Physiological roles of sperm-borne small RNAs

Abstract

The discovery of RNA interference (RNAi) nearly two decades ago revealed a complex and ubiquitous layer of gene expression regulation in both plants and animals. Small noncoding RNAs (sncRNAs), the effectors of RNAi, are present and active in both somatic and germ cells, and appear to play an indispensable role in reproduction. Interestingly, despite cessation of transcription prior to their formation, diverse populations of sncRNAs are present in sperm. While it has been established that sperm-borne sncRNAs are delivered to the oocyte during fertilization, their function and physiological significance in the early embryo remains unclear. To better understand the importance of the paternal sncRNA contribution in the early embryo, this dissertation investigates sperm-borne sncRNAs in multiple contexts. Both miRNA and miRNA / endo-siRNA deficient sperm were generated for fertilization studies, to determine whether the paternal contribution of either class of sncRNA was required for successful early embryo development (Chapter II). To improve our knowledge of the conservation and characteristics of mammalian sperm RNA content, catalogs of both large and small RNA expression were compiled for multiple species, using a methodology that emphasized consistency between datasets (Chapter III). The recent discovery that sperm-borne sncRNAs are involved in epigenetic inheritance prompted an investigation into whether they are active in vinclozolin-induced, epigentically inheritable disease phenotypes (Chapter IV). In these studies, sperm-borne sncRNAs were consistently found to play a non-trivial physiological role in many aspects of mammalian development.