Biology subjects

Colas, A.

Publications and source records attributed to Colas, A..

4 recordsLinked to original sources

bioRxiv2026

Role of transposons in the specialization of Botrytis cinerea to grapevine: Insights into small RNAs and a new Starship

While transposable elements (TEs) are recognized as major drivers of fungal genome structure, evidence of their direct involvement in the interaction with host plants and the environment is only beginning to emerge. Retrotransposons can generate small RNA (sRNA) that act through cross-kingdom RNA interference, while giant DNA TEs called Starships carry dozens of cargo genes that enrich the accessory gene compartment of fungal genomes. In the polyphagous pathogen Botrytis cinerea, the Vv3 strain and other strains specialized on grapevine display a specific repertoire of TEs, including the retrotransposons BcCopia4, BcGypsy6, and BcGypsy7. This study first explored the putative role of sRNA generated from these retrotransposons in the interaction between the Vv3 strain and its host of origin, grapevine. Putative targets were identified among the host mRNAs, but predicted cleavage sites could not be experimentally validated. Moreover, Dicer mutants unable to produce retrotransposons-derived sRNA remained fully pathogenic on grapevine, indicating that these sRNAs do not act as virulence factors on this host. In parallel, this study provides an updated RNA-seq-based annotation of the accessory genes of the Vv3 strain, which revealed a new 93 kb-Starship harboring 43 cargo genes, some of which are related to arsenic resistance. A formal genetic approach confirmed that this locus confers resistance to this metalloid. This giant TE, named Ariane, was also detected in additional grapevine-specialized strains resistant to arsenic but not in strains isolated from other hosts such as tomato. In conclusion, this study highlights how a Starship giant transposon shaped the accessory genes compartment of the polyphagous fungus B. cinerea and may have contributed to its adaptation to vine cultivation by conferring resistance to arsenic, a compound widely used in vineyards during the last century. IMPACT STATEMENTFungal genomes contain many families of transposons whose functional role in adaptation to the environment and in biotic interactions remained hidden for a long time. In the grey mold fungus Botrytis cinerea, strains specialized on grapevine, such as Vv3, carry a specific repertoire of transposons which provides a valuable opportunity to investigate their role in niche adaptation. In this study, we first investigated retrotransposon-derived small RNA, previously described as effectors capable of manipulating the immunity of the model plant Arabidopsis thaliana. Although in silico analysis of the specific repertoire of small RNAs of the Vv3 strain suggested that some could target the expression of grapevine genes, a genetic approach demonstrated that they do not play a significant role in virulence on this host. In contrast, this study identified a new transposon, named Ariane, that carries 43 cargo genes and confers a selective advantage to the Vv3 strain. Ariane belongs to a family of giant transposons called Starships, recently discovered in fungi and considered to be responsible for horizontal genes transfers between unrelated species. Ariane was detected only in some B. cinerea strains isolated from grapevine, and a genetic cross showed that it provides these strains with the ability to grow in presence of arsenic. Arsenic was used in vineyards until the beginning of the 21st century to control fungal trunk diseases and insect pests. Therefore, Ariane appears to have played an important role in the adaptation of B. cinerea strains to cultivated grapevine. Overall, these results underline the importance of considering Starships when predicting emergence of resistance to antifungal compounds. DATA SUMMARYThe novel data described in this study, i.e., RNA-Seq data and the Starship element are accessible under NCBI GEO accession GSE327899 and at https://doi.org/10.57745/HYWRNM, respectively. All information related to Botrytis cinerea genomes used in this study are centralized and kept up to date at the Bioinfo Bioger genomic web portal: https://bioinfo.bioger.inrae.fr/portal/genome-portal/. Direct links to individual portals are respectively https://bioinfo.bioger.inrae.fr/portal/genome-portal/3/ for B. cinerea Vv3 genome, https://bioinfo.bioger.inrae.fr/portal/genome-portal/2/ for B. cinerea Sl3 genome, and https://bioinfo.bioger.inrae.fr/portal/genome-portal/4/ for B. cinerea populations isolated on tomato or grapevine. Each portal provides: (i) a centralized access to public genomic resources, including the genome, transposon, and RNA repositories; (ii) a data browser to download the genomic files; (iii) a genome browser that enables visualization of features within their genomic context, along with associated expression data. As a summary, the prior main public B. cinerea genomic accessions and resources used in this study are: GCA_039644125 for VV3 genome, GCA_022560135 for Sl3 genome, GCA_000143535 for B05.10 genome, PRJNA624742 for populations, https://doi.org/10.57745/HYWRNM for transposons, and GSE181592 for small RNAs. Furthermore, table S1 summarizes the list and characteristics of the 64 B. cinerea genomes publicly available to date. The genomic data for Vitis vinifera genome PN40024.v4 used in this study are available at: https://integrape.eu/resources/genes-genomes/genome-accessions/.

genomics↗

bioRxiv2025

Nucleosome stability safeguards cell identity, stress resilience and healthy aging

Nucleosomes are the minimal repeating units of chromatin. Their dynamic assembly and disassembly underpins chromatin organization and genome regulation. However, it remains unclear how intrinsic nucleosome stability contributes to higher-level yet fundamental cellular and organismal properties--such as preservation of cell identity, lineage specification, stress resilience and ultimately healthy aging. To address this, we tested the impact of decreased intrinsic nucleosome stability across multiple cell, tissue and organismal models by introducing histone mutants that weaken histone-histone interactions. While nucleosome instability did not broadly alter global chromatin accessibility, DNA damage, cell proliferation or viability, it impaired lineage-specific gene expression programs, altered lineage specification and activated intrinsic inflammatory and stress pathways in a manner reminiscent of aging in mouse tissues and human cells. Consistently, nucleosome instability accelerated the onset of age-associated transcriptional alterations and functional decline in Caenorhabditis elegans and Drosophila melanogaster, and reduced cellular resilience to exogenous perturbations-- including environmental, epigenetic and mitotic stress--in human cells and Saccharomyces cerevisiae. These cross-species findings identify nucleosome stability as an evolutionarily conserved epigenetic safeguard that preserves cell identity and stress resilience and supports organismal function and healthy aging.

genomics↗

bioRxiv2022

Multiplatform Modeling of Atrial Fibrillation Identifies Phospholamban as Central Regulator of Cardiac Rhythm

Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia in humans, present in > 33 million people worldwide. Although AF is often developed secondary to cardiovascular diseases, endocrine disorders, or lifestyle factors, recent GWAS studies have identified >200 genetic variants that substantially contribute to AF risk. However, it is currently not known how these genetic predispositions contribute to the initiation and/or maintenance of AF-associated phenotypes. In this context, one major barrier to progress is the lack of experimental systems enabling to rapidly explore the function of large cohort of genes on rhythm parameters in models with human atrial relevance. To address these modeling challenges, we have developed a new multi-model platform enabling 1) high-throughput characterization of the role of AF-associated genes on action potential duration and rhythm parameters at the cellular level, using human iPSC-derived atrial-like cardiomyocytes (ACMs), and at the whole organ level, using the Drosophila heart model, and 2) validation of the physiological relevance of our experimental results using computational models of heterogenous human adult atrial myocytes (HAMs) and tissue. As proof of concept, we screened a cohort of 20 AF-associated genes and identified Phospholamban (PLN) loss of function as a top conserved hit that significantly shortens action potential duration in ACMs, HAMs and fly cardiomyocytes. Remarkably, while PLN knock-down (KD) was not sufficient to induce arrhythmia phenotypes, addition of environmental stressors (i.e fibroblasts, {beta}-adrenergic stimulation) to the model systems, led to the robust generation of irregular beat to beat intervals, delayed after depolarizations, and triggered action potentials, as compared to controls. Finally, to delineate the mechanism underlying PLN KD-dependent arrhythmia, we used a logistic regression approach in HAM populations, and predicted that PLN functionally interacts with both NCX (loss of function) and L-type calcium channels (gain of function) to mediate these arrhythmic phenotypes. Consistent with our predictions, co-KD of PLN and NCX in ACMs and flies, led to increased arrhythmic events, while treatment of ACMs with L-type calcium channel inhibitor, verapamil, reverted these phenotypes. In summary, these results collectively demonstrate that our integrated multi-model system approach was successful in identifying and characterizing conserved roles (i.e regulation of Ca2+ homeostasis) for AF-associated genes and phenotypes, and thus paves the way for the discovery and molecular delineation of new gene regulatory networks controlling atrial rhythm with application to AF.

pathology↗

bioRxiv2022

Nascent Polypeptide Associated Complex-alpha and Signal Recognition Particle are required for cardiac development and remodeling

Congenital Heart Disease (CHD) is driven by a strong genetic predisposition, yet only a small subset of patients ([~]20%) are diagnosed with a precise genetic cause. Therefore, expanding the pool of genes associated with CHD and establishing the functional relationships between genes can assemble a more comprehensive genetic network to better understand cardiac development and pathogenesis. In our studies, we identified protein biogenesis cofactors Nascent polypeptide Associated Complex (NAC) and Signal Recognition Particle (SRP) that bind disparate subsets of emerging nascent polypeptides at the ribosome exit site to direct polypeptide fates, as novel regulators of cell differentiation and cardiac morphogenesis. Knockdown (KD) of the alpha- (Nac) or beta- subunit (bicaudal, bic) of NAC in the developing Drosophila heart led to disruption of cardiac remodeling during pupal stages resulting in an adult fly with no heart. Heart loss was rescued by combined KD of Nac with the Hox gene Abd-B. Consistent with a central role for this interaction in the regulation of cardiogenesis, KD of Nac in Cardiac Progenitors derived from human iPSCs impaired cardiac differentiation while co-KD with mammalian Hox genes HOXC12 and HOXD12 rescued this phenotype. The effect of Nac KD on the fly heart was temporally regulated, in that KD in embryo or in pupae caused only a partial loss of the heart, whereas KD during both stages led to heart loss similar to continuous KD throughout life. This suggests that Nac KD already in the embryo may reprogram cells leading to aberrant cardiac remodeling during pupal stages. Lastly, KD of several SRP subunits individually in the fly heart produced a range of cardiac phenotypes that targeted specific segments and cell types, indicating spatially regulated activities of SRP components in the heart. Together, these data suggest that despite NAC and SRP ubiquitous presence, they displayed spatially and temporally fine-tuned activities for proper cardiac morphogenesis. Nacs interaction with cardiac-specific Hox gene functions builds upon the novel role of this pathway and expands our understanding of the complex genetic networks involved in cardiac development and pathogenesis.

developmental biology↗