Interaction between fluorescently labeled BMIPP skeleton,a long-chain fatty acid analog,and CD36 forcibly expressed in HEK293 cells

123I-15-(p-iodophenyl)-(R,S)-methyl pentadecanoic acid (BMIPP) is an iodine-123 labeled long-chain fatty acid (LCFA) analog that was developed to examine myocardial LCFA metabolism and has been used as a radiotracer in nuclear cardiology. However, its use is limited because of the specialized features of cardiac scintigraphy. In this study, a novel BMIPP-based probe, in which iodine-123 was replaced with a fluorescent compound, was used to evaluate the direct binding of the BMIPP-basic skeleton to CD36, an LCFA receptor. We performed fluorescence-activated cell sorting (FACS) analysis using a model cell system consisting of HEK293 cells harboring EGFP-fused CD36, and showed that the binding of the fluorescently labeled BMIPP skeleton (Alexa680-BMPP) to cells strictly correlated with CD36 expression levels and was dependent on the concentration of Alexa680-BMPP. The FACS intensities of cells bound to Alexa680-BMPP reverted to those of the control cells after incubation in non-Alexa680-BMPP medium, suggesting that Alexa680-BMPP could bind to CD36 in a reversible manner. We uniquely visualized Alexa680-BMPP bound to EGFP-fused CD36 on the cell surface using fluorescent imaging. Fluorescently labeled BMPP has the potential to be used as a probe to study the interaction between the BMIPP skeleton and CD36.