Association of dystroglycan and laminin-2 coexpression with myelinogenesis in peripheral nerves

Abstract

To provide clues to the biological functions of dystroglycan–laminin-2 complex in peripheral nerves, we investigated the expressions of Β-dystroglycan and laminin-Α₂ chain in rat sciatic nerve during axonal degeneration and regeneration and during development, as well as in rat dorsal root ganglia. In normal conditions, immunoreactivity of the cytoplasmic domain of Β-dystroglycan was associated with the Schwann cell abaxonal membrane. The immunoreactivities of both Β-dystroglycan and the laminin-Α₂ chain decreased in Schwann cells losing axons during axonal degeneration and progressively increased in remyelinating Schwann cells during axonal regeneration. Interestingly, during axonal degeneration, the abaxonal membrane losing contact with the basal lamina lost the association with Β-dystroglycan immunoreactivity. During development, expression of both Β-dystroglycan and laminin-Α₂ chain strikingly increased during postnatal 7 days, which is a critical period when basal lamina assembly and myelin formation rapidly progress. These results suggest that coexpression of dystroglycan and laminin-2 is associated with myelinogenesis in peripheral nerves. These two proteins may function as an anchorage between the abaxonal membrane and the basal lamina, enabling myelin forma-tion to progress. Β-Dystroglycan and laminin-2 were also coexpressed in satellite cells in dorsal root ganglia, suggesting that interaction of these two proteins plays some role in physiological functions of these cells.