Improved insulin‐stimulated glucose uptake and glycogen synthase activation in rat skeletal muscles after adrenaline infusion: role of glycogen content and PKB phosphorylation

Jensen, Jørgen; Ruzzin, Jérôme; Jebens, Einar; Brennesvik, Erlend O.; Knardahl, Stein

doi:10.1111/j.1365-201x.2005.01437.x

Cited by 35 publications

(37 citation statements)

References 43 publications

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“…Stimulation of cell proliferative effects by cAMP in a PKA-independent manner often requires activation of Rap1 via Epac [15,16]. Here the cell proliferative effects of cAMP are mediated by the activation of the PI 3-kinase/Akt signaling pathway as demonstrated by the lack of an effect by PKA inhibitors, in contrast to an inhibitory effect observed with PI 3-kinase inhibitors [19][20][21][22]. An increase in intracellular cAMP activates Akt1 by phosphorylating it on both Thr 308 and Ser 473 [25,24].…”

Section: Introductionmentioning

confidence: 65%

“…Binding of intracellular cAMP to Epac1 in stimulated cells triggers activation of Epac1-Rap1 signaling, one component of which is the activation of the protein kinase Akt which is sensitive to inhibition of PI 3-kinase [17][18][19][20][21][22]. Likewise, TCL1 facilitates activation of the protein kinase Akt consequent to its binding to the PH domain of Akt [1,3,4].…”

Section: Activation Of Akt Protein Kinases In Tcl1 Immunoprecipitatesmentioning

confidence: 99%

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Interaction between TCL1 and Epac1 in the activation of Akt kinases in plasma membranes and nuclei of 8-CPT-2-O-Me-cAMP-stimulated macrophages

Misra

Kaczowka

Pizzo

2008

Cellular Signalling

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Epac1 is a cAMP-stimulated guanine exchange factor that activates Rap1. The protein product of the T cell leukemia 1 (TCL1) proto-oncogene binds to Akt enhancing its kinase activity. TCL1 and Epac promote cellular proliferation because of their activating effects on Akt. Employing macrophages, we have studied the mechanisms whereby these proteins function in the regulation of Akt kinase activity. Cells were treated with 8-CPT-2-O-Me-cAMP, a cAMP analog which acts selectively and specifically via Epac1. Epac1 co-immunoprecipitated with TCL1 in plasma membrane and nuclear fractions of 8-CPT-2-O-Me-cAMP-stimulated macrophages. Interaction of TCL1 and Epac1 was also observed in a [ 125 I]GST-Epac1 pulldown assay. A two-threefold increase in Akt and Akt Ser-473 protein kinase activities and their phosphoprotein levels was observed in TCL1 immunoprecipitates of plasma membranes and nuclei of the treated cells. Elevated Akt Thr-308 protein kinase activity and its phosphoprotein levels were significantly reduced in TCL1 immunoprecipitates of plasma membranes of 8-CPT-2-O-Me-cAMP treated cells where Epac1 gene expression was silenced. In contrast, Akt Ser-473 protein kinase activity and its phosphoprotein levels were reduced only in plasma membranes. Our studies suggest that a ternary complex of TCL1, Epac1, and Akt forms in activated macrophages both promoting Akt activation and regulating intracellular distribution of Akt. KeywordsCyclic AMP generation in macrophages; 8-CPT-2-O-Me-cAMP and cyclic AMP-dependent regulation in macrophages; Akt protein kinase activation; Epac-1 and TCL1 interaction; protein kinases Akt in nuclei and plasma membranes

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Section: Introductionmentioning

confidence: 65%

Section: Activation Of Akt Protein Kinases In Tcl1 Immunoprecipitatesmentioning

confidence: 99%

Interaction between TCL1 and Epac1 in the activation of Akt kinases in plasma membranes and nuclei of 8-CPT-2-O-Me-cAMP-stimulated macrophages

Misra

Kaczowka

Pizzo

2008

Cellular Signalling

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“…Glycogen content was determined as glucose units analyzed fluorometrically with appropriate standard curve (27). In muscles where rates of glycogen synthesis were measured, 100 l of the KOH digest was neutralized and hydrolyzed with amyloglucosidase, and glucose units were analyzed as described previously (15).…”

Section: Chemicalsmentioning

confidence: 99%

Glycogen content and contraction regulate glycogen synthase phosphorylation and affinity for UDP-glucose in rat skeletal muscles

Lai¹,

Stuenæs²,

Kuo³

et al. 2007

American Journal of Physiology-Endocrinology and Metabolism

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“…This result could be related to the improvements in both muscular and neuronal components secondary to the improvement in insulin sensitivity. Increasing peripheral insulin action could result in better capability to store glycogen [23] and a reduced rate of muscle protein degradation [24]. This effect is beneficial in preserving greater anaerobic fuel and normal contractile property of skeletal muscle in response to acute physical challenge.…”

Section: Discussionmentioning

confidence: 99%

A Possible Link Between Exercise-training Adaptation And Dehydroepiandrosterone Sulfate- An Oldest-old Female Study

Chen

Lee

Huang

et al. 2007

Medicine &Amp; Science in Sports &Amp; Exercise

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The purpose of this study was to determine the association between the level of salivary dehydroepiandrosterone sulfate (DHEA-S) and the magnitude of adaptation to exercise training in insulin sensitivity for aged females. A group of 16 females, aged 80-93 years old, was divided into 2 groups according to their baseline DHEA-S levels: Lower Halves (N = 8) and Upper Halves (N = 8), and participated in a 4-month exercise intervention trial. Insulin response with an oral glucose tolerance test (OGTT), cholesterol, blood pressure (BP), motor performance, and DHEA-S were determined at baseline and 4 months after the training program. Glucose tolerance and body mass index (BMI) remained unchanged with training for both groups. Insulin, fasted cholesterol, diastolic blood pressure, reaction time, and locomotive function were significantly lowered by training only in the Upper Halves group. Changes in the area under curve of insulin (IAUC) were negatively correlated with the baseline DHEA-S level (R= -0.60, P < 0.05). The current study provides the first evidence that oldest-old subjects with low DHEA-S level appear to be poor responders to exercise-training adaptations.

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Improved insulin‐stimulated glucose uptake and glycogen synthase activation in rat skeletal muscles after adrenaline infusion: role of glycogen content and PKB phosphorylation

Cited by 35 publications

References 43 publications

Interaction between TCL1 and Epac1 in the activation of Akt kinases in plasma membranes and nuclei of 8-CPT-2-O-Me-cAMP-stimulated macrophages

Interaction between TCL1 and Epac1 in the activation of Akt kinases in plasma membranes and nuclei of 8-CPT-2-O-Me-cAMP-stimulated macrophages

Glycogen content and contraction regulate glycogen synthase phosphorylation and affinity for UDP-glucose in rat skeletal muscles

A Possible Link Between Exercise-training Adaptation And Dehydroepiandrosterone Sulfate- An Oldest-old Female Study

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