Welcome to the Siomi Lab web site. Our laboratory is investigating RNA silencing pathways, in which cognate RNA targets are inactivated by small RNA–Argonaute complexes. Key steps in the RNA silencing pathway are shared by a diverse set of gene regulatory mechanisms. These include mechanisms that silence endogenous genes, particularly genes involved in development and stem cell maintenance, and mechanisms that restrain the expression of transposable elements (TEs) or viruses and direct transcriptional gene silencing. Our research focuses on the biogenesis of small guide RNAs, the RNA induced silencing complex (RISC), RISC assembly, and their role in cellular gene expression and TE silencing.