The ISG15 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population with targeted disruption of ISG15 in the HAP1 cell line. This product provides a genetically defined loss-of-function model for studying ISG15 biology in innate immunity and cancer. The polyclonal format maintains near-haploid genetic simplicity while avoiding clonal selection biases, facilitating robust population-level phenotypic analyses.
HAP1 is a near-haploid human cell line derived from the KBM-7 chronic myeloid leukemia (CML) line. Its haploid genetic complement allows efficient gene targeting and clear genotype-phenotype correlations, making it a preferred host for CRISPR-based knockout screens. HAP1 cells retain myeloid signaling capacity, including robust responsiveness to type I interferons, which is essential for studying interferon-inducible genes such as ISG15.
ISG15 encodes a ubiquitin-like protein transcriptionally induced by IFN-??/?? via the JAK-STAT pathway, with STAT1, STAT2, and IRF9 forming the ISGF3 complex. ISG15 is conjugated to target proteins through an enzymatic cascade of UBE1L (E1), UBE2L6 (E2), and HERC5 (E3), a modification known as ISGylation that regulates antiviral effectors like PKR and MxA and modulates IRF3 and STAT1 signaling. DeISGylation is mediated by USP18. Additionally, ISG15 functions as an extracellular cytokine by engaging the CD11a/CD18 (ITGAL/ITGB2) integrin, enhancing NK cell and T cell responses.
In the HAP1 near-haploid model, ISG15 disruption enables clear separation of its conjugation-dependent and cytokine functions. The CML origin provides a relevant myeloid context for investigating ISG15??s roles in leukemia immunology and interferon signaling. Because HAP1 cells robustly induce ISG15 upon IFN stimulation, this knockout system is ideal for dissecting ISG15-dependent feedforward and feedback loops within the antiviral response.
This knockout model supports diverse experimental approaches, including viral infection assays to assess innate antiviral immunity, western blotting and co-immunoprecipitation to profile ISGylation substrates and dynamics, and RT-qPCR to quantify interferon-stimulated gene expression. Flow cytometry and ELISA can be used to measure secreted ISG15 effects on immune cell activation. The polyclonal population is a versatile tool for exploring ISG15 biology in host defense, autoimmune disease, and cancer immunology. For further information, please contact Ascent Research.
