The ALAD Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population designed to disrupt the human ALAD gene in the near-haploid HAP1 cell line. This engineered cell pool enables loss-of-function studies of delta-aminolevulinate dehydratase (ALAD), the enzyme responsible for the second step of heme biosynthesis. The polyclonal nature provides a genetically mixed population with targeted gene disruption, suitable for population-level assays without clonal selection artifacts. This knockout model serves as a versatile tool for investigating heme metabolism, porphyrin synthesis, and related disorders.
The host cell line, HAP1, is a near-haploid chronic myeloid leukemia cell line derived from the KBM-7 line. It exhibits an adherent, fibroblast-like morphology and originates from a male donor. HAP1 cells are widely employed in functional genomics due to their haploidy, which facilitates efficient gene targeting and reduces genetic redundancy, resulting in clear phenotypic readouts after CRISPR/Cas9-mediated gene disruption. The stable karyotype and robust growth characteristics make HAP1 an ideal backbone for generating knockout models for pathway analysis and drug screening.
ALAD encodes an evolutionarily conserved enzyme that catalyzes the condensation of two molecules of delta-aminolevulinic acid (ALA) to form porphobilinogen, a critical precursor in heme biosynthesis. This reaction requires zinc as an essential cofactor and is potently inhibited by lead. ALAD functions downstream of ALAS and upstream of porphobilinogen deaminase (PBGD) within the heme biosynthetic pathway, ultimately contributing to the production of heme, hemoglobin, and cytochromes. The expression and activity of ALAD are transcriptionally regulated by NRF2 and GATA1, and are influenced by heme levels and iron regulatory proteins. Knockout of ALAD eliminates ALA dehydratase activity, leading to accumulation of ALA, reduced porphobilinogen synthesis, diminished heme output, and potential induction of oxidative stress due to ALA auto-oxidation.
In HAP1 cells, ALAD knockout disrupts heme biosynthesis, a pathway essential for hemoglobin assembly and mitochondrial electron transport. The near-haploid background enhances phenotypic penetration, as compensatory paralogs are generally absent. This model recapitulates key features of ALA dehydratase deficiency porphyria and mimics the biochemical effects of lead poisoning, where ALAD inhibition is a primary toxic mechanism. The cells may exhibit altered iron metabolism and increased reactive oxygen species, providing a physiologically relevant platform for studying heme-dependent cellular processes and metabolic diseases.
This polyclonal knockout population supports a wide range of research applications, including heme biosynthesis pathway analysis, lead toxicity modeling, and porphyria disease research. Representative assays include ALAD enzyme activity measurements, porphyrin fluorescence quantification, western blotting for pathway components, RT-qPCR for transcript analysis, heme quantification, and ROS detection. The model is also suitable for drug screening aimed at correcting heme deficiency or mitigating oxidative stress, as well as for functional genomics studies requiring a defined loss-of-function genetic background. For additional information or technical support, please contact Ascent Research.
