F-actin dynamics couples sphingolipid metabolism to epithelial barrier integrity in chronic colitis

Medvedeva, S.; Popova, J.; Achasova, K.; Kulygina, J.; Nickelwart, E.; Suldina, L.; Morozova, K.; Osipenko, M.; Kozhevnikova, E.

doi:10.64898/2026.01.21.700747

bioRxiv · 10.64898/2026.01.21.700747

F-actin dynamics couples sphingolipid metabolism to epithelial barrier integrity in chronic colitis

Medvedeva, S.·Popova, J.·Achasova, K.·Kulygina, J.·Nickelwart, E.·Suldina, L.·Morozova, K.·Osipenko, M.·Kozhevnikova, E.

View original source ↗Export metadata ↓

Abstract

BackgroundIntestinal barrier dysfunction is a hallmark of inflammatory bowel diseases (IBD). This condition causes intoxication and immune hyperactivation. Understanding the events underlying epithelial barrier disruption during chronic inflammation is key to developing barrier-restoring therapies. Filamentous actin (F-actin) is essential for maintaining polarity and junctional integrity. However, the contribution of F-actin dynamics to IBD-associated barrier dysfunction remains unclear. ObjectiveWe aimed to examine actin cytoskeleton integrity during chronic colitis across mouse models and human patients and identify potential regulators of cytoskeleton dynamics. DesignF-actin and junctional proteins were analyzed in three models of chronic colitis (Muc2 KO, DSS-induced colitis, adoptive transfer colitis) using confocal microscopy. Claudin-3 interactors were identified by immunoprecipitation and proteomics. Intestinal organoids were used to assess the effect of F-actin disruption on barrier integrity. Metabolomic and gene expression analyses identified candidate pathways, further validated by chemical inhibition. Biopsies from patients with ulcerative colitis (UC) were examined using transmission electron microscopy and confocal microscopy. ResultsDisrupted actin dynamics emerged as a critical driver of epithelial barrier dysfunction in chronic colitis. An imbalance between polymeric and monomeric actin impaired barrier integrity in vivo and in 3D organoids. Immunoprecipitation identified actin and associated factors as the primary interactors of claudin-3 with reduced interaction during inflammation. Ceramide metabolism was revealed as a potential regulator of F-actin and intestinal barrier. In UC patients, we confirmed concurrent disruption of junctions and F-actin. ConclusionsF-actin dysregulation contributes to barrier dysfunction in IBD and targeting its modulators, including ceramide biosynthesis, represents a novel therapeutic strategy. WHAT IS ALREADY KNOWN ON THIS TOPICO_LIEpithelial damage and increased paracellular permeability are key characteristics of inflammatory bowel diseases. C_LIO_LIParacellular permeability is partially attributed to the downregulation of junction proteins but this mechanism does not explain all clinical observations. C_LIO_LIIn the Muc2 KO mouse model of chronic colitis, F-actin organization and membrane localization of tight junction protein claudin-3 are disrupted, although protein expression levels remain unchanged. C_LI WHAT THIS STUDY ADDSO_LIF-actin dynamics is impaired in the intestinal epithelium across three different mouse models of chronic colitis and IBD patients. C_LIO_LIDisruption of F-actin dynamics leads to impaired membrane localization of tight and adherens junction proteins and increased intestinal epithelial permeability in vivo and in colonic organoids. C_LIO_LIInhibition of ceramide biosynthesis rescues F-actin polymerization and intestinal barrier integrity in mouse chronic colitis models. C_LI HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICYO_LITargeting F-actin dynamics is a promising approach to improve gut epithelial integrity. C_LIO_LI"Ceramide-F-actin-junction" axis is proposed as one of the mechanisms behind epithelial barrier disruption in colitis. Therapeutic targeting of this axis represents a promising path for restoring gut integrity. C_LI

Explore related subjects

cell biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Medvedeva, S., Popova, J., Achasova, K., Kulygina, J., Nickelwart, E., Suldina, L., Morozova, K., Osipenko, M., Kozhevnikova, E.. 2026-01-23. F-actin dynamics couples sphingolipid metabolism to epithelial barrier integrity in chronic colitis. https://doi.org/10.64898/2026.01.21.700747

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Differential requirement for the Ire1 luminal domain in Candida albicans drug susceptibility and pathogenicity

The opportunistic human pathogen Candida albicans depends on the unfolded protein response (UPR) for cell wall integrity, antifungal tolerance, filamentous growth, and virulence. The UPR is driven by the conserved transmembrane sensor Ire1, which is activated either by misfolded proteins through its luminal domain or by lipid bilayer stress (LBS) through its transmembrane domain. In budding yeast, these two activation modes deploy divergent transcriptional programs. Whether the requirement for these two input domains is separable in C. albicans, where the cell membrane and cell wall are themselves the targets of major antifungal drug classes, remains unknown. Here, we engineered a C. albicans strain expressing Ire1 lacking an intact luminal domain (ire1{Delta}LD), which no longer detects proteotoxic stress. The ire1{Delta}LD strain grew in the presence of the azole antifungals fluconazole and miconazole but was highly sensitive to heat shock, cell wall stress, and the echinocandin caspofungin. It was also unable to sustain filamentous growth and showed reduced virulence in a Caenorhabditis elegans infection model. RNA sequencing revealed only modest changes to the steady-state transcriptome of ire1{Delta}LD cells. Together, these findings define a differential requirement for the input domains of C. albicans Ire1, uncoupling growth under azole-induced membrane stress from the cell wall, thermal, and virulence-associated outputs that depend on proteotoxic sensing, a distinction that could inform antifungal strategies targeting the UPR.

cell biology↗

bioRxiv2026

Nucleosome Core Allostery Governs Chromatin Recognition and Cell Fate

Nucleosomes regulate chromatin folding, accessibility, and factor recruitment. Current models primarily attribute these functions to histone tail modifications, while the core is largely viewed as a structural scaffold. Yet subtle changes within the nucleosome core can produce profound functional consequences, and the mechanisms underlying these effects remain unclear. Here, we describe nucleosome core allostery as a fundamental principle of chromatin regulation that amplifies the impact of minimal nucleosome variations. Leveraging natural differences between H2A.Z variants, we show that the nucleosome core encodes distinct conformational dynamics that propagate allosterically, thereby controlling nucleosome accessibility and recognition by chromatin factors. As a result, a single buried amino acid substitution alone is sufficient to reprogram nucleosome dynamics and bias cell identity. Our findings establish the nucleosome core as an allosteric regulatory module and provide a generalizable framework for how subtle variation within nucleosomes is amplified into diverse biological outcomes in development and disease.

cell biology↗

bioRxiv2026

A Novel Open-Source CellProfiler Pipeline for Automated, User-Friendly Hierarchical and K-Means Clustering of Microglial Morphology

Microglia represent a highly dynamic and heterogeneous cell type that is critically implicated in states of health and pathology. Microglial morphological subgroups have been identified that correspond to functional characteristics determining health-related outcomes. The identification of states based on morphological characteristics will therefore provide invaluable insights into the microglia-specific functional mechanisms driving treatment effects. The application of clustering analyses enables the detection of groupings within samples reflecting differences in morphological features. Here we propose the application of three custom-created modules to be used within the open-source software CellProfiler. These modules enable the automated detection of clusters present within the sample of microglia, as well as the assessment of the abundance of these clusters across conditions. The application of the analysis is conducted in a highly user-friendly manner, with a user interface integrated into the pipeline, enabling the performance of the analysis with only minimal user input. The workflow thereby includes the conduction of an outlier assessment, followed by hierarchical clustering and k-means clustering and the generation of interactive graphs to determine the number of microglia states present in the sample. Bar plots displaying the abundance of the microglia states across conditions included in the sample will be created. This approach will facilitate faster and more comparable detection of microglial morphological clusters across studies.

cell biology↗