The CCL21 Knockout HEK293T Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population designed for targeted disruption of the CCL21 gene in HEK293T cells. This product provides a heterogeneous pool of edited cells lacking functional CCL21 expression, eliminating secretion of the homeostatic chemokine CCL21 without relying on clonal selection. The polyclonal format preserves population-level diversity while enabling loss-of-function studies that focus on the collective effects of gene disruption. By abolishing CCL21 production, this model serves as a versatile tool for investigating the paracrine roles of CCL21 in immune cell communication and tissue microenvironments.
HEK293T cells are a widely used human embryonic kidney epithelial cell line that stably expresses the SV40 large T antigen. This modification permits episomal replication of plasmids containing the SV40 origin of replication, resulting in high-level transient protein expression and efficient viral production. The epithelial origin and robust growth characteristics of HEK293T cells make them an ideal host for heterologous expression and functional genomics applications. Their ease of transfection and well-characterized signaling background facilitate the introduction of CRISPR/Cas9 components to generate gene knockouts. In this product, the HEK293T background provides a clean cellular context for studying CCL21-dependent mechanisms, as these cells do not naturally engage in immune cell trafficking but can be engineered to express relevant receptors or used in coculture systems.
CCL21 is a homeostatic chemokine that orchestrates lymphocyte and dendritic cell homing to secondary lymphoid organs through high-affinity binding to the CCR7 receptor. Downstream of CCR7, CCL21 activates G??i/o proteins, leading to inhibition of adenylyl cyclase, reduced cAMP levels, and modulation of PKA activity. Simultaneously, ??-arrestin-mediated signaling stimulates the ERK and p38 branches of the MAPK cascade as well as the PI3K/Akt pathway, promoting cytoskeletal reorganization and directed cell migration. Upstream regulation of CCL21 expression involves pro-inflammatory cytokines such as TNF-?? and IL-1??, as well as lymphotoxin ?? receptor signaling through the NIK/NF-??B pathway. Additional molecular interactions include binding to glycosaminoglycans like heparan sulfate for gradient formation, and scavenging by atypical chemokine receptors ACKR4 and DARC, which fine-tune chemokine availability.
Knockout of CCL21 in HEK293T cells specifically removes the chemokine signal that would otherwise be secreted into the extracellular environment. Since HEK293T cells lack endogenous CCR7 expression, this model isolates the ligand-producing function and permits dissection of CCL21-mediated paracrine effects when cocultured with immune cells. The polyclonal nature of the knockout population ensures that the full spectrum of edited alleles is represented, making it suitable for studies where clonal variation is not desired, such as pooled functional screens or bulk chemotaxis assays. By eliminating CCL21 secretion, researchers can directly assess how loss of this chemokine alters dendritic cell trafficking, T cell migration, or lymph node organization-like structures in vitro, providing mechanistic insight into immune surveillance and inflammation.
The CCL21 Knockout HEK293T Polyclonal Cells support a broad range of research applications, including chemokine signaling and immune cell migration studies, investigation of cancer immune evasion mechanisms, dendritic cell homing assays, and screening of CCR7 antagonists. Representative experimental workflows include ELISA for CCL21 secretion, Western blot confirmation of knockout, transwell migration/chemotaxis assays, phospho-MAPK/Akt analysis, immunofluorescence for cell migration, RT-qPCR for downstream gene expression, and flow cytometry to monitor CCR7 receptor levels. This model is particularly valuable in coculture systems where the interplay between CCL21-producing cells and CCR7-expressing immune cells is examined. For additional technical details or to discuss custom modifications, please contact Ascent Research.
