The role of tRNA thiolation in human disease

An evolutionary conserved machinery orchestrates pivotal modifications of a special group of nucleic acid molecules, (t)RNAs, that, to ensure proper translating information from DNA into proteins. One such modification is the addition of sulfur termed thiolation to certain regions of a subgroup of tRNA molecules. This reaction is catalyzed by two enzymes, the cytosolic thiouridylases CTU1 and CTU2. Impaired thiolation affects translation of genomic information into proteins and is detrimental to most organisms. Recently, it has been linked to a rare but severe syndrome in humans, called DREAM-PL, which is caused by loss or mutation of CTU2. Patients with DREAM-PL show dramatic developmental defects including those that are incurable. The cause behind this disease remains unknown, but recent findings in our group suggest a role for tRNA modifiers, including CTU2, in aberrant cell death signaling and/or the ability of cells to form antenna-like structures called cilia, that are important for signaling in development and adulthood. Here, together with our Polish partners, Sebastian Glatt and his team in Krakow, we seek to investigate the consequences of CTU2 loss-of-function at the cellular level by combining genetic engineering, cell biology and innovative proteomics approaches in in vitro model systems. We will assist our partners in analyzing different mutations defined as critical in structural studies on their effect on enzyme function. Further, we will study DREAM-PL patient-derived material to dissect its etiology and try to develop a preclinical model to study this disease in detail. Ultimately, this project will substantiate our understanding on the interplay of tRNA thiolation, cellular homeostasis and its contribution to human pathology. It will also provide groundwork for targeting the tRNA modification machinery as a potential clinical treatment strategy.