Vaimentin

Vimentin is a type III intermediate filament protein that constitutes a principal component of the cytoskeleton in many vertebrate cell types. In humans it is encoded by the VIM gene and is expressed broadly in mesenchymal cells.

Vimentin monomers assemble into coiled-coil dimers, tetramers, unit-length filaments and mature 10-nanometer intermediate filaments that extend throughout the cytoplasm. These filaments provide mechanical support, help maintain cell shape, and organize the cytoplasm by anchoring organelles such as the nucleus and mitochondria. Vimentin networks interact with other cytoskeletal systems, including actin filaments and microtubules, and are involved in vesicle trafficking and signaling.

Expression is high in fibroblasts, endothelial cells, leukocytes, and other mesenchymal cell types, and is typically low in epithelial cells; expression is upregulated during epithelial–mesenchymal transition and tissue remodeling. The protein is regulated by post-translational modifications, notably phosphorylation, ubiquitination, acetylation, and sumoylation, which alter filament assembly and disassembly during the cell cycle and in response to stress.

Clinical relevance: vimentin is widely used as a histological marker of mesenchymal cells and as an indicator of epithelial–mesenchymal transition in cancer. Increased vimentin expression is associated with enhanced migratory capacity and metastasis in various carcinomas. Vimentin can be detected in circulating tumor cells and is a target of research in cancer diagnostics and therapy. Autoantibodies to vimentin have been described in some autoimmune conditions.