Regulation of β-catenin stabilization in human platelets

The Wnt/β-catenin pathway controls developmental processes and homeostasis; however, abnormal activation of this pathway has been linked to several human diseases. Recent reports have demonstrated regulation of platelet function by canonical and non-canonical Wnt signalling. Platelet aggregation plays a crucial role in haemostasis and thrombosis. Here we report for the first time that, induction of sustained aggregation of platelets by a strong agonist in the presence of calcium was associated with nearly complete proteolysis of β-catenin, which was abrogated upon depletion of calcium from platelet suspension. β-catenin cleavage was disallowed in absence of aggregation, thus implicating integrin α_IIbβ₃ engagement in β-catenin proteolysis. Degradation of β-catenin was blocked partially by inhibitors of either proteasome or calpain and completely when cells were exposed to both the inhibitors. Protein kinase C inhibition, too, abolished β-catenin degradation. Thus activities of proteasome, calpain and protein kinase C regulate stabilization of β-catenin in aggregated human platelets.     

Aerosol generation using nanometer liposome suspensions for pulmonary drug delivery applications

Abstract

Pulmonary lung targeting finds applications in drug delivery to the lung itself and to other body organs, via blood circulation following transfer across alveolar membranes. Understanding pulmonary drug delivery systems towards improving their efficacy needs identification of particle sizes of relevance and elucidation of links between suspension properties, techniques of atomisation and properties of the generated aerosols. This review article is focussed on understanding the elements of pulmonary drug delivery, specifically related to suspensions of small liposomes. Specific objectives of this review include (a) understanding aerosol particle deposition and absorption on pulmonary surface, (b) links between properties of aerosol generation and colloidal drug carriers used for drug encapsulation, and (c) investigation on the controlled properties of liposome aerosols generated using different atomisation techniques for efficacious aerosol therapy.     

Tryptophan to Glycine mutation in the position 116 leads to protein aggregation and decreases the stability of the LITAF protein

Mutations in the gene-encoding vesicle lipopolysaccharide-induced tumor necrosis factor (LITAF) protein cause Charcot–Marie–Tooth type 1C (CMT1C) disease, a neurological disorder. The LITAF gene is mapped to chromosome number 16 and can be found at cytogenetic location 16p13 of the chromosome. CMT1C-linked small integral membrane protein of lysosome/late endosome mutants are loss-of-function mutants that act in a dominant negative manner to impair endosomal trafficking, leading to prolonged extracellular signal-regulated kinases 1/2 signaling downstream of ErbB activation. Mutation W116G in the LITAF decreases the stability of the protein and also interrupts the functioning of gene. We have analyzed the single nucleotide polymorphism (SNP) results of 28 nsSNPs obtained from dbSNP. We also carried out multiple molecular dynamics simulations of 200 ns and obtained results of root-mean-square deviation, root-mean-square fluctuation, radius of gyration, solvent-accessible surface area, H-bond, and principal component analysis to check and prove the stability of both the wild type and the mutant. The protein was then checked for its aggregation and the results showed loss of helix. The loss of helix leads to the instability of the protein.     

Fibrillation of human serum albumin shows nonspecific coordination on stoichiometric increment of Copper(II)

Protein aggregation is related to a series of pathological disorders the main cause of which are the fibrillar species generated during the process. Human serum albumin (HSA) undergoes rapid fibrillation in the presence of Cu(II) at pH 7.4 in 60% ethanol after 6-h incubation (～65?°C) followed by room temperature incubation. Here, we have investigated the effect of a stoichiometric variation of Cu(II) on the self-assembly of HSA using Congo red and thioflavin T dye-binding studies, circular dichroism spectroscopy, Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, fluorescence microscopy and transmission electron microscopy. The simulation of EPR spectra suggests that with the increment in Cu(II) ion concentration, there is a change in ligand field coordination. Kinetic parameters indicate reduced cooperativity that may be related to the nonspecific coordination on increment of Cu(II) concentration. Cu(II) is also able to direct the accumulation of a large number of fibers along with a formation of dense fibrillar network which is evident from microscopic images.     

Aggregation pheromone in Dermestes maculatus: effects on larval growth and developmental rhythms

Observations on the effect of an aggregation pheromone of Dermestes maculatus indicate the production and liberation with faeces of two different compounds of a primer type. One is produced by larvae themselves and accelerates growth, the other is produced by adults and inhibits larval development. Both larval and adult pheromones synchronize larval ecdyses.     

Expanding the prion concept to cancer biology: dominant-negative effect of aggregates of mutant p53 tumour suppressor

p53 is a key protein that participates in cell-cycle control, and its malfunction can lead to cancer. This tumour suppressor protein has three main domains; the N-terminal transactivation domain, the CTD (C-terminal domain) and the core domain (p53C) that constitutes the sequence-specific DBD (DNA-binding region). Most p53 mutations related to cancer development are found in the DBD. Aggregation of p53 into amyloid oligomers and fibrils has been shown. Moreover, amyloid aggregates of both the mutant and WT (wild-type) forms of p53 were detected in tumour tissues. We propose that if p53 aggregation occurred, it would be a crucial aspect of cancer development, as p53 would lose its WT functions in an aggregated state. Mutant p53 can also exert a dominant-negative regulatory effect on WT p53. Herein, we discuss the dominant-negative effect in light of p53 aggregation and the fact that amyloid-like mutant p53 can convert WT p53 into more aggregated species, leading into gain of function in addition to the loss of tumour suppressor function. In summary, the results obtained in the last decade indicate that cancer may have characteristics in common with amyloidogenic and prion diseases.     

Anti-thrombosis effect of diosgenyl saponins in vitro and in vivo

Thrombosis in coronary or cerebral arteries is the major cause of morbidity and mortality worldwide. Diosgenin and total steroidal saponins extracted from the rhizome of Dioscorea zingiberensis C.H. Wright are demonstrated to have anti-thrombotic activity. However, few studies describe the anti-thrombotic activity of the diosgenyl saponin monomer. In the present study, a simple and convenient method for the preparation of a new disaccharide saponin, diosgenyl β-d-galactopyranosyl-(1 → 4)-β-d-glucopyranoside (3), is described. We evaluated the anti-thrombotic effects of diosgenin and four diosgenyl saponins by measuring the bleeding time; the results showed that compound 3 exhibits outstanding efficiency in prolonging the bleeding time. Furthermore, we assessed whether compound 3 could alter platelet aggregation in vitro and in vivo. In addition, activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT), coagulation factors and protection rate in mice were measured to evaluate the anti-thrombotic effect of compound 3. The results show that compound 3 inhibited platelet aggregation, prolonged APTT, inhibited factor VIII activities in rats, and increased the protection rate in mice in a dose-dependent manner. Taken together, these findings suggested that diosgenyl saponins, especially compound 3, had anti-thrombotic activity. It may execute anti-thrombotic activity through inhibiting factor VIII activities and platelet aggregation.     

Horizontal transmission of the microbial symbionts Enterobacter cloacae and Mycotypha microspora to their firebrat host

The firebrat, Thermobia domestica (Packard) (Thysanura: Lepismatidae), aggregates in response to the faeces of conspecifics. This aggregation response is mediated by two microbial symbionts, the bacterium Enterobacter cloacae (Jordan) Hormaeche & Edwards (Enterobacteriaceae) and the fungus Mycotypha microspora Fenner (Mucorales). Our objective was to determine how these microbes are transmitted between firebrats. We produced fluorescently labelled E. cloacae and M. microspora and presented them to firebrats. Firebrats consumed large quantities of these labelled microbes and deposited them with their faeces where they proliferated rapidly. Firebrats did not harbour E. cloacae or M. microspora within their ovarioles or eggs, and thus cannot transmit them transovarially. Instead, firebrats acquired them horizontally whenever they fed on microbe‐contaminated material, such as faeces, faeces‐contaminated paper, or egg surfaces. Firebrats moult throughout their life, and with each moult they shed the cuticular lining of their digestive tract and likely any microbes residing therein. Because firebrats remain in close contact and live in groups of mixed age and gender, newly moulted individuals can readily re‐acquire E. cloacae or M. microspora from group members. This ensures the perpetuation of their microbial aggregation and arrestment signal.     

Integration of New Genes into Cellular Networks,and Their Structural Maturation

It has been recently discovered that new genes can originate de novo from noncoding DNA, and several biological traits including expression or sequence composition form a continuum from noncoding sequences to conserved genes. In this article, using yeast genes I test whether the integration of new genes into cellular networks and their structural maturation shows such a continuum by analyzing their changes with gene age. I show that 1) The number of regulatory, protein–protein, and genetic interactions increases continuously with gene age, although with very different rates. New regulatory interactions emerge rapidly within a few million years, while the number of protein–protein and genetic interactions increases slowly, with a rate of 2–2.25 × 10⁻⁸/year and 4.8 × 10⁻⁸/year, respectively. 2) Gene essentiality evolves relatively quickly: the youngest essential genes appear in proto-genes ∼14 MY old. 3) In contrast to interactions, the secondary structure of proteins and their robustness to mutations indicate that new genes face a bottleneck in their evolution: proto-genes are characterized by high β-strand content, high aggregation propensity, and low robustness against mutations, while conserved genes are characterized by lower strand content and higher stability, most likely due to the higher probability of gene loss among young genes and accumulation of neutral mutations.     

Quinones bearing non-steroidal anti-inflammatory fragments as multitarget ligands for Alzheimer’s disease

The anti-amyloid properties shared by several quinones inspired the design of a new series of hybrids derived from the multi-target drug candidate memoquin (1). The hybrids consist of a central benzoquinone core and a fragment taken from non-steroidal anti-inflammatory drugs, connected through polyamine linkers. The new hybrids retain the potent anti-aggregating activity of the parent 1, while exhibiting micromolar AChE inhibitory activities. Remarkably, 2, 4, (R)-6 and (S)-6 were Aβ aggregation inhibitors even more potent than 1. The balanced amyloid/cholinesterase inhibitory profile is an added value that makes the present series of compounds promising leads against Alzheimer’s disease.