Metabolisms
Abstract
Uterine leiomyomas cause heavy menstrual bleeding, anemia, and pregnancy loss in approximately 10 million US women. Driver mutations in the transcriptional mediator complex subunit 12 (MED12) gene in uterine myometrial cells initiate 70% of leiomyoma that grow in a progesterone-dependent manner. We showed a distinct chromatin occupancy landscape of MED12 in mutant (mut)- vs wild-type (wt)-MED12 leiomyoma. Integration of cistromic and transcriptomic data identified tryptophan 2,3-dioxygenase (TDO2) as the top mut-MED12 target gene, which was significantly upregulated in mut-MED12 leiomyoma when compared to adjacent myometrium and wt-MED12 leiomyoma. TDO2 catalyzes the conversion of tryptophan to kynurenine, an aryl hydrocarbon receptor (AHR) ligand that we confirmed to be significantly elevated in mut-MED12 leiomyoma. Treatment of primary mut-MED12 leiomyoma cells with tryptophan or kynurenine stimulated AHR nuclear translocation, increased proliferation, inhibited apoptosis, and induced AHR-target gene expression, whereas blocking the TDO2-kynurenine-AHR pathway by siRNA or pharmacological treatment abolished these effects. Progesterone receptor regulated the expression of AHR and its target genes. In vivo, TDO2 expression positively correlated with the expression of genes crucial for leiomyoma growth. In summary, activation of the TDO2-kynurenine-AHR pathway selectively in mut-MED12 leiomyoma promotes tumor growth and may inform the future development of targeted treatments and precision medicine.
Authors
Azna Zuberi, Yongchao Huang, Ariel J. Dotts, Helen Wei, John S. Coon V, Shimeng Liu, Takashi Iizuka, Olivia Wu, Olivia Sotos, Priyanka Saini, Debabrata Chakravarti, Thomas G. Boyer, Yang Dai, Serdar E. Bulun, Ping Yin
Abstract
Glutaminolysis is a hallmark of the activation and metabolic reprogramming of T cells. Isotopic tracer analyses of antigen-activated effector CD8+ T cells revealed that glutamine is the principal carbon source for the biosynthesis of polyamines putrescine, spermidine and spermine. These metabolites play critical roles in activation-induced T-cell proliferation, as well as for the production of hypusine, which is derived from spermidine and is covalently linked to the translation elongation factor eIF5A. Here, we demonstrated that the glutamine-polyamine-hypusine axis controls the expression of CD69, an important regulator of tissue resident memory T cells (TRM). Inhibition of this circuit augmented the development of TRM cells ex vivo and in vivo in the bone marrow, a well-established niche for TRM cells. Furthermore, blocking the polyamine-hypusine axis augmented CD69 expression and IFN-γ and TNF-α production in human CD8+ T cells from peripheral blood and sarcoma tumor infiltrating lymphocytes, as well as in human CD8+ CAR-T cells. Collectively, these findings support the notion that the polyamine-hypusine circuit can be exploited to modulate TRM cells for therapeutic benefit.
Authors
Aya G. Elmarsafawi, Rebecca S. Hesterberg, Mario R. Fernandez, Chunying Yang, Lancia N.F. Darville, Min Liu, John M. Koomen, Otto Phanstiel IV, Reginald Atkins, John E. Mullinax, Shari A. Pilon-Thomas, Frederick L. Locke, Pearlie K. Epling-Burnette, John L. Cleveland
Abstract
Acyl-CoA thioesterase 1 (ACOT1) catalyzes the hydrolysis of long-chain acyl-CoAs to free fatty acids and coenzyme A and is typically upregulated in obesity. Whether targeting ACOT1 in the setting of high-fat diet induced obesity would be metabolically beneficial is not known. Here we report that male and female ACOT1KO mice are partially protected from high-fat diet induced obesity, an effect associated with increased energy expenditure without alterations in physical activity or food intake. In males, ACOT1 deficiency increased mitochondrial uncoupling protein-2 (UCP2) protein abundance, while reducing 4-hydroxynonenal (4-HNE), a marker of oxidative stress, in white adipose tissue and liver of high-fat fed mice. Moreover, concurrent knockdown of UCP2 with ACOT1 in hepatocytes prevented increases in oxygen consumption observed with ACOT1 knockdown during high lipid loading, suggesting that UCP2-induced uncoupling may increase energy expenditure to attenuate weight gain. Together, these data indicate that targeting ACOT1 may be effective for obesity prevention during caloric excess by increasing energy expenditure.
Authors
Timothy D. Heden, Mallory P. Franklin, Christina Dailey, Mara T. Mashek, Chen Chen, Douglas G. Mashek
Abstract
Metabolic mechanisms underlying the heterogeneity of major adverse cardiovascular events (MACE) risk in individuals with type 2 diabetes mellitus (T2D) remain unclear. We hypothesized that circulating metabolites reflecting mitochondrial dysfunction predict incident MACE in T2D. Targeted mass-spectrometry profiling of 60 metabolites was performed on baseline plasma from TECOS (discovery) and EXSCEL (validation) trial biomarker substudy cohorts. A principal components analysis metabolite factor comprised of medium-chain acylcarnitines was associated with MACE in TECOS and validated in EXSCEL, with higher levels associated with higher MACE risk. Meta-analysis showed that long-chain acylcarnitines and dicarboxylacylcarnitines were also associated with MACE. Metabolites remained associated with MACE in multivariate models and favorably changed with exenatide therapy. A third cohort (CATHGEN) with T2D assessed whether these metabolites improved discriminative capability multivariate for MACE; nine metabolites (medium- and long-chain acylcarnitines and one dicarboxylacylcarnitine) were associated with time-to-MACE in CATHGEN. Addition of these metabolites to clinical models minimally improved the discriminative capability for MACE but did significantly down reclassify risk. Thus, metabolites reporting on dysregulated mitochondrial fatty acid oxidation are higher in individuals with T2D who experience subsequent MACE. These biomarkers may improve CV risk prediction models, be therapy responsive, and highlight emerging risk mechanisms.
Authors
Jessica A. Regan, Robert J. Mentz, Maggie Nguyen, Jennifer B. Green, Lauren K. Truby, Olga Ilkayeva, Christopher Newgard, John B. Buse, Harald Sourij, C. David Sjöström, Naveed Sattar, Robert W. McGarrah, Yinggan Zheng, Darren K. McGuire, Eberhard Standl, Paul Armstrong, Eric Peterson, Adrian Hernandez, Rury R. Holman, Svati H. Shah
Abstract
Dyslipidemia in obesity results from excessive production and impaired clearance of triglyceride (TG)-rich lipoproteins, which is particularly pronounced in the postprandial state. Here, we investigated the impact of Roux-en-Y gastric bypass (RYGB) surgery on the postprandial VLDL1 and VLDL2 apoB and TG kinetics and their relationship with insulin responsiveness indices. 24 obese non-diabetic RYGB surgery patients underwent a lipoprotein kinetics study during a mixed meal test and a hyperinsulinemic-euglycemic clamp study before the surgery, and one year later. A physiologically based computational model was developed to investigate the impact of RYGB surgery and plasma insulin on postprandial VLDL kinetics. After the surgery, VLDL1 apoB and TG production rates were significantly decreased, whereas VLDL2 apoB and TG production rates remained unchanged. TG catabolic rate was increased in both VLDL1 and VLDL2 fractions, but only the VLDL2 apoB catabolic rate tended to increase. Furthermore, post-surgery VLDL1 apoB and TG production rates, but not VLDL2, were positively correlated with insulin resistance. Insulin-mediated stimulation of peripheral lipoprotein lipolysis was also improved after the surgery. In summary, RYGB resulted in a reduced hepatic VLDL1 production that correlated with reduced insulin resistance, an elevated VLDL2 clearance, and improved insulin sensitivity in lipoprotein lipolysis pathways.
Authors
Vehpi Yildirim, Kasper W. ter Horst, Pim W. Gilijamse, Dewi van Harskamp, Henk Schierbeek, Hans Jansen, Alinda W.M. Schimmel, Max Nieuwdorp, Albert K. Groen, Mireille J. Serlie, Natal A.W. van Riel, Geesje M. Dallinga-Thie
Abstract
Proline and its synthesis enzyme pyrroline-5-carboxylate reductase 1 (PYCR1) are implicated in epithelial-mesenchymal transition (EMT), yet how proline and PYCR1 function in allergic asthmatic airway remodeling via EMT has not yet been addressed. In the present study, increased levels of plasma proline and PYCR1 were observed in asthmatic patients. Similarly, proline and PYCR1 in lung tissues were higher in a murine allergic asthma model induced by house dust mites (HDMs). Pycr1 knockout (KO) decreased proline in lung tissues, with reduced airway remodeling and EMT. Mechanistically, loss of Pycr1 restrained HDM-induced EMT by modulating mitochondrial fission, metabolic reprogramming, and the AKT/mTOR1 and WNT3a/β–catenin signaling pathways in airway epithelial cells. Therapeutic inhibition of PYCR1 in wild-type mice disrupted HDM-induced airway inflammation and remodeling. Deprivation of exogeneous proline partially relieved HDM-induced airway remodeling to some extent. Collectively, this study illuminates that proline and PYCR1 involved with airway remodeling in allergic asthma could be viable targets for asthma treatment.
Authors
Tingting Xu, Zhenzhen Wu, Qi Yuan, Xijie Zhang, Yanan Liu, Chaojie Wu, Meijuan Song, Jingjing Wu, Jingxian Jiang, Zhengxia Wang, Zhongqi Chen, Mingshun Zhang, Mao Huang, Ningfei Ji
Abstract
BACKGROUND Weight-loss diets often target dietary fat or carbohydrates, macronutrients that are sensed via distinct gut-brain pathways and differentially affect peripheral hormones and metabolism. However, the effects of such diet changes on the human brain are unclear. METHODS We investigated whether selective isocaloric reductions in dietary fat or carbohydrates altered dopamine D2/3 receptor binding potential (D2BP) and neural activity in brain-reward regions in response to visual food cues in 17 inpatient adults with obesity as compared with a eucaloric baseline diet using a randomized crossover design. RESULTS On the fifth day of dietary fat restriction, but not carbohydrate restriction, both D2BP and neural activity to food cues were decreased in brain-reward regions. After the reduced-fat diet, ad libitum intake shifted toward foods high in both fat and carbohydrates. CONCLUSION These results suggest that dietary fat restriction increases tonic dopamine in brain-reward regions and affects food choice in ways that may hamper diet adherence. TRIAL REGISTRATION ClinicalTrials.gov NCT00846040 FUNDING. NIDDK 1ZIADK013037.
Authors
Valerie L. Darcey, Juen Guo, Amber B. Courville, Isabelle Gallagher, Jason A. Avery, W. Kyle Simmons, John E. Ingeholm, Peter Herscovitch, Alex Martin, Kevin D. Hall
Abstract
The mineralocorticoid aldosterone, secreted by the adrenal zona glomerulosa (ZG), is critical for life, maintaining ion homeostasis and blood pressure. Therapeutic inhibition of protein phosphatase 3 (Calcineurin (Cn)) results in inappropriately low plasma aldosterone levels despite concomitant hyperkalemia and hyperreninemia. We tested the hypothesis that Cn participates in the signal transduction pathway regulating aldosterone synthesis. Inhibition of Cn with tacrolimus abolished the potassium (K+)-stimulated expression of aldosterone synthase, encoded by CYP11B2, in the NCI-H295R human adrenocortical cell line as well as ex vivo in mouse and human adrenal tissue. ZG-specific deletion of the regulatory Cn subunit CnB1 diminished Cyp11b2 expression in vivo and disrupted K+-mediated aldosterone synthesis. Phosphoproteomic analysis identified Nuclear factor of activated T-cells, cytoplasmic 4 (NFATc4) as a target for Cn-mediated dephosphorylation. Deletion of NFATc4 impaired K+-dependent stimulation of CYP11B2 expression and aldosterone production while expression of a constitutively active form of NFATc4 increased expression of CYP11B2 in NCI-H295R cells. Chromatin immunoprecipitation revealed NFATc4 directly regulates CYP11B2 expression. Thus, calcineurin controls aldosterone production via the Cn-NFATc4 pathway. Inhibition of Cn-NFATc4 signaling may explain low plasma aldosterone levels and hyperkalemia in patients treated with tacrolimus and the Cn-NFATc4 pathway may provide novel molecular targets to treat primary aldosteronism.
Authors
Mesut Berber, Sining Leng, Agnieszka Wengi, Denise V. Winter, Alex Odermatt, Felix Beuschlein, Johannes Loffing, David T. Breault, David Penton
Abstract
Insulin secretion from pancreatic β cells is essential to the maintenance of glucose homeostasis. Defects in this process result in diabetes. Identifying genetic regulators that impair insulin secretion is crucial for the identification of novel therapeutic targets. Here, we show that reduction of ZNF148 in human islets, and its deletion in stem cell–derived β cells (SC–β cells), enhances insulin secretion. Transcriptomics of ZNF148-deficient SC–β cells identifies increased expression of annexin and S100 genes whose proteins form tetrameric complexes involved in regulation of insulin vesicle trafficking and exocytosis. ZNF148 in SC–β cells prevents translocation of annexin A2 from the nucleus to its functional place at the cell membrane via direct repression of S100A16 expression. These findings point to ZNF148 as a regulator of annexin-S100 complexes in human β cells and suggest that suppression of ZNF148 may provide a novel therapeutic strategy to enhance insulin secretion.
Authors
Eleonora de Klerk, Yini Xiao, Christopher H. Emfinger, Mark P. Keller, David I. Berrios, Valentina Loconte, Axel A. Ekman, Kate L. White, Rebecca L. Cardone, Richard G. Kibbey, Alan D. Attie, Matthias Hebrok
Abstract
Fatty acid binding protein 4 (FABP4) is a lipid chaperone secreted from adipocytes upon stimulation of lipolysis. Circulating FABP4 levels strongly correlate with obesity and metabolic pathologies in experimental models and humans. While adipocytes have been presumed to be the major source of hormonal FABP4, this question has not been addressed definitively in vivo. We generated mice with Fabp4 deletion in cells known to express the gene; adipocytes (Adipo-KO), endothelial cells (Endo-KO), myeloid cells (Myeloid-KO), and the whole body (Total-KO) to examine the contribution of these cell types to basal and stimulated plasma FABP4 levels. Unexpectedly, baseline plasma FABP4 was not significantly reduced in Adipo-KO mice, whereas Endo-KO mice showed ~87% reduction versus wildtype controls. In contrast, Adipo-KO mice exhibited ~62% decreased induction of FABP4 responses to lipolysis, while Endo-KO mice showed only mildly decreased induction, indicating that adipocytes are the main source of increases in FABP4 during lipolysis. We did not detect any myeloid contribution to circulating FABP4. Surprisingly, despite the nearly intact induction of FABP4, Endo-KO mice showed blunted lipolysis-induced insulin secretion, identical to Total-KO mice. We conclude that the endothelium is the major source of baseline hormonal FABP4 and is required for the insulin response to lipolysis.
Authors
Karen E. Inouye, Kacey J. Prentice, Alexandra Lee, Zeqiu B. Wang, Carla Dominguez-Gonzalez, Mu Xian Chen, Jillian K. Riveros, M. Furkan Burak, Grace Y. Lee, Gokhan S. Hotamisligil
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