Biology subjects

Etienne-Manneville, S.

Publications and source records attributed to Etienne-Manneville, S..

13 recordsLinked to original sources

bioRxiv2026

Transient cytoskeletal anisotropy encodes short-term mechanical memory

Cells can experience time-varying mechanical cues, particularly when navigating through changing and complex microenvironments. Yet whether and how cells retain and use a short-term mechanical memory of recent deformations remains unclear. Here we show that, in glioblastoma cells, this memory is encoded by transient cytoskeletal anisotropy. Using uniaxial magneto-mechanical actuation aligned or perpendicular to the cell long axis, nanoindentation, and selective cytoskeletal perturbations, we find that distinct architectures of the actin cytoskeleton drive opposite mechanical responses: actin stress fibers mediate stiffening under stretch, whereas the actin cortex underlies softening under perpendicular loading. Vimentin intermediate filaments are essential to stabilize actin organization under load, preserving deformation-specific mechanics. Quantitative imaging reveals that mechanical actuation induces network-specific alignment and anisotropy, stronger for actin than vimentin, that persists transiently after unloading and bias subsequent responses, revealing a short-lived, deformation-dependent mechanical memory. To integrate these observations, we develop a multi-network constitutive model that links cytoskeletal architecture and loading history to cell-scale mechanics, reproducing both the asymmetric mechanical responses and the measured reorganization dynamics. These findings provide a structural basis for short-term mechanical memory and suggest how cancer cells could exploit residual anisotropy to adapt to fluctuating solid stresses and confinement, transiently biasing polarization, force transmission, and directional persistence during invasion. They also identify vimentin-actin coupling and the kinetics of cytoskeletal remodeling as potential levers to limit the mechanical adaptability of invasive cancer cells.

biophysics↗

bioRxiv2025

KIAA1217/SKT is a centrosomal protein that regulates ciliogenesis

Centrosomes organize the microtubule network along the cell cycle and drive cilia assembly in resting cells to allow sensory or motility functions. Defects in cilia formation underlie ciliopathies and skeletal disorders, but the molecular regulators that couple centrosomes to signaling and cytoskeletal networks remain incompletely defined. Through BioID screening for CYLD interactors, we identify KIAA1217/SKT as a centrosomal and microtubule plus-end protein that also associates with focal adhesions. KIAA1217 loss in RPE-1 cells impaired ciliogenesis, producing fewer and shorter cilia. Domain mapping revealed an N-terminal centrosomal targeting domain and an EB1-dependent targeting of KIAA1217 to microtubule tips via C-terminal SxIP motifs. Importantly, defects caused by loss of KIAA1217 or its paralog p140Cap were rescued by inhibiting actin polymerization or Src activity, indicating regulation of actin polymerization through Src family activity. Together, our findings establish KIAA1217 as a positive regulator of ciliogenesis that integrates Src-dependent signaling, centrosomal architecture, and actin remodeling and may open new research avenues to understand KIAA1217-associated pathologies as vertebrate malformation and epithelia-mesenchymal transition. Centrosome, Ciliogenesis, Actin, Src family signaling, KIAA217/SKT, p140Cap

cell biology↗

bioRxiv2025

Intratumoral Heterogeneity of Vimentin Modulates Nuclear Mechanotransduction, DNA Damage Response and Cancer Cell Survival

Vimentin, a major intermediate filament protein, is essential for maintaining cellular integrity and regulating cytoskeletal dynamics. Its upregulation is a hallmark of epithelial-to-mesenchymal transition (EMT), a process that enhances cancer cell migration, invasion, and metastatic potential. However, single-cell transcriptomic analyses of glioblastoma, the most common and aggressive primary brain tumor, reveal that vimentin expression exhibits significant intratumoral heterogeneity, reflecting diverse cellular subpopulations that may contribute to tumor plasticity, therapy resistance, and disease progression. Here, we show that the absence of vimentin alters nuclear mechanotransduction in response to compression, leading to chromatin remodelling and profound changes in gene expression in cancer cells. Remarkably, we demonstrate that external compressive forces, akin to vimentin deficiency, disrupt DNA damage response pathways. This impairment compromises DNA damage sensing and repair, bypassing DNA damage checkpoints and apoptosis. Consequently, vimentin-negative tumor cells exhibit increased survival in response to physical stress and DNA damage, potentially driving radioresistance and further amplifying intratumoral heterogeneity.

cancer biology↗

bioRxiv2024

Lamins regulate nuclear mechanics and shape to control glioblastoma cell proliferation, migration and invasion

Glioblastoma (GBM) is known as the most aggressive brain tumor and is characterized by a high heterogeneity and a median patient survival time around 15 months. Phenotyping based on cell mechanics is increasingly recognized as a potential prognostic marker for tumor aggressiveness. We have previously shown that cell and nuclear mechanical properties vary between different grades of gliomas and may be used to differentiate between GBM of different aggressiveness. Here, we find that the levels of lamin proteins can serve as an indicator of GBM aggressiveness. In patient-derived GBM cell lines, we found that cells from different GBM express different lamin levels. Nuclear size correlates positively with the ratio between lamin A and lamin B1 while nuclear stiffness increases with the levels of both lamin A and lamin B1. A simple mechanical model suggests that lamin A and lamin B1 act like springs in series. We also show that cells proliferate faster in GBM cell lines expressing higher lamin A levels. Downregulating lamin A expression in these cells reverse the aggressive phenotype. In contrast with breast cancer cells for which reduced lamin A levels favor cell migration in a confined environment, increased levels of lamin A may facilitate the invasion of more aggressive GBM cell lines in the soft environment of the brain. Furthermore, since nuclear deformation is a hallmark of malignancy in cancer cells, our results suggest that nuclear shape and mechanics may serve as prognosis biomarkers for GBM.

biophysics↗

bioRxiv2023

A short sequence in the tail of SARS-CoV-2 envelope protein controls accessibility of its PDZ Binding Motif to the cytoplasm.

The carboxy terminal tail of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope protein (E) contains a PDZ-binding motif (PBM) which is crucial for coronavirus pathogenicity. During SARS-CoV-2 infection, the viral E protein is expressed within the Golgi apparatus membrane of host cells with its PBM facing the cytoplasm. In this work we study the molecular mechanisms controlling the presentation of the PBM to host PDZ (PSD-95/Dlg/ZO-1) domain-containing proteins. We show that at the level of the Golgi apparatus, the PDZ-binding motif of the E protein is not detected by E C-terminal specific antibodies neither by PDZ domain-containing protein binding partner. Four alanine substitutions upstream of the PBM in the central region of the E protein tail is sufficient to generate immunodetection by anti-E antibodies and trigger robust recruitment of the PDZ domain-containing protein into the Golgi organelle. Overall, this work suggests that the presentation of the PBM to the cytoplasm is under conformational regulation mediated by the central region of the E protein tail and that PBM presentation probably does not occur at the surface of Golgi cisternae but likely at post-Golgi stages of the viral cycle.

cell biology↗

bioRxiv2023

Specific subcellular localization drives the different functions of CDC42 isoforms during migration

The small G-protein CDC42 is an evolutionary conserved polarity protein and a key regulator of numerous polarized cell functions, including directed cell migration. In vertebrates, alternative splicing gives rise to two CDC42 proteins: the ubiquitously expressed isoform (CDC42u) and the brain isoform (CDC42b), whose specific roles are not fully elucidated. The two isoforms only differ in their carboxy-terminal sequence, which includes the CAAX motif essential for CDC42 interaction with membrane. Here we show that these divergent sequences do not directly affect the range of CDC42s potential binding partners, but indirectly influence CDC42-driven signaling by controlling the specific subcellular localization of the two isoforms. In astrocytes and neural precursors, which naturally express both variants, CDC42u is mainly cytosolic and associates with the leading-edge plasma membrane of migrating cells where it recruits the Par6-PKC{zeta} complex to fulfill its polarity function. In contrast, CDC42b mainly localizes to intracellular membrane compartments, where it interacts with N-WASP. CDC42b does not participate in cell polarization but embodies the major isoform regulating endocytosis. Both CDC42 isoforms act in concert by contributing their specific functions to promote chemotaxis of neural precursors, demonstrating that the expression pattern of the two isoforms is decisive for the tissue-specific behavior of cells.

cell biology↗

bioRxiv2021

Molecular organization and mechanics of single vimentin filaments revealed by super-resolution imaging

Intermediate filaments (IF) are involved in key cellular functions including polarization, migration, and protection against large deformations. These functions are related to their remarkable ability to extend without breaking, a capacity that should be determined by the molecular organization of subunits within filaments. However, this structure-mechanics relationship remains poorly understood at the molecular level. Here, using super-resolution microscopy (SRM), we show that vimentin filaments exhibit a ~49 nm axial repeat both in cells and in vitro. As unit-length-filaments (ULFs) were measured at ~59 nm, this demonstrates a partial overlap of ULFs during filament assembly. Using an SRM-compatible stretching device, we also provide evidence that the extensibility of vimentin is due to the unfolding of its subunits and not to their sliding, thus establishing a direct link between the structural organization and its mechanical properties. Overall, our results pave the way for future studies of IF assembly, mechanical and structural properties in cells.

biophysics↗

bioRxiv2020

A phospho-regulated ensemble signal motif of α-TAT1 drives dynamic microtubule acetylation

Spatiotemporally dynamic microtubule acetylation underlies diverse physiological events ranging from cell migration to intracellular trafficking, autophagy and viral infections. Despite its ubiquity, the molecular mechanisms that regulate the sole microtubule acetylating agent, -tubulin N-acetyltransferase 1 (-TAT1) remain obscure. Here we report that dynamic intracellular localization of -TAT1 unexpectedly determines the efficiency of microtubule acetylation. Specifically, we newly identified a conserved signal motif in the intrinsically disordered C-terminus of -TAT1, consisting of three competing regulatory elements - nuclear export, nuclear import and cytosolic retention. Their balance is tuned via phosphorylation by serine-threonine kinases including CDK1 and CK2. While the un-phosphorylated form resides both in the cytosol and nucleus, the phosphorylated form binds to specific 14-3-3 adapters and accumulates in the cytosol for maximal substrate access. Cytosolic localization of -TAT1 predominantly mediates microtubule acetylation, cell proliferation and DNA damage response. In contrast to other molecules with a similar phospho-regulated signal motif including transcription factors, -TAT1 uniquely uses the nucleus as a hideout. As amino acid mutations to the motif have been reported in cancer patients, the present mechanism of subcellular -TAT1 localization may help uncover a spatiotemporal code of microtubule acetylation in normal and aberrant cell functions.

cell biology↗

bioRxiv2020

Intracellular stiffening competes with cortical softening in glioblastoma cells

Cancer cell softening increases with the progression of the disease, suggesting that mechanical phenotyping could be used as a diagnostic or prognostic method. Here we investigate the cell mechanics of gliomas, brain tumors that originate from glial cells or glial progenitors. We use two microrheology techniques, a single cell parallel plates rheometer to probe whole cell mechanics and optical-tweezers to probe intracellular rheology. We show that cell mechanics discriminates human glioma cells of different grades. When probed globally, grade IV glioblastoma cells are softer than grade III astrocytoma cells, while they are surprisingly stiffer at the intracellular level. We explain this difference between global and local intracellular behaviours by changes in the composition and spatial organization of the cytoskeleton and by changes in nuclear mechanics. Our study highlights the need to combine rheology techniques for potential diagnostic or prognostic methods based on cancer cell mechanophenotyping.

biophysics↗

bioRxiv2020

Microtubules tune mechanosensitive cell responses

Mechanotransduction is a process by which cells sense the mechanical properties of their surrounding environment and adapt accordingly to perform cellular functions such as adhesion, migration and differentiation. Integrin-mediated focal adhesions are major sites of mechanotransduction and their connection with the actomyosin network is crucial for mechanosensing as well as the generation and transmission of forces onto the substrate. Despite having emerged as major regulators of cell adhesion and migration, the contribution of microtubules to mechanotransduction still remains elusive. Here, we show that actomyosin-dependent mechanosensing of substrate rigidity controls microtubule acetylation, a tubulin post-translational modification, by promoting the recruitment of the alpha-tubulin acetyl transferase (TAT1) to focal adhesions. Microtubule acetylation, in turn, promotes GEF-H1 mediated RhoA activation, actomyosin contractility and traction forces. Our results reveal a fundamental crosstalk between microtubules and actin in mechanotransduction, which contributes to mechanosensitive cell adhesion and migration.

cell biology↗

bioRxiv2019

A toxic palmitoylation on Cdc42 drives a severe autoinflammatory syndrome

BackgroundAutoinflammatory diseases (AID) result from dysregulation of the first lines of innate immune responses. Recently, development of high throughput genome sequencing technology led to the rapid emergence of important knowledge in the genetic field. About 20 genes have been identified so far in monogenic forms of distinct AID. However, 70-90 % of patients with AID remain without genetic diagnosis.\n\nObjectiveWe report the identification and characterization of a mutation in the C-terminal region of the Rho GTPase Cdc42 in a patient presenting a severe autoinflammatory phenotype.\n\nMethodsWe have analyzed the consequences of the mutation on the subcellular localization of the Cdc42 protein using imaging techniques. Molecular studies were performed using proteomic and biochemical experiments to provide mechanistic bases of the observed defects. Functional assays were also conducted using flow cytometry and cytokine production measurements.\n\nResultsWe show that mutant Cdc42 is trapped in the Golgi apparatus due to the aberrant addition of a palmitate that both enhances the interaction of mutant Cdc42 with Golgi membranes and inhibit its extraction by GDP dissociation inhibitor (GDI), thus impairing its cytosol/membrane shuttling. At the functional level, mutant Cdc42 fails to sustain actin filaments polymerization and induces an exacerbated profile of pro-inflammatory cytokine production due to increased NF-{kappa}B activation.\n\nConclusionsOur study now provides a molecular explanation for mutations that have been identified recently in our AID patient and others in the C-terminal part of Cdc42. Mutations located in this region of Cdc42 impair the intracellular localization of Cdc42, preventing its interaction with the plasma membrane. Thus, our results definitively link mutations in the CDC42 gene to a complex immune-hemato-autoinflammatory phenotype in humans.

genetics↗

bioRxiv2018

Microtubule acetylation but not detyrosination promotes focal adhesion dynamics and cell migration

Microtubules play a crucial role in mesenchymal migration by controlling cell polarity and the turnover of cell adhesive structures on the extracellular matrix. The polarized functions of microtubules imply that microtubules are locally regulated. Here, we investigated the regulation and role of two major tubulin post-translational modifications, acetylation and detyrosination, which have been associated with stable microtubules. Using primary astrocytes in a wound healing assay, we show that these tubulin modifications are independently regulated during cell polarization and differently affect cell migration. In contrast to microtubule detyrosination, TAT1-mediated microtubule acetylation increases in the vicinity of focal adhesions and promotes cell migration. We further demonstrate that TAT1 increases focal adhesion turnover by promoting Rab6-positive vesicle fusion at focal adhesions. Our results highlight the specificity of microtubule post-translational modifications and bring new insight into the regulatory functions of tubulin acetylation.

cell biology↗

bioRxiv2018

Intermediate filaments control collective migration by restricting traction forces and sustaining cell-cell contacts

Mesenchymal cell migration relies on the coordinated regulation of the actin and microtubule networks which participate in polarised cell protrusion, adhesion and contraction. During collective migration, most of the traction forces are generated by the acto-myosin network linked to focal adhesions at the front of leader cells, which transmit these pulling forces to the followers. Here, using an in vitro wound healing assay to induce polarisation and collective directed migration of primary astrocytes, we show that the intermediate filament (IF) network composed of vimentin, GFAP and nestin contributes to directed collective movement by controlling the distribution of forces in the migrating cell monolayer. Together with the cytoskeletal linker plectin, these IFs control the organisation and dynamics of the acto-myosin network, promoting the actin-driven treadmilling of adherens junctions, thereby facilitating the polarisation of leader cells. Independently of their effect on adherens junctions, IFs influence the dynamics and localisation of focal adhesions and limit their mechanical coupling to the acto-myosin network. We thus conclude that IFs promote collective directed migration by restricting the generation of traction forces to the front of leader cells, preventing aberrant tractions in the followers and by contributing to the maintenance of lateral cell-cell interactions.

cell biology↗