Biology subjects

Li-Wai-Suen, C. S. N.

Publications and source records attributed to Li-Wai-Suen, C. S. N..

4 recordsLinked to original sources

bioRxiv2026

Regulation of Human Erythroferrone Expression

Erythroferrone (ERFE) is an erythroblast-secreted hormone that suppresses hepatic hepcidin expression to increase iron availability for erythropoiesis, ensuring recovery from anaemia. ERFE excess drives iron overload in disorders of ineffective erythropoiesis. Despite its pivotal role in systemic iron homeostasis and diseases of erythropoiesis, ERFEs molecular regulation has remained undefined. Here, we applied a genomic approach to characterise the molecular mechanisms governing ERFE expression. Using the HUDEP-2 human erythroid progenitor model, integrative ATAC-seq, CUT&RUN and micro capture-C analysis we identified a stage-specific accessible chromatin region within the ERFE 3 UTR that interacts with the promotor. We also identified enhancer-associated chromatin marks including H3K4me1 and H3K27ac in this region, and demonstrate that this cis-regulatory element is bound by key erythroid transcription factors KLF1, GATA1, TAL1 and STAT5. Functional dissection using CRISPR-Cas9-mediated deletion of the central 3 UTR enhancer element led to marked reduction in ERFE mRNA expression, and we show a corresponding reduction in nascent mRNA, confirming a key role for this region in transcriptional regulation. We define the transcriptional regulatory mechanism by which maturing human erythroblasts activate ERFE, the endocrine signal that coordinates erythropoietic demand with systemic iron mobilisation.

molecular biology↗

bioRxiv2024

Transcriptomic alterations including p53 pathway dysregulation prime DNMT3A mutant cells for transformation

DNMT3A mutations are prevalent in haematologic malignancies. Our mouse model introduced the murine homologue (R878H) of the human hotspot R882H mutation into the mouse Dnmt3a locus, resulting in globally reduced DNA methylation in all tissues. Mice with heterozygous R878H mutations developed {gamma}-radiation induced thymic lymphoma more rapidly than control mice, suggesting a vulnerability to stress stimuli in Dnmt3aR878H/+ cells. In competitive transplantations, Dnmt3aR878H/+ Lin-Sca-1+Kit+ (LSK) cells had a competitive advantage over wt cells, indicating a self-renewal phenotype at the expense of differentiation. RNA-sequencing of Dnmt3aR878H/+ LSKs exposed to low dose {gamma}-radiation showed downregulation of the p53 pathway. Accordingly, reduced PUMA expression was observed by flow cytometry in the bone marrow of {gamma}-irradiated Dnmt3aR878H/+ mice due to altered p53 signalling. These findings provide new insights as to how DNMT3A mutations cause subtle changes in the transcriptome of LSK cells which contribute to their increased self-renewal and propensity for malignant transformation. SIGNIFICANCEHotspot DNMT3A R882H mutations are overrepresented in leukaemia suggesting that they confer a susceptibility to disease if further mutations are acquired. To advance therapies for DNMT3A mutant disease, it is essential to understand the mechanisms by which this mutation primes cells for malignant transformation.

cancer biology↗

bioRxiv2022

Deletion of the transcriptional regulator TFAP4 accelerates c-MYC-driven lymphomagenesis

Many lymphoid malignancies arise from deregulated c-MYC expression in cooperation with additional genetic lesions. While many of these cooperative genetic lesions have been discovered, DNA sequence data suggest that many more do exist. However, their contributions to c-MYC driven lymphomagenesis have not yet been investigated. We identified TFAP4 as a potent suppressor of c-MYC driven lymphoma development in a previous genome-wide CRISPR knockout screen in primary cells in vivo (Mizutani et al, 2022). CRISPR deletion of TFAP4 in E-MYC transgenic hematopoietic stem and progenitor cells (HSPCs) significantly accelerated c-MYC-driven lymphoma development in mice. TFAP4 deficient E-MYC lymphomas all arose at the pre-B cell stage. Characterization of the transcriptional profile of pre-leukemic pre-B cells in E-MYC/Cas9/sgTFAP4 transplanted mice, revealed that TFAP4 deletion reduced expression of several master regulators of B cell differentiation, such as Spi1, SpiB and Pax5, which all have been shown to be bound by TFAP4. We therefore conclude that loss of TFAP4 leads to a block in differentiation during early B cell development, causing accelerated c-MYC-driven lymphoma development.

cancer biology↗

bioRxiv2018

Development and validation of serological markers for detecting recent exposure to Plasmodium vivax infection

In order to accelerate towards malaria elimination, improved targeting of limited resources is essential. A major gap in our elimination toolkit for Plasmodium vivax malaria is the identification of individuals carrying arrested liver stages, called hypnozoites. These clinically silent but frequently relapsing hypnozoites are key to P. vivax persistence. Whilst hypnozoites cannot be directly detected, individuals who have had recent exposure to P. vivax and have not been treated are likely to harbor these parasites. By measuring IgG antibody responses to over 300 P. vivax proteins, a panel of serological markers capable of detecting exposure to P. vivax infections in the prior 9-month period was identified and validated. Using antibody responses to 8 P. vivax proteins, 80% sensitivity and specificity for detecting recent infections were achieved in three independent studies conducted in Thailand, Brazil and the Solomon Islands. As these individuals have a high likelihood of harboring hypnozoites, the suite of these 8 antibody responses can serve as biomarkers for the identification of individuals who should be targeted for treatment with liver-stage drugs such as primaquine and tafenoquine in mass drug administration programs aimed at controlling and eliminating P. vivax malaria.\n\nOne Sentence SummaryThe manuscript describes identification and validation of a novel panel of P. vivax proteins that can be used to detect recent exposure to P. vivax infections within the prior 9 months.

microbiology↗