NEU-DECO: NEUronal stop codon DECOding as a mechanism to increase proteomic complexity in the brain

Animals are composed of a myriad of cell types with unique transcriptomes and proteomes. Among these, neurons are arguably the most heterogeneous in terms of morphologies and functions.

They achieve this diversity by refining their proteome, mostly through post-transcriptional processes such as RNA editing and alternative splicing.

Another understudied mechanism that can increase proteomic diversity is the extension of protein products by translational stop codon readthrough.

Research from the host lab, as well as others, have in fact shown that Drosophila neurons can decode stop codons as sense codons in a regulated manner and at a much higher rate than other cell types, potentially creating extended protein products of key functional significance.

The goal of this proposal is to investigate the neuronal decoding of stop-codons and to understand: 1) how neurons regulate stop codon readthrough, 2) how it impacts on correct neuronal function, and 3) how universal it is.

First, we will dissect the mechanism and cellular machinery involved in decoding by combining a variety of high-throughput methods with functional studies perturbing trans-acting factors.

Next, we will build a map of stop codon decoding in the fly brain to uncover the hidden variability within neural cell types.

This map will guide further functional studies addressing the contribution of these protein extensions in specific neuronal populations that mediate quantifiable behavioural outputs.

Finally, we will reconstruct the evolutionary history of this non-standard genetic code and test whether their heterologous expression can promote translational readthrough in other systems such as disease-causing premature nonsense mutations in human cells.