The ATF6B Knockout HAP1 Polyclonal Cells are a heterogeneous population of human HAP1 chronic myeloid leukemia (CML) cells with CRISPR/Cas9-mediated disruption of the ATF6B gene. This polyclonal knockout pool provides a loss-of-function model for studying ATF6B-dependent pathways without single-cell cloning. The near-haploid HAP1 background enables straightforward genotype-phenotype correlation, facilitating high-throughput screening for UPR and ER stress research.
HAP1 cells, derived from KBM-7 CML cells, possess a near-haploid karyotype that simplifies gene-editing and genetic screens. Their haploid nature allows unambiguous linkage of phenotypes to single-allele disruption, aiding pathway dissection. Originating from blast crisis CML, HAP1 cells retain core stress response pathways, including the UPR, making them relevant for cancer and ER stress studies. This ATF6B knockout polyclonal population leverages haploid genetics for dissecting ER stress signaling in a disease-associated context.
ATF6B encodes a bZIP transcription factor that is an ER stress sensor: upon unfolded protein accumulation, it is cleaved by S1P (MBTPS1) and S2P (MBTPS2) proteases, releasing an active N-terminal fragment that translocates to the nucleus. There, it upregulates chaperones (BiP/GRP78, GRP94) and ER-associated degradation (ERAD) components. ATF6B cooperates with ATF6??, IRE1??, and PERK, and converges on XBP1 and CHOP to modulate adaptive and apoptotic outputs. This network determines cell fate under ER stress, with ATF6B participating in both prosurvival and proapoptotic signaling.
Disrupting ATF6B in haploid HAP1 cells eliminates confounding effects of paralog redundancy, enabling precise evaluation of ATF6B’s role in UPR. The polyclonal knockout population reveals altered transcription of ER stress targets when exposed to tunicamycin or thapsigargin. ATF6B loss may expose reliance on parallel UPR branches, offering insights into synthetic vulnerabilities in cancers dependent on ER stress pathways. The haploid background ensures direct attribution of phenotypes to ATF6B deficiency, supporting mechanistic studies in stress adaptation and apoptosis.
This model suits functional genomics screens for UPR interactors, small-molecule validation targeting ER stress sensors, and investigation of ATF6B in cancer cell stress. Assays include RT-qPCR for BiP and CHOP, immunoblotting for ATF6B cleavage, ERSE-driven reporter assays, RNA-seq transcriptomics, and cell viability tests with proteasome inhibitors. The polyclonal design enables screening applications without clonal bottlenecks. For further information, please contact Ascent Research.
