Abstract
Intergenic transcription is a common feature of eukaryotic genomes and performs important and diverse cellular functions. Here, we investigate the iab-8 ncRNA from the Drosophila Bithorax Complex and show that this RNA is able to repress the transcription of genes located at its 3' end by a sequence-independent, transcriptional interference mechanism. Although this RNA is expressed in the early epidermis and CNS, we find that its repressive activity is limited to the CNS, where, in wild-type embryos, it acts on the Hox gene, abd-A, located immediately downstream of it. The CNS specificity is achieved through a 3' extension of the transcript, mediated by the neuronal-specific, RNA-binding protein, ELAV. Loss of ELAV activity eliminates the 3' extension and results in the ectopic activation of abd-A. Thus, a tissue-specific change in the length of a ncRNA is used to generate a precise pattern of gene expression in a higher eukaryote.
Highlights
Several noncoding RNAs have been identified from the Hox clusters of different species; a few of these have been shown to play key roles in gene regulation [1,2,3,4,5,6,7,8,9,10]
All of the cells making up complex organisms contain the same genetic material, they are able to create the diverse tissues of the body
Understanding how genes are controlled in a tissue-specific fashion is one of the primary interests of molecular genetics
Summary
Several noncoding RNAs (ncRNAs) have been identified from the Hox clusters of different species; a few of these have been shown to play key roles in gene regulation [1,2,3,4,5,6,7,8,9,10]. One of these ncRNAs is the 92 Kb, spliced and polyadenylated transcript called the iab-8 ncRNA. Female sterility has been directly linked to ectopic hth, Ubx and abd-A in the CNS[1, 15,16,17]
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