scholarly journals Golgi Reassembly and Stacking Protein (GRASP) Participates in Vesicle-Mediated RNA Export in Cryptococcus Neoformans

Genes ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 400 ◽  
Author(s):  
Roberta Peres da Silva ◽  
Sharon de Toledo Martins ◽  
Juliana Rizzo ◽  
Flavia C. G. dos Reis ◽  
Luna S. Joffe ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Species ◽  
Eukaryotic Cells ◽  
Autophagosome Formation ◽  
Rna Content ◽  
Mrna Content ◽  
Unconventional Secretion ◽  
Rna Export ◽  
Non Coding Rnas ◽  
Polysaccharide Secretion

Golgi reassembly and stacking protein (GRASP) is required for polysaccharide secretion and virulence in Cryptococcus neoformans. In fungal species, extracellular vesicles (EVs) participate in the export of polysaccharides, proteins and RNA. In the present work, we investigated if EV-mediated RNA export is functionally connected with GRASP in C. neoformans using a graspΔ mutant. Since GRASP-mediated unconventional secretion involves autophagosome formation in yeast, we included the atg7Δ mutant with defective autophagic mechanisms in our analysis. All fungal strains exported EVs but deletion of GRASP or ATG7 profoundly affected vesicular dimensions. The mRNA content of the graspΔ EVs differed substantially from that of the other two strains. The transcripts associated to the endoplasmic reticulum were highly abundant transcripts in graspΔ EVs. Among non-coding RNAs (ncRNAs), tRNA fragments were the most abundant in both mutant EVs but graspΔ EVs alone concentrated 22 exclusive sequences. In general, our results showed that the EV RNA content from atg7Δ and WT were more related than the RNA content of graspΔ, suggesting that GRASP, but not the autophagy regulator Atg7, is involved in the EV export of RNA. This is a previously unknown function for a key regulator of unconventional secretion in eukaryotic cells.

Alpha-actin and cytochrome c mRNAs in atrophied adult rat skeletal muscle

1988 ◽  
Vol 254 (5) ◽  
pp. C651-C656 ◽  
Author(s):  
P. Babij ◽  
F. W. Booth
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Muscle Atrophy ◽  
Weight Bearing ◽  
Skeletal Muscle Atrophy ◽  
Rna Content ◽  
Mrna Content ◽  
Fast Twitch Muscle ◽  
Alpha Actin ◽  
Fast Twitch

Specific complementary DNA (cDNA) hybridization probes were used to estimate the levels of alpha-actin and cytochrome c mRNAs and also 18S rRNA in three models of skeletal muscle atrophy. After 7 days of hindlimb suspension, or immobilization, or denervation, protein content decreased 26-32% in all muscles studied except suspended fast-twitch muscle, which lost only half as much protein. alpha-Actin mRNA content decreased 51-66% and cytochrome c mRNA content decreased 42-61% in slow- and fast-twitch muscles in all three models of atrophy. However, total RNA content did not show similar directional changes; RNA content decreased 27-44% in suspended and immobilized muscle but was unchanged in denervated fast-twitch muscle. The results were interpreted to suggest that loss of weight-bearing function of skeletal muscle is a major factor affecting the levels of alpha-actin and cytochrome c mRNAs during muscle atrophy.

Non-coding RNAs and complex distributed genetic networks

Open Physics ◽  
2011 ◽  
Vol 9 (4) ◽  
Author(s):  
Vladimir Zhdanov
Keyword(s):  
Kinetic Model ◽  
Mean Field ◽  
Genetic Network ◽  
Distributed Networks ◽  
Genetic Networks ◽  
Eukaryotic Cells ◽  
New Paradigm ◽  
Non Coding Rnas ◽  
The Difference ◽  
Complex Features

AbstractIn eukaryotic cells, the mRNA-protein interplay can be dramatically influenced by non-coding RNAs (ncRNAs). Although this new paradigm is now widely accepted, an understanding of the effect of ncRNAs on complex genetic networks is lacking. To clarify what may happen in this case, we propose a mean-field kinetic model describing the influence of ncRNA on a complex genetic network with a distributed architecture including mutual protein-mediated regulation of many genes transcribed into mRNAs. ncRNA is considered to associate with mRNAs and inhibit their translation and/or facilitate degradation. Our results are indicative of the richness of the kinetics under consideration. The main complex features are found to be bistability and oscillations. One could expect to find kinetic chaos as well. The latter feature has however not been observed in our calculations. In addition, we illustrate the difference in the regulation of distributed networks by mRNA and ncRNA.

scholarly journals Atg27 Is Required for Autophagy-dependent Cycling of Atg9

2007 ◽  
Vol 18 (2) ◽  
pp. 581-593 ◽  
Author(s):  
Wei-Lien Yen ◽  
Julie E. Legakis ◽  
Usha Nair ◽  
Daniel J. Klionsky
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Golgi Complex ◽  
Transmembrane Protein ◽  
Eukaryotic Cells ◽  
Vesicle Formation ◽  
Catabolic Pathway ◽  
Autophagosome Formation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Double Membrane ◽  
Selective Autophagy

Autophagy is a catabolic pathway for the degradation of cytosolic proteins or organelles and is conserved among all eukaryotic cells. The hallmark of autophagy is the formation of double-membrane cytosolic vesicles, termed autophagosomes, which sequester cytoplasm; however, the mechanism of vesicle formation and the membrane source remain unclear. In the yeast Saccharomyces cerevisiae, selective autophagy mediates the delivery of specific cargos to the vacuole, the analog of the mammalian lysosome. The transmembrane protein Atg9 cycles between the mitochondria and the pre-autophagosomal structure, which is the site of autophagosome biogenesis. Atg9 is thought to mediate the delivery of membrane to the forming autophagosome. Here, we characterize a second transmembrane protein Atg27 that is required for specific autophagy in yeast. Atg27 is required for Atg9 cycling and shuttles between the pre-autophagosomal structure, mitochondria, and the Golgi complex. These data support a hypothesis that multiple membrane sources supply the lipids needed for autophagosome formation.

Dynamics of autophagosome formation: a pulse and a sequence of waves

2014 ◽  
Vol 42 (5) ◽  
pp. 1389-1395 ◽  
Author(s):  
Nicholas T. Ktistakis ◽  
Eleftherios Karanasios ◽  
Maria Manifava
Keyword(s):  
Mammalian Cells ◽  
De Novo ◽  
Stress Conditions ◽  
Present Review ◽  
Eukaryotic Cells ◽  
Current View ◽  
Protein Assemblies ◽  
Autophagosome Formation ◽  
Flat Membrane ◽  
A Current

Autophagosomes form in eukaryotic cells in response to starvation or to other stress conditions brought about by the unwanted presence in the cytosol of pathogens, damaged organelles or aggregated protein assemblies. The uniqueness of autophagosomes is that they form de novo and that they are the only double-membraned vesicles known in cells, having arisen from flat membrane sheets which have expanded and self-closed. The various steps describing their formation as well as most of the protein and lipid components involved have been identified. Furthermore, the hierarchical relationships among the components are well documented, and the mechanistic rationale for some of these hierarchies has been revealed. In the present review, we try to provide a current view of the process of autophagosome formation in mammalian cells, emphasizing along the way gaps in our knowledge that need additional work.

scholarly journals Redistribution of a glucuronoxylomannan epitope towards the capsule surface coincides with Titanisation in the human fungal pathogenCryptococcus neoformans

2018 ◽  
Author(s):  
Mark Probert ◽  
Xin Zhou ◽  
Margaret Goodall ◽  
Simon A. Johnston ◽  
Ewa Bielska ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Therapeutic Potential ◽  
Cell Types ◽  
Fungal Species ◽  
Independent Manner ◽  
Successful Infection ◽  
Polysaccharide Capsule ◽  
Serotype B ◽  
Etiological Agents ◽  
Made In

AbstractDisseminated infections with the fungal speciesCryptococcus neoformansor, less frequently,C. gattii,are a leading cause of mortality in immunocompromised individuals. Central to the virulence of both species is an elaborate polysaccharide capsule that consists predominantly of glucuronoxylomannan (GXM). Due to its abundance, GXM is an ideal target for host antibodies, and several monoclonal antibodies (mAbs) have previously been derived using purified GXM or whole capsular preparations as antigen. In addition to their application in the diagnosis of cryptococcosis, anti-GXM mAbs are invaluable tools for studying capsule structure. In this study, we report the production and characterisation of a novel anti-GXM mAb, Crp127, that unexpectedly reveals a role for GXM remodelling during the process of fungal Titanisation. We show that Crp127 recognises a GXM epitope in anO-acetylation dependent, but xylosylation-independent, manner. The epitope is differentially expressed by the four main serotypes ofCryptococcus neoformansandgattii,is heterogeneously expressed within clonal populations ofC. gattiiserotype B strains and is typically confined to the central region of the enlarged capsule. Uniquely, however, this epitope redistributes to the capsular surface in Titan cells, a recently recognised subset of giant fungal cells that are produced in the host lung and are critical for successful infection. Crp127 therefore highlights hitherto unexpected features of cryptococcal morphological change and may hold significant therapeutic potential in differentially identifying cryptococcal strains and subtypes.ImportanceCryptococcus neoformansandCryptococcus gattiiare the etiological agents of cryptococcosis, an invasive fungal infection responsible for approximately 200,000 deaths each year and 15% of AIDS-related deaths annually. Whilst the main virulence factor for both species is a highly variable polysaccharide capsule, formation of Titan cells also underlies the pathogenesis ofC. neoformans.Previous studies have shown that capsule composition differs between yeast and Titan cells, however no clear distinctions in the expression or localisation of specific capsular epitopes have been made. In this study, we characterise a novel monoclonal antibody (mAb) specific to a capsular epitope that is differentially distributed throughout the capsules produced by yeast and Titan cells. Whilst this epitope is found within the midzone of yeast capsules, the presentation of this epitope on the surface of Titan cell capsules may represent a way in which these cell types are perceived differently by the immune system.

scholarly journals Extracellular Vesicle-Mediated RNA Release in Histoplasma capsulatum

mSphere ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Lysangela R. Alves ◽  
Roberta Peres da Silva ◽  
David A. Sanchez ◽  
Daniel Zamith-Miranda ◽  
Marcio L. Rodrigues ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Stress Responses ◽  
Histoplasma Capsulatum ◽  
Pathogenic Fungi ◽  
Extracellular Vesicle ◽  
Fungal Species ◽  
Cellular Communication ◽  
Content Type ◽  
Rna Molecules ◽  
Rna Content

ABSTRACT Eukaryotic cells, including fungi, release extracellular vesicles (EVs). These lipid bilayered compartments play essential roles in cellular communication and pathogenesis. EV composition is complex and includes proteins, glycans, pigments, and RNA. RNAs with putative roles in pathogenesis have been described in EVs produced by fungi. Here we describe the RNA content in EVs produced by the G186AR and G217B strains of Histoplasma capsulatum, an important human-pathogenic fungal pathogen. A total of 124 mRNAs were identified in both strains. In this set of RNA classes, 93 transcripts were enriched in EVs from the G217B strain, whereas 31 were enriched in EVs produced by the G186AR strain. This result suggests that there are important strain-specific properties in the mRNA composition of fungal EVs. We also identified short fragments (25 to 40 nucleotides in length) that were strain specific, with a greater number identified in EVs produced by the G217B strain. Remarkably, the most highly enriched processes were stress responses and translation. Half of these fragments aligned to the reverse strand of the transcript, suggesting the occurrence of microRNA (miRNA)-like molecules in fungal EVs. We also compared the transcriptome profiles of H. capsulatum with the RNA composition of EVs, and no correlation was observed. Taking the results together, our study provided information about the RNA molecules present in H. capsulatum EVs and about the differences in composition between the strains. In addition, we found no correlation between the most highly expressed transcripts in the cell and their presence in the EVs, reinforcing the idea that the RNAs were directed to the EVs by a regulated mechanism. IMPORTANCE Extracellular vesicles (EVs) play important roles in cellular communication and pathogenesis. The RNA molecules in EVs have been implicated in a variety of processes. EV-associated RNA classes have recently been described in pathogenic fungi; however, only a few reports of studies describing the RNAs in fungal EVs are available. Improved knowledge of EV-associated RNA will contribute to the understanding of their role during infection. In this study, we described the RNA content in EVs produced by two isolates of Histoplasma capsulatum. Our results add this important pathogen to the current short list of fungal species with the ability to use EVs for the extracellular release of RNA.

scholarly journals 68P Deciphering the interplay between nuclear RNA export factors and long non-coding RNAs in breast cancer metabolism

2020 ◽  
Vol 31 ◽  
pp. S38
Author(s):  
C. Klec ◽  
D. Schwarzenbacher ◽  
B. Gottschalk ◽  
R. Margit ◽  
F. Prinz ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Metabolism ◽  
Nuclear Rna ◽  
Rna Export ◽  
Non Coding Rnas ◽  
Nuclear Rna Export ◽  
Rna Export Factors

scholarly journals Unveiling Protein Kinase A Targets in Cryptococcus neoformans Capsule Formation

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
J. Andrew Alspaugh
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Cryptococcus Neoformans ◽  
Signal Transduction Pathway ◽  
Fungal Species ◽  
Protein Accumulation ◽  
Fungal Cell ◽  
Ubiquitin Proteasome ◽  
Proteasome Regulation ◽  
Kinase A

ABSTRACT The protein kinase A (PKA) signal transduction pathway has been associated with pathogenesis in many fungal species. Geddes and colleagues [mBio 7(1):e01862-15, 2016, doi:10.1128/mBio.01862-15] used quantitative proteomics approaches to define proteins with altered abundance during protein kinase A (PKA) activation and repression in the opportunistic human fungal pathogen Cryptococcus neoformans . They observed an association between microbial PKA signaling and ubiquitin-proteasome regulation of protein homeostasis. Additionally, they correlated these processes with expression of polysaccharide capsule on the fungal cell surface, the main virulence-associated phenotype in this organism. Not only are their findings important for microbial pathogenesis, but they also support similar associations between human PKA signaling and ubiquitinated protein accumulation in neurodegenerative diseases.

FEASIBILITY OF THE NON-CODING RNA GRADIENTS IN CELLS

2009 ◽  
Vol 04 (03) ◽  
pp. 267-272 ◽  
Author(s):  
VLADIMIR P. ZHDANOV
Keyword(s):  
Kinetic Model ◽  
Gene Transcription ◽  
Eukaryotic Cells ◽  
Model Parameters ◽  
Protein Association ◽  
Non Coding Rna ◽  
A Cell ◽  
Non Coding Rnas ◽  
Spatio Temporal

In eukaryotic cells, the gene transcription often results in the formation of non-coding RNAs (ncRNAs). The key function of such RNAs is to bind to and modulate the activity of mRNAs and/or proteins. To scrutinize this ncRNA function in a cell, the author (i) proposes a spatio-temporal kinetic model, including ncRNA–protein association and degradation, (ii) derives a criterion of feasibility of the ncRNA gradients, and (iii) shows that this criterion can be satisfied with physically reasonable values of the model parameters. Thus, the ncRNA gradients are feasible. For the ncRNA–mRNA association and degradation, the situation is similar. The likely biological role of such gradients is open for debate.

scholarly journals Troponoids Can Inhibit Growth of the Human Fungal Pathogen Cryptococcus neoformans

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Maureen J. Donlin ◽  
Anthony Zunica ◽  
Ashlyn Lipnicky ◽  
Aswin K. Garimallaprabhakaran ◽  
Alex J. Berkowitz ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Fungal Pathogen ◽  
Antimicrobial Activities ◽  
Fungal Species ◽  
Content Type ◽  
Human Fungal Pathogen ◽  
Red Cedar ◽  
Immunosuppressed Patients ◽  
Western Red Cedar

ABSTRACT Cryptococcus neoformans is a pathogen that is common in immunosuppressed patients. It can be treated with amphotericin B and fluconazole, but the mortality rate remains 15 to 30%. Thus, novel and more effective anticryptococcal therapies are needed. The troponoids are based on natural products isolated from western red cedar, and have a broad range of antimicrobial activities. Extracts of western red cedar inhibit the growth of several fungal species, but neither western red cedar extracts nor troponoid derivatives have been tested against C. neoformans. We screened 56 troponoids for their ability to inhibit C. neoformans growth and to assess whether they may be attractive candidates for development into anticryptococcal drugs. We determined MICs at which the compounds inhibited 80% of cryptococcal growth relative to vehicle-treated controls and identified 12 compounds with MICs ranging from 0.2 to 15 μM. We screened compounds with MICs of ≤20 μM for cytotoxicity in liver hepatoma cells. Fifty percent cytotoxicity values (CC50s) ranged from 4 to >100 μM. The therapeutic indexes (TI, CC50/MIC) for most of the troponoids were fairly low, with most being <8. However, two compounds had TI values that were >8, including a tropone with a TI of >300. These tropones are fungicidal and are not antagonistic when used in combination with fluconazole or amphotericin B. Inhibition by these two tropones remains unchanged under conditions favoring cryptococcal capsule formation. These data support the hypothesis that troponoids may be a productive scaffold for the development of novel anticryptococcal therapies.

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