Krt24, encoding keratin 24, is a cytoskeletal protein crucial for forming intermediate filaments, providing mechanical stability [2]. It has been associated with various biological processes and is expressed in specific cell types such as outer bulge (OB) hair follicle stem cells (HFSCs), corneal epithelium, and amnion epithelium [1,3,4].

A study generated the Krt24-CreERT2 mouse line. When crossed with reporter lines, it enabled specific labeling or ablation of Krt24+ cells. Lineage tracing showed that Krt24+ cells differentiated into the outer root sheath during the anagen phase. Ablation of Krt24+ cells significantly delayed anagen initiation, and continuous depletion led to substantial mortality after ionizing irradiation. Also, ionizing radiation triggered expansion of Krt24+ cells while maintaining hair follicle homeostasis [1]. In breast cancer, high Krt24 expression at both transcriptomic and protein levels was associated with poor prognosis features and shorter survival in chemotherapy-treated patients [2].

In conclusion, Krt24 is essential for hair follicle development and damage repair as shown by the Krt24-CreERT2 mouse model [1]. Its abnormal expression is linked to poor prognosis in breast cancer, highlighting its potential as a prognostic biomarker and therapeutic target in this disease [2].

References:

1. Wang, Jiao, Qiu, Yifei, Zhu, Yansheng, Zhou, Gangqiao, Cao, Pengbo. 2025. Generation of the Krt24-CreERT2 Mouse Line Targeting Outer Bulge Hair Follicle Cells. In International journal of molecular sciences, 26, . doi:10.3390/ijms26073165. https://pubmed.ncbi.nlm.nih.gov/40243932/

2. Kariri, Yousif A, Alsaleem, Mansour, Kariri, Taher A, Asad, Mohammed, Rakha, Emad A. 2025. Keratin 24 (KRT 24) Predicts Poor Prognosis in Breast Cancer. In Pathobiology : journal of immunopathology, molecular and cellular biology, , 1-22. doi:10.1159/000546022. https://pubmed.ncbi.nlm.nih.gov/40254011/

3. Ehrlich, Florian, Laggner, Maria, Langbein, Lutz, Tschachler, Erwin, Eckhart, Leopold. 2019. Comparative genomics suggests loss of keratin K24 in three evolutionary lineages of mammals. In Scientific reports, 9, 10924. doi:10.1038/s41598-019-47422-y. https://pubmed.ncbi.nlm.nih.gov/31358806/

4. Zhu, Yujuan, Wang, Hui, Yin, Fangchao, Gao, Dong, Qin, Jianhua. . Amnion-on-a-chip: modeling human amniotic development in mid-gestation from pluripotent stem cells. In Lab on a chip, 20, 3258-3268. doi:10.1039/d0lc00268b. https://pubmed.ncbi.nlm.nih.gov/32749421/