UBE3Aren substratuak identifikatzen Angelman sindromearen ingurukoak argitzeko.

Abstract

Angelman syndrome (AS) is a rare neurodevelopmental disease that results from loss of function of the maternal UBE3A gene. UBE3A codes for an E3 ubiquitin ligase, that coordinately with E1 and E2 enzymes, attaches ubiquitin to proteins. Ubiquitination plays a key role in the fate of proteins. For instance, it can target a protein for degradation, relocate the protein within the cell or determine protein-protein interactions. Therefore, considering the relevance of ubiquitination, and the function of UBE3A, it could be anticipated that in the absence of UBE3A, the ubiquitination pattern of its substrates will be inadequate, thus affecting not only proteins, but also cell physiology. Consequently, to understand the aetiology of the neuronal defects in AS patients, it is mandatory to know which the substrates of UBE3A are. With that aim, we compared the proteins that are ubiquitinated in Drosophila flies overexpressing and not overexpressing UBE3A. Briefly, we combined the BioUb strategy developed in our lab with mass spectrometry, to isolate and detect ubiquitinated proteins, respectively. From the hundreds of proteins detected, 79 fulfilled the criteria to be considered as putative UBE3A substrate. One of those proteins was Rpn10, previously reported to be a UBE3A substrate. Additionally, we confirmed MS results indicating that Rngo might be a UBE3A substrate. Moreover, using human cells we proved that human Rngo homolog DDI1 is also a UBE3A substrate. Now we plan to (i) validate more UBE3A substrates, (ii) check whether those proteins are also substrates in human, and (iii) characterize their biological role.