Biology subjects

Lee, S. N.

Publications and source records attributed to Lee, S. N..

6 recordsLinked to original sources

bioRxiv2025

An atlas of natural killer cell receptor expression on healthy donor T and NK lymphocytes

Human T cells and natural killer (NK) cells exhibit variegated co-expression of germlineencoded receptors, which diversifies their effector functions. CD8+ T cell expression of receptors more typically associated with NK cells has been noted, but a systematic analysis of their distribution has not been described. Here, we comprehensively measured human NK cells and T cells expression of NK cell-associated receptors to define their co-expression and patterns associated with donor sex, maturation, and activation. To assess the activating and inhibitory receptor repertoire of human T cells and NK cells, we developed a 25-colour flow cytometry panel that included channels based on receptor functions. Since NK cell function is known to be driven by interactions with HLA supergroups (KIR ligands), we stratified donors based on KIR-HLA allelic combinations. NK and CD8+ T cell phenotypes and responsiveness were assessed at rest, and in response to the missing self target cell line, K562. We find that NK cells universally express CD45RA, CD161, and the inhibitory receptors TIGIT/TIM3/LAG3. On CD56dimCD16high NK cells (those most aligned with missing self reactivity, CD161, CD45RA, natural cytotoxicity receptors (NCRs), and TIGIT/TIM3/LAG3 were most frequently expressed. Not all educated NK cells respond to missing self-targets; those that did exhibited high expression of NCRs, NKG2C, IL-7R/IL-18Ra, and TIGIT/TIM3/LAG3, and lower expression of DNAM-1 and CCR7, in addition to the KIR molecules that defined their status as educated. We note that up to 50% of NK cells express CD8, and this population co-expressed CD16, NCRs, and KIR, and exhibited greater cytotoxicity than the CD8-NK cell population. Among CD8+ T cells, acquisition of NK cell-associated receptors was increased as they progressed through differentiation states: effector memory and terminally-differentiated CD8+ T cells exhibiting higher expression of NKG2A, KIR, and CD16. Taken together, the variability of receptor expression patterns highlights the diversity of lymphocyte populations and suggests shared features among the cytotoxic lymphocytes.

immunology↗

bioRxiv2024

Chromosome engineering to restore euploidy in cells harboring a complex rearrangement of chromosome 8

Chromosomal rearrangements on the short arm of Chromosome 8 cause 8p syndrome, a rare developmental disorder characterized by neurodevelopmental delays, epilepsy, and cardiac abnormalities. While significant progress has been made in managing the symptoms of 8p syndrome and other conditions caused by large-scale chromosomal aneuploidies, no therapeutic approach has yet been demonstrated to target the underlying disease-causing chromosome. Here, we establish a two-step approach to eliminate the abnormal copy of Chromosome 8 and restore euploidy in cells derived from an individual with a complex rearrangement of Chromosome 8p. Transcriptomic analysis revealed 361 differentially expressed genes between the proband and the euploid revertant, highlighting genes both within and outside the 8p region that may contribute to 8p syndrome pathology. Furthermore, we demonstrate that the proband exhibits a significant defect in neural differentiation that could be partially rescued by treatment with small-molecule inhibitors of cell death. Our work demonstrates the feasibility of using chromosome engineering to correct complex aneuploidies in vitro and establishes a platform to further dissect the pathophysiology of 8p syndrome and other conditions caused by chromosomal rearrangements.

developmental biology↗

bioRxiv2024

Rapid degradation of Histone Deacetylase 1 (HDAC1) reveals essential roles in both gene repression and active transcription

Histone Deacetylase 1 (HDAC1) removes acetyl groups from lysine residues on the core histones, a critical step in the regulation of chromatin accessibility. Despite histone deacetylation being an apparently repressive activity, suppression of HDACs causes both up- and down-regulation of gene expression. Here we exploited the degradation tag (dTAG) system to rapidly degrade HDAC1 in embryonic stem cells (ESCs) lacking its paralog, HDAC2. Unlike HDAC inhibitors that lack isoform specificity, the dTAG system allowed specific degradation and removal of HDAC1 in <1 hour (100x faster than genetic knockouts). This rapid degradation caused increased histone acetylation in as little as 2 hours, with H2BK5 and H2BK11 being the most sensitive. The majority of differentially expressed genes following 2 hours of HDAC1 degradation were upregulated (275 genes up vs 15 down) with increased proportions of downregulated genes observed at 6 (1,153 up vs 443 down) and 24 hours (1,146 up vs 967 down) respectively. Upregulated genes showed increased H2BK5ac and H3K27ac around their transcriptional start site (TSS). In contrast, decreased acetylation of super-enhancers (SEs) was linked to the most strongly downregulated genes. These findings suggest a paradoxical role for HDAC1 in the maintenance of histone acetylation levels at critical enhancer regions required for the pluripotency-associated gene network.

molecular biology↗

bioRxiv2024

Structure and dynamics of the autoantigen GAD65 in complex with the human autoimmune polyendocrine syndrome type 2-associated autoantibody b96.11

The enzyme glutamate decarboxylase (GAD) produces the neurotransmitter GABA, using pyridoxal-5-phosphate. GAD exists as two isoforms, GAD65 and GAD67. Only GAD65 acts as a major autoantigen, with its autoantibodies frequently found in type 1 diabetes and other autoimmune diseases. Here we characterize the structure and dynamics of GAD65 and its interaction with the autoimmune polyendocrine syndrome type 2-associated autoantibody b96.11. Combining hydrogen-deuterium exchange mass spectrometry (HDX), X-ray crystallography, cryo-electron microscopy and computational approaches, we dissect the conformational dynamics of the inactive apo- and the active holo-forms of GAD65, as well as the structure of the GAD65-autoantibody complex. HDX reveals the time-resolved, local dynamics that accompany autoinactivation, with the catalytic loop playing a key role in promoting collective dynamics at the interface between CTD and PLP domains. In the GAD65-b96.11 complex, heavy chain CDRs dominate the interaction, with the relatively long CDRH3 at the interface centre and uniquely bridging the GAD65 dimer via extensive electrostatic interactions with the 260PEVKEK265 motif. The autoantibody bridges structural elements on GAD65 that contribute to conformational change in GAD65, thus connecting the unique and intrinsic conformational flexibility that governs the autoinactivation mechanism of the enzyme to its autoantigenicity. The intrinsic dynamics, rather than sequence differences within epitopes, appear to be responsible for the contrasting autoantigenicities of GAD65 and GAD67. Our data thus reveal insights into the structural and dynamic differences between GAD65 and GAD67 that dictate their contrasting autoantibody reactivities, provide a new structural rationalisation for the nature of the autoimmune response to GAD65, and may have broader implications for antigenicity in general.

biochemistry↗

bioRxiv2023

A mouse model of ZTTK syndrome reveals indispensable SON functions in organ development and hematopoiesis

Rare diseases are underrepresented in biomedical research, leading to insufficient awareness. Zhu-Tokita-Takenouchi-Kim (ZTTK) syndrome is a rare disease caused by genetic alterations that result in heterozygous loss-of-function of SON. While ZTTK syndrome patients suffer from numerous symptoms, the lack of model organisms hamper our understanding of both SON and this complex syndrome. Here, we developed Son haploinsufficiency (Son+/-) mice as a model of ZTTK syndrome and identified the indispensable roles of Son in organ development and hematopoiesis. Son+/- mice recapitulated clinical symptoms of ZTTK syndrome, including growth retardation, cognitive impairment, skeletal abnormalities, and kidney agenesis. Furthermore, we identified hematopoietic abnormalities in Son+/- mice, similar to those observed in human patients. Surface marker analyses and single-cell transcriptome profiling of hematopoietic stem and progenitor cells revealed that Son haploinsufficiency inclines cell fate toward the myeloid lineage but compromises lymphoid lineage development by reducing key genes required for lymphoid and B cell lineage specification. Additionally, Son haploinsufficiency causes inappropriate activation of erythroid genes and impaired erythroid maturation. These findings highlight the importance of the full gene dosage of Son in organ development and hematopoiesis. Our model serves as an invaluable research tool for this rare disease and related disorders associated with SON dysfunction.

genetics↗

bioRxiv2023

Oncogene-like addiction to aneuploidy in human cancers

Most cancers exhibit aneuploidy, but its functional significance in tumor development is controversial. Here, we describe ReDACT (Restoring Disomy in Aneuploid cells using CRISPR Targeting), a set of chromosome engineering tools that allow us to eliminate specific aneuploidies from cancer genomes. Using ReDACT, we created a panel of isogenic cells that have or lack common aneuploidies, and we demonstrate that trisomy of chromosome 1q is required for malignant growth in cancers harboring this alteration. Mechanistically, gaining chromosome 1q increases the expression of MDM4 and suppresses TP53 signaling, and we show that TP53 mutations are mutually-exclusive with 1q aneuploidy in human cancers. Thus, specific aneuploidies play essential roles in tumorigenesis, raising the possibility that targeting these "aneuploidy addictions" could represent a novel approach for cancer treatment.

cancer biology↗