scholarly journals Destabilization of chromosome structure by histone H3 lysine 27 methylation

2018 ◽  
Author(s):  
Mareike Möller ◽  
Klaas Schotanus ◽  
Jessica Soyer ◽  
Janine Haueisen ◽  
Kathrin Happ ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Normal Cell ◽  
Genome Stability ◽  
Large Scale ◽  
Chromosome Structure ◽  
Cell Function ◽  
Pathogenic Fungus ◽  
The Impact ◽  
Accessory Chromosomes

AbstractChromosome and genome stability are important for normal cell function as instability often correlates with disease and dysfunction of DNA repair mechanisms. Many organisms maintain supernumerary or accessory chromosomes that deviate from standard chromosomes. The pathogenic fungus Zymoseptoria tritici has as many as eight accessory chromosomes, which are highly unstable during meiosis and mitosis, transcriptionally repressed, show enrichment of repetitive elements, and enrichment with heterochromatic histone methylation marks, e.g., trimethylation of H3 lysine 9 or lysine 27 (H3K9me3, H3K27me3). To elucidate the role of heterochromatin on genome stability in Z. tritici, we deleted the genes encoding the methyltransferases responsible for H3K9me3 and H3K27me3, kmt1 and kmt6, respectively, and generated a double mutant. We combined experimental evolution and genomic analyses to determine the impact of these deletions on chromosome and genome stability, both in vitro and in planta. We used whole genome sequencing, ChIP-seq, and RNA-seq to compare changes in genome and chromatin structure, and differences in gene expression between mutant and wildtype strains. Analyses of genome and ChIP-seq data in H3K9me3-deficient strains revealed dramatic chromatin reorganization, where H3K27me3 is mostly relocalized into regions that are enriched with H3K9me3 in wild type. Many genome rearrangements and formation of new chromosomes were found in the absence of H3K9me3, accompanied by activation of transposable elements. In stark contrast, loss of H3K27me3 actually increased the stability of accessory chromosomes under normal growth conditions in vitro, even without large scale changes in gene activity. We conclude that H3K9me3 is important for the maintenance of genome stability because it disallows H3K27me3 in these regions. In this system, H3K27me3 reduces the overall stability of accessory chromosomes, generating a “metastable” state for these quasi-essential regions of the genome.Author SummaryGenome and chromosome stability are essential to maintain normal cell function and viability. However, differences in genome and chromosome structure are frequently found in organisms that undergo rapid adaptation to changing environmental conditions, and in humans are often found in cancer cells. We study genome instability in a fungal pathogen that exhibits a high degree of genetic diversity. Regions that show extraordinary diversity in this pathogen are the transposon-rich accessory chromosomes, which contain few genes that are of unknown benefit to the organism but maintained in the population and thus considered “quasi essential”. Accessory chromosomes in all fungi studied so far are enriched with markers for heterochromatin, namely trimethylation of H3 lysine 9 and 27 (H3K9me3, H3K27me3). We show that loss of these heterochromatin marks has strong but opposing effects on genome stability. While loss of the transposon-associated mark H3K9me3 destabilizes the entire genome, presence of H3K27me3 favors instability of accessory chromosomes. Our study provides insight into the relationship between chromatin and genome stability and why some regions are more susceptible to genetic diversity than others.

scholarly journals Microfluidic deep mutational scanning of the human executioner caspases reveals differences in structure and regulation

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Hridindu Roychowdury ◽  
Philip A. Romero
Keyword(s):  
Large Scale ◽  
Cysteine Proteases ◽  
Amino Acid Substitutions ◽  
Substrate Preferences ◽  
Functional Differences ◽  
Caspase Family ◽  
Executioner Caspases ◽  
The Impact ◽  
Human Caspase

AbstractThe human caspase family comprises 12 cysteine proteases that are centrally involved in cell death and inflammation responses. The members of this family have conserved sequences and structures, highly similar enzymatic activities and substrate preferences, and overlapping physiological roles. In this paper, we present a deep mutational scan of the executioner caspases CASP3 and CASP7 to dissect differences in their structure, function, and regulation. Our approach leverages high-throughput microfluidic screening to analyze hundreds of thousands of caspase variants in tightly controlled in vitro reactions. The resulting data provides a large-scale and unbiased view of the impact of amino acid substitutions on the proteolytic activity of CASP3 and CASP7. We use this data to pinpoint key functional differences between CASP3 and CASP7, including a secondary internal cleavage site, CASP7 Q196 that is not present in CASP3. Our results will open avenues for inquiry in caspase function and regulation that could potentially inform the development of future caspase-specific therapeutics.

scholarly journals Exposure to airborne gold nanoparticles: a review of current toxicological data on the respiratory tract

2020 ◽  
Vol 22 (8) ◽  
Author(s):  
Barbara De Berardis ◽  
Magda Marchetti ◽  
Anna Risuglia ◽  
Federica Ietto ◽  
Carla Fanizza ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Human Health ◽  
Large Scale ◽  
Current Knowledge ◽  
Engineered Nanoparticles ◽  
In Vivo Studies ◽  
Field Exposure ◽  
The Impact

AbstractIn recent years, the introduction of innovative low-cost and large-scale processes for the synthesis of engineered nanoparticles with at least one dimension less than 100 nm has led to countless useful and extensive applications. In this context, gold nanoparticles stimulated a growing interest, due to their peculiar characteristics such as ease of synthesis, chemical stability and optical properties. This stirred the development of numerous applications especially in the biomedical field. Exposure of manufacturers and consumers to industrial products containing nanoparticles poses a potential risk to human health and the environment. Despite this, the precise mechanisms of nanomaterial toxicity have not yet been fully elucidated. It is well known that the three main routes of exposure to nanomaterials are by inhalation, ingestion and through the skin, with inhalation being the most common route of exposure to NPs in the workplace. To provide a complete picture of the impact of inhaled gold nanoparticles on human health, in this article, we review the current knowledge about the physico-chemical characteristics of this nanomaterial, in the size range of 1–100 nm, and its toxicity for pulmonary structures both in vitro and in vivo. Studies comparing the toxic effect of NPs larger than 100 nm (up to 250 nm) are also discussed.

scholarly journals Helicases FANCJ, RTEL1 and BLM Act on Guanine Quadruplex DNA in Vivo

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 870 ◽  
Author(s):  
Peter Lansdorp ◽  
Niek van Wietmarschen
Keyword(s):  
Gene Expression ◽  
Genome Stability ◽  
Cell Function ◽  
Historical Context ◽  
Telomere Maintenance ◽  
Dna Structures ◽  
G4 Dna ◽  
Guanine Quadruplex

Guanine quadruplex (G4) structures are among the most stable secondary DNA structures that can form in vitro, and evidence for their existence in vivo has been steadily accumulating. Originally described mainly for their deleterious effects on genome stability, more recent research has focused on (potential) functions of G4 structures in telomere maintenance, gene expression, and other cellular processes. The combined research on G4 structures has revealed that properly regulating G4 DNA structures in cells is important to prevent genome instability and disruption of normal cell function. In this short review we provide some background and historical context of our work resulting in the identification of FANCJ, RTEL1 and BLM as helicases that act on G4 structures in vivo. Taken together these studies highlight important roles of different G4 DNA structures and specific G4 helicases at selected genomic locations and telomeres in regulating gene expression and maintaining genome stability.

scholarly journals IMMU-46. EXAMINATION OF THE EFFECTS OF DEXAMETHASONE ON THE EFFICACY OF IMMUNOTHERAPY IN GLIOMA USING GENE-MEDIATED CYTOTOXIC IMMUNOTHERAPY

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi129-vi129
Author(s):  
Marilin Koch ◽  
Mykola Zdioruk ◽  
M Oskar Nowicki ◽  
Estuardo Aguilar ◽  
Laura Aguilar ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Function ◽  
Immune Cell ◽  
Symptomatic Treatment ◽  
Tumor Cell Death ◽  
The Impact

Abstract RATIONALE Dexamethasone is frequently used in symptomatic treatment of glioma patients, although it is known to cause immune suppression. Checkpoint inhibitor immunotherapies have not yet been successful in glioma treatments. Gene-mediated cytotoxic immunotherapy (GMCI) is an immunotherapeutic approach that uses aglatimagene besadenovec with an anti-herpetic prodrug to induce immunogenic tumor cell death and immune cell attraction to the tumor site with potent CD8 T cell activation. GMCI is currently in clinical trials for solid tumors including glioblastoma, where it showed encouraging survival results in a Phase 2 study that did not limit the use of dexamethasone. However, the effects of dexamethasone on its efficacy have not been explored. METHODS We investigated the effects of dexamethasone on GMCI in vitro using cytotoxicity and T-cell-killing assays in glioblastoma cell lines. The impact of dexamethasone in vivo was assessed in an orthotopic syngeneic murine glioblastoma model. RESULTS Cyotoxicity assays showed that Dexamethasone has a slight impact on GMCI in vitro. In contrast, we observed a highly significant effect in T-cell-functional assays in which killing was greatly impaired. Immune cell response assays revealed a reduced T-cell proliferation after co-culture with supernatant from dexamethasone or combination treated glioblastoma cells in contrast to GMCI alone. In a murine model, the combination of GMCI and dexamethasone resulted in a significant reduction in median symptom-free survival (29d) in comparison to GMCI alone (39.5d) (P = 0.0184). CONCLUSION Our data suggest that high doses of dexamethasone may negatively impact the efficacy of immunotherapy for glioma, which may be a consequence of impaired T cell function. These results support the idea that there is a need in identifying possible alternatives to dexamethasone to maximize the effectiveness of immunostimulatory therapies such as GMCI.

scholarly journals Circulating miRNA 887 is differentially expressed in ARDS and modulates endothelial function

2020 ◽  
Vol 318 (6) ◽  
pp. L1261-L1269 ◽  
Author(s):  
Andrew J. Goodwin ◽  
Pengfei Li ◽  
Perry V. Halushka ◽  
James A. Cook ◽  
Aman S. Sumal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
In Silico Analysis ◽  
Leukocyte Migration ◽  
Differentially Expressed ◽  
Expression Of Genes ◽  
Cell Gene Expression ◽  
And Function ◽  
The Impact

Circulating microRNAs (miRNAs) can be taken up by recipient cells and have been recently associated with the acute respiratory distress syndrome (ARDS). Their role in host predisposition to the syndrome is unknown. The objective of the study was to identify circulating miRNAs associated with the development of sepsis-related ARDS and examine their impact on endothelial cell gene expression and function. We determined miRNA levels in plasma collected from subjects during the first 24 h of admission to a tertiary intensive care unit for sepsis. A miRNA that was differentially expressed between subjects who did and did not develop ARDS was identified and was transfected into human pulmonary microvascular endothelial cells (HPMECs). RNA sequencing, in silico analysis, cytokine expression, and leukocyte migration assays were used to determine the impact of this miRNA on gene expression and cell function. In two cohorts, circulating miR-887-3p levels were elevated in septic patients who developed ARDS compared with those who did not. Transfection of miR-887-3p into HPMECs altered gene expression, including the upregulation of several genes previously associated with ARDS (e.g., CXCL10, CCL5, CX3CL1, VCAM1, CASP1, IL1B, IFNB, and TLR2), and activation of cellular pathways relevant to the response to infection. Functionally, miR-887-3p increased the endothelial release of chemokines and facilitated trans-endothelial leukocyte migration. Circulating miR-887-3p is associated with ARDS in critically ill patients with sepsis. In vitro, miR-887-3p regulates the expression of genes relevant to ARDS and neutrophil tracking. This miRNA may contribute to ARDS pathogenesis and could represent a novel therapeutic target.

scholarly journals Cryptococcus gattii Infection Dampens Th1 and Th17 Responses by Attenuating Dendritic Cell Function and Pulmonary Chemokine Expression in the Immunocompetent Hosts

2014 ◽  
Vol 82 (9) ◽  
pp. 3880-3890 ◽  
Author(s):  
Pornpimon Angkasekwinai ◽  
Nuntarat Sringkarin ◽  
Oratai Supasorn ◽  
Madtika Fungkrajai ◽  
Yui-Hsi Wang ◽  
...  
Keyword(s):  
Immune Responses ◽  
Cell Function ◽  
Cryptococcus Gattii ◽  
Cell Immune Response ◽  
Content Type ◽  
Chemokine Expression ◽  
Immunocompromised Hosts ◽  
The Impact ◽  
Highly Virulent

ABSTRACTCryptococcal infections are primarily caused by two related fungal species:Cryptococcus neoformansandCryptococcus gattii. It is well known thatC. neoformansgenerally affects immunocompromised hosts; however,C. gattiiinfection can cause diseases in not only immunocompromised hosts but also immunocompetent individuals. While recent studies suggest thatC. gattiiinfection could dampen pulmonary neutrophil recruitment and inflammatory cytokine production in immunocompetent hosts, the impact ofC. gattiiinfection on the development of their adaptive T helper cell immune response has not been addressed. Here, we report thatC. neoformansinfection with highly virulent and less virulent strains preferentially induced pulmonary Th1 and Th17 immune responses in the host, respectively. However, fewer pulmonary Th1 and Th17 cells could be detected in mice infected withC. gattiistrains. Notably, dendritic cells (DC) in mice infected withC. gattiiexpressed much lower levels of surface MHC-II andIl12orIl23transcripts and failed to induce effective Th1 and Th17 differentiationin vitro. Furthermore, the expression levels ofIp10andCxcl9transcripts, encoding Th1-attracting chemokines, were significantly reduced in the lungs of mice infected with the highly virulentC. gattiistrain. Thus, our data suggest thatC. gattiiinfection dampens the DC-mediated effective Th1/Th17 immune responses and downregulates the pulmonary chemokine expression, thus resulting in the inability to mount protective immunity in immunocompetent hosts.

scholarly journals Within-patient genetic diversity of SARS-CoV-2

2020 ◽  
Author(s):  
Jack Kuipers ◽  
Aashil A Batavia ◽  
Kim Philipp Jablonski ◽  
Fritz Bayer ◽  
Nico Borgsmüller ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variants ◽  
Large Scale ◽  
Virus Genome ◽  
Spike Gene ◽  
Medical Interventions ◽  
Consensus Sequences ◽  
The Public ◽  
Number Of Patients ◽  
The Impact

AbstractSARS-CoV-2, the virus responsible for the current COVID-19 pandemic, is evolving into different genetic variants by accumulating mutations as it spreads globally. In addition to this diversity of consensus genomes across patients, RNA viruses can also display genetic diversity within individual hosts, and co-existing viral variants may affect disease progression and the success of medical interventions. To systematically examine the intra-patient genetic diversity of SARS-CoV-2, we processed a large cohort of 3939 publicly-available deeply sequenced genomes with specialised bioinformatics software, along with 749 recently sequenced samples from Switzerland. We found that the distribution of diversity across patients and across genomic loci is very unbalanced with a minority of hosts and positions accounting for much of the diversity. For example, the D614G variant in the Spike gene, which is present in the consensus sequences of 67.4% of patients, is also highly diverse within hosts, with 29.7% of the public cohort being affected by this coexistence and exhibiting different variants. We also investigated the impact of several technical and epidemiological parameters on genetic heterogeneity and found that age, which is known to be correlated with poor disease outcomes, is a significant predictor of viral genetic diversity.Author SummarySince it arose in late 2019, the new coronavirus (SARS-CoV-2) behind the COVID-19 pandemic has mutated and evolved during its global spread. Individual patients may host different versions, or variants, of the virus, hallmarked by different mutations. We examine the diversity of genetic variants coexisting within patients across a cohort of 3939 publicly accessible samples and 749 recently sequenced samples from Switzerland. We find that a small number of patients carry most of the diversity, and that patients with more diversity tend to be older. We also find that most of the diversity is concentrated in certain regions and positions of the virus genome. In particular, we find that a variant reported to increase infectivity is among the most diverse positions. Our study provides a large-scale survey of within-patient diversity of the SARS-CoV-2 genome.

scholarly journals Th17 Cell Enhances CD8 T-Cell Cytotoxicity via IL-21 Production in Emphysema Mice

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Min-Chao Duan ◽  
Ying Huang ◽  
Xiao-Ning Zhong ◽  
Hai-Juan Tang
Keyword(s):  
T Cells ◽  
T Cell ◽  
Inflammatory Response ◽  
Peripheral Blood ◽  
Th17 Cells ◽  
Cell Function ◽  
Cytotoxic T Cell ◽  
Protein Levels ◽  
The Impact

Emphysema is a T-cell mediated autoimmune disease caused predominantly by cigarette smoking. Th17 cells and related cytokines may contribute to this disorder. However, the possible implication of Th17 cells in regulating inflammatory response in emphysema remains to be elucidated. In the current study, we tested the protein levels of IL-17 and IL-21 in peripheral blood and lung tissues from cigarette-smoke- (CS-) exposed mice and air-exposed mice, analyzed the frequencies of CD4+IL-17+(Th17) cells, IL-21+Th17 cells, and CD8+IL-21R+T cells in peripheral blood and lung tissues of mice, and their relationship with emphysematous lesions, and explored the impact of IL-21 on cytotoxic CD8+T cells functionin vitro.It was found that the frequencies of Th17, IL-21+Th17, and CD8+IL-21R+T cells and the levels of IL-17 and IL-21 of CS-exposed mice were much higher than those of the air-exposed mice and correlated with emphysematous lesions. Additionally, the number of IL-21+Th17 cells positively correlated with the number of CD8+IL-21R+T cells. Thein vitroexperiments showed that IL-21 significantly augmented the secretion of perforin and granzyme B in CD8+T cells from CS-exposed mice. These data indirectly provide evidence that Th17 cells could be involved in the control of the local and system inflammatory response in emphysema by regulating CD8+cytotoxic T-cell function.

scholarly journals IAP inhibitors enhance co-stimulation to promote tumor immunity

2010 ◽  
Vol 207 (10) ◽  
pp. 2195-2206 ◽  
Author(s):  
Michael Dougan ◽  
Stephanie Dougan ◽  
Joanna Slisz ◽  
Brant Firestone ◽  
Matthew Vanneman ◽  
...  
Keyword(s):  
T Cell ◽  
Cytotoxic Activity ◽  
Small Molecule ◽  
Cell Function ◽  
Tumor Vaccine ◽  
Nuclear Factor Κb ◽  
Cell Responses ◽  
The Impact

The inhibitor of apoptosis proteins (IAPs) have recently been shown to modulate nuclear factor κB (NF-κB) signaling downstream of tumor necrosis factor (TNF) family receptors, positioning them as essential survival factors in several cancer cell lines, as indicated by the cytotoxic activity of several novel small molecule IAP antagonists. In addition to roles in cancer, increasing evidence suggests that IAPs have an important function in immunity; however, the impact of IAP antagonists on antitumor immune responses is unknown. In this study, we examine the consequences of IAP antagonism on T cell function in vitro and in the context of a tumor vaccine in vivo. We find that IAP antagonists can augment human and mouse T cell responses to physiologically relevant stimuli. The activity of IAP antagonists depends on the activation of NF-κB2 signaling, a mechanism paralleling that responsible for the cytotoxic activity in cancer cells. We further show that IAP antagonists can augment both prophylactic and therapeutic antitumor vaccines in vivo. These findings indicate an important role for the IAPs in regulating T cell–dependent responses and suggest that targeting IAPs using small molecule antagonists may be a strategy for developing novel immunomodulating therapies against cancer.

scholarly journals Acquired immune heterogeneity and its sources in human helminth infection

Parasitology ◽  
2010 ◽  
Vol 138 (2) ◽  
pp. 139-159 ◽  
Author(s):  
C. D. BOURKE ◽  
R. M. MAIZELS ◽  
F. MUTAPI
Keyword(s):  
Immune Responses ◽  
Large Scale ◽  
Antigen Expression ◽  
Epidemiological Studies ◽  
Public Health Importance ◽  
Host Immune Responses ◽  
Parasitic Worm ◽  
Acquired Immune Responses ◽  
The Impact

SUMMARYSimilarities in the immunobiology of different parasitic worm infections indicate that co-evolution of humans and helminths has shaped a common anti-helminth immune response. However, recentin vitroand immuno-epidemiological studies highlight fundamental differences and plasticity within host-helminth interactions. The ‘trade-off’ between immunity and immunopathology inherent in host immune responses occurs on a background of genetic polymorphism, variable exposure patterns and infection history. For the parasite, variation in life-cycle and antigen expression can influence the effector responses directed against them. This is particularly apparent when comparing gastrointestinal and tissue-dwelling helminths. Furthermore, insights into the impact of anti-helminthic treatment and co-infection on acquired immunity suggest that immune heterogeneity arises not from hosts and parasites in isolation, but also from the environment in which immune responses develop. Large-scale differences observed in the epidemiology of human helminthiases are a product of complex host-parasite-environment interactions which, given potential for exposure to parasite antigensin utero, can arise even before a parasite interacts with its human host. This review summarizes key differences identified in human acquired immune responses to nematode and trematode infections of public health importance and explores the factors contributing to these variations.

Sign in / Sign up

Export Citation Format

Share Document