Combining Neurobehavioral Analysis and In Vivo Photoaffinity Labeling to Understand Protein Targets of Methamphetamine in Casper Zebrafish.

Photoaffinity labeling (PAL) remains one of the most widely utilized methods of determining protein targets of drugs. Although useful, the scope of this technique has been limited to in vitro applications because of the inability of UV light to penetrate whole organisms. Herein, pigment-free Casper zebrafish were employed to allow in vivo PAL. A methamphetamine-related phenethylamine PAL probe, designated here as 2, demonstrated dose-dependent effects on behavior similar to methamphetamine and permitted concentration-dependent labeling of protein binding partners. Click chemistry was used to analyze binding partners via fluoroimaging. Conjugation to a biotin permitted streptavidin pull-down and proteomic analysis to define direct binding partners of the methamphetamine probe. Bioinformatic analysis revealed the probe was chiefly bound to proteins involved in phagocytosis and mitochondrial function. Future applications of this experimental paradigm combining examination of drug-protein binding interactions alongside neurobehavioral readouts via in vivo PAL will significantly enhance our understanding of drug targets, mechanism(s) of action, and toxicity/lethality.