Biology subjects

Abelanet, S.

Publications and source records attributed to Abelanet, S..

7 recordsLinked to original sources

bioRxiv2025

Glucocorticoids Modulate mRNA Translation Fate Through P-Body Dynamics

Processing bodies (P-bodies) are cytoplasmic, membraneless organelles that play a key role in regulating RNA translation. To identify new pathways controlling their formation, we conducted a Food and Drug Administration (FDA)-approved drug screen. We found that glucocorticoids, among the most prescribed medicines, significantly increase P-body numbers across diverse epithelial cell types. This effect was fully reversible after glucocorticoid withdrawal, illustrating the adaptive dynamics of P-bodies. Using genetic invalidation and rescue approaches, we demonstrated that this accumulation requires the Glucocorticoid Receptor alpha isoform. P-body accumulation was associated with the sequestration of P-body-specific-targeted mRNAs, altering their translation yield. Notably, this translational regulation depends on transcript sequence features rather than abundance, with AU-rich mRNA transcripts being sequestered and GC-rich mRNAs preferentially translated under glucocorticoid treatment. Furthermore, we linked the decrease of LSM14B, a negative regulator of P-bodies, under glucocorticoid treatment to P-body reshaping. Our results reveal that, beyond their known transcriptional activity, prolonged exposure to glucocorticoids influences mRNA post-transcription and translation through a nucleotide composition-based mechanism.

cell biology↗

bioRxiv2025

Human mammary 3D spheroid models uncover the role of filopodia in breaching the basement membrane to facilitate invasion

Basement membranes (BM) are thin, nanoporous sheets of specialized extracellular matrix (ECM) that line epithelial tissues. They are dynamic structures that serve multiple key functions, as evidenced by numerous diseases, including cancer progression, that are associated with their alterations. Our understanding of the BM and its communication with adjoining epithelial cells remains highly fragmented due to the BMs complex molecular architecture, the lack of molecular tools, limitations in utilizing high-resolution imaging techniques to BMs assembled on tissues, and the difficulty of assessing their functional contributions in vivo. Here, by combining multiple -omics analyses and advanced microscopy methodologies, we characterized the BM from two normal human mammary epithelial cell lines, MCF10 and HMLE, grown as spheroids in 3D matrices. Our findings indicate that the spheroids autonomously assemble a BM exhibiting all the molecular, structural, and biophysical characteristics of physiological BM. Using these minimalist model systems, we show for the first time that the laminins, perlecan, and the hemidesmosomes are all arranged along a shared porous lattice defined by the collagen IV molecular network. Next, we demonstrate that the invasion-promoting PSD4/EFA6B knockout, found in patients with breast cancer, decreases the expression of BM components and their assembly on the spheroid surface. We then show that invasive spheroids develop enlarged pores in the BM via filopodia-like plasma membrane extensions, which further expand in a protease-dependent manner, thereby facilitating the passage of invasive cells. Significance StatementThe basement membrane (BM) directs epithelial tissue architecture and behavior. How tumor cells breach this barrier during invasion remains poorly understood. Using minimalist 3D spheroid models mimicking physiological BM assembly, we reveal a novel infiltration mechanism. Filopodia-like protrusions perforate and widen BM pores. This facilitates cell dissemination through sequential protease-independent and -dependent steps.

cell biology↗

bioRxiv2024

Cell culture differentiation and proliferation conditions influence the in vitro regeneration of the human airway epithelium

The human airway mucociliary epithelium can be recapitulated in vitro using primary cells cultured in an Air-Liquid Interface (ALI), a reliable surrogate to perform pathophysiological studies. As tremendous variations exist between media used for ALI-cultured human airway epithelial cells, our study aimed to evaluate the impact of several media (BEGMTM, PneumaCultTM, "Half&Half" and "Clancy") on cell type distribution using single-cell RNA sequencing and imaging. Our work revealed the impact of these media on cell composition, gene expression profile, cell signaling and epithelial morphology. We found higher proportions of multiciliated cells in PneumaCultTM-ALI and Half&Half, stronger EGF signaling from basal cells in BEGMTM-ALI, differential expression of the SARS-CoV-2 entry factor ACE2, and distinct secretome transcripts depending on media used. We also established that proliferation in PneumaCultTM-Ex Plus favored secretory cell fate, showing the key influence of proliferation media on late differentiation epithelial characteristics. Altogether, our data offer a comprehensive repertoire for evaluating the effects of culture conditions on airway epithelial differentiation and will help to choose the most relevant medium according to the processes to be investigated such as cilia, mucus biology or viral infection. We detail useful parameters that should be explored to document airway epithelial cell fate and morphology.

cell biology↗

bioRxiv2023

Mechano-dependent sorbitol accumulation supports biomolecular condensate

Biomolecular condensates regulate a wide range of cellular functions from signaling to RNA metabolism1, 2, yet, the physiologic conditions regulating their formation remain largely unexplored. Biomolecular condensate assembly is tightly regulated by the intracellular environment. Changes in the chemical or physical conditions inside cells can stimulate or inhibit condensate formation3-5. However, whether and how the external environment of cells can also regulate biomolecular condensation remain poorly understood. Increasing our understanding of these mechanisms is paramount as failure to control condensate formation and dynamics can lead to many diseases6, 7. Here, we provide evidence that matrix stiffening promotes biomolecular condensation in vivo. We demonstrate that the extracellular matrix links mechanical cues with the control of glucose metabolism to sorbitol. In turn, sorbitol acts as a natural crowding agent to promote biomolecular condensation. Using in silico simulations and in vitro assays, we establish that variations in the physiological range of sorbitol, but not glucose, concentrations, are sufficient to regulate biomolecular condensates. Accordingly, pharmacologic and genetic manipulation of intracellular sorbitol concentration modulates biomolecular condensates in breast cancer - a mechano-dependent disease. We propose that sorbitol is a mechanosensitive metabolite enabling protein condensation to control mechano-regulated cellular functions. Altogether, we uncover molecular driving forces underlying protein phase transition and provide critical insights to understand the biological function and dysfunction of protein phase separation.

cell biology↗

bioRxiv2022

VAP-A intrinsically disordered regions enable versatile tethering at membrane contact sites

Membrane contact sites (MCSs) between organelles are heterogeneous in shape, composition and dynamics. Despite this diversity, VAP proteins act as receptors for multiple FFAT motif-containing proteins and drive the formation of most MCSs involving the endoplasmic reticulum (ER). Although the VAP-FFAT interaction is well characterized, no model explains how VAP adapts to its partners in various MCSs. We report here that VAP-A localization to different MCSs depends on its intrinsically disordered regions (IDRs). We show that VAP-A interaction with PTPIP51 and VPS13A at ER-mitochondria MCS conditions mitochondria fusion by promoting lipid transfer and cardiolipin buildup. VAP-A also enables lipid exchange at ER-Golgi MCS by interacting with OSBP and CERT. However, removing IDRs from VAP-A restricts its distribution and function to ER- mitochondria MCS, at the expense of ER-Golgi MCS. Our data suggest that IDRs of VAP-A do not modulate its preference towards specific partners, but adjust its geometry to the constraints linked to different MCS organization and lifetime. Thus, VAP-A conformational flexibility mediated by its IDRs ensures membrane tethering plasticity and efficiency.

cell biology↗

bioRxiv2021

Tumor protein D54 binds intracellular nanovesicles via an amphipathic lipid packing sensor (ALPS) motif

Tumor Protein D54 (TPD54) is an abundant cytosolic protein that belongs to the TPD52 family, a family of four proteins (TPD52, 53, 54 and 55) that are overexpressed in several cancer cells. Even though the functions of these proteins remain elusive, recent investigations indicate that TPD54 binds to very small cytosolic vesicles with a diameter of ca. 30 nm, half the size of classical transport vesicles (e.g. COPI and COPII). Here, we investigated the mechanism of intracellular nanovesicle capture by TPD54. Bioinformatical analysis suggests that TPD54 contains a small coiled-coil followed by several amphipathic helices, which could fold upon binding to lipid membranes. One of these helices has the physicochemical features of an Amphipathic Lipid Packing Sensor (ALPS) motif, which, in other proteins, enables membrane binding in a curvature-dependent manner. Limited proteolysis, CD spectroscopy, tryptophan fluorescence and cysteine mutagenesis coupled to covalent binding of a membrane sensitive probe show that binding of TPD54 to small liposomes is accompanied by large structural changes in the amphipathic helix region. TPD54 binding to artificial liposomes is very sensitive to liposome size and to lipid unsaturation but is poorly dependent on lipid charge. Cellular investigations confirmed the key role of the ALPS motif in vesicle targeting. Surprisingly, the vesicles selected by TPD54 poorly overlap with those captured by the golgin GMAP-210, a long vesicle tether at the Golgi apparatus, which displays a dimeric coiled-coil architecture and an N-terminal ALPS motif. We propose that TPD54 recognizes nanovesicles through a combination of ALPS-dependent and -independent mechanisms.

cell biology↗

bioRxiv2020

Abnormal AMPAR-mediated synaptic plasticity, cognitive and autistic-like behaviors in a missense Fmr1 mutant mouse model of Fragile X syndrome

Fragile X syndrome (FXS) is the most frequent form of inherited intellectual disability and the best-described monogenic cause of autism. FXS is usually caused by a CGG-repeat expansion in the FMR1 gene leading to its silencing and the loss-of-expression of the Fragile X Mental Retardation Protein (FMRP). Missense mutations were also identified in FXS patients, including the recurrent FMRP-R138Q mutation. To investigate the mechanisms underlying FXS in these patients, we generated a knock-in mouse model (Fmr1R138Q) expressing the FMRP-R138Q protein. We demonstrate that the Fmr1R138Q hippocampus has an increased spine density associated with postsynaptic ultrastructural defects and increased AMPA receptor surface expression. Combining biochemical assays, high-resolution imaging and electrophysiological recordings, we also show that the mutation impairs the hippocampal long-term potentiation (LTP) and leads to socio-cognitive deficits in Fmr1R138Q mice. These findings reveal that the R138Q mutation impacts the synaptic functions of FMRP and highlight potential mechanisms causing FXS in FMRP-R138Q patients.

neuroscience↗