Biology subjects

Hsu, K.

Publications and source records attributed to Hsu, K..

7 recordsLinked to original sources

bioRxiv2025

Stereoselective Degradation of Diacylglycerol Kinases Potentiate T cell Activation and Tumor Cell Cytotoxicity

Stereoselective recognition is a powerful means to differentiate selective versus non-specific activity of small molecules in complex biological systems. Here, we disclose stereochemically defined, sulfonyl-triazole inhibitors of the lipid enzyme diacylglycerol kinase-alpha (DGK), a key metabolic checkpoint for T cell effector function. Acute treatment with the covalent DGK inhibitor AHL-7160 recruited endogenous DGK to the plasma membrane in a stereoselective and isozyme-specific manner. The membrane translocation activity of AHL-7160 correlated with blockade of cellular phosphatidic acid production and potentiation of primary T cell-mediated killing of a glioblastoma cell line. Quantitative chemoproteomics revealed Y669 and K411 as sites of AHL-7160 modification on endogenous DGK in cells. Extended treatments resulted in proteasome-dependent and proteome-wide selective degradation of DGK in T cells. Collectively, these findings establish covalent DGK ligands as potent molecular glues with translational potential in immunotherapy.

biochemistry↗

bioRxiv2025

Impaired subgranular zone radial glia morphology and transient amplification of neural progenitors in Mllt11-deficient mice leads to increased hippocampal neurogenesis

The mammalian hippocampus derives from the cortical hem region of the forebrain and is one of the two regions in the mammalian forebrain that contains neural progenitors capable of generating new neurons in the postnatal brain. Hippocampal neural stem cells, referred to as type I progenitors, are Sox2+/GFAP+, localize along the hilar boundary region, and possess a radial glia fiber that spans the thickness of the dentate gurus. The hilar boundary region serves as a niche for the neural progenitor pool, controlling the activation of type-1 progenitors to transit amplifying type-2 neural progenitors which lose their apical adherence to the hilus as they differentiate to granule cells. The genetic regulation of this process is not fully understood and requires factors that control the mobilization of type-1 cells from their hilar niche in the subgranular zone. To that end we now report a role for Mllt11 (Af1q/Tcf7c; Myeloid/lymphoid or mixed-lineage leukemia; translocated to chromosome 11/All1 Fused Gene from Chromosome 1q/T cell factor 7 co-factor), a regulator of neurite formation and migration in the cortex, in the regulation of hippocampal neurogenesis by restricting the transition of type-1 cells to transit amplifiers and neuroblasts. We previously showed that Cux2 (Cutl2) is widely expressed in the developing hippocampus, initially in the subventricular zone of the cortical hem, which generates the dentate gyrus, then in both type-1 and type-2 neural progenitors, and later in maturing granule cells of the perinatal hippocampus. To evaluate a role for Mllt11 in hippocampal neurogenesis, we used a Cux2IRESCre/+ line to generate a Mllt11 loss-of-function in perinatal hippocampal progenitors and differentiating granule cells. The loss of Mllt11 led to enlarged dentate blades dues to increased generation of NeuN+ and Calbindin+ granule cells. Explorations of the progenitor pool revealed increased transit amplifying cells due to an expanded pool of displaced Sox2+/GFAP+ deep in the dentate blades, with altered radial glial morphology. Consequently, type-1 progenitors aberrantly transitioned to amplifying progenitors and neuroblasts, resulting in enhanced granule cell neurogenesis in the postnatal hippocampus. Primary neurosphere formation assays confirmed enhanced proliferation of neural stem cells derived from Mllt11 knockout hippocampi. Taken together, the findings reported here demonstrate the critical role of Mllt11 in maintaining the hippocampal radial glial phenotype and their association within the subgranular zone-hilar niche boundary region, thereby controlling their differentiation to transit amplifiers and granule cells.

developmental biology↗

bioRxiv2024

Loss of circulating CD8α+ NK cells during human Mycobacterium tuberculosis infection

Natural Killer (NK) cells can recognize and kill Mtb-infected cells in vitro, however their role after natural human exposure has not been well-studied. To identify Mtb-responsive NK cell populations, we analyzed the peripheral blood of healthy household contacts of active Tuberculosis (TB) cases and source community donors in an endemic region of Port-au-Prince, Haiti by flow cytometry. We observed higher CD8 expression on NK cells in putative resistors (IGRA-contacts) with a progressive loss of these circulating cells during household-associated latent infection and disease. In vitro assays and CITE-seq analysis of CD8+ NK cells demonstrated enhanced maturity, cytotoxic gene expression, and response to cytokine stimulation relative to CD8- NK cells. CD8+ NK cells also displayed dynamic surface expression dependent on MHC I in contrast to conventional CD8+ T cells. Together, these results support a specialized role for CD8+ NK cell populations during Mtb infection correlating with disease resistance.

immunology↗

bioRxiv2023

Widespread sex-dimorphism across single-cell transcriptomes of adult African turquoise killifish tissues

The African turquoise killifish (Nothobranchius furzeri), the shortest-lived vertebrate that can be bred in captivity, is an emerging model organism to study vertebrate aging. Here we describe the first multi-tissue, single-cell gene expression atlas of female and male turquoise killifish tissues comprising immune and metabolic cells from the blood, kidney, liver, and spleen. We were able to annotate 22 distinct cell types, define associated marker genes, and infer differentiation trajectories. Using this dataset, we found pervasive sex-dimorphic gene expression across cell types, especially in the liver. Sex-dimorphic genes tended to be involved in processes related to lipid metabolism, and indeed, we observed clear differences in lipid storage in female vs. male turquoise killifish livers. Importantly, we use machine-learning to predict sex using single-cell gene expression in our atlas and identify potential transcriptional markers for molecular sex identity in this species. As proof-of-principle, we show that our atlas can be used to deconvolute existing liver bulk RNA-seq data in this species to obtain accurate estimates of cell type proportions across biological conditions. We believe that this single-cell atlas can be a resource to the community that could notably be leveraged to identify cell type-specific genes for cell type-specific expression in transgenic animals.

genomics↗

bioRxiv2021

Mllt11 regulates the migration and neurite outgrowth of cortical projection neurons during development

The formation of connections within the mammalian neocortex is highly regulated by both extracellular guidance mechanisms and intrinsic gene expression programs. There are generally two types of cortical projection neurons: those that project locally and interhemispherically, and those that project to sub-cerebral structures such as the thalamus, hindbrain, and spinal cord. The regulation of cortical projection morphologies is not yet fully understood at the molecular level. Here we report a role for Mllt11 (Myeloid/lymphoid or mixed-lineage leukemia; translocated to chromosome 11/All1 Fused Gene From Chromosome 1q) in the migration and neurite outgrowth of callosal projection neurons during brain formation. We show that Mllt11 expression is exclusive to developing neurons and is enriched in the developing cortical plate, particularly during the formation of the upper or superficial cortical layers. In cultured primary cortical neurons, Mllt11 is detected in varicosities and growth cones as well as the soma. Using conditional loss-of-function and gain-of-function analysis we show that Mllt11 is a required for neuritogenesis and proper migration of upper layer cortical projection neurons. Loss of Mllt11 in the superficial cortex leads to a severe reduction in fibres crossing the corpus callosum, a progressive loss in the maintenance of upper layer projection neuron gene expression, and dysplasia of dendritic arborisation patterns. Proteomic analysis revealed that Mllt11 associates with cytoskeletal components including stabilized microtubules consistent with a role in neuronal migration and neuritogenesis. Taken together, our findings support a role for Mllt11 in promoting the formation of mature projection neuron morphologies and connectivity in the cerebral cortex.

developmental biology↗

bioRxiv2018

Recombinant expression of Proteorhodopsin and biofilm regulators in Escherichia coli for nanoparticle binding and removal in a wastewater treatment model

The small size of nanoparticles is both an advantage and a problem. Their high surface-area-to-volume ratio enables novel medical, industrial, and commercial applications. However, their small size also allows them to evade conventional filtration during water treatment, posing health risks to humans, plants, and aquatic life. This project aims to remove nanoparticles during wastewater treatment using genetically modified Escherichia coli in two ways: 1) binding citrate-capped nanoparticles with the membrane protein Proteorhodopsin, and 2) trapping nanoparticles using Escherichia coli biofilm produced by overexpressing two regulators: OmpR234 and CsgD. We demonstrate experimentally that Escherichia coli expressing Proteorhodopsin binds to 60 nm citrate-capped silver nanoparticles. We also successfully upregulate biofilm production and show that Escherichia coli biofilms are able to trap 30 nm gold particles. Finally, both Proteorhodopsin and biofilm approaches are able to bind and remove nanoparticles in simulated wastewater treatment tanks. We envision integrating our trapping system in both rural and urban wastewater treatment plants to efficiently capture all nanoparticles before treated water is released into the environment.\n\nFinancial DisclosureThis work was funded by the Taipei American School. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.\n\nCompeting InterestsThe authors have declared that no competing interests exist.\n\nEthics StatementN/A\n\nData AvailabilityYes - all data are fully available without restriction. Sequences for the plasmids used in this study are available through the Registry of Standard Biological Parts. Links to raw data are included in Supplementary Information.

synthetic biology↗

bioRxiv2017

Impact of rapid susceptibility testing and antibiotic selection strategy on the emergence and spread of antibiotic resistance in gonorrhea

BackgroundIncreasing antibiotic resistance limits treatment options for gonorrhea. We examined the extent to which a hypothetical point-of-care (POC) test reporting antibiotic susceptibility profiles could slow the spread of resistance.\n\nMethodsWe developed a deterministic compartmental model describing gonorrhea transmission in a single-sex population with three antibiotics available to treat infections. Probabilities of resistance emergence on treatment and fitness costs associated with resistance were based on characteristics of ciprofloxacin, azithromycin, and ceftriaxone. We evaluated time to 1% and 5% prevalence of resistant strains among all isolates with: (1) empiric treatment (azithromycin plus ceftriaxone), and treatment guided by POC tests determining susceptibility to (2) ciprofloxacin only and (3) all three antibiotics.\n\nFindingsBased on current gonococcal susceptibility patterns in the United States, the model indicated that continued empiric dual antibiotic treatment without POC testing resulted in >5% of isolates being resistant to both azithromycin and ceftriaxone within 15 years. When either POC test was used in 10% of identified cases, this was delayed by 5 years. The three antibiotic POC test delayed the time to reach 1% prevalence of triply-resistant strains by 6 years, while the ciprofloxacin-only test resulted in no delay. Results were less sensitive to assumptions about fitness costs and test characteristics with increasing test uptake. The main limitation of this study is that we made simplifying assumptions to describe gonorrhea transmission and the emergence and spread of resistance in the population.\n\nConclusionsRapid diagnostics that report antibiotic susceptibility have the potential to extend the usefulness of existing antibiotics for treatment of gonorrhea. Monitoring resistance patterns will be critical with the introduction of such tests.

epidemiology↗