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result(s) for
"Lee, Suho"
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Transcription-dependent mobility of single genes and genome-wide motions in live human cells
2024
The human genome is highly dynamic across all scales. At the gene level, chromatin is persistently remodeled and rearranged during active processes such as transcription, replication and DNA repair. At the genome level, chromatin moves in micron-scale domains that break up and re-form over seconds, but the origin of these coherent motions is unknown. Here, we investigate the connection between genomic motions and gene-level activity. Simultaneous mapping of single-gene and genome-wide motions shows that the coupling of gene transcriptional activity to flows of the nearby genome is modulated by chromatin compaction. A motion correlation analysis suggests that a single active gene drives larger-scale motions in low-compaction regions, but high-compaction chromatin drives gene motion regardless of its activity state. By revealing unexpected connections among gene activity, spatial heterogeneities of chromatin and its emergent genome-wide motions, these findings uncover aspects of the genome’s spatiotemporal organization that directly impact gene regulation and expression.
The human genome is dynamic across all scales, from motions of single genes to the entire genome. Here, using live cell imaging, the authors study the connection between large-scale genomic motions and the transcriptional activity of single genes.
Journal Article
Kv7/KCNQ potassium channels in cortical hyperexcitability and juvenile seizure-related death in Ank2-mutant mice
2023
Autism spectrum disorders (ASD) represent neurodevelopmental disorders characterized by social deficits, repetitive behaviors, and various comorbidities, including epilepsy.
ANK2
, which encodes a neuronal scaffolding protein, is frequently mutated in ASD, but its in vivo functions and disease-related mechanisms are largely unknown. Here, we report that mice with
Ank2
knockout restricted to cortical and hippocampal excitatory neurons (Ank2-cKO mice) show ASD-related behavioral abnormalities and juvenile seizure-related death. Ank2-cKO cortical neurons show abnormally increased excitability and firing rate. These changes accompanied decreases in the total level and function of the Kv7.2/KCNQ2 and Kv7.3/KCNQ3 potassium channels and the density of these channels in the enlengthened axon initial segment. Importantly, the Kv7 agonist, retigabine, rescued neuronal excitability, juvenile seizure-related death, and hyperactivity in Ank2-cKO mice. These results suggest that Ank2 regulates neuronal excitability by regulating the length of and Kv7 density in the AIS and that Kv7 channelopathy is involved in Ank2-related brain dysfunctions.
Seizures can occur in autism spectrum disorders (ASD). Here, the authors report that mice lacking the ASD related Ank2 gene show abnormal behaviours, and juvenile seizure related death, through impaired Kv7 potassium channel function.
Journal Article
Ionic contrast across a lipid membrane for Debye length extension: towards an ultimate bioelectronic transducer
by
Taikjin Lee
,
Myung Chul Choi
,
Jae Hun Kim
in
631/1647/350/59
,
631/61/350/1057
,
639/925/350/59
2021
Despite technological advances in biomolecule detections, evaluation of molecular interactions via potentiometric devices under ion-enriched solutions has remained a long-standing problem. To avoid severe performance degradation of bioelectronics by ionic screening effects, we cover probe surfaces of field effect transistors with a single film of the supported lipid bilayer, and realize respectable potentiometric signals from receptor–ligand bindings irrespective of ionic strength of bulky solutions by placing an ion-free water layer underneath the supported lipid bilayer. High-energy X-ray reflectometry together with the circuit analysis and molecular dynamics simulation discovered biochemical findings that effective electrical signals dominantly originated from the sub-nanoscale conformational change of lipids in the course of receptor–ligand bindings. Beyond thorough analysis on the underlying mechanism at the molecular level, the proposed supported lipid bilayer-field effect transistor platform ensures the world-record level of sensitivity in molecular detection with excellent reproducibility regardless of molecular charges and environmental ionic conditions.
The design of bioelectronic devices that enables accurate detection of biomolecules in ionic solutions at physiologically-relevant concentrations remains a challenge. Here, the authors report a ion-impermeable supported lipid bilayer-assisted field-effect transistor platform for biomolecule detection.
Journal Article
Glycine-modulating Slc6a20a-ASO restores NMDA receptor function in SHANK2 and SHANK3-mutant mice and cortical organoids
2026
Suppressed NMDA receptor (NMDAR) function contributes to multiple brain disorders, including schizophrenia, autism spectrum disorder (ASD), and NMDAR encephalitis. Previous attempts to restore NMDAR activity by increasing ambient glycine, a critical co-agonist, through GlyT1 inhibition have yielded mixed outcomes, partly due to
GlyT1’s
extensive expression in essential brainstem regions. Slc6a20a, a glycine transporter widely expressed in cognition-relevant regions such as the cortex and hippocampus, offers a targeted alternative. Here we show that antisense oligonucleotide (ASO)-mediated
Slc6a20a
inhibition (
Slc6a20a
-ASO) normalizes ASD-related phenotypes in male
Shank2
- and
Shank3
-mutant mice, with model-dependent rescue profiles.
Slc6a20a
-ASO rescues NMDAR hypofunction and synaptic phospho-proteomic profiles in the prefrontal cortex. Furthermore, ASO targeting human
SLC6A20
rescues suppressed NMDAR function in cortical organoids harboring
SHANK2
or
SHANK3
mutations. These findings underscore the potential and limitations of
Slc6a20a
/
SLC6A20
-ASO for treating disorders characterized by NMDAR hypofunction.
Antisense oligonucleotides targeting the glycine transporter SLC6A20 restore NMDA -receptor function and rescue behavioral and synaptic phospho-proteomic deficits in Shank2- and Shank3-mutant mice and in human SHANK2/SHANK3 cortical organoids.
Journal Article
Integrative analysis of spatial and single-cell transcriptome data from human pancreatic cancer reveals an intermediate cancer cell population associated with poor prognosis
by
Lee, Hee Seung
,
Kim, Seongryong
,
Jo, Jung Hyun
in
Analysis
,
Applications of technology in health and disease
,
Bioinformatics
2024
Background
Recent studies using single-cell transcriptomic analysis have reported several distinct clusters of neoplastic epithelial cells and cancer-associated fibroblasts in the pancreatic cancer tumor microenvironment. However, their molecular characteristics and biological significance have not been clearly elucidated due to intra- and inter-tumoral heterogeneity.
Methods
We performed single-cell RNA sequencing using enriched non-immune cell populations from 17 pancreatic tumor tissues (16 pancreatic cancer and one high-grade dysplasia) and generated paired spatial transcriptomic data from seven patient samples.
Results
We identified five distinct functional subclusters of pancreatic cancer cells and six distinct cancer-associated fibroblast subclusters. We deeply profiled their characteristics, and we found that these subclusters successfully deconvoluted most of the features suggested in bulk transcriptome analysis of pancreatic cancer. Among those subclusters, we identified a novel cancer cell subcluster, Ep_VGLL1, showing intermediate characteristics between the extremities of basal-like and classical dichotomy, despite its prognostic value. Molecular features of Ep_VGLL1 suggest its transitional properties between basal-like and classical subtypes, which is supported by spatial transcriptomic data.
Conclusions
This integrative analysis not only provides a comprehensive landscape of pancreatic cancer and fibroblast population, but also suggests a novel insight to the dynamic states of pancreatic cancer cells and unveils potential therapeutic targets.
Graphical Abstract
Journal Article
Excitatory synapses and gap junctions cooperate to improve Pv neuronal burst firing and cortical social cognition in Shank2-mutant mice
2021
NMDA receptor (NMDAR) and GABA neuronal dysfunctions are observed in animal models of autism spectrum disorders, but how these dysfunctions impair social cognition and behavior remains unclear. We report here that NMDARs in cortical parvalbumin (Pv)-positive interneurons cooperate with gap junctions to promote high-frequency (>80 Hz) Pv neuronal burst firing and social cognition.
Shank2
–/–
mice, displaying improved sociability upon NMDAR activation, show impaired cortical social representation and inhibitory neuronal burst firing. Cortical
Shank2
–/–
Pv neurons show decreased NMDAR activity, which suppresses the cooperation between NMDARs and gap junctions (GJs) for normal burst firing.
Shank2
–/–
Pv neurons show compensatory increases in GJ activity that are not sufficient for social rescue. However, optogenetic boosting of Pv neuronal bursts, requiring GJs, rescues cortical social cognition in
Shank2
–/–
mice, similar to the NMDAR-dependent social rescue. Therefore, NMDARs and gap junctions cooperate to promote cortical Pv neuronal bursts and social cognition.
How NMDAR and GABA neuronal dysfunctions result in impaired social behaviour is unclear. Here, the authors show that NMDARs and gap junctions in cortical PV interneurons modulate burst firing, affecting social behaviour.
Journal Article
Alternatively spliced mini-exon B in PTPδ regulates excitatory synapses through cell-type-specific trans-synaptic PTPδ-IL1RAP interaction
2025
PTPδ, encoded by
PTPRD
, is implicated in various neurological, psychiatric, and neurodevelopmental disorders, but the underlying mechanisms remain unclear. PTPδ trans-synaptically interacts with multiple postsynaptic adhesion molecules, which involves its extracellular alternatively spliced mini-exons, meA and meB. While PTPδ-meA functions have been studied in vivo, PTPδ-meB has not been studied. Here, we report that, unlike homozygous PTPδ-meA-mutant mice, homozygous PTPδ-meB-mutant (
Ptprd-meB
–/–
) mice show markedly reduced early postnatal survival. Heterozygous
Ptprd-meB
+/–
male mice show behavioral abnormalities and decreased excitatory synaptic density and transmission in dentate gyrus granule cells (DG-GCs). Proteomic analyses identify decreased postsynaptic density levels of IL1RAP, a known trans-synaptic partner of meB-containing PTPδ. Accordingly, IL1RAP-mutant mice show decreased excitatory synaptic transmission in DG-GCs.
Ptprd-meB
+/–
DG interneurons with minimal IL1RAP expression show increased excitatory synaptic density and transmission. Therefore, PTPδ-meB is important for survival, synaptic, and behavioral phenotypes and regulates excitatory synapses in cell-type-specific and IL1RAP-dependent manners.
Synaptic adhesion molecules like PTPδ are critical for synapse formation and function. Here authors show PTPδ with mini-exon B regulates excitatory synapses in cell-type-specific and IL1RAP-dependent manners.
Journal Article
Inducing mitophagy in diabetic platelets protects against severe oxidative stress
by
Jin, Yu
,
Spollett, Geralyn
,
Tang, Wai Ho
in
Apoptosis
,
Autophagy
,
Blood Platelets - pathology
2016
Diabetes mellitus (DM) is a growing international concern. Considerable mortality and morbidity associated with diabetes mellitus arise predominantly from thrombotic cardiovascular events. Oxidative stress‐mediated mitochondrial damage contributes significantly to enhanced thrombosis in DM. A basal autophagy process has recently been described as playing an important role in normal platelet activation. We now report a substantial mitophagy induction (above basal autophagy levels) in diabetic platelets, suggesting alternative roles for autophagy in platelet pathology. Using a combination of molecular, biochemical, and imaging studies on human DM platelets, we report that platelet mitophagy induction serves as a platelet protective mechanism that responds to oxidative stress through JNK activation. By removing damaged mitochondria (mitophagy), phosphorylated p53 is reduced, preventing progression to apoptosis, and preserving platelet function. The absence of mitophagy in DM platelets results in failure to protect against oxidative stress, leading to increased thrombosis. Surprisingly, this removal of damaged mitochondria does not require contributions from transcription, as platelets lack a nucleus. The considerable energy and resources expended in “prepackaging” the complex mitophagy machinery in a short‐lived normal platelet support a critical role, in anticipation of exposure to oxidative stress.
Synopsis
Under conditions of the severe oxidative stress commonly associated with diabetes mellitus in patients, induction of platelet mitophagy protects the platelet from apoptosis by removing the damaged mitochondria and preserves platelets function.
Autophagy and mitophagy are increased in diabetic platelets.
Mitophagy is induced in platelets through an ROS/JNK‐mediated pathway.
Mitophagy induction serves to protect diabetic platelets from oxidative stress‐induced apoptosis.
Mitophagy induction protects against increased thrombosis associated with diabetes mellitus.
Graphical Abstract
Under conditions of the severe oxidative stress commonly associated with diabetes mellitus in patients, induction of platelet mitophagy protects the platelet from apoptosis by removing the damaged mitochondria and preserves platelets function.
Journal Article
Genome-wide methylation profiling reveals extracellular vesicle DNA as an ex vivo surrogate of cancer cell-derived DNA
2024
Extracellular vesicle-derived DNA (evDNA) encapsulates the complete genome and mutational status of cells; however, whether cancer cell-derived evDNA mirrors the epigenetic features of parental genomic DNA remains uncertain. This study aimed to assess and compare the DNA methylation patterns of evDNA from cancer cell lines and primary cancer tissues with those of the nuclear genomic DNA. We isolated evDNA secreted by two cancer cell lines (HCT116 and MDA-MB-231) from various subcellular compartments, including the nucleus and cytoplasm. Additionally, we obtained evDNA and nuclear DNA (nDNA) from the primary cancer tissues of colon cancer patients. We conducted a comprehensive genome-wide DNA methylation analysis using the Infinium Methylation EPIC BeadChip, examining > 850,000 CpG sites. Remarkable similarities were observed between evDNA and nDNA methylation patterns in cancer cell lines and patients. This concordance extended to clinical cancer tissue samples, showcasing the potential utility of evDNA methylation patterns in deducing cellular origin within heterogeneous populations through methylation-based deconvolution. The observed concordance underscores the potential of evDNA as a noninvasive surrogate marker for discerning tissue origin, particularly in cancer tissues, offering a promising future for cancer diagnostics. This finding enhances our understanding of cellular origins and would help develop innovative diagnostic and therapeutic strategies for cancer.
Journal Article
Non-coding de novo mutations in chromatin interactions are implicated in autism spectrum disorder
2022
Three-dimensional chromatin interactions regulate gene expressions. The significance of de novo mutations (DNMs) in chromatin interactions remains poorly understood for autism spectrum disorder (ASD). We generated 813 whole-genome sequences from 242 Korean simplex families to detect DNMs, and identified target genes which were putatively affected by non-coding DNMs in chromatin interactions. Non-coding DNMs in chromatin interactions were significantly involved in transcriptional dysregulations related to ASD risk. Correspondingly, target genes showed spatiotemporal expressions relevant to ASD in developing brains and enrichment in biological pathways implicated in ASD, such as histone modification. Regarding clinical features of ASD, non-coding DNMs in chromatin interactions particularly contributed to low intelligence quotient levels in ASD probands. We further validated our findings using two replication cohorts, Simons Simplex Collection (SSC) and MSSNG, and showed the consistent enrichment of non-coding DNM-disrupted chromatin interactions in ASD probands. Generating human induced pluripotent stem cells in two ASD families, we were able to demonstrate that non-coding DNMs in chromatin interactions alter the expression of target genes at the stage of early neural development. Taken together, our findings indicate that non-coding DNMs in ASD probands lead to early neurodevelopmental disruption implicated in ASD risk via chromatin interactions.
Journal Article