Amy Deik

The limited therapeutic options for metabolic dysfunction-associated steatotic liver disease (MASLD) underscore the need for deeper mechanistic insight and new treatment strategies. Here, we identify the orphan G protein-coupled receptor GPR146 as a regulator of hepatic steatosis through adipose–liver crosstalk. Human genetic analyses link the GPR146 locus to circulating markers of liver injury and inflammation. In mice, both constitutive and acute GPR146 depletion protect against diet-induced obesity and hepatic steatosis. Notably, adipose-specific, but not liver-specific, GPR146 deletion reduces hepatic lipid accumulation by limiting free fatty acid (FFA) influx. Mechanistically, GPR146 promotes adipogenesis in preadipocytes via Gαq-PKC-AKT signaling, increasing lipid storage capacity, and enhances lipolysis in mature adipocytes through ERK activation, elevating circulating FFA. Together, these coordinated actions increase FFA delivery to the liver, promoting triglyceride accumulation. Our findings establish GPR146 as a pleiotropic regulator of adipose tissue biology and a potential therapeutic target for MASLD.

Here authors report intraoperative sampling of blood entering and leaving the lung allowing direct assessment of nutrient use by lung cancer.

Cancer cell fate has been widely ascribed to mutational changes within protein-coding genes associated with tumor suppressors and oncogenes. In contrast, the mechanisms through which the biophysical properties of membrane lipids influence cancer cell survival, dedifferentiation and metastasis have received little scrutiny. Here, we report that cancer cells endowed with high metastatic ability and cancer stem cell-like traits employ ether lipids to maintain low membrane tension and high membrane fluidity. Using genetic approaches and lipid reconstitution assays, we show that these ether lipid-regulated biophysical properties permit non-clathrin-mediated iron endocytosis via CD44, resulting in significant increases in intracellular redox-active iron and enhanced ferroptosis susceptibility. Using a combination of in vitro three-dimensional microvascular network systems and in vivo animal models, we show that loss of ether lipids from plasma membranes also strongly attenuates extravasation, metastatic burden and cancer stemness. These findings illuminate a mechanism whereby ether lipids in carcinoma cells serve as key regulators of malignant progression while conferring a unique vulnerability that can be exploited for therapeutic intervention.

Improved ex vivo expansion of human haematopoietic stem cells (HSCs) would considerably advance transplantation and genome-engineered therapies, yet existing culture methods still allow substantial HSC loss. Here we show that this attrition is driven largely by ferroptosis, a metabolically regulated, iron-dependent cell-death pathway, and that it can be blocked to augment HSC expansion. Inhibiting ferroptosis with liproxstatin-1 or ferrostatin-1 markedly increases the expansion of cord blood and adult HSCs consistently across donors in both widely used serum-free cultures and recently reported chemically defined conditions. The expanded cells retain phenotypic and molecular stem cell identity and mediate improved durable, multilineage engraftment in xenotransplanted mice without genotoxicity or aberrant haematopoiesis. Mechanistically, ferroptosis blockade is accompanied by upregulated ribosome biogenesis and cholesterol synthesis, increasing levels of 7-dehydrocholesterol—a potent endogenous ferroptosis inhibitor that itself promotes HSC expansion. Crucially, this approach enhances yields of therapeutically genome-modified HSCs, paving a path for clinical applications.

The next generation of mRNA vaccines must address several limitations, including enhancing vaccine potency and reducing toxicity. Here we develop a class of degradable, cyclic amino ionizable lipids via sequential combinatorial chemistry and rational design. Lipid nanoparticles (LNPs) formulated with the top-performing ionizable lipid, AMG1541, elicited similar protective neutralization antibody titres against an H3 influenza antigen when compared with the FDA-approved ionizable lipid SM-102 at a 100-fold lower dose, with enhanced clearance in vivo. AMG1541 mRNA LNPs substantially reduced expression in the liver following intramuscular injection, mitigating the associated toxicity. We also observed improved mRNA delivery to antigen-presenting cells at the injection site and the draining lymph node, leading to stronger germinal centre reactions. Structure–activity relationship studies suggest that cyclic headgroups and β-amino alcohols facilitate interactions with the mRNA backbone and enhance endosomal escape. The formulations developed here significantly enhance the potency of mRNA vaccines, and our structural insights may guide the development of next-generation vaccine delivery systems.

Introduction Human metabolomics has made significant strides in understanding metabolic changes and their implications for human health, with promising applications in diagnostics and treatment, particularly regarding the gut microbiome. However, progress is hampered by issues with data comparability and reproducibility across studies, limiting the translation of these discoveries into practical applications. Objectives This study aims to evaluate the fit-for-purpose of a suite of human stool samples as potential candidate reference materials (RMs) and assess the state of the field regarding harmonizing gut metabolomics measurements. Methods An interlaboratory study was conducted with 18 participating institutions. The study allowed for the use of preferred analytical techniques, including liquid chromatography-mass spectrometry (LC–MS), gas chromatography-mass spectrometry (GC–MS), and nuclear magnetic resonance (NMR). Results Different laboratories used various methods and analytical platforms to identify the metabolites present in human stool RM samples. The study found a 40% to 70% recurrence in the reported top 20 most abundant metabolites across the four materials. In the full annotation list, the percentage of metabolites reported multiple times after nomenclature standardization was 36% (LC–MS), 58% (GC–MS) and 76% (NMR). Out of 9,300 unique metabolites, only 37 were reported across all three measurement techniques. Conclusion This collaborative exercise emphasized the broad chemical survey possible with multi-technique approaches. Community engagement is essential for the evaluation and characterization of common materials designed to facilitate comparability and ensure data quality underscoring the value of determining current practices, challenges, and progress of a field through interlaboratory studies. Graphical abstract

: Angiopoietin-like 3 (ANGPTL3) is a key regulator of lipoprotein metabolism, known for its potent inhibition on intravascular lipoprotein and endothelial lipase activities. Recent studies have shed light on the cellular functions of ANGPTL3. However, the precise mechanism underlying its regulation of cellular lipid metabolism remains elusive. We recently reported that ANGPTL3 interacts with the chromatin regulator SMARCAL1, which plays a pivotal role in maintaining cellular lipid homeostasis. Here, through a combination of in vitro and in vivo functional analyses, we provide evidence that ANGPTL3 indeed influences cellular lipid metabolism. Increased expression of Angptl3 prompted the formation of lipid droplets (LDs) in response to slow growth conditions. Notably, under the conditions, Angptl3 accumulated within cytoplasmic peroxisomes, where it interacts with SmarcAL1, which translocated from nucleus as observed previously. This translocation induced changes in gene expression favoring triglyceride (TG) accumulation. Indeed, ANGPTL3 gene knockout (KO) in human cells increased the expression of key lipid genes, which could be linked to elevated nuclear localization of SMARCAL1, whereas the expression of these genes decreased in SMARCAL1 KO cells. Consistent with these findings, the injection of Angptl3 protein to mice led to hepatic fat accumulation derived from circulating blood, a phenotype likely indicative of its long-term effect on blood TG, linked to SmarcAL1 activities. Thus, our results suggest that the Angptl3-SmarcAL1 pathway may confer the capacity for TG storage in cells in response to varying growth states, which may have broad implications for this pathway in regulating energy storage and trafficking.

The tumor microenvironment is a determinant of cancer progression and therapeutic efficacy, with nutrient availability playing an important role. Although it is established that the local abundance of specific nutrients defines the metabolic parameters for tumor growth, the factors guiding nutrient availability in tumor compared to normal tissue and blood remain poorly understood. To define these factors in renal cell carcinoma (RCC), we performed quantitative metabolomic and comprehensive lipidomic analyses of tumor interstitial fluid (TIF), adjacent normal kidney interstitial fluid (KIF), and plasma samples collected from patients. TIF nutrient composition closely resembles KIF, suggesting that tissue-specific factors unrelated to the presence of cancer exert a stronger influence on nutrient levels than tumor-driven alterations. Notably, select metabolite changes consistent with known features of RCC metabolism are found in RCC TIF, while glucose levels in TIF are not depleted to levels that are lower than those found in KIF. These findings inform tissue nutrient dynamics in RCC, highlighting a dominant role of non-cancer-driven tissue factors in shaping nutrient availability in these tumors.

Background: APOE ε4 is the strongest genetic risk factor for late‐onset Alzheimer’s disease (AD). The contribution of microglial APOE4 to AD pathogenesis is unknown, although APOE has the most enriched gene expression in neurodegenerative microglia (MGnD).Method: Generation of CX3CR1‐CRE^ERT2 mice crossed to APOE‐KI(E3 and E4)^fl/fl: APP/PS1 and APOE‐KI(E3 and E4)^fl/fl: P301S mice. Microglia and astrocytes were isolated and sequenced using either bulk RNA‐seq (MGnD‐Paradigm) or single‐cell RNA‐seq. Crosstalk between cells was determined using the NichenetR database and validated using 1) recombinant Lgals3 intracranial injection into APP/PS1 mice and 2) adoptive transfer of microglia, from APOE3‐KI, APOE4‐KI, and APOE4‐cKO mice challenged with labeled apoptotic neurons, into WT mice and isolation of astrocytes. Validation in the brain of AD donors carrying the APOE e3/3 and e3/4 alleles.Result: Here we show, in mice and in humans, a negative role of microglial APOE4 in the induction of MGnD response to neurodegeneration. Deletion of microglial APOE4 restores MGnD phenotype, associated with neuroprotection in P301S tau transgenic mice, and decreases pathology in APP/PS1 mice. MGnD‐astrocyte crosstalk associated with b‐amyloid (Ab) plaque encapsulation and clearance is mediated via Lgals3 signaling following microglial APOE4 deletion. In the brain of AD donors carrying the APOE ε4 allele, we found a sex‐dependent reciprocal induction of AD risk factors associated with suppression of MGnD genes in females, including LGALS3, as compared to APOE ε3/3 carriers. Mechanistically, APOE4‐mediated induction of ITGB8‐TGFb signaling impairs MGnD response via upregulation of TGFb‐mediated microglial homeostatic checkpoints, including INPP5D. Microglial deletion of Inpp5d restores MGnD‐astrocyte crosstalk and facilitates plaque clearance in APP/PS1 mice. Genetic and pharmacological blocking of ITGB8‐TGFb signaling enhanced MGnD response associated with increased plaque clearance in AD mice.Conclusion: We identify the microglial APOE4‐ITGB8‐TGFb pathway as a negative regulator of microglia‐astrocyte response to AD pathology, and restoring MGnD phenotype via blocking ITGB8‐TGFb signaling may provide new molecular targets to modulate and restore functional microglia in AD.

Background: APOE4 is the major genetic risk factor for late‐onset Alzheimer Disease (AD). APOE signaling is critical for the transition of homeostatic microglia to the neurodegenerative phenotype (MGnD). The intrinsic role of APOE4 in microglia and its contribution to AD is unclear.Method: Generation of Cx3cr1‐CRE^ERT2 mice crossed to APOE‐KI(APOE3 and APOE4)^fl/fl injected with labeled apoptotic neurons (MGnD‐Pardigm) on WT or APP/PS1 background. Microglia and astrocytes were isolated and sequenced using either bulk RNA‐seq (MGnD‐Paradigm) or single‐cell RNA‐seq (APP/PS1). Crosstalk between cells was determined using the NichenetR database and validated using 1) Recombinant Lgals3 intracranial injection into APP/PS1 mice and 2) Adoptive transfer of microglia, from APOE3‐KI, APOE4‐KI and APOE4‐cKO mice challenged with labeled apoptotic neurons, into WT mice and isolation of astrocytes.Result: Expression of APOE4 in microglia impaired MGnD‐transition in response to neurodegeneration and in APP/PS1 mice. Conditional deletion of APOE4 in microglia restored MGnD phenotype and reduced plaque pathology. Furthermore, increased astrocytic recruitment towards plaques and their activation by increased Gfap and Serpina3n expression was identified. Microglial Lgals3 was determined as critical crosstalk effector to promote astrocyte response to plaque pathology and acute neurodegeneration. AD female APOE4 carriers showed impaired induction of MGnD signature genes and astrocyte activation, including LGALS3 and GFAP respectively, supporting a conserved disease mechanism in a sex‐dependent manner.Conclusion: APOE4 impairs MGnD‐microglia in AD and prevents their crosstalk with astrocytes. Lgals3 is identified as important positive regulator for microglia–astrocyte crosstalk in response to AD pathology and provides a potential therapeutic target for treatment of AD.