Stabilization of the activated alphaMbeta2 integrin by a small molecule inhibits leukocyte migration and recruitment

Integrins are potential targets for the development of antiinflammatory agents. Here we develop a novel high-throughput assay by allowing a chemical library to compete with phage display peptide binding and identify a novel small-molecule ligand to the leukocyte-specific alpha(M)beta(2) integrin. The identified thioxothiazolidine-containing compound, IMB-10, had an unexpected activity in that it stabilized binding of alpha(M)beta(2) to its endogenous ligands proMMP-9 and fibrinogen. Single amino acid substitutions in the activity-regulating C-terminal helix and the underlying region in the ligand-binding I domain of the integrin suppressed the effect of IMB-10. A computational model indicated that IMB-10 occupies a distinct cavity present only in the activated form of the integrin I domain. IMB-10 inhibited alpha(M)beta(2)-dependent migration in vitro and inflammation-induced neutrophil emigration in vivo. Stabilization of integrin-mediated adhesion by a small molecule is a novel means to inhibit cell migration and may have a utility in treatment of inflammatory diseases involving leukocyte recruitment.     

Arresten,a Collagen-Derived Angiogenesis Inhibitor,Suppresses Invasion of Squamous Cell Carcinoma

The turnover of extracellular matrix liberates various cryptic molecules with novel biological activity. Among these are the collagen-derived anti-angiogenic fragments, some of which are suggested to affect carcinoma cells also directly. Arresten is an endogenous angiogenesis inhibitor that is derived from the non-collagenous domain of the basement membrane collagen IV α1 chain. As the mere prevention of tumor angiogenesis leads to hypoxia that can result in selection of more aggressive cell types and reduces the efficacy of chemotherapy, we aimed here to elucidate how arresten influences the aggressive human carcinoma cells. Arresten efficiently inhibited migration and invasion of HSC-3 tongue carcinoma cells in culture and in an organotypic model. Subcutaneous Arr-HSC xenografts grew markedly more slowly in nude mice and showed reduced tumor cell proliferation, vessel density and local invasiveness. In the organotypic assay, HSC-3 cells overproducing arresten (Arr-HSC) showed induction of cell death. In monolayer culture the Arr-HSC cells grew in aggregated cobblestone-like clusters and, relative to the control cells, showed increased expression and localization of epithelial marker E-cadherin in cell-cell contacts. Application of electric cell-substrate impedance sensing (ECIS) further supported our observations on altered morphology and motility of the Arr-HSC cells. Administration of a function-blocking α1 integrin antibody abolished the impedance difference between the Arr-HSC and control cells suggesting that the effect of arresten on promotion of HSC-3 cell-cell contacts and cell spreading is at least partly mediated by α1β1 integrin. Collectively, our data suggest novel roles for arresten in the regulation of oral squamous carcinoma cell proliferation, survival, motility and invasion through the modulation of cell differentiation state and integrin signaling.     

Multiple endosymbionts in populations of the ant <Emphasis Type="Italic">Formica cinerea</Emphasis>

Background  

Many insects, including ants, are infected by maternally inherited Wolbachia endosymbiotic bacteria though other secondary endosymbionts have not been reported in ants. It has been suggested that the ability of Wolbachia to invade and remain in an ant population depends on the number of coexisting queens in a colony. We study the genetic and social structure of populations in the ant Formica cinerea which is known to have populations with either monogynous or polygynous colonies. We screen populations for several endosymbiotic bacteria to evaluate the presence of different endosymbionts, possible association between their prevalence and the social structure, and the association between endosymbiont prevalence and genetic differentiation of ant populations.     

LOCAL ADAPTATION IN A CHANGING WORLD: THE ROLES OF GENE‐FLOW,MUTATION, AND SEXUAL REPRODUCTION

In spatially heterogeneous environments, the processes of gene flow, mutation, and sexual reproduction generate local genetic variation and thus provide material for local adaptation. On the other hand, these processes interchange maladapted for adapted genes and so, in each case, the net influence may be to reduce local adaptation. Previous work has indicated that this is the case in stable populations, yet it is less clear how the factors play out during population growth, and in the face of temporal environmental stochasticity. We address this issue with a spatially explicit, stochastic model. We find that dispersal, mutation, and sexual reproduction can all accelerate local adaptation in growing populations, although their respective roles may depend on the genetic make‐up of the founding population. All three processes reduce local adaptation, however, in the long term, that is when population growth becomes balanced by density‐dependent competition. These relationships are qualitatively maintained, although quantitatively reduced, if the resources are locally ephemeral. Our results suggest that species with high levels of local adaptation within their ranges may not be the same species that harbor potential for rapid local adaptation during population expansion.     

No effects of short-term GSM mobile phone radiation on cerebral blood flow measured using positron emission tomography

The present study investigated the effects of 902.4 MHz Global System for Mobile Communications (GSM) mobile phone radiation on cerebral blood flow using positron emission tomography (PET) with the ¹⁵O‐water tracer. Fifteen young, healthy, right‐handed male subjects were exposed to phone radiation from three different locations (left ear, right ear, forehead) and to sham exposure to test for possible exposure effects on brain regions close to the exposure source. Whole‐brain [¹⁵O]H₂O–PET images were acquired 12 times, 3 for each condition, in a counterbalanced order. Subjects were exposed for 5 min in each scan while performing a simple visual vigilance task. Temperature was also measured in the head region (forehead, eyes, cheeks, ear canals) during exposure. The exposure induced a slight temperature rise in the ear canals but did not affect brain hemodynamics and task performance. The results provided no evidence for acute effects of short‐term mobile phone radiation on cerebral blood flow. Bioelectromagnetics 33:247–256, 2012. © 2011 Wiley Periodicals, Inc.     

Biomarker Discovery by Sparse Canonical Correlation Analysis of Complex Clinical Phenotypes of Tuberculosis and Malaria

Biomarker discovery aims to find small subsets of relevant variables in ‘omics data that correlate with the clinical syndromes of interest. Despite the fact that clinical phenotypes are usually characterized by a complex set of clinical parameters, current computational approaches assume univariate targets, e.g. diagnostic classes, against which associations are sought for. We propose an approach based on asymmetrical sparse canonical correlation analysis (SCCA) that finds multivariate correlations between the ‘omics measurements and the complex clinical phenotypes. We correlated plasma proteomics data to multivariate overlapping complex clinical phenotypes from tuberculosis and malaria datasets. We discovered relevant ‘omic biomarkers that have a high correlation to profiles of clinical measurements and are remarkably sparse, containing 1.5–3% of all ‘omic variables. We show that using clinical view projections we obtain remarkable improvements in diagnostic class prediction, up to 11% in tuberculosis and up to 5% in malaria. Our approach finds proteomic-biomarkers that correlate with complex combinations of clinical-biomarkers. Using the clinical-biomarkers improves the accuracy of diagnostic class prediction while not requiring the measurement plasma proteomic profiles of each subject. Our approach makes it feasible to use omics'' data to build accurate diagnostic algorithms that can be deployed to community health centres lacking the expensive ‘omics measurement capabilities.     

Tissue distribution and half-life of 125I-endothelin in the rat: importance of pulmonary clearance

Plasma half-life and organ uptake of endothelin 1 (ET-1) was studied in anaesthetized Wistar rats administering a bolus of 125I-labeled ET-1 into jugular vein, with and without a preceding dose of 1-80 ng of unlabeled ET-1, via the same route. Plasma half-life of intact 125I-ET-1 was 40 sec and that of total radioactivity 68 sec. Immunoreactivity of circulating 125I-ET was rapidly reduced, by 23% at 30 sec and by 43% at 360 sec, respectively. High power liquid chromatography of plasma extracts revealed a corresponding decrease of intact 125I-ET-1 peak with time. There was a predominant uptake of 125I-ET-1 in the lungs, 82%, and lesser by kidneys, 10%, heart 3.6%, liver, 2.7%, and spleen, 1.5%, respectively. Pretreatment with unlabeled ET-1 caused a dose-dependent shift of uptake from lungs to kidneys. We conclude that circulating ET-1 is rapidly cleared, primarily by the lungs, which may play an important role in protecting the systemic circulation from the vasoconstricting actions of ET-1.     

Investigation of the effect of erythrosine B on amyloid beta peptide using molecular modeling

Neurotoxic plaques composed of 39 to 42 residue-long amyloid beta peptides (Aβs) are copiously present in the brains of patients with Alzheimer’s disease (AD). Erythrosine B (ER), a xanthene food dye, inhibits the formation of Aβ fibrils and Aβ-associated cytotoxicity in vitro. Here, in an attempt to elucidate the inhibition mechanism, we performed molecular dynamics (MD) simulations to demonstrate the conformational change of Aβ40 induced by ER molecules in atomistic detail. During the simulation, the ER bound to the surfaces of both N-terminus and C-terminus regions of Aβ40. Our result shows that ER interacts with the aromatic side chains at the N-terminus region resulting in destabilization of the inter-chain stacking of Aβ40. Moreover, the stablility of the helical structures at the residues from 13 to 16 suggests that ER disturbs conformational transition of Aβ40. At the C-terminus region, the bound ER blocks water molecules and stabilizes the α-helical structure. Regardless of the number of ER molecules used, the interruption of the formation of the salt-bridge between aspartic acid 23 and lysine 28 occurred. To further validate our analysis, binding free energies of ER at each binding site were evaluated. The finding of stronger binding energy at the N-terminus region supports an inhibition mechanism induced by stacking interaction between ER and phenylalanine. These findings could aid present and future treatment studies for AD by clarifying the inhibition mechanism of ER on the conformational transition of Aβ40 at the molecular level.

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Graphical Abstract Conformation of two ER molecules binding to the surface of Aβ40 peptide. The ERs and Aβ40 are represented by black and cyan color, respectively