The C5orf22 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population with disrupted C5orf22 gene, encoding MRNIP. This heterogeneous pool harbors loss-of-function mutations, providing a robust model for DNA repair studies. The polyclonal format maintains population diversity, enabling rigorous phenotypic analysis while avoiding clonal artifacts.
HAP1 is a suspension-adapted, near-haploid human CML-derived cell line (disomy of chromosome 8) originating from KBM-7. Its predominantly haploid genome permits unambiguous genotype-phenotype correlations, as the presence of a single allele eliminates confounding heterozygosity. This feature makes HAP1 ideal for functional genomics, knockout screens, and studying gene function in a haploid context, particularly for DNA damage response pathways.
C5orf22 encodes MRNIP, a pivotal protein in the DNA double-strand break (DSB) repair pathway by homologous recombination (HR). Upon DSB induction, ATM kinase is activated and phosphorylates downstream targets, including MRNIP. MRNIP is then recruited to damage sites where it interacts directly with the MRN complex??comprising MRE11, RAD50, and NBS1??to promote end resection. This process is also facilitated by CtIP. Following resection, MRNIP helps load RAD51 and BRCA1 onto single-stranded DNA, enabling strand invasion and HR. Disruption of C5orf22 ablates these functions, leading to defective HR, persistent DNA damage signaling, and genome instability, underscoring its critical role in maintaining genomic integrity.
In the haploid HAP1 context, knockout of C5orf22 yields a clean loss-of-function phenotype, as the absence of a second allele precludes masking effects. This enhances the detection of DNA repair deficiencies, such as reduced RAD51 focus formation and hypersensitivity to genotoxic agents like ionizing radiation or PARP inhibitors. The model is thus ideally suited for probing MRNIP’s role in DNA repair, genome instability, and cancer, as well as for identifying synthetic lethal interactions in an isogenic background.
Applications include functional genomics, DNA repair pathway analysis, and cancer biology research. The polyclonal cells are suitable for genetic interaction mapping, drug sensitivity/resistance screens, and HR efficiency assays. Typical readouts encompass Western blotting for phosphorylated ATM and ??H2AX, immunofluorescence for RAD51 foci, cell viability after genotoxic challenge, HR reporter assays, flow cytometry for cell cycle, and clonogenic survival. For more information, please contact Ascent Research.
