Short stretches of rare codons regulate translation of the transcription factor ZEB2 in cancer cells.

Two proteins comprising the ZEB family of zinc finger transcription factors, ZEB1 and ZEB2, execute EMT programs in embryonic development and cancer. By studying regulation of their expression, we describe a novel mechanism that limits ZEB2 protein synthesis. A protein motif located at the border of the SMAD-binding domain of ZEB2 protein induces ribosomal pausing and compromises protein synthesis. The function of this protein motif is dependent on stretches of rare codons, Leu(UUA)-Gly(GGU)-Val(GUA). Incorporation of these triplets in the homologous region of ZEB1 does not affect protein translation. Our data suggest that rare codons have a regulatory role only if they are present within appropriate protein structures. We speculate that pools of transfer RNA available for protein translation impact on the configuration of epithelial mesenchymal transition pathways in tumor cells.

[Characterization of the extracellular proteasomes and its interacting proteins by iTRAQ mass spectrometry].

The analysis of the extracellular proteasomes by isobaric tagging for relative and absolute quantifications (iTRAQ) mass spectrometry has been carried out. Here we show a standard set of 26S proteasomal subunits in the composition of the extracellular proteasomes. Moreover, extracellular proteasomes have a number of PA200 activators, which, as previously thought, are localized in the cell nucleus. Posttranslational modifications (PTMs) of subunits of the extracellular proteasomes were revealed by iTRAQ mass spectrometry. For the first time we have identified several ubiquitination and acetylation sites on subunits alpha2 (K196), alpha4 (K189 and K234), alpha6 (K217), and Rpn6 (A2). We have revealed a large number of proteasome-interacting proteins that are involved in various cell processes, such as transcription, DNA repair, translation, cytoskeletal proteins and the proteins of the ubiquitin-proteasome system (UPS). Immunoblot analysis has confirmed the interactions between purified extracellular proteasomes and nine proteins which were randomly selected from the set of interacting proteins.

Determination of end groups of synthetic polymers by matrix-assisted laser desorption/ionization: high-energy collision-induced dissociation.

Matrix-assisted laser desorption/ionization has been combined with high-energy collision-induced dissociation for the analysis of poly(ethylene glycols) with butanoyl, benzoyl and acetyl end groups, using novel technology comprising a magnetic-sector mass spectrometer and ion buncher with an in-line quadratic-field ion mirror. High-energy (>8 keV) collision-induced dissociation facilitated unambiguous end-group determination of these polymers, providing masses of end groups and structural information. The high-energy collision-induced dissociation also provided information regarding repeat units.

Attitudes to patients who attempt suicide.

A survey of attitudes towards persons who attempt suicide is described. A considerable degree of non-sympathy was reported, particularly by those hospital-based staff members who have initial contact with these patients, not only for personal attitude, but also for professional attitude. Although behaviour in the clinical situation cannot necessarily be assumed on the basis of expressed attitudes, these results give grounds for concern, as there are suggestions in the literature that further suicidal behaviour may be precipitated in such patients if they perceive rejection by therapists.