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Full-Text Articles in Translational Medical Research
Effects Of Tumor Necrosis Factor-Α On Glucose Metabolism In Cultured Human Muscle Cells From Nondiabetic And Type 2 Diabetic Subjects, Theodore P. Ciaraldi, Leslie Carter, Sunder Mudaliar, Philip A. Kern, Robert R. Henry
Effects Of Tumor Necrosis Factor-Α On Glucose Metabolism In Cultured Human Muscle Cells From Nondiabetic And Type 2 Diabetic Subjects, Theodore P. Ciaraldi, Leslie Carter, Sunder Mudaliar, Philip A. Kern, Robert R. Henry
Clinical and Translational Science Faculty Publications
The effects of tumor necrosis factor-a (TNFα) on glucose uptake and glycogen synthase (GS) activity were studied in human skeletal muscle cell cultures from nondiabetic and type 2 diabetic subjects. In nondiabetic muscle cells, acute (90-Min) exposure to TNFα (5 ng/ml) stimulated glucose uptake (73 ± 14% increase) to a greater extent than insulin (37 ± 4%; P < 0.02). The acute uptake response to TNFα in diabetic cells (51 ± 6% increase) was also greater than that to insulin (31 ± 3%; P < 0.05). Prolonged (24-h) exposure of nondiabetic muscle cells to TNFα resulted in a further stimulation of uptake (152 ± 31%; P < 0.05), whereas the increase in cells from type 2 diabetics was not significant compared with that in cells receiving acute treatment. After TNFα treatment, the level of glucose transporter-1 protein was elevated in nondiabetic (4.6-fold increase) and type 2 (1.7-fold) cells. Acute TNFα treatment had no effect on the fractional velocity of GS in either nondiabetic or type 2 cells. Prolonged exposure reduced the GS fractional velocity in both nondiabetic and diabetic cells. In summary, both acute and prolonged treatment with TNFα up-regulate glucose uptake activity in cultured human muscle cells, but reduce GS activity. Increased skeletal muscle glucose uptake in conditions of TNFα excess may serve as a compensatory mechanism in the insulin resistance of type 2 diabetes.
Potential Role Of Tnfα And Lipoprotein Lipase As Candidate Genes For Obesity, Philip A. Kern
Potential Role Of Tnfα And Lipoprotein Lipase As Candidate Genes For Obesity, Philip A. Kern
Clinical and Translational Science Faculty Publications
To maintain body weight, metabolic efficiency was promoted during evolution; two candidate genes for body weight regulation are lipoprotein lipase (LPL) and tumor necrosis factor-α [TNFα). Human fat cells do not synthesize lipid, but rely on LPL-mediated plasma triglyceride hydrolysis. Adipose LPL is elevated in obesity. Following weight loss, LPL is elevated further, suggesting attempts to maintain lipid stores during fasting and to replenish lipid stores during refeeding. Muscle LPL is regulated inversely to adipose LPL. Thus, an increased adipose/muscle LPL ratio would partition dietary lipid into adipose tissue and would explain some of the variability in weight gain when …