Biology subjects

Lyko, F.

Publications and source records attributed to Lyko, F..

9 recordsLinked to original sources

bioRxiv2026

m6A RNA methylation modulates Zika virus infection by regulating serine proteases in Aedes albopictus

Epitranscriptomic RNA modifications, particularly N6-methyladenosine (mA), have emerged as important regulators of host-virus interctions. However, the role of mA in arbovirus infection within mosquito vectors remains poorly defined. Here, we characterized the mA RNA methylation machinery in Aedes albopictus C6/36 cells and examined its contribution to Zika virus (ZIKV) replication. Arbovirus infection did not significantly alter the transcriptional levels or enzymatic activity of the core mA methyltransferase components METTL3 and METTL14. In contrast, pharmacological inhibition of METTL3 markedly enhanced ZIKV replication, indicating an antiviral role for mA in mosquito cells. Transcriptome-wide analysis of C6/36 cells treated with the METTL3 inhibitor STM2457 revealed extensive changes in gene expression, including the pronounced upregulation of multiple serine proteases, particularly members of the CLIP family. Single-nucleotide-resolution mapping of mA using GLORI-sequencing showed that m6A is absent from Zika virus RNA, but readily detectable in the A. albopictus transcriptome. Data analysis defined key features of the mosquito epitranscriptome and demonstrated that mA modifications are enriched within the coding regions of serine protease transcripts, supporting their direct regulation by mA. Functionally, inhibition of serine protease activity using AEBSF resulted in a significant reduction of ZIKV replication. Together, these findings identify mA RNA methylation as a critical regulator of ZIKV infection in mosquito cells and uncover an epitranscriptomic pathway linking mA-dependent control of serine proteases to vector-virus interactions. Author SummaryMosquito-borne viruses such as Zika virus pose a major threat to global public health. Successful transmission of these viruses depends not only on infection in humans, but also on their ability to replicate efficiently inside mosquito vectors. Chemical modifications of RNA, collectively known as epitranscriptomic marks, have recently emerged as important regulators of gene expression and virus-host interactions. Among these, N6-methyladenosine (m6A) is the most abundant internal RNA modification in eukaryotic cells. While m6A has been extensively studied in mammalian systems, its role in mosquito antiviral responses remains poorly understood. In this study, we investigated how m6A RNA methylation influences Zika virus infection in mosquito cells derived from Aedes albopictus. We found that reducing m6A levels enhances viral replication, indicating that this RNA modification restricts infection in mosquito cells. Notably, Zika virus RNA itself does not contain detectable m6A modifications. Instead, m6A regulates the expression of specific mosquito genes, including a group of serine proteases that influence viral replication. Pharmacological inhibition of these proteases significantly impaired virus growth, identifying them as key downstream effectors. Our findings reveal an antiviral role for m6A in mosquito cells and uncover a previously unrecognized epitranscriptomic pathway that shapes mosquito-virus interactions. Understanding how RNA modifications regulate arbovirus infection in vectors may open new avenues for strategies aimed at limiting virus transmission.

molecular biology↗

bioRxiv2025

The bladder cancer m6A landscape is defined by methylation dilution and 3'-UTR hypermethylation

N6-Methyladenosine (m6A) is the most abundant internal modification of eukaryotic mRNAs and regulates target transcripts throughout the mRNA life cycle. Although changes in m6A have been reported in human cancers, technical limitations have hindered a comprehensive understanding of the cancer-associated m6A landscape. Here, we used GLORI-sequencing to establish the first transcriptome-wide, single-nucleotide resolution maps of m6A in cancer. Differentially methylated transcripts were enriched in oncogenic pathways relevant to UCB. We discovered two key m6A signatures in UCB: a global loss of methylation and a local hypermethylation at 3'-UTRs. Integration of RNA-sequencing data revealed that the global loss resulted from dilution of methylation marks due to increased expression of unmethylated transcripts and decreased expression of highly methylated transcripts. In contrast, local 3'-UTR hypermethylation was associated with the overexpression of VIRMA, a component of the m6A writer complex, which was linked to UCB progression. Our study is the first to describe the m6A epitranscriptomic landscape of cancer at single-base resolution and provides first insights into the processes that generate its characteristic signatures.

cancer biology↗

bioRxiv2021

Time-resolved, integrated analysis of clonal genome evolution in parthenogenetic animals and in cancer

Clonal genome evolution is a key aspect for parthenogenetic species and cancer. While many studies describe precise landscapes of clonal evolution in cancer, few determine the underlying evolutionary parameters from molecular data, and even fewer integrate theory with data. We derived theoretical results linking mutation rate, time, expansion dynamics, and clinical parameters. We then inferred time-resolved estimates of evolutionary parameters from mutation accumulation, mutational signatures and selection. Using this framework, we traced the speciation of the clonally evolving marbled crayfish population to a time window between 1986 and 1990, which is consistent with biological records. We also used our framework to analyze a published dataset of glioblastoma samples, which identified tumor expansion patterns, cell survival at resection, and selective forces as important factors for tumor development. In conclusion, our framework allowed a time-resolved, integrated analysis of key parameters in clonally evolving genomes, and provided novel insights into the evolutionary age of marbled crayfish and the progression of glioblastoma.

evolutionary biology↗

bioRxiv2020

Translational adaptation to heat stress is mediated by 5-methylcytosine RNA modification in Caenorhabditis elegans

Methylation of carbon-5 of cytosines (m5C) is a post-transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5C-methyltransferases have been studied, the impact of the global cytosine-5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5C in RNA, demonstrating that this modification is non-essential. We determined the localisation and enzymatic specificity of m5C sites in RNA in vivo and showed that animals devoid of m5C are sensitive to temperature stress. At the molecular level, we showed that loss of m5C specifically impacts decoding of leucine and proline thus reducing the translation efficiency of transcripts enriched in these amino acids. Finally, we found translation of leucine UUG codons to be the most strongly affected upon heat shock, suggesting a role of m5C tRNA wobble methylation in the adaptation to heat stress.

genetics↗

bioRxiv2020

Physiological properties and tailored feeds to support aquaculture of marbled crayfish in closed systems

The marbled crayfish (Procambarus virginalis) is a recently discovered freshwater crayfish species, which reproduces by apomictic parthenogenesis, resulting in a monoclonal, all-female population. The animals have become a popular source for nutritional protein in Madagascar and are increasingly being considered for commercial aquaculture. However, their potential has remained unclear and there are also significant ecological concerns about their anthropogenic distribution. We show here that the size and weight of marbled crayfish is comparable to commonly farmed freshwater crayfish. Furthermore, chemical analysis revealed a high chitin content in the marbled crayfish exoskeleton, which is a valuable source for the synthesis of chitosan and bioplastics. To allow the further evaluation of the animals in closed aquaculture systems, we developed tailored feeds that revealed an important role of methionine supplementation for animal growth. Additional analysis revealed a feed conversion rate of 1.4, which compares favorably to leading livestock for sustainable food production. Finally, we provide a concept for ecologically safe marbled crayfish aquaculture, based on key physiological characteristics that mitigate the invasive potential of the animals.

physiology↗

bioRxiv2019

Single-cell transcriptomes of the aging human skin reveal loss of fibroblast priming

Fibroblasts are the main dermal cell type and are essential for the architecture and function of human skin. Important differences have been described between fibroblasts localized in distinct dermal layers, and these cells are also known to perform varied functions. However, this phenomenon has not been analyzed comprehensively yet. Here we have used single-cell RNA sequencing to analyze >15,000 cells from a sun-protected area in young and old donors. Our results define four main fibroblast subpopulations that can be spatially localized and functionally distinguished. Importantly, intrinsic aging reduces this fibroblast priming, generates distinct expression patterns of skin aging-associated genes, and substantially reduces the interactions of dermal fibroblasts with other skin cell types. Our work thus provides comprehensive evidence for a functional specialization of human dermal fibroblasts and suggests that the age-related loss of fibroblast priming contributes to human skin aging.

cell biology↗

bioRxiv2019

Epigenetic deregulation of lamina-associated domains in Hutchinson-Gilford Progeria Syndrome

Hutchinson-Gilford Progeria Syndrome (HGPS) is a progeroid disease characterized by the early onset of some classically age-related phenotypes including arthritis, loss of body fat and hair and atherosclerosis. Cells from affected individuals express a mutant version of the nuclear envelope protein Lamin A (termed Progerin) and have previously been shown to exhibit prominent chromatin changes. Here, we identify epigenetic deregulation of lamina-associated domains (LADs) as a central feature in the molecular pathology of HGPS. Using ATAC-see/-seq and Infinium MethylationEPIC BeadChip-mediated DNA methylation profiling, we demonstrate that dermal fibroblasts from HGPS patients exhibit both chromatin accessibility and DNA methylation changes that are enriched in LADs. Importantly, we further show that these epigenetic alterations are associated with HGPS-specific gene expression changes. Together, our results establish a central involvement of LADs in the epigenetic deregulation of HGPS and provide novel insight into the molecular changes associated with the disease.

cell biology↗

bioRxiv2018

Dnmt1 has an essential function despite the absence of CpG DNA methylation in the red flour beetle Tribolium castaneum

Epigenetic mechanisms, such as CpG DNA methylation enable phenotypic plasticity and rapid adaptation to changing environments. CpG DNA methylation is established by DNA methyltransferases (DNMTs), which are well conserved across vertebrates and invertebrates. There are insects with functional DNA methylation despite lacking a complete set of Dnmts. But at least one of the enzymes, DNMT1, appears to be required to maintain an active DNA methylation system. The red flour beetle, Tribolium castaneum, lacks Dnmt3 but possesses Dnmt1 and it has been controversial whether it has a functional DNA methylation system.\n\nUsing whole genome bisulfite sequencing, we did not find any defined patterns of CpG DNA methylation in embryos. Nevertheless, we found Dnmt1 expressed throughout the entire life cycle of the beetle, with mRNA transcripts significantly more abundant in eggs and ovaries. A maternal knockdown of Dnmt1 caused a developmental arrest in offspring embryos.\n\nWe show that Dnmt1 plays an essential role in T. castaneum embryos and that its downregulation leads to an early developmental arrest. This function appears to be unrelated to DNA methylation, since we did not find any evidence for this modification. This strongly suggests an alternative role of this protein.

evolutionary biology↗

bioRxiv2017

Statistically robust methylation calling for whole-transcriptome bisulfite sequencing reveals distinct methylation patterns for mouse RNAs

Cytosine-5 RNA methylation plays an important role in several biologically and pathologically relevant processes. However, owing to methodological limitations, the transcriptome-wide distribution of this mark has remained largely unknown. We previously established RNA bisulfite sequencing as a method for the analysis of RNA cytosine-5 methylation patterns at single-base resolution. More recently, next-generation sequencing has provided opportunities to establish transcriptome-wide maps of this modification. Here we present a computational approach that integrates tailored filtering and data-driven statistical modeling to eliminate many of the artifacts that are known to be associated with bisulfite sequencing. Using RNAs from mouse embryonic stem cells we performed a comprehensive methylation analysis of mouse tRNAs, rRNAs and mRNAs. Our approach identified all known methylation marks in tRNA and two previously unknown but evolutionary conserved marks in 28S rRNA. In addition, mRNAs were found to be very sparsely methylated or not methylated at all. Finally, the tRNA-specific activity of the DNMT2 methyltransferase could be resolved at single-base resolution, which provided important further validation. Our approach can be used to profile cytosine-5 RNA methylation patterns in many experimental contexts and will be important for understanding the function of cytosine-5 RNA methylation in RNA biology and in human disease.

bioinformatics↗