Epiplakin is a large cytoplasmic protein that is encoded by the EPPK1 gene in humans. Epiplakin was first identified as an autoantigen. [4]
Epiplakin is a large cytoplasmic protein that is encoded by the EPPK1 gene in humans. Epiplakin was first identified as an autoantigen. [4]
The initial discovery of Epiplakin came from a patient who had a rare autoimmune skin disease that caused blistering at the junction of the epidermis and dermis. After closer examination, scientists saw that the patient's blood had contained autoantibodies that reacted with an unknown protein in the epidermis. The unknown protein was almost entirely made of repeated plakin domains. [4]
The peptide recognition domain of epiplakin is able to bind to keratins in vitro; however, in cells the epiplakin associates with keratin intermediate filaments networks only under conditions in which cellular stress is absent. Otherwise, epiplakin remains universally cytoplasmic and not bound to the intermediate filaments.
Human epiplakin contains 13 peptide recognition domains (PRDs) and have a total size of about 725 kDa. Unlike plakins, they lack an N-terminal actin-binding domain. [5] [4]
Epiplakin's role in maintaining keratin intermediate filament organization suggests that dysregulation of epiplakin expression or function may contribute to epithelial fragility or altered wound-healing responses, as indicated by accelerated wound closure observed in epiplakin-depleted corneal epithelial cells.
Scientists have examined EPPK1 expression in multiple types/forms of cancers (bladder, lung, colon, etc.). Various studies show that altered Epiplakin levels in tumor tissues show correlation with tumor progression pathways. [6]