Biology subjects

Choi, E. S.

Publications and source records attributed to Choi, E. S..

4 recordsLinked to original sources

bioRxiv2025

Clonal dynamics of monozygotic twinning in early human embryogenesis

Monozygotic twins are derived from the split of a single zygote early in embryogenesis. Although it was hypothesized that the timing of twining is overall associated with fetal membrane configuration of twins, i.e., chorionicity and amnionicity, our understanding of early embryonic clonal dynamics underlying human twinning is limited. Here we explored the segregations of early embryonic lineages in 7 dichorionic diamniotic (DCDA), 7 monochorionic diamniotic (MCDA), 8 monochorionic monoamniotic (MCMA) monozygotic twins, and 1 dichorionic triamniotic (DCTA) monozygotic triplets, using post-zygotic early embryonic mutations (EEMs) as endogenous lineage barcodes. Patterns of the early lineage distributions among monozygotic twins revealed three apparent clonal categories, referred to as para-identical, sub-identical, and full-identical twins, which largely correlated with the amnionicity of the twins. Rather, despite conventional wisdom, chorionicity was not substantially associated with early clonal compositions, but with blood exchanges in utero. In sub-identical twins, where one co-twin was clonally a part of the other, our data suggested that the foundation of the latter co-twin was established after acquisition of a median of 6 additional post-zygotic mutations (range: 2-13), corresponding to [~]5 early cell divisions. Additional in-depth analysis on the matched placenta from an MCDA twin suggested that separation of two co-twins can precede the separation of the placenta and embryonic proper, and a single chorion can be formed even with multiclonal origin. Our findings provide insights into the clonal dynamics, twinning processes, and cell fate decisions in early human embryogenesis.

genomics↗

bioRxiv2024

Unveiling the double-edged sword: SOD1 trimers possess tissue-selective toxicity and bind septin-7 in motor neuron-like cells

Misfolded soluble trimeric species of superoxide dismutase 1 (SOD1) are associated with increased death in neuron-like cell models and greater disease severity in amyotrophic lateral sclerosis (ALS) patients compared to insoluble protein aggregates. The mechanism by which structurally independent SOD1 trimers cause cellular toxicity is unknown but may be a driver of disease pathology. Here, we uncovered the SOD1 trimer interactome - a map of potential tissue-selective protein binding partners in the brain, spinal cord, and skeletal muscle. We identified binding partners and key pathways associated with SOD1 trimers, comparing them to those of wild-type SOD1 dimers. We found that trimers may affect normal cellular functions such as dendritic spine morphogenesis and synaptic function in the central nervous system and cellular metabolism in skeletal muscle. We also identified key pathways using transcriptomic data from motor neuron-like cells (NSC-34s) expressing SOD1 trimers. We discovered differential gene expression in cells that express SOD1 trimers with selective enrichment of genes responsible for protein localization to membranes and a global upregulation of cellular senescence pathways. We performed detailed computational and biochemical characterization of protein binding for septin-7, an SOD1 trimer binding partner. We found that septin-7 preferentially binds SOD1 trimers and co-localizes in neuron-like cells. We explore a double-edged sword theory regarding the toxicity of SOD1 trimers. These trimers are implicated in causing dysfunction not only in the central nervous system but also in muscle tissues. Our investigation highlights key protein factors and pathways within each system, revealing a plausible intersection of genetic and pathophysiological mechanisms in ALS through interactions involving SOD1 trimers. SummaryIn amyotrophic lateral sclerosis (ALS), misfolded soluble species of superoxide dismutase 1 (SOD1) are associated with disease severity and, specifically, trimeric forms of SOD1 are toxic in neuron-like cells compared to insoluble aggregates. The role of toxic SOD1 trimers in cells is unknown. Using molecular engineering and pull-down experiments, we found that SOD1 trimers have tissue-selective protein interactions that affect pathways such as dendritic spine morphogenesis and synaptic function in the nerves, energy, and amino acid metabolism in skeletal muscle. We investigated the SOD1 trimer transcriptome to reveal a global upregulation of genes associated with cellular senescence compared to SOD1 dimers. We further validated septin-7, a shared brain and spinal cord protein binding hit, using integrative computational and biochemical approaches, and confirmed that septin-7 binds SOD1 trimers and not native dimers. Taken together, we show evidence that SOD1 trimers play a central role in the convergence of ALS pathophysiology. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/586186v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@35e9d9org.highwire.dtl.DTLVardef@18bbc3corg.highwire.dtl.DTLVardef@f30b02org.highwire.dtl.DTLVardef@57e51b_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

RNF213 variant and autophagic impairment: A pivotal link to endothelial dysfunction in Moyamoya disease

BackgroundMoyamoya disease (MMD) is closely associated with the Ring Finger Protein 213 (RNF213), a susceptibility gene for this disease. However, its biological function remains unclear. We aimed to elucidate the role of RNF213 in the damage incurred by human endothelial cells under oxygen-glucose deprivation (OGD), a condition that mimics intracranial ischemia in patients with MMD. MethodsWe analyzed autophagy in peripheral blood mononuclear cells (PBMCs) derived from patients carrying either RNF213 wild-type (WT) or variant (R4810K). Subsequently, human umbilical vein endothelial cells (HUVECs) were transfected with RNF213 WT (HUVECWT) or R4810K (HUVECR4810K) and exposed to OGD for 2 h to determine the role of the RNF213 variant in such a setting. Immunoblotting was used to analyze autophagy marker proteins, and tube formation assays were performed to examine endothelial function. Autophagic vesicles were observed using transmission electron microscopy. Post-OGD exposure, we administered autophagy modulators such as rapamycin and cilostazol. ResultsThe RNF213 variant group during post-OGD exposure (vs. pre-OGD exposure) showed autophagy inhibition, increased protein expression of SQSTM1/p62 (p < 0.0001) and LC3-II (p = 0.0039), and impaired endothelial function (p = 0.0252). HUVECR4810K during post-OGD exposure (versus pre-OGD exposure) showed a remarkable increase in autophagic vesicles. Administration of autophagy modulators notably restored the function of HUVECR4810K and cellular autophagy. ConclusionsOur findings support the pivotal role of autophagy impaired by the RNF213 variant in MMD-induced endothelial cell dysfunction and underscore the critical mechanism of autophagy leading to progressive endothelial dysfunction and MMD pathogenesis under relative ischemia within the intracranial portion.

neuroscience↗

bioRxiv2019

Cardiac myocytes respond differentially and synergistically to matrix stiffness and topography

During cardiac disease progression, myocytes undergo molecular, functional and structural changes, including increases in cell size and shape, decreased myocyte alignment and contractility. The heart often increases extracellular matrix production and stiffness, which affect myocytes. The order and hierarchy of these events remain unclear as available in vitro cell culture systems do not adequately model both physiologic and pathologic environments. Traditional cell culture substrates are 5-6 orders of magnitude stiffer than even diseased native cardiac tissue. Studies that do account for substrate stiffness often do not consider intercellular alignment and vice versa. We developed a cardiac myocyte culture platform that better recapitulates native tissue stiffness while simultaneously introducing topographical cues that promote cellular alignment. We show that stiffness and topography impact myocyte molecular and functional properties. We used a spatiotemporally-tunable, photolabile hydrogel platform to generate a range of stiffness and micron-scale topographical patterns to guide neonatal rat ventricular myocyte morphology. Importantly, these substrate patterns were of subcellular dimensions to test whether cells would spontaneously respond to topographical cues rather than an imposed geometry. Cellular contractility was highest and the gene expression profile was most physiologic on gels with healthy cardiac tissue stiffness. Surprisingly, while elongated patterns in stiff gels yielded the greatest cellular alignment, the cells actually had more pathologic functional and molecular profiles. These results highlight that morphological measurements alone are not a surrogate for overall cellular health as many studies assume. In general, substrate stiffness and micropatterning synergistically affect cardiac myocyte phenotype to recreate physiologic and pathologic microenvironments.\n\nSignificance StatementHeart disease is accompanied by organ- and cellular-level remodeling, and deconvoluting their interplay is complex. Cellular-level change is best studied in vitro due to greater control and uniformity of cell types compared to animals. One common metric is degree of cellular alignment as misalignment of myocytes is a hallmark of disease. However, most studies utilize featureless culture surfaces that are orders of magnitude stiffer than, and do not mimic the scaffolding of, the heart. We developed a hydrogel platform with tunable stiffness and patterns providing topographical alignment cues. We cultured heart cells on and characterized multifactorial responses to these dynamic surfaces. Interestingly, conditions that yielded greatest alignment did not yield the healthiest functional and molecular state. Thus, morphology alone is not an indicator of overall cellular health.

cell biology↗