NADPH-dependent oxidation of CRMP2 through a MICAL1-Prx1 redox relay controls neurite outgrowth

CRMP2/DPYL2 is an effector protein in the semaphorin signaling pathway that controls cytoskeletal dynamics, linking extracellular signals to the formation of axonal networks. CRMP2 is regulated by post-translational modifications including a dithiol-disulfide redox switch. The mechanisms of reduction of this switch were established, the signal-induced oxidation, however, remained unclear. Here, we show that CRMP2 is oxidized through a redox relay involving the flavin-mooxygenase MICAL1 and the peroxidase Prx1 as specific signal transducers. Using molecular oxygen and electrons provided by NADPH, MICAL produces hydrogen peroxide and specifically oxidizes Prx1 through direct interactions between the proteins. Subsequently, Prx1 oxidizes CRMP2. The lack of any components of this redox relay dysregulates neurite outgrowth. Consequently, both oxidation and reduction of CRMP2 require reducing equivalents in the form of NADPH.