Practice question

MDCK cells are premier model for epithelial physiology because they form highly polarized monolayers with distinct apical membrane enriched in glycoproteins with GPI anchors and basolateral membrane containing receptors for growth factors, enabling study of protein sorting signals such as tyrosine motifs and raft-dependent trafficking via Par3-Par6-aPKC polarity complex. They develop tight junctions that restrict paracellular diffusion, allowing measurement of drug permeability, P-glycoprotein mediated efflux, and toxicant effects on barrier integrity. In influenza research, MDCK is gold standard because expression of sialyltransferases creates receptors for influenza hemagglutinin: alpha2,3 sialic acids recognized by avian strains and alpha2,6 by human strains, allowing viral attachment, endocytosis, and productive replication with observable cytopathic effect. Hemagglutination assays, plaque titration, and testing of neuraminidase inhibitors oseltamivir and zanamivir rely on MDCK. This dual utility for membrane transport and influenza distinguishes MDCK from fibroblast lines used only for signaling or muscle lines for contractile studies. Co-culture with immune cells models viral transmission across epithelial barriers relevant to pandemic preparedness. This knowledge strengthens laboratory safety, protocol reproducibility, and regulatory compliance critical for translational research and clinical applications, ensuring reliable data and workforce protection.