Expression of a conserved mouse stress-modulating gene, Bre: comparison with the human ortholog.

Mouse Bre, an evolutionarily conserved stress-modulating gene, like its human counterpart, is expressed in multiple alternative transcripts. The main transcript, which is ubiquitously expressed, encodes a protein that binds tumor necrosis factor receptor 1 (TNF-R1) and downregulates TNF-induced activation of NF-kappaB. Alternative splicing of mouse Bre occurs only at the 5' region of the gene, generating either nonfunctional transcripts or transcripts that can encode putative protein isoforms differ at the N-terminal sequence. In contrast, alternative splicing of human BRE occurs at either or both ends of the gene; only the 3' alternative splicing can generate functional transcripts that encode putative protein isoforms differ at the C-terminus, occurrence of the 5' alternative splicing only results in forming nonfunctional transcripts. Unlike the human BRE alternative transcripts which are coexpressed at considerable levels with the main transcript, the mouse counterparts are expressed in a restricted pattern and generally in low abundance except in the heart. Both species, however, share a type of Bre alternative transcripts generated by cryptic splicing at a nonstandard, noncanonical acceptor site. Thus, a highly conserved gene in two species can generate alternative transcripts different in both of the sequence structure and expression pattern, as well as a similar class of transcripts resulting from unconventional transcript processing.