Browsing by Subject "Glucose transport"

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    Metabolic transcriptomics dictate responses of cone photoreceptors to retinitis pigmentosa
    (Cell Press, 2023) Lee, Sang Joon; Emery, Douglas; Vukmanic, Eric; Wang, Yekai; Lu, Xiaoqin; Wang, Wei; Fortuny, Enzo; James, Robert; Kaplan, Henry J.; Liu, Yongqing; Du, Jianhai; Dean, Douglas C.; Neurological Surgery, School of Medicine
    Most mutations in retinitis pigmentosa (RP) arise in rod photoreceptors, but cone photoreceptors, responsible for high-resolution daylight and color vision, are subsequently affected, causing the most debilitating features of the disease. We used mass spectroscopy to follow 13C metabolites delivered to the outer retina and single-cell RNA sequencing to assess photoreceptor transcriptomes. The S cone metabolic transcriptome suggests engagement of the TCA cycle and ongoing response to ROS characteristic of oxidative phosphorylation, which we link to their histone modification transcriptome. Tumor necrosis factor (TNF) and its downstream effector RIP3, which drive ROS generation via mitochondrial dysfunction, are induced and activated as S cones undergo early apoptosis in RP. The long/medium-wavelength (L/M) cone transcriptome shows enhanced glycolytic capacity, which maintains their function as RP progresses. Then, as extracellular glucose eventually diminishes, L/M cones are sustained in long-term dormancy by lactate metabolism.
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    Muscle-Specific Ablation of Glucose Transporter 1 (GLUT1) Does Not Impair Basal or Overload-Stimulated Skeletal Muscle Glucose Uptake
    (MDPI, 2022-11-23) McMillin, Shawna L.; Evans, Parker L.; Taylor, William M.; Weyrauch, Luke A.; Sermersheim, Tyler J.; Welc, Steven S.; Heitmeier, Monique R.; Hresko, Richard C.; Hruz, Paul W.; Koumanov, Francois; Holman, Geoffrey D.; Abel, E. Dale; Witczak, Carol A.; Anatomy, Cell Biology and Physiology, School of Medicine
    Glucose transporter 1 (GLUT1) is believed to solely mediate basal (insulin-independent) glucose uptake in skeletal muscle; yet recent work has demonstrated that mechanical overload, a model of resistance exercise training, increases muscle GLUT1 levels. The primary objective of this study was to determine if GLUT1 is necessary for basal or overload-stimulated muscle glucose uptake. Muscle-specific GLUT1 knockout (mGLUT1KO) mice were generated and examined for changes in body weight, body composition, metabolism, systemic glucose regulation, muscle glucose transporters, and muscle [3H]-2-deoxyglucose uptake ± the GLUT1 inhibitor BAY-876. [3H]-hexose uptake ± BAY-876 was also examined in HEK293 cells-expressing GLUT1-6 or GLUT10. mGLUT1KO mice exhibited no impairments in body weight, lean mass, whole body metabolism, glucose tolerance, basal or overload-stimulated muscle glucose uptake. There was no compensation by the insulin-responsive GLUT4. In mGLUT1KO mouse muscles, overload stimulated higher expression of mechanosensitive GLUT6, but not GLUT3 or GLUT10. In control and mGLUT1KO mouse muscles, 0.05 µM BAY-876 impaired overload-stimulated, but not basal glucose uptake. In the GLUT-HEK293 cells, BAY-876 inhibited glucose uptake via GLUT1, GLUT3, GLUT4, GLUT6, and GLUT10. Collectively, these findings demonstrate that GLUT1 does not mediate basal muscle glucose uptake and suggest that a novel glucose transport mechanism mediates overload-stimulated glucose uptake.