The FOSL1 Knockout HaCaT Cell Line is a CRISPR/Cas9-edited human knockout cell line designed to abrogate expression of the Fra-1 transcription factor through targeted disruption of the FOSL1 locus. This model provides a stable loss-of-function system in a keratinocyte background, enabling dissection of AP-1-dependent gene regulatory networks without the confounding effects of pharmacological inhibition.
The parental HaCaT cell line is a spontaneously immortalized, aneuploid, non-tumorigenic human keratinocyte line derived from adult skin. HaCaT cells retain the capacity for epidermal differentiation and are widely used to study barrier formation, wound healing, and cutaneous homeostasis. Their responsiveness to growth factors and cytokines makes them a robust platform for investigating skin biology and disease-relevant signaling.
FOSL1 (Fra-1) is a core component of the AP-1 transcription factor complex, heterodimerizing with JUN family members (c-Jun, JunB, JunD) and ATF proteins. Fra-1 is activated by ERK1/2 (MAPK3/1) downstream of EGFR in response to EGF or TGF-??, and its transcription is controlled by SRF/ELK1 and Wnt/??-catenin?CTCF/LEF. Once activated, Fra-1?CAP-1 dimers drive expression of matrix metalloproteinases (MMP1, MMP9), pro-migratory factors (ITGB3, CYR61), EMT regulators (ZEB1, SNAI1, VIM, CDH2), and the cell-cycle gene CCND1. Fra-1 interacts with p300/CBP and SMAD3, integrating TGF-?? and chromatin-remodeling signals. Knockout of FOSL1 eliminates this transcriptional hub, disarming AP-1 programs for proliferation, invasion, and survival.
In the HaCaT keratinocyte context, loss of FOSL1 profoundly alters cellular responses to mitogenic and pro-inflammatory stimuli. The absence of Fra-1 disrupts the orchestration of genes required for re-epithelialization and ECM remodeling during wound healing, impairs migration and invasiveness in scratch and Transwell assays, and attenuates the expression of EMT-associated markers. Because Fra-1 is frequently overexpressed in cutaneous squamous cell carcinoma and other epithelial cancers, the FOSL1 Knockout HaCaT Cell Line serves as a critical tool to distinguish Fra-1-dependent from Fra-1-independent effects in hyperproliferative and invasive phenotypes. It also enables the study of AP-1 involvement in inflammatory skin diseases such as psoriasis, where Fra-1 potentiates cytokine-driven keratinocyte hyperproliferation.
This knockout line is suited for studying AP-1-driven tumor invasion, EMT, and wound healing. It supports drug screening against AP-1/MAPK/ERK targets, dermatological toxicity testing, and transcriptomic profiling of the Fra-1 network. Assays include immunoblotting for Fra-1/MMPs/EMT markers, RT-qPCR, scratch/Transwell migration, immunofluorescence for keratins, AP-1 luciferase reporter, RNA-seq, and apoptosis analysis. For more details, contact Ascent Research.
