Biology subjects

Johns, A.

Publications and source records attributed to Johns, A..

7 recordsLinked to original sources

bioRxiv2025

The Two Frontiers Project Field Handbook and OpenTools: Standardizing microbial fieldwork for biobank-scale sequencing and culturomics

From medicines to materials, our planets microbial diversity comprises an enormous wellspring of biotechnological potential. For centuries, microbiologists have developed tools for interrogating microbial function, ranging from microscopy and culturing to, more recently, metagenomics. However, deploying these tools during fieldwork requires substantial forward planning, interdisciplinary technical expertise, and plans for navigating permitting and the ethical implications of bioprospecting. To address these challenges, we built The Two Frontiers Project Handbook and OpenTools Resource, which aggregates our expertise in high-throughput sampling, sequencing, and culturing of microbes from thousands of samples. We provide our full suite of fieldwork methods as well as relevant software and hardware. We lay our standards for team roles and construction, general expedition planning, sample transport, permitting, and numerous other key aspects of executing a successful field campaign. The version-controlled resource is available at https://two-frontiers-project.github.io/ and is open for non-commercial use.

microbiology↗

bioRxiv2025

Mechanism of NanR transcriptional activation of sialic acid metabolism in Streptococcus pneumoniae.

In Streptococcus pneumoniae, the RpiR transcriptional regulator NanR (SpNanR) senses sialic acid in the environment and upregulates transcription of the nan and siaA operons to increase uptake and metabolism of sialic acid. The molecular basis of this activation is unknown. Here, we demonstrate that SpNanR binds N-acetylmannosamine-6-phosphate, a metabolite of sialic acid catabolism. SpNanR exists in a dimer-tetramer equilibrium, and N-acetylmannosamine-6-phosphate binding strongly stabilizes the tetramer. Crystal structures and site-specific substitutions demonstrate that N-acetylmannosamine-6-phosphate bridges and stabilizes the SpNanR tetramer. SpNanR binds its DNA recognition sequence with nanomolar affinity. Notably, the effector N-acetylmannosamine-6-phosphate does not affect the affinity of SpNanR for DNA. The DNA binding domains are not structurally coupled to the sugar isomerase domains, explaining why N-acetylmannosamine-6-phosphate binding does not affect DNA binding. Structural analysis reveals that sequence specificity arises through distortion of B-DNA and an unusual {pi}-stack formed by two arginine residues in the minor groove, while affinity is driven by backbone contacts. We propose a mechanism by which S. pneumoniae regulates sialic acid metabolism, consistent with our biophysical experiments and in vivo regulatory behavior. These findings define a unique activation mechanism for an RpiR regulator and provide new insights into carbohydrate-responsive gene regulation in pneumococci.

molecular biology↗

bioRxiv2025

Integrated in silico and in vitro approaches identify SNX.2112 as a drug vulnerability in t(7;12) AML stem-like cells

The t(7;12) translocation is a chromosomal rearrangement characteristic of infant Acute Myeloid Leukemia (AML). It arises in utero and results in ectopic overexpression of homeobox gene MNX1. Using a 3-dimensional (3D) model of blood development, we recently showed that t(7;12)-AML originates at the endothelial-to-hematopoietic transition, explaining its characteristic gene expression signature. Herein, we employ that signature to interrogate the transcriptional profiles of hundreds of human cell lines against the GDSC database of drug sensitivities to identify candidate drugs against t(7;12)-AML. We employ a cell line in which we engineered t(7;12) and systematically test the candidate drugs by cell surface phenotype and clonogenic assays. Importantly, we identify HSP90 inhibitor SNX.2112 as a potential therapeutic agent against t(7;12)-AML. SNX.2112 selectively eliminates colony-initiating leukemia progenitors in vitro and decreases MNX1 expression, effects recapitulated by other HSP90 inhibitors. SNX.2112 acts at least partly through destabilisation of STAT5 signalling. Critically, SNX.2112-differential signatures uniquely map to progenitors with hemato-endothelial characteristics in t(7;12)-AML patient blasts, suggesting targeting of leukemia-initiating cells. Combinatorial treatment with chemotherapeutic agents indicates synergy, suggesting SNX.2112 potential as a targeted and cytotoxicity-sparing therapeutic approach. Overall, we successfully use an integrated computational and multi-model experimental approach to identify a drug vulnerability of t(7;12)-AML. Key pointsO_LIClassifier-based in silico drug screening identifies vulnerabilities of t(7;12)-infant leukemia C_LIO_LI2D and 3D models of t(7;12)-leukemia match HSP90 inhibition cellular and molecular responses to candidate leukemia stem cells in t(7;12) patient analysis. C_LI

cancer biology↗

bioRxiv2025

Tissue Factor Expression in Penile Squamous Cell Carcinoma: A Marker of HPV-Independent Disease

In a series of 33-patients, we evaluated tissue factor (TF) expression in penile squamous cell carcinoma (PSCC). A tissue microarray (TMA) was constructed with 3 cores per patient tumor (99 total cores). Anti-TF antibody staining was performed by immunohistochemistry and H-scores for membrane and cytoplasm staining were assessed (range 0-300). Percentage of cores and patient tumors staining positive for TF ([≥]10% of tumor cells with at least 1+ intensity in cytoplasm and/or membrane) and H-scores were described and compared with HPV and p16 status. Association of TF expression with tumor grade, presence of metastatic disease, lymphovascular invasion (LVI), perineural invasion (PNI), aberrant p53 expression, recurrence free survival (RFS), and cancer specific survival (CSS) were assessed. Nectin-4 and TROP2 staining and their association with clinical/pathological data was determined in a similar manner. TF staining was more prominent in HPV-negative tumors in both the membrane (H-score 69.6 vs 18.8; p=0.003) and cytoplasm (H-score 59.2 vs. 17.7, p=0.007). Cytoplasmic (H-score 61.7 vs 11.7, p=<0.001) and membrane TF staining (H-score 71.7 vs 15.0, p=<0.001) favored p16 negative tumors. The p53 status was more likely to be aberrant in the higher TF staining samples (cytoplasm H-score 61.7 vs 18.3, p=0.012; membrane H-score 67.5 vs 20.3, p=0.006). We observed an association with TROP2 staining and positive p16 status (membrane H-score 120.3 vs. 85, p=0.052; cytoplasmic H-score 135 vs. 107.5, p=0.041). We observed an association of TROP2 staining with positive LVI (membrane H-score 136.7 vs. 66.7, p=0.014; cytoplasmic H-score 110 vs. 93.3, p=0.04). We found no association between TF, TROP2, or nectin-4 staining with CSS or RFS; however, we suspect that this is due to our small sample size. Our results indicate that TF expression could be positive biomarker for HPV-independent, p53-aberrant PSCC, while TROP2 could be associated with HPV-associated PSCC.

pathology↗

bioRxiv2022

βIII-Tubulin is a Brake on Extrinsic Cell-Death in Pancreatic Cancer

The microtubule protein, {beta}III-tubulin, has been implicated as a prognostic, pro-survival, and chemoresistance factor in some of the most lethal malignancies including pancreatic ductal adenocarcinoma (PDAC). However, precise survival mechanisms controlled by {beta}III-tubulin in cancer cells are unknown. Here, we report an unexpected role of {beta}III-tubulin as a brake on extrinsic caspase 8-dependent apoptosis in PDAC. We show that {beta}III-tubulin knockdown frees death-receptor DR5 to increase its membrane diffusion, clustering, and activation of cell-death. We demonstrate that {beta}III-ubulin silencing increases sensitivity of PDAC cells to chemotherapeutic and microenvironment-derived extrinsic cell-death signals including TRAIL, TNF, and FasL. Finally, nanoparticle delivery of {beta}III-tubulin siRNA to mouse orthotopic PDAC tumours in vivo and human patient-derived PDAC tumour explants ex vivo increases extrinsic apoptosis and reduces tumour progression. Thus, silencing of {beta}III-tubulin represents an innovative strategy to unleash a suicide signal in PDAC cells and render them sensitive to microenvironment and chemotherapy-derived death signals.

cancer biology↗

bioRxiv2022

Artificial Hsp100-mediated systems for re-localizing protein aggregates

Spatial Protein Quality Control (sPQC) sequesters misfolded proteins into specific, organelle-associated inclusions within the cell to harness their toxicity. To approach the role of sPQC in cellular fitness, neurodegenerative diseases and aging, we report on the construction of Hsp100-based systems in yeast cells, which can artificially target protein aggregates to non-canonical locations. We demonstrated that aggregates of mutant Huntingtin (mHtt), the disease-causing agent of Huntingtons disease can be artificially targeted to daughter cells as well as to eisosomes and endosomes with this approach. Removing aggregates from mother cells did not significantly affect their lifespan and targeting mHtt to multiple smaller aggregates rather than one large inclusion did not alter its toxicity. We demonstrated that this approach is able to manipulate mHtt inclusion formation also in human cells and has the potential to be a useful complementation to present therapeutic approaches aimed at alleviating age-related neurodegenerative diseases.

cell biology↗

bioRxiv2019

Targeting DNA damage response and Replication Stress in Pancreatic Cancer

Continuing recalcitrance to therapy cements pancreatic cancer (PC) as the most lethal malignancy, which is set to become the second leading cause of cancer death in our society. We interrogated the transcriptome, genome, proteome and functional characteristics of 61 novel PC patient-derived cell lines to define novel therapeutic strategies targeting the DNA damage response (DDR) and replication stress. We show that patient-derived cell lines faithfully recapitulate the epithelial component of pancreatic tumors including previously described molecular subtypes. Biomarkers of DDR deficiency, including a novel signature of homologous recombination deficiency, co-segregates with response to platinum and PARP inhibitor therapy in vitro and in vivo. We generated a novel signature of replication stress with potential clinical utility in predicting response to ATR and WEE1 inhibitor treatment. Replication stress and DDR deficiency are independent of each other, creating opportunities for therapy in DDR proficient PC, and post-platinum therapy.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC=\"FIGDIR/small/713545v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (47K):\norg.highwire.dtl.DTLVardef@106f2b8org.highwire.dtl.DTLVardef@1294d22org.highwire.dtl.DTLVardef@86f5d3org.highwire.dtl.DTLVardef@751e13_HPS_FORMAT_FIGEXP M_FIG C_FIG STATEMENT OF SIGNIFICANCEWe define therapeutic strategies that target subgroups of PC using novel signatures of DNA damage response deficiency and replication stress. This potentially offers patients with DNA repair defects therapeutic options outside standard of care platinum chemotherapy and is being tested in clinical trials on the Precision-Panc platform.

cancer biology↗