The CCNT2 Knockout HAP1 Polyclonal Cells represent a CRISPR/Cas9-edited polyclonal knockout cell population targeting the human CCNT2 gene, which encodes the cyclin T2 regulatory subunit of the positive transcription elongation factor b (P-TEFb) complex. This polyclonal population, generated through bulk gene disruption, provides a genetically heterogeneous loss-of-function model that retains the diversity of editing outcomes, enabling pooled functional studies without single-cell clonal selection. The product is designed for researchers investigating transcriptional elongation mechanisms, HIV-1 replication, and kinase inhibitor responses in a convenient haploid background.
The host HAP1 cell line is a near-haploid human cell line of male origin, originally derived from the KBM-7 chronic myeloid leukemia (CML) line. Its simplified haploid karyotype, with a single copy of most chromosomes, facilitates unambiguous gene targeting and makes it an ideal platform for genetic screens and structure-function analyses. HAP1 cells are widely employed in functional genomics, CRISPR-based screens, and drug target validation, particularly in the context of hematological malignancies.
Cyclin T2 functions as the regulatory subunit of P-TEFb, forming an active complex with the cyclin-dependent kinase CDK9. This complex is recruited to promoters by factors such as BRD4 and the super elongation complex (AFF4/ELL2), where it phosphorylates serine 2 residues in the C-terminal domain (CTD) of RNA polymerase II, releasing paused polymerase and driving productive transcriptional elongation. The activity of P-TEFb is tightly controlled by reversible association with the 7SK small nuclear RNA-HEXIM1 inhibitory complex and is engaged by the HIV-1 Tat protein to hyperactivate viral transcription. Downstream phosphorylation targets include the negative elongation factors NELF and DSIF, while key transcriptional outputs encompass cell cycle regulators like c-Myc and cyclin D1. Upstream signals from transcription factors such as SP1 and NF-??B further modulate CCNT2 expression and P-TEFb function.
In HAP1 cells, disruption of CCNT2 provides a clinically relevant model for studying CML biology, as the parental KBM-7 line harbors BCR-ABL1, the hallmark of CML. The knockout selectively impairs P-TEFb-dependent transcriptional elongation, affecting genes critical for cell proliferation and survival. This system enables dissection of leukemic growth dependencies on transcriptional addiction and offers a tractable platform for evaluating CDK9-targeted therapies in a haploid genetic background, where dosage effects of interacting partners like HEXIM1 or BRD4 can be more readily interpreted.
This polyclonal knockout cell product supports a broad array of experimental applications, including Western blot analysis of RNA polymerase II CTD phosphorylation, RT-qPCR and RNA-seq profiling of elongation-sensitive transcripts, ChIP-qPCR for promoter-proximal polymerase occupancy, and flow cytometry-based cell cycle profiling. It is particularly suited for HIV-1 replication assays to examine Tat-dependent transcription, as well as drug sensitivity screens for CDK9 inhibitors or other P-TEFb modulators. Proliferation and viability assays further enable functional dissection of cyclin T2 in leukemic cell growth. For additional technical specifications, please contact Ascent Research.
