Publications by authors named "Stacy G Wendell"

27 Publications

  • Page 1 of 1

Lactate oxidative phosphorylation by annulus fibrosus cells: evidence for lactate-dependent metabolic symbiosis in intervertebral discs.

Arthritis Res Ther 2021 May 21;23(1):145. Epub 2021 May 21.

Department of Orthopaedic Surgery, Ferguson Laboratory for Orthopedic and Spine Research, University of Pittsburgh, 200 Lothrop Street, E1644 Biomedical Science Tower, Pittsburgh, PA, 15261, USA.

Background: Intervertebral disc degeneration contributes to low back pain. The avascular intervertebral disc consists of a central hypoxic nucleus pulpous (NP) surrounded by the more oxygenated annulus fibrosus (AF). Lactic acid, an abundant end-product of NP glycolysis, has long been viewed as a harmful waste that acidifies disc tissue and decreases cell viability and function. As lactic acid is readily converted into lactate in disc tissue, the objective of this study was to determine whether lactate could be used by AF cells as a carbon source rather than being removed from disc tissue as a waste byproduct.

Methods: Import and conversion of lactate to tricarboxylic acid (TCA) cycle intermediates and amino acids in rabbit AF cells were measured by heavy-isotope (C-lactate) tracing experiments using mass spectrometry. Levels of protein expression of lactate converting enzymes, lactate importer and exporter in NP and AF tissues were quantified by Western blots. Effects of lactate on proteoglycan (S-sulfate) and collagen (H-proline) matrix protein synthesis and oxidative phosphorylation (Seahorse XFe96 Extracellular Flux Analyzer) in AF cells were assessed.

Results: Heavy-isotope tracing experiments revealed that AF cells imported and converted lactate into TCA cycle intermediates and amino acids using in vitro cell culture and in vivo models. Addition of exogenous lactate (4 mM) in culture media induced expression of the lactate importer MCT1 and increased oxygen consumption rate by 50%, mitochondrial ATP-linked respiration by 30%, and collagen synthesis by 50% in AF cell cultures grown under physiologic oxygen (2-5% O) and glucose concentration (1-5 mM). AF tissue highly expresses MCT1, LDH-H, an enzyme that preferentially converts lactate to pyruvate, and PDH, an enzyme that converts pyruvate to acetyl-coA. In contrast, NP tissue highly expresses MCT4, a lactate exporter, and LDH-M, an enzyme that preferentially converts pyruvate to lactate.

Conclusions: These findings support disc lactate-dependent metabolic symbiosis in which lactate produced by the hypoxic, glycolytic NP cells is utilized by the more oxygenated AF cells via oxidative phosphorylation for energy and matrix production, thus shifting the current research paradigm of viewing disc lactate as a waste product to considering it as an important biofuel. These scientifically impactful results suggest novel therapeutic targets in disc metabolism and degeneration.
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http://dx.doi.org/10.1186/s13075-021-02501-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8139157PMC
May 2021

Using lipid profiling to better characterize metabolic differences in apolipoprotein E (APOE) genotype among community-dwelling older Black men.

Geroscience 2021 May 15. Epub 2021 May 15.

Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 North Bellefield Avenue, Room 327, Pittsburgh, PA, 15213, USA.

Apolipoprotein E (APOE) allelic variation is associated with differences in overall circulating lipids and risks of major health outcomes. Lipid profiling provides the opportunity for a more detailed description of lipids that differ by APOE, to potentially inform therapeutic targets for mitigating higher morbidity and mortality associated with certain APOE genotypes. Here, we sought to identify lipids, lipid-like molecules, and important mediators of fatty acid metabolism that differ by APOE among 278 Black men ages 70-81. Using liquid chromatography-mass spectrometry methods, 222 plasma metabolites classified as lipids, lipid-like molecules, or essential in fatty acid metabolism were detected. We applied principal factor analyses to calculate a factor score for each main lipid category. APOE was categorized as ε4 carriers (n = 83; ε3ε4 or ε4ε4), ε2 carriers (n = 58; ε2ε3 or ε2ε2), or ε3 homozygotes (n = 137; ε3ε3). Using analysis of variance, the monoacylglycerol factor, cholesterol ester factor, the factor for triacylglycerols that consist mostly of polyunsaturated fatty acids, sphingosine, and free carnitine significantly differed by APOE (p < 0.05, false discovery rate < 0.30). The monoacylglycerol factor, cholesterol ester factor, and sphingosine were lower, whereas the factor for triacylglycerols that consisted mostly of polyunsaturated fatty acids was higher among ε2 carriers than remaining participants. Free carnitine was lower among ε4 carriers than ε3 homozygotes. Lower monoacylglycerols and cholesteryl esters and higher triacylglycerols that consist mostly of polyunsaturated fatty acids may be protective metabolic characteristics of APOE ε2 carriers, whereas lower carnitine may reflect altered mitochondrial functioning among ε4 carriers in this cohort of older Black men.
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http://dx.doi.org/10.1007/s11357-021-00382-6DOI Listing
May 2021

Sustained Dysbiosis and Decreased Fecal Short-Chain Fatty Acids after Traumatic Brain Injury and Impact on Neurologic Outcome.

J Neurotrauma 2021 Jun 7. Epub 2021 Jun 7.

Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

Traumatic brain injury (TBI) alters microbial populations present in the gut, which may impact healing and tissue recovery. However, the duration and impact of these changes on outcome from TBI are unknown. Short-chain fatty acids (SCFAs), produced by bacterial fermentation of dietary fiber, are important signaling molecules in the microbiota gut-brain axis. We hypothesized that TBI would lead to a sustained reduction in SCFA producing bacteria, fecal SCFAs concentration, and administration of soluble SCFAs would improve functional outcome after TBI. Adult mice ( = 10) had the controlled cortical impact (CCI) model of TBI performed (6 m/sec, 2-mm depth, 50-msec dwell). Stool samples were collected serially until 28 days after CCI and analyzed for SCFA concentration by high-performance liquid chromatography-mass spectrometry/mass spectrometry and microbiome analyzed by 16S gene sequencing. In a separate experiment, mice ( = 10/group) were randomized 2 weeks before CCI to standard drinking water or water supplemented with the SCFAs acetate (67.5 mM), propionate (25.9 mM), and butyrate (40 mM). Morris water maze performance was assessed on post-injury Days 14-19. Alpha diversity remained stable until 72 h, at which point a decline in diversity was observed without recovery out to 28 days. The taxonomic composition of post-TBI fecal samples demonstrated depletion of bacteria from , , and families, and enrichment of bacteria from the family. Analysis from paired fecal samples revealed a reduction in total SCFAs at 24 h and 28 days after TBI. Acetate, the most abundant SCFA detected in the fecal samples, was reduced at 7 days and 28 days after TBI. SCFA administration improved spatial learning after TBI versus standard drinking water. In conclusion, TBI is associated with reduced richness and diversity of commensal microbiota in the gut and a reduction in SCFAs detected in stool. Supplementation of soluble SCFAs improves spatial learning after TBI.
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http://dx.doi.org/10.1089/neu.2020.7506DOI Listing
June 2021

Metabolic support of tumour-infiltrating regulatory T cells by lactic acid.

Nature 2021 Mar 15;591(7851):645-651. Epub 2021 Feb 15.

Department of Immunology, University of Pittsburgh, Pittsburgh, PA, USA.

Regulatory T (T) cells, although vital for immune homeostasis, also represent a major barrier to anti-cancer immunity, as the tumour microenvironment (TME) promotes the recruitment, differentiation and activity of these cells. Tumour cells show deregulated metabolism, leading to a metabolite-depleted, hypoxic and acidic TME, which places infiltrating effector T cells in competition with the tumour for metabolites and impairs their function. At the same time, T cells maintain a strong suppression of effector T cells within the TME. As previous studies suggested that T cells possess a distinct metabolic profile from effector T cells, we hypothesized that the altered metabolic landscape of the TME and increased activity of intratumoral T cells are linked. Here we show that T cells display broad heterogeneity in their metabolism of glucose within normal and transformed tissues, and can engage an alternative metabolic pathway to maintain suppressive function and proliferation. Glucose uptake correlates with poorer suppressive function and long-term instability, and high-glucose conditions impair the function and stability of T cells in vitro. T cells instead upregulate pathways involved in the metabolism of the glycolytic by-product lactic acid. T cells withstand high-lactate conditions, and treatment with lactate prevents the destabilizing effects of high-glucose conditions, generating intermediates necessary for proliferation. Deletion of MCT1-a lactate transporter-in T cells reveals that lactate uptake is dispensable for the function of peripheral T cells but required intratumorally, resulting in slowed tumour growth and an increased response to immunotherapy. Thus, T cells are metabolically flexible: they can use 'alternative' metabolites in the TME to maintain their suppressive identity. Further, our results suggest that tumours avoid destruction by not only depriving effector T cells of nutrients, but also metabolically supporting regulatory populations.
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http://dx.doi.org/10.1038/s41586-020-03045-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7990682PMC
March 2021

Acetylation-mediated remodeling of the nucleolus regulates cellular acetyl-CoA responses.

PLoS Biol 2020 11 30;18(11):e3000981. Epub 2020 Nov 30.

Aging Institute, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

The metabolite acetyl-coenzyme A (acetyl-CoA) serves as an essential element for a wide range of cellular functions including adenosine triphosphate (ATP) production, lipid synthesis, and protein acetylation. Intracellular acetyl-CoA concentrations are associated with nutrient availability, but the mechanisms by which a cell responds to fluctuations in acetyl-CoA levels remain elusive. Here, we generate a cell system to selectively manipulate the nucleo-cytoplasmic levels of acetyl-CoA using clustered regularly interspaced short palindromic repeat (CRISPR)-mediated gene editing and acetate supplementation of the culture media. Using this system and quantitative omics analyses, we demonstrate that acetyl-CoA depletion alters the integrity of the nucleolus, impairing ribosomal RNA synthesis and evoking the ribosomal protein-dependent activation of p53. This nucleolar remodeling appears to be mediated through the class IIa histone deacetylases (HDACs). Our findings highlight acetylation-mediated control of the nucleolus as an important hub linking acetyl-CoA fluctuations to cellular stress responses.
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http://dx.doi.org/10.1371/journal.pbio.3000981DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7728262PMC
November 2020

A novel metabolic function of Myc in regulation of fatty acid synthesis in prostate cancer.

Oncogene 2021 Jan 16;40(3):592-602. Epub 2020 Nov 16.

Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.

A subset of human prostate cancer exhibits increased de novo synthesis of fatty acids, but the molecular driver(s) of this metabolic abnormality remains obscure. This study demonstrates a novel metabolic function of c-Myc (Myc) in regulation of fatty acid synthesis. The role of Myc in regulation of fatty acid synthesis was investigated by: (a) interrogation of the prostate cancer The Cancer Genome Atlas (TCGA) dataset, (b) chromatin immunoprecipitation, and (c) determination of the expression of fatty acid synthesis enzymes and targeted metabolomics using a mouse model and human specimens. The expression of MYC was positively associated with that of key fatty acid synthesis genes including ACLY, ACC1, and FASN in prostate cancer TCGA dataset. Chromatin immunoprecipitation revealed Myc occupancy at the promoters of ACLY, ACC1, and FASN. Prostate-specific overexpression of Myc in Hi-Myc transgenic mice resulted in overexpression of ACLY, ACC1, and FASN proteins in neoplastic lesions and increased circulating levels of total free fatty acids. Targeted metabolomics confirmed increased circulating levels of individual fatty acids in the plasma of Hi-Myc mice and human subjects when compared to corresponding controls. Immunohistochemistry also revealed a positive and statistically significant association in expression of Myc with that of ACC1 in human prostate adenocarcinoma specimens. We propose that Myc-regulated fatty acid synthesis is a valid target for therapy and/or prevention of prostate cancer.
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http://dx.doi.org/10.1038/s41388-020-01553-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7855479PMC
January 2021

Electrophile Modulation of Inflammation: A Two-Hit Approach.

Metabolites 2020 Nov 10;10(11). Epub 2020 Nov 10.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA.

Electrophilic small molecules have gained significant attention over the last decade in the field of covalent drug discovery. Long recognized as mediators of the inflammatory process, recent evidence suggests that electrophiles may modulate the immune response through the regulation of metabolic networks. These molecules function as pleiotropic signaling mediators capable of reversibly reacting with nucleophilic biomolecules, most notably at reactive cysteines. More specifically, electrophiles target critical cysteines in redox regulatory proteins to activate protective pathways such as the nuclear factor erythroid 2-related factor 2-Kelch-like ECH-associated protein 1 (Nrf2-Keap1) antioxidant signaling pathway while also inhibiting Nuclear Factor κB (NF-κB). During inflammatory states, reactive species broadly alter cell signaling through the oxidation of lipids, amino acids, and nucleic acids, effectively propagating the inflammatory sequence. Subsequent changes in metabolic signaling inform immune cell maturation and effector function. Therapeutic strategies targeting inflammatory pathologies leverage electrophilic drug compounds, in part, because of their documented effect on the redox balance of the cell. With mounting evidence demonstrating the link between redox signaling and metabolism, electrophiles represent ideal therapeutic candidates for the treatment of inflammatory conditions. Through their pleiotropic signaling activity, electrophiles may be used strategically to both directly and indirectly target immune cell metabolism.
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http://dx.doi.org/10.3390/metabo10110453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696920PMC
November 2020

Sulforaphane Diminishes the Formation of Mammary Tumors in Rats Exposed to 17β-Estradiol.

Nutrients 2020 Jul 30;12(8). Epub 2020 Jul 30.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA.

Elevated levels of estrogen are a risk factor for breast cancer. In addition to inducing DNA damage, estrogens can enhance cell proliferation as well as modulate fatty acid metabolism that collectively contributes to mammary tumorigenesis. Sulforaphane (SFN) is an isothiocyanate derived from broccoli that is currently under evaluation in multiple clinical trials for prevention of several diseases, including cancer. Previous studies showed that SFN suppressed DNA damage and lipogenesis pathways. Therefore, we hypothesized that administering SFN to animals that are co-exposed to 17β-estradiol (E2) would prevent mammary tumor formation. In our study, 4-6 week old female August Copenhagen Irish rats were implanted with slow-release E2 pellets (3 mg x 3 times) and gavaged 3x/week with either vehicle or 100 μmol/kg SFN for 56 weeks. SFN-treated rats were protected significantly against mammary tumor formation compared to vehicle controls. Mammary glands of SFN-treated rats showed decreased DNA damage while serum free fatty acids and triglyceride species were 1.5 to 2-fold lower in SFN-treated rats. Further characterization also showed that SFN diminished expression of enzymes involved in mammary gland lipogenesis. This study indicated that SFN protects against breast cancer development through multiple potential mechanisms in a clinically relevant hormonal carcinogenesis model.
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http://dx.doi.org/10.3390/nu12082282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468750PMC
July 2020

Graft IL-33 regulates infiltrating macrophages to protect against chronic rejection.

J Clin Invest 2020 10;130(10):5397-5412

Department of Surgery and.

Alarmins, sequestered self-molecules containing damage-associated molecular patterns, are released during tissue injury to drive innate immune cell proinflammatory responses. Whether endogenous negative regulators controlling early immune responses are also released at the site of injury is poorly understood. Herein, we establish that the stromal cell-derived alarmin interleukin 33 (IL-33) is a local factor that directly restricts the proinflammatory capacity of graft-infiltrating macrophages early after transplantation. By assessing heart transplant recipient samples and using a mouse heart transplant model, we establish that IL-33 is upregulated in allografts to limit chronic rejection. Mouse cardiac transplants lacking IL-33 displayed dramatically accelerated vascular occlusion and subsequent fibrosis, which was not due to altered systemic immune responses. Instead, a lack of graft IL-33 caused local augmentation of proinflammatory iNOS+ macrophages that accelerated graft loss. IL-33 facilitated a metabolic program in macrophages associated with reparative and regulatory functions, and local delivery of IL-33 prevented the chronic rejection of IL-33-deficient cardiac transplants. Therefore, IL-33 represents what we believe is a novel regulatory alarmin in transplantation that limits chronic rejection by restraining the local activation of proinflammatory macrophages. The local delivery of IL-33 in extracellular matrix-based materials may be a promising biologic for chronic rejection prophylaxis.
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http://dx.doi.org/10.1172/JCI133008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7524467PMC
October 2020

A Metabolite Composite Score Attenuated a Substantial Portion of the Higher Mortality Risk Associated With Frailty Among Community-Dwelling Older Adults.

J Gerontol A Biol Sci Med Sci 2021 Jan;76(2):378-384

Department of Epidemiology, University of Pittsburgh, Pennsylvania.

Background: Frailty is more prevalent among black versus white older Americans. We previously identified 37 metabolites associated with the vigor to frailty spectrum using the Scale of Aging Vigor in Epidemiology (SAVE) among older black men from the Health, Aging, and Body Composition (Health ABC) study. Here, we sought to develop a metabolite composite score based on the 37 SAVE-associated metabolites and determine whether the composite score predicts mortality and whether it attenuates the association between frailty and mortality among older black men.

Methods: Plasma metabolites were measured using liquid chromatography-mass spectrometry. Most of the 37 metabolites were organic acids/derivatives or lipids. Metabolites were ranked into tertiles: tertiles associated with more vigorous SAVE scores were scored 0, mid-tertiles were scored 1, and tertiles associated with frailer SAVE scores were scored 2. Composite scores were the sum of metabolite tertile scores. We examined mortality associations using Cox regression. Percent attenuation estimated the extent to which metabolites attenuated the association between frailty and mortality.

Results: One standard deviation frailer SAVE was associated with 30% higher mortality, adjusting for age and site (p = .0002); this association was attenuated by 56% after additionally adjusting for the metabolite composite score. In this model, one standard deviation higher metabolite composite score was associated with 46% higher mortality (p < .0001). Metabolite composite scores also predicted mortality (p = .045) in a validation sample of 120 older adults (40% men, 90% white).

Conclusion: These metabolites may provide a deeper characterization of the higher mortality that is associated with frailty among older adults.
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http://dx.doi.org/10.1093/gerona/glaa112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7812434PMC
January 2021

Germinal center B cells selectively oxidize fatty acids for energy while conducting minimal glycolysis.

Nat Immunol 2020 03 17;21(3):331-342. Epub 2020 Feb 17.

Department of Immunology, University of Pittsburgh, Pittsburgh, PA, USA.

Germinal center B cells (GCBCs) are critical for generating long-lived humoral immunity. How GCBCs meet the energetic challenge of rapid proliferation is poorly understood. Dividing lymphocytes typically rely on aerobic glycolysis over oxidative phosphorylation for energy. Here we report that GCBCs are exceptional among proliferating B and T cells, as they actively oxidize fatty acids (FAs) and conduct minimal glycolysis. In vitro, GCBCs had a very low glycolytic extracellular acidification rate but consumed oxygen in response to FAs. [C]-glucose feeding revealed that GCBCs generate significantly less phosphorylated glucose and little lactate. Further, GCBCs did not metabolize glucose into tricarboxylic acid (TCA) cycle intermediates. Conversely, [C]-palmitic acid labeling demonstrated that GCBCs generate most of their acetyl-CoA and acetylcarnitine from FAs. FA oxidation was functionally important, as drug-mediated and genetic dampening of FA oxidation resulted in a selective reduction of GCBCs. Hence, GCBCs appear to uncouple rapid proliferation from aerobic glycolysis.
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http://dx.doi.org/10.1038/s41590-020-0598-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7112716PMC
March 2020

Metabolites Associated with Walking Ability Among the Oldest Old from the CHS All Stars Study.

J Gerontol A Biol Sci Med Sci 2020 11;75(12):2371-2378

Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania.

Background: Low walking ability is highly prevalent with advancing age and predicts major health outcomes. Metabolomics may help to better characterize differences in walking ability among older adults, providing insight into potentially altered molecular processes underlying age-related decline in functioning. We sought to identify metabolites and metabolic pathways associated with high versus low walking ability among 120 participants ages 79-95 from the CHS All Stars study.

Methods: Using a nested case-control design, 60 randomly selected participants with low walking ability were matched one-to-one on age, gender, race, and fasting time with 60 participants with high walking ability. High versus low walking ability was defined as being in the best versus worst tertiles for both gait speed (≥0.9 vs <0.7 m/s) and the Walking Ability Index (7-9 vs 0-1). Using liquid chromatography-mass spectrometry, 569 metabolites were identified in overnight-fasting plasma.

Results: Ninety-six metabolites were associated with walking ability, where 24% were triacylglycerols. Triacylglycerols that were higher among those with high walking ability consisted mostly of polyunsaturated fatty acids, whereas triacylglycerols that were lower among those with high walking ability consisted mostly of saturated or monounsaturated fatty acids. Body composition partly explained associations between some metabolites and walking ability. Proline and arginine metabolism was a top pathway associated with walking ability.

Conclusion: These results may partly reflect pathways of modifiable risk factors, including excess dietary lipids and lack of physical activity, contributing to obesity and further alterations in metabolic pathways that lead to age-related decline in walking ability in this older adult cohort.
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http://dx.doi.org/10.1093/gerona/glaa030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662173PMC
November 2020

Nrf2 activation protects against lithium-induced nephrogenic diabetes insipidus.

JCI Insight 2020 01 16;5(1). Epub 2020 Jan 16.

Department of Pharmacology and Chemical Biology.

Lithium (Li) is the mainstay pharmacotherapeutic mood stabilizer in bipolar disorder. Its efficacious use is complicated by acute and chronic renal side effects, including nephrogenic diabetes insipidus (NDI) and progression to chronic kidney disease (CKD). The nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway senses and coordinates cellular responses to oxidative and electrophilic stress. Here, we identify that graded genetic activation of Nrf2 protects against Li-induced NDI (Li-NDI) and volume wasting via an aquaporin 2-independent mechanism. Renal Nrf2 activity is differentially expressed on functional segments of the nephron, and its activation along the distal tubule and collecting duct directly modulates ion transporter expression, mimicking paradoxical effects of diuretics in mitigating Li-NDI. In addition, Nrf2 reduces cyclooxygenase expression and vasoactive prostaglandin biosynthesis. Pharmacologic activation of Nrf2 confers protective effects, confirming this pathway as a potentially novel druggable target for the prevention of acute and chronic renal sequelae of Li therapy.
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http://dx.doi.org/10.1172/jci.insight.128578DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7030822PMC
January 2020

Hepatic insulin sensitivity is improved in high-fat diet-fed Park2 knockout mice in association with increased hepatic AMPK activation and reduced steatosis.

Physiol Rep 2019 11;7(21):e14281

Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.

Park2 is an E3 ubiquitin ligase known for its role in mitochondrial quality control via the mitophagy pathway. Park2 KO mice are protected from diet-induced obesity and hepatic insulin sensitivity is improved in high-fat diet (HFD)-fed Park2 KO mice even under body weight-matched conditions. In order to better understand the cellular mechanism by which Park2 KO mice are protected from diet-induced hepatic insulin resistance, we determined changes in multiple pathways commonly associated with the pathogenesis of insulin resistance, namely levels of bioactive lipid species, activation of the endoplasmic reticulum (ER) stress response and changes in cytokine levels and signaling. We report for the first time that whole-body insulin sensitivity is unchanged in regular chow (RC)-fed Park2 KO mice, and that liver diacylglycerol levels are reduced and very-long-chain ceramides are increased in Park2 KO mice fed HFD for 1 week. Hepatic transcriptional markers of the ER stress response were reduced and plasma tumor necrosis factor-α (TNFα), interleukin-6 and -10 (IL6, IL10) were significantly increased in HFD-fed Park2 KO mice; however, there were no detectable differences in hepatic inflammatory signaling pathways between groups. Interestingly, hepatic adenylate charge was reduced in HFD-fed Park2 KO liver and was associated increased activation of AMPK. These data suggest that negative energy balance that contributed to protection from obesity during chronic HFD manifested at the level of the hepatocyte during short-term HFD feeding and contributed to the improved hepatic insulin sensitivity.
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http://dx.doi.org/10.14814/phy2.14281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6854109PMC
November 2019

Cutting Edge: TCR Signal Strength Regulates Acetyl-CoA Metabolism via AKT.

J Immunol 2019 12 18;203(11):2771-2775. Epub 2019 Oct 18.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261.

TCR signaling activates kinases including AKT/mTOR that engage metabolic networks to support the energetic demands of a T cell during an immune response. It is realized that CD4 T cell subsets have different metabolic requirements. Yet, how TCR signaling is coupled to the regulation of intermediate metabolites and how changes in metabolite flux contribute to T cell differentiation are less established. We find that TCR signaling regulates acetyl-CoA metabolism via AKT in murine CD4 T cells. Weak TCR signals promote AKT-catalyzed phosphorylation and inhibition of citrate synthase, elevated acetyl-CoA levels, and hyperacetylation of mitochondrial proteins. Genetic knockdown of citrate synthase promotes increased nuclear acetyl-CoA levels, increased histone acetylation at the FOXP3 promotor and induction of FOXP3 transcription. These data identify a circuit between AKT signaling and acetyl-CoA metabolism regulated via TCR signal strength and that transient fluctuations in acetyl-CoA levels function in T cell fate decisions.
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http://dx.doi.org/10.4049/jimmunol.1900749DOI Listing
December 2019

Synthesis of an Electrophilic Keto-Tetraene 15-oxo-Lipoxin A Methyl Ester a MIDA Boronate.

Tetrahedron Lett 2018 Sep 10;59(39):3524-3527. Epub 2018 Aug 10.

Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA USA 16260.

15-oxo-Lipoxin A (15-oxo- LXA) has been identified as a natural metabolite of the fatty acid signaling mediator Lipoxin A. Herein, we report a total synthesis of the methyl ester of 15-oxo-LXA to be used in investigations of potential electrophilic bioactivity of this metabolite. The methyl ester of 15-oxo-LXA was synthesized in a convergent 15 step (9 steps longest linear) sequence starting from 1-octyn-3-ol and 2-deoxy-D-ribose with Sonogashira and Suzuki cross-couplings of a MIDA boronate as key steps.
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http://dx.doi.org/10.1016/j.tetlet.2018.08.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6677397PMC
September 2018

Treg Cells Promote the SREBP1-Dependent Metabolic Fitness of Tumor-Promoting Macrophages via Repression of CD8 T Cell-Derived Interferon-γ.

Immunity 2019 08 23;51(2):381-397.e6. Epub 2019 Jul 23.

Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Tumor Microenvironment Center, UPMC Hillman Cancer Center, Pittsburgh, PA 15232, USA. Electronic address:

Regulatory T (Treg) cells are crucial for immune homeostasis, but they also contribute to tumor immune evasion by promoting a suppressive tumor microenvironment (TME). Mice with Treg cell-restricted Neuropilin-1 deficiency show tumor resistance while maintaining peripheral immune homeostasis, thereby providing a controlled system to interrogate the impact of intratumoral Treg cells on the TME. Using this and other genetic models, we showed that Treg cells shaped the transcriptional landscape across multiple tumor-infiltrating immune cell types. Treg cells suppressed CD8 T cell secretion of interferon-γ (IFNγ), which would otherwise block the activation of sterol regulatory element-binding protein 1 (SREBP1)-mediated fatty acid synthesis in immunosuppressive (M2-like) tumor-associated macrophages (TAMs). Thus, Treg cells indirectly but selectively sustained M2-like TAM metabolic fitness, mitochondrial integrity, and survival. SREBP1 inhibition augmented the efficacy of immune checkpoint blockade, suggesting that targeting Treg cells or their modulation of lipid metabolism in M2-like TAMs could improve cancer immunotherapy.
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http://dx.doi.org/10.1016/j.immuni.2019.06.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703933PMC
August 2019

Metabolites Associated with Vigor to Frailty Among Community-Dwelling Older Black Men.

Metabolites 2019 Apr 30;9(5). Epub 2019 Apr 30.

Department of Epidemiology, University of Pittsburgh, Pittsburgh, PA 15213, USA.

Black versus white older Americans are more likely to experience frailty, a condition associated with adverse health outcomes. To reduce racial disparities in health, a complete understanding of the pathophysiology of frailty is needed. Metabolomics may further our understanding by characterizing differences in the body during a vigorous versus frail state. We sought to identify metabolites and biological pathways associated with vigor to frailty among 287 black men ages 70-81 from the Health, Aging, and Body Composition study. Using liquid chromatography-mass spectrometry, 350 metabolites were measured in overnight-fasting plasma. The Scale of Aging Vigor in Epidemiology (SAVE) measured vigor to frailty based on weight change, strength, energy, gait speed, and physical activity. Thirty-seven metabolites correlated with SAVE scores ( < 0.05), while adjusting for age and site. Fourteen metabolites remained significant after multiple comparisons adjustment (false discovery rate < 0.30). Lower values of tryptophan, methionine, tyrosine, asparagine, C14:0 sphingomyelin, and 1-methylnicotinamide, and higher values of glucoronate, N-carbamoyl-beta-alanine, isocitrate, creatinine, C4-OH carnitine, cystathionine, hydroxyphenylacetate, and putrescine were associated with frailer SAVE scores. Pathway analyses identified nitrogen metabolism, aminoacyl-tRNA biosynthesis, and the citric acid cycle. Future studies need to confirm these SAVE-associated metabolites and pathways that may indicate novel mechanisms involved in the frailty syndrome.
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http://dx.doi.org/10.3390/metabo9050083DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572139PMC
April 2019

Adropin treatment restores cardiac glucose oxidation in pre-diabetic obese mice.

J Mol Cell Cardiol 2019 04 26;129:174-178. Epub 2019 Feb 26.

Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA; Center for Metabolism and Mitochondrial Medicine, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Exposure to a high fat (HF) diet promotes increased fatty acid uptake, fatty acid oxidation and lipid accumulation in the heart. These maladaptive changes impact cellular energy metabolism and may promote the development of cardiac dysfunction. Attempts to increase cardiac glucose utilization have been proposed as a way to reverse cardiomyopathy in obese and diabetic individuals. Adropin is a nutrient-regulated metabolic hormone shown to promote glucose oxidation over fatty acid oxidation in skeletal muscle homogenates in vitro. The focus of the current study was to investigate whether adropin can regulate substrate metabolism in the heart following prolonged exposure to a HF diet in vivo. Mice on a long-term HF diet received serial intraperitoneal injections of vehicle or adropin over three days. Cardiac glucose oxidation was significantly reduced in HF animals, which was rescued by acute adropin treatment. Significant decreases in cardiac pyruvate dehydrogenase activity were observed in HF animals, which were also reversed by adropin treatment. In contrast to previous studies, this change was unrelated to Pdk4 expression, which remained elevated in both vehicle- and adropin-treated HF mice. Instead, we show that adropin modulated the expression of the mitochondrial acetyltransferase enzyme GCN5L1, which altered the acetylation status and activity of fuel metabolism enzymes to favor glucose utilization. Our findings indicate that adropin exposure leads to increased cardiac glucose oxidation under HF conditions, and may provide a future therapeutic avenue in the treatment of diabetic cardiomyopathy.
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http://dx.doi.org/10.1016/j.yjmcc.2019.02.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486841PMC
April 2019

BOLA (BolA Family Member 3) Deficiency Controls Endothelial Metabolism and Glycine Homeostasis in Pulmonary Hypertension.

Circulation 2019 05;139(19):2238-2255

Program in Translational Lung Research, University of Colorado Denver, Aurora, CO (R.K., B.B.G.).

Background: Deficiencies of iron-sulfur (Fe-S) clusters, metal complexes that control redox state and mitochondrial metabolism, have been linked to pulmonary hypertension (PH), a deadly vascular disease with poorly defined molecular origins. BOLA3 (BolA Family Member 3) regulates Fe-S biogenesis, and mutations in BOLA3 result in multiple mitochondrial dysfunction syndrome, a fatal disorder associated with PH. The mechanistic role of BOLA3 in PH remains undefined.

Methods: In vitro assessment of BOLA3 regulation and gain- and loss-of-function assays were performed in human pulmonary artery endothelial cells using siRNA and lentiviral vectors expressing the mitochondrial isoform of BOLA3. Polymeric nanoparticle 7C1 was used for lung endothelium-specific delivery of BOLA3 siRNA oligonucleotides in mice. Overexpression of pulmonary vascular BOLA3 was performed by orotracheal transgene delivery of adeno-associated virus in mouse models of PH.

Results: In cultured hypoxic pulmonary artery endothelial cells, lung from human patients with Group 1 and 3 PH, and multiple rodent models of PH, endothelial BOLA3 expression was downregulated, which involved hypoxia inducible factor-2α-dependent transcriptional repression via histone deacetylase 1-mediated histone deacetylation. In vitro gain- and loss-of-function studies demonstrated that BOLA3 regulated Fe-S integrity, thus modulating lipoate-containing 2-oxoacid dehydrogenases with consequent control over glycolysis and mitochondrial respiration. In contexts of siRNA knockdown and naturally occurring human genetic mutation, cellular BOLA3 deficiency downregulated the glycine cleavage system protein H, thus bolstering intracellular glycine content. In the setting of these alterations of oxidative metabolism and glycine levels, BOLA3 deficiency increased endothelial proliferation, survival, and vasoconstriction while decreasing angiogenic potential. In vivo, pharmacological knockdown of endothelial BOLA3 and targeted overexpression of BOLA3 in mice demonstrated that BOLA3 deficiency promotes histological and hemodynamic manifestations of PH. Notably, the therapeutic effects of BOLA3 expression were reversed by exogenous glycine supplementation.

Conclusions: BOLA3 acts as a crucial lynchpin connecting Fe-S-dependent oxidative respiration and glycine homeostasis with endothelial metabolic reprogramming critical to PH pathogenesis. These results provide a molecular explanation for the clinical associations linking PH with hyperglycinemic syndromes and mitochondrial disorders. These findings also identify novel metabolic targets, including those involved in epigenetics, Fe-S biogenesis, and glycine biology, for diagnostic and therapeutic development.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.035889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6519484PMC
May 2019

Pilot Study of the Effect of Plant-Based Enteral Nutrition on the Gut Microbiota in Chronically Ill Tube-Fed Children.

JPEN J Parenter Enteral Nutr 2019 09 15;43(7):899-911. Epub 2019 Jan 15.

Department of Surgery, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.

Background: Dietary intake sharply impacts the structure and function of the gut microbiota, which is important for childhood health. However, little is known about the microbiota of children who cannot eat by mouth. Standard enteral formulas for supplemental nutrition are low in fiber and high in processed sugars and are commonly associated with gastrointestinal side effects. In this pilot study, we examined the effects of plant-based enteral nutrition (PBEN) upon the gut bacteria of chronically ill children.

Methods: Ten children (median age 3.5 years, age range 2-8 years) dependent upon conventional enteral formula were transitioned to PBEN for 2 months. Microbial diversity within fecal samples collected before and after PBEN was assessed by 16S ribosomal RNA gene sequence analysis and was compared with rectal swabs from healthy children. Fecal short-chain fatty acids and bile acids were measured in parallel.

Results: Relative to control samples, fecal samples from study subjects were depleted of commensals (eg, Faecalibacterium) and enriched with pathogens (eg, Enterococcus). Postintervention samples from study subjects were more similar to healthy controls. Most subjects experienced PBEN-induced alterations in the gut microbiota, but these changes varied significantly across individuals. Clinical diaries indicated that PBEN was well tolerated, with improvement in symptoms noted in several subjects.

Conclusion: Results from this pilot study suggest that PBEN is well tolerated and could improve the health of the microbiota in chronically ill children. This trial provides a rationale for systematic evaluation of PBEN in clinical trials of children who require supplemental nutrition.
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http://dx.doi.org/10.1002/jpen.1504DOI Listing
September 2019

Evaluation of 2-Thiothiazolidine-4-Carboxylic Acid, a Common Metabolite of Isothiocyanates, as a Potential Biomarker of Cruciferous Vegetable Intake.

Mol Nutr Food Res 2019 02 22;63(3):e1801029. Epub 2018 Nov 22.

Department of Pharmacology & Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, 15261, USA.

Scope: Cruciferous vegetable consumption is associated with favorable health outcomes. Bioactive compounds arising in these, especially isothiocyanates, exert effects that contribute to prevention of disease, in large part through the attenuation of inflammation and oxidative stress. However, much about isothiocyanate metabolites and their role as biomarkers of crucifer intake remain unknown.

Methods And Results: The utility and limitations of 2-thiothiazolidine-4-carboxylic acid (TTCA) as a urinary biomarker of broccoli beverage intake are tested in a randomized crossover clinical trial where 50 participants consumed either a glucoraphanin-rich (GRR) or sulforaphane-rich (SFR) beverage. Compared to run-in and wash-out periods, significantly higher urinary TTCA is observed after broccoli beverage consumption. Measurements also show that TTCA is present in beverage powders and in all tested cruciferous vegetables. GRR results in excretion of ≈87% of the ingested TTCA while SFR results in excretion of ≈176%. Elevated urinary TTCA is observed in rats administered 100 µmol kg SFN. Unlike SFN, TTCA does not activate Nrf2-mediated cytoprotective signaling.

Conclusion: Collectively, TTCA appears to be a common isothiocyanate-derived metabolite that has the capacity to be utilized as a biomarker of cruciferous vegetables that would be beneficial for objective and quantitative tracking of intake in studies.
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http://dx.doi.org/10.1002/mnfr.201801029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6488352PMC
February 2019

Key regulators of lipid metabolism drive endocrine resistance in invasive lobular breast cancer.

Breast Cancer Res 2018 09 4;20(1):106. Epub 2018 Sep 4.

Women's Cancer Research Center, UPMC Hillman Cancer Institute, Magee Womens Research Institute, 204 Craft Avenue, Pittsburgh, PA, 15213, USA.

Background: Invasive lobular breast carcinoma (ILC) is a histological subtype of breast cancer that is characterized by loss of E-cadherin and high expression of estrogen receptor alpha (ERα). In many cases, ILC is effectively treated with adjuvant aromatase inhibitors (AIs); however, acquired AI resistance remains a significant problem.

Methods: To identify underlying mechanisms of acquired anti-estrogen resistance in ILC, we recently developed six long-term estrogen-deprived (LTED) variant cell lines from the human ILC cell lines SUM44PE (SUM44; two lines) and MDA-MB-134VI (MM134; four lines). To better understand mechanisms of AI resistance in these models, we performed transcriptional profiling analysis by RNA-sequencing followed by candidate gene expression and functional studies.

Results: MM134 LTED cells expressed ER at a decreased level and lost growth response to estradiol, while SUM44 LTED cells retained partial ER activity. Our transcriptional profiling analysis identified shared activation of lipid metabolism across all six independent models. However, the underlying basis of this signature was distinct between models. Oxysterols were able to promote the proliferation of SUM44 LTED cells but not MM134 LTED cells. In contrast, MM134 LTED cells displayed a high expression of the sterol regulatory element-binding protein 1 (SREBP1), a regulator of fatty acid and cholesterol synthesis, and were hypersensitive to genetic or pharmacological inhibition of SREBPs. Several SREBP1 downstream targets involved in fatty acid synthesis, including FASN, were induced, and MM134 LTED cells were more sensitive to etomoxir, an inhibitor of the rate-limiting enzyme in beta-oxidation, than their respective parental control cells. Finally, in silico expression analysis in clinical specimens from a neo-adjuvant endocrine trial showed a significant association between the increase of SREBP1 expression and lack of clinical response, providing further support for a role of SREBP1 in the acquisition of endocrine resistance in breast cancer.

Conclusions: Our characterization of a unique series of AI-resistant ILC models identifies the activation of key regulators of fatty acid and cholesterol metabolism, implicating lipid-metabolic processes driving estrogen-independent growth of ILC cells. Targeting these changes may prove a strategy for prevention and treatment of endocrine resistance for patients with ILC.
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http://dx.doi.org/10.1186/s13058-018-1041-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6124012PMC
September 2018

CMPF, a Metabolite Formed Upon Prescription Omega-3-Acid Ethyl Ester Supplementation, Prevents and Reverses Steatosis.

EBioMedicine 2018 Jan 19;27:200-213. Epub 2017 Dec 19.

Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada. Electronic address:

Prescription ω-3 fatty acid ethyl ester supplements are commonly used for the treatment of hypertriglyceridemia. However, the metabolic profile and effect of the metabolites formed by these treatments remain unknown. Here we utilized unbiased metabolomics to identify 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) as a significant metabolite of the ω-3-acid ethyl ester prescription Lovaza™ in humans. Administration of CMPF to mice before or after high-fat diet feeding at exposures equivalent to those observed in humans increased whole-body lipid metabolism, improved insulin sensitivity, increased beta-oxidation, reduced lipogenic gene expression, and ameliorated steatosis. Mechanistically, we find that CMPF acutely inhibits ACC activity, and induces long-term loss of SREBP1c and ACC1/2 expression. This corresponds to an induction of FGF21, which is required for long-term steatosis protection, as FGF21KO mice are refractory to the improved metabolic effects. Thus, CMPF treatment in mice parallels the effects of human Lovaza™ supplementation, revealing that CMPF may contribute to the improved metabolic effects observed with ω-3 fatty acid prescriptions.
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http://dx.doi.org/10.1016/j.ebiom.2017.12.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5828468PMC
January 2018

Nitro-fatty acid inhibition of triple-negative breast cancer cell viability, migration, invasion, and tumor growth.

J Biol Chem 2018 01 20;293(4):1120-1137. Epub 2017 Nov 20.

From the Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260,

Triple-negative breast cancer (TNBC) comprises ∼20% of all breast cancers and is the most aggressive mammary cancer subtype. Devoid of the estrogen and progesterone receptors, along with the receptor tyrosine kinase ERB2 (HER2), that define most mammary cancers, there are no targeted therapies for patients with TNBC. This, combined with a high metastatic rate and a lower 5-year survival rate than for other breast cancer phenotypes, means there is significant unmet need for new therapeutic strategies. Herein, the anti-neoplastic effects of the electrophilic fatty acid nitroalkene derivative, 10-nitro-octadec-9-enoic acid (nitro-oleic acid, NO-OA), were investigated in multiple preclinical models of TNBC. NO-OA reduced TNBC cell growth and viability , attenuated TNFα-induced TNBC cell migration and invasion, and inhibited the tumor growth of MDA-MB-231 TNBC cell xenografts in the mammary fat pads of female nude mice. The up-regulation of these aggressive tumor cell growth, migration, and invasion phenotypes is mediated in part by the constitutive activation of pro-inflammatory nuclear factor κB (NF-κB) signaling in TNBC. NO-OA inhibited TNFα-induced NF-κB transcriptional activity in human TNBC cells and suppressed downstream NF-κB target gene expression, including the metastasis-related proteins intercellular adhesion molecule-1 and urokinase-type plasminogen activator. The mechanisms accounting for NF-κB signaling inhibition by NO-OA in TNBC cells were multifaceted, as NO-OA () inhibited the inhibitor of NF-κB subunit kinase β phosphorylation and downstream inhibitor of NF-κB degradation, () alkylated the NF-κB RelA protein to prevent DNA binding, and () promoted RelA polyubiquitination and proteasomal degradation. Comparisons with non-tumorigenic human breast epithelial MCF-10A and MCF7 cells revealed that NO-OA more selectively inhibited TNBC function. This was attributed to more facile mechanisms for maintaining redox homeostasis in normal breast epithelium, including a more favorable thiol/disulfide balance, greater extents of multidrug resistance protein-1 (MRP1) expression, and greater MRP1-mediated efflux of NO-OA-glutathione conjugates. These observations reveal that electrophilic fatty acid nitroalkenes react with more alkylation-sensitive targets in TNBC cells to inhibit growth and viability.
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http://dx.doi.org/10.1074/jbc.M117.814368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787792PMC
January 2018

Genetic Dissociation of Glycolysis and the TCA Cycle Affects Neither Normal nor Neoplastic Proliferation.

Cancer Res 2017 11 7;77(21):5795-5807. Epub 2017 Sep 7.

Division of Hematology/Oncology, Department of Pediatrics, Children's Hospital of Pittsburgh of The University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Rapidly proliferating cells increase glycolysis at the expense of oxidative phosphorylation (oxphos) to generate sufficient levels of glycolytic intermediates for use as anabolic substrates. The pyruvate dehydrogenase complex (PDC) is a critical mitochondrial enzyme that catalyzes pyruvate's conversion to acetyl coenzyme A (AcCoA), thereby connecting these two pathways in response to complex energetic, enzymatic, and metabolic cues. Here we utilized a mouse model of hepatocyte-specific PDC inactivation to determine the need for this metabolic link during normal hepatocyte regeneration and malignant transformation. In PDC "knockout" (KO) animals, the long-term regenerative potential of hepatocytes was unimpaired, and growth of aggressive experimental hepatoblastomas was only modestly slowed in the face of 80%-90% reductions in AcCoA and significant alterations in the levels of key tricarboxylic acid (TCA) cycle intermediates and amino acids. Overall, oxphos activity in KO livers and hepatoblastoma was comparable with that of control counterparts, with evidence that metabolic substrate abnormalities were compensated for by increased mitochondrial mass. These findings demonstrate that the biochemical link between glycolysis and the TCA cycle can be completely severed without affecting normal or neoplastic proliferation, even under the most demanding circumstances. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-1325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5668145PMC
November 2017

Opposing Effects of Cyclooxygenase-2 (COX-2) on Estrogen Receptor β (ERβ) Response to 5α-Reductase Inhibition in Prostate Epithelial Cells.

J Biol Chem 2016 Jul 13;291(28):14747-60. Epub 2016 May 13.

From the Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260,

Current pharmacotherapies for symptomatic benign prostatic hyperplasia (BPH), an androgen receptor-driven, inflammatory disorder affecting elderly men, include 5α-reductase (5AR) inhibitors (i.e. dutasteride and finasteride) to block the conversion of testosterone to the more potent androgen receptor ligand dihydrotestosterone. Because dihydrotestosterone is the precursor for estrogen receptor β (ERβ) ligands, 5AR inhibitors could potentially limit ERβ activation, which maintains prostate tissue homeostasis. We have uncovered signaling pathways in BPH-derived prostate epithelial cells (BPH-1) that are impacted by 5AR inhibition. The induction of apoptosis and repression of the cell adhesion protein E-cadherin by the 5AR inhibitor dutasteride requires both ERβ and TGFβ. Dutasteride also induces cyclooxygenase type 2 (COX-2), which functions in a negative feedback loop in TGFβ and ERβ signaling pathways as evidenced by the potentiation of apoptosis induced by dutasteride or finasteride upon pharmacological inhibition or shRNA-mediated ablation of COX-2. Concurrently, COX-2 positively impacts ERβ action through its effect on the expression of a number of steroidogenic enzymes in the ERβ ligand metabolic pathway. Therefore, effective combination pharmacotherapies, which have included non-steroidal anti-inflammatory drugs, must take into account biochemical pathways affected by 5AR inhibition and opposing effects of COX-2 on the tissue-protective action of ERβ.
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http://dx.doi.org/10.1074/jbc.M115.711515DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4938192PMC
July 2016