The HEXIM2 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population generated from the HAP1 human near-haploid hematopoietic cell line. This loss-of-function model features disruption of the HEXIM2 gene, which encodes a key negative regulator of transcription elongation. The polyclonal format provides a heterogeneous pool of edited cells, avoiding clonal selection bias and enabling robust functional studies of HEXIM2 in a near?haploid genetic background.
The host HAP1 cell line is derived from the KBM-7 subline, originally isolated from a 39-year-old male with chronic myeloid leukemia (CML) in blast crisis. HAP1 cells are near-haploid and of hematopoietic origin, making them an ideal platform for genetic perturbation and functional genomics. Their growth characteristics and amenability to diverse assays, including high?throughput screening, support widespread use in cancer biology and signal transduction research.
HEXIM2 binds the 7SK small nuclear RNA and assembles into a ribonucleoprotein complex with LARP7, MEPCE, and HEXIM1 to sequester the positive transcription elongation factor b (P-TEFb), which consists of CDK9 and Cyclin T1. This interaction inhibits CDK9 kinase activity, blocking RNA polymerase II C?terminal domain phosphorylation at serine 2 and enforcing transcriptional pausing. HEXIM2 activity is modulated by upstream signals such as hexamethylene bis?acetamide (HMBA) and NF???B, and upon release of inhibition, P-TEFb drives elongation of target genes including MYC, CCND1, and FOS, as well as HIV Tat?mediated transactivation.
HEXIM2 knockout in HAP1 cells disrupts this regulatory checkpoint, potentially leading to derepressed P?TEFb activity. Given the CML origin, this model is especially relevant for investigating transcriptional dysregulation in leukemogenesis and cancer. It enables dissection of how HEXIM2 loss influences proliferation, differentiation, and response to CDK9 inhibitors, providing insights into therapeutic strategies targeting transcriptional elongation machinery.
Research applications include transcriptome profiling by RNA?seq, RT?qPCR quantification of P?TEFb target genes (MYC, CCND1), and ChIP?qPCR for RNA polymerase II pausing index. Co?immunoprecipitation and western blotting assess P?TEFb complex dynamics and phosphorylation status. Flow cytometry facilitates cell cycle and apoptosis analyses, while CDK9 inhibitor sensitivity assays offer pharmacological evaluation. These polyclonal knockout cells provide a versatile tool for studying transcription elongation in disease models. For further information, please contact Ascent Research.
