Biology subjects

Cho, H.-J.

Publications and source records attributed to Cho, H.-J..

10 recordsLinked to original sources

bioRxiv2026

Generation of Human Taste Bud Organoids as a Human-Mimetic Platform for Modeling Taste Perception

We established a human taste bud organoid system derived from circumvallate papillae. This model has been highly anticipated in the field of taste research, where feasible approaches for validating taste biology discovered in rodent models have been limited. Through a stepwise exploratory strategy, we systematically identified and optimized the niche factors required to maintain taste bud organoids and promote their differentiation. This human taste bud organoid system comprises Type I-IV taste receptor cells (TRCs) as well as stem/progenitor cells, and its sensory receptor cells exhibit calcium responses to taste stimuli. Using this system, we identified robust Wnt signaling as a requirement for optimal TRC fate progression, uncovered a human-specific transcriptional program in LGR5 cells, and identified previously unrecognized molecular markers for Type I TRCs. By recapitulating native human taste bud cell diversity and function, this organoid provides a tractable platform for studying human taste biology and dysfunction.

developmental biology↗

bioRxiv2025

Optimizing the In Vitro Neuronal Microenvironment to Mitigate Phototoxicity in Live-cell Imaging

Long-term imaging formats are ideal for capturing dynamic neuronal network formation in vitro, yet fluorescent techniques are often constrained by the impact of phototoxicity on cell survival. Here we present a live-imaging protocol that was optimised via quantitative analysis of 3 target culturing conditions on neuromorphological health: extracellular matrix (human- versus murine-derived laminin), culture media (Neurobasal versus Brainphys Imaging media), and seeding density (1x105 versus 2x105 cells/cm2). A cortical neuron reporter line was differentiated from human embryonic stem cells by transduction of Neurogenin-2 and green fluorescent protein, then fluorescently imaged in 8 different microenvironments daily for 33 days. Alongside viability analysis by PrestoBlue assay and gene quantification by digital polymerase chain reaction, an automated image analysis pipeline was developed to characterise network morphology and organisation over time. Brainphys Imaging medium was observed to support neuron viability, outgrowth, and self-organisation to a greater extent than Neurobasal medium with either laminin type, while the combination of Neurobasal medium and human laminin reduced cell survival. Further, a higher seeding density fostered somata clustering, but did not significantly extend viability compared to low density. These findings suggest a synergistic relationship between species-specific laminin and culture media in phototoxic environments, which is positively mediated by light-protective compounds found in Brainphys Imaging medium.

cell biology↗

bioRxiv2024

Spatiotemporal regulation by downstream genes of Prok2 in olfactory system: from development to function

Olfaction is important for the quality of life; however, in Kallmann syndrome (KS), defective development results in olfactory dysfunction. The mechanism underlying olfactory development, especially in the olfactory epithelium (OE), which detects olfactory signals, remains unclear. Mutations in PROK2, which encodes prokineticin-2, occur in approximately 9% of the KS patients with olfactory defects. In this study, we examined olfactory function and analyzed the causes of olfactory dysfunction based on spatiotemporal development and gene expression changes in Prok2 knockout (KO) model mice with KS. Adult Prok2 KO mice exhibited reduced ability to detect olfactory signals. Maturation of olfactory sensory neurons (OSNs) in the OE and formation of glomeruli in the olfactory bulb (OB) in adult Prok2 KO mice were disrupted, thus causing olfactory dysfunction. Molecular analysis of Prok2 KO mice during embryonic development revealed abnormal development of OB layers and reduced differentiation to mature OSNs in the OE, which caused defects in the entire olfactory system. Downstream signaling genes of Prok2, including intermediate filament genes and genes expressed in the putative OB, mediated olfactory system organization. Our findings reveal the role of Prok2 in olfactory system organization, providing insights into the mechanisms through which olfactory development defects translate to olfactory function.

developmental biology↗

bioRxiv2024

Neuron-derived Prox1 suppresses injury-induced reprogramming of Muller glia to proliferative retinal progenitor cells

Individuals with retinal degenerative diseases face significant obstacles in restoring normal vision due to the inability to regenerate degenerated retinal cells. While retinal neurons can be regenerated from Muller glia (MG) in cold-blooded vertebrates, this regenerative ability is lacking in mammals, indicating the limited competence of mammalian MG for retinal regeneration. In this study, we elucidate the role of prospero-related homeobox 1 (Prox1) in rendering the mammalian retina incompetent for MG-derived regeneration. Prox1 accumulates in MG in the degenerating human and mouse retinas but not in those in the regenerating zebrafish retina. Strikingly, Prox1 in mouse MG originated from neighboring retinal neurons through intercellular protein transfer. Consequently, inhibition of Prox1 transfer to MG enables the reprogramming of MG into proliferative retinal progenitor cells in injured mouse retinas. Furthermore, we succeeded in regenerating retinal neurons and delaying vision loss in retinitis pigmentosa disease model in mice by adenoassociated viral gene delivery of an anti-Prox1 antibody that sequesters extracellular Prox1 in the mouse retina. Taken together, our findings highlight the therapeutic potential of anti-Prox1 therapy in restoring the regenerative potential of the mammalian retina.

developmental biology↗

bioRxiv2023

Homeostatic Dysregulation of Systemic CD8+ T Cell Compartment in Lung Cancer Patients

Cancer adapts various resistance mechanisms to counteract CD8+ T cell attacks. While this suppression of antigen-specific CD8+ T cells is common within the tumor microenvironment, little is known about how tumors affect CD8+ T cells systemically. Here we show a new link between tumor-associated homeostatic dysregulation and uncontrolled differentiation of peripheral blood CD8+ T cells. These CD8+ T cells exhibited progressive alterations indicative of diminished quiescence, increased spontaneous activation, and more-differentiated proliferation-incompetent effector cells. This phenomenon was not limited to tumor-reactive cells but broadly applicable to non-specific cells, correlating with poor clinical responses to immune checkpoint inhibitor therapy. These findings provide a new mechanism by which cancer impairs CD8+ T cells by dysregulating the homeostasis of systemic CD8+ T cell populations. One-Sentence SummaryCancer-associated homeostatic dysregulation accelerates uncontrolled differentiation of systemic CD8+ T cells.

immunology↗

bioRxiv2023

Mefloquine-induced conformational shift in Cx36 N-terminal helix leading to channel closure mediated by lipid bilayer

Connexin 36 (Cx36) forms interneuronal gap junctions, establishing electrical synapses for rapid synaptic transmission. In disease conditions, inhibiting Cx36 gap junction channels (GJCs) is beneficial, as it prevents abnormal synchronous neuronal firing and apoptotic signal propagation, mitigating seizures and progressive cell death. Here, we present cryo-electron microscopy structures of human Cx36 GJC in complex with known channel inhibitors, such as mefloquine, arachidonic acid, and 1-hexanol. Notably, these inhibitors competitively bind to the binding pocket of the N-terminal helices (NTH), inducing a conformational shift from the pore-lining NTH (PLN) state to the flexible NTH (FN) state. This leads to the obstruction of the channel pore by flat double-layer densities of lipids. These studies elucidate the molecular mechanisms of how Cx36 GJC can be modulated by inhibitors, providing valuable insights into potential therapeutic applications.

biochemistry↗

bioRxiv2022

A high-throughput cytotoxicity screening platform reveals agr-independent mutations in bacteraemia-associated Staphylococcus aureus that promote intracellular persistence

Staphylococcus aureus infections are associated with high mortality rates. Often considered an extracellular pathogen, S. aureus can persist and replicate within host cells, evading immune responses and causing host cell death. Classical methods for assessing S. aureus cytotoxicity are limited by testing culture supernatants and endpoint measurements that do not capture the phenotypic diversity of intracellular bacteria. Using a well-established epithelial cell line model, we have developed a platform called InToxSa (Intracellular Toxicity of S. aureus) to quantify intracellula cytotoxic S. aureus phenotypes. Studying a panel of 387 S. aureus bacteraemia isolates, and combined with comparative, statistical and functional genomics, our platform identified mutations in S. aureus clinical isolates that reduced bacterial cytotoxicity and promoted intracellular persistence. In addition to numerous convergent mutations in the Agr quorum sensing system, our approach detected mutations in other loci that also impacted cytotoxicity and intracellular persistence. We discovered that clinical mutations in ausA, encoding the aureusimine non-ribosomal peptide synthetase, reduced S. aureus cytotoxicity and increased intracellular persistence. InToxSa is a versatile, high-throughput cell-based phenomics platform and we showcase its utility by identifying clinically relevant S. aureus pathoadaptive mutations that promote intracellular residency.

microbiology↗

bioRxiv2022

POU6F2 mutation identified in humans with pubertal failure shifts isoform formation and alters GnRH transcript expression

Idiopathic hypogonadotropic hypogonadism (IHH) is characterized by absent pubertal development and infertility, often due to gonadotropin-releasing hormone (GnRH) deficits. Exome sequencing of two independent cohorts of IHH patients identified 12 rare missense variants in POU6F2. POU6F2 encodes two distinct isoforms. In mouse, pituitary and gonads expressed both isoforms, but only isoform1 was detected in GnRH cells. Although the function of isoform2 is well known, using bioinformatics and cells assays on a human-derived GnRH cell line, we demonstrate isoform1 can also act as a transcriptional regulator, decreasing GNRH1 expression. The impact of two POU6F2 variants (MT1 and MT2) was then examined. MT1, but not MT2, reduced transcriptional activity of either isoform, preventing Hes5 promoter activation by isoform2 and repression of GnRH transcripts by isoform1. GnRH transcription increases as the cells migrate into the brain. Augmentation earlier can disrupt normal GnRH cell migration, consistent with POU6F2 variants contributing to IHH pathogenesis.

genetics↗

bioRxiv2021

Efficient, selectable marker free gene targeting in soybean using novel Ochrobactrum haywardense-mediated delivery

We report robust selectable marker-free gene targeting (GT) system in soybean, one of the most economically important crops. A novel efficient Ochrobactrum haywardense-mediated embryonic axis transformation method was used for the delivery of CRISPR-Cas9 components and donor template to regenerate T0 plants in 6-8 weeks after transformation. This approach generated up to 3.4% targeted insertion of the donor sequence into the target locus in T0 plants, with [~] 90% mutation rate observed at the genomic target site. The GT was demonstrated in two genomic sites using two different donor DNA templates without a need of a selectable marker within the template. High-resolution Southern by Sequencing (SbS) analysis identified T1 plants with precise targeted insertion and without unintended plasmid DNA. Unlike previous low-frequency GT reports in soybean that involved particle bombardment-mediated delivery and extensive selection, the method described here is fast, efficient, reproducible, does not require selectable marker within the donor DNA, and generates non-chimeric plants with heritable GT.

plant biology↗

bioRxiv2018

Vascular defects of DYRK1A knockouts are ameliorated by modulating calcium signaling in zebrafish

DYRK1A is a major causative gene in Down syndrome (DS). Reduced incidence of solid tumors and vascular anomalies in DS patients suggests a role of DYRK1A in angiogenesis, but in vivo evidence is lacking. Here, we used zebrafish dyrk1aa mutant embryos to understand DYRK1A function in the cerebral vasculature formation. Zebrafish dyrk1aa mutants exhibited cerebral hemorrhage and defects in angiogenesis of central arteries in the developing hindbrain. Such phenotypes were rescued by wild-type dyrk1aa mRNA, but not by a kinase-dead form, indicating the importance of DYRK1A kinase activity. Chemical screening using a bioactive small molecule library identified a calcium chelator, EGTA, as one of the hits that most robustly rescued the hemorrhage. Vascular defects of mutants were also rescued by independent modulation of calcium signaling by FK506. Furthermore, the transcriptomic analyses supported the alterations of calcium signaling networks in dyrk1aa mutants. Together, our results suggest that dyrk1aa plays an essential role in angiogenesis and in maintenance of the developing cerebral vasculature via regulation of calcium signaling, which may have therapeutic potential for DYRK1A-related vascular diseases.

developmental biology↗