During neural development, endosomal trafficking controls cell shape and motility through the polarized transport of membrane proteins related to cell-cell and cell-extracellular matrix interactions. ADP ribosylation factor 6 (Arf6) is a critical small GTPase that regulates membrane trafficking between the plasma membrane and endosomes. We herein demonstrated that the knockdown of endogenous Arf6 in mouse cerebral cortices led to impaired neuronal migration in the intermediate zone and cytoplasmic retention of N-cadherin and syntaxin12 in migrating neurons. Rescue experiments with separation-of-function Arf6 mutants identified Rab11 family-interacting protein 3 (FIP3)/Arfophilin-1, a dual effector for Arf6 and Rab11, as a downstream effector of Arf6 in migrating neurons. The knockdown of FIP3 led to impaired neuronal migration in the intermediate zone and cytoplasmic retention of N-cadherin in migrating neurons, similar to that of Arf6, which could be rescued by the co-expression of wild-type FIP3 but not FIP3 mutants lacking the binding site for Arf6 or Rab11. These results suggest that Arf6 regulates cortical neuronal migration in the intermediate zone through the FIP3-dependent endosomal trafficking.
Significance Statement: Endosomal trafficking is a critical mechanism that regulates cell motility and shape. During cortical layer formation, migrating neurons undergo dynamic changes in cell motility and shape, but regulatory mechanisms that control endosomal trafficking in migrating neurons have just begun to be elucidated. Here, we demonstrate that Arf6 small GTPase regulates neuronal migration in intermediate zone through FIP3/Arfophilin-1-dependent endosomal transport of N-cadherin. The present findings indicate the importance of the Arf6-FIP3 pathway in the cortical layer formation and the existence of multiple small GTPases that regulate the surface N-cadherin expression in migrating neurons.
The authors declare that they have no conflict of interest.
This work was supported by KAKENHI Grant Number 25640025 from Japan Society for the Promotion of Science (JSPS) (H.S.), Parents Association Grant of Kitasato University School of Medicine (Y.H.), and The Science Research Promotion Fund (Y.H.).