Biology subjects

Bowles, I. E.

Publications and source records attributed to Bowles, I. E..

3 recordsLinked to original sources

bioRxiv2026

Targeting tRNA-Arg-TCT-4-1 suppresses cancer cell growth and tumorigenesis

tRNAs play a critical role in protein synthesis, influencing mRNA translation dynamics to shape proteomes. Emerging evidence links dysregulated tRNA activity to cancer progression, with tRNA-Arg-TCT identified as an oncogenic driver when ectopically overexpressed in non-malignant cells. The requirement of endogenous tRNA-Arg-TCT in cancer biology, however, remains untested. Moreover, considering that the tRNA-Arg-TCT family comprises six genes in humans, the importance of an individual tRNA isodecoder in cancer remains unknown. Here, we find elevated levels of tRNA-Arg-TCT-4-1 isodecoder are associated with poor patient prognosis across multiple cancer types. We demonstrate that, using different antisense RNA strategies, specific inhibition of tRNA-Arg-TCT-4-1 suppresses the growth of glioblastoma (GBM) and liposarcoma (LPS) cancer cells. Mechanistically, we find that tRNA-Arg-TCT-4-1 inhibition leads to a codon-biased remodeling of mRNA translation and the proteome, preferentially suppressing expression of growth-promoting genes and pathways encoded by mRNAs enriched in arginine AGA codons. Strikingly, intratumoral delivery of an antisense oligonucleotide (ASO) targeting tRNA-Arg-TCT-4-1 suppresses tumor growth and extends survival in mouse xenograft experiments performed using either a human LPS cell line or a patient-derived soft tissue sarcoma model. This study provides a foundation for targeting tRNA dysregulation as a novel therapeutic approach for cancer. One Sentence SummaryThis study identifies tRNA-Arg-TCT-4-1 as a new anti-cancer therapeutic target and demonstrates that an antisense oligonucleotide (ASO) targeting this tRNA effectively suppresses tumorigenesis and extends survival in mouse xenograft models.

cancer biology↗

bioRxiv2023

A tRNA-specific function for tRNA methyltransferase Trm10 is associated with a new tRNA quality control mechanism in Saccharomyces cerevisiae

In Saccharomyces cerevisiae a single homolog of the tRNA methyltransferase Trm10 performs m1G9 modification on 13 different tRNAs. Here we provide evidence that the m1G9 modification catalyzed by S. cerevisiae Trm10 plays a biologically important role for one of these tRNA substrates, tRNATrp. Overexpression of tRNATrp (and not any of 38 other elongator tRNAs) rescues growth hypersensitivity of the trm10{Delta} strain in the presence of the antitumor drug 5-fluorouracil (5FU). Mature tRNATrp is depleted in trm10{Delta} cells, and its levels are further decreased upon growth in 5FU, while another Trm10 substrate (tRNAGly) is not affected under these conditions. Thus, m1G9 in S. cerevisiae is another example of a tRNA modification that is present on multiple tRNAs but is only essential for the biological function of one of those species. In addition to the effects of m1G9 on mature tRNATrp, precursor tRNATrp species accumulate in the same strains, an effect that is due to at least two distinct mechanisms. The levels of mature tRNATrp are rescued in the trm10{Delta}met22{Delta} strain, consistent with the known role of Met22 in tRNA quality control, where deletion of met22 causes inhibition of 5-3 exonucleases that catalyze tRNA decay. However, none of the known Met22-associated exonucleases appear to be responsible for decay of hypomodified tRNATrp, based on inability of mutants of each enzyme to rescue growth of the trm10{Delta} strain in the presence of 5FU. Thus, the surveillance of tRNATrp appears to constitute a distinct tRNA quality control pathway in S. cerevisiae.

molecular biology↗

bioRxiv2023

tRNA m1G9 modification depends on substrate-specific RNA conformational changes induced by the methyltransferase Trm10

The methyltransferase Trm10 modifies a subset of tRNAs on the base N1 position of the 9th nucleotide in the tRNA core. Trm10 is conserved throughout Eukarya and Archaea, and mutations in the human gene (TRMT10A) have been linked to neurological disorders such as microcephaly and intellectual disability, as well as defects in glucose metabolism. Of the 26 tRNAs in yeast with guanosine at position 9, only 14 are substrates for Trm10. However, no common sequence or other posttranscriptional modifications have been identified among these substrates, suggesting the presence of some other tRNA feature(s) which allow Trm10 to distinguish substrate from nonsubstrate tRNAs. Here, we show that substrate recognition by Saccharomyces cerevisiae Trm10 is dependent on both intrinsic tRNA flexibility and the ability of the enzyme to induce specific tRNA conformational changes upon binding. Using the sensitive RNA structure-probing method SHAPE, conformational changes upon binding to Trm10 in tRNA substrates, but not nonsubstrates, were identified and mapped onto a model of Trm10-bound tRNA. These changes may play an important role in substrate recognition by allowing Trm10 to gain access to the target nucleotide. Our results highlight a novel mechanism of substrate recognition by a conserved tRNA modifying enzyme. Further, these studies reveal a strategy for substrate recognition that may be broadly employed by tRNA-modifying enzymes which must distinguish between structurally similar tRNA species.

biochemistry↗