mRNA cap regulation in mammalian cell function and fate

Galloway, Alison; Cowling, Victoria H.

doi:10.1016/j.bbagrm.2018.09.011

Cited by 172 publications

(186 citation statements)

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“…While m 6 A m was first identified in mRNA from mammalian cells and viruses in the 70s [27], the enzymes catalyzing m 6 A m modifications, PCIF1/CAPAM and FTO, were only recently identified, and the study of m 6 A m role in mRNA metabolism and cellular function is still in its infancy. Due to its abundance and its strategical location in the cap structure [57], this chemical modification holds an inherent potential in gene expression control. Mauer et al .…”

Section: Discussionmentioning

confidence: 99%

FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell

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Ripoll

Guillorit

et al. 2020

Preprint

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20Cancer stem cells (CSCs) are a small but critical cell population for cancer biology since they display 21 inherent resistance to standard therapies and give rise to metastases. Despite accruing evidence 22 establishing a link between deregulation of epitranscriptome-related players and tumorigenic 23 process, the role of messenger RNA (mRNA) modifications dynamic in the regulation of CSC 24 properties remains poorly understood. Here, we show that the cytoplasmic pool of fat mass and 25 obesity-associated protein (FTO) impedes CSC abilities in colorectal cancer through its m 6 Am (N 6 ,2'-26 O-dimethyladenosine) demethylase activity. While m 6 Am is strategically located next to the m 7 G-27 mRNA cap, its biological function is not well understood and has not been addressed in cancer. Low 28 FTO expression in patient-derived cell lines elevates m 6 Am level in mRNA which results in enhanced 29 in vivo tumorigenicity and chemoresistance. Inhibition of the nuclear m 6 Am methyltransferase, 30 PCIF1/CAPAM, partially reverses this phenotype. FTO-mediated regulation of m 6 Am marking 31 constitutes a novel, reversible pathway controlling CSC abilities that does not involve transcriptome 32 remodeling, but could fine-tune translation efficiency of selected m 6 Am marked transcripts. 33 Altogether, our findings bring to light the first biological function of the m 6 Am modification and its 34 potential adverse consequences for colorectal cancer management. 35 36 Despite significant advances in diagnosis and therapy, colorectal cancer (CRC) remains a major 37 cause of mortality and morbidity worldwide. CRC survival is highly dependent upon early diagnosis. 38 Patients with localized cancer exhibit 70 to 90% 5-year survival. Survival from metastatic cancer 39 plummets to 10%. Metastasis is a multistep process encompassing local infiltration of tumor cells into 40 adjacent tissues, transendothelial migration into vessels, survival in the circulatory system, 41 extravasation, and colonization of secondary organs [1]. This process entails constant reprogramming 42 of gene expression to enable tumor adaptation in different environments, a peculiar trait of cancer 43 stem cells (CSCs). CSC constitute a minor subpopulation of tumor cells endowed with self-renewal and 44 multi-lineage differentiation capacity [2]. The most clinically relevant trait of CSCs is their ability to 45 metastasize and escape from standard chemotherapy [3]. Understanding the molecular mechanisms 46 that participate to the CSC phenotype is critical to designing improved cancer therapeutics. 47 Discovered several decades ago [12-16], the function of m 6 A remained obscure until the identification 55 of the first m 6 A demethylase, the fat mass and obesity-associated protein (FTO) [17]. The marriage of 56 immunochemical approaches with next-generation sequencing (NGS) technologies revealed the 57 unique topology of m 6 A distribution along mRNA. m 6 A is a dynamic reversible chemical modification 58 catalyzed by a protein complex consisting of the methyl...

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Section: Discussionmentioning

confidence: 99%

FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell

Relier

Ripoll

Guillorit

et al. 2020

Preprint

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“…Over recent years, examples have emerged to illustrate the regulation of mRNA cap formation by different signals. These signals regulate the rate and extent of mRNA cap formation, resulting in changes in gene expression [89]. The first described case of regulated capping was c-myc-dependent activation [90].…”

Section: Capping As a Regulatory Step In Gene Expressionmentioning

confidence: 99%

Interplay of mRNA capping and transcription machineries

et al. 2020

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Early stages of transcription from eukaryotic promoters include two principal events: the capping of newly synthesized mRNA and the transition of RNA polymerase II from the preinitiation complex to the productive elongation state. The capping checkpoint model implies that these events are tightly coupled, which is necessary for ensuring the proper capping of newly synthesized mRNA. Recent findings also show that the capping machinery has a wider effect on transcription and the entire gene expression process. The molecular basis of these phenomena is discussed.

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“…Enzymatic modification of the 5'-end of eukaryotic messenger RNA by the addition of a cap structure is a key process that provides protection against nucleases and facilitates the export and translation of mRNA (1)(2)(3)(4). The cap is formed on the first transcribed nucleotide of the pre-mRNA as a result of three consecutive enzymatic reactions: (i) the 5′ end triphosphate of pre-mRNA is hydrolysed to diphosphate by a 5'-triphosphatase; (ii) GMP is added by the RNA guanylyltransferase to create the cap intermediate GpppN and (iii) the RNA guanine-N7 methyltransferase (RNMT) catalyses the transfer of a methyl group from S-adenosylmethionine (AdoMet) to GpppN to create the mature cap, m7GpppN, and byproduct, AdoHcy (S-adenosyl homocysteine) ( Figure 1A) (2).…”

Section: Introductionmentioning

confidence: 99%

Mechanism of allosteric activation of human mRNA cap methyltransferase (RNMT) by RAM: Insights from accelerated molecular dynamics simulations

Bueren-Calabuig

Bage

Cowling

et al. 2019

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The RNA guanine-7 methyltransferase (RNMT) in complex with RNMT-Activating Miniprotein (RAM) catalyses the formation of a N7-methylated guanosine cap structure on the 5' end of nascent RNA polymerase II transcripts. The mRNA cap protects the transcript from exonucleases and recruits capbinding complexes that mediate RNA processing, export and translation. By using microsecond standard and accelerated molecular dynamics simulations, we provide for the first time a detailed molecular mechanism of allosteric regulation of RNMT by RAM. We show that RAM selects the RNMT active site conformations that are optimal for binding of substrates (AdoMet and the cap), thus enhancing their affinity. Furthermore, our results strongly suggest the likely scenario in which the cap binding promotes the subsequent AdoMet binding, consistent with the previously suggested cooperative binding model. By employing the dynamic network and community analyses, we revealed the underlying long-range allosteric networks and paths that are crucial for allosteric regulation by RAM.Our findings complement and explain previous experimental data on RNMT activity. Moreover, this study provides the most complete description of the cap and AdoMet binding poses and interactions within the enzyme's active site. This information is critical for the drug discovery efforts that consider RNMT as a promising anti-cancer target.Recently, we reported the crystal structure of the catalytic domain (residues 165-476) of human RNMT in complex with the RNMT activation domain of RAM (residues 2-45) and AdoHcy (PDB ID: 5E8J) (8). Human RNMT consists of a catalytic domain (residues 121-476), homologous to other eukaryotic cap methyltransferases, and an N-terminal regulatory domain (residues 1-120) that facilitates the recruitment to RNA polymerase II transcription initiation sites (9, 10) and regulates RNMT activity (11). The presence of RAM permitted the stabilization and crystallization of a modular lobe of RNMT (residues 416-456), which was unresolved in previously reported structures of isolated RNMT (PDB IDs: 3BGV, 5E9W). This strongly suggested that the lobe is disordered in the absence of RAM. . The role of the RAM N-terminal region in the RNMT activation was investigated by simulating RNMT in complex with a truncated form of RAM (residues 20 to 45), in which the N-terminal region was removed. apo-RNMT +RAMAll models were prepared with the LEaP utility from the AMBER14 suite of programs (26) using the ff14SB force field (27). The N-terminus of RNMT was capped with an acetyl group (ACE), and the Nand C-termini of RAM were capped with ACE and a methylated amino group (NME), respectively.The geometries of the ligands were refined with Gaussian03 (28) at the HF/6-31G* level. The optimized geometries were used to calculate the electrostatic potential-derived (ESP) charges using the RESP methodology (29), as implemented in the antechamber module in Amber14 (26). The force field parameters for AdoMet were generated with antechamber module, using the general AMBER fo...

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mRNA cap regulation in mammalian cell function and fate

Cited by 172 publications

References 117 publications

FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell

FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell

Interplay of mRNA capping and transcription machineries

Mechanism of allosteric activation of human mRNA cap methyltransferase (RNMT) by RAM: Insights from accelerated molecular dynamics simulations

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mRNA cap regulation in mammalian cell function and fate

Cited by 172 publications

References 117 publications

FTO-mediated cytoplasmic m6Amdemethylation adjusts stem-like properties in colorectal cancer cell

FTO-mediated cytoplasmic m6Amdemethylation adjusts stem-like properties in colorectal cancer cell

Interplay of mRNA capping and transcription machineries

Mechanism of allosteric activation of human mRNA cap methyltransferase (RNMT) by RAM: Insights from accelerated molecular dynamics simulations

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FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell

FTO-mediated cytoplasmic m⁶A_mdemethylation adjusts stem-like properties in colorectal cancer cell