ShlA toxin of Serratia induces P2Y2- and α5β1-dependent autophagy and bacterial clearance from host cells.

Serratia marcescens is an opportunistic human pathogen involved in antibiotic-resistant hospital acquired infections. Upon contact with the host epithelial cell and prior to internalization, Serratia induces an early autophagic response that is entirely dependent on the ShlA toxin. Once Serratia invades the eukaryotic cell and multiples inside an intracellular vacuole, ShlA expression also promotes an exocytic event that allows bacterial egress from the host cell without compromising its integrity.

Dynamic recycling of extracellular ATP in human epithelial intestinal cells.

Intestinal epithelial cells play important roles in the absorption of nutrients, secretion of electrolytes and food digestion. The function of these cells is strongly influenced by purinergic signalling activated by extracellular ATP (eATP) and other nucleotides. The activity of several ecto-enzymes determines the dynamic regulation of eATP.

The broad range di- and tri-nucleotide exchanger SLC35B1 displays asymmetrical affinities for ATP transport across the ER membrane.

In eukaryotic cells, uptake of cytosolic ATP into the endoplasmic reticulum (ER) lumen is critical for the proper functioning of chaperone proteins. The human transport protein SLC35B1 was recently postulated to mediate ATP/ADP exchange in the ER; however, the underlying molecular mechanisms mediating ATP uptake are not completely understood. Here, we extensively characterized the transport kinetics of human SLC35B1 expressed in yeast that was purified and reconstituted into liposomes.

Whipworm Infection Promotes Bacterial Invasion, Intestinal Microbiota Imbalance, and Cellular Immunomodulation.

Infections with are among the most common causes of intestinal parasitism in children worldwide, and the diagnosis is based on microscopic egg identification in the chronic phase of the infection. During parasitism, the adult worm of the trichurid nematode maintains its anterior region inserted in the intestinal mucosa, which causes serious damage and which may open access for gut microorganisms through the intestinal tissue. The immune-regulatory processes taking place during the evolution of the chronic infection are still not completely understood.

ATPe Dynamics in Protozoan Parasites. Adapt or Perish.

In most animals, transient increases of extracellular ATP (ATPe) are used for physiological signaling or as a danger signal in pathological conditions. ATPe dynamics are controlled by ATP release from viable cells and cell lysis, ATPe degradation and interconversion by ecto-nucleotidases, and interaction of ATPe and byproducts with cell surface purinergic receptors and purine salvage mechanisms. Infection by protozoan parasites may alter at least one of the mechanisms controlling ATPe concentration.

Plasmodium falciparum invasion and intraerythrocytic development are impaired by 2', 3'-dialdehyde adenosine.

Purine nucleotide synthesis in protozoa takes place exclusively via the purine salvage pathway and S-adenosyl-l-homocysteine hydrolase (SAHH) is an important enzyme in the Plasmodium salvage pathway which is not present in erythrocytes. Here, we describe the antimalarial effect of 2'3'-dialdehyde adenosine or oxidized adenosine (oADO), inhibitor of SAHH, on in vitro infection of human erythrocytes by P. falciparum.

POM-1 inhibits P2 receptors and exhibits anti-inflammatory effects in macrophages.

Extracellular nucleotides can modulate the immunological response by activating purinergic receptors (P2Rs) on the cell surface of macrophages, dendritic, and other immune cells. In particular, the activation of P2X7R can induce release of cytokines and cell death as well as the uptake of large molecules through the cell membrane by a mechanism still poorly understood. Polyoxotungstate-1 (POM-1) has been proposed as a potent inhibitor of ecto-nucleotidases, enzymes that hydrolyze extracellular nucleotides, regulating the activity of P2Rs.

Effects of obesity on depression: A role for inflammation and the gut microbiota.

Depression is a mental disorder associated with environmental, genetic and psychological factors. Recent studies indicate that chronic neuro-inflammation may affect brain physiology and alter mood and behavior. Consumption of a high-fat diet leads to obesity and chronic systemic inflammation.

Inhibition of ecto-ATPase activities impairs HIV-1 infection of macrophages.

Nucleotides and nucleosides are secreted into extracellular media at different concentrations as a consequence of different physiologic and pathological conditions. Ecto-nucleotidases, enzymes present on the surface of most cells, hydrolyze these extracellular nucleotides and reduce the concentration of them, thus affecting the activation of different nucleotide and nucleoside receptors. Also, ecto-nucleotidases are present in a number of microorganisms and play important roles in host-pathogen interactions.

2´,3´-Dialdehyde of ATP, ADP, and adenosine inhibit HIV-1 reverse transcriptase and HIV-1 replication.

The 2´3´-dialdehyde of ATP or oxidized ATP (oATP) is a compound known for specifically making covalent bonds with the nucleotide-binding site of several ATP-binding enzymes and receptors. We investigated the effects of oATP and other oxidized purines on HIV-1 infection and we found that this compound inhibits HIV-1 and SIV infection by blocking early steps of virus replication. oATP, oxidized ADP (oADP), and oxidized Adenosine (oADO) impact the natural activity of endogenous reverse transcriptase enzyme (RT) in cell free virus particles and are able to inhibit viral replication in different cell types when added to the cell cultures either before or after infection.

Regulation of extracellular ATP in human erythrocytes infected with Plasmodium falciparum.

In human erythrocytes (h-RBCs) various stimuli induce increases in [cAMP] that trigger ATP release. The resulting pattern of extracellular ATP accumulation (ATPe kinetics) depends on both ATP release and ATPe degradation by ectoATPase activity. In this study we evaluated ATPe kinetics from primary cultures of h-RBCs infected with P.

Inhibitors of the 5-lipoxygenase arachidonic acid pathway induce ATP release and ATP-dependent organic cation transport in macrophages.

We have previously described that arachidonic acid (AA)-5-lipoxygenase (5-LO) metabolism inhibitors such as NDGA and MK886, inhibit cell death by apoptosis, but not by necrosis, induced by extracellular ATP (ATPe) binding to P2X7 receptors in macrophages. ATPe binding to P2X7 also induces large cationic and anionic organic molecules uptake in these cells, a process that involves at least two distinct transport mechanisms: one for cations and another for anions. Here we show that inhibitors of the AA-5-LO pathway do not inhibit P2X7 receptors, as judged by the maintenance of the ATPe-induced uptake of fluorescent anionic dyes.

The enzyme NBAD-synthase plays diverse roles during the life cycle of Drosophila melanogaster.

This report shows the biochemical characterization and life cycle-dependent expression of Drosophila melanogaster N-beta-alanyldopamine synthase (NBAD-synthase or Ebony protein). This enzyme not only catalyzes the synthesis of NBAD, the main sclerotization and pigmentation precursor of insect brown cuticles, but also plays a role in brain neurotransmitter metabolism. In addition to the epidermis expression our immunodetection experiments show the novel localization of NBAD-synthase in different regions of the adult brain, in the foregut of pharate adult and, surprisingly, in the epidermis of the trachea during embryogenesis.

Expression of purinergic receptors and modulation of P2X7 function by the inflammatory cytokine IFNgamma in human epithelial cells.

The cervical epithelial cell line, HeLa, is one of the oldest and most commonly used cell lines in cell biology laboratories. Although a truncated P2X(7) receptor has recently been identified in HeLa cells, the expression of other purinergic receptors or the function of the P2X(7) protein has not been characterized. We here show that HeLa cells express transcripts for most P2X and P2Y purinergic receptors.

ATP-induced P2X7-associated uptake of large molecules involves distinct mechanisms for cations and anions in macrophages.

Macrophages express the P2X(7) receptor and other nucleotide (P2) receptors, and display the phenomenon of extracellular ATP (ATP(e))-induced P2X(7)-dependent membrane permeabilization, which occurs through a poorly understood mechanism. We used patch-clamp recordings, cytoplasmic Ca(2+) measurements and fluorescent dye uptake assays to compare P2X(7)-associated transport phenomena of macrophages and HEK-293 cells transfected with P2X(7) receptors (HEK-P2X(7) cells). Both cell types showed inward currents, increase of free cytoplasmic Ca(2+) concentration and the uptake of cationic dyes upon exposure to ATP(e), as previously described.

The role of N-beta-alanyldopamine synthase in the innate immune response of two insects.

Insects trigger a multifaceted innate immune response to fight microbial infections. We show that in the yellow mealworm, Tenebrio molitor, septic injuries induce the synthesis of N-beta-alanyldopamine (NBAD), which is known as the main sclerotization precursor of insect brown cuticles. We demonstrate that NBAD synthase is induced in the epidermis of the mealworm and of the Medfly, Ceratitis capitata, by infection with Escherichia coli.

Activation of ERK1/2 by extracellular nucleotides in macrophages is mediated by multiple P2 receptors independently of P2X7-associated pore or channel formation.

Macrophages express several P2X and P2Y nucleotide receptors and display the phenomenon of ATP-induced P2X7-dependent membrane permeabilization, which occurs through a poorly understood mechanism. Several P2 receptors are known to be coupled to the activation of mitogen-activated protein kinases (MAPKs) and Ca2+ signaling. Here, we use macrophages to investigate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) by nucleotides and the involvement of MAPKs and intracellular Ca2+ concentration in ATP-induced membrane permeabilization.

Sialic acid as a protective barrier against neointima development.

Arterial sialic acid (SA) has been shown to attenuate the binding of fibrinogen and low-density lipoproteins (LDL) to the vessel wall, presumably protecting against atherosclerosis. This study was aimed to assess the effect of changes in SA content in intimal thickening, an early step in the development of atherosclerosis. New Zealand white rabbits were subjected to bilateral carotid periarterial collaring, followed by in situ-perfusion with neuroaminidase (random artery) and with vehicle (contralateral control artery).

Constitutive activity of N-beta-alanyl-catecholamine ligase in insect brain.

N-Beta-Alanyldopamine (NBAD) is the primary catechol tanning agent precursor in typical brown or yellow insect cuticle. The insect integument enzyme responsible for the synthesis of NBAD was reported to be expressed solely in the epidermis, and only at the time of cuticle sclerotization. However, in this study we demonstrate directly that the enzyme also is expressed in a constitutive manner in the neural system of insects.