Publications by authors named "Friederich E"

Whilst many lessons were learned from the COVID-19 pandemic, ongoing reflection is needed to develop and maintain preparedness for future outbreaks. Within the field of infectious disease and public health there remain silos and hierarchies in interdisciplinary work, with the risk that humanities and social sciences remain on the epistemological peripheries. However, these disciplines offer insights, expertise and tools that contribute to understanding responses to disease and uptake of interventions for prevention and treatment.

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There is evidence of genetic and neural system overlap in Autism Spectrum Disorder (ASD) and Early Psychosis (EP). Five datasets were pooled to compare mu suppression index (MSI), a proxy of mirror neuron activity, in EP, high functioning ASD, and healthy subjects (HS). ASDs and EPs with "active" negative symptoms showed significant differences in mu suppression, in response to Biological Motion/point-light display animation, compared to HS.

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At the request of the University of Luxembourg and following an external investigation, the Editor and Publisher have agreed to retract this paper owing to unreliable data.

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Focal adhesions are integrin-based structures that link the actin cytoskeleton and the extracellular matrix. They play an important role in various cellular functions such as cell signaling, cell motility and cell shape. To ensure and fine tune these different cellular functions, adhesions are regulated by a large number of proteins.

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Background: The majority of human cancer deaths are caused by metastasis. The metastatic dissemination is initiated by the breakdown of epithelial cell homeostasis. During this phenomenon, referred to as epithelial to mesenchymal transition (EMT), cells change their genetic and trancriptomic program leading to phenotypic and functional alterations.

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Endometrial carcinoma (EC) is the most frequent among infiltrating tumors of the female genital tract, with myometrial invasion representing an increase in the rate of recurrences and a decrease in survival. We have previously described ETV5 transcription factor associated with myometrial infiltration in human ECs. In this work, we further investigated ETV5 orchestrating downstream effects to confer the tumor the invasive capabilities needed to disseminate in the early stages of EC dissemination.

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Background: To understand biological processes and diseases, it is crucial to unravel the concerted interplay of transcription factors (TFs), microRNAs (miRNAs) and their targets within regulatory networks and fundamental sub-networks. An integrative computational resource generating a comprehensive view of these regulatory molecular interactions at a genome-wide scale would be of great interest to biologists, but is not available to date.

Results: To identify and analyze molecular interaction networks, we developed MIR@NT@N, an integrative approach based on a meta-regulation network model and a large-scale database.

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Epithelial to mesenchymal transition (EMT) is a key step toward metastasis. MCF7 breast cancer cells conditionally expressing the EMT master regulator SNAI1 were used to identify early expressed microRNAs (miRNAs) and their targets that may contribute to the EMT process. Potential targets of miRNAs were identified by matching lists of in silico predicted targets and of inversely expressed mRNAs.

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Background: Initially detected in leukocytes and cancer cells derived from solid tissues, L-plastin/fimbrin belongs to a large family of actin crosslinkers and is considered as a marker for many cancers. Phosphorylation of L-plastin on residue Ser5 increases its F-actin binding activity and is required for L-plastin-mediated cell invasion.

Methodology/principal Findings: To study the kinetics of L-plastin and the impact of L-plastin Ser5 phosphorylation on L-plastin dynamics and actin turn-over in live cells, simian Vero cells were transfected with GFP-coupled WT-L-plastin, Ser5 substitution variants (S5/A, S5/E) or actin and analyzed by fluorescence recovery after photobleaching (FRAP).

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A novel mathematical model of the actin dynamics in living cells under steady-state conditions has been developed for fluorescence recovery after photobleaching (FRAP) experiments. As opposed to other FRAP fitting models, which use the average lifetime of actins in filaments and the actin turnover rate as fitting parameters, our model operates with unbiased actin association/dissociation rate constants and accounts for the filament length. The mathematical formalism is based on a system of stochastic differential equations.

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We used a tumour necrosis factor (TNF)-alpha resistant breast adenocarcinoma MCF-7 cell line to investigate the involvement of the actin cytoskeleton in the mechanism of cell resistance to this cytokine. We found that TNF resistance correlates with the loss of cell epithelial properties and the gain of a mesenchymal phenotype, reminiscent of an epithelial-to-mesenchymal transition (EMT). Morphological changes were associated with a profound reorganization of the actin cytoskeleton and with a change in the repertoire of expressed actin cytoskeleton genes and EMT markers, as revealed by DNA microarray-based expression profiling.

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L-plastin, a conserved modular F-actin bundling protein, is ectopically expressed in tumor cells and contributes to cell malignancy and invasion. The underlying molecular mechanisms involved remain unclear, in part, because specific inhibitors of L-plastin are lacking. We used recombinant alpaca-derived L-plastin single-domain antibodies (nanobodies) as effector of L-plastin function in cells.

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The transcription regulator SNAI1 triggers a transcriptional program leading to epithelial to mesenchymal transition (EMT), providing epithelial cells with mesenchymal features and invasive properties during embryonic development and tumor progression. To identify early transcriptional changes occurring during SNAI1-induced EMT, we performed a time-resolved genome-scale study using human breast carcinoma cells conditionally expressing SNAI1. The approach we developed for microarray data analysis, allowed identifying three distinct EMT stages and the temporal classification of genes.

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We report on an advanced universal Monte Carlo simulation model of actin polymerization processes offering a broad application panel. The model integrates major actin-related reactions, such as assembly of actin nuclei, association/dissociation of monomers to filament ends, ATP-hydrolysis via ADP-Pi formation and ADP-ATP exchange, filament branching, fragmentation and annealing or the effects of regulatory proteins. Importantly, these reactions are linked to information on the nucleotide state of actin subunits in filaments (ATP hydrolysis) and the distribution of actin filament lengths.

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Micro(mi)RNAs are small noncoding RNAs that orchestrate many key aspects of cell physiology and their deregulation is often linked to distinct diseases including cancer. Here, we studied the contribution of miRNAs in a well-characterized human myeloid leukemia, acute promyelocytic leukemia (APL), targeted by retinoic acid and trioxide arsenic therapy. We identified several miRNAs transcriptionally repressed by the APL-associated PML-RAR oncogene which are released after treatment with all-trans retinoic acid.

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Background: Image analysis of microarrays and, in particular, spot quantification and spot quality control, is one of the most important steps in statistical analysis of microarray data. Recent methods of spot quality control are still in early age of development, often leading to underestimation of true positive microarray features and, consequently, to loss of important biological information. Therefore, improving and standardizing the statistical approaches of spot quality control are essential to facilitate the overall analysis of microarray data and subsequent extraction of biological information.

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The actin-binding protein gelsolin is involved in cell motility via the regulation of actin cytoskeleton, and its expression is modified in several human cancers. However, the potential implication of this protein in colorectal carcinogenesis is debated. By using immunohistochemistry, we studied gelsolin expression in 69 cases of colon adenocarcinomas and in 72 lesions representative of the different stages of colonic tumorigenesis.

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Background: The actin cytoskeleton plays a crucial role in supporting and regulating numerous cellular processes. Mutations or alterations in the expression levels affecting the actin cytoskeleton system or related regulatory mechanisms are often associated with complex diseases such as cancer. Understanding how qualitative or quantitative changes in expression of the set of actin cytoskeleton genes are integrated to control actin dynamics and organisation is currently a challenge and should provide insights in identifying potential targets for drug discovery.

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Bardet-Biedl syndrome (BBS) is primarily an autosomal recessive ciliopathy characterized by progressive retinal degeneration, obesity, cognitive impairment, polydactyly, and kidney anomalies. The disorder is genetically heterogeneous, with 11 BBS genes identified to date, which account for ~70% of affected families. We have combined single-nucleotide-polymorphism array homozygosity mapping with in silico analysis to identify a new BBS gene, BBS12.

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L-plastin, a malignant transformation-associated protein, is a member of a large family of actin filament cross-linkers. Here, we analysed how phosphorylation of L-plastin on Ser5 of the headpiece domain regulates its intracellular distribution and its interaction with F-actin in transfected cells and in in vitro assays. Phosphorylated wild-type L-plastin localised to the actin cytoskeleton in transfected Vero cells.

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Actin-related proteins (ARPs) are key players in cytoskeleton activities and nuclear functions. Two complexes, ARP2/3 and ARP1/11, also known as dynactin, are implicated in actin dynamics and in microtubule-based trafficking, respectively. ARP4 to ARP9 are components of many chromatin-modulating complexes.

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T- and L-plastin are highly similar actin-bundling proteins implicated in the regulation of cell morphology, lamellipodium protrusion, bacterial invasion and tumor progression. We show that T-plastin localizes predominantly to the cytoplasm, whereas L-plastin distributes between nucleus and cytoplasm in HeLa or Cos cells. T-plastin shows nuclear accumulation upon incubation of cells with the CRM1 antagonist leptomycin B (LMB).

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Increasing evidence suggests that actin cross-linking or bundling proteins might not only structure the cortical actin cytoskeleton but also control actin dynamics. Here, we analyse the effects of T-plastin/T-fimbrin, a representative member of an important actin-filament cross-linking protein by combining a quantitative biomimetic motility assay with biochemical and cell-based approaches. Beads coated with the VCA domain of the Wiskott/Aldrich-syndrome protein (WASP) recruit the actin-nucleating Arp2/3 complex, polymerize actin at their surface and undergo movement when placed in cell-free extracts.

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Dynamic processes such as cell migration and division depend on the actin cytoskeleton, a dense meshwork of protein polymers capable of undergoing rapid cycles of assembly and disassembly, under the control of a large number of actin-associated proteins. In cancer cells, structural and functional perturbations of the actin cytoskeleton correlate with higher proliferation rates and uncontrolled movement. Therefore, small molecules that act on the actin cytoskeleton of tumour cells and thus inhibit cell division and movement, may be of high therapeutic value.

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