Nonvesicular sterol transport is a metabolic immune checkpoint that guards dietary lipid uptake
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PROVIDER: PRJNA1160313 | ENA |
REPOSITORIES: ENA
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Project description:The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular functions are not well defined. Here we show that the nonvesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated “accessible” cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and in Th17 cytokine production. Furthermore, Aster-A associates with STIM1 and negatively regulates STIM1-dependent calcium flux during activation of mouse and human T cells. Finally, mucosal Th17 response towards commensals is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells stimulates IL-22 production, which reduces intestinal fatty acid absorption, and confers resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.
2025-07-20 | GSE277067 | GEO
Project description:Dietary nutrients interact with the gene networks to orchestrate adaptive responses during metabolic stress. Tissue metabolic reprogramming is frequently linked to induction of pathways with pathophysiological consequences. Here we identified Baf60a as a diet-sensitive subunit of the SWI/SNF chromatin-remodeling complexes in the liver that links the consumption of fat- and cholesterol-rich diet to elevated plasma cholesterol levels. The expression of Baf60a in the liver was elevated following western diet feeding. Hepatocyte-specific inactivation of Baf60a reduced bile acid production and intestinal cholesterol absorption, and attenuated diet-induced hypercholesterolemia and atherosclerosis in mice. At the mechanistic level, Baf60a stimulates the expression of hepatic genes involved in bile acid synthesis, modification, and transport through a CAR/Baf60a feedforward regulatory loop. Baf60a is required for the recruitment of the SWI/SNF chromatin-remodeling complexes to facilitate an activating epigenetic switch on the CAR target genes. These studies elucidate an unexpected regulatory pathway that mediates the hyperlipidemic and atherogenic effects of western diet consumption. We used microarrays to elucidate the role of hepatic Baf60a in the regulation of lipid metabolism.
2015-10-03 | GSE73709 | GEO
Project description:The intrinsic pathways that control membrane organization in immune cells and the impact of such pathways on cellular functions are not well defined. Here we show that the nonvesicular cholesterol transporter Aster-A links plasma membrane (PM) cholesterol availability in T cells to immune signaling and systemic metabolism. Aster-A is recruited to the PM during T-cell receptor (TCR) activation, where it facilitates the removal of newly generated “accessible” cholesterol. Loss of Aster-A leads to excess PM cholesterol accumulation, resulting in enhanced TCR nano-clustering and signaling, and in Th17 cytokine production. Furthermore, Aster-A associates with STIM1 and negatively regulates STIM1-dependent calcium flux during activation of mouse and human T cells. Finally, mucosal Th17 response towards commensals is restrained by PM cholesterol remodeling. Ablation of Aster-A in T cells stimulates IL-22 production, which reduces intestinal fatty acid absorption, and confers resistance to diet-induced obesity. These findings delineate a multi-tiered regulatory scheme linking immune cell lipid flux to nutrient absorption and systemic physiology.
2025-07-20 | GSE277138 | GEO
Project description:Intestinal cholesterol absorption is an important determinant of systemic cholesterol homeostasis. Niemann-Pick C1 Like 1 (NPC1L1), the target of the drug ezetimibe, is a critical player in dietary cholesterol uptake. But how cholesterol moves within the cell downstream of NPC1L1 is unknown. Here we show that the nonvesicular sterol transporters Aster-B and -C cooperate with NPC1L1 to deliver dietary cholesterol from the gut lumen to the enterocyte ER for chylomicron packaging. Aster proteins are recruited to the enterocyte plasma membrane (PM) in response to NPC1L1-dependent cholesterol accumulation. Mice lacking Asters in intestine have impaired cholesterol absorption, and reduced plasma cholesterol. NanoSIMS imaging and tracer studies reveal delayed lipid trafficking into chylomicrons in Aster-deficient enterocytes. Interestingly, in addition to potently blocking NPC1L1, ezetimibe is also a low-affinity inhibitor of Aster-B and -C but not -A, and the structure of the Aster-C-ezetimibe complex reveals the basis for this selectivity. Our findings support a model in which NPC1L1 enriches dietary cholesterol at the apical PM, and ASTERs subsequently traffic this cholesterol to the ER. The findings identify the enterocyte Aster pathway as potential target for treatment of hypercholesterolemia. Alessandra Ferrari, PhD
2023-12-21 | GSE206780 | GEO
Project description:In cell models, changes in the “accessible” pool of plasma membrane (PM) cholesterol are linked with the regulation of ER sterol synthesis and metabolism by the Aster family of nonvesicular transporters. However, the relevance of such nonvesicular transport mechanisms for lipid homeostasis in vivo has not been defined. Here we reveal two physiological contexts that generate accessible PM cholesterol and engage the Aster pathway in liver: fasting and reverse cholesterol transport (RCT). During fasting, adipose tissue–derived fatty acids activate hepatocyte sphingomyelinase to liberate sequestered PM cholesterol. Aster-dependent cholesterol transport during fasting facilitates cholesteryl ester (CE) formation, cholesterol movement into bile, and VLDL production. During RCT, HDL delivers excess cholesterol to the hepatocyte PM through SR-BI. Loss of hepatic Asters impairs cholesterol movement into feces, raises plasma cholesterol levels, and causes cholesterol accumulation in peripheral tissues. These results reveal fundamental mechanisms by which Aster cholesterol flux contributes to hepatic and systemic lipid homeostasis.
2022-10-24 | GSE206278 | GEO
Project description:Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of cholesterol is critical for maintaining its proper distribution in the cell, yet the underlying mechanisms remain unclear. Here, we show that lipid transfer proteins, namely ORP9, OSBP, and GRAMD1s/Asters (GRAMD1a/GRAMD1b/GRAMD1c), control non-vesicular cholesterol transport at points of contact between the ER and the trans-Golgi network (TGN), thereby maintaining cellular cholesterol distribution. ORP9 localizes to the TGN via interaction between its tandem α-helices and ORP10/ORP11. ORP9 extracts PI4P from the TGN to prevent its overaccumulation and suppresses OSBP-mediated PI4P-driven cholesterol transport to the Golgi. By contrast, GRAMD1s transport excess cholesterol from the Golgi to the ER, thereby preventing its build-up. Cells lacking ORP9 exhibit accumulation of cholesterol at the Golgi, which is further enhanced by additional depletion of GRAMD1s with major accumulation in the plasma membrane. This is accompanied by chronic activation of the SREBP-2 signalling pathway. Our findings reveal the importance of regulated lipid transport at ER-Golgi contacts for maintaining cellular cholesterol distribution and homeostasis.
2023-09-24 | GSE240960 | GEO
Project description:The pyruvate kinase M2 isoform (PKM2) is preferentially expressed in cancer to regulate anabolic metabolism. However, the metabolic requirements of PKM2 in tumorigenesis have yielded contradictory results. Herein we discovered that this glycolytic enzyme regulates lipid homeostasis in cancer cell autonomous manner and at systemic levels. Transmembrane protein 33 (TMEM33) was identified as a downstream effector of PKM2, whose expression level positively correlates with plasma total cholesterol level in vivo. Loss of PKM2 leads to up-regulation of TMEM33, which recruits ring finger protein 5 (RNF5) to promote SCAP ubiquitination and degradation, thereby inhibiting Golgi translocation and activation of sterol regulatory element binding protein 1 (SREBP1). Moreover, global PKM2 knockout promoted allografted tumor growth, at least partially attributes to the elevated plasma cholesterol level caused by increased intestinal Niemann-Pick C1-Like 1 (NPC1L1) to facilitate cholesterol absorption. Collectively, PKM2-TMEM33 axis modulates cell autonomous lipid metabolism by regulating SREBP activation. PKM2 in small intestine plays critical functions in controlling systemic cholesterol level. Overall, our results underscore unappreciated functions of PKM2 in lipid homeostasis and imply that combining an allosteric activator of PKM2 with NPC1L1 inhibitor represents a therapeutic invention for cancer treatment.
2021-08-06 | PXD026434 | Pride
Project description:Hepatic nonvesicular cholesterol transport is critical for systemic lipid homeostasis
| PRJNA849943 | ENA
Project description:Small Heterodimer Partner (SHP/NR0B2) is an unusual orphan nuclear receptor that does not have a DNA binding domain and acts as a co-repressor for many transcriptional factors, including LRH-1, SREBPs, FOXA1, and AhR, which inhibits expression of its target genes. To explore global intestinal functions of SHP, WT and SHP-KO mice were fed for 6 h after fasting overnight. In SHP-KO mice, 1,707 genes were upregulated, and 1,055 genes downregulated by 2-fold or more compared to WT mice. In GO analysis, intestinal genes upregulated with the highest significance were involved in the transport of ions, lipids, and hormones, and in cholesterol metabolic processes; whereas genes downregulated were involved in the cell cycle, the immune response, and apoptosis. Remarkably, expression of genes important for cholesterol absorption, including Npc1l1, sterol biosynthetic genes, including Hmgcr, and key intestinal bile acid transporters, Asbt and Ost-alpha/beta, was altered in SHP-KO mice compared to WT mice. Overall, in this study, SHP was shown to be a gene-specific transcriptional partner of SREBP-2 to epigenetically inhibit cholesterol-regulating genes, including Npc1l1, in the late-fed state.
2019-02-23 | GSE126939 | GEO
Project description:Cooperation between ASTER-dependent nonvesicular transport and NPC1L1 facilitates dietary cholesterol uptake
| PRJNA852178 | ENA