Project description:To detect the modifed bases in SINEUP RNA, we compared chemically modified in vitro transcribed (IVT) SINEUP-GFP RNA and in-cell transcribed (ICT) SINEUP RNA from SINEUP-GFP and sense EGFP co-transfected HEK293T/17 cells. Comparative study of Nanopore direct RNA sequencing data from non-modified and modified IVT samples against the data from ICT SINEUP RNA sample revealed modified k-mers positions in SINEUP RNA in the cell.
Project description:SINEUPs are natural and synthetic antisense long non-coding RNAs (lncRNAs) selectively enhancing target mRNAs translation by increasing their association with polysomes. This activity requires two RNA domains: an embedded inverted SINEB2 element acting as effector domain, and an antisense region, the binding domain, conferring target selectivity. SINEUP technology presents several advantages to treat genetic (haploinsufficiencies) and complex diseases restoring the physiological activity of diseased genes and of compensatory pathways. To streamline these applications to the clinic, a better understanding of the mechanism of action is needed. Here we show that natural mouse SINEUP AS Uchl1 and synthetic human miniSINEUP-DJ-1 are N6-methyladenosine (m6A) modified by METTL3 enzyme. Then, we map m6A-modified sites along SINEUP sequence with Nanopore direct RNA sequencing and a reverse transcription assay. We report that m6A removal from SINEUP RNA causes the depletion of endogenous target mRNA from actively translating polysomes, without altering SINEUP enrichment in ribosomal subunit-associated fractions. These results prove that SINEUP activity requires an m6A-dependent step to enhance translation of target mRNAs, providing a new mechanism for m6A translation regulation and strengthening our knowledge of SINEUP-specific mode of action. Altogether these new findings pave the way to a more effective therapeutic application of this well-defined class of lncRNAs.
Project description:We found novel functional long non-coding RNAs (lncRNAs) that contain a SINE element, and which up-regulate the translation of target mRNA, named SINEUPs. To investigate the network of translational regulation, we focused on the sub-cellular distribution of target mRNAs and SINEUP RNAs and SINEUP RNA binding proteins (RBPs). We identified PTBP1 and HNRNPK as essential RBPs. These proteins contributed to SINEUP RNA sub-cellular distribution and to assembly of translational initiation complexes, leading to enhancement of the target mRNA translation. To prove the SINEUP RBPs binding regions on SINEUP-GFP transcripts, we performed seCLIP; single-end enhanced crosslinking and immunoprecipitation assay to determine the specific binding sites of PTBP1 and HNRNPK on SINEUP-GFP RNA. These findings will promote a better understanding of the mechanisms on the fate of regulatory RNAs implicated in efficient protein translation.
Project description:N6-methyladenosine (m6A) is the most abundant internal messenger (mRNA) modification in mammalian mRNA. This modification is reversible and non-stoichiometric, which potentially adds an additional layer of variety and dynamic control of mRNA metabolism. The m6A-modified mRNA can be selectively recognized by the YTH family “reader” proteins. The preferential binding of m6A-containing mRNA by YTHDF2 is known to reduce the stability of the target transcripts; however, the exact effects of m6A on translation has yet to be elucidated. Here we show that another m6A reader protein, YTHDF1, promotes ribosome loading of its target transcripts. YTHDF1 forms a complex with translation initiation factors to elevate the translation efficiency of its bound mRNA. In a unified mechanism of translation control through m6A, the YTHDF2-mediated decay controls the lifetime of target transcripts; whereas, the YTHDF1-based translation promotion increases the translation efficiency to ensure effective protein production from relatively short-lived transcripts that are marked by m6A. PAR-CLIP and RIP was used to identify YTHDF1 binding sites followed by ribosome profling and RNA seq to assess the consequences of YTHDF1 siRNA knock-down
Project description:Systematically evaluate the global effect of dysregulated m6A regulators on the m6A epitranscriptome in patient tumors, and identify prognostic m6A markers by linking with patients' clinicopathological and outcome information.
Project description:Although internal PolyA RNA modification N6-methyladenosine (m6A) plays essential roles in diverse biological processes, technology to detect precise m6A sites at transcriptome-wide scale is lacking. Here, we discovered that m6A interferes A (Adenine) – U (Uracil) or A-T (Thymidine) pairing. Based on differential hybridization between methylated vs. unmethylated RNAs to a DNA probe, we developed tiling microarray to pinpoint m6A sites in mouse transcriptome. We validated some of the identified sites and provided evidence to suggest that one functional mechanism of m6A is to block small RNA targeting to methylated mRNA. We designed a custom tiling array with to examine the precise location of m6A within meRIP-seq peaks from mouse embryonic stem cells determined in our previous publication (Wang et al., 2014). Each custom two-channel Agilent tiling array harbors 947,952 probes. Each probe is 25 nucleotides (nt), and any two adjacent probes in the genomic coordinate overlap each other by 19 nt. The Cy5 or red channel corresponds to Mettl14 knockout (M14) or DZA mutant mESC cell line, and Cy3 or green channel is associated with wild type cell line treated with scramble hairpin (SCR). Thus, in principle a higher Cy5/Cy3 signal for each probe reflects an increased hybridization to the oligonucleotide due to de-methylation of a particular RNA molecule in M14 or DZA condition relative to the SCR control. Moreover, we employed additional arrays with both channels dedicated for M14 as an external control for technical difference between the Cy5 and Cy3 dye (details below). For each comparison, we have three biological replicates, and therefore there are 9 tiling arrays in total (i.e., 3 arrays for M14 vs SCR, 3 arrays for DZA vs SCR, and 3 arrays for M14 vs M14).
Project description:We show that N6-methyladenosine (m6A), the most abundant internal modification in mRNA/lncRNA with still poorly characterized function, alters RNA structure to facilitate the access of RBM for heterogeneous nuclear ribonucleoprotein C (hnRNP C). We term this mechanism m6A-switch. Through combining PAR-CLIP with Me-RIP, we identify 39,060 m6A-switches among hnRNP C binding sites transcriptome-wide. We show that m6A-methyltransferases METTL3 or METTL14 knockdown decreases hnRNP C binding at 16,582 m6A-switches. Taken together, 2,798 m6A-switches of high confidence are identified to mediate RNA-hnRNP C interactions and affect diverse biological processes including cell cycle regulation. These findings reveal the biological importance of m6A and provide insights into the sophisticated regulation of RNA-RBP interactions through m6A-induced RNA structural remodeling. Measure the m6A methylated hnRNP C binding sites transcriptome-wide by PARCLIP-MeRIP; measure the differential hnRNP C occupancies upon METTL3/METTL14 knockdown by PAR-CLIP; measure RNA abundance and splicing level changes upon HNRNPC, METTL3 and METTL14 knockdown
Project description:To analyze SINEUP RNA secondary structure in living cells, multiple SINEUP RNA and target EGFP mRNA plasmids were transfected in HEK293T/17 cells and icSHAPE libraries were prepared.
Project description:m6A-seq of undifferentiated and differentiated mouse embryonic stem cell m6A-mRNA library for undifferentiated and differentiated mouse embryonic stem cell each having one biological replicate were generated using HiSeq2000 v3 flowcell (Illumina) and sequenced for 100 bases with separate 7 base indexing read in a single lane.