scholarly journals A Cistanches Herba Fraction/β-Sitosterol Causes a Redox-Sensitive Induction of Mitochondrial Uncoupling and Activation of Adenosine Monophosphate-Dependent Protein Kinase/Peroxisome Proliferator-Activated ReceptorγCoactivator-1 in C2C12 Myotubes: A Possible Mechanism Underlying the Weight Reduction Effect

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Hoi Shan Wong ◽  
Jihang Chen ◽  
Pou Kuan Leong ◽  
Hoi Yan Leung ◽  
Wing Man Chan ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Weight Reduction ◽  
Uncoupling Protein ◽  
Adenosine Monophosphate ◽  
C2c12 Myotubes ◽  
Metabolic Enzyme ◽  
Peroxisome Proliferator ◽  
Mitochondrial Uncoupling ◽  
Dependent Protein Kinase ◽  
Dependent Protein

Previous studies have demonstrated that HCF1, a semipurified fraction of Cistanches Herba, causes weight reduction in normal diet- and high fat diet-fed mice. The weight reduction was associated with the induction of mitochondrial uncoupling and changes in metabolic enzyme activities in mouse skeletal muscle. To further investigate the biochemical mechanism underlying the HCF1-induced weight reduction, the effect of HCF1 and its active component,β-sitosterol (BSS), on C2C12 myotubes was examined. Incubation with HCF1/BSS caused a transient increase in mitochondrial membrane potential (MMP), possibly by fluidizing the mitochondrial inner membrane. The increase in MMP was paralleled to an increase in mitochondrial reactive oxygen species (ROS) production. Mitochondrial ROS, in turn, triggered a redox-sensitive induction of mitochondrial uncoupling by uncoupling protein 3 (UCP3). Biochemical analysis indicated that HCF1 was capable of activating an adenosine monophosphate-dependent protein kinase/peroxisome proliferator-activated receptorγcoactivator-1 pathway and thereby increased the expression of cytochrome c oxidase and UCP3. Animal studies using mitochondrial recoupler also confirmed the role of mitochondrial uncoupling in the HCF1-induced weight reduction. In conclusion, a HCF1/BSS causes the redox-sensitive induction of mitochondrial uncoupling and activation of AMPK/PGC-1 in C2C12 myotubes, with resultant reductions in body weight and adiposity by increased energy consumption.

scholarly journals Deletion of CaMKK2 from the Liver Lowers Blood Glucose and Improves Whole-Body Glucose Tolerance in the Mouse

2012 ◽  
Vol 26 (2) ◽  
pp. 281-291 ◽  
Author(s):  
Kristin A. Anderson ◽  
Fumin Lin ◽  
Thomas J. Ribar ◽  
Robert D. Stevens ◽  
Michael J. Muehlbauer ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Protein Kinase ◽  
Glucose Tolerance ◽  
Glucose Intolerance ◽  
De Novo Lipogenesis ◽  
Whole Body ◽  
Peroxisome Proliferator ◽  
Dependent Protein Kinase ◽  
Peroxisome Proliferator Activated Receptor ◽  
Dependent Protein

Abstract Ca2+/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a member of the Ca2+/CaM-dependent protein kinase family that is expressed abundantly in brain. Previous work has revealed that CaMKK2 knockout (CaMKK2 KO) mice eat less due to a central nervous system -signaling defect and are protected from diet-induced obesity, glucose intolerance, and insulin resistance. However, here we show that pair feeding of wild-type mice to match food consumption of CAMKK2 mice slows weight gain but fails to protect from diet-induced glucose intolerance, suggesting that other alterations in CaMKK2 KO mice are responsible for their improved glucose metabolism. CaMKK2 is shown to be expressed in liver and acute, specific reduction of the kinase in the liver of high-fat diet-fed CaMKK2floxed mice results in lowered blood glucose and improved glucose tolerance. Primary hepatocytes isolated from CaMKK2 KO mice produce less glucose and have decreased mRNA encoding peroxisome proliferator-activated receptor γ coactivator 1-α and the gluconeogenic enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, and these mRNA fail to respond specifically to the stimulatory effect of catecholamine in a cell-autonomous manner. The mechanism responsible for suppressed gene induction in CaMKK2 KO hepatocytes may involve diminished phosphorylation of histone deacetylase 5, an event necessary in some contexts for derepression of the peroxisome proliferator-activated receptor γ coactivator 1-α promoter. Hepatocytes from CaMKK2 KO mice also show increased rates of de novo lipogenesis and fat oxidation. The changes in fat metabolism observed correlate with steatotic liver and altered acyl carnitine metabolomic profiles in CaMKK2 KO mice. Collectively, these results are consistent with suppressed catecholamine-induced induction of gluconeogenic gene expression in CaMKK2 KO mice that leads to improved whole-body glucose homeostasis despite the presence of increased hepatic fat content.

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