Drosophila rDNA GENES SHAPE THE STABLE CONTACTS WITH Tlk GENEAT THE EXPRESSION AREA OF SMALL RNAs AND FORM LOOPED DOMAINS INSIDE THE GENE
In experiments on mouse and human cells it was demonstrated that rDNA plays important role in epigenetic regulation of many genes. To identify and study rDNA-contacting genes in Drosophila we used 4С (circular chromosome conformation capture) approach. We detected very stable contacts of rDNA genes within 5-kb region inside Tlk gene residing in X chromosome. This 5-kb region contains small RNAs. After heat shock treatment both the contacts amounts, and the expression level of the gene were increased. Tlk and Rala genes that share the same short bidirectional promoter exhibit different expression levels. Around the region of rDNA contacts inside the Tlk gene, looped domains were formed. We conclude that rDNA contacts-dependent epigenetic regulation via is guided by small RNAs and that the contacts are involved in rearrangements of the looped domains.