Non-coding RNAs in neuronal differentiation and PWS (Year 2)

Funding Summary

Dr. Tollervey is an expert in snoRNA biology. He has been investigating the snoRNAs in the PWS region and has found that loss of the SNORD116 genes alters neuronal maturation in PWS cells (https://www.biorxiv.org/content/10.1101/2023.10.24.563766v1). In year 2 of his funded project, they will use specialized techniques to identify the RNAs and proteins that interact with the PWS-region snoRNAs and will use this information to investigate approaches to activate the PWS genes on the maternally inherited chromosome 15.

Lay Abstract

The genetic information in all organisms, including humans, is encoded in the sequences of very long molecules of DNA. However, to be used the data must be retrieved by copying into a related molecule called RNA. In consequence, RNA metabolism lies at the heart of the information processing systems that fundamentally distinguish living organisms from sets of biochemical reactions. The mRNAs encode the information needed to direct the synthesis of proteins. Others, termed non-coding RNAs (ncRNAs) function more directly, particularly in the machinery of protein synthesis, but more functions likely remain to be found.
Prader-Willi syndrome can be caused by loss of ncRNAs synthesized from the SNHG14 locus. Among these there are two sets of closely related RNAs collectively called SNORD115 and SNORD116, which are made by being cut out of a very long SNHG14 ncRNA. A gene deletion that only removes the part of SNHG14 that generates SNORD116 is enough to cause PWS. These RNAs clearly have important functions - but we do not know what they are. Discovering those functions will reveal the fundamental basis of PWS. We plan to approach this task by identifying proteins and RNAs that interact with SNHG14-derived ncRNAs.
SNORD116 is part of large family of RNAs that are termed small nucleolar RNAs (snoRNAs), that our group has studied since the 1980s. Most snoRNAs are expressed in all cells and are important in the manufacture of ribosomes, tiny machines that synthesize the proteins in the cell. However, SNORD116 (and SNORD115) seem to be different. They are most strongly expressed in the brain and have not yet been found to function in ribosome synthesis.
Many diseases start with small deficiencies in the genome that ultimately cause serious health problems - as a small engine defect will ultimately cause a vehicle breakdown. Understanding of the first steps, and the actual function of the defective component, are needed for early interventions. In this project we are using methods that are well established in our lab to identify those early steps. We will create a wide picture of RNA-RNA and RNA-protein interactions for SNHG14-derived ncRNAs during the development of brain cells, with a focus on SNORD116. In the initial project we discovered that mutant cell lines specifically lacking these ncRNA show restricted changes in the levels of other RNAs and proteins during neuronal development. These results are being published. We are now identifying directly interacting RNA and protein partners, and will test specific hypotheses for the molecular basis of these changes. In addition, we will investigate whether we can activate expression of an intact, but silenced, copy of the SNORD116 region that is present in everyone with PWS.  
The applicants are RNA-biologists, who bring insights and techniques to understand changes in neuronal RNA metabolism that ultimately lead to PWS. We expect to make important discoveries about how PWS related ncRNAs, particularly SNORD116, are regulated and function. We anticipate that neurobiologists will subsequently apply this basic understanding towards the development of molecular treatments, e.g. based on RNA therapeutics