Browsing by Subject "Oxidative phosphorylation"

Now showing 1 - 5 of 5
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    Assessment of Phase-Dependent Alterations in Cortical Glycolytic and Mitochondrial Metabolism Following Ischemic Stroke
    (Taylor & Francis, 2025) Rahimpour, Shokofeh; Meadows, Ethan; Hollander, John M.; Karelina, Kate; Brown, Candice M.; Anesthesia, School of Medicine
    Maintaining optimal brain metabolism supports neuronal function, synaptic communication, and cognitive processes. During ischemic stroke, brain metabolism and cellular bioenergetics within the neurovascular unit are disrupted, emphasizing the significance of understanding the physiology and pathology of the stroke brain. The objective of this study was to quantify and compare phase-dependent changes in glycolysis and oxidative phosphorylation following ischemic stroke by using the Seahorse XFe24 Analyzer. Since there are limited established methods to quantify glycolytic activity in brain tissue, we optimized the accuracy and reproducibility of extracellular acidification rate (ECAR) measurement by increasing the incubation time following exposure to each reagent. Following optimization, we quantified both ECAR and the oxygen consumption rate (OCR), a measure of oxidative phosphorylation, in cortical brain tissue punches corresponding to the penumbra from mice subjected to ischemic stroke. ECAR and OCR were quantified in tissue punches from the injured (ipsilateral) and the non-injured (contralateral) hemispheres at 48 hours, 7 days, and 14 days post-stroke. Normalized ECAR measurements showed elevated glycolytic activity in the ipsilateral and contralateral hemispheres at 7 days post-stroke compared to other time points. In contrast, normalized OCR measurements showed a modest increase in basal respiration within the ipsilateral hemispheres between 48 hours and 14 days post-stroke. In summary, the results demonstrate that ischemic stroke results in a distinct phase-dependent metabolic phenotype in both cortical hemispheres that persists up to 14 days after injury.
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    Dichloroacetate Reverses the Hypoxic Adaptation to Bevacizumab and Enhances its Antitumor Effects in Mouse Xenografts
    (Springer, 2013) Kumar, Krishnan; Wigfield, Simon; Gee, Harriet E.; Devlin, Cecilia M.; Singleton, Dean; Li, Ji-Liang; Buffa, Francesca; Huffman, Melanie; Sinn, Anthony L.; Silver, Jayne; Turley, Helen; Leek, Russell; Harris, Adrian L.; Ivan, Mircea; Microbiology and Immunology, School of Medicine
    Inhibition of vascular endothelial growth factor increases response rates to chemotherapy and progression-free survival in glioblastoma. However, resistance invariably occurs, prompting the urgent need for identification of synergizing agents. One possible strategy is to understand tumor adaptation to microenvironmental changes induced by antiangiogenic drugs and test agents that exploit this process. We used an in vivo glioblastoma-derived xenograft model of tumor escape in presence of continuous treatment with bevacizumab. U87-MG or U118-MG cells were subcutaneously implanted into either BALB/c SCID or athymic nude mice. Bevacizumab was given by intraperitoneal injection every 3 days (2.5 mg/kg/dose) and/or dichloroacetate (DCA) was administered by oral gavage twice daily (50 mg/kg/dose) when tumor volumes reached 0.3 cm(3) and continued until tumors reached approximately 1.5-2.0 cm(3). Microarray analysis of resistant U87 tumors revealed coordinated changes at the level of metabolic genes, in particular, a widening gap between glycolysis and mitochondrial respiration. There was a highly significant difference between U87-MG-implanted athymic nude mice 1 week after drug treatment. By 2 weeks of treatment, bevacizumab and DCA together dramatically blocked tumor growth compared to either drug alone. Similar results were seen in athymic nude mice implanted with U118-MG cells. We demonstrate for the first time that reversal of the bevacizumab-induced shift in metabolism using DCA is detrimental to neoplastic growth in vivo. As DCA is viewed as a promising agent targeting tumor metabolism, our data establish the timely proof of concept that combining it with antiangiogenic therapy represents a potent antineoplastic strategy.
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    Inhibiting Glycolysis Enhances T Follicular Helper Cell Differentiation and Survival upon Human Immunodeficiency Virus Infection
    (2020-01) Rane, Sushmita Shirish; Yu, Quigui (Andy); Guo, Haitao; Lu, Tao
    Human immunodeficiency virus (HIV) primarily infects T helper (Th) cells. Decrease in the number of Th cells is the hallmark of HIV infection. Latent reservoirs of human immunodeficiency virus (HIV) are the leading barrier towards eradication of HIV infection. T Follicular helper (Tfh) cells are a subset of Th cells that function to provide aid to B cells for their maturation, affinity selection and antibody class switch. Several studies have shown that Tfh cells are a major reservoir of latent as well as productive hiv infection. But in contrast to the fate of other Th cell subsets, the frequency of Tfh cells was shown to have increased during HIV infection which could not be attributed to their reduced susceptibility to HIV infection. The hypothesis was that Tfh cells possess a unique metabolic phenotype that protects them from HIV induced cell death. Transcriptome analysis of Th subsets from human donors and showed that Tfh cells rely less on glycolysis for their energetic requirements and instead have increased transcription of fatty acid synthesis genes. This finding was corroborated by seahorse extracellular flux assay. The results shoId that glycolysis was not essential for Tfh cell differentiation in-vitro. The observed increase in Tfh cell frequency could not be attributed to increased Tfh differentiation upon HIV infection since HIV infection inhibited the differentiation of both non-Tfh and Tfh cells. The results found that bypassing the glycolytic pathway by providing Tfh cells with Galactose in the medium protected ex-vivo infected primary tonsillar cells from HIV induced cell death. This protection could be partly explained by the induction of Baculovirus IAP repeat containing 5 (BIRC5) when the cells utilized Galactose instead of Glucose. The studies together show that Tfh cells have an oxidative metabolic phenotype which protects them from HIV induced cell death in part by induction of BIRC5 expression.
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    Modulation of oxidative phosphorylation and mitochondrial biogenesis by cigarette smoke influence the response to immune therapy in NSCLC patients
    (Elsevier, 2023-04) Wang, Yuezhu; Smith, Margaret; Ruiz, Jimmy; Liu, Yin; Kucera, Gregory L.; Topaloglu, Umit; Chan, Michael D.; Li, Wencheng; Su, Jing; Xing, Fei; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public Health
    The treatment regimen of non-small cell lung cancer (NSCLC) has drastically changed owing to the superior anti-cancer effects generated by the immune-checkpoint blockade (ICB). However, only a subset of patients experience benefit after receiving ICBs. Therefore, it is of paramount importance to increase the response rate by elucidating the underlying molecular mechanisms and identifying novel therapeutic targets to enhance the efficacy of IBCs in non-responders. We analyzed the progression-free survival (PFS) and overall survival (OS) of 295 NSCLC patients who received anti-PD-1 therapy by segregating them with multiple clinical factors including sex, age, race, smoking history, BMI, tumor grade and subtype. We also identified key signaling pathways and mutations that are enriched in patients with distinct responses to ICB by gene set enrichment analysis (GSEA) and mutational analyses. We found that former and current smokers have a higher response rate to anti-PD-1 treatment than non-smokers. GSEA results revealed that oxidative phosphorylation (OXPHOS) and mitochondrial related pathways are significantly enriched in both responders and smokers, suggesting a potential role of cellular metabolism in regulating immune response to ICB. We also demonstrated that all-trans retinoic acid (ATRA) which enhances mitochondrial function significantly enhanced the efficacy of anti-PD-1 treatment in vivo. Our clinical and bioinformatics based analyses revealed a connection between smoking induced metabolic switch and the response to immunotherapy, which can be the basis for developing novel combination therapies that are beneficial to never smoked NSCLC patients.
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    The onset of circulation triggers a metabolic switch required for endothelial to hematopoietic transition
    (Cell Press, 2021) Azzoni, Emanuele; Frontera, Vincent; Anselmi, Giorgio; Rode, Christina; James, Chela; Deltcheva, Elitza M.; Demian, Atanasiu S.; Brown, John; Barone, Cristiana; Patelli, Arianna; Harman, Joe R.; Nicholls, Matthew; Conway, Simon J.; Morrissey, Edward; Jacobsen, Sten Eirik W.; Sparrow, Duncan B.; Harris, Adrian L.; Enver, Tariq; de Bruijn, Marella F.T.R.; Pediatrics, School of Medicine
    Hematopoietic stem cells (HSCs) emerge during development from the vascular wall of the main embryonic arteries. The onset of circulation triggers several processes that provide critical external factors for HSC generation. Nevertheless, it is not fully understood how and when the onset of circulation affects HSC emergence. Here we show that in Ncx1-/- mouse embryos devoid of circulation the HSC lineage develops until the phenotypic pro-HSC stage. However, these cells reside in an abnormal microenvironment, fail to activate the hematopoietic program downstream of Runx1, and are functionally impaired. Single-cell transcriptomics shows that during the endothelial-to-hematopoietic transition, Ncx1-/- cells fail to undergo a glycolysis to oxidative phosphorylation metabolic switch present in wild-type cells. Interestingly, experimental activation of glycolysis results in decreased intraembryonic hematopoiesis. Our results suggest that the onset of circulation triggers metabolic changes that allow HSC generation to proceed.