The E2F4 Knockout K-562 Polyclonal Cells product provides a CRISPR/Cas9-mediated gene-disrupted pool of K-562 human chronic myeloid leukemia cells, featuring targeted loss of E2F4 expression. This polyclonal knockout cell population is generated through transient introduction of Cas9 and a guide RNA specifically designed to disrupt the E2F4 coding sequence, resulting in a heterogeneous mixture of edited alleles. The product serves as a versatile loss-of-function model for investigating E2F4-dependent transcriptional repression, cell cycle regulation, and leukemia biology without the need for single-cell cloning. Researchers can employ this knockout pool directly in functional experiments, enabling robust comparisons with wild-type K-562 controls.
The host K-562 cell line originates from the pleural effusion of a 53-year-old female patient with BCR-ABL-positive chronic myeloid leukemia in blast crisis. K-562 cells represent a widely utilized pluripotent hematopoietic progenitor model that displays erythroid, granulocytic, and monocytic differentiation potential. The presence of the constitutively active BCR-ABL tyrosine kinase drives multiple oncogenic signaling cascades, including the PI3K/AKT and RAS/RAF/MEK pathways, which converge on the cell cycle machinery. This genetic background establishes a disease-relevant context for studying the interplay between BCR-ABL signaling and transcriptional regulators like E2F4.
E2F4 functions as a key transcriptional repressor that controls the G1/S transition by binding to E2F-responsive promoters and recruiting co-repressor complexes through its association with pocket proteins p130 (RBL2) and p107 (RBL1). These complexes further involve histone deacetylases such as HDAC1 and the SIN3A scaffold, establishing a repressive chromatin environment at target genes. Under proliferative conditions, CDK4/6-cyclin D complexes phosphorylate pocket proteins, causing the release of E2F4 and subsequent derepression of genes critical for DNA replication, including CCNE1 (cyclin E), CCNA2 (cyclin A), DHFR, TK1, PCNA, and CDC6. Upstream signals from the TGF-?? receptor and PIK3CA/AKT axis modulate E2F4 activity by influencing CDK4/6-cyclin D assembly and pocket protein phosphorylation status.
In the K-562 model, BCR-ABL signaling hyperactivates CDK4/6, leading to sustained pocket protein phosphorylation and persistent E2F4 inactivation. This disruption of the E2F4-mediated transcriptional repression program is thought to contribute to uncontrolled cell cycle progression and the differentiation block characteristic of CML blast crisis. The E2F4 knockout polyclonal cells therefore provide a powerful tool to examine how the loss of this repressor further exacerbates proliferation or alters differentiation capacity in a BCR-ABL-dependent context. By comparing the knockout population to parental K-562, researchers can dissect E2F4-specific contributions to cell cycle exit, senescence induction, or response to differentiation cues.
Typical applications encompass cell cycle profiling by flow cytometry, monitoring DNA synthesis via BrdU incorporation, and assessing proliferation with MTT or similar metabolic assays. Gene expression changes can be quantified by RT-qPCR for E2F4 targets (e.g., CCNE1, PCNA) and confirmed by western blotting for E2F4, p130, and phosphorylated forms of pocket proteins. In drug response studies, the knockout cells enable investigation of altered sensitivity to BCR-ABL inhibitors like imatinib or to CDK4/6 inhibitors. The polyclonal nature of the product ensures that clonal selection artifacts are minimized, making it especially suitable for pooled functional screens and bulk multi-omics analyses. For additional details or assistance, please contact Ascent Research.
