RNA Sequencing of HEK293T cells expressing 15xGly or 99xGly

Protein aggregates are a hallmark of neurodegenerative disease proposed to promote neurotoxicity through a diverse and growing set of mechanisms. Aggregation of polyglycine is specifically implicated in the pathogenesis of an emerging group of neurodegenerative GGC repeat expansion diseases. Here, we find that polyglycine aggregates incorporate endogenous proteins harboring glycine-rich sequences, including FAM98B, a conserved component of the vertebrate tRNA ligase complex. Through sequestration and accelerated proteosome-dependent turnover mediated by the FAM98B glycine-rich intrinsically disordered region (IDR), polyglycine depletes the ligase complex and disrupts tRNA processing.