The role of the OVOL1-OVOL2 axis in normal and diseased human skin.

OVOLs (OVO-like proteins) are ubiquitously conserved genes encoding a C2 H2 zinc finger transcription factor in mammals. Functional studies on OVOL1 and OVOL2 using knockout mice have suggested that these genes play a pivotal role in the development of epithelial tissues arising from germ cells; however, the role of the OVOL1-OVOL2 axis in normal and diseased tissues remains unclear. This review highlights recent advances in understanding how the OVOL1-OVOL2 axis modulates cell differentiation and proliferation in human keratinocytes, hair follicles, and benign or malignant skin tumors including squamous cell carcinoma and malignant melanoma. Furthermore, OVOL1 has been shown to be involved in the expression of skin barrier proteins including filaggrin (FLG), and its mutation or dysfunction leads to the development of atopic dermatitis (AD). OVOL1 has also been identified as a susceptibility gene for AD by genome-wide association studies, in addition to FLG. Therefore, we discuss the relationship between OVOL1 and FLG in the development of AD.