The Aak1 Knockout HEI-OC1 Cell Line is a CRISPR/Cas9-edited knockout cell line generated from the HEI-OC1 mouse auditory hair cell line, offering a definitive loss-of-function model for the adaptor-associated kinase 1 (Aak1) gene. AAK1 is a serine/threonine kinase crucial for clathrin-mediated endocytosis, and genetic disruption of this kinase abrogates the phosphorylation of endocytic adaptors, enabling precise analysis of receptor internalization pathways. This cell line provides a homogeneous population of edited cells validated for target gene disruption, suitable for in vitro studies in auditory and neurobiology research.
HEI-OC1 is a conditionally immortalized auditory hair cell line originating from the organ of Corti of the H-2Kb-tsA58 transgenic mouse (Mus musculus). It retains characteristic hair cell markers, mechanotransduction machinery, and the capacity to form ribbon synapses, making it a widely accepted model for inner ear biology. Conditional immortalization via a temperature-sensitive SV40 large T antigen permits proliferation at 33??C with interferon-??, while shifting to 39??C induces differentiation into a postmitotic state, allowing studies on both progenitor and mature hair cell contexts.
Aak1 encodes a kinase that directly phosphorylates the ??2 subunit (AP2M1) of the AP2 complex, a pivotal step in clathrin-mediated endocytosis. AAK1 is stimulated by upstream regulators including epidermal growth factor receptor (EGFR) signaling and phosphatidylinositol 4,5-bisphosphate (PIP2). It interacts with endocytic proteins such as clathrin heavy chain, EPS15, and NECAP1 to phosphorylate AP2M1 at Thr156, thereby enhancing cargo recognition and internalization of receptors like transferrin receptors and AMPA-type glutamate receptors. This positions AAK1 at the intersection of receptor tyrosine kinase cascades, lipid microdomain organization, and synaptic vesicle recycling, controlling membrane protein trafficking and synaptic plasticity.
In sensory hair cells, AAK1-mediated endocytosis is essential for maintaining synaptic vesicle pools at ribbon synapses and recycling membrane components required for mechanotransduction. The HEI-OC1 knockout model provides a physiologically relevant platform to dissect how AAK1-dependent trafficking governs synaptic function, neurotrophin signaling, and cellular responses to ototoxic challenges. By eliminating AAK1 function, this tool aids in unraveling molecular mechanisms underlying hearing loss, neuropathic pain, substance use disorders, and neurodegenerative conditions such as Alzheimer’s disease and schizophrenia, where impaired endocytosis is implicated.
Researchers can utilize this cell line to investigate clathrin-mediated endocytosis through transferrin uptake assays, immunofluorescence visualization of clathrin-coated pits, and flow cytometry-based receptor internalization measurements. Western blotting for AAK1 and phospho-AP2M1 provides direct biochemical validation of kinase activity. Electrophysiological recordings via patch clamp allow functional assessment of synaptic changes, while MTT viability and cisplatin-induced cytotoxicity assays enable high-throughput screening for otoprotective compounds. This knockout line also supports modulator screening for neuropathic pain and studies of synaptic vesicle recycling. For additional information, please contact Ascent Research.
