Biology subjects

Choi, J.-Y.

Publications and source records attributed to Choi, J.-Y..

13 recordsLinked to original sources

bioRxiv2026

Primary tumor transcriptomic signature is associated with locoregional dissemination in canine mammary carcinoma

Canine mammary carcinoma (CMC) exhibits heterogeneous metastatic behavior, while accurate assessment of locoregional dissemination may be limited by incomplete sampling, occult metastasis, and variable sentinel lymph node anatomy. We investigated whether primary-tumor transcriptomic programs are associated with locoregional dissemination. The training cohort comprised 113 CMC RNA sequencing samples classified by peritumoral lymphatic vessel invasion, and the independent evaluation cohort comprised 27 microarray samples classified by histopathologically confirmed lymph node (LN) metastasis. Expression profiles were mapped to human ortholog gene symbols, and single-sample gene set enrichment analysis (ssGSEA) was performed using Molecular Signatures Database (MSigDB) gene sets. Seven candidate gene sets selected through univariable screening and literature-guided curation were entered into least absolute shrinkage and selection operator (LASSO) logistic regression, yielding a four-gene-set transcriptomic risk score (RS). The RS showed an apparent receiver operating characteristic area under the curve (ROC-AUC) of 0.949 (95% confidence interval, 0.906-0.993) and precision-recall area under the curve (PR-AUC) of 0.725 in the training cohort; bootstrap internal validation yielded an optimism-corrected ROC-AUC of 0.920. In the evaluation cohort, the ROC-AUC was 0.890 (95% confidence interval, 0.766-1.000) and PR-AUC was 0.869. Discrimination was attenuated but retained in histologically restricted sensitivity analyses, and higher RS remained associated with locoregional dissemination after clinicopathologic adjustment. These findings support gene-set-level transcriptomic scoring as a potential complementary approach for characterizing dissemination-associated primary-tumor states in CMC.

cancer biology↗

bioRxiv2026

4-Hexylresorcinol Enhances Skeletal Muscle Glucose Handling through the AMPK-GLUT4 axis in Diabetic Rats

BackgroundSkeletal muscle insulin resistance in diabetes is characterized by impaired GLUT4 availability and dysregulated AMP-activated protein kinase (AMPK) signaling. We investigated whether 4-hexylresorcinol (4HR) modulates glucose metabolism and AMPK-acetyl-CoA carboxylase (ACC)-GLUT4 signaling in vitro and in streptozotocin (STZ)-induced diabetic rats. MethodsDifferentiated C2C12 myotubes were treated with 4HR (0.1-10 {micro}M) and assessed for glucose uptake, GLUT4 translocation, protein stability, proteasome involvement, and AMPK/ACC phosphorylation. In vivo, streptozotocin (STZ)-induced diabetic rats received subcutaneous 4HR (10 mg{middle dot}kgL{superscript 1}, 5 times/week for 7 weeks). Glycemic control, insulin secretion, muscle glycogen content, and serum protein profiles were evaluated. Results4HR markedly increased glucose uptake (>5-fold vs. control, p<0.05), accompanied by increased phosphorylation of AMPK (Thr172) and ACC (Ser79), and redistribution of GLUT4 toward the cell periphery. Cycloheximide chase and proteasome inhibition experiments indicated partial stabilization of GLUT4. In diabetic rats, 4HR reduced fasting glycemia, improved glucose tolerance, elevated circulating insulin, and restored glycogen-rich fibers in skeletal muscle. Serum profiling revealed a metabolic and anti-inflammatory shift, with increased AMPK, p-ACC, GLUT1, LGR4, LDHA, and PGC-1, alongside suppression of NF-{kappa}B and TNF-. Conclusion4HR improves skeletal muscle glucose metabolism in STZ-induced diabetes, associated with activation of AMPK-ACC signaling, preservation of GLUT4 expression, and restoration of glycogen content. These findings highlight 4HR as a promising candidate for further investigation in diabetic muscle dysfunction and metabolic disease.

molecular biology↗

bioRxiv2025

FAM84B facilitates tau propagation via RYR3-mediated exocytosis in response to neuroinflammation

The increasing prevalence of dementia underscores the pressing need for effective therapeutic interventions. Despite extensive research into A{beta}, the limited efficacy of existing treatment modalities necessitates a paradigm shift toward tau pathology including tau propagation to slow dementia progression. Here, we identified a novel protein, FAM84B (also known as LRATD2), involved in tau propagation. Elevated FAM84B levels were detected in the postmortem cortex, cerebrospinal fluid, and induced pluripotent stem cell-derived cortical neurons of patients with tauopathy. FAM84B facilitates tau secretion through exosome assembly and RYR3-mediated exocytosis, followed by exosomal uptake into neighboring cells via clathrin-mediated endocytosis, thereby driving tau propagation. We confirmed that neuroinflammation induced by heightened STAT3 activity and cytokine treatment upregulated FAM84B expression, stimulating tau propagation, as evidenced by reduced propagation upon RYR3 inhibition. These findings provide invaluable insights into potential avenues for targeting tau propagation to ameliorate disease progression in tauopathies.

neuroscience↗

bioRxiv2024

Development of a p62 biodegrader for autophagy targeted degradation

Harnessing autophagy for targeted degradation is a promising extension to proteasome-based targeted protein degradation because of the capacity and versatility of lysosomes to degrade large and complex cargo, thus broadening the scope of therapeutic targets. While small-molecule degraders recruiting the autophagy machinery to targets are starting to emerge, it remains unclear which component of the autophagy lysosomal pathway is most efficacious to induce selective target degradation. Here, we describe two orthogonal induced-proximity strategies to identify and prioritize autophagy effectors that are sufficient to degrade organelles as well as soluble targets. We show that induced proximity of different effectors such as autophagy cargo receptors, ATG8-like proteins or the kinases ULK1 and TBK1 are sufficient to trigger mitophagy. In contrast, self-oligomerizing autophagy cargo receptors outperform ATG8- like effectors and autophagy-related kinases in clearing a soluble cytosolic protein. We further explore the importance of avidity for targeted degradation via autophagy and reveal that the PB1 domain of p62 fused to a LIR peptide is a minimal degron to induce the degradation of mitochondria as well as cytosolic proteins. By developing a novel and highly selective intrabody against the autophagy cargo receptor p62 into a heterobifunctional degrader, we demonstrate that recruitment of endogenous p62 is sufficient to clear mitochondria. This biodegrader, however, is unable to induce degradation of soluble cytosolic proteins due to its inhibitory effect on p62 self-oligomerization. Our study highlights the importance of avidity and suggests that autophagy cargo receptors are attractive entry points for the development of heterobifunctional degraders for complex targets such as organelles or protein aggregates.

synthetic biology↗

bioRxiv2024

DAB-APT: a Fluorescence-Based Assay for Determining Aminopropyl Transferase Activity and Inhibition

Polyamines are polycationic molecules that are crucial in a wide array of cellular functions. Their biosynthesis is mediated by aminopropyl transferases (APTs), promising targets in antimicrobial, antineoplastic and antineurodegenerative therapies. A major limitation, however, is the lack of high-throughput assays to measure their activity. We developed the first fluorescence-based assay, DAB-APT, for measurement of APT activity using 1,2-diacetyl benzene, which forms fluorescent conjugates with putrescine, spermidine and spermine with fluorescence intensity increasing with increasing carbon chain length. The assay has been validated using APT enzymes from S. cerevisiae and P. falciparum and is suitable for high-throughput screening of large chemical libraries. Given the importance of APTs in infectious diseases, cancer and neurobiology, our DAB-APT assay has broad applications, holding promise for advancing research and drug discovery efforts.

biochemistry↗

bioRxiv2024

Phospholipase C β4 promotes RANKL-dependent osteoclastogenesis by interacting with MKK3 and p38 MAPK

Phospholipase C beta (PLC{beta}) exerts diverse biological processes, including inflammatory responses and neurogenesis; however, its role in bone cell function is largely unknown. Among the PLC{beta} isoforms ({beta}1-{beta}4), we found that PLC{beta}4 was most highly upregulated during osteoclastogenesis. In this study, we used global knockout and osteoclast lineage-specific PLC{beta}4 conditional knockout (LysM-PLC{beta}4-/-) mice and demonstrated that PLC{beta}4 is a crucial regulator of receptor activator of nuclear factor {kappa}B ligand (RANKL)-induced osteoclast differentiation. Deletion of PLC{beta}4, both globally and in the osteoclast lineage, resulted in a significant reduction in osteoclast formation and the downregulation of osteoclast marker genes. Importantly, LysM-PLC{beta}4-/- male mice exhibited greater bone mass and a lower number of osteoclasts in vivo than their wild-type littermates, without altering osteoblast function. Mechanistically, we found that PLC{beta}4 forms a complex with p38 mitogen-activated protein kinase (MAPK) and MAPK kinase 3 (MKK3) in response to RANKL, thereby modulating p38 activation. An immunofluorescence assay further confirmed the colocalization of PLC{beta}4 with p38 after RANKL exposure. Moreover, p38 activation rescued the impaired osteoclast formation and restored the reduced p38 phosphorylation due to PLC{beta}4 deficiency. Thus, our findings reveal that PLC{beta}4 controls osteoclastogenesis via the RANKL-dependent MKK3-p38 MAPK pathway, and PLC{beta}4 may be a potential therapeutic candidate for bone diseases such as osteoporosis.

cell biology↗

bioRxiv2024

Dimeric R25CPTH(1-34) Activates the Parathyroid Hormone-1 Receptor in vitro and Stimulates Bone Formation in Osteoporotic Female Mice

Osteoporosis, characterized by reduced bone density and strength, increases fracture risk, pain, and limits mobility. Established therapies of Parathyroid hormone (PTH) analogs effectively promote bone formation and reduce fractures in severe osteoporosis, but their use is limited by potential adverse effects. In the pursuit of safer osteoporosis treatments, we investigated R25CPTH, a PTH variant wherein the native arginine at position 25 is substituted by cysteine. These studies were prompted by our finding of high bone mineral density in a hypoparathyroidism patient with the R25C homozygous mutation, and we explored its effects on PTH type-1 receptor (PTH1R) signaling in cells and bone metabolism in mice. Our findings indicate that R25CPTH(1-84) forms dimers both intracellularly and extracellularly, and the synthetic dimeric peptide, R25CPTH(1-34), exhibits altered activity in PTH1R-mediated cAMP response. Upon a single injection in mice, dimeric R25CPTH(1-34) induced acute calcemic and phosphaturic responses comparable to PTH(1-34). Furthermore, repeated daily injections increased calvarial bone thickness in intact mice and improved trabecular and cortical bone parameters in ovariectomized (OVX) mice, akin to PTH(1-34). The overall results reveal a capacity of a dimeric PTH peptide ligand to activate the PTH1R in vitro and in vivo as PTH, suggesting a potential path of therapeutic PTH analog development.

genomics↗

bioRxiv2023

Vitamin B5 Metabolism is Essential for Vacuolar and Mitochondrial Integrity and Xenobiotic Detoxification in Fungi

Fungal infections, a leading cause of mortality among eukaryotic pathogens, pose a growing global health threat due to the rise of drug-resistant strains. New therapeutic strategies are urgently needed to combat this challenge. The PCA pathway for biosynthesis of Co-enzyme A (CoA) and Acetyl-CoA (AcCoA) from vitamin B5 (pantothenic acid) has been validated as an excellent target for the development of new antimicrobials against fungi and protozoa. The pathway regulates key cellular processes including metabolism of fatty acids, amino acids, sterols, and heme. In this study, we provide genetic evidence that disruption of the PCA pathway results in a significant alteration in the susceptibility of fungi to a wide range of xenobiotics, including clinically approved antifungal drugs through alteration of vacuolar integrity and drug detoxification. The drug potentiation-mediated by genetic regulation of genes in the PCA pathway could be recapitulated using the pantazine analog PZ-2891 as well as the celecoxib derivative, AR-12 through inhibition of fungal AcCoA synthase activity. Collectively, the data validate the PCA pathway as a suitable target for enhancing the efficacy and safety of current antifungal therapies.

microbiology↗

bioRxiv2022

Peroxiredoxin 5 regulates osteogenic differentiation via interaction with hnRNPK during bone regeneration

Peroxiredoxin 5 (Prdx5) is involved in pathophysiological regulation via the stress-induced cellular response. However, the function of Prdx5 in the bone remains largely unknown. Here, we show that Prdx5 is involved in osteoclast and osteoblast differentiation, resulting in osteoporotic phenotypes in Prdx5 knockout (Prdx5Ko) mice. Through immunoprecipitation and liquid chromatography combined with tandem mass spectrometry analysis, heterogeneous nuclear ribonucleoprotein K (hnRNPK) was identified as a potential binding partner of Prdx5 during osteoblast differentiation in vitro. We found that Prdx5 acts as a negative regulator of hnRNPK-mediated osteocalcin (Ocn) expression. In addition, transcriptomic analysis revealed that in vitro differentiated osteoclasts from the bone marrow-derived macrophages of Prdx5Ko mice showed enhanced expression of several osteoclast-related genes. These findings indicate that Prdx5 might contribute to the maintenance of bone homeostasis by regulating osteoblast differentiation. This study proposes a new function of Prdx5 in bone remodeling that may be used in developing therapeutic strategies for bone diseases.

cell biology↗

bioRxiv2022

Spatial Transcriptomics-based Identification of Molecular Markers for Nanomedicine Distribution in Tumor Tissue

The intratumoral accumulation of nanomedicine has been considered a passive process, referred to as the enhanced permeability and retention (EPR) effect. Recent studies have suggested that the tumor uptake of nanomedicines follows an energy-dependent pathway rather than being a passive process. Herein, to explore the factor candidates that are associated with nanomedicine tumor uptake, we developed a molecular marker identification platform by integrating microscopic fluorescence images of a nanomedicine distribution with spatial transcriptomics (ST) information. When this approach is applied to PEGylated liposomes, molecular markers related to hypoxia, glucose metabolism and apoptosis can be identified as being related to the intratumoral distribution of the nanomedicine. We expect that our method can be applied to explain the distribution of a wide range of nanomedicines and that the data obtained from this analysis can enhance the precise utilization of nanomedicines.

bioinformatics↗

bioRxiv2020

Systematic identification of a nuclear receptor-enriched predictive signature for erastin-induced ferroptosis

Erastin, which has been initially identified as a synthetic lethal compound against cancer expressing an RAS oncogene, inhibits cystine/glutamate antiporters and causes ferroptic cell death in various cell types, including therapy-resistant mesenchymal cancer cells. However, despite recent emerging evidence for the mechanisms underlying ferroptosis, molecular biomarkers associated with erastin-dependent ferroptosis have not yet been identified. In the present study, we employed isogenic lung cancer cell models with therapy-resistant mesenchymal properties to show that a redox imbalance leads to glutathione depletion and ferroptotic cell death. Subsequent gene expression analysis of pan-cancer cell lines revealed that the activity of transcription factors, including nuclear factor erythroid 2-related factor 2 (NRF2) and aryl hydrocarbon receptor (AhR), serve as important markers of erastin resistance. Based on the integrated expression of genes in the nuclear receptor meta-pathway (NRM), we constructed an NRM model and validated its robustness using an independent pharmacogenomics dataset. The NRM model was further evaluated by employing it in the sensitivity testing of nine cancer cell lines for which erastin sensitivities had not yet been undetermined. Our pharmacogenomics approach has the potential to pave the way for the efficient classification of patients for therapeutic intervention using erastin or erastin analogs.

systems biology↗

bioRxiv2018

Evaluating causal associations between previously reported risk factors and epithelial ovarian cancer: a Mendelian randomization analysis

BackgroundPreviously reported observational associations between risk factors and epithelial ovarian cancer (EOC) could reflect residual confounding, reverse causation, or measurement error. Mendelian randomization (MR) uses genetic variants as proxies for modifiable risk factors to strengthen causal inference in observational studies.\n\nMethodsWe used MR to evaluate the causal role of 13 previously reported risk factors in overall and histotype-specific EOC in up to 25,509 case subjects and 40,941 controls in the Ovarian Cancer Association Consortium. Inverse-variance weighted models were employed to generate effect estimates and MR-Egger, weighted median, and weighted mode were performed to examine evidence of horizontal pleiotropy. A Bonferroni-corrected P-value threshold was used to establish \"strong evidence\" (P<0.0038) and \"suggestive evidence\" (0.0038<P<0.05) for associations.\n\nResultsThere was strong or suggestive evidence that 9 of 13 risk factors were causally associated with overall or histotype-specific EOC. Genetic liability to endometriosis was strongly associated with EOC (OR per log odds higher liability: 1.27,95%CI:1.16-1.40;P=6.94x10-7) and lifetime smoking exposure was suggestively associated with EOC (OR per unit increase in smoking score:1.36,95%CI:1.04-1.78;P=0.02). In histotype-stratified analyses, the strongest associations found were between: height and clear cell carcinoma (OR per SD increase:1.36,95%CI:1.15-1.61;P=0.0003); age at natural menopause and endometrioid carcinoma (OR per year later onset:1.09,95% CI:1.02-1.16;P=0.007); and genetic liability to polycystic ovary syndrome and endometrioid carcinoma (OR per log odds higher liability:0.74,95% CI:0.62-0.90;P=0.002). There was little evidence that genetic liability to type 2 diabetes, parity, or circulating levels of 25-hydroxyvitamin D and sex hormone-binding globulin were associated with ovarian cancer or its subtypes.\n\nConclusionsOur comprehensive examination of possible etiological drivers of ovarian carcinogenesis supports a causal role for few of these factors in epithelial ovarian cancer and suggests distinct etiologies across histotypes.

epidemiology↗

bioRxiv2018

scFTD-seq: freeze-thaw lysis based, portable approach toward high-quality distributed single-cell 3 mRNA profiling

Cellular barcoding of 3 mRNAs enabled massively parallel profiling of single-cell gene expression and has been implemented in droplet and microwell based platforms. The latter further adds the value for compatibility with low input samples, optical imaging, scalability, and portability. However, cell lysis in microwells remains suboptimal despite the recently developed sophisticated solutions. Here, we present scFTD-seq, a microchip platform for performing single-cell freeze-thaw lysis directly toward 3 mRNA sequencing. It offers format flexibility with a simplified, widely adoptable workflow that reduces the number of preparation steps and hands-on time, with the quality of data and the cost per sample matching that of the state-of-the-art scRNA-seq platforms. Freeze-thaw, known as an unfavorable lysis method resulting in possible RNA fragmentation, turns out to be fully compatible with single-cell 3 mRNA sequencing, which detects only ~50 bases at the 3 end. We applied it to the profiling of mixed populations including whole tumors for distinguishing all major cell types and to the profiling of circulating follicular helper T cells implicated in systemic lupus erythematosus pathogenesis. Our results delineate the heterogeneity in the transcriptional programs and effector functions of these rare pathogenic T cells. As scFTD-seq decouples on-chip cell isolation and the following library preparation steps, we envision it to potentially allow the sampling (capture of cells/beads in microwells) at the distributed sites including small clinics or point-of-care settings and downstream processing at a centralized facility, which should enable wide-spread adoption beyond academic laboratories - for any users even with no experience in scRNA-seq library generation.

bioengineering↗