SYNCRIP, a component of dendritically localized mRNPs, binds to the translation regulator BC200 RNA

Dendritic transport of (m)RNA molecules and localized translation at post-synaptic sites is connected to synaptic plasticity and memory formation. Brain cytoplasmic RNA, 200nt (BC200 RNA) is a brain-specific, small non-messenger RNA with a somatodendritic distribution in primate neurons. The transcript is a component of a ribonucleoprotein particle that is thought to act as a regulator of decentralized translation in dendrites. To elucidate the cellular function of the BC200 ribonucleoprotein particle, we purified BC200 RNA-binding proteins from human brain. Here, we describe the interaction of human Synaptotagmin-binding cytoplasmic RNA interacting protein (SYNCRIP) with BC200 RNA. SYNCRIP was recently characterized as a component of large mRNA transport granules in neurons and is probably involved in local protein synthesis at post-synaptic sites. Our in vitro binding studies demonstrate that SYNCRIP interacts specifically with BC200 RNA and that binding is mediated through its N-terminal RNA recognition motifs and the internal A-rich region of BC200 RNA, respectively. Furthermore, immunoprecipitation experiments indicate an in vivo association of SYNCRIP and BC200 RNA in human brain. Thus, SYNCRIP may recruit BC200 RNA into mRNA transport complexes involved in the regulation of localized translation in dendrites.