Biology subjects

Biro, M.

Publications and source records attributed to Biro, M..

7 recordsLinked to original sources

bioRxiv2025

Anillin-dependent actin assembly at PML NBs protects genome stability

Nuclear filamentous actin (F-actin) is emerging as a key regulator of genome stability1-6. During replication stress, transient bursts of nuclear actin assembly in S-phase promote fork remodelling and repair3,4, but how these bursts are initiated, regulated, and whether nuclear F-actin also act on DNA lesions inherited across cell cycles, remains unknown. Here, we show that replication stress induces nuclear actin assembly at liquid-liquid phase-separated (LLPS) promyelocytic leukaemia nuclear bodies (PML NBs), driven by the actin-binding protein Anillin. Although best known as a cytokinesis factor, Anillin localises to PML NBs in interphase, where it concentrates monomeric actin (G-actin) and establishes a favourable environment for spontaneous actin assembly. Filament growth within these condensates remodels PML NB morphology and composition, releasing sequestered AKT into the nucleoplasm. AKT is subsequently phosphorylated and activated, and this nuclear AKT activity is required to regulate 53BP1 nuclear bodies in G1. These protective LLPS compartments shield under-replicated DNA inherited from the stressed S-phase until the following S-phase. This prevents premature engagement by aberrant repair pathways that would otherwise generate toxic intermediates and culminate in mitotic failure. Together, these findings define a condensate-to-filament pathway in which nuclear F-actin dynamically reorganises phase-separated compartments to safeguard genome stability across cell cycles.

cell biology↗

bioRxiv2025

Fluorescently Labeled Gradient Hydrogels Reveal Matrix-Dependent Cell Responses to Substrate Stiffness

Microfabricated stiffness gradient hydrogels hold significant value for advancing mechanobiology, tissue engineering, and in vitro tissue models. However, it remains challenging to design these materials given their broad processing parameter space. The continuum of stiffness values also makes it difficult to precisely correlate the local substrate properties and observed biological responses, often relying on cumbersome characterization methods such as atomic force microscopy. To address these bottlenecks, we present a straightforward thermophoresis-based fabrication strategy to pattern stiffness gradients in fluorescein isothiocyanate-labeled hydrogel network, which displays a polymer concentration-dependent fluorescence readout. This approach enables quantitative assessment of the gradient formation process and contactless stiffness mapping via standard microscopy imaging. Using gelatin methacryloyl and Gellan gum as model systems, it is shown that substrate stiffness and extracellular matrix protein composition work together to affect 3T3-L1 fibroblast cell morphology and migration, with the underlying hydrogel type also affecting the outcome. By offering a simple and reliable approach for characterizing stiffness gradient hydrogels, this work advances the thermophoretic fabrication platform, opening avenues for new biomaterial systems for understanding and controlling the cell-material interplay.

bioengineering↗

bioRxiv2024

Single molecule fingerprinting reveals different growth mechanisms in seed amplification assays for different polymorphs of alpha Synuclein fibrils.

Alpha-synuclein (Syn) aggregates, detected in the biofluids of patients with Parkinsons disease, have the ability to catalyze their own aggregation, leading to an increase in the number and size of aggregates. This self-templated amplification is used by newly developed assays to diagnose Parkinsons disease and turned the presence of Syn aggregates into a biomarker of the disease. It has become evident that Syn can form fibrils with slightly different structures, called "strains" or polymorphs, but little is known about their differential reactivity in diagnostic assays. Here we compared the properties of two well-described Syn polymorphs. Using single molecule techniques, we observed that one of the polymorphs had an increased tendency to undergo secondary nucleation and we showed that this could explain the differences of reactivity observed in in vitro seed amplification assay and cellular assays. Simulations and high-resolution microscopy suggest that a 100-fold difference in apparent rate of growth can be generated by a surprisingly low number of secondary nucleation "points" (1 every 2,000 monomers added by elongation). When both strains are present in the same seeded reaction, secondary nucleation displaces proportions dramatically and causes a single strain to dominate the reaction as the major end-product.

neuroscience↗

bioRxiv2023

Successful gall induction by Diplolepis rosae and D. mayri on the sweet briar (Rosa rubiginosa) under laboratory conditions

O_LIPlant galls are unique outgrowths caused by various organisms, including insects, serving as nourishment for the inducers larvae. Despite the taxonomists and ecologists attempts to elucidate the mechanisms behind plant gall formation, its understanding is still incomplete. Modern genetic techniques allow in depth analysis of the molecular processes, but variations across species entangle the analysis. Establishing laboratory-friendly plant-gall inducer communities is crucial, yet past attempts have faced challenges. C_LIO_LIOur study aimed to create a sustainable laboratory community involving wild roses (Rosa sp.) and as gall-inducing insects rose gall wasps belonging to the genus Diplolepis. Controlled indoor conditions were optimized for plant growth. Wild roses were transplanted, then exposed to gall inducers, and monitored. C_LIO_LISuccessfully initialized gall growth was measures and analysed, revealing insights into the impact of plant vigour on gall size. C_LIO_LIOur study successfully established a novel laboratory community for further research on gall formation mechanisms. C_LI

ecology↗

bioRxiv2021

Niche-guided tissue patterning by chemomechanical flow lithography

Stem-cell derived tissue models are commonly cultured under globally-delivered stimuli that trigger histogenesis via self-organizing activity. However, the culture of such tissue models is prone to stochastic behavior, limiting the reproducibility of cellular composition and resulting in non-physiological architectures. To overcome these shortcomings, we developed a method for printing cell niche microenvironments with microstructured cues that mediate local histogenic processes, including mechanosensing and differentiation of selected cell types. Microstructured cues include independently tunable mechano-chemical properties, with conjugated peptides, proteins, and morphogens across a range of Youngs moduli. By rationally designing niches, we mediate the structure of tissues derived from stem-cell-progenitor sources, including a bone-fat assembly from stromal mesenchyme, and embryonic tissues derived from hiPSC. We show that microstructured cues can recapitulate mechano-chemical signals resembling early embryonic histogenesis. This outcome includes a role for niche mechanics in human embryonic organization, where soft niche mechanics bias markers of mesendodermal differentiation and epithelial-to-mesenchymal-transition (EMT), as well as a demonstration of a material-mediated morphogen signaling centers able to induce foci of mesenchymal and EMT differentiation. Thus, microstructured materials can mediate local histogenic processes to enhance the structure and composition of tissue models.

bioengineering↗

bioRxiv2020

A Method to sort heterogenous cell populations based on migration in 2D and 3D environments

Whereas phenotypic assays such as Boyden chambers and wound healing assays can easily be employed to characterize the migratory potential of cells at the population level, few methods exist that can sort subpopulations of cells based on their migratory behaviour from an initial heterogeneous pool. In this paper, we present an approach to sort migratory cancer and immune cells based on their spontaneous migration in 2D and 3D microenvironments. Using this method, which is easy to implement and readily scalable, millions of live cells can be sorted based on their migratory characteristics and then subjected to downstream genomic, molecular and functional tests. We reveal that enrichment of the most migratory cytotoxic T lymphocytes yields a pool of cells with enhanced cytotoxicity against cancer cells. This new functional sorting method opens new avenues for the precise characterization of the mechanisms underlying hitherto unexplained heterogeneities in migratory phenotypes within a cell population, and for the targeted enrichment of the most potent migratory leukocytes in immunotherapies.

cell biology↗

bioRxiv2018

Nuclear filamentous actin functions in the replication stress response

\"Replication stress\" describes phenomena that alter DNA replication rates 1-3. Multiple architectural challenges within the confined nuclear volume must be navigated during replication to prevent or repair replication stress. Cellular mechanisms potentiating changes in nuclear architecture that facilitate DNA replication remain unclear. Here we show that the ATR, IPMK and mTOR kinases regulate actin polymerisation in human cells to alter nuclear architecture and promote replication fork repair. We demonstrate that replication stress activates mTOR, in an ATR and IPMK-dependent manner, to induce polymerisation of nuclear filamentous actin (F-actin). mTOR and ATR then counteract replication stress-induced nuclear envelope deformation and increase nuclear volume through their regulation of actin dynamics. Additionally, we reveal that FANCD2 labelled replication forks colocalise with actin filaments in late S-phase. mTOR and ATR then regulate the mobility, speed and directionality of stalled replication foci within the three-dimensional nuclear architecture. Importantly, we find nuclear F-actin also acts as a substrate for the directed migration of stalled replication foci to the nuclear periphery. Suppressing mTOR and ATR-dependent actin forces prevents replication fork restart and promotes chromosome segregation errors in primary and cancer cell lines. Together, these data reveal that ATR and mTOR regulate actin dynamics in the replication stress response to alter nuclear architecture and maintain genome stability.

cell biology↗