Biology subjects

Ching, J.

Publications and source records attributed to Ching, J..

12 recordsLinked to original sources

bioRxiv2026

Female biases in islet cell gene expression, alpha cell number, and glucagon are present early in postnatal life

Biological sex significantly affects glucose homeostasis. Sex differences in insulin sensitivity in peripheral tissues play a role in this difference; however, a growing body of evidence suggests sex differences in islet cells also contribute to differential glucose homeostasis. Studies in rodent and human models have identified sex differences in alpha- and beta-cell gene expression, in islet cell composition, metabolism, and stress responses, and in circulating levels of glucoregulatory hormones. However, most of these studies used adult humans or mice, leaving the age at which these differences emerge less clear. We performed a detailed characterization of glucose homeostasis and islet biology in young male and female mice from two mouse strains widely used in diabetes research to model both Type 1 (non-obese diabetic, NOD) and Type 2 diabetes (C57BL/6J). We uncovered male-female differences in islet cell gene expression and composition, and in circulating levels of glucagon. Importantly, these differences were reproducible across both models and were present prior to diabetes-like phenotypes. Together, our data suggest sex differences in aspects of islet biology begin early in postnatal life.

physiology↗

bioRxiv2026

The Nematicide Tioxazafen Disrupts Proteasome Function via Cytochrome P450 Bioactivation

Tioxazafen is an effective nematicide whose commercialization was halted because handlers reportedly developed rashes after working with seeds coated with a tioxazafen-laced cocktail. Here, we show that tioxazafen is bioactivated into toxic products by nematode and human cytochrome P450s. Through systematic analyses, we found that bioactivated tioxazafen disrupts proteasome function, leading to the accumulation of the NRF1 transcription factor ortholog SKN-1A in the nematode C. elegans, and a bounce-back transcriptional up-regulation of proteasome components. Genetic upregulation of the C. elegans proteasome supresses tioxazafens lethality, indicating that proteotoxicity is a key contributor to death. A survey of human P450s revealed that skin-expressed CYP1A1 toxifies tioxazafen and may account for the reaction to tioxazafen-coated seeds. We also found that rabbit CYP1A1 fails to bioactivate tioxazafen, which may explain the pre-market failure to detect robust adverse skin reactions. Our work highlights vulnerabilities in pre-market toxicological assays and a provides potential solution to prospectively identifying P450 toxication events. One-Sentence SummaryTioxazafen is bioactivated by cytochrome P450s into a proteasome disruptor.

pharmacology and toxicology↗

bioRxiv2026

A Cross-Species Systems Genetics Framework Identifies Causal Genes in Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of kidney failure in the developed world, but the genetic architecture of DN susceptibility is not well characterised. Here we apply a systems genetics approach in a mouse model of DN to discover novel QTLs for clinically relevant phenotypes including albuminuria, glomerulosclerosis, and macrophage infiltration. For context and prioritisation, we combined single-cell-transcriptomics-guided pQTL and eQTL mapping with cell-type-specific co-expression networks, identifying 192 candidate pGenes for albuminuria. While many were novel, 27% had prior genetic associations, and 40% were validated in a human diabetic cohort. Twelve genes belong to a podocyte network enriched for human GWAS signals. Among those, functional significance of the E3 ubiquitin ligases DCAF6 and ZNRF2 was confirmed by knockdown in Drosophila nephrocytes. Our systems genetics approach identified DN susceptibility genes previously validated in human GWAS while uncovering potential new genes and pathways that could be exploited for risk stratification and therapeutics development.

systems biology↗

bioRxiv2025

Small shifts, big ripples: multi-omics studies reveal how ambient temperatures govern Chlamydomonas cellular responses

Photosynthetic protists, known as microalgae, face increasing temperatures due to climate change. The green biflagellate alga Chlamydomonas reinhardtii serves as a model for thermoregulation. While responses to thermal stress are well characterized, much less is known about the impact of ambient temperature shifts. Understanding microalgal responses to environmental temperature changes is critical, as these primary producers drive ecosystem productivity and food web dynamics. Here, C. reinhardtii grew mixotrophically at ambient temperatures from 18 {degrees}C to 33 {degrees}C. Transcriptomic profiling revealed extensive reorganization, with over 5,000 transcripts significantly affected, including those involved in algal-bacterial interactions, photoreception, lipid metabolism, photosynthesis, cilia formation, and the secretome. CO2 transfer rates and acetate levels measured at 18 {degrees}C and 28 {degrees}C suggest decreased photoautotrophic algal growth at 28 {degrees}C at first. Antagonistic bacterial activity was sustained longer at lower temperatures. Proteomic analyses of isolated cilia and secreted proteins corroborate major abundance changes within these sub-proteomes, particularly in ciliary intraflagellar transport complexes and mating-related proteins in the secretome. Together, these molecular alterations resulted in pronounced changes in growth, the lengths of cells and cilia swimming behavior, mating ability and bacterial antagonism. These data reveal major cellular responses caused by ambient, even short-term temperature shifts.

cell biology↗

bioRxiv2025

Microneedle delivery of stem cell derived retinal pigment epithelial cells

Retinal pigment epithelium (RPE) transplantation surgery has shown potential benefits in animal models and early clinical trials. However, current implantation techniques are limited by the need for large retinotomies when cell bearing scaffolds are used or cellular reflux in the case of cell suspension transplantation with micro-cannulae. Here we demonstrate that it is feasible to pass primary and stem cell derived RPE cells through microneedles with a bore as small as 30m. In vitro, there is no immediate loss of cell viability and this remains true throughout 14 days of live cell viability monitoring. Further, when the RPE cells are cultured over 14 days, they attach within 24 hours and become confluent, with normal morphological appearances. The formation of tight junctions is unimpeded with the typical polygonal pattern observed. The effects of shear stress due to passage of the cells through a small lumen were not evident in cultured cells labelled for the cytoskeletal protein F-actin. RPE cell VEGF secretion is unaffected by microneedle size in primary RPE and iPSC RPE cells. Ex vivo surgical implantation demonstrates that the technique is feasible, RPE cells engraft in the outer retina and we show that vitrectomy is not required to successfully transplant cells. Herein, we provide the first evidence of surgical microneedle cell delivery, which may have future applications more broadly within ophthalmic microsurgery and minimally invasive delivery strategies. Graphical summary O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/651158v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@19ca129org.highwire.dtl.DTLVardef@18c3feorg.highwire.dtl.DTLVardef@1eb6300org.highwire.dtl.DTLVardef@b0c946_HPS_FORMAT_FIGEXP M_FIG C_FIG Induced pluripotent stem cells (iPSC) are differentiated into retinal pigment epithelial cells (iPSC RPE) and cultured for 14 days until confluent. A single cell suspension of iPSC RPE is then injected using an Alcon Constellation Vision System machine through different microneedles into a 48 cell culture plate or in the subretinal space of an ex vivo pig eye 3-6 months in age. Cells and tissues were processed and stained by using various antibodies to assess viability, morphology, function and anatomical localization in the subretinal space to confirm the feasibility of microneedle cell delivery.

cell biology↗

bioRxiv2024

The DJ-1-derived peptide, ND-13, confers cardioprotection by inhibiting mitochondrial fission and preserving mitochondrial bioenergetics via the RhoA-ROCK1-Drp1 pathway

BackgroundAcute myocardial infarction (AMI) and post-infarct heart failure (HF) are among the leading causes of death and disability worldwide. As such, new treatments are urgently needed to protect the heart against the detrimental effects of acute ischemia/reperfusion injury (IRI), in order to prevent the onset of HF and improve clinical outcomes following AMI. Given that mitochondrial dysfunction is a key determinant of IRI-induced cardiomyocyte death in AMI, we investigated ND-13, a 13-amino acid peptide derived from the pro-survival protein DJ-1, as a novel mitoprotective strategy for limiting myocardial infarct size (IS) following AMI. Methods and ResultsIn isolated adult Dendra-2 mice cardiomyocytes subjected to simulated IRI, treatment with ND-13 peptide reduced cell death by 42%, decreased phosphorylation of Drp1 at Ser616 and inhibited mitochondrial fission, improved mitochondrial respiratory function, decreased oxidative stress, and preserved ATP levels. Treatment of cardiomyocytes with ND-13 decreased levels of RhoA and reduced activity of downstream ROCK1, the latter of which is known to phosphorylate Drp1 at Ser616. In ex vivo Langendorff-perfused hearts subjected to IRI, treatment with ND-13 at reperfusion reduced IS by 43%, attenuated oxidative stress and preserved post-infarct cardiac contractile function. Finally, in vivo administration of ND-13 peptide at reperfusion in mice subjected to acute myocardial IRI reduced IS by 35% at 72-hours of reperfusion, and restored mitochondrial bioenergetics in cardiomyocytes isolated from the area-at-risk following 2-hours reperfusion as evidenced by preservation of key metabolites involved in glucose oxidation and fatty acid oxidation. The cardioprotective phenotype translated to improved cardiac function and less adverse left ventricular remodelling at 28 days post-infarction. ConclusionsWe show for the first time the mitoprotective effects of the DJ-1-derived peptide, ND-13, administered at the onset of reperfusion following AMI. We found that ND-13 protects mitochondria by inhibiting IRI-induced mitochondrial fission and preserved mitochondrial function following IRI via the RhoA-ROCK-Drp1 pathway. These findings highlight ND-13 as a novel mitoprotective agent which has the therapeutic potential for limiting IS and preventing HF in patients with AMI. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABSO_LIAdministration of the DJ-1-derived peptide, ND-13, at the onset of reperfusion reduced myocardial infarct size and preserved cardiac contractile function following acute myocardial ischemia/reperfusion injury (IRI). C_LIO_LIThe cardioprotective effect of ND-13 treatment was mediated by inhibition of IRI-induced mitochondrial fission and improvement in mitochondrial bioenergetics via the RhoA-ROCK-Drp1 pathway. C_LI What are the Clinical Implications?O_LITreatment with ND-13 peptide at the onset of reperfusion has the therapeutic potential to reduce myocardial infarct size and prevent the onset of heart failure in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention. C_LI

physiology↗

bioRxiv2023

Diverse Plant-Parasitic Nematodes are Selectively Killed by Oxadiazole Thioether Pro-Nematicides

Left unchecked, plant-parasitic nematodes have the potential to devastate crops globally. Highly effective but non-selective nematicides are justifiably being phased-out, leaving farmers with limited options for managing nematode infestation. Here, we report our discovery of a 1,3,4-oxadiazole thioether scaffold called Cyprocide that selectively kills diverse plant-parasitic nematodes. Cyprocide is bioactivated into a lethal reactive electrophilic metabolite by specific nematode cytochrome P450 enzymes. Because Cyprocide fails to kill non-target organisms, we infer that the targeted lethality of this pro-nematicide derives from P450 substrate selectivity. Our findings demonstrate that Cyprocide is a selective nematicidal scaffold with broad-spectrum activity that holds the potential to help safeguard our global food supply.

genetics↗

bioRxiv2022

Pneumatic Controlled Nano-Sieve for Efficient Capture and Release of Nanoparticles

A pneumatic controlled nano-sieve device is demonstrated for the efficient capture and release of 15 nm quantum dots. This device consists of a 200 nm deep glass channel and a PDMS-based pneumatic pressure layer to enhance target capture. The fluid motion inside the nano-sieve is studied by computational fluidic dynamics (CFD) and microfluidic experiments, enabling efficient target capture with a flow rate as high as 100 L/min. In addition, micro-grooves are fabricated inside the nano-sieve to create low flow rate regions, which further improves the target capture efficiency. A velocity contour plot is constructed with CFD, revealing the flow rate is lowest at the top and bottom of the micro-grooves. This phenomenon is supported by the observed nanoparticle clusters surrounding the micro-grooves. By changing the morphology and pneumatic pressure, this device will also facilitate rapid capture and release of various biomolecules.

bioengineering↗

bioRxiv2022

Nemacol is a Small Molecule Inhibitor of C. elegans Vesicular Acetylcholine Transporter with Anthelmintic Potential

Nematode parasites of humans and livestock pose a significant burden to human health, economic development, and food security. Anthelmintic drug resistance is widespread among parasites of livestock and many nematode parasites of humans lack effective treatments. Here, we present a nitrophenyl-piperazine scaffold that induces motor defects rapidly in the model nematode Caenorhabditis elegans. We call this scaffold Nemacol and show that it inhibits the vesicular acetylcholine transporter (VAChT), a target recognized by commercial animal and crop health groups as a viable anthelmintic target. We demonstrate that it is possible to create Nemacol analogs that maintain potent in vivo activity whilst lowering their affinity to the mammalian VAChT 10-fold. We also show that Nemacol synergizes with the anthelmintic ivermectin to kill C. elegans. Hence, Nemacol represents a promising new anthelmintic scaffold that acts through an identified viable anthelmintic target. One sentence summaryA small molecule screen identifies a vesicular acetylcholine transporter inhibitor scaffold that incapacitates parasitic nematodes

pharmacology and toxicology↗

bioRxiv2021

The novel conserved NAD+ binding micropeptide SGHRT regulates mitochondrial function and metabolism in human cardiomyocytes

AbstractsNicotinamide adenine dinucleotide (NAD) is a critical metabolite and coenzyme for multiple metabolic pathways and cellular processes (1-4). In this study, we identified Singheart, SGHRT as a nuclear genome-encoded NAD+-binding mitochondrial micropeptide. SGHRT, present in both monomeric and dimeric forms, binds directly to NAD, but not NADH or flavin adenine dinucleotide (FAD). Localized to the inner mitochondrial membrane and mitochondrial matrix, SGHRT interacts with the mitochondrial enzymes Succinate-CoA Ligase and Succinate Dehydrogenase. SGHRT deletion in human embryonic stem cell derived cardiomyocytes disrupted mitochondria morphology, decreased total NAD and ATP abundance, and resulted in defective TCA cycle metabolism, the electron transport chain and in Ox-Phos processes. These results comprise the first report of an NAD+-binding micropeptide, SGHRT, required for mitochondrial function and metabolism.

cell biology↗

bioRxiv2020

Glioblastoma Cell Migration is Directed by Electrical Signals

BackgroundElectric field (EF) directed cell migration (electrotaxis) is known to occur in glioblastoma multiforme (GBM) and neural stem cells, with key signaling pathways frequently dysregulated in GBM. One such pathway is EGFR/PI3K/Akt, which is down-regulated by peroxisome proliferator activated receptor gamma (PPAR{gamma}) agonists. We investigated the effect of electric fields on GBM differentiated and stem cell migration and whether this was affected by treatment with the PPAR{gamma} agonist pioglitazone. MethodsPrimary GBM cell lines were cultured as differentiated and glioma stem cells (GSCs) and then exposed to EFs using electrotaxis chambers and imaged with time lapse microscopy. Cells were then treated with varying concentrations of pioglitazone and/or its inhibitor GW9662 and their responses to EFs examined. ResultsWe demonstrated that GBM differentiated and GSCs have opposing preferences for anodal and cathodal migration, respectively. Pioglitazone treatment resulted in significantly decreased directed cell migration in both cell types. Western blot analysis did not demonstrate any change in PPAR{gamma} expression with and without exposure to EF. ConclusionsOpposing EF responses in primary GBM differentiated cells and GSCs can be inhibited chemically by pioglitazone, implicating GBM EF modulation as a potential target in preventing tumour recurrence.

cancer biology↗

bioRxiv2019

Metabolic stress is a primary pathogenic event in transgenic Caenorhabditis elegans expressing neuronal human amyloid-β

Alzheimers disease (AD) is the most common neurodegenerative disease affecting the elderly worldwide. Mitochondrial dysfunction has been proposed as a key event in the etiology of AD. We have previously modeled amyloid-beta (A{beta})-induced mitochondrial dysfunction in a transgenic Caenorhabditis elegans strain by expressing human A{beta} peptide specifically in neurons (GRU102). Here, we focus on a deeper analysis of these metabolic changes associated with A{beta}-induced mitochondrial dysfunction. Integrating metabolomics, transcriptomics, biochemical studies and computational modeling, we identify alterations in Tricarboxylic Acid (TCA) cycle metabolism following even low-level A{beta} expression. In particular, GRU102 show reduced activity of a rate-limiting TCA cycle enzyme, alpha-ketoglutarate dehydrogenase. These defects are associated with elevation of protein carbonyl content specifically in mitochondria. Importantly, metabolic failure occurs before any significant increase in global protein aggregate is detectable. Treatment with an antidiabetes drug, Metformin, reverses A{beta}-induced metabolic defects, reduces protein aggregation and normalizes the lifespan of GRU102. Our results point to metabolic dysfunction as an early and causative event in AD pathology and a promising target for intervention.

neuroscience↗