Neural BC1 RNA associates with Pur alpha, a single-stranded DNA and RNA binding protein, which is involved in the transcription of the BC1 RNA gene

BC1 RNA is preferentially expressed in neural cells by RNA polymerase III ( Pol III) and forms ribonucleoprotein particles (RNP) in the somatodendritic domain of neurons. Our previous studies have suggested that, in the nucleu s, BC1 RNA forms an RNP containing a nuclear protein(s) that participates i n the transcription of the BC1 RNA gene. In this study, we have shown that newly synthesized BC1 RNA in purified brain nuclear extracts is immunopreci pitated by an antibody against Pur alpha. Pur alpha is a protein that binds single-stranded DNA and RNA and is known to regulate transcription of Pol II system. Although BC1 RNA is transcribed by Pol III, the BC1 RNA gene has two putative Pur alpha binding sites, which Pur alpha specifically recogni zes. Point mutations within these sites reduced transcriptional activity in vitro, Furthermore, transcription was inhibited by depletion of Pur alpha from the nuclear extracts, either by the coexistence of its binding region of BC1 RNA or by the antibody that was able to precipitate the nuclear BC1 RNP, These observations suggest that BC1 RNA associates with Pur alphau whi ch is involved in the transcription of the BC1 RNA gene. (C) 2000 Academic Press.