Biology subjects

Raynaud, F.

Publications and source records attributed to Raynaud, F..

9 recordsLinked to original sources

bioRxiv2026

Systematic comparison of gliflozins identifies a selective anti-calcifying effect of canagliflozin beyond canonical SGLT2 inhibition

Background: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) provide important cardiorenal benefits in chronic kidney disease (CKD), but their effects on vascular calcification remain conflicting. Whether potential anti-calcifying effects are shared across gliflozins or involve mechanisms beyond canonical SGLT2 inhibition is unknown. Methods: We systematically compared canagliflozin, dapagliflozin and empagliflozin in a high-phosphate diet-induced mouse model of vascular calcification and complementary ex vivo and in vitro models, including rodent and human vascular tissues and vascular smooth muscle cells (VSMCs). Aortic transcriptional response was investigated by RNA sequencing. VSMC calcification, proliferation, migration, viability, glucose uptake and bioenergetics were investigated using complementary cellular assays, including OsteoSense staining, Annexin V/propidium iodide staining, radiolabeled 2-deoxyglucose uptake and Seahorse ATP rate analysis. SGLT2/1 expression was examined by RT-qPCR, Western blotting and immunofluorescence. We also evaluated sotagliflozin, a dual SGLT1/2 inhibitor, and mizagliflozin, a selective SGLT1 inhibitor. Results: Among the three gliflozins, only canagliflozin significantly reduced aortic calcification in vivo. Its anti-calcifying effect was also observed in rodent aortic rings, human vascular explants, cultured VSMCs and aortic rings from diabetic db/db mice. Aortic RNA-seq revealed that canagliflozin partially reversed HPD-induced transcriptional alterations, including changes in pro-calcific signaling and cellular metabolism, while some endothelial and inflammatory responses were shared among gliflozins. In mouse VSMCs, canagliflozin reduced calcification across all tested concentrations, dose-dependently decreased osteogenic marker expression, and reduced proliferation and migration. Increased apoptotic and damaged cell fractions were observed at higher concentrations, but not at lower concentrations. Canagliflozin also reduced glucose uptake and mitochondrial ATP production, without significantly affecting glycolytic ATP production. Neither dapagliflozin nor empagliflozin reproduced these cellular and metabolic effects at any of the concentrations tested. SGLT2 and SGLT1 expression was low or undetectable in vascular tissues and cells, and neither sotagliflozin nor mizagliflozin reproduced the anti-calcifying effect of canagliflozin in vivo or in vitro. Conclusions: Canagliflozin exhibits a selective anti-calcifying profile among the gliflozins tested, associated with changes in VSMC responses and cellular metabolism. These findings suggest that its vascular protective effects may involve mechanisms beyond canonical SGLT2 inhibition.

pathology↗

bioRxiv2026

Cellular uptake of folate-olaparib conjugates via folate receptor-mediated endocytosis: Potential for selective delivery of DNA damage response inhibitors into tumour cells

The folate receptor (FR) is overexpressed in a range of human tumours including ovarian cancer cells. We propose that the overexpression of the FR on the surface of ovarian tumour cells could be exploited for the selective delivery of a DNA damage response inhibitor (DDRi) in the form of an intact folate drug conjugate (FDC). This approach would improve the therapeutic index of the parent DDRi facilitating combination studies of the DDRi-based FDC with DNA damaging chemotherapy. FR-mediated cellular uptake of the proposed folate drug conjugates is requisite for FDC selective delivery into tumours. In this study, we synthesised a series of olaparib-based folate conjugates that maintained the biochemical PARP1 inhibition associated with olaparib and showed binding affinity for the folate receptor. Significantly, we identified compounds 10b and 11 that selectively enter FR overexpressing tumour cells via folate receptor-mediated endocytosis in their intact form and engage with their target as demonstrated by the potent inhibition of PARylation (KB cells, PARylation IC50 = 5.7 and 3.9 nM; respectively).

biochemistry↗

bioRxiv2025

Balanced contractility and adhesion drive polarization in a minimal elastic actomyosin network

Polarization of migrating cells involves chemical and mechanical interactions of signaling networks, cytoskeleton, plasma membrane, and substrate adhesions. Still, it is not fully understood which mechanisms and components are sufficient for symmetry breaking, and if they work independently or together. Here, we use a discrete active network model to investigate if and how an elastic cytoskeletal network is capable of breaking symmetry solely through mechanical interactions. Our minimal model consists of elastic bonds, attractive force dipoles, and force-sensitive anchor points, initially distributed uniformly and subject to simple turnover rules. We find that these features are sufficient to produce different cell behaviors, and, remarkably, to drive symmetry breaking and directed (polarized) motion. Network behavior was primarily determined by the turnover rate of anchor points, which, itself, is a function of the ratio between dipole force and the threshold force required for anchor removal. Directional motion emerged at intermediate turnover rates, at which tension in the network accumulated through several turnover cycles before eventually exceeding the adhesion removal threshold locally at the edge, mirroring our recent experimental findings on correlation of the traction force with protrusion-retraction transitions in the cell [1, 2]. At high turnover rates, forces were unable to build up to sufficiently high levels, while at low turnover rates, anchors hinder motion. These results demonstrate how directed motion can emerge as an intrinsic property of a simple mechanical network, independently of external cues or complex signaling networks. Given the concordance between this model and recent experimental findings, we suggest that polarization by contraction-adhesion dynamics could be a fundamental emergent behavior of actin-myosin networks. Author summaryCells often need to move, for example, during development, wound healing, or immune responses. To do so, they must first decide where their "front" and "back" are, a process known as polarization. Most explanations for this behavior focus on complex chemical signaling inside the cell. In our work, we asked a simpler question: could mechanical forces within a cell be sufficient to make it polarize and move without an external cue? To explore this idea, we developed a computational model of a simplified cell made only of elastic connections, contractile forces, and attachment points to its surroundings. We started with a completely uniform system, without any built-in direction or external guidance. Surprisingly, we found that this minimal mechanical setup could spontaneously develop a front and a back and begin moving persistently. We proposed that the key mechanical factor controlling this behavior was the rate at which the attachment points break under mechanical load. When this process occurred at an intermediate rate, forces built up unevenly, leading to detachment and forward motion, similar to what is observed in-vitro. Our findings suggest that cell polarization and movement can emerge spontaneously from mechanical properties alone, highlighting an important and overlooked role for mechanics in cell behavior.

biophysics↗

bioRxiv2023

Characterizing fibrinolysis under flow conditions: a simplified mesoscale 3D model

One of the routine clinical treatments to eliminate ischemic stroke thrombi is injecting a biochemical product into the patients bloodstream, which breaks down the thrombis fibrin fibers: intravenous or intravascular thrombolysis. However, this procedure is not without risk for the patient; the worst circumstances can cause a brain hemorrhage or embolism that can be fatal. Improvement in patient management drastically reduced these risks, and patients who benefited from thrombolysis soon after the onset of the stroke have a significantly better 3-month prognosis, but treatment success is highly variable. The causes of this variability remain unclear, and it is likely that some fundamental aspects still require thorough investigations. For that reason, we conducted in vitro flow-driven fibrinolysis experiments to study pure fibrin thrombi breakdown in controlled conditions and observed that the lysis front evolved non-linearly in time. To understand these results, we developed an analytical 1D lysis model in which the thrombus is considered a porous medium. The lytic cascade is reduced to a second-order reaction involving fibrin and a surrogate pro-fibrinolytic agent. The model was able to reproduce the observed lysis evolution under the assumptions of constant fluid velocity and lysis occurring only at the front. For adding complexity, such as clot heterogeneity or complex flow conditions, we propose a 3-dimensional mesoscopic numerical model of blood flow and fibrinolysis, which validates the analytical models results. Such a numerical model could help us better understand the spatial evolution of the thrombi breakdown, extract the most relevant physiological parameters to lysis efficiency, and possibly explain the failure of the clinical treatment. These findings suggest that even though real-world fibrinolysis is a complex biological process, a simplified model can recover the main features of lysis evolution.

biophysics↗

bioRxiv2021

Investigating the two regimes of fibrin clot lysis: an experimental and computational approach

It has been observed in vitro that complete clot lysis is generally preceded by a period of latency during which the degradation seems to be inefficient. However, this latency was merely notified but not yet quantitatively discussed. In our experiments we observed that the lysis ubiquitously occurred in two distinct regimes, a slow and a fast lysis regime. We quantified extensively the duration of these regimes for a wide spectrum of experimental conditions and found that on average the slow regime lasts longer than the fast one, meaning that during most of the process the lysis is ineffective. We proposed a computational model in which the two regimes result from a spatially constrained kinetic of clot lysis: first the biochemical reactions take place at the outer core of the fibrin fibers composing the clot, then in the bulk resulting in the observed fast lysis regime. This simple hypothesis appeared to be sufficient to reproduce with a great accuracy the lysis profiles obtained experimentally. Our results shed light on new insights regarding the dynamical aspects of the lysis of fibrin rich clots in a context where the timing is so critical for patient treatment and outcome. SignificanceWhile the interplay between the main components of the fibrinolytic system is well understood, some dynamical aspects of the fibrinolysis remain unclear. Notably, we observe that in vitro fibrin rich clots undergo a slow and inefficient phase of degradation when subject to endogenous fibrinolysis. In fact, it turns out that a large part of the lysis process operates in this slow regime. To explain this observation, we proposed a computational model in which the properties of the binding of the proteins change during the lysis. First plasminogen and tissue plasminogen activator bind at the surface of the fibers, resulting in a slow lysis, then in the bulk of the fibers thus speeding up the degradation of the clot..

biophysics↗

bioRxiv2020

Restoring Glutamate receptosome dynamics at synapses rescues Autism-like deficits in Shank3-deficient mice.

Shank3 monogenic mutations lead to Autism Spectrum Disorders (ASD). Shank3 is part of the glutamate receptosome that physically links ionotropic NMDA receptors to metabotropic mGlu5 receptors through interactions with scaffolding proteins PSD95-GKAP-Shank3-Homer. A main physiological function of the glutamate receptosome is to control NMDA synaptic function that is required for plasticity induction. Intact glutamate receptosome supports glutamate receptors activation and plasticity induction, while glutamate receptosome disruption blocks receptors activity, preventing the induction of subsequent plasticity. Despite possible impact on metaplasticity and cognitive behaviors, scaffold interaction dynamics and their consequences are poorly defined. Here we used mGlu5-Homer interaction as a biosensor of glutamate receptosome integrity to report changes of NMDA synaptic function. Combining BRET imaging and electrophysiology, we show that a transient neuronal depolarization inducing NMDA-dependent plasticity disrupts glutamate receptosome in a long-lasting manner at synapses and induces signaling required for the expression of the initiated neuronal plasticity such as ERK and mTOR pathways. Glutamate receptosome disruption also decreases NMDA/AMPA currents ratio, freezing the sensitivity of the synapse to subsequent changes of neuronal activity. These data show the importance of a fine-tuning of protein-protein interactions within glutamate receptosome, driven by changes of neuronal activity, to control plasticity. In a mouse model of ASD, a truncated mutant form of Shank3 prevents the integrity of the glutamate receptosome. These mice display altered plasticity, anxiety-like and stereotyped behaviors. Interestingly, repairing the integrity of glutamate receptosome and its sensitivity to the neuronal activity rescued synaptic transmission, plasticity and some behavioral traits of Shank3{triangleup}C mice. Altogether, our findings characterize mechanisms by which Shank3 mutations cause ASD and highlight scaffold dynamics as new therapeutic target.

neuroscience↗

bioRxiv2019

Traction forces control cell-edge dynamics and mediate distance-sensitivity during cell polarization

Traction forces are generated by cellular actin-myosin system and transmitted to the environment through adhesions. They are believed to drive cell motion, shape changes, and extracellular matrix remodeling [1-3]. However, most of the traction force analysis has been performed on stationary cells, investigating forces at the level of individual focal adhesions or linking them to static cell parameters such as area and edge curvature [4-10]. It is not well understood how traction forces are related to shape changes and motion, e.g. forces were reported to either increase or drop prior to cell retraction [11-15]. Here, we analyze the dynamics of traction forces during the protrusion-retraction cycle of polarizing fish epidermal keratocytes and find that forces fluctuate in concert with the cycle, increasing during the protrusion phase and reaching maximum at the beginning of retraction. We relate force dynamics to the recently discovered phenomenological rule [16] that governs cell edge behavior during keratocyte polarization: both traction forces and the probability of switch from protrusion to retraction increase with the distance from the cell center. Diminishing traction forces with cell contractility inhibitor leads to decreased edge fluctuations and abnormal polarization, while externally applied force can induce protrusion-retraction switch. These results suggest that forces mediate distance-sensitivity of the edge dynamics and ultimately organize cell-edge behavior leading to spontaneous polarization. Actin flow rate did not exhibit the same distance-dependence as traction stress, arguing against its role in organizing edge dynamics. Finally, using a simple model of actin-myosin network, we show that force-distance relationship may be an emergent feature of such networks.

cell biology↗

bioRxiv2019

Signalling involving MET and FAK supports cell division independent of the activity of the cell cycle-regulating CDK4/6 kinases

Deregulation of the cyclin-dependent kinases 4 and 6 (CDK4/6) is highly prevalent in cancer yet inhibitors against these kinases currently show use in restricted tumour contexts. The extent to which cancers depend on CDK4/6 and what may undermine such dependency is poorly understood. Here we report that signalling engaging the MET proto-oncogene receptor tyrosine kinase/focal adhesion kinase (FAK) axis leads to CDK4/6-independent CDK2-activation, involving as a critical mechanistic events loss of the CDK inhibitor p21CIP1 and gain of its regulator, the ubiquitin ligase subunit SKP2. Combined inhibition of MET/FAK and CDK4/6 eliminates proliferation capacity of cancer cells in culture, and enhances tumour growth inhibition in vivo. Activation of the MET/FAK axis is known to arise through cancer extrinsic and intrinsic cues. Our work predicts that such cues support cell division independent of the activity of the cell cycle-regulating CDK4/6 kinases and identifies MET/FAK as a tractable route to broaden the utility of CDK4/6 inhibitor-based therapies in the clinic.

cancer biology↗

bioRxiv2017

Evolutionary dynamics and molecular features of intra-tumor heterogeneity

The systematic assessment of intra-tumor heterogeneity is still limited and often unfeasible. In silico investigations of large tumor cohorts can be used to decipher how multiple clones emerge and organize into complex architectures. Here, we addressed this challenge by integrating mathematical modeling of cancer evolution with algorithmic inference of clonal phylogenies in 2,600 human tumors from 15 tumor types. Through numerical simulations, we could discriminate between observable and hidden intra-tumor heterogeneity, the latter characterized by clones that are missed by DNA sequencing of human samples. To overcome this limitation in human tumors, we show that population frequencies of detectable clones can be used to estimate the extent of hidden heterogeneity. Overall, simulated and human clonal architectures were highly concordant and showed that high numbers of clones invariably emerge through branching lineages. Interestingly, high numbers of alterations were not necessarily associated with high intra-tumor heterogeneity. Indeed, tumors with alterations in proliferation-associated genes exhibited high numbers of clonal mutations, but few clones. Instead, mutations of chromatin remodeling genes characterized tumors with high numbers of subclonal alterations and multiple clones. Our results identify evolutionary and genetic determinants of tumor clonal architectures to guide functional investigations of intra-tumor heterogeneity.

cancer biology↗