Modulation of Alzheimer's amyloid β peptide oligomerization and toxicity by extracellular Hsp70

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to dementia caused by advanced neuronal dysfunction and death. The most significant symptoms of AD are observed at late stages of the disease when interventions are most likely too late to ameliorate the condition. Currently, the predominant theory for AD is the “amyloid hypothesis,” which states that abnormally increased levels of amyloid β (Aβ) peptides result in the production of a variety of aggregates that are neurotoxic. The specific mechanisms for Aβ peptide-induced cytotoxicity have not yet been completely elucidated. However, since the majority of Aβ is released into the extracellular milieu, it is reasonable to assume that toxicity begins outside the cells and makes its way inside where it disrupts the basic cellular process resulting in cell death. There is increasing evidence that hsp, particularly Hsp70, are exported into the extracellular milieu by an active export mechanism independent of cell death. Therefore, both Aβ peptides and Hsp70 may coexist in a common environment during pathological conditions. We observed that Hsp70 affected the Aβ assembling process in vitro preventing oligomer formation. Moreover, the presence of Hsp70 reduced the Aβ peptide-induced toxicity of cultured neurons (N2A cells). These results suggest a potential mechanism for the reduction of the detrimental effects of Aβ peptides in AD.     

Bacterial plant oncogenes: Therol genes' saga

Therol genes are part of the T-DNA which is transferred byAgrobacterium rhizogenes in plant cells, causing neoplastic growth and differentiation. Each of these bacterial oncogenes deeply influences plant development and is finely regulated once transferred into the plant host. Both from the study of the effects and biochemical function of therol genes and from the analysis of their regulation, important insight in plant development can be derived. Some of the most intriguing aspects of past, current and future research on this gene system are highlighted and discussed.     

Osimertinib and anti-HER3 combination therapy engages immune dependent tumor toxicity via STING activation in trans

Over the past decade, immunotherapy delivered novel treatments for many cancer types. However, lung cancer still leads cancer mortality, and non-small-cell lung carcinoma patients with mutant EGFR cannot benefit from checkpoint inhibitors due to toxicity, relying only on palliative chemotherapy and the third-generation tyrosine kinase inhibitor (TKI) osimertinib. This new drug extends lifespan by 9-months vs. second-generation TKIs, but unfortunately, cancers relapse due to resistance mechanisms and the lack of antitumor immune responses. Here we explored the combination of osimertinib with anti-HER3 monoclonal antibodies and observed that the immune system contributed to eliminate tumor cells in mice and co-culture experiments using bone marrow-derived macrophages and human PBMCs. Osimertinib led to apoptosis of tumors but simultaneously, it triggered inositol-requiring-enzyme (IRE1α)-dependent HER3 upregulation, increased macrophage infiltration, and activated cGAS in cancer cells to produce cGAMP (detected by a lentivirally transduced STING activity biosensor), transactivating STING in macrophages. We sought to target osimertinib-induced HER3 upregulation with monoclonal antibodies, which engaged Fc receptor-dependent tumor elimination by macrophages, and STING agonists enhanced macrophage-mediated tumor elimination further. Thus, by engaging a tumor non-autonomous mechanism involving cGAS-STING and innate immunity, the combination of osimertinib and anti-HER3 antibodies could improve the limited therapeutic and stratification options for advanced stage lung cancer patients with mutant EGFR.Subject terms: Non-small-cell lung cancer, Prognostic markers, Experimental models of disease, Preclinical research, Growth factor signalling     

Bacteriophage lambda display of complex cDNA libraries: a new approach to functional genomics

We describe the construction and characterization of two lambda surface displayed cDNA expression libraries derived from human brain and mouse embryo. cDNA inserts were obtained by tagged random-priming elongation of commercially available cDNA libraries and cloned into a novel lambda vector at the 3' end of the D capsid protein gene, which produced highly complex repertoires (1x10(8) and 2x10(7) phage). These libraries were affinity selected with a monoclonal antibody against the neural specific factor GAP-43 and with polyclonal antibodies that recognize the EMX1 and EMX2 homeoproteins. In both cases rapid identification of specific clones was achieved, which demonstrates the great potential of the lambda display system for generating affinity selectable cDNA libraries from complex genomes.     

Sperm-egg interaction at fertilization: glycans as recognition signals

This article first examines the events occurring in male and female genital tracts, which prepare human sperm to encounter the egg. Central is a glycoprotein, gp20, homologous to the leukocyte antigen CD52. This protein is secreted in the epididymal cells, inserted in the sperm plasma membrane and exposed in the equatorial region of the head at the end of the capacitation process. The mechanisms and molecules of the first interaction event between gametes in the mollusk bivalve Unio elongatulus and the current state of our knowledge of the same interaction in other species is then considered. The egg of Unio is very peculiar because it is highly polarized. Similar to other well-known egg models, the ligand for recognition is located on the egg coat which is a sort of fibrous network made up of very few glycoproteins, while the receptor is on the sperm surface. The difference is that in this egg, the ligand molecules are not uniformly distributed but are restricted to an area of the egg coat at the vegetal pole, the crater area. The role of carbohydrates in ligand function and of a specific type of oligosaccharide chain in particular, is discussed in the wider context of glycans acting as recognition signals.     

Effects of four aromatic organic pollutants on microbial glucose metabolism and thymidine incorporation in marine sediments

The metabolism of D-[U-14C]glucose and the incorporation of [methyl-3H]thymidine by aerobic and anaerobic marine sediment microbes exposed to 1 to 1,000 ppm anthracene, naphthalene, p,p'-dichlorodiphenyltrichloroethane, and pentachlorophenol were examined. Cell-specific rates of [14C]glucose metabolism averaged 1.7 X 10(-21) and 0.5 X 10(-21) mol/min per cell for aerobic and anaerobic sediment slurries, respectively; [3H]thymidine incorporation rates averaged 43 X 10(-24) and 9 X 10(-24) mol/min per cell for aerobic and anaerobic slurries, respectively. Aerobic sediments exposed to three of the organic pollutants for 2 to 7 days showed recovery of both activities. Anaerobic sediments showed little recovery after 2 days of pre-exposure to the pollutants. We conclude that (i) anaerobic sediments are more sensitive than aerobic sediments to pollutant additions; (ii) [3H]thymidine incorporation is more sensitive to pollutant additions than is [14C]glucose metabolism; and (iii) the toxicity of the pollutants increased in the following order: anthracene, p,p'-dichlorodiphenyltrichloroethane, naphthalene, and pentachlorophenol.     

Degassing of Pore Water Methane during Sediment Incubations

Laboratory experiments were used to examine the degassing of CH₄ from a muddy sediment. Sediment containing dissolved CH₄ showed a hyperbolic time course of CH₄ release when allowed to degas in stoppered 20-ml vials. Equilibration required ca. 24 h for 5 ml of sediment. The rate of CH₄ release was found to be dependent on the ratio of exposed sediment surface area to sediment volume. The water content of the sediment was a factor in the total amount of CH₄ released but did not affect the rate of degassing. Addition of water to sediment samples (to form a slurry) accelerated CH₄ release, with a 1:1 dilution giving ca. 80% of maximum release after only 2 min. Shaking (vortexing) the sediments also facilitated CH₄ exchange, with 2 min of vigorous agitation giving 77% of maximum release. The organic content of the sediment did not affect either the amount or the rate of CH₄ degassing. Rubber stoppers exposed to CH₄ were found to absorb CH₄ rapidly and to subsequently release it in proportion to the concentration to which they were exposed. Artifacts may be associated with CH₄ production measurements if sediment and stopper degassing are not considered. It is recommended that any study of methane production or distribution include preliminary experiments to determine the degassing kinetics for the specific sediment system being used.     

Thalamo-cortical spiking model of incremental learning combining perception,context and NREM-sleep

The brain exhibits capabilities of fast incremental learning from few noisy examples, as well as the ability to associate similar memories in autonomously-created categories and to combine contextual hints with sensory perceptions. Together with sleep, these mechanisms are thought to be key components of many high-level cognitive functions. Yet, little is known about the underlying processes and the specific roles of different brain states. In this work, we exploited the combination of context and perception in a thalamo-cortical model based on a soft winner-take-all circuit of excitatory and inhibitory spiking neurons. After calibrating this model to express awake and deep-sleep states with features comparable with biological measures, we demonstrate the model capability of fast incremental learning from few examples, its resilience when proposed with noisy perceptions and contextual signals, and an improvement in visual classification after sleep due to induced synaptic homeostasis and association of similar memories.     

On the mechanism of eukaryotic cell penetration by α- and β-oligoarginines--targeting infected erythrocytes

Fluorescein-labeled α- and β-octaarginine amides were synthesized. The route, by which these oligoarginine (OA) derivatives enter cells (hepatocytes, fibroblasts, macrophages), was investigated by confocal fluorescence microscopy. Comparisons (by co-localization experiments) with compounds of known penetration modes revealed that the β-octaarginine amide also uses multiple pathways to enter cells. There was no difference between the α- and the β-OAs. Like other cell-penetrating peptides (CPPs), the β-octaarginine eventually winds up in the nucleoli of the cell nuclei (cf. Chem. Biodiversity, 2004, 1, 65). Surprisingly, there was no entry of α- or β-OA into intact and healthy human erythrocytes (which do not possess a nucleus). Blood cells infected by Plasmodium falciparum (malaria parasite) were, however, entered readily, and the OAs went all the way through a couple of membranes into the parasite. The potential of these results for delivering specific antimalarial drugs directly into the parasite is discussed.     

Anti-metastatic potential of human Vδ1+ γδ T cells in an orthotopic mouse xenograft model of colon carcinoma

The role of human intraepithelial Vδ1⁺ γδ T cell cytotoxic effectors in the immune surveillance against metastatic colon cancer has never been addressed, despite their reported capacity to infiltrate colon carcinomas and to kill colonic cancer cells in vitro. We previously showed that Vδ1⁺ γδ T cells are enriched in blood in response to cytomegalovirus (CMV) infection, and that such increase may be protective against epithelial cancers. The objective of the present study was to investigate whether CMV-induced Vδ1⁺ γδ T lymphocytes could inhibit the propagation of human colon tumors in vivo, in order to evaluate their immunotherapeutic potential in this context. Even though metastases are an important cause of death in various cancers including colorectal cancer (CRC), the anti-metastatic effect of immune effectors has been poorly analyzed. To this purpose, we set up a reliable model of metastatic colon cancer through orthotopic implantation of luciferase-expressing human HT29 cells in immunodeficient mice. Using bioluminescence imaging to follow the outcome of colonic cancer cells, we showed that a systemic treatment with CMV-induced Vδ1⁺ γδ T cells could not only inhibit primary colon tumor growth but also the emergence of secondary tumor foci in the lungs and liver. Finally, our data lead to propose that Vδ1⁺ γδ T lymphocytes may directly influence the appearance of metastases independently from their control of primary tumor size. These findings, which extend our previous work, pave the road for the potential manipulation of Vδ1⁺ γδ T lymphocytes in novel anti-CRC immunotherapeutic protocols.