Differentially Expressed Long Noncoding RNAs in the Promoter Region of the fork head Gene in Drosophila melanogaster Detected by Northern Blot Hybridization

Abstract

It is known that long (200-300 nucleotides and longer) non-protein-coding RNAs (ncRNAs) tissue-specifically expressed from the regulatory regions of developmental genes can regulate the transcription of the mRNA of these genes. In this study, an attempt is made to identify differentially expressed ncRNAs in the extended promoter region of the fork head (fkh) gene of the fruit fly Drosophila melanogaster. We investigated four preparations of the total RNA: from embryos, from adult flies (separately from females and males), and from the S2 cell line of cultured Drosophila cells. In the total RNA preparations from embryos and adult flies, the levels of fkh expression differed substantially, whereas in S2 cells its expression is not detected at all (shown in this work). We perform classical Northern blot analysis of gel-separated RNAs hybridized to a series of radioactively labeled DNA fragments corresponding to the adjacent and partially overlapping regions of the promoter region of the fkh gene. Several previously unknown differentially expressed ncRNAs are detected, including those in the regions overlapping with the previously detected regulatory elements (TRE1 and salivary gland enhancer sgE) and the transcription start site of the fkh gene. The collected data complement and clarify the results of the previously conducted RNA-seq experiments, in particular, in terms of the length of the detected RNAs. These results may serve as a foundation for further studies of the mechanisms of tissue-specific regulation of the fkh gene expression.