NEUREGULIN EXPRESSION IN PNS NEURONS - ISOFORMS AND REGULATION BY TARGET INTERACTIONS

Neuregulins have several important functions in the development of the peripheral nervous system, acting on both developing Schwann cells an d muscle fibers. To determine whether these factors are also important for peripheral nerve regeneration, we have analyzed neuregulin expres sion in motor and sensory neurons by Northern blots and in situ hybrid ization. The results of this analysis show that the predominant neureg ulin isoform expressed in these neurons is a navel transmembrane splic e variant. After axotomy, there is a vapid decline in neuregulin expre ssion in both motor and sensory neurons, but following reinnervation o f target tissues, neuregulin expression returns to near normal levels. These results indicate that the normal expression of neuregulins in t hese neurons is maintained by the interactions with target tissues.