Axonal targeting of Caspr2 in hippocampal neurons via selective somatodendritic endocytosis

作者：Bel Christophe; Oguievetskaia Ksenia; Pitaval Christophe; Goutebroze Laurence; Faivre Sarrailh Catherine^*

来源：Journal of Cell Science, 2009, 122(18): 3403-3413.

DOI：10.1242/jcs.050526

• Node of Ranvier
• Juxtaparanode
• Neuronal polarity
• PKC phosphorylation

Contactin-associated protein 2 (Caspr2) is a neuronal membrane protein that is mutated in autism and related disorders. Although it is highly enriched at juxtaparanodes of Ranvier where it is essential for Shaker-type K( ) channel clustering, little is known about its function and regulation. In the present study, we examined the polarized expression of Caspr2 in hippocampal neurons using extracellular hemagglutinin (HA)-tagged Caspr2 constructs. We found that Caspr2 was targeted to the axonal surface, but colocalized with early endosomes in the somatodendritic compartment. The inhibition of endocytosis using a Dynamin-1 mutant or treatment with Dynasore prevented Caspr2 internalization from the dendrites and cell body. We identified a short sequence included into the 4.1B-binding domain that is required for the endocytosis of Caspr2. This sequence contains a protein kinase C (PKC) substrate motif on Thr1292, and point mutation of this residue or treatment with a PKC inhibitor prevented the somatodendritic internalization of Caspr2. Thus, the PKC-dependent trafficking of Caspr2 underlies its polarized expression in hippocampal neurons.

• 出版日期2009-9-15