Biology subjects

Schlee-Guimaraes, T. M.

Publications and source records attributed to Schlee-Guimaraes, T. M..

3 recordsLinked to original sources

bioRxiv2023

mRNA N1-2'O-methylation by CMTR1 affects NVL2 mRNA splicing

Cap0-mRNA is characterized by a 5-5triphosphate-linked N7-methylated guanosine(m7G). In higher eukaryotes, the methyltransferase CMTR1 additionally methylates the 2O-position of the penultimate mRNA nucleotide(N1) ribose (cap1-mRNA). While the m7G cap is essential for mRNA export and translation initiation by the eIF4F complex, the N1-2O-methylation prevents recognition of cap1-mRNA by the antiviral RNA receptors RIG-I and IFIT1, but a function beyond immunotolerance remained elusive. Here, we generated CMTR1-knockout(CMTR1-/-) cells and found that type-I-interferon(IFN-I) treatment resulted in IFIT1-mediated reduction of cell viability and broad mRNA translation. Consequently, stimulation of the antiviral receptor RIG-I in CMTR1-/- cells revealed an IFIT1 dependent dramatic reduction of IFN-I and chemokine protein induction, demonstrating the importance of N1-2O-methylation for antiviral responses. Additionally, IFN-I- and IFIT1-independent effects were observed: CMTR1-/- cells were smaller, divided slower, and exhibited a reduced transcription of mRNAs coding ribosomal proteins (RP), 5TOP-RNA and snoRNA host genes(SNHG). Additionally, proteome and transcriptome analysis revealed that expression of NVL2, an essential factor in ribosome biogenesis, is strongly suppressed by an alternative-splicing event of NVL2 mRNA in CMTR1-/- cells. This reduction could only be rescued by catalytically active CMTR1. Altogether, besides antiviral immunity N1-2O-methylation by CMTR1 has broad effects on cellular physiology and controls splicing of NVL2.

molecular biology↗

bioRxiv2023

hnRNPM and ELAVL1 control type I interferon induction by promoting IRF3 phosphorylation downstream of both cGAS and RIG-I

RIG-I and cGAS are crucial sensors of viral nucleic acids and induce type I IFNs via TBK1/IKK and IRF3. Here, we have identified hnRNPM as a novel positive regulator of IRF3 phosphorylation and type I IFN induction downstream of both cGAS and RIG-I. Combining interactome analysis and genome editing, we further identified ELAVL1 as an immune-relevant interactor of hnRNPM. Depletion of hnRNPM or ELAVL1 impaired type I IFN induction by HSV-1 and SeV. In addition, we found that hnRNPM and ELAVL1 interact with TBK1 and NF-kB p65. Confocal microscopy revealed cytosolic and perinuclear interactions between hnRNPM, ELAVL1, and TBK1. To our knowledge, hnRNPM and ELAVL1 represent the first non-redundant signaling components merging the cGAS-STING and RIG-I-MAVS pathways, thus representing a novel platform that fuels antiviral defense.

immunology↗

bioRxiv2022

RIG-I activation primes and trains innate antiviral immune memory

Adaptive processes of the innate immune system, known as trained immunity (TI), are critical to human health and disease, yet they have not been systematically investigated downstream of antiviral sensing. Here, we elucidate the potential of the antiviral cytosolic RNA receptor retinoic acid-inducible gene I (RIG-I) to train, prime and tolerize the innate immune system. Using a specific RIG-I agonist, we observed that repetitive stimulation enhanced interferon-stimulated gene (ISG) and pro-inflammatory cytokine induction in human primary monocytes, epithelial cells and fibroblasts and afforded non-specific antiviral protection. RNA sequencing revealed broad, cell type-specific transcriptional changes, indicative of priming of ISGs and training of the NF{kappa}B pathway, without measurable tolerization, while ATAC sequencing in monocytes demonstrated chromatin remodeling and enhanced accessibility of key transcription factor-binding motifs such as STAT1. Moreover, while STAT1 signaling was critically required, it was not sufficient to recapitulate RIG-I induced TI. Altogether, our data demonstrate that RIG-I-mediated TI promotes an immunologically alert state with important implications for host defense and the application of RIG-I ligands in anti-infective and anti-tumoral therapies. One Sentence SummaryRIG-I activation trains and primes innate immune response at the cellular level, affording non-specific immune protection by immune and non-immune cells.

immunology↗