Identification and characterization of human BIC, a gene on chromosome 21 that encodes a noncoding RNA.

BIC was originally identified as a gene transcriptionally activated by promoter insertion at a common retroviral integration site in B cell lymphomas induced by avian leukosis virus (Tam et al., Mol. Cell. Biol. 17 (1997) 1490). The human homolog of this gene was cloned and characterized. It consists of three exons within a 13 kb region located in chromosome 21q21. Similar to the avian homolog, the human BIC lacks a long open reading frame (ORF). Highest levels of BIC expression are detected in the spleen and thymus by Northern analysis. In addition, the mouse homolog of BIC was identified. Comparison of BIC cDNAs from human, mouse and chicken reveals 78% identity over 138 nucleotides. However, there is no homology among the multiple short ORFs present in these cDNAs. The region of sequence homology is predicted by computer analysis to form an imperfect RNA duplex, which is structurally similar among the three species. Based on the lack of a conserved ORF and the evolutionary conservation of RNA secondary structure, we presume that BIC functions as a noncoding RNA.