Biology subjects

Davies, C.

Publications and source records attributed to Davies, C..

At least 19 recordsLinked to original sources

bioRxiv2026

Energetic coupling of an active site residue in penicillin-binding protein 2 from Neisseria gonorrhoeae with a resistance-associated conformational switch in the β3-β4 loop

Mosaic penA alleles encoding highly mutated variants of penicillin-binding protein 2 (PBP2) are the principal determinants of ceftriaxone resistance in Neisseria gonorrhoeae. Resistance-associated mutations in PBP2 from the ceftriaxone-resistant strain H041 restrict formation of the inward conformation of the {beta}3-{beta}4 loop associated with efficient acylation, but how {beta}-lactam recognition is coupled to this conformational switch is unknown. Because the conserved active-site residue Tyr422 interacts with the R1 substituent of {beta}-lactams, we investigated its role in coupling ligand recognition and acylation activity. Mutation of Tyr422 to Ala lowered acylation rates by up to 120-fold for cefoperazone and piperacillin, whereas acylation rates of ceftriaxone increased 4-fold. Unexpectedly, the crystal structure of the Y422A mutant acylated by ceftriaxone revealed that the {beta}3-{beta}4 loop had adopted the inward, high-activity conformation, despite position 422 being spatially distant from the loop. Transformation experiments showed that cell viability requires a tyrosine at position 422, indicating the residue is essential for transpeptidase function. Together, these findings reveal an energetic coupling between an active-site residue in PBP2 and a conformational switch whose equilibrium is altered by resistance mutations. The previously observed higher activity of {beta}-lactams containing extended R1 groups is consistent with stronger interactions with Tyr422 that favor the conformational switch. Molecular modeling suggests that such groups enhance activity by mimicking the iso-Glu region of the pentapeptide substrate. Overall, we propose that access to the high-activity state of PBP2 where the {beta}3-{beta}4 loop is inward is regulated by interactions between Tyr422 and {beta}-lactam R1 groups, and that resistance mutations function by tilting the balance toward a lower activity state.

biochemistry↗

bioRxiv2026

ASS1 deficiency defines a therapeutic vulnerability in Philadelphia chromosome-positive acute lymphoblastic leukaemia

Amino acid deprivation with L-asparaginase is a cornerstone of treatment in acute lymphoblastic leukaemia (ALL), but clinical challenges limit its use in adults. Deficiency in the enzyme argininosuccinate synthase (ASS1-low) confers arginine auxotrophy, defining a dependence on extracellular arginine, and represents an analogue metabolic vulnerability that is targetable through arginine deprivation. We analysed transcriptomic data across >550 adult B-ALL cases to establish clinico-biologic characteristics of low ASS1 expression identifying the Philadelphia chromosome-positive (Ph+) ALL subgroup as a stereotypical arginine auxotroph within molecularly diverse B-ALL. Functionally, arginine deprivation with pegargiminase induced robust apoptosis in both Ph+ ALL cell lines and primary samples in an ASS1-dependant manner and was highly effective as a monotherapy treatment in independent Ph+ ALL patient derived xenografts. Mechanistically, arginine deprivation induces endoplasmic reticulum stress mediated apoptosis which was orthogonal to tyrosine kinase inhibition (TKI) mediated outcomes. Using in vitro and in vivo models of non-genetically mediated TKI-resistance, we demonstrate pegargiminase and TKI combinations robustly eradicates TKI-resistant leukaemia. Thus, we establish ASS1 deficiency (ASS1-low) as a therapeutically actionable vulnerability in Ph+ ALL and a strategy to bypass TKI-resistance, supporting clinical evaluation of arginine deprivation as a novel adjunct to chemotherapy-free treatment.

cancer biology↗

bioRxiv2026

Characterisation of novel Campylobacter jejuni Type VI secretion system (T6SS) effectors and exploration of the roles of the C. jejuni T6SS in bacterial antagonism and human host cell interaction

Campylobacter jejuni is a leading global cause of acute foodborne gastroenteritis however, C. jejuni lacks some of the classic virulence determinants associated with other common enteric bacterial pathogens. In recent years an increasing number of C. jejuni isolates have been identified to encode Type Six Secretion System (T6SS), an apparatus utilised by Gram-negative bacteria to secrete toxic bacterial effectors into neighbouring cells. Despite the prevalence of the T6SS and previous investigations, the roles of the C. jejuni T6SS are still not well characterised especially when compared to our knowledge of other clinically relevant T6SS-positive bacterial species. Additionally, as of yet, no C. jejuni T6SS cargo effectors have been characterised. In this study, we show the C. jejuni 488 strain T6SS displays contact-dependent antagonistic behaviour towards T6SS-negative C. jejuni, Campylobacter coli, Escherichia coli and Enterococcus faecium strains suggesting the presence of the T6SS contributes to the competitive capacity of this C. jejuni T6SS-positive strain. Moreover, this antagonistic activity is linked to the functionality of CJ488_0980 and CJ488_0982, two novel putative Tox-REase-7 domain-containing effectors, which were identified through bioinformatical analysis of the C. jejuni 488 strain genome. Additionally, our investigations propose the C. jejuni 488 T6SS contributes to interaction, invasion and intracellular survival in human intestinal epithelial cells (IEC). Collectively, these initial findings are the first examples of in vitro investigation of putative cargo effectors in Campylobacter spp. and provide valuable insights into the roles of C. jejuni T6SS effectors in bacterial competition and pathogenesis. This study highlights the importance of T6SS as an emerging virulence determinant in Campylobacter spp. warranting further investigation.

microbiology↗

bioRxiv2026

LRSomatic: a highly scalable and robust pipeline for somatic variant calling in long-read sequencing data

MotivationLong-read sequencing is increasingly used in cancer research and clinical genomics due to its ability to resolve complex genomic variation and previously inaccessible regions of the genome. However, dedidated workflows for comprehensive somatic variant analysis from long-read whole-genome data remain scarce, limiting uptake in cancer genomics. ResultsWe present LRSomatic, a Nextflow-based, nf-core-compliant pipeline supporting somatic SNV, indel, structural variant, and copy number calling from PacBio HiFi and ONT data. LRSomatic supports paired tumor-normal and tumor-only designs, as well as integration of epigenetic integration via Fiber-seq. Benchmarked on COLO829 and HG008 reference cell lines, LRSomatic achieves state-of-the-art performance across both platforms and variant types. Applied to a case of clear cell sarcoma, it recovers all identified driver alterations, including the pathognomonic EWSR1::ATF1 fusion, and resolves haplotype-specific chromatin accessibility via Fiber-seq. Availability and ImplementationFreely available at https://github.com/intgenomicslab/lrsomatic, implemented in Nextflow DSL2, supported via Docker and Singularity.

bioinformatics↗

bioRxiv2026

Menaquinone depletion resensitises bedaquiline-resistant tuberculosis

Tuberculosis remains a leading cause of global mortality, and rising bedaquiline resistance threatens the effectiveness of current drug-resistant treatment regimens. Bedaquiline resistance typically arises through mutations in Rv0678 that upregulate drug efflux and confer cross-resistance to multiple drug classes. Here, we identify and optimise a chemical series targeting MenG, a central enzyme in the menaquinone biosynthesis pathway, yielding potent bactericidal inhibitors with in vivo efficacy. Strikingly, MenG inhibition restored bedaquiline susceptibility in efflux-mediated resistant strains, an effect confirmed in vivo where combination therapy achieved a 99.8% reduction in bacterial burden compared with bedaquiline alone. Potentiation also extended to pretomanid and other key agents. Disruption of upstream menaquinone and shikimate pathway enzymes produced similar resensitisation, establishing these pathways as tractable targets for restoring drug susceptibility in Mycobacterium tuberculosis. These findings provide a novel strategy to overcome bedaquiline resistance and strengthen future regimens for efflux-mediated drug-resistant tuberculosis.

microbiology↗

bioRxiv2025

Antibiotic-resistance mutations in penicillin-binding protein 2 from the ceftriaxone-resistant Neisseria gonorrhoeae strain H041 strike a delicate balance between increasing resistance and maintaining transpeptidase activity

The mosaic penA allele (penA41) from H041, the most ceftriaxone-resistant Neisseria gonorrhoeae strain identified to date, encodes a variant of the essential Penicillin-Binding Protein 2 (PBP2) with 60 amino acid mutations compared to PBP2 from the antimicrobial-susceptible strain, FA19. Based on previous work from our lab and others, we identified a minimal set of 10 mutations that, when introduced into the {beta}-lactam antibiotic-susceptible penA allele from FA19 (penA19), confers two-thirds of the ceftriaxone and cefixime resistance compared to the penA41 allele. Three mutations (A311V, I312M, and V316P) are in the 2 helix of PBP2 containing the catalytic serine (Ser310), two (F504L and N512Y) are in the 3-4 loop that is important in binding and acylation, and one (G545S) interacts with conserved amino acids in the active site. The seventh mutation, T483S, confers substantial resistance to ceftriaxone within the minimal mutant set but requires the presence of three epistatic mutations located on the other side of the protein that do not alter resistance on their own yet are necessary to retain essential transpeptidase activity. These epistatic mutations change the backbone dihedral angles at position-447, which may increase flexibility of the enzyme and help restore essential transpeptidation. Our results highlight the complex balance necessary for evolving cephalosporin resistance while also retaining sufficient transpeptidase function in PBP2. Author SummaryIn this study, we set out to understand how Neisseria gonorrhoeae, the bacterium that causes gonorrhea, is able to resist the last remaining recommended antibiotic, ceftriaxone. Gonorrhea is a common sexually transmitted infection worldwide, and rising resistance threatens to make it untreatable. We focused on penicillin-binding protein 2 (PBP2), which is essential for the bacteriums survival and is the lethal target of ceftriaxone. By incorporating a subset of the 60 PBP2 mutations found in a highly resistant strain into PBP2 from an antibiotic-susceptible strain, we discovered that resistance evolved from a combination of mutations that work together to directly reduce the capacity of ceftriaxone to inactivate the protein and others that act as "supporting" mutations to keep the protein functional despite the presence of the resistance mutations. Our study highlights how N. gonorrhoeae successfully negotiates the delicate balance between resistance and function to escape the lethal action of antibiotics.

microbiology↗

bioRxiv2025

Placental transcriptome profiling in congenital Chagas disease: gene networks associated with transmission

Chagas disease, caused by Trypanosoma cruzi, affects over seven million people globally. Vertical transmission during pregnancy significantly contributes to the urban spread of the disease, even in non-endemic areas. The placental barrier plays a key role in preventing fetal infection, although the molecular mechanisms underlying congenital transmission remain unclear. To identify placental factors associated with transmission, we conducted a transcriptomic study comparing placental tissues from deliveries of congenitally infected (M+B+), exposed but uninfected (M+B-), and unexposed/uninfected (M-B-) newborns. Differential gene expression analysis of transmitting placentas revealed that ENSG00000304767, a novel lncRNA sense intronic to CEMIP was overexpressed as well as CGB5, while CEMIP, CADM3, CADH11 and PRXX1 were underexpressed. In non-transmitting placentas, the long non-coding RNA MIR4300 was overexpressed while CGB5 was underexpressed. These results suggest that cell adhesion and the extracellular matrix integrity are altered in transmitting placentas. Additionally, gene set enrichment analysis using the GO library revealed immune-related terms underrepresented in both infected mother groups, and confirmed that extracellular matrix processes, particularly collagen organization and metabolism, constitute important factors in transmission events. Analysis using the Cell Type library showed that extravillous trophoblasts were overrepresented in M+B+, but the opposite in M+B-. In contrast, syncytiotrophoblasts and villous cytotrophoblasts were overrepresented in non-transmitting vs. control cases. Immune-related placental cell types were consistently reduced in both M+ groups when compared to controls. The co-expression network analysis confirmed that the placental signaling and structural integrity were compromised in transmitting cases. ENPP1 and SLC16A10 emerged as hub genes with pivotal roles in the pathways altered during congenital infection. These findings highlight key placental transcriptional alterations linked to congenital T. cruzi transmission and provide insight into potential molecular mechanisms of fetal protection or susceptibility. Author summaryChagas disease, caused by the parasite Trypanosoma cruzi, can be passed from mother to baby during pregnancy, constituting the main transmission way in urban and non-endemic areas. The placenta normally acts as a barrier to protect the fetus, but how this barrier fails in congenitally transmitted cases is still not well understood. Thus, we analyzed the gene expression in placental tissues from three groups: infected mothers that transmitted the parasite, infected mothers that did not transmit it, and uninfected mothers. We found that certain genes involved in immune response, hormone regulation, and the structure of the placenta showed clear differences among these groups. In particular, CGB5, involved in the production of pregnancy hormones, showed opposite activity patterns depending on whether the mother transmitted the parasite or not. We also found that specific placental cell types that help anchor the placenta or form its protective outer layer changed their expression pattern in transmitting cases. These shifts suggest that both the physical structure and immune system of the placenta may be altered in a way that allows the parasite to reach the fetus. Our findings reveal important molecular clues that could help predict congenital transmission of Chagas disease.

molecular biology↗

bioRxiv2025

MYBL2 maintains stemness and promotes theta-mediated end joining in triple negative breast cancer

Triple negative breast cancer (TNBC) has a poor prognosis due to limited treatment options and high metastasis risk. Breast cancer (BC) stem/progenitor cells, also known as tumour initiating cells, are a small, difficult to target population within the tumour responsible for metastasis and therapy resistance. MYBL2 overexpression is commonly linked to poor prognosis and metastasis but its role in BC stem/progenitor cells remains elusive. To determine the role of MYBL2 in BC stem/progenitor cells we generated TNBC cell lines with inducible MYBL2 downregulation. Our findings reveal that elevated MYBL2 is essential for self-renewal, DNA repair, and replication stress response in these cells and lowering MYBL2 impairs stemness and self-renewal both in vitro and in vivo. Accordingly, our functional and mechanistic analyses indicate that high-MYBL2 stem/progenitor cells exhibit increased sensitivity to Pol{theta} inhibitors which is lost upon MYBL2 downregulation due to transcriptional suppression. Combining Pol{theta} inhibitors with ATR inhibitors further enhances this sensitivity, in vitro and ex vivo. This study thus identifies Pol{theta}/ATR inhibition as a synthetic lethality strategy to eradicate BC stem/progenitor cells and underscores MYBL2 expression as a biomarker for patient stratification in this treatment.

cancer biology↗

bioRxiv2025

Unfolded protein response is a critical mediator in Campylobacter jejuni pathogenesis and host defence

Campylobacter jejuni is the major bacterial cause of foodborne gastroenteritis worldwide. How this pathogen interacts with the host defence machinery of human intestinal epithelial cells (IECs) and is involved in pathogenesis remains elusive. Bacterial pathogens utilise strategies to gain access to the eukaryotic cell machinery that can involve subversion of biological processes in host. Unfolded protein response (UPR) is a highly conserved host cell stress response to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and is a conserved evolutionary response against invading pathogens. Several bacterial pathogens can induce the UPR for their own survival and thus design a dual scenario where UPR can both protect and facilitate pathogen evasion. Herein, we investigated whether UPR represents a virulence mechanism exploited by C. jejuni during bacterial invasion in human IECs. Our data show that following C. jejuni infection, we observe upregulation of protein kinase R-like ER kinase (PERK), inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6) pathways of the UPR, albeit differentially in human T84 and Caco-2 cells. Chemical induction of UPR by thapsigargin in host cells reduced intracellular survival of C. jejuni while conversely pretreatment with UPR inhibitors increased intracellular survival of C. jejuni and attenuated IL-8 release. Finally, we show that C. jejuni mutant C. jejuni capsular polysaccharide and flagella contribute to UPR activation in IECs. Collectively, these findings provide mechanistic insights into how C. jejuni infection leads to UPR activation and inflammation, potentially contributing to downstream C. jejuni-mediated damage. Author SummaryCampylobacter jejuni is one of the most prevalent bacterial causes of foodborne human gastroenteritis worldwide. The common symptoms of campylobacteriosis include diarrhoea, abdominal pain and fever. C. jejuni-induced diarrhoea is associated with disruption of tight junctions and adherens junctions, downregulation of epithelial sodium channels and disruption of bile reabsorption. In addition, C. jejuni-induced diarrhoea in part result from intestinal inflammation caused by increased C. jejuni colonisation and invasion due to dysfunctional intestinal barrier. C. jejuni was reported to cause an inflammatory signalling cascade via ligand recognition by Toll-like receptor 2 (TLR2), TLR4 and nucleotide-binding oligomerisation domain (NOD) in IECs. However, other potential mechanisms of C. jejuni-induced inflammation, with respect to the IEC responses remains unknown. In this study, we demonstrate UPR activation following C. jejuni infection. The UPR is a conserved eukaryotic regulatory response which is initiated to relieve ER stress and recover ER homeostasis, however several bacteria have evolved to exploit UPR pathways for their own survival and replication, creating a dual scenario where UPR can both protect and facilitate pathogen evasion. This study shows that the activation of the PERK pathway of host UPR is activated in the presence of live C. jejuni or its structural components, flagella and a capsular polysaccharide. Furthermore, we propose that although activation of the UPR is a conserved evolutionary response against invading pathogens, UPR induction induces inflammation which potentially contributes to C. jejuni-mediated damage.

microbiology↗

bioRxiv2024

A new class of penicillin-binding protein inhibitors to address drug-resistant Neisseria gonorrhoeae

{beta}-Lactams are the most widely used antibiotics for the treatment of bacterial infections because of their proven track record of safety and efficacy. However, susceptibility to {beta}-lactam antibiotics is continually eroded by resistance mechanisms. Emerging multidrug-resistant (MDR) Neisseria gonorrhoeae strains possessing altered penA alleles (encoding PBP2) pose a global health emergency as they threaten the utility of ceftriaxone, the last remaining outpatient antibiotic. Here we disclose a novel benzoxaborinine-based penicillin-binding protein inhibitor series (boro-PBPi) that is envisioned to address penA-mediated resistance while offering protection against evolution and expansion of {beta}-lactamases. Optimization of boro-PBPi led to the identification of compound 21 (VNRX-14079) that exhibits potent antibacterial activity against MDR N. gonorrhoeae achieved by high affinity binding to the PBP2 target. Boro-PBPi/PBP2 complex structures confirmed covalent interaction of the boron atom with Ser310 and the importance of the {beta}3-{beta}4 loop for improved affinity. 21 elicits bactericidal activity, a low frequency of resistance, a good safety profile, suitable pharmacokinetic properties, and in vivo efficacy in a murine infection model against ceftriaxone-resistant N. gonorrhoeae. 21 is a promising anti-gonorrhea agent poised for further advancement.

microbiology↗

bioRxiv2024

FAK modulates glioblastoma stem cell energetics via actomyosin contractility: regulation of glycolysis and mitochondrial function

Glycolysis and the TCA cycle are reprogrammed in cancer cells to meet bioenergetic and biosynthetic demands, including by engagement with the extracellular matrix (ECM). We show that focal adhesion kinase (FAK), a mediator of integrin-ECM signalling, is driving cellular energetics in a stem cell model of glioblastoma (GBM). FAK gene deletion inhibits both glycolysis and glutamine oxidation, with increased mitochondrial fragmentation and elevated phosphorylation of the mitochondrial protein MTFR1L at S235. Simultaneously, FAK loss causes a mesenchymal to epithelial transition, enhanced acto-myosin contractility as shown by phospho-myosin light chain (p-MLC S19) and impaired cell migration/invasiveness. Rho-kinase (ROCK) inhibitors suppress p-MLC (S19) and restore glutamine oxidation and elongation of mitochondria. Thus, FAK is a key regulator of both glycolysis and glutamine oxidation mediated by acto-myosin contractility that controls both cell and mitochondrial morphology. Moreover, FAK-dependent cellular energetics are coincident properties with GBM stem cell migration, invasiveness and tumour growth in vivo.

cancer biology↗

bioRxiv2024

The thermotolerant Arabian killifish, Aphanius dispar, as a novel infection model for human fungal pathogens

Candida albicans: a fungal pathogen, can cause superficial and fatal infections in humans. An important virulence factor in C. albicans dissemination is the transformation from yeast to an invasive hyphal form, which is favoured at human body temperature. Zebrafish, a useful model for studying C. albicans infections, cannot survive at 37{degrees}C. Arabian killifish, Aphanius dispar, an emerging teleost model can tolerate temperatures up to 40 {degrees}C for up to 12 days (independent feeding time) allowing for longer analysis compared to zebrafish. This study introduces A. dispar as a thermo-relevant and a more accurate reporter of the virulence mechanisms relevant to C. albicans as a human pathogen. Using A. dispar, we tested virulence at human skin (30 {degrees}C), body temperature (37 {degrees}C) and a high fever condition (40{degrees}C). Infection by C. albicans at 37{degrees}C and 40{degrees}C significantly increased virulence, reduced survival of AKF embryos and formed invasive hyphal network compared to 30 {degrees}C. Two mutant strains of C. albicans. pmr1{Delta} (with aberrant cell surface glycans) exhibited reduced virulence at 37{degrees}C, whereas rsr1{Delta} (lacking a cell polarity marker) showed less virulence at 30 {degrees}C. Additionally, anti-fungal treatment rescued AKF survival in a dose-dependent manner, indicating AKFs potential for in vivo drug testing. Our data indicates the quantitative and qualitative importance of examining virulence traits at physiologically relevant temperatures and demonstrates an equivalence to findings for systemic infection derived in mouse models. The A. dispar embryo therefore provides an excellent in vivo model system for assessing virulence, drug-testing, and real-time imaging of host-pathogen interactions. Significance StatementThe virulence of many pathogens is dependent on host temperature. We demonstrate that the A. dispar embryo provides an excellent new thermo-relevant alternative to zebrafish and mouse models, which have limitations in terms of the range of temperatures that can be assessed in real-time. In this study, we have assessed C. albicans temperature-based virulence, focusing on human body and human skin temperatures (37, 40 and 30 {degrees}C, respectively) by examining different genetic backgrounds of C. albicans strains. The results indicate different C. albicans strains with genetic background show varied virulence depending on temperature indicating importance of examination of virulence mechanisms at physiological temperatures.

animal behavior and cognition↗

bioRxiv2024

Wheat Enhanced Disease Resistance EMS-Mutants Include Lesion-mimics With Adult Plant Resistance to Stripe Rust

Tetraploid durum wheat Triticum turgidum subsp. durum cv Kronos has extensive genetic variation resources, including a sequenced and cataloged ethyl methanesulfonate (EMS) mutagenized population. To utilize this allelic diversity, we screened over 2,000 mutant lines and identified over 30 enhanced disease resistance (EDR) mutants in a forward genetic field screen against stripe rust. Sixteen of the EDR lines have persistent resistance to stripe rust after four years, and several mutants showed differential disease responses against other fungal pathogens, indicating that the lines possess diverse alleles that affect multiple routes of pathogen suppression. Five of these 16 lines showed spontaneous lesion formation in the absence of pathogens. Only one showed a reduction in kernel weight under pathogen pressure, a testimony to the high mutational density that wheat can tolerate. Phenotypic selection for resistance at the adult stage identified useful EMS alleles for stripe rust resistance. The mutations in the 16 EDR lines were newly mapped to a recently released long-read Kronos genome to enhance their utility in molecular breeding for fungal resistance and for fundamental studies of plant-pathogen interactions.

plant biology↗

bioRxiv2024

Spatial proteomics identifies a novel CRTC-dependent viral sensing pathway that stimulates production of Interleukin-11

Appropriate cellular recognition of viruses is essential for the generation of effective innate and adaptive antiviral immunity. Viral sensors and their signalling components thus provide a crucial first line of host defence. Many exhibit subcellular relocalisation upon activation, triggering expression of interferon and antiviral genes. To identify novel signalling factors we analysed protein relocalisation on a global scale during viral infection. CREB Regulated Transcription Coactivators-2 and 3 (CRTC2/3) exhibited early cytoplasmic-to-nuclear translocation upon a diversity of viral stimuli, in diverse cell types. This movement was depended on Mitochondrial Antiviral Signalling Protein (MAVS), cyclo-oxygenase proteins and protein kinase A. We identify a key effect of transcription stimulated by CRTC2/3 translocation as production of the pro-fibrogenic cytokine interleukin-11. This may be important clinically in viral infections associated with fibrosis, including SARS-CoV-2.

immunology↗

bioRxiv2023

In the murine and bovine maternal mammary gland signal transducer and activator of transcription 3 is activated in clusters of epithelial cells around the day of birth

Signal Transducers and Activators of Transcription (STATs) regulate mammary gland development. Here we investigate the expression of pSTAT3 in the murine and bovine mammary gland around the day of birth. We identify polarisation of mammary alveoli towards either a low- or high-proportion of pSTAT3 positive alveolar epithelial cells. We present localised colocation analysis applicable to other mammary studies where identification, quantification and interrogation of significant, spatially congregated events is required. We demonstrate that pSTAT3-positive events are multifocally clustered in a non-random and statistically significant fashion. This finding represents a new facet of mammary STAT3 biology meriting further functional investigation.

cell biology↗

bioRxiv2023

Discovery of the sEH Inhibitor Epoxykynin as Potent Kynurenine Pathway Modulator

Disease-related phenotypic assays enable unbiased discovery of novel bioactive small molecules and may provide novel insights into physiological systems and unprecedented molecular modes-of-action (MMOA). Herein we report the identification and characterization of epoxykynin, a potent inhibitor of the soluble epoxide hydrolase (sEH). Epoxykynin was discovered by means of a cellular assay monitoring modulation of kynurenine (Kyn) levels in BxPC-3 cells upon stimulation with the cytokine interferon-{gamma} (IFN-{gamma}) and subsequent target identification employing affinity-based chemical proteomics. Increased Kyn levels are associated with immune suppression in the tumor microenvironment and, thus, the Kyn pathway and its key player indoleamine 2,3-dioxygenase 1 (IDO1) are appealing targets in immuno-oncology. However, targeting IDO1 directly has led to limited success in clinical investigations, demonstrating that alternative approaches to reduce Kyn levels are in high demand. We uncover a cross-talk between sEH and the Kyn pathway that may provide new opportunities to revert cancer-induced immune tolerance.

cell biology↗

bioRxiv2022

Multi-lingual multi-platform investigations of online trade in jaguar parts

We conducted research to understand online trade in jaguar parts and develop tools of utility for jaguars and other species. Our research took place to identify potential trade across 31 online platforms in Spanish, Portuguese, English, Dutch, French, Chinese, and Vietnamese. We identified 230 posts from between 2009 and 2019. We screened the images of animal parts shown in search results to verify if from jaguar; 71 posts on 12 different platforms in four languages were accompanied by images identified as definitely jaguar, including a total of 125 jaguar parts (50.7% posts in Spanish, 25.4% Portuguese, 22.5% Chinese and 1.4% French). Search effort varied among languages due to staff availability. Standardizing for effort across languages by dividing number of posts advertising jaguars by search time and number individual searches completed via term/platform combinations, the adjusted rankings of posts were: Portuguese #1, Chinese 2 (time) & 3 (searches), Spanish 3 & 4; French 5 & 4; English 5 & 2, and Dutch 6. Teeth were most common; 156 posts offered at least 367 apparent teeth. From these, 95 teeth were assessed as definitely jaguar; 71 jaguar teeth could be linked to a location, with the majority of the 71 offered for sale from Mexico, China, Bolivia, and Brazil (26.8, 25.4, 16.9, and 12.7% respectively). Ranking of number of teeth was Mexico (19), China (18), Bolivia (12), Brazil (9), Peru/Ecuador (most accurate probable location) (8), Venezuela (3), Guadeloupe (1), and Uruguay (1). The second most traded item, skins and derivative items were only identified from Latin America: Brazil (7), was followed by Peru (6), Bolivia (3), Mexico (2 and 1 skin piece), and Nicaragua and Venezuela (1 each). Whether by number of posts or pieces, the ranking of parts was teeth, skins/pieces of skins, heads, and bodies. Our research presents a snapshot of online jaguar trade and methods that may have utility for many species now traded online. Our research took place within a longer-term project to assist law enforcement in host countries to better identify potential illegal trade online, with research findings informing hubs in Latin America for building such capacity.

ecology↗

bioRxiv2022

Erbb4 deletion from fast-spiking interneurons causes psychosis-relevant neuroimaging phenotypes

Converging lines of evidence suggest that dysfunction of cortical parvalbumin-expressing (PV+) GABAergic interneurons is a core feature of psychosis. This dysfunction is thought to underlie neuroimaging abnormalities commonly found in patients with psychosis, particularly in the hippocampus. These include increases in resting cerebral blood flow (CBF) and levels of glutamatergic metabolites, and decreases in binding of GABAA 5 receptors and the synaptic density marker synaptic vesicle glycoprotein 2A (SV2A). However, direct links between PV+ interneuron dysfunction and these neuroimaging readouts have yet to be established. Conditional deletion of a schizophrenia susceptibility gene, the tyrosine kinase receptor Erbb4, from cortical and hippocampal PV+ interneurons leads to several synaptic, behavioral and cognitive phenotypes relevant to psychosis in mice. Here, we investigated how this PV+ interneuron disruption affects the hippocampal in vivo neuroimaging readouts in the Erbb4 model. Adult Erbb4 conditional mutant mice (Lhx6-Cre;Erbb4F/F, n=12) and their wild-type littermates (Erbb4F/F, n=12) were scanned in a 9.4T magnetic resonance scanner to quantify CBF and glutamatergic metabolite levels (glutamine, glutamate, GABA). Subsequently, we assessed GABAA receptors and SV2A density using quantitative autoradiography. Erbb4 mutant mice showed significantly elevated CBF and glutamine levels, as well as decreased SV2A density compared to wild-type littermates. No significant GABAA receptor density differences were identified. These findings demonstrate that specific disruption of cortical PV+ interneurons in mice recapitulate some of the key neuroimaging findings in psychosis patients, and link PV+ interneuron deficits to non-invasive, translational measures of brain function and neurochemistry that can be used across species.

neuroscience↗