Health / Medical Topics |
Keratinocyte Differentiation Pathway
The epidermis, which provides a protective barrier that undergoes a constant renewal, is a multi-layered tissue with the proliferating cells located in the basal layer. As cells leave the basal layer they undergo significant differentiation and biochemical and morphological remodeling. The final differentiation results in the formation of corneocytes. In vitro keratinocytes mimic this process. Several genes mark keratinocyte specific differentiation. Among the most frequently tracked markers are transglutaminase, cystatin and involucrin. Keratinocyte differentiation studies have identified and provided significant detail regarding the involvement of three of the 4 major MAP kinase pathways from several diverse stimuli such as EGF, FAS, TNF and calcium influx. The keratinocyte differentiation cascades also provide for detailed study of the functions of individual PKC isoforms and it is interesting to note the contrasting functions of the PKC isoforms in this process. In recent studies it has been determined that the cPKC (conventional/classical Protein Kinase C) isoforms, which are calcium-, phospholipid-, and diacylglycerol-dependent are inhibitory where as the nPKC (novel Protein Kinase C) isoforms which are calcium independent are stimulatory for keratinocyte differentiation markers. (NCI Thesaurus/BIOCARTA)