Biology subjects

Fricke, J.

Publications and source records attributed to Fricke, J..

4 recordsLinked to original sources

bioRxiv2026

Arp2/3 complex-dependent actin remodeling is required for efficient RSV uncoating in A549 cells

Productive human respiratory syncytial virus (RSV) cell-entry requires coordinated interactions between viral proteins and host-cell factors at the plasma membrane-actin cortex interface. Branched actin networks remodel this interface, but their precise contribution to the early stages of RSV infection remains unclear. Here, we interfered with Arp2/3 complex-dependent actin filament branching by generating A549 cell lines disrupted for expression of the essential Arp2 subunit by CRISPR/Cas9. Permanent loss of Arp2 reduced the infection of the RSV long GFP reporter virus as quantified over the first 24 h post-infection. Compromised infection efficiency in Arp2 knockout cells persisted at later time points and also resulted in reduced syncytia formation. Notably, these infection phenotypes were not accompanied by obvious changes in viral host cell attachment. Moreover, photoactivated localization microscopy (PALM) studies revealed comparable receptor diffusion and clustering in cells stably expressing mEos3.2-tagged insulin-like growth factor I receptor (IGF1R). Although Arp2/3-deficient cells displayed fewer albeit larger macropinosomes as compared to WT cells, no changes were observed for internalized RSV genome levels. In contrast, Arp2-deficient cells appeared suppressed in viral uncoating efficiency. Consequently, viral mRNA expression and the cellular type III interferon response were reduced. Together, these data reveal that Arp2/3 complex-dependent, branched actin networks contribute to the efficiency of RSV uncoating. ImportanceHuman respiratory syncytial virus (RSV) is a major cause of severe respiratory disease. The infection initiates at the plasma membrane-actin cortex interface, yet the role of actin in productive RSV entry has remained unclear. Using CRISPR/Cas9 disruption of the essential Arp2/3 complex subunit Arp2 in A549 cells, we show that branched actin networks are required for efficient RSV infection. Despite actin network remodeling, photoactivated localization microscopy showed unchanged diffusion and clustering of the RSV receptor IGF1R. Although macropinocytosis was affected in Arp2-deficient cells, RSV attachment and internalization were not influenced. In contrast, a {beta}-lactamase virus-like-particle-based assay revealed a defect in uncoating, followed by reduced viral gene expression and a weaker type III interferon response. These findings define Arp2/3 complex-dependent branched actin networks as a host determinant of RSV uncoating and provide a practical approach to quantify uncoating without engineering the RSV genome.

microbiology↗

bioRxiv2024

DNA walk of specific fused oncogenes exhibit distinct fractal geometric characteristics in nucleotide patterns

Background/ObjectivesThe complex system of cancer has led to an emphasis on understanding the more general causal relationship within the disease. In this context, concepts of symmetry and symmetry-breaking in distinct biological cell features or components have been examined as an approach to cancer investigation. However, there can be possible limitations in directly interpreting the symmetry-based approach from a physical viewpoint due to the lack of understanding of physical laws governing symmetry in complex systems like cancer. MethodsFractal geometry and DNA walk representation were employed to investigate the geometric features i.e., self-similarity and heterogeneity in DNA nucleotide coding sequences of wild-type and mutated oncogenes, tumour-suppressor, and other unclassified genes. The mutation-facilitated self-similar and heterogenous features were quantified by the fractal dimension and lacunarity coefficient measures, respectively. Additionally, the geometrical orderedness and disorderedness in the analyzed sequences were interpreted from the combination of the fractal measures. ResultsThe findings showed distinct fractal geometric features in the case of fusion mutations. It also highlights the possible interpretation of the observed fractal features as geometric analogues concerning explicit observations corresponding to specific cancer types. In addition, the two-dimensional multi-fractal analysis highlighted the presence of a single exponent in the scaling of mutation-mediated gene sequence self-similarity/complexity and heterogeneity. ConclusionsThe approach identified mutation-induced geometric features in gene sequences, demonstrating the potential of DNA walks and fractal analysis in translational research regarding cancer. The findings suggest that investigating fractal parameters can capture unique geometric features in nucleotide sequences, contributing to the understanding of cancers molecular complexity.

bioinformatics↗

bioRxiv2024

Comparison of the tolerability of terbium-161 and lutetium-177 in combination with somatostatin analogues in the preclinical setting

Purpose[177Lu]Lu-DOTATATE is an established somatostatin receptor (SSTR) agonist for the treatment of metastasized neuroendocrine neoplasms, while the SSTR antagonist [177Lu]Lu-DOTA-LM3 has only scarcely been employed in clinics. Impressive preclinical data obtained with [161Tb]Tb-DOTA-LM3 in tumor-bearing mice indicated the potential of terbium-161 as an alternative to lutetium-177. The aim of the present study was to compare the tolerability of 161Tb- and 177Lu-based DOTA-LM3 and DOTATATE in immunocompetent mice. MethodsDosimetry calculations were performed based on biodistribution data of the radiopeptides in immunocompetent mice. Treatment-related effects on blood cell counts were assessed on Days 10, 28 and 56 after application of [161Tb]Tb-DOTA-LM3 or [161Tb]Tb-DOTATATE at 20 MBq per mouse. These radiopeptides were also applied at 100 MBq per mouse and the effects compared to those observed after application of the 177Lu-labeled counterparts. Bone marrow smears, blood plasma parameters and organ histology were assessed at the end of the study. ResultsThe absorbed organ dose was commonly higher for the SSTR antagonist than for the SSTR agonist and for terbium-161 over lutetium-177. Application of a therapeutic activity level of 20 MBq [161Tb]Tb-DOTA-LM3 or [161Tb]Tb-DOTATATE was well tolerated without major hematological changes. The injection of 100 MBq of the 161Tb- and 177Lu-based somatostatin analogues affected the blood cell counts, however. The lymphocytes were 40-50% lower in treated mice compared to the untreated controls on Day 10 irrespective of the radionuclide employed. At the same timepoint, thrombocyte and erythrocyte counts were 30-50% and 6-12% lower, respectively, after administration of the SSTR antagonist (p<0.05) while changes were less pronounced in mice injected with the SSTR agonist. All blood cell counts were in the normal range on Day 56. Histological analyses revealed minimal abnormalities in the kidneys, liver and spleen of treated mice. No correlation was observed between the organ dose and frequency of the occurrence of abnormalities. ConclusionHematologic changes were more pronounced in mice treated with the SSTR antagonist than in those treated with the SSTR agonist. Despite the increased absorbed dose delivered by terbium-161 over lutetium-177, [161Tb]Tb-DOTA-LM3 and [161Tb]Tb-DOTATATE should be safe at activity levels that are recommended for their respective 177Lu-based analogues.

cancer biology↗

bioRxiv2021

A beta-glucosidase of an insect herbivore determines both toxicity and deterrence of a dandelion defense metabolite

Gut enzymes can metabolize plant defense metabolites and thereby affect the growth and fitness of insect herbivores. Whether these enzymes also influence herbivore behavior and feeding preference is largely unknown. We studied the metabolization of taraxinic acid {beta}-D-glucopyranosyl ester (TA-G), a sesquiterpene lactone of the common dandelion (Taraxacum officinale) that deters its major root herbivore, the common cockchafer larva (Melolontha melolontha). We demonstrate that TA-G is rapidly deglycosylated and conjugated to glutathione in the insect gut. A broad-spectrum M. melolontha {beta}-glucosidase, Mm_bGlc17, is sufficient and necessary for TA-G deglycosylation. Using plants and insect RNA interference, we show that Mm_bGlc17 reduces TA-G toxicity. Furthermore, Mm_bGlc17 is required for the preference of M. melolontha larvae for TA-G deficient plants. Thus, herbivore metabolism modulates both the toxicity and deterrence of a plant defense metabolite. Our work illustrates the multifacteted roles of insect digestive enzymes as mediators of plant-herbivore interactions.

ecology↗