Intergenerational Transmission of Non-Germline RNAs in Caenorhabditis Elegans

Abstract

In the model organism Caenorhabditis elegans, double-stranded RNA (dsRNA) capable of silencing genes can be introduced anywhere in the animal and will subsequently travel throughout the body and enter most cells, including the germ cells that will go on to become the progeny of the animal. The spreading of dsRNA is known to depend on the protein SID-1, a dsRNA channel. Previous experiments have shown that if dsRNA is introduced into an animal lacking SID-1, but the sid-1 gene is rescued in the next generation, the offspring can still be silenced by the dsRNA, suggesting a SID-1-independent method for dsRNA to enter the germ cells. I demonstrate here that this SID-1-independent transport mechanism involves endocytosis of the dsRNA into developing oocytes, a mechanism which may also be shared in other animals capable of systemic spreading of dsRNA. I also present evidence to suggest that endogenously produced RNAs of non-germline origin that are not necessarily double-stranded may also be transmitted to oocytes. This could represent a method for a mother to influence gene expression in her offspring rapidly in response to changing environmental conditions.