The HRNR Knockout HAP1 Polyclonal Cells are a polyclonal knockout population generated via CRISPR/Cas9-mediated disruption of the hornerin (HRNR) gene in the HAP1 cell line, creating a loss-of-function model for studying cornified envelope biology.
HAP1 is a near-haploid human cell line derived from the KBM-7 chronic myeloid leukemia line, renowned for its utility in near-haploid genetic screens and functional genomics studies due to its stable haploid karyotype across most chromosomes. Although these cells do not naturally undergo keratinocyte differentiation, their simplified genetic landscape offers a clean system to investigate HRNR function when combined with the introduction of epidermal-specific proteins or differentiation-inducing signals.
Hornerin, a member of the fused-type S100 family, is a major structural protein of the cornified envelope that is incorporated during keratinocyte terminal differentiation. Its expression is induced by calcium and regulated by transcription factors p63 and ZNF750, with modulation by EGFR, vitamin D, and cytokines such as IL-17 and TNF-??. HRNR is crosslinked by transglutaminases TGM1 and TGM3 and interacts with loricrin, involucrin, and filaggrin to fortify the epidermal barrier. Loss of HRNR function disrupts envelope assembly and filaggrin processing, contributing to barrier defects seen in atopic dermatitis and psoriasis.
This polyclonal knockout population enables comprehensive characterization of HRNR??s molecular behavior in isolation. By eliminating endogenous hornerin, researchers can map direct protein?Cprotein interactions, examine post-translational modifications, and assess the impact of disease-associated mutations via complementation assays. The pool format ensures broad mutation coverage and avoids single-clone artifacts, making it ideal for robust, reproducible functional analyses and chemical library screening to identify small-molecule modulators of cornified envelope assembly.
Typical experimental workflows include immunofluorescence to monitor localization of envelope proteins like loricrin and involucrin after co-expression, quantitative RT-PCR to measure transcript levels of differentiation markers such as filaggrin, and western blotting for detecting HRNR and its crosslinked forms. Barrier function can be evaluated by transepithelial electrical resistance (TEER) in transwell culture models, while calcium-induced differentiation assays??performed after transient transfection of key transcription factors??elucidate regulatory mechanisms. These cells accelerate drug discovery for dermatoses including atopic dermatitis, psoriasis, and ichthyosis vulgaris. For technical support, please reach out to Ascent Research.
