Cytoskeleton remodeling Keratin filaments

Keratin filaments

Cytoskeleton in most eukaryotic cells consists of three distinct, yet interconnected,filament systems: Actin filaments, Microtubules and intermediate filaments.Cell assembly is integrated by the network of intermediate filaments (IFs) and by theirinteractions with other cytoskeleton structural elements defining cytoarchitecture andcytodynamics.

IF network is critically involved in cell shape control and imparts intracellularmechanical strength. The family of IF proteins has five sub-families. Four of thesub-families are localized in the cytoplasm, whereas the fifth sub-family is found in thenucleus. Expression patterns of cytoplasmic IFs are cell- and tissue-type specific.

 The main IF protein is found in epithelial cells is Keratin and in fibroblastsit is Vimentin. Keratin IFs are obligate co-polymers of acidic and basiccytokeratins [1], [2].

IF networks are cross-linked by special binding proteins, e.g., Plectin,BPAG1, Desmoplakin, Envoplakin, Periplakin,Epiplakin, Trichoplein and Plakophilins [3], [4], [5], [6]. These proteins maintain cell and tissueintegrity by coordinated interconnection of three distinct cytoskeletal filament systems,and anchoring them to membrane complexes.

Assembly, disassembly and subcellular organization of IFs is regulated by kinases,e.g., by Mitogen-activated protein kinases 8-10 ( JNK(MAPK8-10) ) and Celldivision cycle 2 ( CDK1 ) [7], [8].

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