Identification of mRNAs localizing in the postsynaptic region

Local protein synthesis using mRNAs readily distributed in the dendrites is believed to play an important role in maintaining the already expressed sy naptic plasticity. To find proteins translated in the postsynaptic region, such as neuronal dendrites, we tried to identify the mRNAs associated with the postsynaptic density (PSD) fraction prepared from a rat's forebrain. Th e PSD-associated mRNAs were amplified by reverse transcriptase-based polyme rase chain reaction (RT-PCR), separated by polyacrylamide gel electrophores is, and sequenced. The database search revealed, among 130 mRNAs sequenced, 17 known and 108 unknown sequences, while five mRNAs were too short for th e search. Of the mRNAs with unknown sequences, we selected 33 genes with a length longer than 150 bases, performed in situ hybridization, and found th at at least 12 mRNA types were localized in the dendrites. These results su ggest that a large number of mRNAs localize around the postsynaptic area of the neuronal cells in the central nervous system. In addition, our method proved efficient in identifying collectively the mRNAs localizing in the de ndrites. (C) 1999 Elsevier Science B.V. All rights reserved.