Antisense RNAs as envoys in intercellular communication: 20 years later

More than 20 years ago we showed that some types of cells are capable of secreting RNAs. It was suggested that these secreted RNAs could serve as molecular envoys in intercellular communication, for example, these RNAs being complementary to specific sites of the gene in another cell (e.g. to the variable region of immunoglobulin gene) could regulate the expression of genes that contain sites in coding regions complementary to antisense RNA. It has since been proven that eukaryotic cells contain antisense RNAs (particularly microRNAs and small interfering RNAs), which can regulate the expression of genes at the posttranscriptional level (the so-called regulatory pathway of RNA interference). Here I provide a short review of advances in the field of intracellular regulation of gene expression by different types of RNAs. In addition, an overview of recent data on the secretion of RNA molecules by different cell types and possible involvement of these secreted antisense RNAs in intercellular regulation of gene expression in target cells is given.