Expression of dystroglycan complex in satellite cells of dorsal root ganglia

In Schwann cells, the transmembrane glycoprotein beta-dystroglycan composes the dystroglycan complex together with the extracellular glycoprotein alpha-dystroglycan, which binds laminin-2 (alpha2/beta1/gamma1), a major component of the Schwann cell basal lamina. In the Schwann cell cytoplasm, beta-dystroglycan is anchored to a dystrophin isoform, Dp116. In this study, we investigated the expression of beta-dystroglycan, Dp116 and the laminin-alpha2 chain in satellite cells of rat dorsal root ganglia (DRGs). Immunohistochemical study showed that immunoreactivities for beta-dystroglycan and Dp116 were both localized to the outer rim of neuron-satellite cell and axon-Schwann cell units, indicating that both satellite and Schwann cells expressed these proteins in DRGs. Immunoreactivity for the laminin-alpha2 chain was detected in a similar location, indicating that the basal lamina surrounding satellite and Schwann cells in DRGs contained laminin-2. Ultrastructurally, immunoreactivity for the cytoplasmic domain of beta-dystroglycan as well as that for Dp116 was most intense in the cytoplasm just underlying the outer membrane of satellite cells. The immunoreactivity for laminin was associated with the outer surface of those cells, suggesting that it was localized in the surrounding basal lamina. These results indicate that the dystroglycan complex is expressed in the satellite cell outer membrane and involved in the adhesion with the basal lamina through the interaction with laminin-2.