Pitstop‐2 Upsets The Integrity of Nuclear Pore Complexes (NPCs) by Interaction with β‐Propeller Folds of Npc Scaffold Proteins

Abstract

AbstractThe small compound Pitstop‐2 is a recent potent inhibitor of clathrin‐mediated endocytosis (CME), widely used in biomedical research areas. In recent years, however, it is observed that it exhibits CME‐independent inhibitory effects on nuclear pore complexes (NPCs), the nucleocytoplasmic gatekeepers. NPCs are elaborate proteinaceous transport nano‐machineries of crucial physiological importance rendering them novel targets for various medical applications. They mediate all nucleocytoplasmic transport forming a physiologically essential selective nucleocytoplasmic barrier. The direct Pitstop‐2 disruptive effects on NPCs manifested themselves at both the structural and functional integrity levels. Moreover, they are massive, acute, and detectable at concentrations equal to CME‐inhibitory concentrations. Pitstop‐2 inhibits CME by binding to the terminal β‐propeller domain of the heavy chain of clathrin. Several NPC scaffold proteins, critical for the structural and functional integrity of the NPC, possess β‐propeller folds. Herein, utilizing computational docking analysis, it is demonstrated that Pitstop‐2 exhibits particularly high binding affinities to β‐propeller folds of NPC scaffold proteins, similar to its binding affinity to the terminal β‐propeller domain of clathrin. The authors, therefore, conclude that Pitstop‐2 is a potent disruptor of NPCs, an activity which, separately or in synergy with CME inhibition, may be exploited for a myriad of pharmacological applications.