TET2-mediated tRNA oxidation and its role in hematopoietic cancers

Ten-Eleven Translocation-2 (TET2) is one of the most frequently mutated genes in several hematopoietic malignancies. Its tumor-suppressor function was previously connected with the ability of the TET2 enzyme to oxidize 5-methylcytosine of DNA. Only recently it was shown that TET2 is also capable of oxidizing RNA in vitro and in vivo. It was demonstrated that TET2 oxidizes tRNAs in HEK and mouse embryonic stem cells, and addition of the TET2-oxidized tRNAs was shown to stimulate translation in vitro by an unknown so far mechanism. My research goal is to determine the molecular mechanism underlying the enhanced translation by TET2-modified tRNAs and assess its involvement in the development of hematopoietic cancers. Specifically, with the help of the Swiss Early Postdoc Mobility Fellowship I will determine which tRNAs are oxidized by the TET2 enzyme, and at which positions, using several sequencing approaches. I will test if the TET2-mediated oxidation has an influence on the tertiary structure and stability of modified tRNAs using structural probing, northern blotting, and pulse-chase experiments. To address whether enhanced translation by the TET2-modified tRNAs is codon-specific, I will perform in vitro translation experiments using different reporter mRNAs. Investigation of the newly synthesized proteome under induced depletion of the TET2 enzyme combined with simultaneous transcription repression will allow me to analyze the direct effect of the tRNA oxidation on mammalian protein synthesis. Together, this work will provide a key insight into the molecular function of TET2 enzyme and might reveal a new mechanism of translation regulation relevant for cancer biology.