Antiprotozoan lead discovery by aligning dry and wet screening: prediction, synthesis, and biological assay of novel quinoxalinones.

Protozoan parasites have been one of the most significant public health problems for centuries and several human infections caused by them have massive global impact. Most of the current drugs used to treat these illnesses have been used for decades and have many limitations such as the emergence of drug resistance, severe side-effects, low-to-medium drug efficacy, administration routes, cost, etc. These drugs have been largely neglected as models for drug development because they are majorly used in countries with limited resources and as a consequence with scarce marketing possibilities.

Haemostatic role of intermediate filaments in adhered platelets: importance of the membranous system stability.

The role of platelets in coagulation and the haemostatic process was initially suggested two centuries ago, and under appropriate physiological stimuli, these undergo abrupt morphological changes, attaching and spreading on damaged endothelium, preventing bleeding. During the adhesion process, platelet cytoskeleton reorganizes generating compartments in which actin filaments, microtubules, and associated proteins are arranged in characteristic patterns mediating crucial events, such as centralization of their organelles, secretion of granule contents, aggregation with one another to form a haemostatic plug, and retraction of these aggregates. However, the role of Intermediate filaments during the platelet adhesion process has not been explored.

A role for β-dystroglycan in the organization and structure of the nucleus in myoblasts.

We recently characterized a nuclear import pathway for β-dystroglycan; however, its nuclear role remains unknown. In this study, we demonstrate for the first time, the interaction of β-dystroglycan with distinct proteins from different nuclear compartments, including the nuclear envelope (NE) (emerin and lamins A/C and B1), splicing speckles (SC35), Cajal bodies (p80-coilin), and nucleoli (Nopp140). Electron microscopy analysis revealed that β-dystroglycan localized in the inner nuclear membrane, nucleoplasm, and nucleoli.

Actin filaments and microtubule dual-granule transport in human adhered platelets: the role of alpha-dystrobrevins.

Upon activation with physiological stimuli, human platelets undergo morphological changes, centralizing their organelles and secreting effector molecules at the site of vascular injury. Previous studies have indicated that the actin filaments and microtubules of suspension-activated platelets play a critical role in granule movement and exocytosis; however, the participation of these cytoskeleton elements in adhered platelets remains unexplored. alpha- and beta-dystrobrevin members of the dystrophin-associated protein complex in muscle and non-muscle cells have been described as motor protein receptors that might participate in the transport of cellular components in neurons.

Physical, structural, and functional properties of the beta1 integrin-like fibronectin receptor (beta1EhFNR) in Entamoeba histolytica.

The presence in Entamoeba histolytica of a fibronectin (FN) receptor, which is antigenically related to beta1 integrin-like molecules and shows 99% homology with the intermediate subunit-2 of the Gal/GalNAc-specific lectin has been described. The E. histolytica genome has been sequenced, and its analysis shows no integrin sequences.

Neuronal differentiation modulates the dystrophin Dp71d binding to the nuclear matrix.

The function of dystrophin Dp71 in neuronal cells remains unknown. To approach this issue, we have selected the PC12 neuronal cell line. These cells express both a Dp71f cytoplasmic variant and a Dp71d nuclear isoform.

Subcellular localization and dynamics of a digalactolipid-like epitope in Toxoplasma gondii.

Toxoplasma gondii is a unicellular parasite characterized by unique extracellular and intracellular membrane compartments. The lipid composition of subcellular membranes has not been determined, limiting our understanding of lipid homeostasis, control, and trafficking, a series of processes involved in pathogenesis. In addition to a mitochondrion, Toxoplasma contains a plastid called the apicoplast.

Utrophins compensate for Dp71 absence in mdx3cv in adhered platelets.

Platelet adhesion is a critical step due to its hemostatic role in stopping bleeding after vascular damage. Short dystrophins are the most abundant dmd gene products in nonmuscle tissues, and in association with cytoskeleton proteins contribute to their intrinsic function; while utrophins are dystrophin-homologous related family proteins with structural and functional similarities. We previously demonstrated the presence of Dp71 isoforms, utrophins, and various dystrophin-associated proteins and their participation in cytoskeleton re-organization, filopodia and lamellipodia extension, and in centralizing cytoplasmic granules during the adhesion process of human platelets.

Functional domains of the Toxoplasma GRA2 protein in the formation of the membranous nanotubular network of the parasitophorous vacuole.

Amphipathic alpha-helices have been proposed as the general means used by soluble proteins to induce membrane tubulation. Previous studies had shown that the GRA2 dense granule protein of Toxoplasma gondii would be a crucial protein for the formation of the intravacuolar membranous nanotubular network (MNN) and that one of the functions of the MNN is to organise the parasites within the parasitophorous vacuole. GRA2 is a small protein (185 amino acids), predicted to contain three amphipathic alpha-helices (alpha1: 70-92; alpha2: 95-110 and alpha3: 119-139) when using the standard programs of secondary structure prediction.

Role of dystrophins and utrophins in platelet adhesion process.

Platelets are crucial at the site of vascular injury, adhering to the sub-endothelial matrix through receptors on their surface, leading to cell activation and aggregation to form a haemostatic plug. Platelets display focal adhesions as well as stress fibres to contract and facilitate expulsion of growth and pro-coagulant factors contained in the granules and to constrict the clot. The interaction of F-actin with different actin-binding proteins determines the properties and composition of the focal adhesions.

In-vitro model for the ultrastructural study of the formation of thrombi in human platelets.

Platelets are cell fragments with dynamic properties involved in clot formation after tissue damage. Platelet activation causes a change in shape, secretion of intracellular granules and aggregation with each other through the cytoskeleton components and biochemical changes. Platelet adhesion, considered as the major event in haemostasis, has been studied in several in-vitro and in-vivo models to evaluate the feasible thrombogenicity of some materials, the dynamics of specific receptors, as well as the effect of different buffers and inhibitors in this process.

Platelet adhesion: structural and functional diversity of short dystrophin and utrophins in the formation of dystrophin-associated-protein complexes related to actin dynamics.

Platelets are dynamic cell fragments that modify their shape during activation. Utrophin and dystrophins are minor actin-binding proteins present in muscle and non-muscle cytoskeleton. In the present study, we characterised the pattern of Dp71 isoforms and utrophin gene products by immunoblot in human platelets.

Actin, myosin, cytokeratins and spectrin are components of the guinea pig sperm nuclear matrix.

The nuclear matrix (NM) of somatic cells is an internal nuclear framework structure, with a structural function and participation in DNA replication and transcription. The NM has been described in mouse, hamster and human spermatozoa. In this study, an NM structural component of the guinea pig sperm nucleus was obtained by removing nuclear proteins and DNA from DTT-CTAB nuclei.

Identification and purification of actin from the subpellicular network of Toxoplasma gondii tachyzoites.

Toxoplasma gondii infects cells through dynamic events dependent on actin. Although the presence of cortical actin has been widely suggested, visualisation and localisation of actin filaments has not been reported. The subpellicular cytoskeleton network is a recently described structure possibly involved in the dynamic events.

2,3-butanedione monoxime (BDM), a potent inhibitor of actin-myosin interaction, induces ion and fluid transport in MDCK monolayers.

Membrane-cytoskeleton interactions have been shown to be crucial to modulate polarity, cell shape and the paracellular pathway in epithelial MDCK cell monolayers. In particular, actin organization and myosin-dependent contractility play an important role in the regulation of these functions. Participation of myosin in vectorial transport, expressed as formation of domes, was investigated in confluent monolayers of high transepithelial electrical resistance (TER) plated on non-permeable supports.

Modification of actin, myosin and tubulin distribution during cytoplasmic granule movements associated with platelet adhesion.

Background And Objectives: Cytoskeletal elements determine the changes in platelet cell shape which occur during adhesion, aggregation and release of granular contents as part of the activation process. The aim of this study was to characterize the changes in the distribution of actin filaments, myosin and tubulin molecules during several stages of platelet adhesion to glass and their association with granule displacement, as assessed by confocal microscopy.

Design And Methods: Platelets obtained from healthy donors were adhered to glass and cytoskeleton distribution was characterized and correlated to changes of cell shape and intracellular granule displacement by immunofluorescence assays and phase contrast microscopy.

Actin-related proteins in Actinobacillus pleuropneumoniae and their interactions with actin-binding proteins.

A group of prokaryotic actin-related proteins (PARP) with an Mr of 43000 was detected in Actinobacillus pleuropneumoniae. These proteins were enriched by a depolymerization/polymerization cycle, under similar conditions to those used to polymerize muscle actin, and purified by affinity chromatography on a DNase I-Sepharose column. Three isoforms of A.