Biology subjects

Tucker, E.

Publications and source records attributed to Tucker, E..

10 recordsLinked to original sources

bioRxiv2026

CD47 blockade augments anti-GD2 driven phagocytosis in vitro but fails to improve in vivo efficacy in immune competent, chemoresistant neuroblastoma preclinical models

CD47 delivers a dominant "Dont Eat Me" signal that inhibits macrophage-mediated clearance of tumour cells. Using immune competent, chemoresistant neuroblastoma (NB) models, we tested a Fc-silent CD47 blocker (ALX301) with anti-GD2 antibody alone and in combination with a clinically aligned temozolomide/irinotecan chemoimmunotherapy backbone. Tumours expressed GD2 and CD47, and bound ALX301. In macrophage coculture assays, anti-GD2 antibody induced dose-dependent phagocytosis, whereas ALX301 or an anti-CD47 antibody alone did not. CD47 blockade in combination with a suboptimal concentration of anti-GD2 antibody showed an additive effect on phagocytosis in vitro. In vivo, however, ALX301 failed to improve tumour control or survival when added to anti-GD2 or to chemoimmunotherapy in two models. Toxicity was acceptable, showing only mild, expected red-cell changes without organ injury. This form of CD47 inhibition is therefore mechanistically active in vitro but insufficient to enhance anti-GD2 antibody-based therapy in immune competent mice bearing a chemoresistant NB, highlighting the potential need for myeloid-reprogramming partners.

immunology↗

bioRxiv2026

Aldoximes serve as auxin precursors and repress phenylpropanoid metabolism in tomato

Aldoximes are amino acid-derived metabolites that serve as precursors of auxins and modulate phenylpropanoid production in Arabidopsis. However, the enzymes responsible for aldoxime production in Solanaceae remain unknown. Here, we report the identification of aldoxime-producing enzymes in tomato (Solanum lycopersicum) and examine how altered aldoxime production affects auxin production and phenylpropanoid metabolism. Through homology-based analysis, we identified five putative CYP79 homologs in tomato, among which SlCYP79DB32 and SlCYP79DB52 exhibited aldoxime-producing activity toward multiple amino acids, including phenylalanine and tryptophan. SlCYP79DB32 and SlCYP79DB52 converted phenylalanine into phenylacetaldoxime (PAOx), whereas only SlCYP79DB52 converted tryptophan into indole-3-acetaldoxime (IAOx). Stable isotope-labeled feeding experiments revealed that IAOx and PAOx can be converted to the auxins indole-3-acetic acid (IAA) and phenylacetic acid (PAA), respectively. Consistently, tomato plants engineered to overproduce IAOx and PAOx accumulated elevated levels of IAA and PAA. These plants also accumulated lower levels of phenylpropanoids. In Brassicaceae plants such as Arabidopsis and Camelina, aldoxime accumulation represses phenylpropanoid production by promoting degradation of phenylalanine ammonia-lyase (PAL). However, aldoxime accumulation did not reduce PAL activity in tomato, suggesting an alternative mechanism in this species. Transcriptome analysis revealed extensive transcriptional reprogramming in aldoxime-overaccumulating tomato plants, including upregulation of stress- and defense-related genes. Despite the observed reduction in phenylpropanoid levels, transcript levels of most phenylpropanoid biosynthetic genes were not decreased, suggesting possible post-transcriptional regulation of this repression. Together, our findings demonstrate that aldoximes can serve as intermediates in auxin biosynthesis in tomato and reveal that aldoxime-mediated repression of phenylpropanoid metabolism extends beyond Brassicaceae.

plant biology↗

bioRxiv2025

Tuberculous meningitis alters the proteomic landscape of brain-derived extracellular vesicles

Tuberculous meningitis (TB meningitis), the deadliest form of Mycobacterium tuberculosis infection, leads to mortality and severe neurological disability despite standard therapy. Brain injury and microglial activation are major determinants of outcome, yet the mechanisms linking infection, inflammation and neuronal injury remain poorly understood. Extracellular vesicles (EVs), key mediators of cell-to-cell communication, have been investigated in pulmonary TB but their role in TB meningitis remains unexplored. We used our young rabbit model of TB meningitis to isolate pure, intact EVs from brain tissue (i.e., brain-derived EVs) from infected and uninfected rabbits and used nanoflow cytometry, transmission electron microscopy and protein quantification to characterize the EVs. Comparative proteomic profiling was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), followed by in silico pathway, cell-type and protein-protein interaction analyses using DAVID, Enrichr, and STRING databases. We found that EV isolation from fresh and frozen tissue was equivalent and demonstrated that M. tuberculosis infection activated EV biogenesis. Despite preserved vesicle morphology, EVs from infected brain showed a significant proteomic shift characterized by enrichment of TB host defense, microglial and immune activation, metabolic excitotoxicity, and neuronal injury. These proteome dysregulations suggest that infection reprograms brain EV cargo toward proinflammatory and metabolic stress responses while depleting neuronal and mitochondrial components. Collectively, these data demonstrate that M. tuberculosis infection alters the cargo and abundance of brain-derived EV, highlighting their potential as biomarkers and mediators of host-pathogen interactions in TB meningitis.

microbiology↗

bioRxiv2025

Phage-based microbiome manipulation elucidates interactions within community context

Testing microbial interaction hypotheses remains a major challenge in microbiome research. Bacteriophages have the potential to probe organism-organism interactions within complex microbiomes, yet are rarely used for this purpose. Here, we isolated nine narrow host range phages that replicate in several ecologically important Variovorax species. As Variovorax CL14 degrades the plant root-stunting hormone auxin, we used phages to eliminate V. CL14 from a rhizosphere consortium and reestablished the stunted root phenotype. We used three of the phages to deplete another Variovorax, SCN45, from complex communities to test correlation network-based hypotheses of thiamine interdependencies. Genome-resolved metagenomics revealed that specific taxa decreased in relative abundance following Variovorax depletion and could be rescued by thiamine supplementation. Thus, we confirmed thiamine production as the mechanistic basis for interdependence. These experiments lay the foundation for research that employs wildtype and engineered phages to test interaction hypotheses and for targeted microbiome manipulation.

microbiology↗

bioRxiv2025

Biosynthesis and Physiological Significance of Organ-Specific Flavonol Glycosides in Solanaceae

Flavonols are subclasses of flavonoids, with hundreds of structures identified in plants. This chemical diversity primarily arises from glycosylation, where sugars are selectively added to the flavonol backbone. While flavonol profiles vary across species and organs, the evolutionary forces shaping this chemodiversity and the physiological significance of specific glycosides remain a mystery. Here, we reveal that finely tuned transcriptional regulation and the sugar selectivity of glycosyltransferases drive the formation of distinct organ specific flavonol profiles and a specific flavonol is necessary for male fertility. In Solanaceae pollen, two flavonol glycosides, K2 (kaempferol 3-O-glucosyl(1 [->] 2)galactoside) and Q2 (quercetin 3-O-glucosyl(1 [->] 2)galactoside), are exclusively accumulated. K2 is evolutionarily conserved, while Q2 was lost over time. Consistently, K2 is essential for male fertility, whereas Q2 and aglycones fail to rescue fertility defects. These findings suggest that individual flavonol glycosides have distinct physiological roles, either actively maintained or discarded through evolutionary selection.

plant biology↗

bioRxiv2023

A century of sampling at an ecological preserve reveals declining diversity of wild bees

We analyzed the wild bee community from 1921 to 2018 at a nature preserve in southern Michigan, USA using museum records and found significant shifts in the bee community. Across the near century of records, species richness peaked in the 1970s and 1980s. There was an intensive bee survey completed by F.C. Evans in 1972 and 1973. We attempted to replicate his effort in 2017 and 2018, and again found a significant decline in species richness and evenness. There was also evidence of declining abundance in many of the more common species. We also conducted traits analyses using neural networks, revealing that oligolectic ground-nesting bees and cleptoparasitic bees were more likely to be extirpated whereas polylectic cavity-nesting bees were more likely to have persisted. Additionally, larger body size was associated with increased probability of local extirpation for polylectic cavity-nesting species. Larger phenological range was associated with increased chances of persistence for polylectic species, while it was associated with extirpation for oligolectic ground-nesting species. Species in the contemporary samples also had a more southerly overall distribution compared to the historic one. Open Research StatementData used for analyses in this manuscript, including Evans original dataset from 1972/1973 with updated species nomenclature, will be permanently archived at the USDA Ag Data Commons after the acceptance of this manuscript and will be citable and accessible here: https://data.nal.usda.gov/dataset/century-sampling-ecological-preserve-reveals-declining-diversity-wild-bees. Complete instructions on how to access all data referenced in this manuscript can be found in Appendix S1.

ecology↗

bioRxiv2022

COMBINATION THERAPIES TARGETING ALK-ABERRANT NEUROBLASTOMA IN PRECLINICAL MODELS.

BackgroundALK activating mutations are identified in approximately 10% of newly diagnosed neuroblastomas and ALK amplifications in a further 1-2% of cases. Lorlatinib, a third generation ALK inhibitor, will soon be given alongside induction chemotherapy for children with ALK-aberrant neuroblastoma. However, resistance to single agent treatment has been reported and therapies that improve the response duration are urgently required. We studied the preclinical combination of lorlatinib with chemotherapy, or with the MDM2 inhibitor, idasanutlin, as recent data has suggested that ALK inhibitor resistance can be overcome through activation of the p53-MDM2 pathway. AimsTo study the preclinical activity of ALK inhibitors alone and in combination with chemotherapy or idasanutlin. MethodsWe compared different ALK inhibitors in preclinical models prior to evaluating lorlatinib in combination with chemotherapy or idasanutlin. We developed a triple chemotherapy (CAV: cyclophosphamide, doxorubicin and vincristine) in vivo dosing schedule and applied this to both neuroblastoma genetically engineered mouse models (GEMM) and patient derived xenografts (PDX). ResultsLorlatinib in combination with chemotherapy was synergistic in immunocompetent neuroblastoma GEMM. Significant growth inhibition in response to lorlatinib was only observed in the ALK-amplified PDX model with the highest ALK expression. In this PDX lorlatinib combined with idasanutlin resulted in complete tumor regression and significantly delayed tumor regrowth. ConclusionOur study suggests that in neuroblastoma, high ALK expression could be associated with response to lorlatinib and either chemotherapy or idasanutlin. The synergy between MDM2 inhibition and ALK inhibition warrants further evaluation of this combination as a potential clinical approach for children with neuroblastoma. STATEMENT OF TRANSLATIONAL RELEVANCENeuroblastoma is a pediatric tumor of the developing sympathetic nervous system. Around 50% of high-risk neuroblastoma patients are curable. Mutations or amplification of Anaplastic Lymphoma Kinase (ALK) have emerged as a marker with which to further risk-stratify patients. The ALK inhibitor lorlatinib will soon be used alongside chemotherapy in upfront treatment of high-risk patients with ALK-aberrant disease. In this preclinical study, we used a panel of ALK aberrant neuroblastoma models to evaluate ALK inhibitors focusing on lorlatinib in combination with conventional chemotherapy and the small molecule MDM2 inhibitor idasanutlin. In both approaches we found synergy in models with high basal ALK expression without MAPK pathway alterations. We conclude that in neuroblastoma the level of ALK expression could be an additional biomarker predictive of clinical response to ALK inhibitors.

cancer biology↗

bioRxiv2021

CXCL8/CXCR2 signaling mediates bone marrow fibrosis and represents a therapeutic target in myelofibrosis

Pro-inflammatory signaling is a hallmark feature of human cancer, including in myeloproliferative neoplasms (MPNs), most notably myelofibrosis (MF). Dysregulated inflammatory signaling contributes to fibrotic progression in MF; however, the individual cytokine mediators elicited by malignant MPN cells to promote collagen-producing fibrosis and disease evolution remain yet to be fully elucidated. Previously we identified a critical role for combined constitutive JAK/STAT and aberrant NF-{kappa}B pro-inflammatory signaling in myelofibrosis development. Using single-cell transcriptional and cytokine-secretion studies of primary MF patient cells and two separate murine models of myelofibrosis, we extend this previous work and delineate the role of CXCL8/CXCR2 signaling in MF pathogenesis and bone marrow fibrosis progression. MF patient hematopoietic stem/progenitor cells are enriched in a CXCL8/CXCR2 gene signature and display dose-dependent proliferation and fitness in response to exogenous CXCL8 ligand in vitro. Genetic deletion of Cxcr2 in the hMPLW515L adoptive transfer model abrogates fibrosis and extends overall survival, and pharmacologic inhibition of the CXCR1/2 pathway improves hematologic parameters, attenuates bone marrow fibrosis, and synergizes with JAK inhibitor therapy. Our mechanistic insights provide a rationale for therapeutic targeting of the CXCL8/CXCR2 pathway in MF patients at risk for continued fibrotic progression.

cancer biology↗

bioRxiv2020

JNK signaling controls branching, nucleokinesis, and positioning of centrosomes and primary cilia in migrating cortical interneurons

Aberrant migration of inhibitory interneurons can alter the formation of cortical circuitry and lead to severe neurological disorders including epilepsy, autism, and schizophrenia. However, mechanisms involved in directing the migration of these cells remain incompletely understood. In the current study, we used live-cell confocal microscopy to explore the mechanisms by which the c-Jun NH2-terminal kinase (JNK) pathway coordinates leading process branching and nucleokinesis, two cell biological processes that are essential for the guided migration of cortical interneurons. Pharmacological inhibition of JNK signaling disrupts the kinetics of leading process branching, rate and amplitude of nucleokinesis, and leads to the rearward mislocalization of the centrosome and primary cilium to the trailing process. Genetic loss of Jnk from interneurons corroborates our pharmacological observations and suggests that important mechanics of interneuron migration depend on the intrinsic activity of JNK. These findings suggest that JNK signaling regulates leading process branching, nucleokinesis, and the trafficking of centrosomes and cilia during interneuron migration, and further implicates JNK signaling as an important mediator of cortical development. Summary StatementLoss of JNK signaling reduces growth cone branching frequency, limits interstitial side branch duration, alters rate and amplitude of nucleokinesis, and mislocalizes centrosomes and primary cilia in migrating cortical interneurons.

neuroscience↗

bioRxiv2018

GSK3 Controls Migration of the Neural Crest Lineage

Migration of the neural crest lineage is critical to its physiological function. Mechanisms controlling neural crest migration are comparatively unknown, due to difficulties accessing this cell population in vivo. Here, we uncover novel requirements of glycogen synthase kinase 3 (GSK3) in regulating the neural crest. We demonstrate that GSK3 is tyrosine phosphorylated (pY) in neural crest cells and that this activation depends on anaplastic lymphoma kinase (ALK), a protein associated with neuroblastoma. Consistent with this, neuroblastoma cells with pathologically increased ALK activity express high levels of pY-GSK3 and migration of these cells can be inhibited by GSK3 or ALK blockade. In normal neural crest cells, loss of GSK3 leads to increased pFAK and misregulation of Rac1 and lamellipodin, key regulators of cell migration. Genetic reduction of GSK-3 results in failure of migration. All together, this work identifies a role for GSK3 in cell migration during neural crest development and cancer.

developmental biology↗