The HS3ST1 Knockout HAP1 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the near-haploid human HAP1 cell line, engineered for functional disruption of the HS3ST1 gene encoding heparan sulfate 3-O-sulfotransferase 1. This product provides a mixed population of edited cells with heterogeneous mutations, enabling loss-of-function studies without clonal isolation. The knockout model serves as a versatile tool for dissecting the role of 3-O-sulfated heparan sulfate in coagulation and growth factor signaling.
HAP1 is a near-haploid, fibroblast-like adherent cell line originating from the KBM-7 chronic myeloid leukemia background, characterized by a haploid karyotype of 23 chromosomes. This unique genetic simplicity facilitates recessive genetic screens and functional genomics assays, as single-copy gene disruption unmasks loss-of-function phenotypes without confounding allelic complexity. HAP1 cells retain key signaling pathways and are widely adopted for CRISPR-based knockout studies, providing a consistent background for analyzing HS3ST1-dependent functions.
HS3ST1 catalyzes the transfer of sulfate to the 3-OH position of glucosamine residues in heparan sulfate chains, generating an antithrombin III-binding pentasaccharide motif. This modification markedly accelerates antithrombin III-mediated inhibition of thrombin and Factor Xa, establishing HS3ST1 as a critical regulator of the coagulation cascade. Beyond hemostasis, 3-O-sulfated heparan sulfate domains interact with growth factors including FGF2, VEGF, and Wnt ligands, facilitating their binding to cognate receptors such as FGFR1, VEGFR2, and Frizzled/LRP5/6 complexes. These interactions potentiate downstream signaling through ERK1/2, AKT, and ??-catenin pathways, influencing cell proliferation, migration, and angiogenesis. Upstream regulators TNF-??, IL-1??, and TGF-?? modulate HS3ST1 expression, linking inflammatory cues to heparan sulfate fine structure. Key interacting partners??antithrombin III, thrombin, Factor Xa, FGF2, VEGF, and syndecan-1??physically engage sulfated epitopes, while glypican-1 may cooperate in presenting heparan sulfate chains at the cell surface.
In the HAP1 context, disruption of HS3ST1 abrogates the biosynthesis of antithrombin III-binding heparan sulfate, providing a clean loss-of-function system to dissect anticoagulant mechanisms absent of genetic redundancy. The haploid genome simplifies genotype-phenotype correlations, enabling robust assessment of HS3ST1-dependent effects on coagulation, growth factor signaling, and cellular behaviors. This polyclonal population preserves allelic diversity while ensuring complete gene disruption, making it suitable for pooled screens and comparing bulk phenotypic outputs. The model is particularly relevant for studying hereditary angioedema, where HS3ST1-linked heparan sulfate modulates contact system activation, and for exploring how tumor-associated changes in heparan sulfation influence cancer progression.
Researchers can utilize these cells in a range of experimental workflows: antithrombin-binding assays using surface-immobilized heparin cofactor II or fluorescence-based thrombin inhibitors, coagulation assays including aPTT and calibrated automated thrombography, and LC-MS disaccharide analysis to profile 3-O-sulfated heparan sulfate species. For growth factor signaling studies, FGF2-stimulated phospho-ERK western blotting, VEGF-induced phospho-AKT detection, and Wnt3a/??-catenin reporter assays provide quantitative readouts of pathway activity. Functional assays such as MTS proliferation, Transwell migration/invasion, and endothelial tube formation model HS3ST1 contributions to angiogenic and metastatic phenotypes. Transcriptional profiling via RNA-seq can identify pathway networks dysregulated upon HS3ST1 loss. These polyclonal knockout cells are ideal for high-throughput genetic screens exploiting the HAP1 haploid background. For further information, please contact Ascent Research.
