The AP4B1 Knockout HT29 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout population targeting the AP4B1 gene in the human HT29 colorectal adenocarcinoma cell line. This heterogeneous pool enables robust loss-of-function studies of the AP-4 adaptor complex without clonal selection artifacts. AP4B1 encodes the ?? subunit of AP-4, which mediates vesicular trafficking from the trans-Golgi network to endosomes and lysosomes. The polyclonal format is well-suited for bulk functional assays, drug screening, and omics profiling, providing a versatile tool for studying AP-4-dependent cargo sorting in epithelial cells.
The HT29 cell line (ATCC HTB-38) is derived from a primary colon adenocarcinoma of a 44-year-old Caucasian female. These cells exhibit epithelial morphology and can differentiate into enterocyte-like cells under appropriate conditions, making them a widely used model for intestinal epithelial biology and colorectal cancer research. HT29 cells express key trafficking machinery and form polarized monolayers, offering a physiologically relevant context to examine AP4B1 function in epithelial barrier maintenance, protein sorting, and tumor cell biology.
AP4B1 forms the AP-4 complex with AP4E1, AP4M1, and AP4S1. This clathrin-associated adaptor sorts transmembrane cargoes containing YXX?? motifs from the TGN to endosomes and lysosomes. AP-4 recruitment to membranes is regulated by ARF1 and Rab GTPases. Key downstream cargoes include the autophagy protein ATG9A, the AMPA receptor subunit GRIA2, and amyloid precursor protein (APP). Disruption of AP4B1 abrogates complex assembly, causing mislocalization of these cargoes and impairing endolysosomal and autophagic pathways, which can be monitored via LC3/p62 turnover and organelle marker analysis.
In the context of HT29 colorectal epithelial cells, AP4B1 knockout provides a non-neuronal platform to dissect AP-4-mediated trafficking and its contribution to lysosomal homeostasis and autophagy. This model is especially valuable because HT29 cells can polarize and form tight junctions, allowing investigation of AP-4’s role in basolateral sorting and epithelial cell polarity. By studying cargo mislocalization and autophagic dysfunction, researchers can explore potential links between AP-4 deficiency and colorectal cancer phenotypes, including altered cell proliferation, migration, or stress resistance.
Applications include western blotting and immunofluorescence for verifying knockout and monitoring ATG9A or GRIA2 distribution; flow cytometry to quantify surface receptor expression; LC3/p62 autophagy flux assays; subcellular fractionation to assess organelle integrity; and co-immunoprecipitation for protein interaction studies. These cells are also suitable for high-content screens targeting trafficking modulators. For technical support or inquiries, please contact Ascent Research.
