The DRD4 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population targeting the human DRD4 gene, designed to eliminate endogenous DRD4 expression. This heterogeneous pool of HAP1 cells carries gene-disrupting mutations, enabling robust loss-of-function studies without single-cell cloning. The polyclonal format provides a practical model for investigating dopamine D4 receptor signaling in a genetically tractable background.
The host HAP1 cell line is a near-haploid, fibroblast-like line derived from a male patient with chronic myeloid leukemia. Its near-haploid karyotype simplifies genetic manipulation, as disruption of a single allele is sufficient to abolish gene function. HAP1 cells are widely employed in genetic screens, signaling pathway analysis, and drug discovery due to their stable proliferation, well-characterized proteome, and compatibility with high-throughput and imaging-based assays.
The DRD4 gene encodes the dopamine D4 receptor, a Gi/Go-coupled GPCR. Upon dopamine binding, DRD4 inhibits adenylyl cyclase, reducing intracellular cAMP and thereby dampening PKA activity and phosphorylation of downstream effectors CREB and DARPP-32. Receptor desensitization occurs via GRK2/3-mediated phosphorylation and ??-arrestin-2 (ARRB2) recruitment. DRD4 also interacts with DRD2 and Dishevelled proteins (DVL1), suggesting roles in receptor heterodimerization and crosstalk with Wnt pathways. Additionally, ERK signaling can be modulated downstream, influencing neuronal excitability and behavioral responses.
In HAP1 cells, knockout of DRD4 eliminates endogenous D4 receptor, establishing a clean cellular background for dissecting signal transduction. The near-haploid state ensures unambiguous loss-of-function, making the model ideal for genotype-phenotype correlations. Given DRD4??s association with ADHD, schizophrenia, and substance abuse, this system allows mechanistic interrogation of disease-relevant pathways without neuronal complexity. Ectopic expression of disease-linked variants can be used to assess functional deficits in cAMP modulation, receptor trafficking, and ??-arrestin-mediated signaling, advancing understanding of neuropsychiatric pathophysiology.
This polyclonal knockout pool is suited for a wide array of assays: cAMP immunoassays following dopamine dose-response, Western blotting for phospho-CREB and DARPP-32, and RT-qPCR for transcriptional targets. ??-arrestin recruitment (BRET/FRET) can be measured after transient expression of wild-type or mutant DRD4. The cells further support drug screening for selective DRD4 agonists or antagonists, with direct relevance to ADHD and addiction research. For additional technical information, please contact Ascent Research.
