Biology subjects

Lambert, R.

Publications and source records attributed to Lambert, R..

4 recordsLinked to original sources

bioRxiv2026

Scorpion toxin peptide BMK86-P1 achieves mutation-reversible inhibition of KCNA2 at the cost of reduced efficacy in heteromers and murine neurons

The discovery of distinctive function-phenotype relationships in monogenetic channelopathies has turned out to be critical for the development of precision medicine approaches. However, the best prediction of clinical phenotypes depends on neuronal function, where existing models lack tools to isolate currents of individual voltage-gated potassium channel subunits and differentiate variant effects in complex systems. Ideally, one should be able to overexpress subunit variants with an additional mutation that confers resistance against the tool to isolate the variant effect. Therefore, we solid-phase synthesized the KV1.2 specific scorpion toxin peptide BMK86-P1 and oxidized it with modest efficacy. In mammalian cells this BMK86-P1 selectively inhibited KV1.2 homomers, but not heteromers with KV1.1. Critically, the KCNA2 p.Val381Tyr mutation, which reverses BMK86-P1's selective inhibition of KV1.2, also altered the activation of KV1.2 homomers to resemble those of KV1.1. In addition, BMK86-P1 in murine neurons did not alter passive membrane properties, single action potential properties, or action potential firing. Surprisingly, it induced only minimal changes in spontaneous excitatory postsynaptic currents. In summary, this KV1.2 subunit selective toxin peptide asserts its effects primarily on homomeric channels, while only weakly inhibiting KV1.2-heteromeric channels and consequently preventing any meaningful impact on neuronal function. This highlights the limits of peptide synthesis together with the need for testing specific compounds on complex systems.

neuroscience↗

bioRxiv2024

Drug-induced cytotoxicity prediction in muscle cells, an application of the Cell Painting assay

In silico toxicity prediction offers the chance of reducing or replacing most animal testing through the integration of large experimental assay datasets with the appropriate computational approaches. The use of Cell Painting to detect various phenotypic changes induced by chemicals is emerging as a powerful technique in toxicity prediction. However, most Cell Painting approaches use cancer cells that are less relevant for many toxicological endpoints, which may limit the usefulness of this data. In this study, a myoblast cell line is used to characterize cellular responses to a panel of 30 known myotoxicants. In place of traditional structural descriptors, here each perturbation is described by a fingerprint of calculated properties, deducted from the intensity, shape, or texture of individual cells. We show that these kinds of descriptors convey information to allow the prediction of the cellular viability and fate of cells in myoblasts and differentiated myotubes of the C2C12 cell line, and the clustering of drugs by their cytotoxicity responses. Author SummaryStudying the toxicity of chemical compounds and drugs is crucial to avoid potentially lethal adverse effects of commercialized products, but also to detect the unsuspected toxicity of existing drugs. While these assays traditionally rely on animal models raising important ethical concerns, a need for in vitro and in silico models is present and increasing in recent years. We here propose a predictive model capable of predicting the values of a cell viability assay using cell morphology profiles captured with a microscopy experiment. This model predicts the healthiness of muscle cells treated with 30 compounds suspected to induce muscular damage or even myopathies in humans. We also use these profiles to find an interesting morphological similarity between two different classes of drugs: statins (used for cholesterol treatments) and tyrosine kinase inhibitors (anti-cancer drugs). This analysis opens a new perspective for understanding the mechanisms responsible for drug-induced muscular toxicity, an area of toxicology that is currently under-researched.

bioinformatics↗

bioRxiv2023

Depletion of LONP2 unmasks differential requirements for peroxisomal function between cell types and in cholesterol metabolism.

Peroxisomes play a central role in tuning metabolic and signaling programs in a tissue- and cell type-specific manner. However, the mechanisms by which the status of peroxisomes is communicated and integrated into cellular signaling pathways is not yet understood. Herein, we report the cellular responses to acute peroxisomal proteotoxic stress upon silencing the peroxisomal protease/chaperone LONP2. Depletion of LONP2 triggered accumulation of its substrates, alterations in peroxisome size and numbers, and luminal protein import failure. Gene expression changes and lipidomic analysis revealed striking cell specific differences in the response to siLONP2. Specific to COS-7 cells was a strong activation of the integrated stress response (ISR) and upregulation of ribosomal biogenesis gene expression levels. Common changes between COS-7 and U2OS cell lines included repression of the retinoic acid signaling pathway, and upregulation of sphingolipids. Cholesterol accumulated in the endomembrane compartments in both cell lines, consistent with evidence that peroxisomes are required for cholesterol flux out of late endosomes. These unexpected consequences of peroxisomal stress provide an important insight for our understanding of the tissue-specific responses seen in peroxisomal disorders.

cell biology↗

bioRxiv2021

Inactivated rabies virus vectored SARS-CoV-2 vaccine prevents disease in a Syrian hamster model.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emergent coronavirus that has caused a worldwide pandemic. Although human disease is often asymptomatic, some develop severe illnesses such as pneumonia, respiratory failure, and death. There is an urgent need for a vaccine to prevent its rapid spread as asymptomatic infections accounting for up to 40% of transmission events. Here we further evaluated an inactivated rabies vectored SARS-CoV-2 S1 vaccine CORAVAX in a Syrian hamster model. CORAVAX adjuvanted with MPLA-AddaVax, a TRL4 agonist, induced high levels of neutralizing antibodies and generated a strong Th1-biased immune response. Vaccinated hamsters were protected from weight loss and viral replication in the lungs and nasal turbinates three days after challenge with SARS-CoV-2. CORAVAX also prevented lung disease, as indicated by the significant reduction in lung pathology. This study highlights CORAVAX as a safe, immunogenic, and efficacious vaccine that warrants further assessment in human trials.

microbiology↗