The DNAJB1 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population of human HAP1 near-haploid myeloid leukemia cells with targeted disruption of the DNAJB1 gene. This loss-of-function model provides constitutive abrogation of DNAJB1-encoded Hsp40 co-chaperone activity, enabling studies of proteostasis and stress response in a genetically tractable background. The polyclonal format avoids clonal selection artifacts and reflects a broad spectrum of edits.
The HAP1 host cell line is a near-haploid derivative of the KBM-7 chronic myeloid leukemia line. Its haploid karyotype simplifies CRISPR-based gene disruption by requiring single-allele targeting, and it retains key signaling and stress pathways. This background is widely used for functional genomic screens and cellular stress studies, providing a homogeneous context for examining chaperone biology and proteolytic networks.
DNAJB1 encodes a J-domain cochaperone that functions downstream of the HSF1 transcription factor under heat shock and cellular stress. It directly interacts with HSPA1A (Hsp70) and STIP1 to stimulate Hsp70 ATP hydrolysis, driving substrate folding and trafficking. DNAJB1 also partners with STUB1 (CHIP) for ubiquitin-mediated degradation of misfolded proteins. Core pathway members include HSPA1A, HSF1, BAG family cochaperones, and STUB1. Loss of DNAJB1 disrupts Hsp70 client processing, sensitizing cells to proteotoxic stress and impairing protein quality control.
In the HAP1 near-haploid system, DNAJB1 knockout impairs cellular stress resilience, increases susceptibility to heat shock and Hsp90 inhibitor treatment, and leads to accumulation of insoluble protein aggregates. This model is directly relevant to fibrolamellar hepatocellular carcinoma, where DNAJB1 fusions are a hallmark, and to neurodegenerative diseases involving protein misfolding. The haploid background enhances quantitative genetic interaction studies and drug sensitization screens, offering a powerful platform for proteostasis research.
Researchers can employ these polyclonal knockout cells for Western blotting of DNAJB1 and client proteins, RT-qPCR analysis of stress-induced transcription, cell viability assays under heat shock, and proteotoxicity assessment with aggregation reporters. Additional applications include Hsp90 inhibitor sensitivity profiling, immunoprecipitation of Hsp70 complexes, and immunofluorescence detection of protein aggregates. These assays support studies in cancer biology, neurodegeneration, and chaperone pharmacology. For further details, contact Ascent Research.
