A DEVELOPMENTAL GENE (TOLLOID BMP-1) IS REGULATED IN APLYSIA NEURONS BY TREATMENTS THAT INDUCE LONG-TERM SENSITIZATION/

Long-term sensitization training, or procedures that mimic the trainin g, produces long-term facilitation of sensory-motor neuron synapses in Aplysia. The long-term effects of these procedures require mRNA and p rotein synthesis (Montarolo et al., 1986; Castellucci et al., 1989). U sing the techniques of differential display reverse transcription PCR (DDRT-PCR) and ribonuclease protection assays (RPA), we identified a c DNA whose mRNA level was increased significantly in sensory neurons by treatments of isolated pleural-pedal ganglia with serotonin for 1.5 h r or by long-term behavioral training of Aplysia. The effects of serot onin and behavioral training on this mRNA were mimicked by treatments that elevate cAMP. The Aplysia mRNA increased by serotonin and behavio ral training was 41-45% identical to a developmentally regulated gene family which includes Drosophila tolloid and human bone morphogenetic protein-1 (BMP-1). Both tolloid and BMP-1 encode metalloproteases that might activate TGF-beta (transforming growth factor beta)-like molecu les or process procollagens. Aplysia tolloid/BMP-1-like protein (apTBL -1) might regulate the morphology and efficacy of synaptic connections between sensory and motor neurons, which are associated with long-ter m sensitization.