The AROM gene, spliced mRNAs encoding new DNA/RNA-binding proteins are transcribed from the opposite strand of the melanin-concentrating hormone genein mammals

Melanin-concentrating hormone (MCH) mRNA expression is induced by nerve gro wth factor and lithium in PC12 cells, whereas three large MCH RNA species a re found in untreated cells. In this study, we investigated the structures, regulations of expression, and putative functions of these transcripts. No rthern blot, rapid amplification of cDNA ends-polymerase chain reaction, re verse transcriptase-polymerase chain reaction, and sequencing experiments d emonstrated that they are antisense RNAs complementary to the MCH gene. Two classes of antisense RNAs could be discriminated as follows: 1) non-coding unspliced RNAs that overlap mainly the coding part of the MCH gene; 2) spl iced variant mRNAs complementary to the 3'-flanking end of the MCH gene and that encode putative proteins containing DNA/RNA binding domains. We named this new transcriptional unit AROM for antisense-RNA-overlapping-MCH gene. Spliced variant AROM mRNAs are expressed in a broad range of rat organs. W estern blot and immunohistochemistry experiments revealed several proteins with cytoplasmic but also nuclear localization in PC12 cells. Time course s tudies during nerve growth factor and lithium treatment of PC12 cells indic ated a reciprocal regulation of the MCH and AROM gene transcripts, reflecte d also at the level of AROM proteins. The major translational product is a 64-kDa protein (AROM-p64). Recombinant AROM-p64 displayed high binding to s ingle-stranded DNA and poly(A) homopolymers suggesting that this protein co uld play a role in mRNA maturation/metabolism.