scholarly journals Thiosemicarbazone Copper Chelator BLT-1 Blocks Apicomplexan Parasite Replication by Selective Inhibition of Scavenger Receptor B Type 1 (SR-BI)

2021 ◽  
Vol 9 (11) ◽  
pp. 2372
Author(s):  
Camilo Larrazabal ◽  
Sara López-Osorio ◽  
Zahady D. Velásquez ◽  
Carlos Hermosilla ◽  
Anja Taubert ◽  
...  
Keyword(s):  
De Novo ◽  
Neospora Caninum ◽  
Scavenger Receptor ◽  
Selective Inhibition ◽  
Current Data ◽  
Host Cells ◽  
Besnoitia Besnoiti ◽  
Replication Process ◽  
Ldl Particles

Coccidian parasites are obligate intracellular pathogens that affect humans and animals. Apicomplexans are defective in de novo synthesis of cholesterol, which is required for membrane biosynthesis and offspring formation. In consequence, cholesterol has to be scavenged from host cells. It is mainly taken up from extracellular sources via LDL particles; however, little is known on the role of HDL and its receptor SR-BI in this process. Here, we studied effects of the SR-BI-specific blocker BLT-1 on the development of different fast (Toxoplasma gondii, Neospora caninum, Besnoitia besnoiti) and slow (Eimeria bovis and Eimeria arloingi) replicating coccidian species. Overall, development of all these parasites was significantly inhibited by BLT-1 treatment indicating a common SR-BI-related key mechanism in the replication process. However, SR-BI gene transcription was not affected by T. gondii, N. caninum and B. besnoiti infections. Interestingly, BLT-1 treatment of infective stages reduced invasive capacities of all fast replicating parasites paralleled by a sustained increase in cytoplasmic Ca++ levels. Moreover, BLT1-mediated blockage of SR-BI led to enhanced host cell lipid droplet abundance and neutral lipid content, thereby confirming the importance of this receptor in general lipid metabolism. Finally, the current data suggest a conserved role of SR-BI for successful coccidian infections.

scholarly journals Biotinylation of the Neospora caninum parasitophorous vacuole reveals novel dense granule proteins

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Congshan Yang ◽  
Chenrong Wang ◽  
Jing Liu ◽  
Qun Liu
Keyword(s):  
Neospora Caninum ◽  
Gene Knockout ◽  
Parasitophorous Vacuole ◽  
Dense Granule ◽  
Host Cells ◽  
Spectrometric Analysis ◽  
Data Set ◽  
Dense Granules ◽  
Granule Proteins

Abstract Background Neospora caninum is an obligate intracellular parasite that invades host cells and replicates within the parasitophorous vacuole (PV), which resists fusion with host cell lysosomal compartments. To modify the PV, the parasite secretes an array of proteins, including dense granule proteins (GRAs). The vital role of GRAs in the Neospora life cycle cannot be overestimated. Despite this important role, only a subset of these proteins have been identified, and most of their functions have not been elucidated. Our previous study demonstrated that NcGRA17 is specifically targeted to the delimiting membrane of the parasitophorous vacuole membrane (PVM). In this study, we utilize proximity-dependent biotin identification (BioID) to identify novel components of the dense granules. Methods NcGRA17 was BirA* epitope-tagged in the Nc1 strain utilizing the CRISPR/Cas9 system to create a fusion of NcGRA17 with the biotin ligase BirA*. The biotinylated proteins were affinity-purified for mass spectrometric analysis, and the candidate GRA proteins from BioID data set were identified by gene tagging. To verify the biological role of novel identified GRA proteins, we constructed the NcGRA23 and NcGRA11 (a–e) knockout strains using the CRISPR/Cas9 system and analyzed the phenotypes of these mutants. Results Using NcGRA17-BirA* fusion protein as bait, we have identified some known GRAs and verified localization of 11 novel GRA proteins by gene endogenous tagging or overexpression in the Nc1 strain. We proceeded to functionally characterize NcGRA23 and NcGRA11 (a–e) by gene knockout. The lack of NcGRA23 or NcGRA11 (a–e) did not affect the parasite propagation in vitro and virulence in vivo. Conclusions In summary, our findings reveal that BioID is effective in discovering novel constituents of N. caninum dense granules. The exact biological functions of the novel GRA proteins are yet unknown, but this could be explored in future studies. Graphical abstract

scholarly journals A data-driven approach to identify risk profiles and protective drugs in COVID-19

2020 ◽  
Vol 118 (1) ◽  
pp. e2016877118
Author(s):  
Pietro E. Cippà ◽  
Federica Cugnata ◽  
Paolo Ferrari ◽  
Chiara Brombin ◽  
Lorenzo Ruinelli ◽  
...  
Keyword(s):  
Risk Factors ◽  
De Novo ◽  
Controlled Trial ◽  
Host Cells ◽  
Hospital Death ◽  
Dependency Structure ◽  
Risk Of Death ◽  
Data Driven Approach ◽  
Highly Correlated

As the COVID-19 pandemic is spreading around the world, increasing evidence highlights the role of cardiometabolic risk factors in determining the susceptibility to the disease. The fragmented data collected during the initial emergency limited the possibility of investigating the effect of highly correlated covariates and of modeling the interplay between risk factors and medication. The present study is based on comprehensive monitoring of 576 COVID-19 patients. Different statistical approaches were applied to gain a comprehensive insight in terms of both the identification of risk factors and the analysis of dependency structure among clinical and demographic characteristics. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus enters host cells by binding to the angiotensin-converting enzyme 2 (ACE2), but whether or not renin−angiotensin−aldosterone system inhibitors (RAASi) would be beneficial to COVID-19 cases remains controversial. The survival tree approach was applied to define a multilayer risk stratification and better profile patient survival with respect to drug regimens, showing a significant protective effect of RAASi with a reduced risk of in-hospital death. Bayesian networks were estimated, to uncover complex interrelationships and confounding effects. The results confirmed the role of RAASi in reducing the risk of death in COVID-19 patients. De novo treatment with RAASi in patients hospitalized with COVID-19 should be prospectively investigated in a randomized controlled trial to ascertain the extent of risk reduction for in-hospital death in COVID-19.

scholarly journals Hepatitis C virus cell entry: role of lipoproteins and cellular receptors

2009 ◽  
Vol 90 (5) ◽  
pp. 1055-1070 ◽  
Author(s):  
Michela E. Burlone ◽  
Agata Budkowska
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Current Knowledge ◽  
Scavenger Receptor ◽  
Cell Entry ◽  
Host Cells ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Junction Molecules

Hepatitis C virus (HCV), a major cause of chronic liver disease, is a single-stranded positive sense virus of the family Flaviviridae. HCV cell entry is a multi-step process, involving several viral and cellular factors that trigger virus uptake into the hepatocyte. Tetraspanin CD81, human scavenger receptor SR-BI, and tight junction molecules Claudin-1 and occludin are the main receptors that mediate HCV entry. In addition, the virus may use glycosaminoglycans and/or low density receptors on host cells as initial attachment factors. A unique feature of HCV is the dependence of virus replication and assembly on host cell lipid metabolism. Most notably, during HCV assembly and release from the infected cells, virus particles associate with lipids and very-low-density lipoproteins. Thus, infectious virus circulates in patient sera in the form of triglyceride-rich particles. Consequently, lipoproteins and lipoprotein receptors play an essential role in virus uptake and the initiation of infection. This review summarizes the current knowledge about HCV receptors, mechanisms of HCV cell entry and the role of lipoproteins in this process.

scholarly journals The Role of Mcl-1 inS. aureus-Induced Cytoprotection of Infected Macrophages

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Joanna Koziel ◽  
Katarzyna Kmiecik ◽  
Daniela Chmiest ◽  
Katarzyna Maresz ◽  
Danuta Mizgalska ◽  
...  
Keyword(s):  
De Novo ◽  
Myeloid Cell ◽  
Underlying Mechanism ◽  
Host Cells ◽  
Intracellular Pathogen ◽  
Dependent Inhibition ◽  
Infected Cells ◽  
The Stability

As a facultative intracellular pathogen,Staphylococcus aureusinvades macrophages and then promotes the cytoprotection of infected cells thus stabilizing safe niche for silent persistence. This process occurs through the upregulation of crucial antiapoptotic genes, in particular,myeloid cell leukemia-1 (MCL-1). Here, we investigated the underlying mechanism and signal transduction pathways leading to increasedMCL-1expression in infected macrophages. LiveS. aureusnot only stimulatedde novosynthesis of Mcl-1, but also prolonged the stability of this antiapoptotic protein. Consistent with this, we proved a crucial role of Mcl-1 inS. aureus-induced cytoprotection, since silencing ofMCL1by siRNA profoundly reversed the cytoprotection of infected cells leading to apoptosis. IncreasedMCL1expression in infected cells was associated with enhanced NFκB activation and subsequent IL-6 secretion, since the inhibition of both NFκB and IL-6 signalling pathways abrogated Mcl-1 induction and cytoprotection. Finally, we confirmed our observationin vivoin murine model of septic arthritis showing the association between the severity of arthritis and Mcl-1 expression. Therefore, we propose thatS. aureusis hijacking the Mcl-1-dependent inhibition of apoptosis to prevent the elimination of infected host cells, thus allowing the intracellular persistence of the pathogen, its dissemination by infected macrophages, and the progression of staphylococci diseases.

scholarly journals Vitamin D Status of Mice Deficient in Scavenger Receptor Class B Type 1, Cluster Determinant 36 and ATP-Binding Cassette Proteins G5/G8

Nutrients ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2169
Author(s):  
Mikis Kiourtzidis ◽  
Julia Kühn ◽  
Corinna Brandsch ◽  
Gabriele I. Stangl
Keyword(s):  
Vitamin D ◽  
Vitamin D3 ◽  
Scavenger Receptor ◽  
Current Data ◽  
Vitamin D Levels ◽  
Class B ◽  
Liver And Kidney ◽  
Lipid Transporters

Classical lipid transporters are suggested to modulate cellular vitamin D uptake. This study investigated the vitamin D levels in serum and tissues of mice deficient in SR-B1 (Srb1-/-), CD36 (Cd36-/-) and ABC-G5/G8 (Abcg5/g8-/-) and compared them with corresponding wild-type (WT) mice. All mice received triple-deuterated vitamin D3 (vitamin D3-d3) for six weeks. All knockout mice vs. WT mice showed specific alterations in their vitamin D concentrations. Srb1-/- mice had higher levels of vitamin D3-d3 in the serum, adipose tissue, kidney and heart, whereas liver levels of vitamin D3-d3 remained unaffected. Additionally, Srb1-/- mice had lower levels of deuterated 25-hydroxyvitamin D3 (25(OH)D3-d3) in the serum, liver and kidney compared to WT mice. In contrast, Cd36-/- and WT mice did not differ in the serum and tissue levels of vitamin D3-d3, but Cd36-/- vs. WT mice were characterized by lower levels of 25(OH)D3-d3 in the serum, liver and kidney. Finally, Abcg5/g8-/- mice tended to have higher levels of vitamin D3-d3 in the serum and liver. Major alterations in Abcg5/g8-/- mice were notably higher levels of 25(OH)D3-d3 in the serum and kidney, accompanied by a higher hepatic mRNA abundance of Cyp27a1 hydroxylase. To conclude, the current data emphasize the significant role of lipid transporters in the uptake, tissue distribution and activation of vitamin D.

scholarly journals The Phospholipid Profile of Mycoplasmas

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jonathan D. Kornspan ◽  
Shlomo Rottem
Keyword(s):  
Molecular Mechanisms ◽  
De Novo ◽  
Inflammatory Responses ◽  
Polar Lipids ◽  
Host Cells ◽  
Eukaryotic Cells ◽  
Ether Lipids ◽  
Mycoplasma Cell ◽  
Phospholipid Profile

Thede novosynthesized polar lipids ofMycoplasmaspecies are rather simple, comprising primarily of the acidic glycerophospholipids PG and CL. In addition, when grown in a medium containing serum, significant amounts of PC and SPM are incorporated into the mycoplasma cell membrane although these lipids are very uncommon in wall-covered bacteria. The exogenous lipids are either incorporated unchanged or the PC incorporated is modified by a deacylation-acylation enzymatic cycle to form disaturated PC. Although their small genome, in someMycoplasmaspecies, other genes involved in lipid biosynthesis were detected, resulting in the synthesis of a variety of glycolipis, phosphoglycolipids and ether lipids. We suggest that analyses and comparisons of mycoplasma polar lipids may serve as a novel and useful tool for classification. Nonetheless, to evaluate the importance of polar lipids in mycoplasma, further systematic and extensive studies on moreMycoplasmaspecies are needed. While studies are needed to elucidate the role of lipids in the mechanisms governing the interaction of mycoplasmas with host eukaryotic cells, the finding that a terminal phosphocholine containing glycolipids ofM. fermentansserves both as a major immune determinants and as a trigger of the inflammatory responses, and the findings that the fusogenicity ofM. fermentanswith host cells is markedly stimulated by lyso-ether lipids, are important steps toward understanding the molecular mechanisms ofM. fermentanspathogenicity.

scholarly journals Endoplasmic Reticulum and cis-Golgi Localization of Human T-Lymphotropic Virus Type 1 p12I: Association with Calreticulin and Calnexin

2001 ◽  
Vol 75 (16) ◽  
pp. 7672-7682 ◽  
Author(s):  
Wei Ding ◽  
Björn Albrecht ◽  
Rushu Luo ◽  
Weiqing Zhang ◽  
James R. L. Stanley ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Virus Type ◽  
Cell Activation ◽  
Protein Transport ◽  
De Novo ◽  
Rabbit Model ◽  
Host Cells ◽  
T Lymphotropic Virus

ABSTRACT Human T-lymphotropic virus type 1 (HTLV-1) is a complex retrovirus encoding regulatory and accessory genes in four open reading frames (ORF I to IV) of the pX region. We have demonstrated an important role of pX ORF I expression, which encodes p12I, in establishment of HTLV-1 infection in a rabbit model and for optimal viral infectivity in quiescent primary lymphocytes. These data indicated that p12I may enhance lymphocyte activation and thereby promote virus infection. To further define the role of p12I in cell activation, we characterized the subcellular localization of p12I in transfected 293T cells and HeLa-Tat cells by multiple methods, including immunofluorescence confocal microscopy, electron microscopy, and subcellular fractionation. Herein, we demonstrate that p12I accumulates in the endoplasmic reticulum (ER) and cis-Golgi apparatus. The location of p12I was unchanged following treatments with both cycloheximide (blocking de novo protein synthesis) and brefeldin A (disrupting ER-to-Golgi protein transport), indicating that the protein is retained in the ER and cis-Golgi. Moreover, using coimmunoprecipitation assays, we identify the direct binding of p12I with both calreticulin and calnexin, resident ER proteins which regulate calcium storage. Our results indicate that p12I directly binds key regulatory proteins involved in calcium-mediated cell signaling and suggest a role of p12Iin the establishment of HTLV-1 infection by activation of host cells.

scholarly journals ToxoplasmaRhoptries: Unique Secretory Organelles and Source of Promising Vaccine Proteins for Immunoprevention of Toxoplasmosis

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Henryka Dlugonska
Keyword(s):  
Neospora Caninum ◽  
Parasitophorous Vacuole ◽  
Protozoan Parasite ◽  
Current Data ◽  
Intracellular Killing ◽  
Apicomplexan Parasites ◽  
Obligate Intracellular ◽  
Animal Pathogens ◽  
Intracellular Protozoan Parasite

Toxoplasma gondiiis an obligate intracellular protozoan parasite classified in the phylum Apicomplexa, which includes numerous notable human and animal pathogens (Plasmodiumspecies,Cryptosporidiumspecies,Neospora caninum, etc.). The invasive stages of apicomplexans are characterized by the presence of an apical complex composed of specialized cytoskeletal and secretory organelles, including rhoptries. Rhoptries, unique apical secretory organelles shared exclusively by all apicomplexan parasites, are known to be involved in an active parasite's penetration into the host cell associated with the biogenesis of specific intracellular compartment, parasitophorous vacuole in which the parasite multiplies intensively, avoiding intracellular killing. Due to the key biological role of rhoptries, rhoptry proteins have recently become vaccine candidates for the prevention of several parasitoses, toxoplasmosis among them. The article presents current data onT. gondiirhoptries biology and new approaches to the development of effective vaccines against toxoplasmosis using rhoptry antigens.

scholarly journals Entry of Herpes Simplex Virus 1 into Epidermis and Dermal Fibroblasts Is Independent of the Scavenger Receptor MARCO

2018 ◽  
Vol 92 (15) ◽  
Author(s):  
Katharina Thier ◽  
Maureen Möckel ◽  
Katja Palitzsch ◽  
Katinka Döhner ◽  
Beate Sodeik ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Scavenger Receptor ◽  
Dermal Fibroblasts ◽  
Host Cells ◽  
Herpes Simplex Virus 1 ◽  
Skin Cells ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT To enter host cells, herpes simplex virus 1 (HSV-1) initially attaches to cell surface glycosaminoglycans, followed by the requisite binding to one of several cellular receptors, leading to viral internalization. Although virus-receptor interactions have been studied in various cell lines, the contributions of individual receptors to uptake into target tissues such as mucosa, skin, and cornea are not well understood. We demonstrated that nectin-1 acts as a major receptor for HSV-1 entry into murine epidermis, while herpesvirus entry mediator (HVEM) can serve as an alternative receptor. Recently, the macrophage receptor with collagenous structure (MARCO) has been described to mediate adsorption of HSV-1 to epithelial cells. Here, we investigated the impact of MARCO on the entry process of HSV-1 into the two major cell types of skin, keratinocytes in the epidermis and fibroblasts in the underlying dermis. Using ex vivo infection of murine epidermis, we showed that HSV-1 entered basal keratinocytes of MARCO−/− epidermis as efficiently as those of control epidermis. In addition, entry into dermal fibroblasts was not impaired in the absence of MARCO. When we treated epidermis, primary keratinocytes, or fibroblasts with poly(I), a ligand for class A scavenger receptors, HSV-1 entry was strongly reduced. As we also observed reducing effects of poly(I) in the absence of both MARCO and scavenger receptor A1, we concluded that the inhibitory effects of poly(I) on HSV-1 infection are not directly linked to class A scavenger receptors. Overall, our results support that HSV-1 entry into skin cells is independent of MARCO. IMPORTANCE During entry into its host cells, the human pathogen herpes simplex virus (HSV) interacts with various cellular receptors. Initially, receptor interaction can mediate cellular adsorption, followed by receptor binding that triggers viral internalization. The intriguing question is which receptors are responsible for the various steps during entry into the natural target tissues of HSV? Previously, we demonstrated the role of nectin-1 as a major receptor and that of HVEM as an alternative receptor for HSV-1 to invade murine epidermis. As MARCO has been described to promote infection in skin, we explored the predicted role of MARCO as a receptor that mediates adsorption to epithelial cells. Our infection studies of murine skin cells indicate that the absence of MARCO does not interfere with the efficiency of HSV-1 entry and that the inhibitory effect on viral adsorption by poly(I), a ligand of MARCO, is independent of MARCO.

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