Biology subjects

Reinhardt, D.

Publications and source records attributed to Reinhardt, D..

16 recordsLinked to original sources

bioRxiv2026

A peptidomimetic inhibitor blocks Vibrio cholerae adhesin FrhA.

Cholera is a diarrheal disease from colonization of the small intestine by the Gram-negative bacterium Vibrio cholerae. Cholera remains a critical public health concern due to limitations in therapy and rising antibiotic resistance. The peptide-binding domain (PBD) of the adhesion protein FrhA is critical for V. cholerae intestinal colonization and biofilm formation. In a program targeted on blocking cholera infection, antagonists of the FrhA-PBD are described based on a tripeptide motif. Notably, constraint of the N-terminal tryptophan residue using 1,2,3,4-tetrahydro-{beta}-carboline-3-carboxylic acid (Tcc) and co-crystallization of H-(S)-Tcc-Thr-Asp-OH with an FrhA construct has provided structural information to guide inhibitor design. The diastereomer (R)-Tcc-Thr-Asp exhibited nanomolar binding affinity (Kd = 101 {+/-} 30.2 nM). H-(R)-Tcc-Thr-Asp-OH blocked bacterial hemagglutination mediated by FrhA-PBD and reduced biofilm formation in vitro. Moreover, it showed greater resistance to the digestive enzyme chymotrypsin than previously reported inhibitory pentapeptides, offering potential proteolytic stability while blocking FrhA-PBD-mediated adhesion in the intestine.

biochemistry↗

bioRxiv2026

Arbuscular mycorrhizal symbiosis increases drought resistance in the xerophytic argan tree ( Sideroxylon spinosum )

The xerophyte argan (Sideroxylon spinosum) has great ecological and socioeconomic importance for Morocco. However, it is endangered due to climate change and human overexploitation. We assess drought resistance traits of argan and test the potential of arbuscular mycorrhizal (AM) symbiosis to promote its growth and mitigate the consequences of drought. We compare ten endemic Moroccan mycorrhizal inocula with the model AM fungus Rhizophagus irregularis and with the drought-adapted isolate Diversispora omaniana. We integrated physiological phenotyping and RNA sequencing to investigate the stress resistance mechanisms of argan against drought. We show that AM symbiosis significantly mitigates drought effects on plant growth, mainly by improving water relations and photosynthetic efficiency, resulting in increased growth rates. Taken together, physiological and transcriptomic analyses show that stress markers were moderatly induced during severe drought stress irrespective of mycorrhizal status, suggesting that argan adopts a drought-coping strategy that involves both, stress avoidance and stress tolerance. Argan is highly AM-responsive, both at the phenotypic and transcriptomic level, suggesting that AM has great potential to promote argan growth under drought stress.

Plant Biology↗

bioRxiv2026

Rewiring of EGFR oncogenic program by opposing actions of membrane versus soluble CD109 in HNSCC

The epidermal growth factor receptor (EGFR) expression is often dysregulated in head and neck squamous cell carcinoma (HNSCC), driving cancer cell proliferation, invasion, and metastasis through diverse pathways, thereby contributing to aggressive chemo- and radio-therapy resistance. A GPI-anchored protein, CD109 is upregulated in multiple cancers, including HNSCC. While membrane-anchored CD109 (mCD109) is pro-tumorigenic in SCC via EGFR/STAT3 activation, the role of protease-cleaved soluble CD109 (sCD109) is poorly understood. Our groundbreaking findings demonstrate that sCD109 antagonizes EGFR signaling by directly binding to the EGFR extracellular domain, preventing mCD109-EGFR stabilizing interactions on the cell surface, followed by inhibition of EGFR phosphorylation at Y1068 and downstream signaling cascades (AKT, MAPK, and STAT3) consequently suppressing cancer cell migration, invasion, 3D tumor spheroid formation and angiogenic tube formation. In addition, we found that sCD109 regulates EGFR fates by inhibiting nuclear localization of phosphorylated EGFR and promoting EGFR degradation. Additionally, sCD109 significantly reduces EGF-induced expression of cancer stem cell markers (CD44 and CD133) and embryonic stem cell markers (Nanog and Sox2), suggesting a suppressive role in cancer stemness. Taken together, these results underscore the opposing roles of mCD109 and sCD109: with sCD109 acting as an antagonist by inhibiting mCD109/EGFR-driven oncogenic signaling and phenotypes. Our current findings reveal a complex interplay among mCD109, sCD109, and EGFR, identifying a mechanism for targeting EGFRs degradation in HNSCC, and lay the groundwork for future research on investigating sCD109s modulatory role in preclinical models of HNSCC.

Cancer Biology↗

bioRxiv2025

Pharmacological targeting of SOS1-RAS interaction triggers pancreatic β-cell proliferation and sustainably reverses diabetic hyperglycemia

Clinical studies have suggested that restoring a sufficient mass of functional {beta} cells can provide an effective treatment option for diabetes, however, it remains unclear whether this can be achieved through pharmacological stimulation of endogenous {beta}-cell proliferation. We demonstrate here that ectopic expression of a constitutively active form of Kras (KrasG12D) exclusively in pancreatic endocrine cells suppresses {beta}-cell proliferation, resulting in a dramatic reduction in {beta}-cell numbers and islet size. Conversely, we demonstrate that the potent and selective SOS1-RAS interaction inhibitor BI-3406 promotes unprecedented levels of {beta}-cell proliferation in primary human islets, both in culture and following transplantation in immunocompromised diabetic mice. Importantly, using murine models of streptozotocin-induced diabetes, we show that BI-3406 treatment restores {beta}-cell mass, leading to a gradual normalization of blood glucose and insulin levels, as well as to sustainable improvement in glucose tolerance. Our data provide the first pre-clinical evidence of an orally bioavailable KRAS inhibitor that can directly induce {beta}-cell regeneration.

cell biology↗

bioRxiv2025

Chromosome-level phased genome assembly of the Argan tree Sideroxylon spinosum L.

Argan (Sideroxylon spinosum L. previously known as Argania spinosa) is an endemic tree of Morocco, primarily used for seed oil extraction. Increasing interest in its biology and in genes relevant for oil quality and stress resistance demands for high-quality models of its genome and transcriptome. We integrated sequencing data from PacBio HiFi long-reads and Illumina Hi-C to generate independently assembled phased genome models for both parental haplotigs with lengths of 636Mb and 655 Mb, respectively, and with a BUSCO completeness score of >97.8%. Both haplotigs consist of 11 independently assembled fully resolved telomere-to-telomere chromosomes, similar to other species of the Sapotaceae (n = 10-13), and they both contain approximately [~]60% of highly repetitive regions. Comparative analysis with other Sapotaceous genomes suggests overall chromosome conservation, with repeat expansion and chromosome fusion for the two largest chromosomes (chr1, chr2). We also independently assembled the chloroplast genome. This high-quality genome assembly provides a valuable resource for advancing future research on argan biology, its genetic diversity, and traits relevant for fitness and oil production.

genomics↗

bioRxiv2024

A CELL BIOLOGY STUDY REVEALS NEW INSIGHTS INTO THE TRANSPORT MECHANISMS OF OOMYCETE EFFECTORS

Oomycete pathogens use dedicated effector proteins (also known as virulence factors) that manipulate the host during infection to the benefit of the pathogen. Despite extensive efforts, the understanding of how oomycete effector proteins are transported and delivered to the host is limited. Here, we show that Phytophthora capsici infecting Nicotiana benthamiana secretes its effectors through secretory pockets, haustoria, and from hyphae. We provide evidence that Avr3, belonging to the class of RxLR effector proteins that can be secreted and translocated to the plant cell, is found to accumulate in a distinct ring-shaped zone around the neck region of haustoria. The association with the haustorial neck is determined by an RxLR-EER motif and mutating this motif redirects Avr3 to the extrahaustorial matrix enveloping the full haustoria body. Furthermore, mass spectrometry analysis of immunoprecipitated Avr3 indicates that the RXLR motif remains intact when Avr3 is secreted from the haustorium during plant infection. We thus propose that the RXLR-EER motif determines the entry in the host cell by guiding Avr3 to the haustorial neck region, which may be a structure analogous to the Biotrophic Interfacial Complex of the fungus Magnaporthe sp.

cell biology↗

bioRxiv2024

Sanctioning of bacterial cheaters by the host plant in nitrogen-fixing symbiosis between Medicago truncatula and Sinorhizobium meliloti

In plant-microbe interactions, the host plant invests considerable amounts of resources in the microbial partner until the symbiotic machinery is established. If the microbial partner does not reciprocate with a comparable symbiotic benefit, the interaction represents a parasitic relationship. This is thought to elicit a plants response to prevent the selective disadvantage of being parasitized by such microbial cheaters. Indeed, negative feedback against bad mutualists, known as sanctioning, has been observed in interactions such as the arbuscular mycorrhizal and legume-rhizobium symbioses. Here, to study sanctioning by the plant host, we manipulate the exchange of resources between the model legume Medicago truncatula and its bacterial partner Sinorhizobium meliloti by three ways: mutating the bacterial nitrogenase enzyme, replacing nitrogen in the atmosphere with argon gas, and supplying high nitrate to the host. Then, we follow the consequences for the interaction by examining the metabolome, proteome, and phosphoproteome of nodules. We find that such cheating conditions result in sanctioning of the bacterial partner, and observe characteristic shifts including induced defense markers, repressed symbiotic markers, and changes in central metabolism that may be relevant for microbial fitness and that could therefore contribute to sanctioning.

plant biology↗

bioRxiv2024

Strigolactone receptor DAD2 promotes lateral root formation in Petunia hybrida

Strigolactone regulates various aspects of plant development and interactions with beneficial microbes. While the role of SL in shoot development is highly conserved between monocots and dicots, its role in root system architecture is controversial and context-dependent, although most of the SL appears to be produced there. A central parameter in plant fitness is root-to-shoot ratio, which is determined by growth and branching activity of both, the root as well as the shoot. We used previously characterized mutants defective in SL biosynthesis and sensing to test the role of SL in root growth and branching. Here, we show that a mutant defective in the petunia strigolactone receptor (dad2) exhibits defects in root meristem activity and root branching. Notably, this phenotype is not observed in the SL biosynthetic mutant dad1, suggesting that DAD2 may perceive a strigolactone analogue that is produced in a DAD1-independently fashion. DAD2 is induced in cortex cells adjacent to lateral root primordia, where it allows them to penetrate the cortex and to grow out of the main root. We propose a model by which inducible SL perception in cells adjacent to LRPs promotes auxin-induced cell wall remodeling in the cortex to allow passage of lateral roots. 1-sentence summaryLateral roots are initiated inside the main root, hence, they have to penetrate several cell layers to grow out. We propose that strigolactone cooperates with auxin to mediate lateral root emergence.

plant biology↗

bioRxiv2024

Conservation of symbiotic signalling across 450 million years of plant evolution

HighlightO_LIThe common symbiotic pathway is activated during arbuscular mycorrhizal symbiosis in Marchantia paleacea C_LIO_LIThe three core members of the common symbiotic pathway are essential for symbiosis in Marchantia paleacea C_LIO_LIThe molecular function of the CCaMK/CYCLOPS module is conserved across land plants C_LIO_LISymbiotic signalling has been conserved in plants for 450 million years C_LI The colonization of land by plants 450 million years ago revolutionized life on Earth1. The fossil record2 and genetic evidence in extant species3 suggest that this transition was facilitated by interactions with symbiotic arbuscular mycorrhizal (AM) fungi4. This ancestral symbiosis relied on the biosynthesis of chemicals by the host plant, both as signals5 and as nutrients3. In angiosperms, a signalling pathway involving the receptor-like kinase SYMRK/DMI26,7, the Calcium and Calmodulin-dependent protein kinase CCaMK/DMI38 and the transcription factor CYCLOPS/IPD39,10 has been described as the common symbiosis pathway (CSP), essential for the establishment of the AM symbiosis and the root-nodule symbiosis11. Phylogenetic and comparative phylogenomic analyses indicated an ancient origin of the CSP, present in all extant land plants forming intracellular symbioses12-15. Trans-complementation assays of the angiosperm mutants with orthologs from diverse species further indicated the conservation of the molecular function of the CSP across the embryophytes9,12,14-16. However, this correlative evidence did not allow testing the ancestral biological function of the CSP. In this study we demonstrate that SYMRK, CCaMK and CYCLOPS are essential for the colonization by AM fungi in bryophytes, indicating that plants have maintained a dedicated signalling pathway to support symbiotic interactions for 450 million years.

plant biology↗

bioRxiv2023

Altered enhancer-promoter interaction leads to MNX1 expression in pediatric acute myeloid leukemia with t(7;12)(q36;p13)

Acute myeloid leukemia (AML) with the t(7;12)(q36;p13) translocation occurs only in very young children and has a poor clinical outcome. The expected oncofusion between breakpoint partners (MNX1 and ETV6) has only been reported in a subset of cases. However, a universal feature is the strong transcript and protein expression of MNX1, a homeobox transcription factor that is normally not expressed in hematopoietic cells. Here, we map the translocation breakpoints on chromosomes 7 and 12 in affected patients to a region proximal to MNX1 and either introns 1 or 2 of ETV6. The frequency of MNX1 overexpression in pediatric AML (n=1556, own and published data) is 2.4% and occurs predominantly in t(7;12)(q36;p13) AML. Chromatin interaction assays in a t(7;12)(q36;p13) iPSC cell line model unravel an enhancer-hijacking event that explains MNX1 overexpression in hematopoietic cells. Our data suggest that enhancer-hijacking is a more common and overlooked mechanism for structural rearrangement-mediated gene activation in AML. Key pointsO_LIExpression analysis of over 1500 pediatric AML samples demonstrates MNX1 expression as a universal feature of t(7;12)(q36;p13) AML as well as in rare cases without t(7;12)(q36;p13) C_LIO_LIMNX1 is activated by an enhancer-hijacking event in t(7;12)(q36;p13) AML and not, as previously postulated, by the creation of a MNX1::ETV6 oncofusion gene. C_LI

cancer biology↗

bioRxiv2023

Pectin methylesterification modulates cell wall properties to promote neighbour proximity-induced hypocotyl growth

Plants growing with neighbours compete for light and consequently increase growth of their vegetative organs to enhance access to sunlight. This response, called shade avoidance syndrome (SAS), involves photoreceptors such as phytochromes as well as phytochrome interacting factors (PIFs), which regulate the expression of growth-mediating genes. Numerous cell wall-related genes belong to the putative targets of PIFs, and the importance of cell wall modifications for enabling growth was extensively shown in developmental models such as dark-grown hypocotyl. However, the role of the cell wall in the growth of de-etiolated seedlings regulated by shade cues remains poorly established. Through analyses of mechanical and biochemical properties of the cell wall coupled with transcriptomic analysis of cell wall-related genes, we show the importance of cell wall modifications in neighbour proximity-induced elongation. Further analysis using loss-of-function mutants impaired in the synthesis and remodeling of the main cell wall polymers corroborated this. We focused on the cgr2cgr3 double mutant that is defective in homogalacturonan (HG) methyltransferase activity required for methylesterification of HG-type pectins. By following hypocotyl growth kinetically and spatially and analyzing the mechanical and biochemical properties of cell walls, we found that methylesterification of HG-type pectins was required to enable global cell wall modifications. Moreover, HG-class pectin modification was needed for plant competition-induced hypocotyl growth. Collectively our work suggests that in the hypocotyl PIFs orchestrate changes in the expression of numerous cell wall genes to enable neighbour proximity-induced growth. One sentence summaryThe degree of methylesterification of pectins modulates global changes in the cell wall and its mechanical properties that contribute to the neighbour proximity-induced hypocotyl growth in Arabidopsis

plant biology↗

bioRxiv2023

Comprehensive single-cell genome analysis at nucleotide resolution using the PTA Analysis Toolbox

Detection of somatic mutations in single cells has been severely hampered by technical limitations of whole genome amplification. Novel technologies including primary template-directed amplification (PTA) significantly improved the accuracy of single-cell whole genome sequencing (WGS), but still generate hundreds of artefacts per amplification reaction. We developed a comprehensive bioinformatic workflow, called the PTA Analysis Toolkit (PTATO), to accurately detect single base substitutions, small insertions and deletions (indels) and structural variants in PTA-based WGS data. PTATO includes a machine learning approach to distinguish PTA-artefacts from true mutations with high sensitivity (up to 90% for base substitution and 95% for indels), outperforming existing bioinformatic approaches. Using PTATO, we demonstrate that many hematopoietic stem and progenitor cells of patients with Fanconi anemia, which cannot be analyzed using regular WGS technologies, have normal somatic single base substitution burdens, but increased numbers of deletions. Our results show that PTATO enables studying somatic mutagenesis in the genomes of single cells with unprecedented sensitivity and accuracy.

genomics↗

bioRxiv2022

RUNX1 isoform disequilibrium in the development of trisomy 21 associated myeloid leukemia

Aneuploidy is a hallmark of cancer, but its complex nature limits our understanding of how it drives oncogenesis. Gain of chromosome 21 (Hsa21) is among the most frequent aneuploidies in leukemia and is associated with markedly increased leukemia risk. Here, we propose that disequilibrium of the RUNX1 isoforms is key to the pathogenesis of trisomy 21 (i.e. Down syndrome)-associated myeloid leukemia (ML-DS). Hsa21-focused CRISPR-Cas9 screens uncovered a strong and specific RUNX1 dependency in ML-DS. Mechanistic studies revealed that excess of RUNX1A isoform - as seen in ML-DS patients - synergized with the pathognomonic Gata1s mutation in leukemogenesis by displacing RUNX1C from its endogenous binding sites and inducing oncogenic programs in complex with the MYC cofactor MAX. These effects were reversed by restoring the RUNX1A:RUNX1C equilibrium or pharmacological interference with MYC:MAX dimerization. Our study highlights the importance of alternative splicing in leukemogenesis, even on a background of aneuploidies, and opens new avenues for developing specific and targeted therapies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/483334v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@16c5a95org.highwire.dtl.DTLVardef@af0ec7org.highwire.dtl.DTLVardef@f36bcborg.highwire.dtl.DTLVardef@129e832_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

The megakaryocytic transcription factor ARID3A suppresses leukemia pathogenesis

Given the plasticity of hematopoietic stem/progenitor cells, multiple routes of differentiation must be blocked during acute myeloid leukemia pathogenesis - the molecular basis of which is incompletely understood. Here we report that post-transcriptional repression of transcription factor ARID3A by miR-125b is a key event in megakaryoblastic leukemia (AMKL) pathogenesis. AMKL is frequently associated with trisomy 21 and GATA1 mutations (GATA1s), and children with Down syndrome are at a high risk of developing this disease. We show that chromosome 21-encoded miR-125b synergizes with Gata1s to drive leukemogenesis in this context. Leveraging forward and reverse genetics, we uncover Arid3a as the main miR-125b target underlying this synergy. We demonstrate that during normal hematopoiesis this transcription factor promotes megakaryocytic differentiation in concert with GATA1 and mediates TGF{beta}-induced apoptosis and cell cycle arrest in complex with SMAD2/3. While Gata1s mutations perturb erythroid differentiation and induce hyperproliferation of megakaryocytic progenitors, intact ARID3A expression assures their megakaryocytic differentiation and growth restriction. Upon knockdown, these tumor suppressive functions are revoked, causing a dual megakaryocytic/erythroid differentiation blockade and subsequently AMKL. Inversely, restoring ARID3A expression relieves the megakaryocytic differentiation arrest in AMKL patient-derived xenografts. This work illustrates how mutations in lineage-determining transcription factors and perturbation of post-transcriptional gene regulation interplay to block multiple routes of hematopoietic differentiation and cause leukemia. Surmounting this differentiation blockade in megakaryoblastic leukemia by restoring the tumor suppressor ARID3A represents a promising strategy for treating this lethal pediatric disease. Key pointsO_LIRepression of megakaryocytic transcription factor ARID3A by miR-125b synergizes with GATA1s to induce leukemia C_LIO_LIRestoring ARID3A expression relieves megakaryocytic differentiation arrest in megakaryoblastic leukemia C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/440795v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@146c2a7org.highwire.dtl.DTLVardef@9599fdorg.highwire.dtl.DTLVardef@1b0d22borg.highwire.dtl.DTLVardef@1b61447_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2020

VAPYRIN attenuates defence by repressing PR gene induction and localized lignin accumulation during arbuscular mycorrhizal symbiosis of Petunia hybrids

O_LIThe intimate association of host and fungus in arbuscular mycorrhizal (AM) symbiosis can potentially trigger induction of host defence mechanisms against the fungus, implying that successful symbiosis requires suppression of defence. C_LIO_LIWe addressed this phenomenon by using AM-defective vapyrin (vpy) mutants in Petunia hybrida, including a new allele (vpy-3) with a transposon insertion close to the ATG start codon. We explore whether abortion of fungal infection in vpy mutants is associated with the induction of defence markers such as cell wall alterations, accumulation of reactive oxygen species (ROS), defence hormones, and induction of pathogenesis-related (PR) genes. C_LIO_LIWe show that vpy mutants exhibit a strong resistance against intracellular colonization, which is associated with the generation of thick cell wall appositions (papillae) with lignin impregnation at fungal entry sites, while no accumulation of defence hormones, ROS, or callose was observed. Systematic analysis of PR gene expression revealed that several PR genes are induced in mycorrhizal roots of the wild type, and even more in vpy plants. Some PR genes are induced exclusively in vpy mutants. C_LIO_LITaken together, these results suggest that VPY is involved in avoiding or suppressing the induction of a cellular defence syndrome that involves localized lignin deposition and PR gene induction. C_LI

plant biology↗

bioRxiv2017

An automated confocal micro-extensometer enables in vivo quantification of mechanical properties with cellular resolution.

How complex developmental-genetic networks are translated into organs with specific 3D shapes remains an open question. This question is particularly challenging because the elaboration of specific shapes is in essence a question of mechanics. In plants, this means how the genetic circuitry affects the cell wall. The mechanical properties of the wall and their spatial variation are the key factors controlling morphogenesis in plants. However, these properties are difficult to measure and investigating their relation to genetic regulation is particularly challenging. To measure spatial variation of mechanical properties, one must determine the deformation of a tissue in response to a known force with cellular resolution. Here we present an automated confocal micro-extensometer (ACME), which greatly expands the scope of existing methods for measuring mechanical properties. Unlike classical extensometers, ACME is mounted on a confocal microscope and utilizes confocal images to compute the deformation of the tissue directly from biological markers, thus providing cellular scale information and improved accuracy. ACME is suitable for measuring the mechanical responses in live tissue. As a proof of concept we demonstrate that the plant hormone gibberellic acid induces a spatial gradient in mechanical properties along the length of the Arabidopsis hypocotyl.\n\nTerms

plant biology↗