Targeting TRMT5 suppresses hepatocellular carcinoma progression via inhibiting the HIF-1α pathways / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Accumulating evidence has confirmed the links between transfer RNA (tRNA) modifications and tumor progression. The present study is the first to explore the role of tRNA methyltransferase 5 (TRMT5), which catalyzes the m1G37 modification of mitochondrial tRNAs in hepatocellular carcinoma (HCC) progression. Here, based on bioinformatics and clinical analyses, we identified that TRMT5 expression was upregulated in HCC, which correlated with poor prognosis. Silencing TRMT5 attenuated HCC proliferation and metastasis both in vivo and in vitro, which may be partially explained by declined extracellular acidification rate (ECAR) and oxygen consumption rate (OCR). Mechanistically, we discovered that knockdown of TRMT5 inactivated the hypoxia-inducible factor-1 (HIF-1) signaling pathway by preventing HIF-1α stability through the enhancement of cellular oxygen content. Moreover, our data indicated that inhibition of TRMT5 sensitized HCC to doxorubicin by adjusting HIF-‍1α. In conclusion, our study revealed that targeting TRMT5 could inhibit HCC progression and increase the susceptibility of tumor cells to chemotherapy drugs. Thus, TRMT5 might be a carcinogenesis candidate gene that could serve as a potential target for HCC therapy.

Effects of tRNA and tRNA-derived Fragments on Skeletal Muscle Development / 中国生物化学与分子生物学报

Skeletal muscle is an important tissue of human and livestock. The study of the muscle development is of great significance for treating muscle diseases and improving livestock meat quality. The process of muscle development is controlled by several myogenic transcription factors and signaling pathways. In addition, recent findings established that several noncoding RNAs play a critical role in the regulation of muscle development such as long non-coding RNA (lncRNA), microRNA (miRNA) and circu- lar RNA (circRNA), etc. The detailed mechanism of muscle development is not well understood. Transfer RNAs (tRNAs) are fundamental components in the translation machinery as an adaptor molecule, and tRNA pool could be differentially exploited to modulate expression of mRNAs. In addition, tRNA can be cleaved into tRNA-derived fragments (tRFs) by a variety of ribonucleases (RNases) upon various stress conditions. Unlike the post-transcriptional regulation of lncRNA and miRNA on muscle development, tRNA has been implicated in various aspects of muscle development. Mitochondria play a central role in a plethora of processes related to the maintenance of muscle cellular homeostasis and genomic integrity. Mitochondrial tRNA(mt-tRNA) gene mutations lead to multiple myopathy because human mitochondrial genome is extremely small. The regulation of tRF is similar to miRNAs in regards to the related physiological processes, but are more conservative than miRNA. It is generally believed that tRF has strong tissue specificity, disease specificity and temporal specificity. Some skeletal muscle-specific tRFs could act posttranscriptionally via RNAi or targeting related genes. However, the tRF-sequencing analysis and functional mechanism of tRF are rarely studied in skeletal muscles. The myopathy caused by mitochondrial tRNA gene mutations are particularly complex, which are one of the challenges to diagnose, treat, or prevent diseases. Compared with other noncoding RNAs, the structural complexity of tRF also brings great challenges to data mining and analysis. In this review, we summarize the formation and function of tRNA and tRF especially in muscle development, which will deepen our understandings of related myopathy, and provide new ideas and directions for the investigation of skeletal muscle.