Biology subjects

Chu, W. K.

Publications and source records attributed to Chu, W. K..

4 recordsLinked to original sources

bioRxiv2026

Immunomodulatory Effects of Selenium on T-Cell-Mediated Responses in Thyroid Eye Disease

BackgroundThyroid Eye Disease (TED) is an autoimmune orbital disorder driven by pathogenic T-cell subsets, including T-helper 1 (Th1) and follicular helper T (Tfh) cells, which sustain orbital inflammation and thyroid-stimulating immunoglobulin (TSI) production. Selenium supplementation has demonstrated clinical benefit in mild TED, yet its immunological mechanisms remain poorly defined. MethodsA murine TED model was established in female BALB/c mice via TSHR plasmid immunisation. Animals maintained on a low-selenium diet (0.07 ppm) received sodium selenite supplementation at 0.2 mg/kg/day. Orbital pathology was assessed by immunohistochemistry, H&E and Massons Trichrome staining. T-cell subset abundance was quantified by flow cytometry, and serum T4, TRAb, and IL-21 levels were measured by ELISA. In vitro dose-response experiments examined the effects of selenium on Tfh cell viability, IL-21 production, apoptosis, and ferroptosis. ResultsSelenium supplementation reduced CD3 T-cell orbital infiltration, collagen fibrosis, and serum T4 and TRAb levels in TSHR-immunised mice. Flow cytometry revealed significant reductions in Tfh and Th1 cell abundance, with Th17 cells unaffected. Serum IL-21 and B-cell abundance were also markedly reduced in vivo. In vitro, selenium exhibited a biphasic, dose-dependent effect on Tfh cells: low concentrations maintained viability and IL-21 production, while higher concentrations induced ferroptosis and apoptosis. ConclusionsSelenium modulates pathogenic T-cell responses in TED, most prominently suppressing the Tfh compartment and attenuating the Tfh-B cell-autoantibody axis via ferroptosis and apoptosis. These findings suggest a mechanistic framework for the clinical benefit of selenium in mild TED and highlight the importance of dose selection within its narrow therapeutic window.

immunology↗

bioRxiv2023

The BOD1L subunit of the mammalian SETD1A complex sustains the expression of DNA damage repair genes despite restraining H3K4 trimethylation

SETD1A is the histone 3 lysine 4 (H3K4) methyltransferase central to the mammalian version of the highly conserved eight subunit Set1 complex (Set1C) that apparently conveys H3K4 trimethylation (H3K4me3) onto all active Pol II promoters. Accordingly, the Setd1a mouse knock-out dies in early embryogenesis at the epiblast stage and mouse embryonic stem cells (ESCs) die when SETD1A is removed. We report that ESC death is accompanied by loss of expression of DNA repair genes and accumulating DNA damage. BOD1L and BOD1 are homologs of the yeast Set1C subunit, Shg1, and subunits of the mammalian SETD1A and B complexes. We show that the Shg1 homology region binds to a highly conserved central alpha-helix in SETD1A and B. Like mutagenesis of Shg1 in yeast, conditional mutagenesis of Bod1l in ESCs promoted increased H3K4 di- and tri-methylation but also, like loss of SETD1A, loss of expression of DNA repair genes, increased DNA damage and cell death. In contrast to similar losses of DNA repair gene expression, the converse changes in H3K4 methylation after loss of SETD1A or BOD1L implies that H3K4 methylation is not essential for expression of the target DNA repair genes. Because BOD1L becomes highly phosphorylated after DNA damage and acts to protect damaged replication forks, the SETD1A complex, and BOD1L in particular, are key nodes for the DNA damage repair network.

cell biology↗

bioRxiv2019

Clinical investigation and genetic analysis of a peripheral sclerocornea pedigree

BackgroundSclerocomea is a rare congenital disorder characterized with cornea opacification. We identified a heterozygous missense RAD21 variant in a non-cons anguineous Chinese family with multiple peripheral sclerocomea patients spanning across three generations inherited in an autosomal dominant manner. MethodsComprehensive ophthalmic examinations were conducted on all 14 members. Whole exome sequencing was used to identify the genetic alterations in the affected pedigree members. Lymphoblastoid cell lines (LCLs) were established using blood samples from all members. Cleavage of RAD21 protein was quantified in these cell lines. ResultsAll affected individuals showed features of scleralization over the peripheral cornea of both eyes. Mean horizontal and vertical corneal diameter were significantly decreased in the affected members. Significant differences were also observed on mean apex pachymetry between affected and unaffected subjects. A RAD21C1348T variant was co-segregated with affected members. Both the wild-type allele and the missense variant were expressed at the mRNA level. This variant caused RAD21 R450C substitution at the separase cleavage site, which led to reduced RAD21 cleavage. ConclusionWe believe this is the first report of genetic variant in sclerocornea without other syndromes. Further work is needed to confirm the RAD21R450C variant with sclerocomea.

genetics↗

bioRxiv2017

Ultra-Accurate Genome Sequencing And Haplotyping Of Single Human Cells

Accurate detection of variants and long-range haplotypes in genomes of single human cells remains very challenging. Common approaches require extensive in vitro amplification of genomes of individual cells using DNA polymerases and high-throughput short-read DNA sequencing. These approaches have two notable drawbacks. First, polymerase replication errors could generate tens of thousands of false positive calls per genome. Second, relatively short sequence reads contain little to no haplotype information. Here we report a method, which is dubbed SISSOR (Single-Stranded Sequencing using micrOfluidic Reactors), for accurate single-cell genome sequencing and haplotyping. A microfluidic processor is used to separate the Watson and Crick strands of the double-stranded chromosomal DNA in a single cell and to randomly partition megabase-size DNA strands into multiple nanoliter compartments for amplification and construction of barcoded libraries for sequencing. The separation and partitioning of large single-stranded DNA fragments of the homologous chromosome pairs allows for the independent sequencing of each of the complementary and homologous strands. This enables the assembly of long haplotypes and reduction of sequence errors by using the redundant sequence information and haplotype-based error removal. We demonstrated the ability to sequence single-cell genomes with error rates as low as 10-8 and average 500kb long DNA fragments that can be assembled into haplotype contigs with N50 greater than 7Mb. The performance could be further improved with more uniform amplification and more accurate sequence alignment. The ability to obtain accurate genome sequences and haplotype information from single cells will enable applications of genome sequencing for diverse clinical needs.

genomics↗