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. IMAGES:

在神经元中，学界普遍认为一套特化的蛋白质合成机器可在树突的局部区域（尤其是突触连接下方）行使功能，从而实现在原位快速调控突触后蛋白质组的组成。该假说已通过在上述区域中鉴定到多聚核糖体（polyribosomes）与特定信使核糖核酸（mRNA）得到了佐证。本研究报道了在树突中发现的一类特异性RNA聚合酶III（RNA polymerase III）转录本。该RNA为非编码RNA，长度152个核苷酸，属于单基因转录本，被命名为BC1 RNA，其表达几乎仅局限于神经系统。在成年大鼠以及发育后期的幼年大鼠体内，BC1 RNA可在中枢与外周神经系统中部分神经元的树突与胞体中检测到其表达。BC1 RNA与树突mRNA及多聚核糖体的共定位现象，提示其可能在神经元突触后区域的特定转录前或转录后过程中发挥功能，且该功能可能依托于高分子量核糖核蛋白颗粒的功能单元实现。图像：