The HSP90AB1 Knockout HAP1 Polyclonal Cells represent a CRISPR/Cas9-edited polyclonal cell population designed to disrupt the HSP90AB1 gene, which encodes the constitutively active molecular chaperone HSP90??. This loss-of-function model eliminates functional HSP90??, enabling systematic investigation of its essential roles in client protein stabilization and signal transduction. The polyclonal format provides a heterogeneous knockout population suitable for pooled functional assays without clonal isolation. Researchers can employ this cellular tool to dissect HSP90AB1-dependent pathways and evaluate the consequences of chaperone impairment in a near-haploid genetic background.
The host HAP1 cell line is a near-haploid, fibroblast-like cancer model derived from a patient with chronic myeloid leukemia (CML). HAP1 cells are adherent, express the BCR-ABL1 fusion oncogene, and maintain a stable near-haploid karyotype, which simplifies genetic analysis and reduces redundancy in loss-of-function studies. Originally derived from KBM-7 cells, this line has become a workhorse for genetic screens, drug target validation, and signaling research due to its ease of manipulation and robust growth in standard culture conditions.
HSP90?? functions as a central hub in the chaperone network, forming dynamic complexes with co-chaperones including CDC37, AHA1, p23 (PTGES3), HSP70 (HSPA1A), Hop (STIP1), and immunophilins such as FKBP4 and FKBP5. It is activated by heat stress and the transcription factor HSF1, and regulated by post-translational modifications like CK2-mediated phosphorylation. HSP90?? stabilizes a diverse array of client proteins, notably the kinases AKT1, RAF1, and CDK4, the glucocorticoid receptor NR3C1, the tumor suppressor p53 (TP53), and the growth factor receptor EGFR. By maintaining the folding and activity of these clients, HSP90?? supports pro-survival signaling through the PI3K/AKT and MAPK/ERK cascades and modulates cell cycle progression and apoptosis.
In the HAP1 background, which harbors the oncogenic BCR-ABL1 fusion, HSP90AB1 knockout has profound implications. BCR-ABL1 constitutively activates downstream effectors including AKT1 and RAF1, both of which are HSP90 clients. Disruption of HSP90?? is expected to destabilize these kinases, thereby attenuating AKT/mTOR and RAF/MEK/ERK signaling, reducing proliferation, and sensitizing cells to apoptotic cues. This model therefore recapitulates the vulnerabilities observed in CML and other cancers reliant on HSP90 chaperone function, making it a relevant platform for studying oncogene addiction and resistance mechanisms.
Typical research applications encompass functional genomics screens to catalogue HSP90-dependent client profiles, validation of small-molecule HSP90 inhibitors in dose-response viability assays, and synthetic lethality studies that exploit chaperone dependency in cancer. Researchers can assess client protein levels by western blotting, quantify transcript changes via RT-qPCR, evaluate apoptosis through Annexin V staining, and map protein interactions by co-immunoprecipitation. Phospho-protein arrays further enable characterization of signaling network rewiring upon HSP90AB1 loss. This knockout model serves as a versatile tool for dissecting chaperone biology and identifying therapeutic targets. For further information or custom inquiries, please contact Ascent Research.
