Biology subjects

Castellani, V.

Publications and source records attributed to Castellani, V..

8 recordsLinked to original sources

bioRxiv2026

LRRTM4 controls cell migration via Glypican interactions

Leucine-rich-repeat-transmembrane neuronal proteins (LRRTMs) play a major role in neuronal connectivity and synapse formation, but their function during early development remains largely unexplored and roles in cell migration have not been described. Here, we identify LRRTM4 as a major coordinator of cell migration within the developing cortex and in cancer cells. Using structural predictions and site-directed mutagenesis to abolish the LRRTM4-glypican interaction, we show that LRRTMs interact with the core domain of glypicans, which, in the midgestational murine cortex, are presented by radial glia cells. We demonstrate that glypican-bound LRRTM4 mediates contact-repulsion in migrating neurons and cancer cells in vitro. Our results demonstrate that LRRTMs are used by migrating cells responding to glypicans, and that this signaling system is active in migrating cancer cells and during development.

developmental biology↗

bioRxiv2024

Contribution of the neuron-specific ATP1A3 to embryonic spinal circuit emergence

The early neurodevelopmental contributions of ion pumps remain poorly characterized. Combining analysis of public human embryo single-cell transcriptomic datasets and an embryonic chicken model, we found a conserved differentiation sequence whereby spinal cord neurons switch on neuron-specific alpha3 subunit (ATP1A3) of Na+/K+ ATPases. In the chicken model, ATP1A3 is distributed along axons and growth cones. Its knockdown alters axon pathfinding of dorsal interneurons (DIN) that wire spinocerebellar circuits. In mirror of reported electric field (EF)-driven cell migration, we found that DIN axons align in EFs, which was abolished by Na+/K+ ATPase inhibitor Ouabain and ATP1A3 knockdown. We recorded an embryonic trans-neural-epithelial potential generating EF whose pharmacological and surgical manipulation mimicked ATP1A3 knock-down-induced altered DIN axon pathfinding. Using DINs transplantation paradigm, we found that ATP1A3 is required cell-autonomously for EF-mediated long-range guidance. Finally, dominant-negative ATP1A3 mutation causing an early ATP1A3 childhood disease disrupts this fundamental developmental process, revealing unexpected pathogenic mechanisms.

developmental biology↗

bioRxiv2023

Axon guidance during CNS regeneration is required for specific brain innervation

Reconstruction of functional neuronal circuits in the mature brain remains a big challenge in the field of central nervous system (CNS) repair. Despite achievement of robust, long-distance regeneration through modulation of specific neuronal intrinsic growth properties, functional recovery is still limited due to major guidance defects of regenerating axons. Using co-activation of mTOR, JAK/STAT and c-myc pathways in retinal ganglion cells (RGC), we highlight that regenerating axons avoid the suprachiasmatic nucleus (SCN) due to repulsive mechanisms. We show that Slit/Robo guidance signaling is responsible for this reinnervation failure. In vivo suppression of this repulsive signaling allows regenerating axons to enter the SCN. The newly formed circuit is associated with functional behavioral recovery. Our results provide evidence that axon guidance mechanisms are required in the context of mature neuronal circuit repair.

neuroscience↗

bioRxiv2023

Functional precision oncology for follicular lymphoma with patient-derived xenograft in avian embryos

BackgroundFollicular lymphoma (FL) is an incurable B-cell malignancy that constitutes a quarter of all lymphomas. Although RCHOP immuno-chemotherapy induces high rates of complete remission, almost all FL patients experience multiple relapses post-treatment. The limited understanding of treatment response heterogeneity is due to the absence of in vitro or in vivo experimental models, primarily because tumor cells heavily rely on their microenvironment to survive. In this study, we present an innovative xenograft model of primary FL cells in avian embryos, circumventing these limitations. MethodsWe developed the FL-AVI-PDX model by transplanting 20 biopsy FL samples, including good (n=11) and poor clinical responders (POD24, n=9), into chicken embryos. Each set of embryos was treated with RCHOP or vehicle intravenously. We evaluated the effect of immuno-chemotherapy on tumor volume by light sheet microscopy and on tumor biology by transcriptomic analysis at the single-cell level. ResultsWe successfully engrafted all samples in avian embryos. We found that RCHOP treatment in ovo led to tumor volume reduction, which predicted progression-free survival in multivariate analysis, demonstrating the models capacity to capture clinical heterogeneity at the patient level. The FL-AVI-PDX model also provided a unique opportunity to analyze the transcriptomic impact of RCHOP on FL cells using single-cell RNA sequencing. We identified a signature of 21 genes upregulated after RCHOP exposure, displaying significant intra-tumoral heterogeneity. As a proof of concept, we validated the functional involvement of BAX, a gene from the RCHOP-induced signature, as a critical effector of immuno- chemotherapy in vitro and in avian embryos. ConclusionsThe FL-AVI-PDX model is a platform for functional precision oncology in primary FL cells that captures both inter- and intra-patient heterogeneity of clinical response to a complex therapeutic regimen. It offers a unique opportunity to better understand FL biology, opening perspectives for the development of new drugs.

cancer biology↗

bioRxiv2022

An in vivo avian model of human melanoma to perform rapid and robust preclinical studies

Metastatic melanoma patients carrying a BRAFV600 mutation can be treated with BRAF inhibitors (BRAFi), in combination with MEK inhibitors (MEKi), but innate and acquired resistance invariably occurs. Resistance can involve transcriptional- and epigenetic-based phenotypic adaptations, as yet unpredictable. Predicting patient response to targeted therapies is crucial to guide clinical decision. We describe here the development of a highly efficient patient-derived xenograft model adapted to patient melanoma biopsies, using the avian embryo as a host (AVI-PDX). In this in vivo paradigm, we depict a fast and reproducible tumor engraftment of patient samples within the embryonic skin, preserving key molecular and phenotypic features. We show that sensitivity and resistance to BRAFi/MEKi targeted therapies can be reliably modeled in these AVI-PDX, as well as synergies with other drugs, such as HDACi. We further provide proof-of-concept that the AVI-PDX models the diversity of responses of melanoma patients to BRAFi/MEKi, within days, hence positioning it as a valuable tool for the design of personalized medicine assays and for the evaluation of novel combination strategies.

cancer biology↗

bioRxiv2021

Modeling breast cancer by grafting patient tumor samples in the avian embryo: an in vivo platform for therapy evaluation coupled to large scale molecular analyses

Lack of preclinical patient-derived xenograft (PDX) cancer models in which to conduct large scale molecular studies seriously impairs the development of effective personalized therapies. We report here on an in vivo concept consisting of implanting human tumor cells in targeted tissues of an avian embryo, delivering therapeutics, evaluating their efficacy by measuring tumors using light sheet confocal microscopy, and conducting large scale RNAseq analysis to characterize therapeutic-induced changes in gene expression. The model was established to recapitulate triple negative breast cancer (TNBC) and validated using TNBC standards of care (SOCs) and an investigational therapeutic agent.

cancer biology↗

bioRxiv2020

Iterative inhibition of commissural growth cone exploration, not post-crossing barrier, ensures forward midline navigation through SlitC-PlxnA1 signaling

Sensitization to Slits and Semaphorin (Sema)3B floor plate repellents after midline crossing is thought to be the mechanism expelling commissural axons contralaterally and preventing their back-turning. We studied the role of Slit-C terminal fragment sharing with Sema3B the Plexin (Plxn) A1 receptor, newly implicated in midline guidance. We generated a knock-in mouse strain baring PlxnA1Y1815F mutation altering SlitC but not Sema3B responses and observed recrossing phenotypes. Using fluorescent reporters, we found that Slits and Sema3B form clusters decorating an unexpectedly complex mesh of ramified FP glia basal processes spanning the entire navigation path. Time-lapse analyzes revealed that impaired SlitC sensitivity destabilized axon trajectories by inducing high levels of growth cone exploration from the floor plate entry, increasing risk of aberrant decisions. Thus, FP crossing is unlikely driven by post-crossing sensitization to SlitC. Rather, SlitC limits growth cone plasticity and exploration through reiterated contacts, continuously imposing a straight and forward-directed trajectory.

developmental biology↗

bioRxiv2019

Spatial and temporal profiling of receptor membrane insertion controls commissural axon responses to midline repellents

Accurate perception of guidance cues is crucial for axonal pathfinding. During their initial navigation in the spinal cord, commissural axons are kept insensitive to midline repellents. Through yet unclear mechanisms acting during midline crossing in the floor plate, they switch on responsiveness to various repulsive signals, that establish a permanent midline barrier and propel the axons for exit. Whether these gains of response are coupled to occur in synchrony or rather are independently activated through signaling-specific programs is fully unknown. We set-up a paradigm for live imaging and super resolution analysis of guidance receptor dynamics during commissural growth cone navigation in chick and mouse embryos. We uncovered a remarkable program of delivery and allocation of receptors at the growth cone surface, generating receptor-specific spatial and temporal profiles. This reveals a mechanism whereby commissural growth cones can discriminate coincident repulsive signals that they functionalize at different time points of their navigation.

developmental biology↗