Small RNA-Guided Transcriptional Gene Activation (RNAa) in Mammalian Cells

Small RNA partnering with Argonaute (Ago) proteins plays important roles in diverse biological processes mainly by suppressing the expression of cognate target sequences. Mounting evidence reveals that the small RNA-Ago pathway can also positively regulate gene expression, a phenomenon termed as RNA activation (RNAa), which is evolutionarily conserved from Caenorhabditis elegans to human. In this chapter, I provide a general overview of mammalian RNAa phenomena and their basic characteristics and discuss recent advances toward understanding the nature of the molecular machinery responsible for RNAa and the development of RNAa-based research tools and therapeutics.