Identification and analysis of the minimal promoter activity of a novel noncoding nuclear RNA gene, AncR-1, from the honeybee (Apis mellifera L.)

Abstract

Previously, we identified a gene for a noncoding nuclear RNA, termed Ks-1, that is expressed preferentially in a restricted set of neurons in the honeybee brain. In the present study, we identified another novel gene, termed AncR-1, whose transcripts were localized to nuclei in the whole cortex region of the honeybee brain, as a candidate novel noncoding nuclear RNA gene. RNA fluorescent in situ hybridization revealed that AncR-1 and Ks-1 transcripts were located in a distinct portion of a single neural nucleus, suggesting that they have distinct functions in brain neurons. cDNA cloning revealed that the AncR-1 transcripts were up to 7 kb in size, had mRNA-like structures, and were alternatively spliced. The reporter assay using Drosophila SL-2 cells demonstrated that a TATA box-like sequence located −30 bp upstream of the 5′ end of AncR-1 cDNA had promoter activity. None of the alternatively spliced AncR-1 cDNA variants contained significant open reading frames, strongly suggesting that AncR-1 transcripts function as novel noncoding nuclear RNAs. Furthermore, in situ hybridization revealed that AncR-1 was expressed not only in the brain but also in the sex organs in the queen and drones and in the hypopharyngeal glands and oenocytes of the worker bees, suggesting that AncR-1 is involved in diverse organ functions. Some of the AncR-1 transcripts enriched in the nuclei of the hypopharyngeal glands were polyadenylated, indicating the presence of mRNA-like AncR-1 transcripts in the nuclei.

Keywords

• honeybee
• noncoding RNA
• nuclear localization
• tissue/organ-specific expression
• brain