Keratin 5 (KRT5)

Keratin 5 is a type II intermediate filament protein encoded by the KRT5 gene, primarily expressed in basal keratinocytes of the epidermis and stratified epithelia, where it dimerizes with keratin 14 to form cytoskeletal networks that provide mechanical strength, resiliency, and anchorage to desmosomes and hemidesmosomes. This structural role is essential for maintaining skin barrier integrity against friction and stress, as well as facilitating melanosome transport from melanocytes to keratinocytes for normal pigmentation. Mutations in KRT5, often missense variants in hotspot regions of the central rod domain, cause epidermolysis bullosa simplex (EBS), a blistering skin disorder ranging from mild localized forms to severe Dowling-Meara types due to disrupted filament assembly and cytoskeletal integrity. In cancer, elevated KRT5 expression marks basal-like breast cancers (especially BRCA1-associated), squamous lung carcinomas, and mesothelioma, serving as a prognostic biomarker for aggressive phenotypes and aiding differential diagnosis, such as distinguishing mesothelioma from adenocarcinoma. Despite its diagnostic utility via CK5/6 immunohistochemistry, KRT5 is not a direct therapeutic target, with no approved drugs modulating it; instead, it informs patient stratification in epithelial malignancies.

Other names

CK5K5EBS2DDD1DDDKRT5A