Project description:Here, we apply tRNA-seq and YAMAT-seq to profile the expressions of tRFs and tRNAs in plants. We provide a high-quality expression atlas of tRFs and tRNAs in Arabidopsis and rice, and uncover complex tRF population and the dynamic expressions of tRNA genes in plants.
Project description:tRNA related fragments(tRF) and tRNA halves(tiRNA) are novel class of short non-coding RNA derived from tRNAs. Using RNA sequencing, we evaluated the tRFs/tiRNAs expression profiles in relapsed/refractory multiple myeloma and multiple myeloma patients. Bioinformatics analyses indicated that tRFs/tiRNAs may be involved in the progression and drug-resistance of multiple myeloma.
Project description:Background: As couples struggle with infertility and livestock producers wish to rapidly improve genetic merit in their herd, assisted reproductive technologies (ART) have become increasingly popular in human medicine as well as the livestock industry. Utilizing ART can cause an increased risk of congenital overgrowth syndromes, such as Large Offspring Syndrome (LOS) in ruminants. A dysregulation of transcripts has been observed in bovine fetuses with LOS, which is suggested to be a cause of the phenotype. Our recent study identified variations in tRNA expression in LOS individuals, leading us to hypothesize that variations in tRNA expression can influence the availability of their processed regulatory products, tRNA-derived fragments (tRFs). Due to their resemblance in size to microRNAs, studies suggest that tRFs target mRNA transcripts and regulate gene expression. Thus, we have sequenced small RNA isolated from skeletal muscle and liver of day 105 bovine fetuses to elucidate the mechanisms contributing to LOS. Moreover, we have utilized our previously generated tRNA sequencing data to analyze the contribution of tRNA availability to tRF abundance. Results: 22,289 and 7,737 unique tRFs were predicted in the liver and muscle tissue respectively. The greatest number of reads originated from 5′ tRFs in muscle and 5′ halves in liver. In addition, mitochondrial (MT) and nuclear derived tRF expression was tissue-specific with most MT-tRFs and nuclear tRFs derived from LysUUU and iMetCAU in muscle, and AsnGUU and GlyGCC in liver. Despite variation in tRF abundance within treatment groups, we identified differentially expressed (DE) tRFs across Control-AI, ART-Normal, and ART-LOS groups with the most DE tRFs between ART-Normal and ART-LOS groups. Many DE tRFs target transcripts enriched in pathways related to growth and development in the muscle and tumor development in the liver. Finally, we found positive correlation coefficients between tRNA availability and tRF expression in muscle (R = 0.47) and liver (0.6). Conclusion: Our results highlight the dysregulation of tRF expression and its regulatory roles in LOS. These tRFs were found to target both imprinted and non-imprinted genes in muscle as well as genes linked to tumor development in the liver. Furthermore, we found that tRNA transcription is a highly modulated event that plays a part in the biogenesis of tRFs. This study is the first to investigate the relationship between tRNA and tRF expression in combination with ART-induced LOS.
Project description:Parental dietary conditions can influence the metabolic traits of offspring. In mice, paternal consumption of low protein diet alters cholesterol and lipid metabolism of progeny. Here, we examine RNA species expressed in male reproductive tissues of mice. Protein restriction leads to altered levels of multiple small RNAs in mature sperm, as well as throughout the male reproductive tract, with decreased levels of let-7 family members and increased levels of 5â?? fragments of tRNA-Gly isoacceptors. Intriguingly, tRNA fragments are scarce in the testis, but their levels increase in sperm during posttesticular maturation in the epididymis. We find that epididymosomes â?? extracellular vesicles which fuse with sperm during epididymal transit â?? exhibit RNA payloads closely matching those of mature sperm, and can deliver tRNA fragments to immature sperm in vitro both in mouse and in bull. Finally, we show that tRNA-Gly-GCC fragments play a role in repressing genes associated with the endogenous retroelement MERVL, both in ES cells and in preimplantation embryos. Our results shed light on small RNA biogenesis during post-testicular sperm maturation, and link tRNA fragments to regulation of endogenous retroelements active in the early embryo. E14 mESCs were transfected with LNA-containing oligos antisense to tRF-GG or GFP-esiRNA as control, then either total RNA was isolated or 80S ribosomes were isolated from Rnase-digested whole cell lysate, and footprints between 26-32nt were collected for ribosome profiling library construction using a kit-free protocol based on Heyer et al. 2015 NAR.
Project description:To identify tRNA fragments regulated by angiogenin (ANG, Rnase 5), we sequenced 15-50nt small RNAs upon ANG overexpression and ANG knockout.
Project description:Transfer RNA (tRNA)-derived fragments (tRF) are emerging small noncoding (nc) RNAs that, while commonly altered in cancer, have poorly defined roles in tumorigenesis. Here we show that pseudouridylation (Ψ) of a stem-cell-enriched tRF subtype, mTOG, selectively inhibits malignant protein synthesis programs, thereby promoting engraftment and differentiation of myelodysplastic syndrome (MDS) hematopoietic stem and progenitor cells (HSPC). Building on evidence that mTOG-Ψ target the polyadenylate-binding protein cytoplasmic 1 (PABPC1), we employed HDX-MS to reveal critical interactions between mTOG and functional RNA-recognition motif (RRM) domains in PABPC1. Mechanistically, this hinders the recruitment of the translational co-activator PABPC1-interacting protein 1 (PAIP1) and strongly represses translation of transcripts sharing 5’UTR pyrimidine-enriched sequences (PES), including 5’ terminal oligopyrimidine tracts (TOP) that encode protein machinery components, and are frequently altered in cancer. Significantly, mTOG dysregulation leads to aberrantly increased 5’PES mRNA translation in malignant MDS-HSPC and is clinically associated with leukemic transformation and reduced patient survival. Taken together, these results define a critical role for tRF and Ψ in difficult-to-treat subsets of MDS characterized by high risk of progression to acute myeloid leukemia.
Project description:Pseudouridylation (Ψ) is the most abundant and widespread type of RNA epigenetic modification in living organisms; however, the biological role of Ψ remains poorly understood. Here, we show that a Ψ-driven posttranscriptional program steers translation control to impact stem cell commitment during early embryogenesis. Mechanistically, the Ψ ‘writer’ PUS7 modifies and activates a network of tRNA-derived fragments (tRFs) targeting the translation initiation complex. PUS7 inactivation in embryonic stem cells impairs tRF-mediated translational regulation leading to increased protein biosynthesis and abnormal germ layer specification. Remarkably, dysregulation of PUS7 and tRFs in myeloid malignancies associates with altered translation rates, suggesting a role of Ψ in leukemogenesis. Our findings unveil a critical function of Ψ in directing translational control in stem cells with important implications for human disease.
Project description:The human genome encodes hundreds of tRNA genes but their individual contribution to the tRNA pool is not fully understood. Deep sequencing of tRNA transcripts (tRNA-Seq) can estimate tRNA abundance at single gene resolution, but tRNA structures and post-transcriptional modifications impair these analyses. Here we present a bioinformatics strategy to investigate differential tRNA gene expression and use it to compare tRNA-Seq datasets from cultured human cells and human brain. We find that sequencing caveats affect quantitation of only a subset of human tRNA genes. Unexpectedly, we detect several cases where the differences in tRNA expression among samples do not involve variations at the level of isoacceptor tRNA sets (tRNAs charged with the same amino acid but using different anticodons); but rather among tRNA genes within the same isodecoder set (tRNAs having the same anticodon sequence). Because isodecoder tRNAs are functionally equal in terms of genetic translation, their differential expression may be related to non-canonical tRNA functions. We show that several instances of differential tRNA gene expression result in changes in the abundance of tRNA-derived fragments (tRFs) but not of mature tRNAs. Examples of differentially expressed tRFs include: PIWI-associated RNAs, tRFs present in tissue samples but not in cells cultured in vitro, and somatic tissue-specific tRFs. Our data support that differential expression of tRNA genes regulate non-canonical tRNA functions performed by tRFs.
Project description:Arginyltransferase ATE1 mediates posttranslational arginylation that plays key roles in mammalian embryogenesis, cell migration, and normal brain function. The molecular mechanisms of arginylation remain elusive. ATE1 utilizes arginyl-tRNAArg as the donor of Arg, putting this reaction into a direct competition with the protein synthesis machinery. Here, we addressed these questions of ATE1- arginyl-tRNAArg specificity as a potential mechanism enabling this competition in vivo. Using in vitro arginylation assays and ATE1 knockout models, we find that while arginylation is specific to tRNAArg, it is able to utilize short tRNAArg derivatives that bear structural resemblance to tRNA-derived fragments (tRF), a new class of small regulatory non-coding RNAs with poorly characterized but critical functions in vivo. Arginyl-tRFArg can be generated in vitro directly from pre-charged -tRNAArg, and ATE1 is able to utilize these arginyl-tRFArg fragments with similar efficiency as arginyl-tRNAArg. Lack of arginylation in ATE1 knockout cells leads to a decrease in tRFArg generation and a significant increase in the ratio of tRNAArg to tRFArg compared to wild type, suggesting a functional link between tRFArg and arginylation in vivo. We propose that generation of physiologically important tRFs can play a critical role as a switch between protein translation and arginylation in vivo.