ALD-R491 regulates vimentin filament stability and solubility, cell contractile force, cell migration speed and directionality

Structure and function of vimentin in the generation and secretion of extracellular vimentin in response to inflammation

The canonical functions of vimentin in cell mechanics and migration have been recently expanded by the discovery of new roles for extracellular vimentin (ECV) in immune responses to infection, injury and cancer. In contrast with the predominantly filamentous form of intracellular vimentin, ECV exists largely as soluble oligomers. The release of ECV from intact cells is dependent on mechanisms that regulate the assembly and disassembly of intracellular vimentin, which are influenced by discrete post-translational modifications. In this review we highlight the processes that promote the conversion of intracellular and insoluble vimentin filaments to ECV and secretion mechanisms. Insights into the regulation of ECV release from stromal and immune cells could provide new diagnostic and therapeutic approaches for assessing and controlling inflammatory diseases.

The Vimentin-Targeting Drug ALD-R491 Partially Reverts the Epithelial-to-Mesenchymal Transition and Vimentin Interactome of Lung Cancer Cells

Background: The epithelial-to-mesenchymal transition (EMT) is a common feature in early cancer invasion. Increased vimentin is a canonical marker of the EMT; however, the role of vimentin in EMT remains unknown. Methods: To clarify this, we induced EMT in lung cancer cells with TGF-β1, followed by treatment with the vimentin-targeting drug ALD-R491, live-cell imaging, and quantitative proteomics. Results: We identified 838 proteins in the intermediate filament fraction of cells. TGF-β1 treatment increased the proportion of vimentin in this fraction and the levels of 24 proteins. Variants of fibronectin showed the most pronounced increase (137-fold), followed by regulators of the cytoskeleton, cell motility, and division, such as the mRNA-splicing protein SON. TGF-β1 increased cell spreading and cell migration speed, and changed a positive correlation between cell migration speed and persistence to negative. ALD-R491 reversed these mesenchymal phenotypes to epithelial and the binding of RNA-binding proteins, including SON. Conclusions: These findings present many new interactors of intermediate filaments, describe how EMT and vimentin filament dynamics influence the intermediate filament interactome, and present ALD-R491 as a possible EMT-inhibitor. The observations support the hypothesis that the dynamic turnover of vimentin filaments and their interacting proteins govern mesenchymal cell migration, EMT, cell invasion, and cancer metastasis.

Vimentin at the core of wound healing

As a member of the large family of intermediate filaments (IFs), vimentin has emerged as a highly dynamic and versatile cytoskeletal protein involved in many key processes of wound healing. It is well established that vimentin is involved in epithelial-mesenchymal transition (EMT) during wound healing and metastasis, during which epithelial cells acquire more dynamic and motile characteristics. Moreover, vimentin participates in multiple cellular activities supporting growth, proliferation, migration, cell survival, and stress resilience. Here, we explore the role of vimentin at each phase of wound healing, with focus on how it integrates different signaling pathways and protects cells in the fluctuating and challenging environments that characterize a healing tissue.

Therapeutic targeting of vimentin by ALD-R491 impacts multiple pathogenic processes to attenuate acute and chronic colitis in mice

BACKGROUND

Vimentin, an intermediate filament protein, crucially contributes to the pathogenesis of inflammatory bowel disease (IBD) by interacting with genetic risk factors, facilitating pathogen infection, and modulating both innate and adaptive immune responses. This study aimed to demonstrate preclinical proof-of-concept for targeting vimentin therapeutically in IBD across diverse etiologies.

METHODS

The small molecule compound ALD-R491 was assessed for vimentin binding using microscale thermophoresis, off-target effects via Eurofins screening, and therapeutic effects in mice with dextran sulfate sodium (DSS)-induced acute colitis and in IL-10 KO with spontaneous colitis. Parameters measured included body weight, survival, disease activity, colon length, and histology. The study analyzed intestinal proinflammatory cytokines, Th17/Treg cells, and epithelial barrier molecules, along with gut microbiota profiling.

RESULTS

ALD-R491 specifically bound vimentin with a dissociation constant (KD) of 328 ± 12.66 nM and no off-target effects. In the DSS model, orally administered ALD-R491 exhibited dose-dependent therapeutic effects, superior to 5-ASA and Tofacitinib. In the IL-10 KO model, ALD-R491 significantly delayed colitis onset and progression, with near-zero disease activity index scores over a 15-week treatment. ALD-R491 consistently showed in both models a reduced proinflammatory cytokine expression, including TNF-α, IL-1β, IL-6, IL-17, IL-22, a rebalanced Th17/Treg axis by reducing RORγt while enhancing FoxP3 expression, and an improved epithelial barrier integrity by increasing intestinal expressions of Mucin-2, ZO-1 and Claudin5. The intestinal dysbiosis was restored with enriched presence of probiotics.

CONCLUSIONS

Targeting vimentin exhibits significant therapeutic effects on various facets of IBD pathogenesis, representing a compelling approach for the development of highly effective treatments in IBD.

Regulation of cellular contractile force, shape and migration of fibroblasts by oncogenes and Histone deacetylase 6

The capacity of cells to adhere to, exert forces upon and migrate through their surrounding environment governs tissue regeneration and cancer metastasis. The role of the physical contractile forces that cells exert in this process, and the underlying molecular mechanisms are not fully understood. We, therefore, aimed to clarify if the extracellular forces that cells exert on their environment and/or the intracellular forces that deform the cell nucleus, and the link between these forces, are defective in transformed and invasive fibroblasts, and to indicate the underlying molecular mechanism of control. Confocal, Epifluorescence and Traction force microscopy, followed by computational analysis, showed an increased maximum contractile force that cells apply on their environment and a decreased intracellular force on the cell nucleus in the invasive fibroblasts, as compared to normal control cells. Loss of HDAC6 activity by tubacin-treatment and siRNA-mediated HDAC6 knockdown also reversed the reduced size and more circular shape and defective migration of the transformed and invasive cells to normal. However, only tubacin-mediated, and not siRNA knockdown reversed the increased force of the invasive cells on their surrounding environment to normal, with no effects on nuclear forces. We observed that the forces on the environment and the nucleus were weakly positively correlated, with the exception of HDAC6 siRNA-treated cells, in which the correlation was weakly negative. The transformed and invasive fibroblasts showed an increased number and smaller cell-matrix adhesions than control, and neither tubacin-treatment, nor HDAC6 knockdown reversed this phenotype to normal, but instead increased it further. This highlights the possibility that the control of contractile force requires separate functions of HDAC6, than the control of cell adhesions, spreading and shape. These data are consistent with the possibility that defective force-transduction from the extracellular environment to the nucleus contributes to metastasis, via a mechanism that depends upon HDAC6. To our knowledge, our findings present the first correlation between the cellular forces that deforms the surrounding environment and the nucleus in fibroblasts, and it expands our understanding of how cells generate contractile forces that contribute to cell invasion and metastasis.