Keratinocytic

Keratinocytic is an adjective relating to keratinocytes, the predominant cell type of the epidermis. Keratinocytes are specialized epithelial cells that originate from stem cells in the basal layer of the epidermis and migrate outward as they differentiate, forming the multilayered epidermal structure that provides a protective barrier.

Keratinocytes synthesize keratin proteins, creating intermediate filaments that give the cells mechanical resilience. They differentiate through the epidermal layers—basal, spinous, granular, and cornified—expressing different keratins at each stage (for example, KRT5 and KRT14 in basal cells, KRT1 and KRT10 in suprabasal cells). In the granular layer, they produce proteins such as filaggrin and loricrin, and cells in the outermost cornified layer become enucleated corneocytes filled with keratin, forming the stratum corneum.

Beyond their structural role, keratinocytes contribute to the skin’s barrier function by forming desmosomal and tight junction networks and by producing lipids that help prevent transepidermal water loss. They participate in wound healing by proliferating and migrating to close injuries, and they engage in immune signaling by secreting cytokines and chemokines in response to injury or infection. Keratinocytes interact with other skin cells, including melanocytes and Langerhans cells, influencing pigmentation and immune responses.

Clinical relevance includes keratinopathies caused by mutations in keratin genes (such as epidermolysis bullosa simplex due to KRT5/14 mutations or pachyonychia congenita involving KRT6A/16/17). Dysregulated keratinocyte proliferation and differentiation are notable in inflammatory skin diseases like psoriasis, highlighting the importance of keratinocytic biology in skin health and disease.