Biology subjects

Monnot, C.

Publications and source records attributed to Monnot, C..

4 recordsLinked to original sources

bioRxiv2025

Adaptation of endothelial cells to microenvironment topographical cues through lysyl oxidase like-2-mediated basement membrane scaffolding

Basement membrane (BM) provides structural support and signaling platform for blood vessels. While its major structural components are required for vascular morphogenesis, integrating BM regulators, like the lysyl oxidase LOXL2, and BM assembly in cell response to microenvironement cues remain poorly understood. Here we study the early deposition and supramolecular assembly of BM components using correlative atomic force and fluorescence microscopy. The fibrillar deposition of fibronectin is gradually remodeled and associates with the collagen IV meshwork as it organizes into BM. We demonstrate that LOXL2 is deposited with both proteins and participates in their remodeling. Alteration of BM scaffolding by LOXL2-depletion affects focal adhesion maturation and cytoskeleton remodeling. This altered BM organization maintains stress fibers, affects the distribution and activation of mechanosensors and alters cell barrier properties. Furthermore, using 3D micro-printed substrates, we demonstrate that BM assembly regulates endothelial cell response to topographical constraint. We therefore propose a mechanism directly linking the scaffolding of BM components and adaptation to the topographical signals from the microenvironment.

cell biology↗

bioRxiv2025

3D vascularized microtumors unveil aberrant ccRCC vasculature and differential sensitivity to targeted treatments

Clear cell renal cell carcinoma (ccRCC) is largely driven by Von Hippel Lindau (VHL) protein deficiency, promoting epithelial-mesenchymal transition, invasion, and hypervascularization, mediated by vascular endothelial growth factor (VEGF) signaling resulting in a structurally abnormal capillary network, which remains insufficiently defined. Previous studies correlating patient outcome with microvascular density yielded diverse results, underscoring the limitations of conventional parameters to fully capture vascular complexity. While VEGF-targeted anti-angiogenic first-line therapies such as sunitinib prolong progression-free survival in metastatic ccRCC, their efficacy is hampered by resistance mechanisms. This study aims to elucidate the three-dimensional architecture of ccRCC-specific vasculature in the tumor microenvironment, and its response to targeted therapies. Analysis of human ccRCC samples identified two distinct vascular structures, markedly differing from tumor capillaries, termed ponds and sheets, which were further characterized in patient-derived xenografts using advanced 3D microscopy on optically cleared samples. Ponds are large, dilated, irregular structures with wide cavity, whereas sheets are thin, elongated, and collapsed structures. To further dissect endothelial network morphogenesis, we developed an innovative in vitro 3D vascularized microtumor model, faithfully recapitulating the aberrant pond architecture. Dynamic live imaging unraveled the temporal relationship between tumor invasion and pond morphogenesis. Additionally, drug sensitivity assays demonstrated that ponds exhibit lower responsiveness to sunitinib compared to tumor capillaries. Altogether, our 3D model not only captures a specific architecture of ccRCC vascular network but also provides mechanistic insight into its development and therapeutic sensitivity. This model offers a promising avenue for personalized treatment assessment and for identification of novel therapeutic strategies. Statement of significanceA co-culture-engineered model integrating tumor spheroid invasion and capillary morphogenesis recapitulates the ccRCC endothelial structures and their response to treatments.

cancer biology↗

bioRxiv2024

Quantifying Cell Traction Forces at the Individual Fiber Scale in 3D: A Novel Approach Based on Deformable Photopolymerized Fiber Arrays

The forces exerted by cells upon the fibers of the extracellular matrix play a decisive role in cell motility in development and disease. How the local physical properties of the matrix (such as density, stiffness, orientation) affect cellular forces remains poorly understood. Existing approaches to measure cell 3D traction forces within fibrous substrates lack control over the local properties and rely on continuum approaches, not suited for measuring forces at the scale of individual fibers. A novel approach is proposed here to fabricate multilayer arrays of deformable fibers with defined geometrical and mechanical properties using two-photon polymerization. The fibers are characterized using Atomic Force Microscopy and span a wide range of sizes and mechanical properties. This approach is combined with a new reference-free method for measuring traction forces in 3D, which relies on automated segmentation of the fibers coupled with finite element modeling. The force measurement pipeline is applied to study forces exerted by adherent cells, endothelial cells, fibroblasts or macrophages, and reveals how these forces are influenced by fiber density and stiffness. Additionally, coupling to fast volumetric imaging with lattice light-sheet microscopy enables the measurement of the low-intensity and short-lived tractions exerted by amoeboid cells, such as dendritic cells.

biophysics↗

bioRxiv2020

Papillary And Reticular Fibroblasts Generate Distinct Microenvironments That Differentially Impact Angiogenesis

Papillary and reticular dermis show distinct extracellular matrix (ECM) and vascularization, and fibroblasts isolated from these compartments have different gene expression patterns and behaviour in vitro. However, due to lack of relevant models, the contribution of skin fibroblast sub-populations to vascularization remains unknown. We thus cultured human papillary and reticular fibroblasts as cell sheets. Differential transcriptomic analysis was performed by RNA sequencing to characterize their microenvironment. Bioinformatic analysis revealed that each fibroblast population expressed specific angiogenesis and matrisome gene expression signatures resulting in specific ECM that differed both in composition and structure. The impact of secreted and ECM-bound factors was then assessed using 3D angiogenesis assays. When co-cultivated with endothelial cells, the papillary and reticular microenvironments induced the formation of distinct capillary networks mimicking the characteristics of vasculature of native dermis subcompartments (vessel diameter and density, number of branch points). Whereas conditioned media of papillary fibroblasts displayed intrinsic high angiogenic potential, reticular ones only contributed to capillary formation induced by exogenous VEGF. These results show that skin fibroblast populations regulate angiogenesis via both secreted and ECM-bound factors. Our work emphasizes the importance of papillary and reticular fibroblasts, not only for modelling dermis microenvironment but also for its vascularization.

cell biology↗