The GNPTAB Knockout HAP1 Polyclonal Cells are a genetically modified population of HAP1 cells created by CRISPR/Cas9-mediated disruption of the GNPTAB locus. This polyclonal knockout product provides a heterogeneous loss-of-function model for studying the role of the alpha/beta subunits of GlcNAc-1-phosphotransferase in lysosomal enzyme trafficking and M6P biosynthesis. This system is particularly useful for elucidating the mechanisms underlying lysosomal storage disorders and screening therapeutic interventions.
The HAP1 cell line is a near-haploid human cell line derived from a male patient with chronic myeloid leukemia (KBM-7). Its primarily haploid karyotype ensures that single-allele gene disruption yields a functional null phenotype, making it an ideal platform for knockout studies. The hematopoietic origin of HAP1 also provides a physiologically relevant model for investigating lysosomal biology and disorders that impact the blood and immune systems. This genetic simplicity minimizes compensatory mechanisms and facilitates clear interpretation of experimental results.
GNPTAB encodes the catalytic alpha and beta subunits of GlcNAc-1-phosphotransferase, a Golgi-resident enzyme responsible for the first step in the synthesis of the mannose-6-phosphate (M6P) tag on lysosomal hydrolases. The enzyme transfers GlcNAc-1-phosphate to mannose residues on nascent enzymes, a modification later processed to M6P, which is recognized by M6P receptors (CI-MPR/CD222 and CD-MPR) for sorting to lysosomes. GNPTAB forms a complex with the regulatory gamma subunit GNPTG, and its transcription is controlled by TFEB within the CLEAR network. Disruption of GNPTAB leads to missorting and hypersecretion of lysosomal enzymes such as cathepsins and sulfatases, causing lysosomal dysfunction characterized by impaired acidification and accumulation of undegraded substrates.
In the HAP1 background, the GNPTAB knockout provides a robust platform for dissecting lysosomal trafficking pathways due to the cell line’s haploid genetics and high editing efficiency. The polyclonal nature ensures population-level consistency while allowing the study of M6P-dependent sorting and lysosomal biogenesis without clonal artifacts. The hematopoietic lineage of HAP1 makes it pertinent for investigating the pathophysiology of mucolipidoses and for evaluating therapies aimed at restoring lysosomal function in myeloid disorders.
This product is suited for diverse applications including western blotting of lysosomal enzymes in cell lysates and conditioned media, RT-qPCR for transcript profiling, immunofluorescence detection of LAMP1/2 and cathepsin D, M6P immunodetection, flow cytometric analysis of lysosomal markers, and enzymatic activity assays. It supports drug screening for M6P-independent enzyme delivery, mechanistic studies of mucolipidosis, and electron microscopy evaluation of lysosomal storage. For technical inquiries, contact Ascent Research.
