scholarly journals Thrifty metabolism that favors fat storage after caloric restriction: a role for skeletal muscle phosphatidylinositol‐3‐kinase activity and AMP‐activated protein kinase

2007 ◽  
Vol 22 (3) ◽  
pp. 774-785 ◽  
Author(s):  
S. Summermatter ◽  
D. Mainieri ◽  
A. P. Russell ◽  
J. Seydoux ◽  
J. P. Montani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Caloric Restriction ◽  
Kinase Activity ◽  
Phosphatidylinositol 3 Kinase ◽  
Fat Storage ◽  
Amp Activated Protein Kinase ◽  
Phosphatidylinositol 3

scholarly journals Corticotropin-Releasing Hormone Directly Stimulates Thermogenesis in Skeletal Muscle Possibly through Substrate Cycling between de Novo Lipogenesis and Lipid Oxidation

Endocrinology ◽  
2006 ◽  
Vol 147 (1) ◽  
pp. 31-38 ◽  
Author(s):  
G. Solinas ◽  
S. Summermatter ◽  
D. Mainieri ◽  
M. Gubler ◽  
J. P. Montani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Lipid Oxidation ◽  
De Novo ◽  
De Novo Lipogenesis ◽  
Phosphatidylinositol 3 Kinase ◽  
Intact Mouse ◽  
Amp Activated Protein Kinase ◽  
Protein Kinase Signaling ◽  
Phosphatidylinositol 3

The mechanisms by which CRH and related peptides (i.e. the CRH/urocortin system) exert their control over thermogenesis and weight regulation have until now focused only upon their effects on brain centers controlling sympathetic outflow. Using a method that involves repeated oxygen uptake determinations in intact mouse skeletal muscle, we report here that CRH can act directly on skeletal muscle to stimulate thermogenesis, an effect that is more pronounced in oxidative than in glycolytic muscles and that can be inhibited by a selective CRH-R2 antagonist or blunted by a nonselective CRH receptor antagonist. This thermogenic effect of CRH can also be blocked by interference along pathways of de novo lipogenesis and lipid oxidation, as well as by inhibitors of phosphatidylinositol 3-kinase or AMP-activated protein kinase. Taken together, these studies demonstrate that CRH can directly stimulate thermogenesis in skeletal muscle, and in addition raise the possibility that this thermogenic effect, which requires both phosphatidylinositol 3-kinase and AMP-activated protein kinase signaling, might occur via substrate cycling between de novo lipogenesis and lipid oxidation. The effect of CRH in directly stimulating thermogenesis in skeletal muscle underscores a potentially important peripheral role for the CRH/urocortin system in the control of thermogenesis in this tissue, in its protection against excessive intramyocellular lipid storage, and hence against skeletal muscle lipotoxicity and insulin resistance.

scholarly journals Metformin Increases AMP-Activated Protein Kinase Activity in Skeletal Muscle of Subjects With Type 2 Diabetes

Diabetes ◽  
2002 ◽  
Vol 51 (7) ◽  
pp. 2074-2081 ◽  
Author(s):  
N. Musi ◽  
M. F. Hirshman ◽  
J. Nygren ◽  
M. Svanfeldt ◽  
P. Bavenholm ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Skeletal Muscle ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Protein Kinase Activity ◽  
Amp Activated Protein Kinase

Regulation of phosphatidylinositol 3-kinase by insulin in rat skeletal muscle

1993 ◽  
Vol 265 (5) ◽  
pp. E736-E742 ◽  
Author(s):  
K. S. Chen ◽  
J. C. Friel ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Receptor Protein ◽  
Mammalian Skeletal Muscle ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

The presence of phosphatidylinositol 3-kinase (PI 3-kinase) in mammalian skeletal muscle and its response to insulin stimulation were investigated. PI kinase, immunoprecipitated from rat soleus muscle with antibodies directed toward its 85-kDa subunit phosphorylated PI, phosphatidylinositol 4-phosphate [PI(4)P], and phosphatidylinositol 4,5,-bisphosphate [PI(4,5)P2] to yield phosphatidylinositol 3-phosphate [PI(3)P], phosphatidylinositol 3,4,-bisphosphate, and phosphatidylinositol trisphosphate in vitro. PI 3-kinase activity was also immunoprecipitated with antiphosphotyrosine [alpha-Tyr(P)] antibodies and with antibodies raised against IRS-1, a substrate of the insulin receptor protein tyrosine kinase that associates with and activates PI 3-kinase. Incubation of the soleus with insulin in vitro, or injection of insulin into rats in vivo, produced three- to fivefold increases in alpha-Tyr(P)- and alpha-IRS-1-immunoprecipitable PI 3-kinase activity. In nonstimulated soleus muscle, PI 3-kinase activity immunoprecipitated with alpha-IRS-1 or with alpha-Tyr(P) antibodies was evenly distributed between particulate (200,000-g pellet) and soluble fractions. Insulin treatment increased immunoprecipitable PI 5-kinase activity in both fractions, but the increase in alpha-Tyr-(P)-precipitable activity was greater in the particulate fraction, whereas the increase in alpha-IRS-1-precipitable activity was greater in the soluble fraction. In intact soleus muscles incubated with 32PO4, insulin increased the labeling of PI(3)P but did not affect the labeling of PI(4)P or PI(4,5)P2. Activation of PI 3-kinase by insulin was unaffected by prior denervation of the muscle, a manipulation that has been shown to cause both insulin resistance and hypersensitivity in muscles, depending on the parameter measured.(ABSTRACT TRUNCATED AT 250 WORDS)

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