The H2AJ Knockout HeLa Polyclonal Cells constitute a CRISPR/Cas9-edited polyclonal cell population featuring targeted disruption of the human H2AJ gene, which encodes a replication-independent histone H2A variant that accumulates during cellular senescence. This loss-of-function model enables robust investigation of H2AJ-dependent chromatin remodeling and senescence programs without clonal selection, preserving the biological heterogeneity characteristic of senescent cell populations.
The host HeLa line is a human cervical adenocarcinoma epithelial cell model that is HPV18-positive. Constitutive expression of viral oncoproteins E6 and E7 inactivates the tumor suppressors p53 and retinoblastoma protein (RB1) through ubiquitin-mediated degradation, thereby abrogating the p53/p21 and p16/RB1 pathways. This genetic background provides a permissive environment for studying senescence mechanisms independent of canonical tumor suppressor checkpoints.
H2A.J transcription is induced by DNA damage?Cactivated kinases ATM and ATR and is further regulated by p53 and the cyclin-dependent kinase inhibitors p21 and p16. The histone variant is incorporated into chromatin, where it interacts with linker histone H1, HP1??, macroH2A, and the chromatin remodelers ATRX and DAXX to promote the assembly of senescence-associated heterochromatic foci (SAHF). These repressive domains mediate stable silencing of proliferation-associated genes such as CCNA2 and CCNB1, thereby reinforcing the senescent cell-cycle arrest and modulating the senescence-associated secretory phenotype (SASP).
In HeLa cells, where p53 and RB1 are functionally compromised, H2AJ disruption offers a unique tool to dissect p53/RB1-independent contributions of histone variant dynamics to SAHF formation and gene silencing. The model allows interrogation of whether H2A.J can drive chromatin compaction and proliferation arrest in the absence of canonical tumor suppressors, enabling the study of compensatory pathways involving p21, p16, or other stress-responsive factors. This context is particularly useful for exploring oncogene-induced or oxidative stress?Ctriggered senescence programs that may operate outside the classical p53/RB1 axis.
The polyclonal knockout cells are suitable for senescence and chromatin biology assays, including western blotting for H2A.J, senescence-associated ??-galactosidase staining, and immunofluorescence for SAHF markers (H3K9me3, HP1??). ChIP-qPCR maps H2A.J chromatin occupancy, while RNA-seq reveals transcriptional derepression of cell-cycle genes like CCNA2 and SASP components. Flow cytometry for cell cycle analysis quantifies proliferation changes. These applications support drug discovery, aging research, and cancer epigenetics. For further details, contact Ascent Research.
