Biology subjects

Robin, P.

Publications and source records attributed to Robin, P..

4 recordsLinked to original sources

bioRxiv2026

A validated neuronal SH-SY5Y platform reveals critical experimental variables for reproducible Aβ 1-42 self-assembly neurotoxicity assessment

Reliable in vitro evaluation of amyloid-{beta} (A{beta}) toxicity is essential for the development of anti-amyloid therapeutics, yet experimental workflows often lack standardization. In our previous work, we established a reproducible protocol for the synthesis, characterization and controlled aggregation of highly pure A{beta}1-42. Here, we address the biological component of this variability by evaluating the impact of neuronal differentiation and toxicity assays on A{beta}-induced neurotoxicity. SH-SY5Y cells were differentiated using retinoic acid and brain-derived neurotrophic factor, generating a neuron-like phenotype validated by immunofluorescence, gene expression profiling and resistance to H2O2-induced oxidative stress. Using this characterized model, we investigated the effects of non-aggregated and pre-aggregated A{beta}1-42 species on cell viability and transcriptional responses. Strikingly, A{beta} toxicity was highly dependent on the aggregation state of the peptide, the differentiation status of the target cells and the viability assay employed. Our results suggest that the lack of standardization in peptide quality, aggregation procedures, neuronal maturation and toxicity assessment represents a major source of variability in the amyloid field. Together, these findings provide a methodological framework to improve the reproducibility and translational relevance of in vitro screening strategies for anti-amyloid therapeutics.

neuroscience↗

bioRxiv2025

A self-limiting mechanotransduction feedback loop ensures robust organ formation

Organ morphogenesis uses mechanotransduction feedback loops to convert forces into gene expression changes that regulate cell mechanics. How these loops integrate with developmental programs to ensure robust outcomes remains unclear. We show Yap mechanotransduction establishes a self-limiting positive feedback loop for semicircular canal formation in zebrafish. Canal development proceeds through bud initiation, extension, and fusion within the otic epithelium. Local swelling of hyaluronan-rich extracellular matrix (ECM) in the bud activates Yap in a spatial pattern. Yap induces its target ccn1l1, promoting further ECM expansion to sustain bud extension. This feedback loop confers developmental robustness: graded knockdown of ccn1l1 reduces extension rate, yet canal formation persists and fails only with strong disruption. Critically, the loop contains its own termination mechanism. During bud fusion, PKA-CREB signaling, activated by an adhesion GPCR, gpr126, suppresses ccn1l1, ending the loop. These findings reveal how mechanotransduction loops with built-in termination provide developmental control by integrating mechanical forces, transcriptional responses, and morphogenetic outcomes.

developmental biology↗

bioRxiv2024

Charge distribution of coating brush drives inter-chromosome attraction

The condensation of charged polymers is an important driver for the formation of biomolecular condensates. Recent experiments suggest that this mechanism also controls the clustering of eukaryotic chromosomes during the late stages of cell division. In this process, inter-chromosome attraction is driven by the condensation of cytoplasmic RNA and Ki-67, a charged intrinsically disordered protein that coats the chromosomes as a brush. Attraction between chromosomes has been shown to be specifically promoted by a localized charged patch on Ki-67, although the physical mechanism remains unclear. To elucidate this process, we combine here coarse-grained simulations and analytical theory to study the RNA-mediated interaction between charged polymer brushes on the chromosome surfaces. We show that the charged patch on Ki-67 leads to inter-chromosome attraction via RNA bridging between the two brushes, whereby the RNA preferentially interacts with the charged patches, leading to stable, long-range forces. By contrast, if the brush is uniformly charged, bridging is basically absent due to complete adsorption of RNA onto the brush. Moreover, the RNA dynamics becomes caged in presence of the charged patch, while remaining diffusive with uniform charge. Our work sheds light on the physical origin of chromosome clustering, while also suggesting a general mechanism for cells to tune work production by biomolecular condensates via different charge distributions.

biophysics↗

bioRxiv2024

Lumen charge governs ion transport in β-barrel nanopores

{beta}-barrel nanopores are involved in crucial biological processes, from ATP export in mitochondria to bacterial resistance, and represent a promising platform for emerging sequencing technologies. However, in contrast to ion channels, the understanding of the fundamental principles governing ion transport through these nanopores remains in its early stages. In this study, we integrate experimental, numerical, and theoretical approaches to elucidate ion transport mechanisms in these biological nanopores. We identify and characterise two distinct nonlinear phenomena: open-pore rectification and gating. Through extensive mutation analysis of aerolysin nanopores, we demonstrate that open-pore rectification is caused by ionic accumulation driven by the distribution of lumen charges. Additionally, we provide converging evidence suggesting that gating is controlled by electric fields dissociating counterions from lumen charges, promoting local structural deformations. Our findings establish a rigorous framework for the characterisation and understanding of biological ion transport processes, enabling the design of adaptable biosensors. We illustrate this by optimizing an aerolysin mutant for computing applications, paving the way for novel nanofluidic technologies.

biophysics↗