Publications by authors named "Susanne Pfeiffer"

11 Publications

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Evolutionary and functional analyses demonstrate conserved ferroptosis protection by Arabidopsis GPXs in mammalian cells.

FASEB J 2021 Jun;35(6):e21550

Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou, China.

Species have evolved unique mechanisms to combat the effects of oxidative stress inside cells. A particularly devastating consequence of an unhindered oxidation of membrane lipids in the presence of iron results in cell death, known as ferroptosis. Hallmarks of ferroptosis, including peroxidation of polyunsaturated fatty acids, are conserved among animals and plants, however, early divergence of an ancestral mammalian GPX4 (mGPX4) has complicated our understanding of mechanistic similarities between species. To this end, we performed a comprehensive phylogenetic analysis and identified that orthologous Arabidopsis GPXs (AtGPXs) are more highly related to mGPX4 than mGPX4 is to other mammalian GPXs. This high degree of conservation suggested that experimental substitution may be possible. We, therefore, ectopically expressed AtGPX1-8 in ferroptosis-sensitive mouse fibroblasts. This substitution experiment revealed highest protection against ferroptosis induction by AtGPX5, as well as moderate protection by AtGPX2, -7, and -8. Further analysis of these cells revealed substantial abatement of lipid peroxidation in response to pharmacological challenge. The results suggest that the presence of ancestral GPX4 resulted in later functional divergence and specialization of GPXs in plants. The results also challenge a strict requirement for selenocysteine activity and suggest thioredoxin as a potent parallel antioxidant system in both plants and mammals.
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http://dx.doi.org/10.1096/fj.202000856RDOI Listing
June 2021

Nonsense-mediated decay factor SMG7 sensitizes cells to TNFα-induced apoptosis via CYLD tumor suppressor and the noncoding oncogene Pvt1.

Mol Oncol 2020 10 13;14(10):2420-2435. Epub 2020 Jul 13.

Genetics and Cellular Engineering Group, Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Munich GmbH, German Research Center for Environmental Health, Neuherberg, Germany.

Nonsense-mediated decay (NMD) proteins are responsible for the surveillance and degradation of aberrant RNAs. Suppressor with morphogenetic effect on genitalia 7 (SMG7) is an NMD complex protein and a regulator of tumor necrosis factor (TNF)-induced extrinsic apoptosis; however, this unique function has not been explored in detail. In this study, we show that loss of Smg7 leads to unrestricted expression of long noncoding RNAs (lncRNAs) in addition to NMD targets. Functional analysis of Smg7 cells showed downregulation of the tumor suppressor cylindromatosis (CYLD) and diminished caspase activity, thereby switching cells to nuclear factor-κB (NF-κB)-mediated protection. This positive relationship between SMG7 and CYLD was found to be widely conserved in human cancer cell lines and renal carcinoma samples from The Cancer Genome Atlas. In addition to CYLD suppression, upregulation of lncRNAs Pvt1 and Adapt33 rendered cells resistant to TNF, while pharmacologic inhibition of NF-κB in Pvt1-overexpressing TNF-resistant cells and Smg7-deficient spheroids re-established TNF-induced lethality. Thus, loss of SMG7 decouples regulation of two separate oncogenic factors with cumulative downstream effects on the NF-κB pathway. The data highlight a novel and specific regulation of oncogenic factors by SMG7 and pinpoint a composite tumor suppressor role in response to TNF.
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http://dx.doi.org/10.1002/1878-0261.12754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7530794PMC
October 2020

The effects of seasonal climate variability on dengue annual incidence in Hong Kong: A modelling study.

Sci Rep 2020 03 9;10(1):4297. Epub 2020 Mar 9.

Centre for Applied One Health Research and Policy Advice, City University of Hong Kong, Hong Kong, China.

In recent years, dengue has been rapidly spreading and growing in the tropics and subtropics. Located in southern China, Hong Kong's subtropical monsoon climate may favour dengue vector populations and increase the chance of disease transmissions during the rainy summer season. An increase in local dengue incidence has been observed in Hong Kong ever since the first case in 2002, with an outbreak reaching historically high case numbers in 2018. However, the effects of seasonal climate variability on recent outbreaks are unknown. As the local cases were found to be spatially clustered, we developed a Poisson generalized linear mixed model using pre-summer monthly total rainfall and mean temperature to predict annual dengue incidence (the majority of local cases occur during or after the summer months), over the period 2002-2018 in three pre-defined areas of Hong Kong. Using leave-one-out cross-validation, 5 out of 6 observations of area-specific outbreaks during the major outbreak years 2002 and 2018 were able to be predicted. 42 out of a total of 51 observations (82.4%) were within the 95% confidence interval of the annual incidence predicted by our model. Our study found that the rainfall before and during the East Asian monsoon (pre-summer) rainy season is negatively correlated with the annual incidence in Hong Kong while the temperature is positively correlated. Hence, as mosquito control measures in Hong Kong are intensified mainly when heavy rainfalls occur during or close to summer, our study suggests that a lower-than-average intensity of pre-summer rainfall should also be taken into account as an indicator of increased dengue risk.
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http://dx.doi.org/10.1038/s41598-020-60309-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7062697PMC
March 2020

GTP Cyclohydrolase 1/Tetrahydrobiopterin Counteract Ferroptosis through Lipid Remodeling.

ACS Cent Sci 2020 Jan 27;6(1):41-53. Epub 2019 Dec 27.

Institute of Molecular Toxicology and Pharmacology, Genetics and Cellular Engineering Group, HelmholtzZentrum Muenchen, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany.

Ferroptosis is an iron-dependent form of regulated cell death linking iron, lipid, and glutathione levels to degenerative processes and tumor suppression. By performing a genome-wide activation screen, we identified a cohort of genes antagonizing ferroptotic cell death, including GTP cyclohydrolase-1 (GCH1) and its metabolic derivatives tetrahydrobiopterin/dihydrobiopterin (BH/BH). Synthesis of BH/BH by GCH1-expressing cells caused lipid remodeling, suppressing ferroptosis by selectively preventing depletion of phospholipids with two polyunsaturated fatty acyl tails. GCH1 expression level in cancer cell lines stratified susceptibility to ferroptosis, in accordance with its expression in human tumor samples. The GCH1-BH-phospholipid axis acts as a master regulator of ferroptosis resistance, controlling endogenous production of the antioxidant BH, abundance of CoQ, and peroxidation of unusual phospholipids with two polyunsaturated fatty acyl tails. This demonstrates a unique mechanism of ferroptosis protection that is independent of the GPX4/glutathione system.
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http://dx.doi.org/10.1021/acscentsci.9b01063DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978838PMC
January 2020

ENCoRE: an efficient software for CRISPR screens identifies new players in extrinsic apoptosis.

BMC Genomics 2017 Nov 25;18(1):905. Epub 2017 Nov 25.

Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum Munich, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.

Background: As CRISPR/Cas9 mediated screens with pooled guide libraries in somatic cells become increasingly established, an unmet need for rapid and accurate companion informatics tools has emerged. We have developed a lightweight and efficient software to easily manipulate large raw next generation sequencing datasets derived from such screens into informative relational context with graphical support. The advantages of the software entitled ENCoRE (Easy NGS-to-Gene CRISPR REsults) include a simple graphical workflow, platform independence, local and fast multithreaded processing, data pre-processing and gene mapping with custom library import.

Results: We demonstrate the capabilities of ENCoRE to interrogate results from a pooled CRISPR cellular viability screen following Tumor Necrosis Factor-alpha challenge. The results not only identified stereotypical players in extrinsic apoptotic signaling but two as yet uncharacterized members of the extrinsic apoptotic cascade, Smg7 and Ces2a. We further validated and characterized cell lines containing mutations in these genes against a panel of cell death stimuli and involvement in p53 signaling.

Conclusions: In summary, this software enables bench scientists with sensitive data or without access to informatic cores to rapidly interpret results from large scale experiments resulting from pooled CRISPR/Cas9 library screens.
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http://dx.doi.org/10.1186/s12864-017-4285-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5702081PMC
November 2017

Microdialysis Sampling from Wound Fluids Enables Quantitative Assessment of Cytokines, Proteins, and Metabolites Reveals Bone Defect-Specific Molecular Profiles.

PLoS One 2016 21;11(7):e0159580. Epub 2016 Jul 21.

University Center of Orthopedics and Trauma Surgery and Center for Translational Bone, Joint and Soft Tissue Research, University Hospital "Carl Gustav Carus", TU Dresden, Dresden, Germany.

Bone healing involves a variety of different cell types and biological processes. Although certain key molecules have been identified, the molecular interactions of the healing progress are not completely understood. Moreover, a clinical routine for predicting the quality of bone healing after a fracture in an early phase is missing. This is mainly due to a lack of techniques to comprehensively screen for cytokines, growth factors and metabolites at their local site of action. Since all soluble molecules of interest are present in the fracture hematoma, its in-depth assessment could reveal potential markers for the monitoring of bone healing. Here, we describe an approach for sampling and quantification of cytokines and metabolites by using microdialysis, combined with solid phase extractions of proteins from wound fluids. By using a control group with an isolated soft tissue wound, we could reveal several bone defect-specific molecular features. In bone defect dialysates the neutrophil chemoattractants CXCL1, CXCL2 and CXCL3 were quantified with either a higher or earlier response compared to dialysate from soft tissue wound. Moreover, by analyzing downstream adaptions of the cells on protein level and focusing on early immune response, several proteins involved in the immune cell migration and activity could be identified to be specific for the bone defect group, e.g. immune modulators, proteases and their corresponding inhibitors. Additionally, the metabolite screening revealed different profiles between the bone defect group and the control group. In summary, we identified potential biomarkers to indicate imbalanced healing progress on all levels of analysis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159580PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956113PMC
July 2017

Hypoxia-inducible factor 3A gene expression and methylation in adipose tissue is related to adipose tissue dysfunction.

Sci Rep 2016 06 27;6:27969. Epub 2016 Jun 27.

Leipzig University Medical Center, IFB AdiposityDiseases, University of Leipzig, Leipzig, Germany.

Recently, a genome-wide analysis identified DNA methylation of the HIF3A (hypoxia-inducible factor 3A) as strongest correlate of BMI. Here we tested the hypothesis that HIF3A mRNA expression and CpG-sites methylation in adipose tissue (AT) and genetic variants in HIF3A are related to parameters of AT distribution and function. In paired samples of subcutaneous AT (SAT) and visceral AT (VAT) from 603 individuals, we measured HIF3A mRNA expression and analyzed its correlation with obesity and related traits. In subgroups of individuals, we investigated the effects on HIF3A genetic variants on its AT expression (N = 603) and methylation of CpG-sites (N = 87). HIF3A expression was significantly higher in SAT compared to VAT and correlated with obesity and parameters of AT dysfunction (including CRP and leucocytes count). HIF3A methylation at cg22891070 was significantly higher in VAT compared to SAT and correlated with BMI, abdominal SAT and VAT area. Rs8102595 showed a nominal significant association with AT HIF3A methylation levels as well as with obesity and fat distribution. HIF3A expression and methylation in AT are fat depot specific, related to obesity and AT dysfunction. Our data support the hypothesis that HIF pathways may play an important role in the development of AT dysfunction in obesity.
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http://dx.doi.org/10.1038/srep27969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4921806PMC
June 2016

Novel pathomechanisms of cardiomyocyte dysfunction in a model of heart failure with preserved ejection fraction.

Eur J Heart Fail 2016 08 2;18(8):987-97. Epub 2016 May 2.

Department of Cardiology, Charité University Medicine Berlin, Campus Virchow-Klinikum, Berlin, Germany.

Aims: Heart failure with preserved ejection fraction (HFpEF) is increasingly common, but the underlying cellular mechanisms are not well understood. We investigated cardiomyocyte function and the role of SEA0400, an Na(+) /Ca(2+) exchanger (NCX) inhibitor in a rat model of chronic kidney disease (CKD) with HFpEF.

Methods And Results: Male Wistar rats were subjected to subtotal nephrectomy (NXT) or sham operation (Sham). After 8 and 24 weeks, in vivo (haemodynamics, echocardiography) and in vitro function (LV cardiomyocyte cell shortening (CS), and Ca(2+) transients (CaT)) were determined without and with SEA0400. In a subgroup of rats, SEA0400 or vehicle was given p.o. (1 mg/kg b.w.) between week 8 and 24. NXT resulted in stable compensated CKD and HFpEF [hypertrophied left ventricle, prolonged LV isovolumetric relaxation constant TAU (IVRc TAU), elevated end diastolic pressure (EDP), increased lung weight (pulmonary congestion), and preserved LV systolic function (EF, dP/dt)]. In NXT cardiomyocytes, the amplitude of CS and CaT were unchanged but relaxation and CaT decay were progressively prolonged at 8 and 24 weeks vs. Sham, individually correlating with diastolic dysfunction in vivo. NCX forward mode activity (caffeine response) was progressively reduced, while NCX protein expression was up-regulated, suggesting increased NCX reverse mode activity in NXT. SEA0400 acutely improved relaxation in NXT in vivo and in cardiomyocytes and improved cardiac remodelling and diastolic function when given chronically.

Conclusions: This model of renal HFpEF is associated with slowed relaxation of LV cardiomyocytes. Treatment with SEA0400 improved cardiomyocyte function, remodelling, and HFpEF.
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http://dx.doi.org/10.1002/ejhf.524DOI Listing
August 2016

Predictors of work-related sensitisation, allergic rhinitis and asthma in early work life.

Eur Respir J 2014 Sep 25;44(3):657-65. Epub 2014 Jun 25.

Occupational and Environmental Epidemiology and Net Teaching Unit, Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, University Hospital of Munich (LMU), Munich, Germany.

Although work-related asthma and allergies are a huge burden for society, investigation of occupational exposures in early work life using an unexposed reference group is rare. Thus, the present analyses aimed to assess the potential impact of occupational exposure and other risk factors on the prevalence of work-related sensitisation and incidence of allergic rhinitis/asthma using a population-based approach and taking into account an unexposed reference group. In SOLAR (Study on Occupational Allergy Risks) II, German participants of ISAAC (International Study of Asthma and Allergies in Childhood) phase II were followed from childhood (9-11 years) until early adulthood (19-24 years). Data on 1570 participants were available to fit predictive models. Occupational exposure was not statistically significantly associated with disease prevalence/incidence. Sensitisation in childhood, parental asthma, environmental tobacco smoke exposure during puberty, sex and study location were statistically significant predictors of outcome. Our results indicate that occupational exposure is of little relevance for work-related sensitisation prevalence and allergic rhinitis/asthma incidence in early work life, while other risk factors can be used to improve career guidance for adolescents. Further research on the role of a potential healthy hire effect and the impact of longer exposure duration is needed.
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http://dx.doi.org/10.1183/09031936.00153013DOI Listing
September 2014

Direct cloning of isogenic murine DNA in yeast and relevance of isogenicity for targeting in embryonic stem cells.

PLoS One 2013 13;8(9):e74207. Epub 2013 Sep 13.

Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.

Efficient gene targeting in embryonic stem cells requires that modifying DNA sequences are identical to those in the targeted chromosomal locus. Yet, there is a paucity of isogenic genomic clones for human cell lines and PCR amplification cannot be used in many mutation-sensitive applications. Here, we describe a novel method for the direct cloning of genomic DNA into a targeting vector, pRTVIR, using oligonucleotide-directed homologous recombination in yeast. We demonstrate the applicability of the method by constructing functional targeting vectors for mammalian genes Uhrf1 and Gfap. Whereas the isogenic targeting of the gene Uhrf1 showed a substantial increase in targeting efficiency compared to non-isogenic DNA in mouse E14 cells, E14-derived DNA performed better than the isogenic DNA in JM8 cells for both Uhrf1 and Gfap. Analysis of 70 C57BL/6-derived targeting vectors electroporated in JM8 and E14 cell lines in parallel showed a clear dependence on isogenicity for targeting, but for three genes isogenic DNA was found to be inhibitory. In summary, this study provides a straightforward methodological approach for the direct generation of isogenic gene targeting vectors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0074207PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3772885PMC
June 2014

[Anorexia nervosa in childhood and adolescence. Nursing in inpatient psychosomatic treatment].

Authors:
Susanne Pfeiffer

Kinderkrankenschwester 2008 Jul;27(7):291-4

Gesundheits- und Kinderkrankenpflegerin Psychosomatische Abteilung Clementine Kinderhospital, Frankfurt.

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July 2008