The BST2 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population that disrupts the BST2 gene in the near-haploid HAP1 cell line. This heterogeneous pool provides a loss-of-function model for studying BST2 (tetherin) function without clonal selection bias, enabling investigation of viral restriction, interferon signaling, and NF-??B modulation.
HAP1 is a human near-haploid cell line derived from the KBM-7 chronic myeloid leukemia patient. Its haploid nature simplifies genetic loss-of-function studies, while its leukemic origin provides a hematologic context for innate immunity and cancer research.
BST2 (also known as tetherin) is a type II transmembrane protein that acts as an interferon-inducible host restriction factor. It impedes viral release by physically cross-linking budding virions to the cell surface, a process that requires BST2 homodimerization. Its expression is robustly induced by type I (IFN-??/??) and type II (IFN-??) interferons through the canonical JAK-STAT pathway, where ligand-bound IFNAR activates JAK1 and TYK2, leading to phosphorylation of STAT1 and STAT2, which dimerize and recruit IRF9 to form the ISGF3 transcription complex. Additional regulators include LPS, IL-1, and TNF. Beyond virus tethering, BST2 functions as an innate immune signaling adaptor by engaging the TRAF2-TAK1-IKK axis, culminating in NF-??B activation and transcription of pro-inflammatory cytokines and pro-apoptotic factors. BST2 also interacts with clathrin, linking it to endocytic trafficking. To counteract BST2, diverse viruses have evolved antagonists: HIV-1 Vpu targets BST2 for degradation, while Ebola VP40 and KSHV K5 also subvert its function.
The HAP1 knockout model enables investigation of BST2 in a leukemic, near-haploid setting, where its tumor-suppressive and antiviral activities can be studied without interference from wild-type alleles. This system is particularly valuable for examining how BST2 loss impacts the release of HIV-1, Ebola, and KSHV, as well as for dissecting BST2’s role in NF-??B-driven survival signaling relevant to multiple myeloma and other hematologic malignancies. The hematopoietic lineage authenticity of HAP1 cells further supports physiologically relevant interferon and inflammatory responses.
Researchers can employ these polyclonal knockout cells in a wide array of assays: HIV-1 release assays and viral tethering assays to quantify restriction, co-expression with Vpu or other antagonists to study viral evasion, interferon stimulation coupled with RT-qPCR or Western blotting to monitor JAK-STAT pathway activation, NF-??B luciferase reporter assays to probe TRAF2-TAK1 signaling, co-immunoprecipitation for BST2 interaction partners, and electron microscopy to visualize virion tethering. This model also facilitates high-throughput screening of modulators of BST2-mediated restriction and signaling. For further inquiries, please contact Ascent Research.
