Filaggrins are an important class of the intermediate filament-associated proteins which interact with keratin intermediate filaments (IFs) of terminally differentiating mammalian epidermis. A precursor molecule of filaggrin, profilaggrin, accumulates in the epidermis as keratohyalin granules which, in mouse, is phosphorylated and incapable of interaction with IFs. At the time of terminal differentiation, the precursor is proteolytically processed by excision of the linker to individual filaggrin molecules which are then able to interact with keratin IFs. Filaggrins exhibit wide species variations and their aberrant expression has been reported in a number of human keratinizing disorders such as parakeratosis, psoriasis and molluscum contagiosum. Filaggrin also appears to be a target molecule for rheumatoid arthritis-specific auto-antibodies in humans.
Image: Filaggrin staining of paraffin-embedded normal Human Skin Tissue. Note intense cytoplasmic staining of terminally differentiated keratinocytes.
