AKAP79 Interacts with the Axon Guidance Receptor Robo2

Abstract

A‐kinase anchoring proteins (AKAPs) are scaffolds that bring together complexes containing protein kinase A (PKA) and other signaling molecules. They localize these complexes to specific regions of the cell to regulate numerous signaling pathways. AKAP79 is a neuronal scaffold that coordinates PKA, protein kinase C (PKC), and protein phosphatase 2B (PP2B) signaling at the plasma membrane. The anchoring of these enzymes via AKAP79 is important for the function of numerous receptors.We have identified an interaction between AKAP79 and the axon guidance receptor Robo2 in a mass spectrometry screen. The Roundabout (Robo) family of receptors is involved in both the repulsion of axonal growth cones during pathfinding as well as the stimulation of dendritic branching. This interaction was confirmed by performing GST‐Robo2 pulldowns from mouse brain lysate as well as immunoprecipitations from HEK293 cells overexpressing Robo2 and AKAP79. Further studies demonstrated that the Robo2‐AKAP79 interaction is disrupted by calcium. In addition, we performed in vitro kinase assays to determine whether Robo2 was a substrate for any AKAP79 anchored kinases. We discovered that Robo2 can be phosphorylated by both PKA and PKC. Based on these findings, we hypothesize that the AKAP79 signaling complex may regulate the essential developmental functions of Robo2.This work was supported in part by NIH grant GM48231.