The HPD knockout HAP1 polyclonal cells are a CRISPR/Cas9-edited polyclonal knockout population of the human HPD gene, generated in the HAP1 cell line. This product provides a genetically disrupted, loss-of-function model for studying 4-hydroxyphenylpyruvate dioxygenase in relevant cellular contexts. The polyclonal format ensures representation of diverse editing events, facilitating robust functional assays without clonal selection biases. These knockout cells are designed for researchers investigating tyrosine catabolism, metabolic disorders, and related signaling pathways. As a ready-to-use model, they enable efficient dissection of HPD??s role in human disease and metabolism.
The HAP1 host cell line is a human haploid adherent line derived from a male chronic myeloid leukemia patient, exhibiting a near-haploid karyotype and fibroblast-like morphology. Its haploid nature simplifies genetic manipulation and allows straightforward generation of complete loss-of-function phenotypes, as only one allele requires disruption to abolish gene function. HAP1 cells are widely employed in functional genomics, CRISPR screening, and haploid genetic studies due to their tractable genetics and reproducibility. The HPD knockout in this background provides a clean, isogenic system to assess gene function without confounding diploid gene compensation.
Mechanistically, HPD encodes 4-hydroxyphenylpyruvate dioxygenase, which catalyzes the conversion of 4-hydroxyphenylpyruvate to homogentisate in the tyrosine degradation pathway, utilizing Fe2+ and molecular oxygen. This reaction links upstream tyrosine metabolism to downstream generation of fumarate and acetoacetate. HPD expression is regulated by glucocorticoids, cAMP, and the transcription factor HNF4A. The enzyme is inhibited by NTBC (nitisinone), a clinically used tyrosinemia type I therapy. Disruption of HPD causes accumulation of 4-hydroxyphenylpyruvate and tyrosine, manifesting as tyrosinemia type III or hawkinsinuria, thereby establishing the knockout as a disease-relevant model.
In the HAP1 haploid background, HPD knockout eliminates residual enzyme activity, providing a definitive loss-of-function model to study the consequences of impaired tyrosine degradation. This system is particularly suited for metabolic profiling, as the near-haploid state avoids allelic complexity and simplifies interpretation of phenotypic data. Researchers can leverage this model to explore cellular responses to tyrosine overload, assess NTBC efficacy, or dissect interactions with upstream regulators like HNF4A. The combination of a well-characterized host line and a defined gene disruption offers a reproducible platform for basic and translational research in amino acid metabolism.
These HPD knockout HAP1 cells enable diverse experimental applications including metabolic profiling by LC-MS of tyrosine and 4-hydroxyphenylpyruvate, HPD enzyme activity measurement, and cell viability analysis under tyrosine stress. They are suited for modeling tyrosinemia type III, evaluating HPD inhibitors, and investigating transcriptional regulation via RT-qPCR and western blotting. The polyclonal population ensures robust functional assays without clonal bias. For further details or to discuss custom applications, please contact Ascent Research.
