Keratins: Guardians of the liver

The Cytoskeleton Plays an Important Role in Human Disease T he three major filament cytoskeletal protein networks that maintain cellular structure and integrity in eukaryotic cells are actin microfilaments, tubulin microtubules, and the large family of tissue-specific intermediate filament (IF) proteins. These cytoskeletal proteins participate in a wide range of important cellular functions including cell division, motility, maintenance of cellular mechanical integrity, stress responses, and vesicle transport. Accumulating evidence indicates that these 3 cytoskeletal families and/or their associated proteins play an important role in human disease. For example, actin mutations cause cardiac and noncardiac myopathies 2 and although tubulin mutations have not been described, the microtubule-associated protein tau is involved in Parkinson's disease. In functional terms, IF proteins are the least understood of the 3 cytoskeletal families, yet they are associated with a broad range of human diseases that reflect their diversity and tissue distribution. 5]