Is Clathrin Involved in Internalization of The Small Molecule Berberine by Primary Mouse Mast Cells?

The internalization and endocytosis of small molecules is a process that relies on either passive diffusion across the cell membrane or active transport through complex endocytic pathways such as pinocytosis. Using the fluorescent benzylisoquinoline compound berberine (BBR) as a tool, we analyzed the internalization of this small molecule by differentiated mouse bone marrow-derived mast cells. Our recent data showed that internalization of this compound was energy-and time-dependent and was increased when cells were treated with the differentiation cytokine, interleukin-3 (IL-3). In this commentary, we examine some of the possible mechanisms of internalization and provide further data to show that this process is partially dependent on clathrin-mediated endocytosis. Our hypothesis is that BBR internalization may utilize several pathways of internalization depending upon cell activation and proliferation.