Project description: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. Accordingly, brains of affected patients reveal aggregate-associated sequestration and depletion of the tRNA-LC as well as accumulation of aberrant tRNA species.
Project description:RTP801/REDD1 is a stress-responsive protein overexpressed in neurodegenerative diseases such as Alzheimer’s disease (AD) that contributes to cognitive deficits and neuroinflammation. Here we found that RTP801 interacts with HSPC117, DDX1, and CGI-99, three members of the tRNA ligase complex (tRNA-LC), which ligates the excised exons of intron-containing tRNAs and the mRNA exons of the transcription factor XBP1 during the unfolded protein response (UPR). We also found that RTP801 modulates the mRNA ligase activity of the complex in vitro, since RTP801 knockdown promoted XBP1 splicing and the expression of its transcriptional target, SEC24D. On the contrary, RTP801 overexpression inhibited the splicing of XBP1. In this line, in human AD postmortem hippocampal samples, where RTP801 protein levels are upregulated, we found that XBP1 splicing dramatically decreased. In the 5xFAD mouse model of AD, silencing RTP801 expression in hippocampal neurons promoted Xbp1 splicing and prevented the accumulation of intron-containing pre-tRNAs. Finally, the tRNA-enriched fraction obtained from 5xFAD mice promoted abnormal dendritic arborization in cultured hippocampal neurons, and RTP801 silencing in the source neurons prevented this phenotype. Altogether, these results show that elevated RTP801 impairs RNA processing in vitro and in vivo, in the context of AD and suggest that RTP801 inhibition could be a promising therapeutic approach.
Project description:Chemical cross-linking coupled to mass spectrometry was used to study two tRNA ligase complexes, one consisting of subunits RTCB, DDX1, CGI-99, FAM98B and Ashwin (“full tRLC”) and one lacking Ashwin (“core tRLC”). Cross-linking was performed using the homobifunctional, noncleavable reagent, disuccinimidyl suberate (DSS).
Project description:Transfer RNAs (tRNAs) are traditionally known for their role in protein translation, yet recent discoveries highlight their broader functions in gene regulation, particularly through tRNA-derived small RNAs (tDRs). Studies have shown the singular importance of one unique ArgUCU tRNA isodecoder in mouse neural development, yet potential function(s) of tDRs derived from this and all other tRNAs remain largely unexplored in early human brain development. In this study, we employed cerebral cortical organoid models and AlkB-facilitated RNA methylation sequencing (ARM-seq) to profile tDRs across distinct stages of early human cerebral cortex development. Our analysis reveals dynamic expression patterns of diverse tDR groups derived from a wide range of isodecoders, with several distinct groups showing neural-specific expression. Computational analyses of these tDRs shows biased sequence motifs in over-represented tRNAs that are enriched with particular RNA modifications, giving initial clues to traits that change within the pool of tDRs during neural development. This expanded catalog of tDRs provides a framework for future studies on tRNA function in brain development and offers a deeper understanding of the complexity of tDR dynamics in neural differentiation.
Project description:The goal of this study was to determine the state of the tRNA transcriptome in Brain tissue of Mus Musculus (Mouse). This includes expression data of mature tRNAs and tRNA fragments (tRFs), as well as associated modification states of these RNAs assessed using mismatching percentages from sequencing data.
Project description:we investigated the role of bioactive molecules secreted by HER2+ BC cells in BBB dysfunction during the formation of the pre-metastatic niche before the onset of BrM. We demonstrate that systemic signaling derived from brain metastatic HER2+ primary tumors instigates BBB dysfunction