Overexpression of and RNA interference with the CCAAT enhancer-binding protein on long-term facilitation of Aplysia sensory to motor synapses

Abstract

In the marine mollusk Aplysia, the CCAAT/enhancer-binding protein, ApC/EBP, serves as in immediate early gene in the consolidation of long-term facilitation in the synaptic connection between the sensory and motor neurons of the gill-withdrawal reflex. To further examine the role of ApC/EBP) as a molecular switch of a stable form of long-term memory, we cloned the full-length coding regions of two alternatively spliced forms, the short and long form of ApC/EBP. Overexpression of each isoform by DNA microinjection resulted in a 16-fold increase in the expression of the coinjected luciferase reporter gene driven by in ERE promoter. In addition, when we overexpressed ApC/EBP in Aplysia sensory neurons, we found that the application of a single pulse of 5-HT that normally induced only short-term facilitation now induced long-term facilitation. Conversely, when we attempted to block the synthesis of native ApC/EBP by microinjecting double-strand RNA or antisense RNA, we blocked long-term facilitation in a sequence-specific manner. These data support the idea that ApC/EBP is both necessary and sufficient to consolidate short-term memory into long-term memory. Furthermore, our results suggest that this double-strand RNA interference provides,I powerful tool in the study of the genes functioning in learning and memory in Aplysia by specifically inhibiting both the constitutive and induced expression of the genes.