Axon-Schwann cell interactions regulate the expression of c-jun in Schwann cells.

The transcription factor c-jun is selectively expressed by non-myelinating Schwann cells in normal peripheral nerve, and be "denervated," previously myelinatng Schwann cells, after axotomy. When axons regenerate into the distal nerve-stump, the expression of c-jun declines as Schwann cells remyelinate axons. Treating cultured Schwann cells with forskolin, a drug that mimics many of the effects of axon-Schwann cell interactions, decreases the expression of myelin-specific genes. Overexpressing c-jun in cultured Schwann cells, however, does not decrease the expression of a myelin basic protein promoter-reporter construct, indicating that c-jun expression may not directly regulate myelin-specific gene expression. These data suggest that c-jun is invloved in regulating the phenotype of non-myelinating and denervated Schwann cells.