KRT17

Keratin 17 (KRT17) is a type I intermediate filament protein encoded by the human KRT17 gene. It forms part of the cytoskeletal network in stratified epithelia by pairing with type II keratins, such as KRT6A and KRT16, to assemble keratin intermediate filaments that support cellular structure and resilience.

Expression of KRT17 is notable in nail beds, hair follicles (notably the outer root sheath), sebaceous glands, and select hyperproliferative epithelia. Its expression is often upregulated during wound healing and in certain skin diseases, and it can participate in regulating cell growth and migration alongside other keratins.

Pathogenic variants in KRT17 cause Pachyonychia congenita type 4 (PC-4), a rare inherited keratinization disorder. PC-4 features include nail dystrophy, palmoplantar keratoderma, oral leukoplakia, and follicular keratoderma, with autosomal dominant inheritance and variable expressivity.

In pathology and oncology, KRT17 serves as a diagnostic and research marker. It is sometimes overexpressed in a subset of squamous cell carcinomas and other tumors, and immunohistochemical detection of KRT17 can aid in tumor characterization and in studies of epithelial differentiation and proliferation.

Structurally, keratin 17 is approximately 430 amino acids in length and belongs to the broader keratin family, which comprises type I keratins that pair with type II keratins to form the cytoskeletal filaments essential for epithelial integrity.