Biology subjects

Akeda, Y.

Publications and source records attributed to Akeda, Y..

4 recordsLinked to original sources

bioRxiv2026

Periodontal pathogen-derived extracellular vesicles promote EGFR-dependent malignant traits in human pancreatic cancer cells

Extracellular vesicles (EVs) produced by periodontopathic bacteria have been implicated in systemic diseases, yet their mechanistic impact on pancreatic cancer (PAC) cell behavior remains poorly defined. Here, we show that EVs derived from Aggregatibacter actinomycetemcomitans (Aa), but not from Porphyromonas gingivalis or Fusobacterium nucleatum, robustly induce epithelial-mesenchymal transition (EMT), migration, and invasion in human PAC cells. These effects require the Aa genotoxin cytolethal distending toxin (Cdt), which is selectively packaged into Aa-derived EVs and efficiently delivered to host cells. EV-associated Cdt induces DNA damage, triggers a senescence-like transcriptional program, increases EGF sensitivity, and activates the EGFR-ERK/Akt signaling axis independently of TGF{beta} signaling, thereby promoting malignant traits in vitro. Notably, these responses occur in human but not murine PAC cells, revealing species-specific susceptibility to bacterial genotoxins. Together, these findings reveal a previously unrecognized cross-kingdom mechanism by which periodontopathic bacterial EVs promote metastatic traits in human pancreatic cancer cells through Cdt-mediated DNA damage and EGFR-ERK/Akt signaling.

microbiology↗

bioRxiv2025

Oligomeric coiled-coil adhesins that drive chain-like adhesion diversify surface colonization strategies in Shiga toxin-producing Escherichia coli

Bacteria frequently colonize host and environmental surfaces under fluid flow. Chain-like adherence pattern (CLAP) is an EibG-mediated surface colonization phenotype of certain Shiga toxin-producing Escherichia coli (STEC) that lack the locus of enterocyte effacement (LEE). EibG, an immunoglobulin-binding oligomeric coiled-coil adhesin, drives CLAP, but the temporal dynamics and genetic diversity underlying chain formation remain unclear. Here, we use live-cell time-lapse imaging to show that chains arise from single cells that elongate and divide without separation. Under flow, chains resist detachment and undergo shear-dependent fragmentation at cell-cell junctions, releasing viable clonal units that disperse downstream. Comparative genomics reveals substantial diversity among EibG-related adhesins and identifies distinct lineages, including chain-like adhesins (cla) that mediate CLAP while lacking IgG binding. Screening of 1,354 LEE-negative STEC genomes from England shows that claB is present in 95.6% of strains from major LEE-negative STEC serotypes, highlighting its epidemiological prevalence. Targeted mutagenesis demonstrates that chain formation and IgG binding are mediated by distinct structural domains, revealing the modular functional architecture of these adhesins. In a mouse infection model, deletion of eibG reduced lethality, indicating that EibG contributes to virulence. Collectively, these findings establish CLAP as a dynamic, surface-associated strategy of LEE-negative STEC and reveal previously unrecognized diversification among adhesins that drive this behavior.

microbiology↗

bioRxiv2025

Genome-scale dissection of phase-variable gene function in Campylobacter jejuni using a stabilized phasotype library

Phase variation (PV) enables bacterial pathogens to rapidly alter their surface structures through reversible mutations in simple sequence repeats, promoting immune evasion and environmental adaptation. In Campylobacter jejuni, the stochastic nature of PV has hindered the systematic functional analysis of phase-variable genes (PVGs). Here, we introduce PV-GenShift, a genome-scale screening platform built on a genetically stabilized library of phase-locked C. jejuni variants. By fixing the ON/OFF states of 15 PVGs, PV-GenShift enables reproducible, high-resolution analysis of phasotypes, defined as unique ON/OFF combinations across multiple PVGs, under defined selective pressures. Using models of human serum exposure, murine colonization, and chicken gut passage, we identified distinct phasotypes associated with serum resistance and with enrichment during mouse colonization, particularly involving capsular polysaccharide modifications such as O-methyl phosphoramidation and methylation. In contrast, chicken gut passage resulted in heterogeneous ON/OFF shifts without a dominant phasotype. These findings highlight the combinatorial impact of PVG expression states on bacterial adaptation and establish PV-GenShift as a broadly applicable framework for dissecting PV-driven phenotypic diversity. This approach provides a scalable strategy for exploring genotype-phenotype relationships and offers insights relevant to vaccine design and targeted therapeutics. Significance StatementPhase variation generates phenotypic diversity that enables pathogens to evade immunity and adapt to changing environments; however, its random nature has long obscured functional analysis. This study introduces PV-GenShift, a genome-scale platform that stabilizes phase-variable gene expression in Campylobacter jejuni, allowing the systematic identification of gene combinations that influence survival under selective pressures. Using PV-GenShift, we identified phasotypes associated with serum resistance and enrichment during mouse colonization, while chicken passage produced diverse but non-specific shifts. These results demonstrate how combinatorial ON/OFF states of multiple genes shape bacterial adaptation and provide a generalizable strategy for studying phase variation across pathogens, with implications for vaccine design and targeted therapeutics.

microbiology↗

bioRxiv2025

Nutrient Acquisition Drives Edwardsiella tarda Pathogenesis in Necrotizing Soft Tissue Infection

Necrotizing soft tissue infections (NSTIs) are rapidly progressive and life-threatening diseases caused by diverse bacterial pathogens. While classical virulence factors such as toxins and secretion systems have been extensively characterized, the role of metabolic fitness in supporting bacterial survival within the nutrient-restricted host environment remains underexplored. Edwardsiella tarda, a human-pathogenic bacterium implicated in NSTIs, represents an emerging model for studying non-canonical pathogenic strategies. Here, we employed transposon-directed insertion site sequencing (TraDIS) to identify genes critical for E. tarda survival in a murine soft tissue infection model. A genome-wide screen revealed 41 genes significantly depleted during the infection, including those involved in iron and zinc acquisition (fetB, zupT), vitamin biosynthesis (pdxK, cobA), and polyamine metabolism (speB). Functional assays using defined minimal media demonstrated that supplementation with vitamin B6 or putrescine enhanced bacterial growth, validating their contribution to fitness under nutrient-limited conditions. Our findings indicate that E. tarda pathogenesis is driven not solely by classical virulence factors but also by its ability to acquire essential nutrients and adapt metabolically to host-imposed nutritional stress. This study provides the first genome-wide fitness map for E. tarda during soft tissue infection and reveals new targets for therapeutic intervention that disrupt nutrient acquisition systems. These results also emphasize the broader relevance of metabolic adaptation as a determinant of virulence in invasive bacterial infections. IMPORTANCENecrotizing soft tissue infections (NSTIs) are severe, rapidly progressing bacterial infections with high morbidity and mortality. Although classical virulence factors such as toxins have been widely studied, much less is known about how pathogens adapt metabolically to survive within the nutrient-restricted environment in host tissues. This study uses Edwardsiella tarda, an emerging NSTI pathogen, as a model to identify genes required for in vivo fitness using transposon insertion sequencing (TraDIS). By revealing the critical roles of nutrient acquisition and metabolic adaptation, rather than toxin production alone, this work challenges conventional paradigms of bacterial virulence. Our findings suggest that targeting bacterial nutrient acquisition pathways may offer a novel therapeutic approach to control invasive infections. Furthermore, this study provides the first genome-wide fitness map of E. tarda during soft tissue infection, offering a valuable resource for future research into polymicrobial wound infections and host-pathogen nutrient competition.

microbiology↗