ABSTRACT
Signal transduction downstream of axon guidance molecules is essential for steering developing axons. Second messengers including cAMP are key molecules shared by a multitude of signaling pathways and are required for a wide range of cellular processes including axon pathfinding. Yet, how these signaling molecules achieve specificity for each of their downstream pathways remains elusive. Subcellular compartmentation has emerged as a flexible strategy to reach such a specificity. Here, we show that point contact-restricted cAMP signals control ephrin-A5-evoked axon repulsion in vitro by modulating focal adhesion kinase (FAK; also known as PTK2) phosphorylation and the assembly and disassembly rate of point contacts. Consistent with this, preventing point contact-specific cAMP signals in developing retinal ganglion cells in vivo alters the refinement of their terminal axonal arbor in the brain. Altogether, our study identifies point contacts as a compartment containing a local cAMP signal required for ephrin-A5-dependent axon guidance and highlights the crucial role of such subcellularly restricted second messenger signals in the wiring of neuronal circuits.
Footnotes
Author contributions
Conceptualization: J.B., X.N.; Formal analysis: J.B., C.G.-B., C.M., X.N.; Funding acquisition: J.B., X.N.; Investigation: J.B., C.G.-B., C.M., A.A., N.A.L.C., I.K., F.R., S.C., X.N.; Methodology: J.B., C.G.-B., X.N.; Project administration: X.N.; Supervision: X.N.; Validation: J.B., X.N.; Visualization: J.B., X.N.; Writing – original draft: X.N.; Writing – review & editing: J.B., C.G.-B., C.F., X.N.
Funding
This work was supported, by grants from Agence Nationale de la Recherche (ANR-18-CE16-0017, ANR-22-CE16-0034), Fondation pour la Recherche Médicale (EQU202003010158) and Unadev (RGCMatch) to X.N. This work was performed in the frame of LABEX LIFESENSES (ANR-10-LABX-65) and of IHU FOReSIGHT (ANR-18-IAHU-0001) supported by French state funds managed by the Agence Nationale de la Recherche within the Investissements d'Avenir program. J.B. was supported by fellowships from the Fondation de France (00099274) and Fondation pour la Recherche Médicale (FDT202204014862). N.A.L.C. was supported by a fellowship from the Swiss National Science Foundation (P500PB_206674).
Data availability
All relevant data can be found within the article and its supplementary information. Full data sets are available upon request to the corresponding author.
