Potential regulatory roles for RNA in cellular development.

In addition to its widely accepted messenger and structural roles, RNA has been implicated in several other biological events: transfer of specificity of the immune response, interferon induction, and infection of plants by viroids. In none of these cases is the mechanism of RNA action understood. As a result of recent advances in the understanding of RNA metabolism in eukaryotic nuclei and potential specificity of nucleases that cleave such RNA, we have suggested specific ways in which "extra" RNA could be involved in regulation of the development of cells. A survey of literature concerning mammalian cell differentiation both in embryos and in the immune system leads to the observation that there appears to be a line of communication between macromolecules on cell surfaces and the genome. Making the conservative assumption that the DNA retains its integrity throughout development, it seems likely that highly specific signals are sometimes required to transfer information from outside the cell to the DNA,resulting in a change in state of differentiation. We propose a way in which RNA could be utilized in this process.