Biology subjects

Zimmer, J.

Publications and source records attributed to Zimmer, J..

At least 19 recordsLinked to original sources

bioRxiv2026

QTL analysis of essential oil, seed shattering, thousand-grain weight and stalk attachment rate in Carum carvi

Caraway (Carum carvi L., 2n = 2x = 20) is a medicinal and aromatic plant of the Apiaceae family valued for its essential oil with the major terpenoids carvone and limonene. While the essential oil content represents an important quality trait, low seed shattering and high thousand-grain weight (TGW) are key determinants of seed yield. As molecular tools remain scarce within Apiaceae breeding beyond carrot, we conducted a QTL mapping for these seed-related traits using two previously established F2 populations (Effective N(P1) = 236; N(P2) = 266). In P1 with the non-shattering maternal parent Rekord, QTL mapping revealed at least one shattering locus on LG03 (PVE: 9.9%). In addition, loci associated with essential oil (LG08, 10.5% PVE) and TGW (LG09, 11.1% PVE) were detected. In P2, we identified six essential-oil loci (LG02-06, LG10; combined PVE: 49.2%), with five loci affecting both carvone and limonene, and one (LG03) exclusively limonene. Additionally, a major QTL for TGW mapped to LG02 (PVE: 15.6%). For stalk attachment rate one minor QTL was detected (LG07, 8.5% PVE), while no QTL co-localized with the major shattering locus. To pave the path towards fine-mapping, we designed and validated 26 diagnostic PACE markers covering five key QTLs.

genetics↗

bioRxiv2026

Electron microscopy reveals water networks inside hydrated cellulose fibers

Cellulose is a highly abundant linear glucose polymer that exists in amorphous and fibrillar forms1-3. Primarily produced by vascular plants but also microbes and tunicates, cellulose predominantly performs architectural functions by stabilizing cell walls, tissues, and multicellular communities4-9. Owing to its association with other cell surface materials, physiological higher-order structures of cellulose have been difficult to obtain. Here, we describe a never-dried tunicate cellulose fibril structure by cryogenic electron microscopy, which resolves a fiber of more than 360 cellulose strands. Our data reveals linear and severely twisted fiber segments that are interspersed with solvent channels. Solid-state NMR analyses and molecular dynamics simulations indicate the presence of structural water molecules that form a network connecting neighboring cellulose chains. Confocal and super-resolution MINFLUX fluorescence imaging using cellulose-specific probes as well as biochemical analyses demonstrate shared surface and material properties of plant and tunicate cellulose fibers. Combined, our data suggest that architectural water molecules may be common features of cellulose fibers and likely other polysaccharide assemblies in their hydrated physiological states.

molecular biology↗

bioRxiv2026

Site-specific processing of phosphoethanolamine cellulose by the BcsZ cellulase reveals stochastic biofilm cellulose modification

Cellulose is a common component of bacterial biofilms where it interacts with other biopolymers to form a 3-dimensional matrix enclosing the bacteria. Synthesized and secreted by the synthase-dependent biosynthesis pathway common to many bacterial exopolysaccharides, its surface exposure depends on the presence of the periplasmic cellulase BcsZ. During export across the periplasm, E. coli and other Enterobacteriaceae modify cellulose with lipid-derived phosphoethanolamine (pEtN). How BcsZ hydrolyzes pEtN-cellulose in the periplasm is unknown and so is the native distribution pattern of pEtN on cellulose. Here, we used carbohydrate synthesis, X-ray crystallography, native mass spectrometry, and super-resolution MINFLUX nanoscopy to delineate the role of BcsZ during cellulose biosynthesis. Crystal structures of BcsZ bound to chemically synthesized pEtN cello-oligosaccharides identify how the enzyme recognizes pEtN-modified glucosyl units. Comparing mono and double substituted cellohexaoses, we identify varying binding poses that are determined by two pEtN coordination sites within the BcsZ catalytic pocket. Combined, our structural analyses reveal an ideal BcsZ cellohexaose ligand containing two pEtN modified units separated by an unmodified cellotriosyl unit. The enzyme binds and hydrolyzes this compound with substantially increased affinity and efficiency. Further, BcsZ digestion of native pEtN cellulose combined with native mass spectrometry analyses reveals the stochastic distribution of pEtN on biofilm cellulose. Additionally, MINFLUX co-localization of BcsZ with other components of the biosynthetic complex demonstrates the random distribution of BcsZ across the periplasm. Our data suggest BcsZ functions independently of the biosynthetic complex to clear mislocalized pEtN cellulose from the periplasm.

biophysics↗

bioRxiv2026

A molecular description of plant cellulose biosynthesis inhibition

Dictating cell growth and morphology, cellulose biosynthesis is intrinsic to plant cell biology. Accordingly, cellulose biosynthesis inhibitors (CBIs) are important herbicides, toxins, and experimental tools. We currently lack mechanistic understanding of CBI activity, preventing engineering of herbicide selectivity and disease immunity. Contrasting classical inhibitors, we unexpectedly identify the unusual Streptomyces phytotoxin thaxtomin A as the only in vitro-active CBI, with unprecedentedly broad-spectrum activity against various cellulose synthase enzymes. High-resolution cryo-electron microscopy reveals that thaxtomin A leverages exotic nitroaromatic chemistry to target a strictly conserved site in cellulose synthases polysaccharide secretion channel. Strikingly, in vitro biosynthesis and biophysical assays demonstrate thaxtomin As near-picomolar efficacy. Plant and algal systems reveal that its global arrest of cellulose biosynthesis produces an osmotically driven crisis in expanding cells. Finally, site-directed mutagenesis generates the first toxin-resistant cellulose synthase. Our results underscore celluloses critical function in plant lifeforms and inform efforts to inhibit related enzymes across kingdoms.

plant biology↗

bioRxiv2026

Strength in Unity: a Dual Strategy to Restore NK Cell Cytotoxicity against Pancreatic Ductal Adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma (PDAC), a condition representing 90% of pancreatic cancers, shows one of the lowest 5-year survival rates across all cancer types. Current therapeutic approaches remain largely inefficient, in part due to the presence of a hostile tumor microenvironment (TME), impeding immune cells infiltration and function. Specifically, Natural Killer (NK) cells from PDAC patients exhibit impaired phenotype and cytotoxic functions. NK cell immunotherapy represents a safe and promising approach to restore NK cell cytotoxicity against PDAC. MethodsWe developed a dual strategy based on i) the re-activation of NK cells through Natural Killer activating multimeric immunotherapeutic complexes (NaMiX) composed of IL-15/IL-15R dimers coupled to anti-NKp46 single-chain variable fragments (scFvs) and ii) the crosslinking of activated NK cells to PDAC cells with a Trispecific Killer Engager (TriKE) targeting NKG2D, NKp30 and the tumor-associated antigen CEA. We evaluated the ability of these constructs to stimulate NK cell functions across BxPC-3 PDAC cell line and patient-derived organoid models and in humanized NSG mice bearing PDAC xenografts. ResultsNaMiX stimulated the activation and cytotoxic functions of NK cells towards pancreatic BxPC-3 cells in vitro while TriKE cross-linked NK cells to BxPC-3 cells. The cytotoxic effects of NaMiX were further enhanced when combined with the crosslinking abilities of TriKE for the killing of NK cell-mediated BxPC-3 spheroid and PDAC patient-derived organoids. In humanized mice bearing BxPC-3 xenografts, NaMiX induced cytotoxic lymphocyte expansion, and increased tumor infiltration of NK cells, while TriKE tended to slow tumor progression. ConclusionsThis proof-of-concept study reports for the first time that activating and engaging NK cells with immunoconjugates are a promising therapeutic avenue for PDAC treatment. Efforts should now focus on the optimization of NK cell therapeutic modalities to favor the infiltration of a high number of NK cells into the tumor.

immunology↗

bioRxiv2025

Insights into substrate binding and utilization by hyaluronan synthase

Hyaluronan (HA), a heteropolysaccharide of alternating N-acetylglucosamine (GlcNAc) and glucuronic acid (GlcA), is an essential component of the vertebrate extracellular matrix. HA biosynthesis proceeds via three evolutionarily convergent reaction mechanisms, catalyzed by the membrane integrated class 1 enzymes that either elongate the non-reducing (NR) or reducing end of HA, as well as the class 2 hyaluronan synthase (HAS), a soluble non-processive enzyme. Class 1-NR HAS, found in both vertebrates and large double-stranded DNA viruses, is monomeric and couples HA polymerization via coordinated transfer of UDP-GlcNAc and UDP-GlcA substrates with the secretion of the nascent HA chain through its own transmembrane channel. How this HAS discriminates between two UDP-sugars using a single active site is a critical, yet unresolved question. Using single-particle cryo-EM, we reveal a two-step process by which the Chlorella virus HAS (CvHAS) recognizes and positions its substrate, UDP-GlcA, for glycosyl transfer. Further, we report greatly diminished turnover of UDP-GlcA in the absence of a primer, distinguishing acceptor free activity toward UDP-GlcNAc. Lastly, prompted by observation of a dodecyl maltoside bound HAS, we demonstrate the utility of non-canonical acceptors in priming of a UDP-GlcA transfer reaction. Altogether, this work clarifies the molecular basis for HAS dual substrate specificity and the role of UDP-GlcA recognition in integrity of HA synthesis.

biophysics↗

bioRxiv2025

Dendritic Architecture Enables de Novo Computation of Salient Motion in the Superior Colliculus

Dendritic architecture plays a crucial role in shaping how neurons extract behaviorally relevant information from sensory inputs. Wide-field neurons in the superior colliculus integrate visual information from the retina to encode cues critical for visually guided orienting behaviors. However, the principles governing how these neurons filter their inputs to generate appropriate responses remain unclear. Using viral tracing, two-photon calcium imaging, and computational modeling, we show that wide-field neurons receive functionally diverse inputs from twelve retinal ganglion cell types, forming a layered, type-specific organization along their dendrites. This structured arrangement allows wide-field neurons to multiplex salient motion cues, selectively amplifying movement and suppressing static features. Computational models reveal that the spatial organization of dendrites and inputs enables the selective extraction of behaviorally relevant stimuli, including de novo computations. Our findings underscore the critical role of dendritic architecture in shaping sensory processing and neural circuit function.

neuroscience↗

bioRxiv2024

Molecular insights into phosphoethanolamine cellulose formation and secretion

Phosphoethanolamine (pEtN) cellulose is a naturally occurring modified cellulose produced by several Enterobacteriaceae. The minimal components of the E. coli cellulose synthase complex include the catalytically active BcsA enzyme, an associated periplasmic semicircle of hexameric BcsB, as well as the outer membrane (OM)-integrated BcsC subunit containing periplasmic tetratricopeptide repeats (TPR). Additional subunits include BcsG, a membrane-anchored periplasmic pEtN transferase associated with BcsA, and BcsZ, a conserved periplasmic cellulase of unknown biological function. While events underlying the synthesis and translocation of cellulose by BcsA are well described, little is known about its pEtN modification and translocation across the cell envelope. We show that the N-terminal cytosolic domain of BcsA positions three copies of BcsG near the nascent cellulose polymer. Further, the terminal subunit of the BcsB semicircle tethers the N-terminus of a single BcsC protein to establish a trans-envelope secretion system. BcsCs TPR motifs bind a putative cello-oligosaccharide near the entrance to its OM pore. Additionally, we show that only the hydrolytic activity of BcsZ but not the subunit itself is necessary for cellulose secretion, suggesting a secretion mechanism based on enzymatic removal of mislocalized cellulose. Lastly, we introduce pEtN modification of cellulose in orthogonal cellulose biosynthetic systems by protein engineering.

biophysics↗

bioRxiv2024

In vitro function, assembly, and interaction of primary cell wall cellulose synthase homotrimers

Plant cell walls contain a meshwork of cellulose fibers embedded into a matrix of other carbohydrate and non-carbohydrate-based biopolymers. This composite material exhibits extraordinary properties, from stretchable and pliable cell boundaries to solid protective shells. Cellulose, a linear glucose polymer, is synthesized and secreted across the plasma membrane by cellulose synthase (CesA), of which plants express multiple isoforms. Different subsets of CesA isoforms are necessary for primary and secondary cell wall biogenesis. Here, we structurally and functionally characterize the Glycine max (soybean) primary cell wall CesAs CesA1, CesA3, and CesA6. The CesA isoforms exhibit robust in vitro catalytic activity. Cryo-electron microscopy analyses reveal their assembly into homotrimeric complexes in vitro in which each CesA protomer forms a cellulose-conducting transmembrane channel with a large lateral opening. Biochemical and co-purification analyses demonstrate that different CesA isoforms interact in vitro, leading to synergistic cellulose biosynthesis. Interactions between CesA trimers are only observed between different CesA isoforms and require the class-specific region (CSR). The CSR forms a hook-shaped extension of CesAs catalytic domain at the cytosolic water-lipid interface. Negative stain and cryo-electron microscopy analyses of mixtures of different CesA isoform trimers reveal their side-by-side arrangement into loose clusters. Our data suggest a model by which CesA homotrimers of different isoforms assemble into cellulose synthase complexes to synthesize and secrete multiple cellulose chains for microfibril formation. Inter-trimer interactions are mediated by fuzzy interactions between their CSR extension.

plant biology↗

bioRxiv2024

Complement-Activating Multimeric Immunotherapeutic Complexes for HER2-breast cancer immunotherapy

BackgroundDirecting selective complement activation towards tumor cells is an attractive strategy to promote their elimination. We have generated Complement-activating Multimeric immunotherapeutic compleXes (CoMiX) that selectively stimulate the alternative pathway using Factor H Related protein 4 (FHR4) or the classical complement pathways using triple Fc dimers on HER2-expressing tumor cells. MethodsWe used the C4bp C-terminal--/{beta}-chain multimerising scaffolds to generate CoMiX-FHR4 and CoMiX-Fc with 2 different VHH anti-HER2, VHH(T) and VHH(P), recognising trastuzumab-or pertuzumab-competing HER2 epitopes, respectively: FHR4/VHH(T), FHR4/VHH(P), VHH(T)/Fc, VHH(P)/Fc. The different CoMiX were compared in vitro for C3b and C5b9 depositions, complement-dependent cytotoxicity, and their ability to activate NK cells and phagocytosis by macrophages using one-way ANOVA and post-hoc Tukeys tests. We further explored their therapeutic efficacy in vivo on human BT474 breast cancer xenografts established in NUDE mice, when used individually or in combination, as compared to trastuzumab or pertuzumab. ResultsFHR4/VHH(T) and FHR4/VHH(P) led to the highest C3b and C5b9 depositions and CDC, both individually and in combinations on BT474 tumor cells (p< 0.0001) surpassing the very low complement activating capacity of trastuzumab and pertuzumab. CoMiX-Fc showed NK cell activation and complement-mediated BT474 phagocytosis by M2 macrophages. In the xenograft model, CoMiX-FHR4 molecules reduced the tumor volume by a factor of 7.33 compared to the PBS control. VHH(T)/Fc had no effect on tumor growth, while VHH(P)/Fc led to a 2.75-times tumor volume reduction that was higher than pertuzumab (p< 0.01). Trastuzumab and its combination with pertuzumab remained the most potent regimen, alone or in combination, to completely inhibit tumor growth. CoMiX-FHR4, CoMiX-Fc and C3b deposition were visualized as soon as one hour after injection resulting in a massive homogeneous complement deposit 6 hours after injection. Interestingly, CoMiX-FHR4 significantly reduced the growth of trastuzumab-resistant cancer cells in contrast to trastuzumab and induced a large NK cell infiltration into the tumor. ConclusionsCoMiX-FHR4 and CoMiX VHH(P)/Fc significantly inhibit tumor growth through complement activation, NK cells infiltration, and phagocytosis by macrophages. CoMiX-FHR4 proteins delay xenograft growth of BT474 cells resistant to trastuzumab and could thus be an attractive approach when resistance to antibody emerges. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSComplement activation represents a substantial part of the overall biological activity of few therapeutic antibodies used in cancer immunotherapy. Factor H-related protein 4 can activate complement by serving as a platform for the assembly of alternative pathway C3 convertase by competing with factor H for C3b binding. We previously showed that multimeric recombinant proteins displaying the FHR4 complement effector moiety and a nanobody anti-HER2 targeting moiety selectively direct the activation of the complement alternative pathway on HER2-expressing tumor cells, leading to subsequent cell destruction through direct cell lysis or through the activation of host effector cells. What this study addsWe used in the current work a novel complement-directed tumor cell distruction strategy in vivo. We showed that CoMiX-FHR4 and CoMiX-Fc (based on triple Fc dimers), targeting HER2-positive breast tumor cells, inhibit tumor growth in a model of BT474 xenograft in NUDE mice by stimulating complement activation, BT474 death, NK cell activation, and phagocytosis of tumor cells by macrophages. CoMiX-FHR4 remain efficient in xenografts of BT474 cells resistant to trastuzumab. How this study might affect research, practice or policyWe demonstrate for the first time that directed complement activation on tumor cells is an alternative to therapeutic antibodies which is particularly promising when resistance to standard-of-care treatment occurs.

immunology↗

bioRxiv2023

Striatum supports fast learning but not memory recall

Animals learn to carry out motor actions in specific sensory contexts to achieve goals. The striatum has been implicated in producing sensory-motor associations, yet its contribution to memory formation or recall is not clear. To investigate the contribution of striatum to these processes, mice were taught to associate a cue, consisting of optogenetic activation of striatum-projecting neurons in visual cortex, with forelimb reaches to access food pellets. As necessary to direct learning, striatal neural activity encoded both the sensory context and outcome of reaching. With training, the rate of cued reaching increased, but brief optogenetic inhibition of striatal activity arrested learning and prevented trial-to-trial improvements in performance. However, the same manipulation did not affect performance improvements already consolidated into short- (within an hour) or long-term (across days) memories. Hence, striatal activity is necessary for trial-to-trial improvements in task performance, leading to plasticity in other brain areas that mediate memory recall.

neuroscience↗

bioRxiv2023

Structural snapshots of hyaluronan formation reveal principles of length control and secretion

Hyaluronan (HA) is an essential component of the vertebrate extracellular matrix. It is a heteropolysaccharide of alternating N-acetylglucosamine (GlcNAc) and glucuronic acid (GlcA) units reaching several megadaltons in healthy tissues. HA is synthesized and secreted in a coupled reaction by HA-synthase (HAS). Here, structural snapshots of HAS provide important insights into HA biosynthesis, from substrate recognition to HA elongation and translocation. We reveal a loop insertion mechanism for substrate binding, monitor the extension of a GlcNAc primer with GlcA, and capture the opening of a secretion channel that coordinates a nascent HA polymer. Further, we identify HA-interacting residues that control HA product lengths. Integrating structural and biochemical analyses, we propose a mechanism for HA length control based on finely tuned enzymatic processivity and catalytic rates.

biophysics↗

bioRxiv2023

Transcription elongation defects link oncogenic splicing factor mutations to targetable alterations in chromatin landscape

Transcription and splicing of pre-messenger RNA are closely coordinated, but how this functional coupling is disrupted in human disease remains unexplored. Here, we investigated the impact of non-synonymous mutations in SF3B1 and U2AF1, two splicing factors commonly mutated in cancer, on transcription. We find that the mutations impair RNA Polymerase II (RNAPII) transcription elongation along gene bodies leading to transcription-replication conflicts, replication stress and altered chromatin organization. This elongation defect is linked to disrupted pre-spliceosome assembly due to impaired protein-protein interactions of mutant SF3B1. Through an unbiased screen, we identified epigenetic factors in the Sin3/HDAC complex, which, when modulated, normalize transcription defects and their downstream effects. Our findings shed light on the mechanisms by which oncogenic mutant spliceosomes impact chromatin organization through their effects on RNAPII transcription elongation and present a rationale for targeting the Sin3/HDAC complex as a potential therapeutic strategy. HIGHLIGHTS- Oncogenic mutations in SF3B1 and U2AF1 cause a gene body RNAPII transcription elongation defect - The elongation defect is linked to impaired assembly of early spliceosome complexes and leads to replication stress and changes to chromatin landscape - RNAPII elongation defects in SF3B1K700E are normalized by modulating epigenetic factors but 3 cryptic splicing events are not reversed - Targeting the Sin3/HDAC pathway to normalize RNAPII elongation defect is a potential therapeutic approach in these disorders GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/530019v3_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@dc6d22org.highwire.dtl.DTLVardef@180f36borg.highwire.dtl.DTLVardef@ed341forg.highwire.dtl.DTLVardef@f8dfb2_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Insights into substrate coordination and glycosyl transfer of poplar cellulose synthase-8

Cellulose is an abundant cell wall component of land plants. It is synthesized from UDP-activated glucose molecules by cellulose synthase, a membrane-integrated processive glycosyltransferase. Cellulose synthase couples the elongation of the cellulose polymer with its translocation across the plasma membrane. Here, we present substrate and product-bound cryogenic electron microscopy structures of the homotrimeric cellulose synthase isoform-8 (CesA8) from hybrid aspen (poplar). UDP-glucose binds to a conserved catalytic pocket adjacent to the entrance to a transmembrane channel. The substrates glucosyl unit is coordinated by conserved residues of the glycosyltransferase domain and amphipathic interface helices. Site-directed mutagenesis of a conserved gating loop capping the active site reveals its critical function for catalytic activity. Molecular dynamics simulations reveal prolonged interactions of the gating loop with the substrate molecule, particularly across its central conserved region. These transient interactions likely facilitate the proper positioning of the substrate molecule for glycosyl transfer and cellulose translocation. HighlightsO_LICryo-EM structures of substrate and product bound poplar cellulose synthase provide insights into substrate selectivity C_LIO_LISite directed mutagenesis signifies a critical function of the gating loop for catalysis C_LIO_LIMolecular dynamics simulations support persistent gating loop - substrate interactions C_LIO_LIGating loop helps in positioning the substrate molecule to facilitate cellulose elongation C_LIO_LIConserved cellulose synthesis substrate binding mechanism across the kingdoms C_LI

biochemistry↗

bioRxiv2022

Natural Killer activating Multimeric Immunotherapeutic compleXes (NaMiX) induce cytotoxic activity and killing of HIV-1 infected cells

HIV-1 persists in viral reservoirs of latently infected CD4+ T cells containing integrated replication-competent viral DNA. Combined Antiretroviral Therapy (cART) does not eradicate HIV-1 reservoirs and treatment interruption will ultimately lead to viral load rebound. HIV-1 infection dramatically reduces the proportion of functional NK cell subsets and increases the expression of the checkpoint inhibitors NKG2A and KIR2DL. In this regard, we developed novel recombinant molecules combining multimers of the IL-15/IL-15R complex with the single-chain fragment variables (scFvs) of NKG2A or KIR2DL, and named them as Natural killer activating Multimeric immunotherapeutic compleXes (NaMiX). NaMiX significantly improved the cytotoxic activity of NK cells against HIV-1 positive ACH-2 cells and resistant Raji cancer cells by increasing their degranulation capacity, release of granzyme B, perforin and IFN-{gamma} expression. Targeting the NKG2A receptor had a stronger effect compared to the targeting of the KIR2DL receptor due to its higher expression on NK cells. In a viral inhibition assay using CD4+ T cells from HIV-1 positive patients under cART, NaMiX initially increased viral replication which was subsequently inhibited by stimulated NK cells. In humanized NSG tg-huIL-15 mice showing functional NK cells, we observed enhanced activation, degranulation and killing by NK cells from the spleen of mice treated with anti-NKG2A NaMiX compared to the cells of control mice previously infected with HIV-1 and treated with cART. Although NaMiX did not delay viral load rebound after treatment interruption in a first attempt, it tend to decrease total HIV-1 DNA in the lungs of the mice. Blocking the inhibitory receptor NKG2A in combination with targeted multimers of IL-15 on NK cells could therefore be a promising immunotherapeutic strategy towards HIV-1 functional cure.

immunology↗

bioRxiv2022

Genomic instability in patients with sex determination defects and germ cell cancer

The ability to transmit genetic information through generations depends on preservation of genome integrity. Genetic abnormalities affect cell differentiation, causing tissue specification defects and cancer. We addressed genomic instability in individuals with Differences of Sex Development (DSD), characterized by gonadal dysgenesis, infertility, high susceptibility for different types of cancer, especially Germ Cell Tumors (GCT), and in men with testicular GCTs. Whole proteome analysis of leukocytes, supported by specific gene expression assessment, and dysgenic gonads characterization, uncovered DNA damage phenotypes with altered innate immune response and autophagy. Further examination of DNA damage response revealed a reliance on deltaTP53, which was compromised by mutations in the transactivation domain in DSD-patients with GCT. Accordingly, drug-induced rescue of DNA damage was achieved by autophagy inhibition but not by stabilization of TP53 in DSD-patients blood in vitro. This study elucidates possibilities for prophylactic treatments of DSD patients as well as new diagnostic approaches of GCT. TeaserDNA damage phenotypes accompany aneuploidy of sex chromosomes and link to infertility and high propensity to germ cell tumor development.

genetics↗

bioRxiv2021

Dietary modulation alters susceptibility to Listeria monocytogenes and Salmonella typhimurium in a gut microbiota-independent manner

Food safety has considerably improved worldwide, yet infections with food-borne human enteric pathogens, such as Listeria spp. and Salmonella spp., still cause numerous hospitalizations and fatalities. Thus, the need to shed more light on the mechanisms of enteropathogenesis is apparent. Since dietary alterations, including fiber deficiency, might impact the colonization resistance by the gut microbiota, studying diet-microbiota-pathogen axis holds promise in further understanding the pathogenesis mechanisms. Using a gnotobiotic mouse model containing a 14-member synthetic human gut microbiota (14SM), we have previously shown that dietary fiber deprivation promotes proliferation of mucin-degrading bacteria leading to a microbiota-mediated erosion of the colonic mucus barrier, which results in an increased susceptibility towards the rodent enteric pathogen Citrobacter rodentium. Here, we sought to understand how low-fiber diet affects susceptibility to Listeria monocytogenes and Salmonella typhimurium infections in our 14SM gnotobiotic mouse model, in BALB/c and C57BL/6N backgrounds, respectively. Intriguingly and in contrast to our results with C. rodentium, we observe that depriving mice of dietary fiber protected them from infections with the pathogens compared to mice fed a standard chow. The microbiota delayed the overall pathogenicity as compared to the onset of disease observed in germ-free control mice; nevertheless, we observe the same effect of diet in germ-free mice, suggesting that the susceptibility is microbiota independent. Our study points out an important observation that dietary fiber plays a crucial role on either the host susceptibility, the virulence of these pathogens, or both, which would be judicious to design and interpret future studies. ImportanceHuman enteric pathogens Listeria monocytogenes and Salmonella typhimurium are employed as classical models in rodent hosts to understand the pathogenesis mechanisms of food-borne pathogens. Research in the past decade has stressed importance of the composition of the gut microbiota in modulating susceptibility to these pathogens. Our results--using gnotobiotic mice and germ-free control animals--additionally suggest that the dietary fiber components dominate the impact of enteropathogenic virulence over the pathogenicity-modulating properties of the gut microbiota. The significance of our research is in the need to carefully choose a certain chow when performing the enteropathogen-associated mouse experiments and to cautiously match the rodent diets when trying to replicate experiments across different laboratories. Finally, our data underscore the importance of germ-free control animals to study these pathogens, as our findings would have been prone to misinterpretation in the absence of these controls.

microbiology↗

bioRxiv2020

FAM13A regulates maturation and effector functions of natural killer cells

The polymorphism of the gene FAM13A (family with sequence similarity 13, member A) is strongly linked to the risk of lung cancer and chronic obstructive pulmonary disease, which are among the leading causes of mortality and morbidity in lung-related diseases worldwide. However, the underlying molecular and cellular mechanisms through which FAM13A contributes to the pathogenesis of these diseases largely remain unclear. Here, using a Fam13a knock out (KO) mouse model, we showed that Fam13a depletion upregulated the expression of the terminal differentiation and inhibitory marker, KLRG1 (killer cell lectin-like receptor G1) in natural killer (NK) cells. NK cells from Fam13a-deficient mice showed impaired IFN-{gamma} production either against target tumor cells or following various cytokine cocktail stimulations. Furthermore, the number of lung metastases induced by B16F10 melanoma cells was increased in Fam13a-KO mice. Collectively, our data suggest a key role of FAM13A in regulating NK cell functions, indicating that the key lung-disease risk gene FAM13A might contribute to the pathogenesis of several lung diseases via regulating NK cells.

immunology↗