Cardiac-specific VEGFB overexpression reduces lipoprotein lipase activity and improves insulin action in rat heart

2021 ◽  
Author(s):  
Rui Shang ◽  
Nathaniel Lal ◽  
ChaeSyng Lee ◽  
Yajie Zhai ◽  
Karanjit Puri ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Lipoprotein Lipase ◽  
Insulin Action ◽  
Insulin Signalling ◽  
Isolated Heart ◽  
Cardiac Metabolism ◽  
Metabolic Reprogramming ◽  
Flux Analysis

Cardiac muscle utilizes multiple sources of energy including glucose and fatty acid (FA). The heart cannot synthesize FA and relies on obtaining it from other sources, with lipoprotein lipase (LPL) breakdown of lipoproteins suggested to be a key source of FA for cardiac use. Recent work has indicated that cardiac vascular endothelial growth factor B (VEGFB) overexpression expands the coronary vasculature and facilitates metabolic reprogramming that favours glucose utilization. We wanted to explore whether this influence of VEGFB on cardiac metabolism involves regulation of LPL activity with consequent effects on lipotoxicity and insulin signalling. The transcriptomes of rats with and without cardiomyocyte-specific overexpression of human VEGFB were compared by using RNA-sequencing. Isolated perfused hearts or cardiomyocytes incubated with heparin were used to enable measurement of LPL activity. Untargeted metabolomic analysis was performed for quantification of cardiac lipid metabolites. Cardiac insulin sensitivity was evaluated using fast-acting insulin. Isolated heart and cardiomyocytes were used to determine transgene-encoded VEGFB isoform secretion patterns and mitochondrial oxidative capacity using high-resolution respirometry and extracellular flux analysis. In vitro, primary transgenic cardiomyocytes incubated overnight and thus exposed to abundantly secreted VEGFB isoforms in the absence of any in vivo confounding regulators of cardiac metabolism demonstrated higher basal oxygen consumption. In the whole heart, VEGFB overexpression induced an angiogenic response that was accompanied by limited cardiac LPL activity through multiple mechanisms. This was associated with a lowered accumulation of lipid intermediates, diacylglycerols and lysophosphatidylcholine, that are known to influence insulin action. In response to exogenous insulin, transgenic hearts demonstrated increased insulin sensitivity. In conclusion, the interrogation of VEGFB function on cardiac metabolism uncovered an intriguing and previously unappreciated effect to lower LPL activity and prevent lipid metabolite accumulation to improve insulin action. VEGFB could be a potential cardioprotective therapy to treat metabolic disorders, for example diabetes.

scholarly journals Dynamic regulation of mitochondrial pyruvate metabolism Is necessary for orthotopic pancreatic tumor growth

2021 ◽  
Author(s):  
Nancy P Echeverri Ruiz ◽  
Vijay Mohan ◽  
Jinghai Wu ◽  
Sabina Scott ◽  
McKenzie Kreamer ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Flux Analysis ◽  
Dynamic Regulation ◽  
Environmental Signals ◽  
Substitution Mutations ◽  
Deficient Mice

Abstract BackgroundPyruvate dehydrogenase complex (PDC) plays a central role in carbohydrate metabolism, linking cytoplasmic glycolysis to the mitochondrial tricarboxylic acid (TCA) cycle. PDC is a conserved E1-E2-E3 dehydrogenase with a PDHA1 and PDHB heterotetramer functioning as the E1 subunit. PDHA1 contains three serine residues that can be reversibly phosphorylated by a dedicated family of four inhibitory pyruvate dehydrogenase kinases (PDHK1-4) and two reactivating phosphatases (PDP1,2). Hypoxia induces the expression of PDHK1 and PDHK3 and hyperphosphorylates PDHA1. The role of PDC in metabolic reprogramming and tumor progression appears to be for the integration of oncogenic and environmental signals which supports tumor growth. MethodsTo isolate the function of the serine-dependent regulation pf PDC, we engineered MiaPaca2 cells to express PDHA1 protein with either intact serines at positions 232, 293 and 300, or all the combinations of non-phosphorylatable alanine substitution mutations. These lines were compared in vitro for biochemical response to hypoxia by western blot, metabolic activity by biochemical assay and Seahorse XF flux analysis, and growth in media with reduced exogenous metabolites. The lines were also tested for growth in vivo after orthotopic injection into the pancreata of immune-deficient mice. ResultsIn this family of cells with non-phosphorylatable PDHA1 we found reduced hypoxic phosphorylation of PDHA1, decreased PDH enzymatic activity in normoxia and hypoxia, decreased mitochondrial function by Seahorse flux assay, reduced in vitro growth of cells in media depleted of lipids, and reduced growth of tumors after orthotopic transplantation of cells into the pancreata of immune-deficient mice. ConclusionsWe found that any substitution of alanine for serine at regulatory sites generated a hypomorphic PDC. However, the reduced PDC activity was insensitive to further reduction in hypoxia. These cells had very modest reduction of growth in vitro, but were significantly compromised in their growth as tumors, indicating that dynamic PDC adaptation to microenvironmental conditions is necessary for optimal pancreatic cancer growth in vivo.

Heparin

1985 ◽  
Vol 05 (03) ◽  
pp. 121-126
Author(s):  
L. B. Jaques
Keyword(s):  
Lipoprotein Lipase ◽  
Antithrombin Iii

ZusammenfassungIn vivo bewirkt Heparin das Auftreten einer Lipoprotein-Lipase, einer Diaminoxydase (Histaminase) und anderer Enzyme. In Tierversuchen konnten viele günstige Wirkungen von Heparin und Heparinoiden aufgezeigt werden, wie z.B. Schutzeffekte gegen toxische Medikamente und Prozeduren, gegen Überempfindlichkeitsreaktionen, Änderungen von Hormoneffekten und die Erhöhung der negativen elektrischen Ladung von Körperzellen. Die Einzelwirkungen sind für bestimmte Kettenstrukturen spezifisch. Während Heparin in vitro gerinnungshemmend wirksam ist, zeigt der Vergleich der gerinnungshemmenden Wirkung in der Blutzirkulation mit der chemischen Konzentration im Blut, daß in vivo eine Aktivierung von nicht gerinnungshemmend aktiven Fraktionen bzw. Heparinketten erfolgt. Heparin wird rasch von den Zellen des RES-Systems gegen einen Konzentrationsgradienten aufgenommen, so daß in vivo die Heparinkonzentration im Gefäßendothel lOOOfach höher ist als im Blut.Die Fixierung des Heparins im Endothel vermehrt das elektronegative Potential des Endothels. Diese Wirkung und andere Wirkungen (die Aktivierung von Antithrombin III etc.) sind lokal die Basis der thromboseverhütenden Heparinwirkung. Demnach ist das Endothel das Zielorgan für Heparin.

scholarly journals GCH1 induces immunosuppression through metabolic reprogramming and IDO1 upregulation in triple-negative breast cancer

2021 ◽  
Vol 9 (7) ◽  
pp. e002383
Author(s):  
Jin-Li Wei ◽  
Si-Yu Wu ◽  
Yun-Song Yang ◽  
Yi Xiao ◽  
Xi Jin ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Molecular Taxonomy ◽  
Underlying Mechanism ◽  
Metabolic Reprogramming ◽  
Sequencing Data ◽  
Aryl Hydrocarbon

PurposeRegulatory T cells (Tregs) heavily infiltrate triple-negative breast cancer (TNBC), and their accumulation is affected by the metabolic reprogramming in cancer cells. In the present study, we sought to identify cancer cell-intrinsic metabolic modulators correlating with Tregs infiltration in TNBC.Experimental designUsing the RNA-sequencing data from our institute (n=360) and the Molecular Taxonomy of Breast Cancer International Consortium TNBC cohort (n=320), we calculated the abundance of Tregs in each sample and evaluated the correlation between gene expression levels and Tregs infiltration. Then, in vivo and in vitro experiments were performed to verify the correlation and explore the underlying mechanism.ResultsWe revealed that GTP cyclohydrolase 1 (GCH1) expression was positively correlated with Tregs infiltration and high GCH1 expression was associated with reduced overall survival in TNBC. In vivo and in vitro experiments showed that GCH1 increased Tregs infiltration, decreased apoptosis, and elevated the programmed cell death-1 (PD-1)-positive fraction. Metabolomics analysis indicated that GCH1 overexpression reprogrammed tryptophan metabolism, resulting in L-5-hydroxytryptophan (5-HTP) accumulation in the cytoplasm accompanied by kynurenine accumulation and tryptophan reduction in the supernatant. Subsequently, aryl hydrocarbon receptor, activated by 5-HTP, bound to the promoter of indoleamine 2,3-dioxygenase 1 (IDO1) and thus enhanced the transcription of IDO1. Furthermore, the inhibition of GCH1 by 2,4-diamino-6-hydroxypyrimidine (DAHP) decreased IDO1 expression, attenuated tumor growth, and enhanced the tumor response to PD-1 blockade immunotherapy.ConclusionsTumor-cell-intrinsic GCH1 induced immunosuppression through metabolic reprogramming and IDO1 upregulation in TNBC. Inhibition of GCH1 by DAHP serves as a potential immunometabolic strategy in TNBC.

scholarly journals Mitochondrial arginase-2 is essential for IL-10 metabolic reprogramming of inflammatory macrophages

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jennifer K. Dowling ◽  
Remsha Afzal ◽  
Linden J. Gearing ◽  
Mariana P. Cervantes-Silva ◽  
Stephanie Annett ◽  
...  
Keyword(s):  
Metabolic Regulation ◽  
Mitochondrial Dynamics ◽  
Interleukin 10 ◽  
Metabolic Reprogramming ◽  
In Vivo Model ◽  
Macrophage Polarisation ◽  
Inflammatory Status ◽  
Inflammatory Macrophages

AbstractMitochondria are important regulators of macrophage polarisation. Here, we show that arginase-2 (Arg2) is a microRNA-155 (miR-155) and interleukin-10 (IL-10) regulated protein localized at the mitochondria in inflammatory macrophages, and is critical for IL-10-induced modulation of mitochondrial dynamics and oxidative respiration. Mechanistically, the catalytic activity and presence of Arg2 at the mitochondria is crucial for oxidative phosphorylation. We further show that Arg2 mediates this process by increasing the activity of complex II (succinate dehydrogenase). Moreover, Arg2 is essential for IL-10-mediated downregulation of the inflammatory mediators succinate, hypoxia inducible factor 1α (HIF-1α) and IL-1β in vitro. Accordingly, HIF-1α and IL-1β are highly expressed in an LPS-induced in vivo model of acute inflammation using Arg2−/− mice. These findings shed light on a new arm of IL-10-mediated metabolic regulation, working to resolve the inflammatory status of the cell.

scholarly journals TAMI-06. PRECLINICAL MODELS REVEAL BRAIN-MICROENVIRONMENT SPECIFIC METABOLIC DEPENDENCIES IN GLIOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii214-ii214
Author(s):  
Jenna Minami ◽  
Nicholas Bayley ◽  
Christopher Tse ◽  
Henan Zhu ◽  
Danielle Morrow ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Cultured Cells ◽  
Tumor Biology ◽  
Metabolic Reprogramming ◽  
Neoplastic Progression ◽  
Extracellular Milieu ◽  
Metabolic Defects ◽  
Metabolic Heterogeneity

Abstract Metabolic reprogramming is a hallmark of cancer, and malignant cells must acquire metabolic adaptations to fuel neoplastic progression. Mutations or changes in metabolic gene expression can impose nutrient dependencies in tumors, and even in the absence of metabolic defects, cancer cells can become auxotrophic for particular nutrients or metabolic byproducts generated by other cells in the tumor microenvironment (TME). Conventional cell lines do not recapitulate the metabolic heterogeneity of glioblastoma (GBM), while primary cultured cells do not account for the influences of the microenvironment and the blood brain barrier on tumor biology. Additionally, these systems are under strong selective pressure divergent from that in vivo, leading to reduced heterogeneity between cultured tumor cells. Here, we describe a biobank of direct-from-patient derived orthotopic xenografts (GliomaPDOX) and gliomaspheres that reveal a subset of gliomas that, while able to form in vivo, cannot survive in vitro. RNA sequencing of tumors that can form both in vivo and in vitro (termed “TME-Indifferent”) compared to that of tumors that can only form in vivo (termed “TME-Dependent”) revealed transcriptional changes associated with altered nutrient availability, emphasizing the unique metabolic programs impacted by the tumor microenvironment. Furthermore, TME-dependent tumors lack metabolic signatures associated with nutrient biosynthesis, thus indicating a potential dependency of these tumors on scavenging specific nutrients from the extracellular milieu. Collectively, these data emphasize the metabolic heterogeneity within GBM, and reveal a subset of gliomas that lack metabolic plasticity, indicating a potential brain-microenvironment specific metabolic dependency that can be targeted for therapy.

scholarly journals NDUFA4L2 promotes glioblastoma progression, is associated with poor survival, and can be effectively targeted by apatinib

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Zheng Chen ◽  
Xiangyu Wei ◽  
Xueyi Wang ◽  
Xuan Zheng ◽  
Bowen Chang ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Hypoxia Inducible Factor ◽  
Mitochondrial Respiratory Chain ◽  
Metabolic Reprogramming ◽  
Tumor Cell Apoptosis ◽  
Survival Gene ◽  
A Subunit ◽  
Tumor Types

AbstractNADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2 (NDUFA4L2) is a subunit of Complex I of the mitochondrial respiratory chain, which is important in metabolic reprogramming and oxidative stress in multiple cancers. However, the biological role and molecular regulation of NDUFA4L2 in glioblastoma (GBM) are poorly understood. Here, we found that NDUFA4L2 was significantly upregulated in GBM; the elevated levels were correlated with reduced patient survival. Gene knockdown of NDUFA4L2 inhibited tumor cell proliferation and enhanced apoptosis, while tumor cells initiated protective mitophagy in vitro and in vivo. We used lentivirus to reduce expression levels of NDUFA4L2 protein in GBM cells exposed to mitophagy blockers, which led to a significant enhancement of tumor cell apoptosis in vitro and inhibited the development of xenografted tumors in vivo. In contrast to other tumor types, NDUFA4L2 expression in GBM may not be directly regulated by hypoxia-inducible factor (HIF)-1α, because HIF-1α inhibitors failed to inhibit NDUFA4L2 in GBM. Apatinib was able to effectively target NDUFA4L2 in GBM, presenting an alternative to the use of lentiviruses, which currently cannot be used in humans. Taken together, our data suggest the use of NDUFA4L2 as a potential therapeutic target in GBM and demonstrate a practical treatment approach.

scholarly journals Lactate secreted by PKM2 upregulation promotes Galectin-9-mediated immunosuppression via inhibiting NF-κB pathway in HNSCC

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Hanyue Chang ◽  
Qiaoshi Xu ◽  
Jiayi Li ◽  
Mingyu Li ◽  
Zhiyuan Zhang ◽  
...  
Keyword(s):  
Critical Role ◽  
Lactate Production ◽  
Metabolic Reprogramming ◽  
Migration And Invasion ◽  
Histone Deacetylase 3 ◽  
Proliferation And Metastasis ◽  
Immunosuppressive Microenvironment ◽  
Transcriptional Complex

AbstractPyruvate kinase M2 as a key rate-limiting enzyme in glycolysis, it plays a critical role in metabolic reprogramming and carcinogenesis. However, whether PKM2 can promote immunosuppressive microenvironment formation remains unknown in head and neck squamous cell carcinoma (HNSCC). PKM2 expression was detected using immunohistochemical staining. The biological functions of PKM2 were investigated in vitro and in vivo. Lactate production and the expression of Galectin-9, a critical immunosuppression molecule, were detected after PKM2 knockdown and overexpression in HNSCC cells. The mechanism of lactate regulating Galectin-9 expression through NF-κB signaling was explored in vitro. Overexpression of PKM2 correlates with poor prognosis in HNSCC patients. Silencing PKM2 markedly inhibits proliferation and metastasis capacity in vivo and in vitro, and vice versa. The glycolysis and glycolytic capacity are significantly decreased after PKM2 silencing. Lactate secretion induced by PKM2 significantly promotes migration and invasion capacity. Furthermore, a positive correlation between PKM2 and Galectin-9 expression is observed in HNSCC tissues. The induction of Galectin-9 expression by PKM2 can be affected by a lactate transporter inhibitor. Mechanically, lactate impeded the suppressive transcriptional complex formation of NF-κB and histone deacetylase 3 (HDAC3), which released the transcription of Galectin-9 mediated by NF-κB signaling. Our findings demonstrate that lactate produced by PKM2 upregulation promotes tumor progression and Galectin-9-mediated immunosuppression via NF-κB signaling inhibition in HNSCC, which bridges metabolism and immunosuppression. The novel PKM2-lactate-Galectin-9 axis might be a potential therapeutic target in HNSCC.

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