FAK and PYK2 are specifically associated with the activated phagocytic receptor complexes from human U937 cells.

The innate immune system is the first shield against foreign attack inside the human body, and it is usually carried out with phagocytosis. An essential macrophage cell surface protein is the Fc receptor which contributes to the engulfment of unknown antigens. One of the important members of Fc receptors is the gamma receptor that binds to the immunoglobulin G (IgG) ligand. Another key receptor in this study is the CD36 receptor, which plays a crucial role in the progression of atherosclerosis, the hardening of arteries, with its ligand oxidized low-density lipoprotein (OxLDL). In this report, protein tyrosine kinase enzymes have been detected in the involvement of receptor complexes with human U937 macrophages, specifically PTK2 and PTK2b genes. Protein tyrosine kinases were known to promote cell migration as a main player in intracellular signal transduction cascades in relation to extracellular stimuli. Cell surface proteins are essential for the immunization of various diseases; yet, the molecular machinery of surface receptors remains unclear. This research primarily examined the dynamic nature of protein tyrosine kinases in an ongoing investigation of macrophage cell surface receptors, particularly the role of Fc γ and CD36 receptors with their ligands IgG and oxLDL coated beads in phagocytosis. Our report demonstrates a novel role of PTK2 and PTK2b functions in relation to U937 CD36-mediated phagocytosis. The Phagocytic efficiency of U937 macrophages was analyzed using laser scanning confocal microscope after silencing the cells with siRNA followed by quantitative counting of phagocytosis. The PF drug FAK inhibitor was also introduced to compare the phagocytic efficiency of siRNA cells.