Biology subjects

Orabi, D.

Publications and source records attributed to Orabi, D..

6 recordsLinked to original sources

bioRxiv2025

The Lipid Hydrolase ABHD6 is a Therapeutic Target in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)-Related Hepatocellular Carcinoma

Primary liver cancer accounts for approximately 700,000 deaths worldwide annually ranking third in cancer-related mortality, with hepatocellular carcinoma (HCC) comprising the majority of these tumors. Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently a leading cause of HCC in the United States. We previously identified the lipid hydrolase alpha/beta hydrolase domain 6 (ABHD6) as a key mediator of the development of metabolic syndrome and intimately involved in cell signaling, making it a prime target for investigation in MASLD-related HCC. ABHD6 displays higher expression within HCC tumor cores when compared to adjacent non-tumor liver tissue in human subjects. Using an in vivo antisense oligonucleotide (ASO)-driven knockdown approach, we have shown the inhibition of ABHD6 prevents the development and progression of HCC in an obesity/MASLD-driven mouse model. Additionally, a xenograft model using the human Huh7 cell line displayed reduced tumor engraftment and growth with ABHD6 genetic deletion and small molecule inhibition. ABHD6 knockout cells demonstrated increased levels of bis(monoacylglycerol)phosphates (BMPs), lipids relevant to high fat diet-induced lysosomal dysfunction, and knockout cells also demonstrated altered autophagy and lysosomal activity using in vitro model of saturated fatty acid-induced lipotoxicity. These studies reveal novel lipid signaling mechanisms by which MASLD progresses towards HCC and provide support for ABHD6 as a therapeutic target in HCC. SignificanceWe have identified that alpha/beta hydrolase domain 6 (ABHD6) plays a role in lysosomal membrane lipid remodeling pathways that are relevant in obesity/MASLD-driven HCC. Inhibitors targeting ABHD6 reorganize lysosomal lipid homeostasis to improve outcomes in HCC.

cancer biology↗

bioRxiv2025

Gut Microbe-Derived N-Acyl Serinol Lipids Shape Host Postprandial Metabolic Homeostasis

Although strong evidence links the gut microbiome to metabolic disease, the mechanisms linking microbiota to hormonal and metabolic responses to food are not well understood. After a meal, gut bacteria produce a wide array of small molecule, protein, and lipid metabolites originating from bacterial sources. Annotating physiological function to select gut microbe-derived metabolites is critical to understanding diet-microbe-host interactions, and to developing microbiome-inspired therapies to improve human health. Here, we have investigated the role of a poorly annotated class of gut microbiome-derived lipids called N-acyl amides in postprandial metabolic physiology. Here we show both bacterial overproduction and provision of exogenous N-acyl amides reorganize host hormone-driven metabolic transition after a meal. Moreover, N-acyl amides exert broad effects on the meal- and circadian-related reorganization of gene expression, metabolic hormones, and gut microbiome composition. Collectively, these results demonstrate that microbiota-derived N-acyl amides play a physiologic role in postprandial metabolic homeostasis in the host.

physiology↗

bioRxiv2025

Gut Microbe-Derived Trimethylamine Shapes Circadian Rhythms Through the Host Receptor TAAR5

Elevated levels of the gut microbe-derived metabolite trimethylamine N-oxide (TMAO) are associated with cardiometabolic disease risk. However, the mechanism(s) linking TMAO production to human disease are incompletely understood. Initiation of the metaorganismal TMAO pathway begins when dietary choline and related metabolites are converted to trimethylamine (TMA) by gut bacteria. Gut microbe-derived TMA can then be further oxidized by host flavin-containing monooxygenases to generate TMAO. Previously, we showed that drugs lowering both TMA and TMAO protect mice against obesity via rewiring of host circadian rhythms. Although most mechanistic studies in the literature have focused on the metabolic end product TMAO, here we have instead tested whether the primary metabolite TMA alters host metabolic homeostasis and circadian rhythms via trace amine-associated receptor 5 (TAAR5). Remarkably, mice lacking the host TMA receptor (Taar5-/-) have altered circadian rhythms in gene expression, metabolic hormones, gut microbiome composition, and diverse behaviors. Also, mice genetically lacking bacterial TMA production or host TMA oxidation have altered circadian rhythms. These results provide new insights into diet-microbe-host interactions relevant to cardiometabolic disease, and implicate gut bacterial production of TMA and the host receptor that senses TMA (TAAR5) in the physiologic regulation of circadian rhythms in mice. HIGHLIGHTSO_LIMice lacking the host TMA receptor (Taar5-/-) have altered circadian rhythms. C_LIO_LITaar5-/- mice have altered innate behaviors in a time of day dependent manner. C_LIO_LIThe normal circadian oscillations in the gut microbiome are dysregulated in Taar5-/- mice. C_LIO_LIGenetic deletion of bacterial TMA production or host TMA oxidation shapes circadian rhythms. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=137 HEIGHT=200 SRC="FIGDIR/small/647082v2_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1608forg.highwire.dtl.DTLVardef@6a809aorg.highwire.dtl.DTLVardef@2131f7org.highwire.dtl.DTLVardef@1575559_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2021

A gut microbial metabolite of dietary polyphenols reverses obesity-driven hepatic steatosis

The molecular mechanisms by which dietary fruits and vegetables confer cardiometabolic benefits remain poorly understood. Historically, these beneficial properties have been attributed to the antioxidant activity of flavonoids. Here, we reveal that the host metabolic benefits associated with flavonoid consumption actually hinge on gut microbial metabolism. We show that a single gut microbial flavonoid catabolite is sufficient to reduce diet-induced cardiometabolic disease burden in mice. Dietary supplementation with elderberry extract attenuated obesity and continuous delivery of the catabolite 4-hydroxphenylacetic acid was sufficient to reverse hepatic steatosis. Analysis of human gut metagenomes revealed that under one percent contains a flavonol catabolic pathway, underscoring the rarity of this process. Our study will impact the design of dietary and probiotic interventions to complement traditional cardiometabolic treatment strategies. One-Sentence SummarySelect gut microbes can metabolize flavonoids from a fruit and vegetable diet to monophenolic acids, which improve fatty liver disease. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/460661v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1c4f56borg.highwire.dtl.DTLVardef@1cc4be3org.highwire.dtl.DTLVardef@18a4af5org.highwire.dtl.DTLVardef@3f44a5_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

A Novel Surgical Method for Continuous Intra-Portal Infusion of Gut Microbial Metabolites in Mice

Gut microbial-derived metabolites have been shown to play key roles in human physiology and disease. However, establishing mechanistic links between gut microbial metabolites and disease pathogenesis in animal models presents many challenges. The major route of absorption for microbe-derived small molecules is venous drainage via the portal vein to the liver. In the event of extensive liver first pass- or presystemic hepatic metabolism, the route of administration of these metabolites becomes critical. Here we describe a novel portal vein cannulation technique using a subcutaneously implanted osmotic pump to achieve continuous portal vein infusion in mice. First, the microbial metabolite trimethylamine (TMA) was administered over 4 weeks and compared to a vehicle control. Using a liquid chromatography-tandem mass spectrometry (LC-MS/MS), an increase in peripheral plasma levels of TMA and its host liver-derived co-metabolite trimethylamine-N-oxide (TMAO) were observed in a sexually-dimorphic manner. Next, 4-hydroxyphenylacetic acid (4-HPAA), a structurally distinct microbial metabolite that undergoes extensive hepatic first pass metabolism, was administered intraportally to examine effects on hepatic gene expression. As expected, there was no difference in peripheral plasma 4-HPAA levels yet liver tissue demonstrated higher levels of 4-HPAA when compared to the control group. More importantly, significant changes were observed in hepatic gene expression using an unbiased RNA sequencing approach. Collectively, this work describes a novel method for administering gut microbe-derived metabolites via the portal vein, mimicking their physiologic delivery in vivo. ImportanceRecent efforts have underscored the importance of the gut microbial community as a meta-endocrine organ impacting host physiology through systemic delivery of gut-microbial metabolites [Brown and Hazen, 2015]. Microbial metabolites are first delivered to the liver via the portal vein following venous drainage of the gastrointestinal tract. This route of absorption is often crucial by allowing the liver to biotransfrom these molecules prior to entering the peripheral circulation. Microbial metabolites are frequently studied in animal models by incorporation into diet or drinking water. This method falls short as inconsistent oral intake, inconsistent gastrointestinal absorption, and further modification of the metabolite by gut microbes yield imprecise levels of drug delivery. In efforts to overcome this, the physiological impact of microbial metabolites is often studied by intermittent exogenous administration of a metabolite in a non-physiologically relevant manner such as intravenous injection, intraperitoneal injection, or subcutaneous administration, all placing a relatively large proportion of the metabolite directly into the peripheral circulation. Although these approaches can effectively raise circulating metabolites levels in some cases, they do not mimic the natural delivery of gut microbial-derived small molecules through the portal circulation to the liver. Here we describe a novel surgical method to continuously deliver precise amounts of gut microbial metabolites intraportally to better recapitulate the natural systemic delivery route of microbial metabolites to the liver. This model will improve the interrogation of gut microbial metabolites and their associations to disease by providing an unmatched level of resolution when manipulating the portal blood metabolome.

microbiology↗

bioRxiv2020

Membrane-Bound O-Acyltransferase 7 (MBOAT7) is a Key Regulator of Glycolysis in Clear Cell Renal Carcinoma.

ObjectiveThe most common and deadliest urological cancer is clear cell Renal Cell Carcinoma (ccRCC). ccRCC is characterized by striking reorganization of both carbohydrate and lipid metabolism. It was recently demonstrated that lipid remodeling enzyme Membrane-Bound O-Acyltransferase 7 (MBOAT7) that generates phosphatidylinositol (PI) is important for the ccRCC progression. However, whether MBOAT7-driven PI remodeling is associated with other metabolic alterations commonly found in ccRCC is poorly understood. MethodsMBOAT7 deficient ccRCC cell lines were generated by genome editing, and were characterized by a general reduction in glycolytic capactiy. Using targeted metabolomics approach in Caki-1 cells, we measured the glycolytic intermediates and the relative expression of key glycolytic enzymes. We also measured basal respiration and maximal respiration with MBOAT7 deficiency in the presence of glucose. Lastly, in vivo xenograft studies were performed with parental and MBOAT7 deficient cells. ResultsMBOAT7 deficiency was associated with a reduction in glycolytic gene expression and protein abundance. In parallel, we found that glycolytic intermediates similarly decreased which may contribute to a reduction in glycolysis. MBOAT7 deficiency reduces basal respiration and maximal respiration. Similarly, we see maximum glycolytic capacity also reduced with MBOAT7 loss of function. Finally, the in vivo xenograft demonstrated MBOAT7 knockout significantly increased overall survival and reduced glycolytic HK2 protein abundance in vivo. ConclusionsOur work highlights MBOAT7 as a key regulator of glycolysis in ccRCC. Our data provides additional evidence that suggests MBOAT7 as a novel target to regulate tumor growth in vivo.

cancer biology↗