomyces cerevisiae mRNA binding protein that stabilizes transcripts containing AU-rich elements (AREs) or stabilizer elements (STEs). In a yeast two-hybrid screen, we identified nuclear poly(A) binding protein 2 (Nab2) as being a Pub1-interacting protein. Nab2 is an essential nucleocytoplasmic shuttling mRNA binding protein that regulates poly(A) tail length and mRNA export. The interaction between Pub1 and Nab2 was confirmed by copurification and in vitro binding assays. The interaction is mediated by the Nab2 zinc finger domain. Analysis of the functional link between these proteins reveals that Nab2, like Pub1, can modulate the stability of specific mRNA transcripts. The half-life of the RPS16B transcript, an ARE-like sequence-containing Pub1 target, is decreased in both nab2-1 and nab2-67 mutants. In contrast, GCN4, an STE-containing Pub1 target, is not affected. Similar results were obtained for other ARE- and STE-containing Pub1 target transcripts. Further analysis reveals that the ARE-like sequence is necessary for Nab2-mediated transcript stabilization. These results suggest that Nab2 functions together with Pub1 to modulate mRNA stability and strengthen a model where nuclear events are coupled to the control of mRNA turnover in the cytoplasm.

Macrophages and mast cells control the neutrophil migration induced by dentin proteins

Dentin sialoprotein (DSP) and dentin phosphoprotein (DPP), the major dentin proteins, have been shown to induce neutrophil migration through release of IL-1beta, TNF-alpha, MIP-2, and KC. However, the sources of these mediators were not determined. Here, the roles of macrophages and mast cells (MC) in dentin-induced neutrophil accumulation were investigated. Peritoneal MC depletion or the enhancement of macrophage population increased DSP- and DPP-induced neutrophil extravasation. Moreover, supernatants from DSP- and DPP-stimulated macrophages caused neutrophil migration. The release of neutrophil chemotactic factor by macrophages was inhibited by dexamethasone or the supernatant of DSP- treated MC. Consistently, dexamethasone and the MC supernatant inhibited the production of IL-1beta, TNF-alpha, and MIP-2 by macrophages. This inhibitory activity of the DSP- stimulated MC was neutralized by anti-IL-4 and anti-IL-10 antibodies. These results indicate that dentin induces the release of the neutrophil chemotactic substance(s) by macrophages, which are down-modulated by MC-derived IL-4 and IL-10.

The receptor-like kinase SlSOBIR1 is differentially modulated by virus infection but its overexpression in tobacco has no significant impact on virus accumulation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)