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Lipid regulation is crucial role in Alzheimer's disease (AD) pathogenesis. In AD,microglia show elevated sterol O‐acyltransferase 1/Acyl‐coenzymeA: Choleseterol Acyltransferase 1 (SOAT1) expression,encoding Acyl‐coenzymeA: Cholesterol Acyltransferase 1  (ACAT1),which produces cholesteryl esters (CEs) in lipid droplets. Inhibiting ACAT1 has been shown to reduce amyloid beta (Aβ) pathology,though the mechanism is unclear. Methods: We inhibited ACAT1 using avasimibe (AV) in wild‐type,triggering receptor expressed on myeloid cells 2 (TREM2) knockout (KO),and low‐density lipoprotein receptor related protein 1 (LRP1) KO mouse BV2 and human induced pluripotent stem cell‐derived microglia and measured the impact on Aβ uptake to determine the mechanism through which the inhibition of ACAT1 enhances Aβ uptake. Results: ACAT1 inhibition increased LRP1 levels and soluble TREM2 (sTREM2) release via enhanced TREM2 cleavage by ADAM metallopeptidase domain 10/17 (ADAM10/17). KO of TREM2 or blockade of sTREM2 release prevented AV‐enhanced Aβ uptake. This effect was rescued by recombinant sTREM2,but only when LRP1 was present. Discussion: ACAT1 inhibition promotes microglial Aβ uptake in a sTREM2‐ and LRP1‐dependent manner,offering insights into novel therapeutic strategies for AD. Highlights: Inhibition of ACAT1,the major enzyme that catalyzes cholesterol storage via esterification enhances microglia‐mediated Aβ uptake. Increased Aβ uptake is dependent on the presence of both TREM2 and LRP1. Inhibition of ACAT1 increases cleavage of TREM2 via ADAM10/17 to release sTREM2. Treatment of microglial cells with sTREM2 rescues Aβ uptake in TREM2 KO BV2 cells.Inhibition of ACAT1 promotes Aβ uptake through increased shedding of TREM2,which enhances Aβ uptake through a LRP1‐dependent mechanism. View Publication

Circulating tumor cell (CTC) detection in hepatocellular carcinoma (HCC) is limited not only by the rarity of CTCs but also by a heavy reliance on cell surface markers such as EpCAM,which are variably expressed or lost during tumor progression. Detecting intracellular markers,such as cytokeratin offers an important complementary and comprehensive strategy but remains technically limited in flow cytometry due to the need for fixation and permeabilization,which often lead to cell loss and surface epitope damage. In this study,we systematically evaluated the feasibility of using fixed samples for flow cytometry,using HepG2 cells,PBMCs,and CTCs from patients with HCC. Our results demonstrate that fixation enabled intracellular staining without compromising cell surface marker detection,even after short-term storage at 4 °C and long-term storage at -80 °C. Fixed samples,particularly fixed unfrozen,exhibited comparable staining performance to fresh samples with only a 7–10% reduction in cell recovery. Clinical validation in HCC patients confirmed successful CTC detection,and tumor-specific CTNNB1 mutations were identified in CTC-derived DNA but not in matched plasma cfDNA. These findings support fixed CTC sample workflows as a reliable and practical approach for CTC analysis in HCC. View Publication

The maintenance of a basal immunoinflammatory signature in hematopoietic stem/progenitor cells (HSPCs) constitutes a fundamental regulatory axis governing hematopoietic competence and immune effector generation. While epigenetic repressors constrain this inflammatory phenotype,the molecular amplifiers that preserve this critical state remain undefined. Through integrated single-cell transcriptomic/epigenomic profiling and functional interrogation,we identify Setd2-mediated H3K36me3 as an indispensable epigenetic amplifier sustaining baseline inflammation in murine HSPCs. Setd2 ablation specifically eliminated interferon (IFN)-enriched HSPC subpopulations and attenuated inflammatory signaling cascades. Functionally,Setd2-deficient HSPCs exhibited impaired IFNγ responsiveness,compromised B-lymphopoiesis,and diminished reconstitution capacity due to Lin−c-Kit+Sca1high cell depletion. Paradoxically,Setd2 loss conferred resistance to IFNγ-induced HSPCs exhaustion,which may contribute to the maintenance of Setd2-deficient HSPCs in our myelodysplastic syndrome (MDS) model under the inflammatory milieu. Mechanistically,Setd2 sustained chromatin accessibility and enhancer (H3K27ac) activity at inflammatory gene loci. This work delineates a critical link between Setd2-mediated chromatin regulation,baseline inflammation,HSPC function,and immune competence,providing insights into inflammatory dysregulation in hematopoietic malignancies like MDS. View Publication

In the arms race between a pathogen and the host,the defense mechanisms of the host cell,including the ubiquitin system,are often counteracted by bacteria. Simkania negevensis (Sne),an obligate intracellular Chlamydia-like bacterium connected with respiratory diseases,possesses numerous deubiquitinases,but not much is known about its other ubiquitin-modifying enzymes. Sne infects a wide range of hosts,developing inside a tubular vacuole in close contact with the host endoplasmic reticulum (ER) and mitochondria. Our study describes an uncharacterized Sne ubiquitin E3 RING-ligase (SNE_A12920 or SneRING),which primarily generates K63- and K11-linked ubiquitin chains and preferentially interacts with UbcH5b and UBE2T E2 enzymes. SneRING is expressed upon infection of various human cell lines,as well as amoebae. We show that a portion of the expressed SneRING co-localizes with mitochondria and ER and that the SneRING interactome includes mitochondrial and ER proteins involved in organelle morphology and stress response. Our work offers an initial characterization of a bacterial RING ligase potentially involved in the host cell remodeling to accommodate the unique intracellular lifestyle of Sne. Author summaryUbiquitination is a protein modification system that regulates protein degradation,localization,or interactions. As such,ubiquitination has many important functions in cell signalling,and its dysregulation can lead to cancer and neurodegenerative diseases. Bacteria that live and develop inside human or other eukaryotic cells,such as Chlamydia,often modulate the ubiquitination system to ensure their own survival. Simkania negevensis is a Chlamydia-like bacterium connected to respiratory diseases in humans. We have discovered a novel enzyme expressed by these bacteria that can ubiquitinate other proteins and thus potentially modify host cell processes that would otherwise hinder infection. In this work,we explore the function of this enzyme and determine its possible cellular localization,as well as some of the proteins it interacts with. Our study provides new insights into how bacterial pathogens adapt to and manipulate host cells using one of the major cell function regulatory systems. View Publication

Antibody–drug conjugates (ADCs) represent a promising strategy in cancer therapy,enabling the targeted delivery of cytotoxic agents to tumor cells. In this study,we developed and characterized novel ADCs combining the anti-EGFR monoclonal therapeutic antibody Cetuximab (Cet) with two aminobisphosphonates (N-BPs) analogues of zoledronic acid (ZA): DC310 and the aminothiazole DC315. These conjugates aim to enhance antitumor efficacy of Cet in colorectal cancer (CRC) by both directly inhibiting tumor cell growth and activating Vδ2 T lymphocytes. We optimized the drug-antibody ratio (DAR),achieving significantly higher DARs compared to previously reported Cet-ZA conjugate,particularly with Cet-DC315 (DAR ≈ 23). Both ADCs retained selective EGFR binding in CRC cell lines and patient-derived organoids (PDO). Functionally,Cet-DC315 markedly inhibited proliferation of EGFR⁺ CRC cell lines in conventional cultures and 3D spheroids. Furthermore,Cet-DC-315 uniquely induced expansion and cytotoxic activation of Vδ2 T cells in co-cultures with CRC cell lines,PDO,and primary tumor samples. These findings suggest that ADCs incorporating novel N-BPs such as DC315 represent a potent approach for dual antitumor targeting through direct cytostatic effects and immune activation,offering a potential therapeutic advantage in the treatment of EGFR+ colorectal cancer. View Publication

Parechovirus ahumpari 3 (HPeV-3) is among the main agents causing severe neonatal neurological infections such as encephalitis and meningitis. However,the underlying molecular mechanisms and changes to the host cellular landscape leading to neurological disease has been understudied. Through quantitative proteomic analysis of HPeV-3 infected neural organoids,we identified unique metabolic changes following HPeV-3 infection that indicate immunometabolic dysregulation. Protein and pathway analyses showed significant alterations in neurotransmission and potentially,neuronal excitotoxicity. Elevated levels of extracellular glutamate,lactate dehydrogenase (LDH),and neurofilament light (NfL) confirmed glutamate excitotoxicity to be a key mechanism contributing to neuronal toxicity in HPeV-3 infection and can lead to apoptosis induced by caspase signaling. These insights are pivotal in delineating the metabolic landscape following severe HPeV-3 CNS infection and may identify potential host targets for therapeutic interventions. View Publication

Regulatory T cells are a class of T lymphocytes which respond to activation signals by expanding their cell numbers,and whose culturing and expansion are of significant clinical interest. Cellular activation states are used to inform process control decisions such as restimulation and can be probed with experimental measurements of cell surface markers. However,these measurements are expensive,time-consuming,and invasive,and an urgent need exists for devising a non-invasive method for activation state monitoring that could be deployed on-line. Raman spectroscopy is a label-free and information-rich optical method that,when coupled to data analytical methods,can ameliorate these experimental issues. In this work,we quantitatively estimated experimental measurements of regulatory T cell activation markers with high accuracy. We simulated a clinical manufacturing setting by building an L1-regularized least-squares model with spectroscopic data from six regulatory T cell donors. Then,we validated the constructed model by accurately estimating different experimental measurements of biomarker values from two external donors,unseen by the model. We have devised a robust program to effectively estimate the activation state of regulatory T cells. We anticipate our method to be used with on-line Raman probes integrated into cell manufacturing devices for label-free monitoring of these processes. View Publication

USH2A mutations are the leading cause of autosomal recessive retinitis pigmentosa (RP),a progressive blinding disease marked by photoreceptor degeneration. Animal models fail to recapitulate the features of USH2A RP seen in humans,and its earliest pathogenic events remain unknown. Here,we established a human model of USH2A RP using retinal organoids derived from patient induced pluripotent stem cells and CRISPR-Cas9-engineered isogenic-USH2A−/− induced pluripotent stem cells. Methods: We assessed organoids for cellular,molecular,and morphological defects using serial live imaging and whole organoid and fixed section analyses. Results: Both patient-derived and isogenic-USH2A−/− organoids showed preferential rod photoreceptor loss followed by widespread degeneration,consistent with the clinical phenotype. Additionally,isogenic-USH2A−/− organoids showed early defects in proliferation and structure. Conclusions: Our findings suggest that molecular changes precede overt photoreceptor loss in USH2A RP,and pathogenesis may begin before clinical symptoms emerge. By defining early and late disease features,we provide new insight on the developmental origins of USH2A RP to guide therapeutic strategies. View Publication

The selective peroxisome proliferator–activated receptor delta (PPARD) agonist seladelpar reduces liver injury and modulates bile acid metabolism in preclinical models. Seladelpar was recently approved for the secondary treatment of primary biliary cholangitis (PBC). Despite its beneficial effects for liver diseases,the target cells of seladelpar on a single-cell level remain unknown. This study is aimed at investigating the effect of seladelpar on single liver cells. Methods and Results: CD-1 mice were gavaged with vehicle or seladelpar (10 mg/kg body weight),and the liver was harvested 6 h later. Single-nuclei RNA sequencing (snRNA-seq) analysis showed the engagement of PPARD target genes primarily in hepatocytes and cholangiocytes by seladelpar. The top two upregulated genes,Ehhadh and Cyp4a14,are related to fatty acid metabolism and were increased in hepatocytes,cholangiocytes,and Kupffer cells. Abcb4,an important canalicular transporter with hepatoprotective effects,was significantly upregulated in hepatocytes. We confirmed upregulated Abcb4 gene expression in seladelpar-treated primary mouse hepatocytes isolated from C57BL/6 mice. We further incubated nonparenchymal liver cells with seladelpar. Although there was a significant increase in the PPARD-responsive genes Pdk4 and Angptl4 in cholangiocytes,Kupffer cells,and hepatic stellate cells,seladelpar did not exert specific liver-protective effects in these cell types. Conclusions: The selective PPARD agonist seladelpar induced PPARD-responsive genes primarily in hepatocytes and cholangiocytes. Seladelpar upregulated Abcb4 in hepatocytes,which might contribute to its beneficial effects in cholestatic liver disorders. View Publication

BackgroundThe cycling intestinal stem cells (ISCs) exhibit radiosensitivity,and their death or impaired regenerative capacity following irradiation may result in intestinal barrier dysfunction. The cystathionine-β-synthase (CBS)/H2S axis plays a critical role in regulating cell proliferation,reactive oxygen species scavenging,and the DNA damage response. However,it remains unclear whether the CBS/H2S axis modulates ISC homeostasis and tissue radiosensitivity. Methods: Intestinal epithelium specific conditional CBS knockout mice were generated by crossing CBSfl/+ mice with Villin-CreERT2 mice. CAGGCre-ER™ mice were crossed with CBSfl/fl mice to achieve CBS knockout in multiple tissues and cell types. The Lgr5-Tdtaomato-Flag mice were generated by CRISPR/Cas9 system. The CBS inhibitor AOAA or the H2S donor GYY4137 was used to treat mice or intestinal crypt organoids. Hematoxylin and eosin,immunohistochemistry,immunofluorescence,Western blot,qRT-PCR,et al. were employed to investigate the role of the CBS/H2S axis in ISCs homeostasis and radiation-induced intestinal damage. Results: Lgr5 + ISCs and progenitor cells expressed higher levels of CBS than differentiated cells. The cecum and colon expressed significant higher CBS levels than the small intestine. Treatment with the H2S donor GYY4137 enhanced the proliferation of intestinal organoids in vitro,while inhibition of CBS by AOAA reduced this effect. Genetic knockout of CBS in the intestinal epithelium or global downregulation of CBS driven by CAGG-CreER™ in vivo did not affect ISC proliferation or differentiation under physiological conditions. Pharmacological regulation of the CBS/H2S axis in vitro failed to protect organoids from radiation-induced damage. Interestingly,administration of AOAA in vivo reduced radiation-induced atrophy of the intestinal mucosa. Furthermore,global downregulation of CBS significantly promoted ISC recovery after irradiation exposure. However,intestinal epithelium-specific CBS knockout did not confer radioprotective effects. Conclusions: Our findings suggest that the CBS/H2S axis contributes to the regulation of ISC homeostasis and represents a potential target for radiation protection,mediated through the intervention of non-epithelial cells. View Publication

The high burden of dilated cardiomyopathy (DCM) in individuals of African descent remains incompletely explained. Here,to explore a genetic basis,we conducted a genome-wide association study in 1,802 DCM cases and 93,804 controls of African genetic ancestry (AFR). A nonsense variant (rs3211938:G) in CD36 was associated with increased risk of DCM. This variant,believed to be under positive selection due to a protective role in malaria resistance,is present in 17% of AFR individuals but <0.1% of European genetic ancestry (EUR) individuals. Homozygotes for the risk allele,who comprise ~1% of the AFR population,had approximately threefold higher odds of DCM. Among those without clinical cardiomyopathy,homozygotes exhibited an 8% absolute reduction in left ventricular ejection fraction. In AFR,the DCM population attributable fraction for the CD36 variant was 8.1%. This single variant accounted for approximately 20% of the excess DCM risk in individuals of AFR compared to those of EUR. Experiments in human induced pluripotent stem cell-derived cardiomyocytes demonstrated that CD36 loss of function impairs fatty acid uptake and disrupts cardiac metabolism and contractility. These findings implicate CD36 loss of function and suboptimal myocardial energetics as a prevalent cause of DCM in individuals of African descent. Genome-wide analysis in individuals of African ancestry identifies a nonsense variant in CD36 associated with increased risk of dilated cardiomyopathy (DCM),partly accounting for the higher incidence of DCM in African-ancestry populations. View Publication

Radiotherapy is a standard treatment of pediatric brain tumors. Though the survival rate has improved for many tumor types,most patients suffer long-term cognitive decline and there is currently no way of preventing radiation-induced damage to healthy brain tissue. Here,we used a human forebrain organoid model to investigate if the α2-adrenoceptor and I1-imidazoline receptor agonist clonidine could prevent radiotoxicity. We found that treatment of organoids with clonidine significantly reduced radiation-induced loss of neural progenitor cells,neurons,astrocytes,and oligodendrocyte lineage cells. Moreover,clonidine reduced overall DNA damage and signs of reactive gliosis in organoids. Our findings demonstrate that pharmacological rescue of radiation neurotoxicity is possible in a human brain organoid model and provides a rationale for future drug repurposing studies aiming to prevent radiation-induced brain injury in children treated with radiotherapy. View Publication