Biology subjects

Dore, G.

Publications and source records attributed to Dore, G..

7 recordsLinked to original sources

bioRxiv2026

A variant rRNA serves as a translational repressor in Plasmodium falciparum

Ribosome composition can vary through differences in associated proteins, post-transcriptional and post-translational modifications. Such heterogeneity enables ribosomes to respond to environmental1 or pathological2,3 conditions, and modulate localized translation4. A long-standing observation has also been the differential expression of variant ribosomal RNA (rRNA) alleles across developmental5-7 or cellular states8-14. Yet how exchanging the catalytic ribosome core could regulate translational outcomes remains unknown. Here, we report the functional characterization of a genomically-encoded, divergent rRNA that serves as a dominant-negative repressor of translation during host-to-vector transmission in the human malaria parasite. This allele only encodes for large subunit rRNAs, lacks ITS2 splicing, yet retains conserved rRNA modification and folding patterns alongside vast expansion segments. The resulting large subunit engages mRNA at translation start sites but appears to elongate inefficiently, likely due to divergences in the peptidyl transferase center obstructing the exit tunnel. Through its precisely timed transcription immediately after transmission, this rRNA represses mRNAs that were highly translated in the human, facilitating the transition of the translational program for mosquito-stage development. Our data identify a repressive ribosome population whose antagonistic function is encoded by an independently evolved, variant rRNA allele, defining the conceptual foundation for an additional layer of inherent translational regulation.

molecular biology↗

bioRxiv2026

MaRNAV-1 infection of Plasmodium vivax is associated with increased parasite transmission and host inflammatory responses

MaRNAV-1 is an RNA virus recently identified in Plasmodium vivax-infected samples, but definitive evidence that it infects the parasite and influences malaria pathogenesis remains unknown. Here, we demonstrate that MaRNAV-1 is an intracellular virus that is present in P. vivax at various stages of its life cycle, including blood, sporozoite, and liver stages. Viral prevalence varied geographically between Cambodian and Ethiopian parasites. MaRNAV-1 presence and load were positively associated with parasite transmission potential, as reflected by increased gametocyte abundance and higher oocyst prevalence and intensity in membrane feeding assays. MaRNAV-1 loads were higher in symptomatic compared to asymptomatic infections, and higher MaRNAV-1 loads were associated with elevated body temperature, independently of parasitemia. MaRNAV-1 infection elicits an antibody response and is associated with dendritic cell activation, a shift from Th2 to a Th1-driven immune response, and an increased frequency of double-negative B cells. Accordingly, MaRNAV-1-infected patients had higher concentrations of circulating cytokines, such as IFN-{gamma}, CXCL10, IL-1RA, and IL-6, independently of parasitemia. Together, these findings demonstrate that MaRNAV-1 is a genuine parasite-infecting virus associated with increased parasite transmission potential and with modulation of clinical outcomes in, and host immune response to, P. vivax infections. Our study broadens the conventional view of host-pathogen interactions in malaria by revealing complex virus-parasite-host relationships.

microbiology↗

bioRxiv2026

First draft genome of the decaploid species, Ludwigiagrandiflora subsp. hexapetala, validated through geneexpression

Invasive species are one of the biggest drivers of species extinction. Ludwigia grandiflora subsp. hexapetala (Lgh) is widely invasive in aquatic ecosystems of Europe, North America, and Japan, and also colonizes emergent freshwater soils, but limited genomic data constrain studies of its invasiveness. Here, we report a draft genome assembly of Lgh, with a total length of 1.487 Gb, in agreement with the genome size estimated by flow cytometry, despite high fragmentation (111,219 contigs; N50 = 13.5 kb) and low sequencing depth (6.5x Illumina, 1.6x Nanopore). In addition, an analysis combining homology and expression data identified 139,095 protein-coding genes. Moreover, several indicators suggest that the observed fragmentation is largely attributable to unassembled repetitive regions. Thus, despite these limitations, this assembly represents the first genome in the Ludwigioideae subfamily and constitutes a valuable resource for gene discovery, functional genomics, phylogenetic reconstruction, and evolutionary analyses across the Onagraceae family.

genomics↗

bioRxiv2025

N6-methyladenosine primes the malaria parasite for transmission

Sudden environmental changes are a recurring challenge for unicellular organisms, but a necessity for many to progress through their lifecycle. To transmit from its human host to mosquito vector, malaria parasites differentiate into male and female, semi-quiescent stages that can re-initiate development within seconds after transmission. Here, we identify the RNA modification N6-methyladenosine (m6A) as the mediator of a rapid, sex-specific, and temperature-sensitive mechanism to restructure protein synthesis during transmission. We find that male parasites maintain high levels of translation during their semi-quiescence that are rapidly repressed following mosquito uptake. This translational shutdown is essential for the continuation of male parasite development and depends on the m6A-binding protein YTH.2. We further show that m6A and YTH.2 are already present prior to transmission, but that their repressive interaction requires a temperature drop accompanying the exit from the human host. Hence, m6A appears to prime the parasite transcriptome and subsequently converts an environmental shift into a rapid translational response.

molecular biology↗

bioRxiv2025

A metabolism-chromatin axis promotes ribosome heterogeneity in the human malaria parasite

The transmission of the most virulent human malaria parasite, Plasmodium falciparum, relies on its survival in the contrasting environments of the human host and mosquito vector. One of the most fascinating adaptations to this lifestyle is the specific silencing of individual rDNA genes in the human host that are de-repressed following host-to-vector transmission. In this study, we defined the epigenetic signatures of rRNA transcription and found that rDNA silencing relies on aerobic glycolysis, the sole energy-generating pathway in the human host. We show that disruption of NAD+ regeneration during lactate fermentation promotes rDNA de-repression and identify the sirtuin histone deacetylase Sir2a as the mediator between fluctuating NAD+ levels and a functional transcriptional outcome. Hence, rDNA activation appears to be coupled to the metabolic state of the parasite as it transitions from aerobic glycolysis to mitochondrial respiration during host-to-vector transmission.

microbiology↗

bioRxiv2022

Escape From Oncogene-Induced Senescence is Controlled by POU2F2 and Memorized by Chromatin Scars

Although oncogene-induced senescence (OIS) is a potent tumor-suppressor mechanism, recent studies revealed that cells can escape from OIS with features of transformed cells. However, the mechanisms that promote OIS escape remain unclear, and evidence of post-senescent cells in human cancers is missing. Here, we unravel the regulatory mechanisms underlying OIS escape using dynamic multidimensional profiling. We demonstrate a critical role for AP1 and POU2F2 transcription factors for escape from OIS and identify senescence-associated chromatin scars (SACS) as an epigenetic memory of OIS, detectable during colorectal cancer progression. POU2F2 levels are elevated already in precancerous lesions and as cells escape from OIS, and its expression and binding activity to cis-regulatory elements are associated with decreased patient survival. Our results support a model in which POU2F2 exploits a precoded enhancer landscape to promote senescence escape and reveal POU2F2 gene signatures and SACS as valuable biomarkers with diagnostic and prognostic potential.

genomics↗

bioRxiv2019

AP-1 Imprints a Reversible Transcriptional Program of Senescent Cells

Senescent cells play important physiological- and pathophysiological roles in tumor suppression, tissue regeneration, and aging. While select genetic and epigenetic elements crucial for senescence induction were identified, the dynamics, underlying epigenetic mechanisms, and regulatory networks defining senescence competence, induction and maintenance remain poorly understood, precluding a deliberate therapeutic manipulation of these dynamic processes. Here, we show, using dynamic analyses of transcriptome and epigenome profiles, that the epigenetic state of enhancers predetermines their sequential activation during senescence. We demonstrate that activator protein 1 (AP-1) imprints the senescence enhancer landscape effectively regulating transcriptional activities pertinent to the timely execution of the senescence program. We define and validate a hierarchical transcription factor (TF) network model and demonstrate its effectiveness for the design of senescence reprogramming experiments. Together, our findings define the dynamic nature and organizational principles of gene-regulatory elements driving the senescence program and reveal promising inroads for therapeutic manipulation of senescent cells.

genomics↗