Leishmania parasites cause a variety of symptoms, including mucocutaneous leishmaniasis, which results in the destruction of the mucous membranes of the nose, mouth, and throat. The species of Leishmania carrying Leishmania RNA virus 1 (LRV1), from the family Totiviridae, are more likely to cause severe disease and are less sensitive to treatment than those that do not contain the virus. Although the importance of LRV1 for the severity of leishmaniasis was discovered a long time ago, the structure of the virus remained unknown. Here, we present a cryo-electron microscopy reconstruction of the virus-like particle of LRV1 determined to a resolution of 3.65 Å. The capsid has icosahedral symmetry and is formed by 120 copies of a capsid protein assembled in asymmetric dimers. RNA genomes of viruses from the family Totiviridae are synthetized, but not capped at the 5' end, by virus RNA polymerases. To protect viral RNAs from degradation, capsid proteins of the L-A totivirus cleave the 5' caps of host mRNAs, creating decoys to overload the cellular RNA quality control system. Capsid proteins of LRV1 form positively charged clefts, which may be the cleavage sites for the 5' cap of Leishmania mRNAs. The putative RNA binding site of LRV1 is distinct from that of the related L-A virus. The structure of the LRV1 capsid enables the rational design of compounds targeting the putative decapping site. Such inhibitors may be developed into a treatment for mucocutaneous leishmaniasis caused by LRV1-positive species of LeishmaniaIMPORTANCE Twelve million people worldwide suffer from leishmaniasis, resulting in more than 30 thousand deaths annually. The disease has several variants that differ in their symptoms. The mucocutaneous form, which leads to disintegration of the nasal septum, lips, and palate, is caused predominantly by Leishmania parasites carrying Leishmania RNA virus 1 (LRV1). Here, we present the structure of the LRV1 capsid determined using cryo-electron microscopy. Capsid proteins of a related totivirus, L-A virus, protect viral RNAs from degradation by cleaving the 5' caps of host mRNAs. Capsid proteins of LRV1 may have the same function. We show that the LRV1 capsid contains positively charged clefts that may be sites for the cleavage of mRNAs of Leishmania cells. The structure of the LRV1 capsid enables the rational design of compounds targeting the putative mRNA cleavage site. Such inhibitors may be used as treatments for mucocutaneous leishmaniasis.
The western honeybee is the primary pollinator of numerous food crops. Furthermore, honeybees are essential for ecosystem stability by sustaining the diversity and abundance of wild flowering plants. However, the worldwide population of honeybees is under pressure from environmental stress and pathogens. Viruses from the families Iflaviridae and Dicistroviridae, together with their vector, the parasitic mite Varroa destructor, are the major threat to the world's honeybees. Dicistroviruses and iflaviruses have capsids with icosahedral symmetries. Acidic pH triggers the genome release of both dicistroviruses and iflaviruses. The capsids of iflaviruses expand, whereas those of dicistroviruses remain compact until the genome release. Furthermore, dicistroviruses use inner capsid proteins, whereas iflaviruses employ protruding domains or minor capsid proteins from the virion surface to penetrate membranes and deliver their genomes into the cell cytoplasm. The structural characterization of the infection process opens up possibilities for the development of antiviral compounds.
- MeSH
- Genome, Viral * MeSH
- Capsid chemistry metabolism MeSH
- Hydrogen-Ion Concentration MeSH
- Protein Conformation MeSH
- Crystallography, X-Ray MeSH
- Acids MeSH
- Models, Molecular MeSH
- RNA Viruses metabolism MeSH
- Bees virology MeSH
- Virion chemistry genetics MeSH
- Virus Diseases veterinary MeSH
- Capsid Proteins chemistry MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Members of the fibroblast growth factor (FGF) family have myriad functions during development of both non-vertebrate and vertebrate organisms. One of these family members, FGF10, is largely expressed in mesenchymal tissues and is essential for postnatal life because of its critical role in development of the craniofacial complex, as well as in lung branching. Here, we review the function of FGF10 in morphogenesis of craniofacial organs. Genetic mouse models have demonstrated that the dysregulation or absence of FGF10 function affects the process of palate closure, and FGF10 is also required for development of salivary and lacrimal glands, the inner ear, eye lids, tongue taste papillae, teeth, and skull bones. Importantly, mutations within the FGF10 locus have been described in connection with craniofacial malformations in humans. A detailed understanding of craniofacial defects caused by dysregulation of FGF10 and the precise mechanisms that underlie them offers new opportunities for development of medical treatments for patients with birth defects and for regenerative approaches for cancer patients with damaged gland tissues.
- Publication type
- Journal Article MeSH
- Review MeSH
Infection by sacbrood virus (SBV) from the family Iflaviridae is lethal to honey bee larvae but only rarely causes the collapse of honey bee colonies. Despite the negative effect of SBV on honey bees, the structure of its particles and mechanism of its genome delivery are unknown. Here we present the crystal structure of SBV virion and show that it contains 60 copies of a minor capsid protein (MiCP) attached to the virion surface. No similar MiCPs have been previously reported in any of the related viruses from the order Picornavirales. The location of the MiCP coding sequence within the SBV genome indicates that the MiCP evolved from a C-terminal extension of a major capsid protein by the introduction of a cleavage site for a virus protease. The exposure of SBV to acidic pH, which the virus likely encounters during cell entry, induces the formation of pores at threefold and fivefold axes of the capsid that are 7 Å and 12 Å in diameter, respectively. This is in contrast to vertebrate picornaviruses, in which the pores along twofold icosahedral symmetry axes are currently considered the most likely sites for genome release. SBV virions lack VP4 subunits that facilitate the genome delivery of many related dicistroviruses and picornaviruses. MiCP subunits induce liposome disruption in vitro, indicating that they are functional analogs of VP4 subunits and enable the virus genome to escape across the endosome membrane into the cell cytoplasm.
- MeSH
- Endosomes chemistry metabolism virology MeSH
- Genome, Viral * MeSH
- Crystallography, X-Ray MeSH
- RNA Viruses * chemistry metabolism MeSH
- Bees virology MeSH
- Virion * chemistry metabolism MeSH
- Capsid Proteins * chemistry metabolism MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Trypanosoma brucei is an extracellular parasite that alternates between an insect vector (procyclic form) and the bloodstream of a mammalian host (bloodstream form). While it was previously reported that mitochondrial release factor 1 (TbMrf1) is essential in cultured procyclic form cells, we demonstrate here that in vitro bloodstream form cells can tolerate the elimination of TbMrf1. Therefore, we explored if this discrepancy is due to the unique bioenergetics of the parasite since procyclic form cells rely on oxidative phosphorylation; whereas bloodstream form cells utilize glycolysis for ATP production and FoF1-ATPase to maintain the essential mitochondrial membrane potential. The observed disruption of intact bloodstream form FoF1-ATPases serves as a proxy to indicate that the translation of its mitochondrially encoded subunit A6 is impaired without TbMrf1. While these null mutants have a decreased mitochondrial membrane potential, they have adapted by increasing their dependence on the electrogenic contributions of the ADP/ATP carrier to maintain the mitochondrial membrane potential above the minimum threshold required for T. brucei viability in vitro. However, this inefficient compensatory mechanism results in avirulent mutants in mice. Finally, the depletion of the codon-independent release factor TbPth4 in the TbMrf1 knockouts further exacerbates the characterized mitchondrial phenotypes.
- MeSH
- Adaptation, Physiological * MeSH
- Membrane Potential, Mitochondrial genetics MeSH
- Mitochondrial Proteins genetics metabolism MeSH
- Mitochondria * genetics metabolism MeSH
- Mice, Inbred BALB C MeSH
- Mice MeSH
- Oxidative Phosphorylation MeSH
- Proton-Translocating ATPases genetics metabolism MeSH
- Protozoan Proteins genetics metabolism MeSH
- Life Cycle Stages * MeSH
- Trypanosoma brucei brucei * genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The patterning of repeated structures is a major theme in developmental biology, and the inter-relationship between spacing and size of such structures is an unresolved issue. Fungiform papillae are repeated epithelial structures that house taste buds on the anterior tongue. Here, we report that FGF signaling is a crucial regulator of fungiform papillae development. We found that mesenchymal FGF10 controls the size of the papillary area, while overall patterning remains unchanged. Our results show that FGF signaling negatively affects the extent of canonical Wnt signaling, which is the main activation pathway during fungiform papillae development; however, this effect does not occur at the level of gene transcription. Rather, our experimental data, together with computational modeling, indicate that FGF10 modulates the range of Wnt effects, likely via induction of Sostdc1 expression. We suggest that modification of the reach of Wnt signaling could be due to local changes in morphogen diffusion, representing a novel mechanism in this tissue context, and we propose that this phenomenon might be involved in a broader array of mammalian developmental processes.
- MeSH
- Models, Biological MeSH
- Taste Buds embryology metabolism MeSH
- Fibroblast Growth Factor 10 deficiency genetics metabolism MeSH
- Intracellular Signaling Peptides and Proteins deficiency genetics metabolism MeSH
- Bone Morphogenetic Proteins genetics metabolism MeSH
- Membrane Proteins deficiency genetics metabolism MeSH
- Mice, Knockout MeSH
- Mice, Transgenic MeSH
- Mice MeSH
- Computer Simulation MeSH
- Hedgehog Proteins genetics metabolism MeSH
- Body Patterning genetics physiology MeSH
- Wnt Signaling Pathway * MeSH
- Pregnancy MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Mice MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Knowledge on the involvement of spinal COX-1 and COX-2 in pain due to osteoarthritis could be useful for better understanding of its pathogenesis and therapy. In this study we have investigated a long-term pattern of expression and production of spinal COX-1 and COX-2 in the model of osteoarthritis induced in rats by injection of monoiodoacetate (MIA) into the knee joint. MIA injection produced thermal hyperalgesia (assessed by the plantar test) and tactile allodynia (measured with von Frey hairs). The pain measures reached maximum on the fifht day, then remained relatively stable. The expression of spinal COX-2 mRNA reached maximum on day 5 (5.2 times; P<0.001) and remained increased until day 31 (4.9 times; P<0.001). Expression of spinal COX-1 mRNA increased gradually reaching maximum on the day 31 (4.5 times; P<0.001) when the relative expression of both genes was almost equal. The production of both proteins was almost similar at the beginning of the experiment. The highest production of COX-2 protein was observed on day 5 after the induction of osteoarthritis (increased 3.9 times). The levels of COX-1 protein increased gradually with maximum on day 31 (3.4 times). The present findings indicate that not only expression of COX-2 mRNA but also that of COX-1 mRNA is significantly increased in the spine during osteoarthritis pain. Thus, in contrast to inflammatory pain, the upregulation of spinal COX-1 may be important in osteoarthritis pain.
- MeSH
- Osteoarthritis, Knee enzymology genetics chemically induced MeSH
- Pain epidemiology genetics chemically induced MeSH
- Time Factors MeSH
- Cyclooxygenase 1 biosynthesis genetics MeSH
- Cyclooxygenase 2 biosynthesis genetics MeSH
- Enzyme Induction MeSH
- Financing, Organized MeSH
- Hyperalgesia enzymology genetics chemically induced MeSH
- Rats MeSH
- Iodoacetic Acid MeSH
- Membrane Proteins biosynthesis genetics MeSH
- Pain Measurement MeSH
- RNA, Messenger MeSH
- Spinal Cord enzymology MeSH
- Disease Models, Animal MeSH
- Rats, Wistar MeSH
- Pain Threshold MeSH
- Reaction Time MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
Levels of cyclooxygenase-2 (COX-2) mRNA, but not those of COX-1, were reported to be raised significantly after peripheral inflammation in the rat spinal cord. The aim of the present study was to ascertain whether this pattern of COX-2 and COX-1 expression applies also to other pain conditions induced by surgical procedure. Experiments were performed on two types of pain models. In a model of postoperative pain, 1 cm longitudinal incision was made through skin, fascia and muscle of the plantar aspect of the right hind paw in anaesthetized rats. In the second model, peripheral inflammation was induced by unilateral, intraplantar injection of carrageenan in the right hind paw. Carrageenan injection or skin incision produced marked and significant reduction of paw withdrawal latencies to noxious radiant heat stimuli after 2 and 6 hr. Under the acute inflammation 2 and 6 hr after carrageenan injection levels of COX-2 mRNA were markedly raised (7.8 and 15.5 times; P<0.001, respectively) while spinal levels of COX-1 mRNA were not significantly altered (n.s.). In contrast, spinal levels of COX-2 mRNA were raised less markedly in a model of postoperative pain (4.9 times at 2 hr; P<0.001 and 2.9 times (n.s.) at 6 hr after surgery) whilst levels of COX-1 mRNA in the lumbar spine were increased significantly (2.3 times; P<0.001) 6 hr after surgery. The present findings indicate that expression of COX-2 mRNA in the spine is less dominant in postoperative pain than in inflammatory pain and that spinal COX-1 mRNA is upregulated in postoperative pain.
- MeSH
- Cyclooxygenase 1 genetics MeSH
- Cyclooxygenase 2 genetics MeSH
- Gene Expression genetics MeSH
- Financing, Organized MeSH
- Carrageenan administration & dosage toxicity MeSH
- Rats MeSH
- Pain Measurement methods MeSH
- RNA, Messenger genetics metabolism MeSH
- Spinal Cord enzymology metabolism MeSH
- Disease Models, Animal MeSH
- Reverse Transcriptase Polymerase Chain Reaction methods MeSH
- Pain, Postoperative enzymology genetics physiopathology MeSH
- Rats, Wistar MeSH
- Up-Regulation genetics MeSH
- Hindlimb enzymology surgery metabolism MeSH
- Inflammation enzymology genetics chemically induced MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
Epidemiologické studie na mnohatisícových souborech osob ukázaly, že samotné selektivní inhibitory zpětného vychytávání serotoninu poněkud zvyšují riziko krvácení (např. do gastrointestinálního traktu asi l,5-3krát). Riziko krvácení z horní části gastrointestinálního traktu po samotných selektivních inhibitorech zpětného vychytávání serotoninu není sice příliš vysoké (asi u 1 z 1300 léčených), ale při kombinaci selektivních inhibitorů zpětného vychytávání serotoninu s nesteroidními antiflogistiky se riziko gastrointestinálního krvácení může zvýšit až 15krát. Riziko se zvyšuje zejména u seniorů, u osob s vředovou nemocí a při krvácení do gastrointestinálního traktu v anamnéze. U osob se zvýšeným rizikem se doporučuje dávat přednost méně selektivním inhibitorům zpětného vychytávání serotoninu a při kombinaci s nesteroidními antiflogistiky chránit žaludek antisekrečními léky (např. inhibitory protonové pumpy). Při současném podávání selektivních inhibitorů zpětného vychytávání serotoninu a malých dávek aspirinu se riziko krvácení z gastrointestinálního traktu zvyšuje asi 5-7krát. Velmi vzácně se mohou vyskytnout i úmrtí pro krvácení z gastrointestinálního traktu po selektivních inhibitorech zpětného vychytávání serotoninu samotných nebo v kombinaci s nesteroidními antiflogistiky. Mechanismus zvýšeného krvácení po selektivních inhibitorech zpětného vychytávání serotoninu není zatím objasněn. Přepokládá se, že se v něm uplatňuje inhibice agregace trombocytů pro depleci serotoninu vlivem selektivních inhibitorů zpětného vychytávání serotoninu. Zvýšené krvácení do gastrointestinálního traktu při kombinaci selektivních inhibitorů zpětného vychytávání serotoninu s nesteroidními antiflogistiky je vysvětlováno adicí inhibice destičkové agregace vlivem nesteroidních antiflogistik a žaludeční iritací po nesteroidních antiflogisticích.
Epidemiological studies in large cohorts of patients indicate that selective serotonin reuptake inhibitors may moderately increase the risk of bleeding (e.g. 1.5-3 times for upper gastrointestinal bleeding). Although the incidence of upper gastrointestinal bleeding after selective serotonin reuptake inhibitors alone may appear relatively low (estimated in 1 of 1300 patients), the risk of gastrointestinal bleeding may increase markedly when selective serotonin reuptake inhibitors are combined with non-steroidal anti-inflammatory drugs. Most at risk are the elderly and those with previous ulcers or gastrointestinal bleeding. In these patients, it is recommended to use non-selective serotonin reuptake inhibitors and in selective serotonin reuptake inhibitors + non-steroidal anti-inflammatory drugs comedication to use gastroprotective agents (e.g. proton pump inhibitors). Combined use of a selective serotonin reuptake inhibitor and low-dose aspirin increases the risk of gastrointestinal bleeding 5 -7 times. Fatalities due to upper gastrointestinal bleeding after selective serotonin reuptake inhibitors alone or in combination with non-steroidal anti-inflammatory drugs occur very rarely. Mechanism of increased bleeding after selective serotonin reuptake inhibitors is not fully understood. It is assumed that depletion of serotonin from platelets due to selective serotonin reuptake inhibitors is involved. The increased upper gastrointestinal bleeding after a combined use of selective serotonin reuptake inhibitors with non-steroidal an ti-inflammatory drugs might be due to addition of inhibitory effects of these drugs on platelet aggregation and a gastric mucose irritation produced by non-steroidal anti-inflammatory drugs.
