Project description:N6-methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as a new mammalian demethylase that oxidatively removes the m6A modification in mRNA in vitro and inside cells. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1552 differentially expressed genes which cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. We show that Alkbh5-deficiency impacts the expression levels of some of these mRNAs, supporting the observed phenotype. The discovery of this new RNA demethylase strongly suggests that the reversible m6A modification plays fundamental and broad functions in mammalian cells. RNA-seq in two cell types
Project description:N6-Methyladenosine (m6A) modification has been found to play important roles in diverse pathogen infections and host responses, here we report host m6A mRNA transcriptome profiles regulated by the infections of two strains of malaria parasite Plasmodium yoelii (N67 and N67C). We showed that malaria infection can regulate host m6A mRNA modification and reprogram host m6A mRNA methylome by mediating corresponding m6A catalytic enzyme levels. Our data suggested m6A modification as a significant transcriptome-wide mark during host-malaria interactions.
Project description:N6-methyladenosine (m6A) has been recently identified as a conserved epitranscriptomic modification of eukaryotic mRNAs, but its features, regulatory mechanisms, and functions in cell reprogramming are largely unknown. Here, we report m6A modification profiles in the mRNA transcriptomes of four cell types with different degrees of pluripotency. Comparative analysis reveals several features of m6A, especially gene- and cell-type-specific m6A mRNA modifications. We also show that microRNAs (miRNAs) regulate m6A modification via a sequence pairing mechanism. Manipulation of miRNA expression or sequences alters m6A modification levels through modulating the binding of METTL3 methyltransferase to mRNAs containing miRNA targeting sites. Increased m6A abundance promotes the reprogramming of mouse embryonic fibroblasts (MEFs) to pluripotent stem cells; conversely, reduced m6A levels impede reprogramming. Our results therefore uncover a role for miRNAs in regulating m6A formation of mRNAs and provide a foundation for future functional studies of m6A modification in cell reprogramming. m6A-seq in ESC, iPSC, NSC and sertoli cells.
Project description:We hypothesized that the trophoblast secretes anti-angiogenic factors, which increase in late pregnancy to limit angiogenesis. Therefore, we determined the paracrine effect of primary human trophoblasts from early versus late pregnancy on the angiogenic potential of isolated feto-placental endothelial cells. We found that the expression and secretion of anti-angiogenic factors differs in early vs late pregnancy, and differentially affects feto-placental angiogenesis.
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification found in mammalian messenger and non-coding RNAs. The discoveries of functionally significant demethylases that reverse this methylation as well as the recently revealed m6A distributions in mammalian transcriptomes strongly indicate regulatory functions of this modification. Here we report the identification and characterization of the mammalian nuclear RNA N6-adenosine methyltransferase core (RNMTC) complex. Besides METTL3, a methyltransferase which was the only known component of RNMTC in the past, we discovered that a previously uncharacterized methyltransferase, METTL14, exhibits a N6-adenosine methyltransferase activity higher than METTL3. Together with WTAP, the third component that dramatically affects the cellular m6A level, these three proteins form the core complex that orchestrates m6A deposition on mammalian nuclear RNA. Biochemistry assays, imaging experiments, as well as transcriptome-wide analyses of the binding sites and their effects on m6A methylation support methylation function and reveal new insights of RNMTC. PAR-CLIP and m6A-seq in HeLa cells
Project description:N6-methyladenosine (m6A) represents the most prevalent internal modification on messenger RNA, and requires a multicomponent m6A methyltransferase complex in mammals. How their plant counterparts determine the global m6A modification landscape and its molecular link to plant development remain elusive. Here we show that FKBP12 INTERACTING PROTEIN 37 KD (FIP37) is a core component of the m6A methyltransferase complex, which underlies control of shoot stem cell fate in Arabidopsis. The mutants lacking FIP37 exhibit massive overproliferation of shoot meristems and a transcriptome-wide loss of m6A RNA modifications. We further demonstrate that FIP37 mediates m6A RNA modification on key shoot meristem genes inversely correlated with their mRNA stability, thus confining their transcript levels to prevent shoot meristem overproliferation. Our results suggest an indispensable role of FIP37 in mediating m6A mRNA modification, which is required for maintaining the shoot meristem as a renewable source for continuously producing all aerial organs in plants. m6A-seq in Arabidopsis thaliana (Col-0) wild-type and fip37-4 LEC1:FIP37, two replicates for each sample
Project description:To further understand the relationship between the level of gene expression and protein translation in human placenta, we focused on N6-methyladenosine: m6A, which is a methylation modification of mRNA acting as a post-transcriptional regulation which has drawn attention in recent years. It is said that m6A affects the fate of mRNA. In addition, it is thought that m6A affects gene expression in the placenta of preeclampsia which is a representative disease of perinatal period and fetal growth abnormality, and the placentas of children who were small for date (SFD) or heavy for date (HFD) were studied in addition to appropriate for date (AFD) preganancies. The SFD placentas contained half of the cases with PE. HEK293T cell was used to confirm the experimental system. PolyA RNA was purified from each tissue and cell, and libraries were prepared from immunoprecipitated (IP) samples using anti-m6A antibody and input samples, and sequenced with Hiseq 1500/2500 and RNAseq was carried out.
Project description:N6-methyladenosine (m6A) represents the most prevalent internal modification on messenger RNA, and requires a multicomponent m6A methyltransferase complex in mammals. How their plant counterparts determine the global m6A modification landscape and its molecular link to plant development remain elusive. Here we show that FKBP12 INTERACTING PROTEIN 37 KD (FIP37) is a core component of the m6A methyltransferase complex, which underlies control of shoot stem cell fate in Arabidopsis. The mutants lacking FIP37 exhibit massive overproliferation of shoot meristems and a transcriptome-wide loss of m6A RNA modifications. We further demonstrate that FIP37 mediates m6A RNA modification on key shoot meristem genes inversely correlated with their mRNA stability, thus confining their transcript levels to prevent shoot meristem overproliferation. Our results suggest an indispensable role of FIP37 in mediating m6A mRNA modification, which is required for maintaining the shoot meristem as a renewable source for continuously producing all aerial organs in plants. RNA-seq in Arabidopsis thaliana (Col-0) wild-type and fip37-4 LEC1:FIP37, three replicates for each sample
Project description:N6-methyladenosine (m6A) is the most prevalent modification in eukaryotic mRNA and potential regulatory functions of m6A have been shown by mapping the RNA m6A modification landscape. M6A modification in active gene regulation manifests itself as altered methylation profiles. However, the profiling of m6A modification and its potential role in preeclampsia (PE) has not yet been studied. In this work, placental samples were collected from PE and control patients. MeRIP-seq was performed to identify differences in m6A methylatio. Altered peaks of m6A-modified transcripts were primarily associated with nitrogen compound metabolic process, positive regulation of vascular-associated smooth muscle cell migration, and endoplasmic reticulum organisation. The m6A hyper-methylated genes of Wnt/β-catenin signalling pathway, mTOR signalling pathway, and several cancer-related pathways may contribute to PE. Our data provide novel information regarding m6A modification alterations in PE and help our understanding of the pathogenesis of PE.
Project description:RNA modification has emerged as an important layer in the control of gene expression. The N6-methyladenosine (m6A) RNA modification is the most prevalent and influences several processes including pre-mRNA splicing, alternative polyadenylation, mRNA decay and translation. Here, we show that m6A regulates transcription by controlling promoter proximal pause release of RNA Pol II. Our results show that the m6A methyltransferase complex together with the nuclear reader Ythdc1 are recruited to gene promoters. Loss of m6A methyltransferase complex leads to increased levels of promoter proximal pausing of RNA Pol II, decrease in Ser2P occupancy on gene body, and affects nascent RNA transcription. Furthermore, we show that the binding of the complex is Spt6-dependent and can be predicted by collective features, with Pol II and pause factors (GAF and M1BP) binding being the most important. We also demonstrate that tethering Mettl3 to a heterologous gene promoter was sufficient to increase the release of RNAP II from the promoter, and this effect was dependent on its m6A catalytic domain. Collectively our data indicate that m6A RNA feeds back to the transcription machinery via its recruitment to the chromatin, and thus uncovering an important link between epigenetic modification of RNA and transcription.