Dendritic location of neural BC1 RNA.

In nerve cells, a specialized protein synthetic machinery is thought to operate in local compartments of dendrites, in particular beneath synaptic junctions, and thereby to facilitate swift adjustments of the postsynaptic protein repertoire in situ. This notion has been supported by the identification of polyribosomes and selected mRNAs in those compartments. In this study, we report the discovery of a specific RNA polymerase III transcript in dendrites. This RNA, a noncoding, 152-nucleotide-long, single-gene transcript known as BC1 RNA, is expressed almost exclusively in the nervous system. In adult rats as well as in immature rats in late developmental stages, BC1 RNA has been located in the dendrites and somata of a subset of neurons in the central and peripheral nervous system. The colocalization of BC1 RNA with dendritic mRNAs and polyribosomes may indicate a role--possibly within the functional unit of a high molecular mass ribonucleoprotein particle--in specific pre- or posttranslational processes in postsynaptic compartments of neurons.