Project description:C/D box small nucleolar RNAs (snoRNAs) transcribed from the DLK1-DIO3 locus are associated with vascular remodelling and cardiovascular disease. None of these snoRNAs has any known targets yet, except for one, AF357425 in mice and SNORD113-6 in humans. We previously showed that this snoRNA targets mRNAs of the integrin signalling pathway and affects arterial fibroblast function. Here, we aimed to identify whether AF357425/SNORD113-6 can also target small RNAs. We overexpressed or inhibited AF357425 in murine fibroblasts and performed small RNA sequencing. Expression of tRNA fragments (tRFs) was predominantly regulated. Compared to overexpression, AF357425 knockdown led to an overall decrease in tRFs, but with an enrichment in smaller tRFs (<30 nucleotides). We focused on tRNA Leucine anti-codon TAA (tRNALeu(TAA)), that has a conserved predicted binding site for AF357425/SNORD113-6. Adjacent to this site, the tRNA is cleaved to form tRFLeu 47-64, in both primary murine fibroblasts and human arterial fibroblasts. We show that AF357425/SNORD113-6 methylates tRNALeu(TAA) and thereby prevents the formation of tRFLeu 47-64. Exposing fibroblasts to oxidative or hypoxic stress, increased AF357425/SNORD113-6 and tRNALeu(TAA) expression, but AF357425/SNORD113-6 knockdown did not lead to an additional formation of tRFLeu 47-64. Thus, independent of cellular stress, AF357425/SNORD113-6 directs site-specific fragmentation of tRNALeu(TAA) via 2’O-ribose-methylation.
Project description:We combine two experimental high-throughput sequencing methods to identify new 2'-O-methylation sites in human and assign snoRNA guides to sites with previously unknown guides.
Project description:We combine two experimental high-throughput sequencing methods to identify new 2'-O-methylation sites in human and assign snoRNA guides to sites with previously unknown guides.
Project description:small RNA seq form Hek 293 using IonTorrent Sequencing; To assess the general expression of snoRNA derived miRNA like fragments in Hek293. Three independent small RNA libraries were sequenced, aligned and subset for snoRNA (C/D, H/ACA, Small Cajal bodies); analysis of read-length for individual snoRNAs was used to define fragments, then to define coherent processing or degradation of the fragments the location of individual reads over the snoRNA annotation was define.
Project description:The aim is to characterize rat liver fibrosis induced by thioacetamide (TAA). To induce hepatic fibrosis, Male Sprague Dawley rats (9-12 weeks of age and 380-420 g of weight upon arrival, supplied by Beijing Vital River laboratory animal Co., Ltd.) were treated with thioacetamide (TAA). Rat liver samples were collected from five groups of rats at week 1, 2, 4, 8 and 13 after TAA (300 mg/kg) administration three times per week while five control groups receive the same volume of 0.9% normal saline. Four biological replicates were used for each group.
Project description:Comparison of mRNA transcriptome after differential expression of U17 snoRNA. We hypothesiaed that if U17 snoRNA regulates cholesterol homeostasis by modulating the expression of target mRNAs, genes that are differentially expressed by the loss-of-function or gain-of-function of U17 snoRNA would be candidate U17 targets. Results revealed negative regulation of target genes by U17 snoRNA, in which increasing dosage of U17 snoRNA from U17 knockdown to WT to U17 overexpression lead to decreases in target levels. Total RNA were isolated by TRIzol reagent (Invitrogen) from WT, U17 snoRNA KD (ShSnhg3 stable clone), and U17 snoRNA OE (pMDβglobinU17b stable clone) cells grown in LPDS media for 24 hours.
Project description:Osteoarthritis (OA) is a chronic debilitating joint disease which is strongly associated with ageing. OA involves pathological cellular processes in all joint structures and affects articular cartilage integrity, leading to dysfunctional joint articulation. The biomolecular processes that catalyze the disturbances in the articular chondrocyte phenotype leading to OA are poorly understood, and it is expected that a comprehensive understanding of the avenues leading to catabolic changes and disruption of articular chondrocyte homeostasis will provide important cues for future treatments of the condition. Chondrocytes are specialized secretory cells with highly active protein translational machinery, enabling the synthesis and maintenance of the protein-rich cartilage extracellular matrix (ECM). Disturbances in chondrocyte protein translation in cartilage development and OA are connected to mTOR activity, ER stress, unfolded protein response (UPR)and CHOP-mediated apoptosis. These responses change the downstream translational activity of the biosynthesized ribosome. The assembled mammalian ribosome is built from ribosomal RNAs (rRNAs), together with more than 80 different protein subunits. At the heart of the ribosome, the 18S rRNA guides the decoding of the mRNA message, while an ancient ribozyme activity in the 28S rRNA forms the core of the peptidyltransferase center that polymerizes the amino acid sequence encoded by the mRNA into functional proteins. Post-transcriptional maturation of rRNAs is an integral part of the biosynthesis of ribosomes and ribonucleolytic processing of the major 47S rRNA precursor into mature 18S, 5.8S, and 28S rRNAs is rate limiting for ribosome biogenesis. The U3 small nucleolar RNA (snoRNA) is an evolutionarily highly conserved box C/D-class snoRNA which catalyzes the endoribonucleolytic processing of the 5’ external transcribed spacer (ETS) of the 47S pre-rRNA by base complementarity-guided pre-rRNA substrate recognition and plays a crucial role in the maturation of 18S rRNA. Although extensively studied in yeast, it was only recently demonstrated that U3 snoRNA is indispensable for rRNA maturation in human cells. Pathways controlling ribosome activity have previously been described in the regulation of chondrocyte homeostasis. We here now postulate that not only ribosome activity is involved in chondrocyte homeostasis, but that OA pathophysiological situations can also cause alterations in chondrocyte ribosome biogenesis with consequences for cellular protein translation. Since U3 snoRNA-driven rRNA production is rate-limiting in ribosome biogenesis, we hypothesized that the U3 snoRNA is critical for chondrocyte homeostasis. In this study we therefor aimed to determine whether OA pathophysiological conditions interact with chondrocyte U3 snoRNA levels, thereby influencing rRNA levels and chondrocyte translation capacity.
Project description:Velcrin compounds kill cancer cells expressing high levels of phosphodiesterase 3A (PDE3A) and Schlafen family member 12 (SLFN12) by inducing complex formation between these two proteins, but the mechanism of cancer cell killing by the PDE3A–SLFN12 complex is not fully understood. Here, we report that the physiological substrate of SLFN12 RNase is tRNALeu(TAA). SLFN12 selectively digests tRNALeu(TAA), and velcrin treatment promotes the cleavage of tRNALeu(TAA) by inducing PDE3A–SLFN12 complex formation in vitro. We found that distinct sequences in the variable loop and acceptor stem of tRNALeu(TAA) are required for substrate digestion. Velcrin treatment of sensitive cells results in downregulation of tRNALeu(TAA), ribosome pausing at Leu-TTA codons and global inhibition of protein synthesis. Velcrin-induced cleavage of tRNALeu(TAA) by SLFN12 and the concomitant global inhibition of protein synthesis thus define a new mechanism of apoptosis initiation.