Interferon-alpha induces sensitization of cells to inhibition of protein synthesis by tumour necrosis factor-related apoptosis-inducing ligand

Tumour cells are often sensitized by interferons to the effects of tumour necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL). We have demonstrated previously that TRAIL has an inhibitory effect on protein synthesis [Jeffrey IW, Bushell M, Tilleray VJ, Morley S & Clemens MJ (2002) Cancer Res62, 2272-2280] and we have therefore examined the consequences of prior interferon-alpha treatment for the sensitivity of translation to inhibition by TRAIL. Interferon treatment alone has only a minor effect on protein synthesis but it sensitizes both MCF-7 cells and HeLa cells to the downregulation of translation by TRAIL. The inhibition of translation is characterized by increased phosphorylation of the alpha subunit of eukaryotic initiation factor eIF2 and dephosphorylation of the eIF4E-binding protein 4E-BP1. Both of these effects, as well as the decrease in overall protein synthesis, require caspase-8 activity, although they precede overt apoptosis by several hours. Interferon-alpha enhances the level and/or the extent of activation of caspase-8 by TRAIL, thus providing a likely explanation for the sensitization of cells to the inhibition of translation.     

Stress-induced localization of HSPA6 (HSP70B′) and HSPA1A (HSP70-1) proteins to centrioles in human neuronal cells

The localization of yellow fluorescent protein (YFP)-tagged HSP70 proteins was employed to identify stress-sensitive sites in human neurons following temperature elevation. Stable lines of human SH-SY5Y neuronal cells were established that expressed YFP-tagged protein products of the human inducible HSP70 genes HSPA6 (HSP70B′) and HSPA1A (HSP70-1). Following a brief period of thermal stress, YFP-tagged HSPA6 and HSPA1A rapidly appeared at centrioles in the cytoplasm of human neuronal cells, with HSPA6 demonstrating a more prolonged signal compared to HSPA1A. Each centriole is composed of a distal end and a proximal end, the latter linking the centriole doublet. The YFP-tagged HSP70 proteins targeted the proximal end of centrioles (identified by γ-tubulin marker) rather than the distal end (centrin marker). Centrioles play key roles in cellular polarity and migration during neuronal differentiation. The proximal end of the centriole, which is involved in centriole stabilization, may be stress-sensitive in post-mitotic, differentiating human neurons.     

Functional implications of squamosal suture size in paranthropus boisei

It has been hypothesized that the extensively overlapping temporal and parietal bones of the squamosal sutures in Paranthropus boisei are adaptations for withstanding loads associated with feeding. Finite element analysis (FEA) was used to investigate the biomechanical effects of suture size (i.e., the area of overlap between the temporal and parietal bones) on stress, strain energy, and strain ratio in the squamosal sutures of Pan troglodytes and P. boisei (specimen OH 5) during biting. Finite element models (FEMs) of OH 5 and a P. troglodytes cranium were constructed from CT scans. These models contain sutures that approximate the actual suture sizes preserved in both crania. The FEM of Pan was then modified to create two additional FEMs with squamosal sutures that are 50% smaller and 25% larger than those in the original model. Comparisons among the models test the effect of suture size on the structural integrity of the squamosal suture as the temporal squama and parietal bone move relative to each other during simulated premolar biting. Results indicate that with increasing suture size there is a decreased risk of suture failure, and that maximum stress values in the OH 5 suture were favorable compared to values in the Pan model with the normal suture size. Strain ratios suggest that shear is an important strain regime in the squamosal suture. This study is consistent with the hypothesis that larger sutures help reduce the likelihood of suture failure under high biting loads. Am J Phys Anthropol 153:260–268, 2014. © 2013 Wiley Periodicals, Inc.     

Sequential Depletion and Acquisition of Proteins during Golgi Stack Disassembly and Reformation

Herein, we report the stepwise transport of multiple plant Golgi membrane markers during disassembly of the Golgi apparatus in tobacco leaf epidermal cells in response to the induced expression of the GTP‐locked Sar1p or Brefeldin A (BFA), and reassembly on BFA washout. The distribution of fluorescent Golgi‐resident N‐glycan processing enzymes and matrix proteins (golgins) with specific cis–trans‐Golgi sub‐locations was followed by confocal microscopy during disassembly and reassembly. The first event during Golgi disassembly was the loss of trans‐Golgi enzymes and golgins from Golgi membranes, followed by a sequential redistribution of medial and cis‐Golgi enzymes into the endoplasmic reticulum (ER), whilst golgins were relocated to the ER or cytoplasm. This event was confirmed by fractionation and immuno‐blotting. The sequential redistribution of Golgi components in a trans–cis sequence may highlight a novel retrograde trafficking pathway between the trans‐Golgi and the ER in plants. Release of Golgi markers from the ER upon BFA washout occurred in the opposite sequence, with cis‐matrix proteins labelling Golgi‐like structures before cis/medial enzymes. Trans‐enzyme location was preceded by trans‐matrix proteins being recruited back to Golgi membranes. Our results show that Golgi disassembly and reassembly occur in a highly ordered fashion in plants.     

Emerging aspects of oesophageal and gastro-oesophageal junction cancer histopathology - an update for the surgical oncologist

Adenocarcinoma of the oesophagus and gastro-oesophageal junction are rapidly increasing in incidence and have a well described sequence of carcinogenesis: the Barrett's metaplasia-dysplasia-adenocarcinoma sequence. During recent years there have been changes in the knowledge surrounding disease progression, cancer management and histopathology specimen reporting. Tumours around the gastro-oesophageal junction (GOJ) pose several specific challenges. Numerous difficulties arise when the existing TNM staging systems for gastric and oesophageal cancers are applied to GOJ tumours. The issues facing the current TNM staging and GOJ tumour classification systems are reviewed in this article. Recent evidence regarding the importance of several histopathologically derived prognostic factors, such as circumferential resection margin status and lymph node metastases, have implications for specimen reporting. With the rising use of multimodal treatments for oesophageal cancer it is important that the response of the tumour to this therapy is carefully documented pathologically. In addition, several controversial and novel areas such as endoscopic mucosal resection, lymph node micrometastases and the sentinel node concept are being studied. We aim to review these aspects, with special relevance to oesophageal and gastro-oesophageal cancer specimen reporting, to update the surgical oncologist with an interest in upper gastrointestinal cancer.     

Contact sensitization: A new approach to risk assessment

The murine local lymph node assay is a novel predictive test for the identification of skin sensitizing chemicals. The method measures sensitization potential of a chemical in mice as a function of proliferative activity induced in lymph nodes draining the site of topical exposure to that test chemical. Here we describe the use of the local lymph node assay for evaluation of the relative potency of skin sensitizing chemicals via derivation of the concentration required to produce a threshold positive reaction. Subsequently, the development of risk assessments based on comparisons with index contact allergens is outlined.     

PKC - A pivotal regulator of early development

Oocytes, eggs and blastomeres of the embryo are special cells that undergo rapid changes in structure and function at developmental transitions. These changes are frequently regulated by cytoplasmic signaling events, particularly at the developmental transition of fertilization, because the genome is largely inactivated at this time. Protein kinase C (PKC) is a signaling agent that acts after the sperm-induced rise in calcium and has a central role in the remodeling of the structure of the egg into the zygote in many species. PKC also acts during other developmental transitions. This kinase serves as a chronometer, which can choreograph the cell's remodeling events in both space and time. Several technical advancements discussed in this review have permitted a better understanding of the actions of PKC.     

Ribosomal association of the yeast SAL4 (SUP45) gene product: implications for its role in translation fidelity and termination

The SAL4 gene of the yeast Saccharomyces cerevisiae encodes a novel translation factor (Sal4p) involved in maintaining translational fidelity. Using a polyclonal antibody raised against a Sal4p-beta-galactosidase fusion protein, Sal4p was shown to be almost exclusively associated with the ribosomal fraction. Even when the ribosomes were treated with 0.8 M KCl, only low levels of Sal4p were detected in the post-ribosomal supernatant, suggesting a very strong affinity between Sal4p and the ribosome. Analysis of the distribution of Sal4p in the ribosomal population revealed that it was principally associated with 40S subunits, monosomes and polysomes. Incubation in high salt concentrations (0.8 M KCl) suggested that the affinity of Sal4p for the 40S subunit was lower than that for monosomes or polysomes. The Sal4p:ribosome association was only maintained when ribosomes were prepared in the presence of the translation elongation inhibitor cycloheximide; in uninhibited cells much lower levels of Sal4p were detectable in the 'run-off' polysomes. In view of these data, and given the stoichiometry of Sal4p to individual ribosomal proteins (estimated at less than 1:20), we suggest that Sal4p plays an ancillary role in translation termination.