Biology subjects

Rosignoli, S.

Publications and source records attributed to Rosignoli, S..

7 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

Unravelling the role of epigenetic regulators during embryonic development of Rhipicephalus micropolus

Epigenetic modifications are long-lasting changes to the genome that influence a cells transcriptional potential, thereby altering its function. These modifications can trigger adaptive responses that impact protein expression and various cellular processes, including differentiation and growth. The primary epigenetic mechanisms identified to date include DNA and RNA methylation, histone modifications, and microRNA-mediated regulation of gene expression. The intricate crosstalk among these mechanisms makes epigenetics a compelling field for the development of novel control strategies, particularly through the use of epigenetic drugs targeting arthropod vectors such as ticks. In this study, we identified the Rhipicephalus microplus orthologs of canonical histone-modifying enzymes, along with components of the machinery responsible for m5C and 6mA-DNA, and m6A-RNA methylations. We further characterized their transcriptional profiles and enzymatic activities during embryonic development. To explore the functional consequences of epigenetic regulation in R. microplus, we evaluated the effects of various epigenetic inhibitors on the BME26 tick embryonic cell line. Molecular docking simulations were performed to predict the binding mode of these inhibitors to tick enzymes, followed by in vitro assessment of their effects on cell viability and morphology. Tick cells exposed to these inhibitors exhibited phenotypic and molecular alterations. Notably, we observed higher levels of DNA methylation in the mitochondrial genome compared to nuclear DNA. Inhibition of DNA methylation using 5-azacytidine (5-AZA) was associated with increased activity of the mitochondrial electron transport chain and ATP synthesis, but reduced cellular proliferation. Our findings highlight the importance of epigenetic regulation during tick embryogenesis and suggest that targeting these pathways may offer a novel and promising strategy for tick control. HighlightsO_LIR. microplus presents a complete set of epigenetic enzymes that modify histones, DNA and RNA C_LIO_LIEpigenetic regulation is highly dynamic, and functionally significant during R. microplus embryogenesis C_LIO_LIInhibition of DNA methylation leads to overactivation of the mitochondrial electron transport chain C_LI

molecular biology↗

bioRxiv2025

An evolutionarily conserved role for separase in the regulation of nuclear lamins

Separase is a well conserved endopeptidase that facilitates sister chromatid separation at the metaphase-anaphase transition by cleaving cohesins. Beyond its role in chromosome segregation, Separase also participates in various biological processes, including chromatin organization and replication, centrosome disengagement and duplication, cytokinesis, and telomere capping. Here, we report that the loss of Drosophila separase (Sse) function induces significant changes in global protein expression and affects the protein levels of both A/C-type lamin C (LamC) and B-type lamin Dm0 (Dm0). We further demonstrate that SSE physically interacts with lamins and colocalizes with them at the nuclear envelope during interphase. Additionally, loss of SSE activity disrupts nuclear organization in larval muscles and impairs locomotion in adult flies. Notably, similar to SSE in flies, depletion of human separase (ESPL1) in SV40 fibroblasts leads to misshapen nuclei and increased levels of lamin A. Moreover, we show that ESPL1 interacts with lamin A in human fibroblasts, suggesting that the functional interaction between Separase and lamins is evolutionarily conserved across different organisms.

genetics↗

bioRxiv2024

Draft genome of Palmaria palmata and intraspecific genetic variations in the North-East Atlantic

The rhodophyte Palmaria palmata (L.) Weber & Mohr is one of the target species of a growing European seaweed industry due to its high content of protein and essential amino acids which makes it suitable for human food, dietary supplements, and as salmon feed. However, the lack of a published nuclear genome limits phylogenetics analyses and gene function investigations which could help the development of a breeding programme. We present the first draft genome of P. palmata that was obtained with PacBio HiFi long read sequencing with average coverage of 10x, consisting of an assembly of 1.05 Gb, N50=2.75Mb and BUSCO completeness of 72.1%. Additionally, a population study on the whole genome of 33 P. palmata individuals from across the Northern East Atlantic area found three main clusters consistent with their geographic distribution: (1) Denmark and Norway, (2) France and western Ireland, (3) Faroe Islands. All individuals from Northern Ireland share ancestry with western Ireland and Denmark, and some individuals from the Faroe Islands show admixture from Faroe, western Ireland and Northern Ireland. These results represent a fundamental step towards breeding and genetic studies to further explore the vastly unexploited economic potential of Palmaria palmata. Highlights- We report the first draft genome of Palmaria palmata, from PacBio HiFi long reads. - The size of the genome, 1.05 Gb, is among the largest so far among the Rhodophyta. - Busco completeness of 72.1% and contig N50 of 2.75 Mb indicate good quality. - The genomes of 33 more individuals from North Atlantic Europe have been sequenced. - Phylogenetic analysis found three clusters consistent with geographic distribution.

genomics↗

bioRxiv2024

A missense mutation in the gene encoding the Mg-chelatase subunit I leads to a viable pale green line with phenotypic features of potential interest for barley breeding programs

The pale green trait, i.e. reduced chlorophyll content, has been shown to increase the efficiency of photosynthesis and biomass accumulation when photosynthetic microorganisms and tobacco plants are cultivated at high densities. Thus, the hus1 barley mutant is defective in photosystem antenna biogenesis, and exhibits a 50% reduction in leaf chlorophyll content. Nevertheless, its agronomical performance under standard field conditions is comparable to that of the wild-type. This supports the notion that crops can decrease their investment in antenna proteins and chlorophyll biosynthesis without detrimental effects on productivity. Here, we assess the effects of reducing leaf chlorophyll content in barley by altering the chlorophyll biosynthesis pathway (CBP). To this end, we have isolated and characterised the pale green barley mutant xan-h.chli-1, which carries a missense mutation in the Xan-h gene for subunit I of Mg-chelatase (HvCHLI), the first enzyme in the CBP. Intriguingly, xan-h.chli-1 is the only known viable homozygous mutant at the Xan-h locus in barley. The Arg298Lys amino-acid substitution in the ATP-binding cleft causes a slight decrease in HvCHLI protein abundance, and a marked reduction in Mg-chelatase activity. Under controlled growth conditions, mutant plants display reduced accumulation of antenna and photosystem core subunits, together with reduced photosystem II yield relative to wild type under moderate illumination, and consistently higher than wild-type levels at high light intensities. Moreover, the reduced content of leaf chlorophyll is associated with a stable reduction in daily transpiration rate, and slight decreases in total biomass accumulation and water-use efficiency. These traits are reminiscent of phenotypic features of wild barley accessions and landraces that thrive under arid climatic conditions. Overall, our findings make the xan-h.chli-1 allelic variant of potential interest for tailoring barley, and other crop plants, for growth in harsh environments.

plant biology↗

bioRxiv2021

A lineage-specific Exo70 is required for receptor kinase-mediated immunity in barley

In the evolution of land plants, the plant immune system has experienced expansion in immune receptor and signaling pathways. Lineage-specific expansions have been observed in diverse gene families that are potentially involved in immunity, but lack causal association. Here, we show that Rps8-mediated resistance in barley to the fungal pathogen Puccinia striiformis f. sp. tritici (wheat stripe rust) is conferred by a genetic module: LRR-RK and Exo70FX12, which are together necessary and sufficient. The Rps8 LRR-RK is the ortholog of rice extracellular immune receptor Xa21 and Exo70FX12 is a member of the Poales-specific Exo70FX clade. The Exo70FX clade emerged after the divergence of the Bromeliaceae and Poaceae, and comprises from 2 to 75 members in sequenced grasses. These results demonstrate the requirement of a lineage-specific Exo70FX12 in Rps8 LRR-RK immunity and suggest that the Exo70FX clade may have evolved a specialized role in receptor kinase signaling.

plant biology↗

bioRxiv2021

ENHANCED GRAVITROPISM 2 encodes a STERILE ALPHA MOTIVE containing protein that controls root growth angle in barley and wheat

The root growth angle defines how roots grow towards the gravity vector and is among the most important determinants of root system architecture. It controls water uptake capacity, nutrient use efficiency, stress resilience and as a consequence yield of crop plants. We demonstrated that the egt2 (enhanced gravitropism 2) mutant of barley exhibits steeper root growth of seminal and lateral roots and an auxin independent higher responsiveness to gravity compared to wild type plants. We cloned the EGT2 gene by a combination of bulked segregant analysis and whole genome sequencing. Subsequent validation experiments by an independent CRISPR/Cas9 mutant allele demonstrated that egt2 encodes a STERILE ALPHA MOTIF domain containing protein. In situ hybridization experiments illustrated that EGT2 is expressed from the root cap to the elongation zone. Subcellular localization experiments revealed that EGT2 localizes to the nucleus and cytoplasm. We demonstrated the evolutionary conserved role of EGT2 in root growth angle control between barley and wheat by knocking out the EGT2 orthologs in the A and B genomes of tetraploid durum wheat. By combining laser capture microdissection with RNA-seq, we observed that seven expansin genes were transcriptionally downregulated in the elongation zone. This is consistent with a role of EGT2 in this region of the root where the effect of gravity sensing is executed by differential cell elongation. Our findings suggest that EGT2 is an evolutionary conserved regulator of root growth angle in barley and wheat that could be a valuable target for root-based crop improvement strategies in cereals. Significance StatementTo date the potential of utilizing root traits in plant breeding remains largely untapped. In this study we cloned and characterized the ENHANCED GRAVITROPISM2 (EGT2) gene of barley that encodes a STERILE ALPHA MOTIF domain containing protein. We demonstrated that EGT2 is a key gene of root growth angle regulation in response to gravity which is conserved in barley and wheat and could be a promising target for crop improvement in cereals.

plant biology↗