vimentin

Vimentin is a type III intermediate filament protein that forms the cytoskeletal network of cells of mesenchymal origin. It is encoded by the VIM gene and widely used as a marker of mesenchymal cells. The vimentin network provides mechanical support, helps maintain cell shape, and coordinates the distribution of organelles. It interacts with other cytoskeletal systems, notably actin filaments and microtubules, to shape cell architecture and dynamics.

Vimentin monomers have a central coiled-coil alpha-helical rod domain flanked by nonhelical head and tail regions. Two monomers form a dimer, dimers assemble into tetramers, and tetramers assemble into unit-length filaments that mature into the cytoplasmic intermediate filament network. Filament organization is dynamic and responds to cellular signals.

Expression is prominent in fibroblasts, endothelial cells, and leukocytes, and is a hallmark of mesenchymal cells. Vimentin is upregulated during epithelial-to-mesenchymal transition (EMT) and in processes such as development, wound healing, and cancer metastasis. Functionally, it supports cell migration and invasion, contributes to mechanical resilience, and participates in signaling and organelle dynamics, including mitochondrial positioning and ER organization.

Post-translational modifications regulate filament assembly. Phosphorylation of serine residues during mitosis by kinases such as CDK1 induces disassembly, allowing chromosome segregation; dephosphorylation promotes reassembly in daughter cells. Additional modifications, including acetylation and glycosylation, can modulate filament properties and interactions.

Clinical and research relevance: Vimentin is widely used in histology as a marker of cells of mesenchymal origin and EMT status in tumors. Aberrant vimentin expression can accompany aggressive cancer phenotypes, and anti-vimentin antibodies are used to identify mesenchymal cells and certain sarcomas.