The CBX8 Knockout HAP1 Polyclonal Cells product consists of a heterogeneous population of HAP1 cells in which the CBX8 gene has been disrupted by CRISPR/Cas9-mediated gene editing. This polyclonal knockout format yields a diverse spectrum of loss-of-function mutations, enabling robust functional studies without the clonal biases associated with single-cell-derived lines. The gene-edited cells are well-suited for investigating CBX8-dependent processes in a near-haploid human context, supporting gene-function analysis and epistatic interaction screens.
The HAP1 host cell line is a near-haploid, adherent, fibroblast-like cell originating from the KBM-7 chronic myeloid leukemia patient isolate. Its hematopoietic origin and leukemic background provide physiological relevance for studying chromatin regulators in blood cancers, while the near-haploid genome simplifies knockout generation and downstream genetic analyses. HAP1 cells are widely adopted in functional genomics, particularly for dissecting signaling pathways and transcriptional control in cancer.
CBX8 is a chromodomain-containing component of the Polycomb Repressive Complex 1 (PRC1) that specifically recognizes trimethylated histone H3 lysine 27 (H3K27me3), a repressive mark deposited by PRC2 (comprising EZH2, SUZ12, and EED). Upon binding H3K27me3, CBX8 facilitates PRC1 assembly through interactions with RING1A/B, BMI1, RYBP, and PHC proteins, directing the monoubiquitination of histone H2A at lysine 119 (H2AK119ub). This chromatin modification promotes compaction and transcriptional silencing of tumor suppressors including CDKN2A and CDKN2B, as well as cell cycle and Wnt pathway regulators such as CCND1, AXIN2, and SNAI1. CBX8 expression is itself controlled by upstream signals from EZH2, MYC, NF-kB, and miR-421, placing it at a critical junction of epigenetic and oncogenic regulation.
In the HAP1 leukemic background, CBX8 knockout permits direct interrogation of its role in maintaining the transformed state and evading senescence. Loss of CBX8 derepresses key targets like CDKN2A, predisposing the cells to growth arrest and senescence, thereby revealing epigenetic dependencies of CML and related malignancies. The polyclonal nature of the knockout population avoids clonal artifacts, offering a representative view of CBX8 depletion effects on proliferation, cell cycle progression, and chromatin architecture, and serves as a relevant model for drug target validation and PRC1 inhibitor screening.
Typical applications encompass functional genomics of PRC1-mediated repression, mechanistic studies of epigenetic silencing in breast cancer, hepatocellular carcinoma, and lymphomas, and dissection of cellular senescence pathways. Researchers can quantify changes in target gene expression by RT-qPCR (e.g., CDKN2A, CCND1), assess PRC1 and H3K27me3 chromatin occupancy via ChIP-qPCR, and measure proliferation (MTS, EdU), senescence (??-galactosidase staining), and cell cycle distribution by flow cytometry. The cells are also suitable for co-immunoprecipitation of PRC1 complexes and global transcriptomic profiling by RNA-seq. For additional information or technical support, please contact Ascent Research.
