Project description:Degradation of mRNA containing N6-methyladenosine (m6A) is essential for cell growth, differentiation, and stress responses. Here, we show that m6A markedly alters ribosome dynamics and that these alterations mediate the degradation effect of m6A on mRNA. We find that m6A is a potent inducer of ribosome stalling, and these stalls lead to ribosome collisions that form a unique conformation unlike those seen in other contexts. We find that the degree of ribosome stalling correlates with m6A-mediated mRNA degradation, and increasing the persistence of collided ribosomes correlates with enhanced m6A-mediated mRNA degradation. Ribosome stalling and collision at m6A is followed by recruitment of YTHDF m6A reader proteins to promote mRNA degradation. We show that mechanisms that reduce ribosome stalling and collisions, such as translation suppression during stress, stabilize m6A-mRNAs and increase their abundance, enabling stress responses. Overall, our study reveals the ribosome as the initial m6A sensor for beginning m6A-mRNA degradation.
Project description:N6-methyladenosine (m6A) is the most abundant internal mRNA nucleotide modification in mammals, regulating critical aspects of cell physiology and differentiation. The YTHDF proteins are the primary readers of m6A modifications and exert physiological functions of m6A in the cytosol. Elucidating the regulatory mechanisms of YTHDF proteins is critical to understanding m6A biology. Here, we report a mechanism that protein post-translational modifications control the biological functions of the YTHDF proteins. We find that YTHDF1 and YTHDF3, but not YTHDF2, carry high levels of nutrient-sensing O-GlcNAc modifications. O-GlcNAc modification attenuates the translation promoting function of YTHDF1 and YTHDF3 by blocking their interactions with proteins associated with mRNA translation. We further demonstrate that O-GlcNAc modifications on YTHDF1 and YTHDF2 regulate the assembly, stability, and disassembly of stress granule, facilitating rapid exchange of m6A-modified mRNAs in stress granules for recovery from stress. Therefore, our results discover an important regulatory pathway of YTHDF functions, adding an additional layer of complexity to the post-transcriptional regulation function of mRNA m6A.
Project description:N6-methyladenosine (m6A) is the most abundant mRNA nucleotide modification and regulates critical aspects of cellular physiology and differentiation. m6A is thought to mediate its effects through a complex network of interactions between different m6A sites and three functionally distinct cytoplasmic YTHDF m6A-binding proteins (DF1, DF2, and DF3). In contrast to the prevailing model, we show that DF proteins bind the same m6A-modified mRNAs, rather than different mRNAs. Furthermore, we find that DF proteins do not induce translation in HeLa cells. Instead, the DF paralogs act redundantly to mediate mRNA degradation and cellular differentiation. The ability of DF proteins to regulate stability and differentiation becomes evident only when all three DF paralogs are simultaneously depleted. Our studies reveal a unified model of m6A function in which all m6A-modified mRNAs are subjected to the combined action of the YTHDF proteins in proportion to the number of m6A sites.
Project description:Purpose: The goal of this study is to compare the transcriptome changes between Negative control, UBR5 depleted and MYC depleted HeLa cells Methods: Gene expression profiles of Negative control, UBR5 depleted and MYC depleted HeLa cells were generated by deep sequencing, in triplicate. Results:The data were analyzed, and we sucessfully detected global differences in the gene expression between the given groups. Conclusions: UBR5 depletion induces gene expression changes that are partly overlapping with gene expression changes induced by MYC depletion
Project description:Degradation of mRNA containing N6-methyladenosine (m6A) is essential for cell growth, differentiation, and stress responses. Here, we show that m6A markedly alters ribosome dynamics and that these alterations mediate the degradation effect of m6A on mRNA. We find that m6A is a potent inducer of ribosome stalling, and these stalls lead to ribosome collisions that form a unique conformation unlike those seen in other contexts. We find that the degree of ribosome stalling correlates with m6A-mediated mRNA degradation, and increasing the persistence of collided ribosomes correlates with enhanced m6A-mediated mRNA degradation. Ribosome stalling and collision at m6A is followed by recruitment of YTHDF m6A reader proteins to promote mRNA degradation. We show that mechanisms that reduce ribosome stalling and collisions, such as translation suppression during stress, stabilize m6A-mRNAs and increase their abundance, enabling stress responses. Overall, our study reveals the ribosome as the initial m6A sensor for beginning m6A-mRNA degradation.
Project description:We generated a HeLa cell model of mucopolysaccharidosis IIIB (MPSIIIB) by depleting NAGLU. MPSIIIB-associated cell defects were prominent in NAGLU-depleted cells. We explored alterations of metabolic pathways in NAGLU-depleted cells versus non-depleted control cells by performing gene expression profiling. Exon array transcriptome analysis showed 96 transcripts with increased expression level and 38 transcripts with decreased expression level in NAGLU-depleted versus non-depleted cells.
Project description:We generated a HeLa cell model of mucopolysaccharidosis IIIB (MPSIIIB) by depleting NAGLU. MPSIIIB-associated cell defects were prominent in NAGLU-depleted cells. We explored alterations of metabolic pathways in NAGLU-depleted cells versus non-depleted control cells by performing gene expression profiling. Exon array transcriptome analysis showed 96 transcripts with increased expression level and 38 transcripts with decreased expression level in NAGLU-depleted versus non-depleted cells. Total RNA was extracted from two independent cultures of non-depleted cells and NAGLU-depleted cells. We considered a minimal fold change of 1.5 fold and a corrected P value lower than 0.05.
Project description:To understand the polyadenylation site usage at the transcriptome level before and after CFIm25 depletion, we carried out 3'-seq analysis in control and CFIm25-depleted HeLa cells using 3'-seq kit (Lexogen, 016.24)
Project description:We conducted transcriptome analysis of TFAM-depleted HepG2 cells and HeLa cells as a mitochondrial stress model. We found that mitochondrial dysfunction upregulated unique secretory proteins such as amphiregulin (AREG) and thrombospondin 1 in hepatic cells.