Nogo-66 inhibits the dye-coupling of astrocytic gap junctions in vitro.

Communication between astrocytes via the gap junction is crucial for maintaining homeostasis of the extra-neuronal microenvironment of the central nervous system. Dysfunction of astrocytic gap junctions is involved in many brain disorders. Our previous studies demonstrated a novel co-localization of Nogo-66 receptor at glial gap junctions in rat cerebellum and posterior pituitary. The present study was aimed at exploring whether Nogo-66 can modulate glial gap junctions in vitro. We confirmed the co-localization of Nogo-66 receptor with Cx43 in cultured astrocytes, and stimulated astrocytes with myelin extracts, or Nogo-66-Fc conditioned medium. Finally, we expressed and purified a functionally effective GST-Nogo-66 peptide. Lucifer yellow transfer assay was adopted to measure the gap junction permeability. The results showed that the spreading of Lucifer yellow was inhibited significantly by all three treatments as compared with their corresponding controls. Therefore, this study shows a novel inhibitory effect of Nogo-66 on the permeability of astrocytic gap junctions, suggesting a presumable role of Nogo-66 receptor in modulating the glial gap junction.