Phosphatidylinositol 3-kinase and dynamics of insulin resistance in denervated slow and fast muscles in vivo

1997 ◽  
Vol 272 (4) ◽  
pp. E661-E670 ◽  
Author(s):  
J. S. Elmendorf ◽  
A. Damrau-Abney ◽  
T. R. Smith ◽  
T. S. David ◽  
J. Turinsky
Keyword(s):  
Insulin Receptor ◽  
Glucose Uptake ◽  
Soleus Muscle ◽  
Phosphatidylinositol 3 Kinase ◽  
Plantaris Muscle ◽  
Glut 1 ◽  
Glut 4 ◽  
Denervated Muscles ◽  
Phosphatidylinositol 3

Regulation of glucose uptake by 1- and 3-day denervated soleus (slow-twitch) and plantaris (fast-twitch) muscles in vivo was investigated. One day after denervation, soleus and plantaris muscles exhibited 62 and 65% decreases in insulin-stimulated 2-deoxyglucose uptake, respectively, compared with corresponding control muscles. At this interval, denervated muscles showed no alterations in insulin receptor binding and activity, amount and activity of phosphatidylinositol 3-kinase, and amounts of GLUT-1 and GLUT-4. Three days after denervation, there was no increase in 2-deoxyglucose uptake in response to insulin in soleus muscle, whereas plantaris muscle exhibited a 158% increase in basal and an almost normal absolute increment in insulin-stimulated uptake. Despite these differences, denervated soleus and plantaris muscles exhibited comparable decreases in insulin-stimulated activities of the insulin receptor (approximately 40%) and phosphatidylinositol 3-kinase (approximately 50%) and a pronounced decrease in GLUT-4. An increase in GLUT-1 in plantaris, but not soleus, muscle 3 days after denervation is consistent with augmented basal 2-deoxyglucose uptake in plantaris muscle at this interval. These results demonstrate that, in denervated muscles, there is a clear dissociation between insulin-stimulated 2-deoxyglucose uptake and upstream events involved in insulin-stimulated glucose uptake.

scholarly journals Sphingomyelinase has an insulin-like effect on glucose transporter translocation in adipocytes

1998 ◽  
Vol 274 (5) ◽  
pp. R1446-R1453 ◽  
Author(s):  
T. S. David ◽  
P. A. Ortiz ◽  
T. R. Smith ◽  
J. Turinsky
Keyword(s):  
Plasma Membrane ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Signaling Pathway ◽  
Insulin Signaling ◽  
Glucose Transporter ◽  
Insulin Signaling Pathway ◽  
Glut 1 ◽  
Glut 4 ◽  
Glut 4 Translocation

Rat epididymal adipocytes were incubated with 0, 0.1, and 1 mU sphingomyelinase/ml for 30 or 60 min, and glucose uptake and GLUT-1 and GLUT-4 translocation were assessed. Adipocytes exposed to 1 mU sphingomyelinase/ml exhibited a 173% increase in glucose uptake. Sphingomyelinase had no effect on the abundance of GLUT-1 in the plasma membrane of adipocytes. In contrast, 1 mU sphingomyelinase/ml increased plasma membrane content of GLUT-4 by 120% and produced a simultaneous decrease in GLUT-4 abundance in the low-density microsomal fraction. Sphingomyelinase had no effect on tyrosine phosphorylation of either the insulin receptor β-subunit or the insulin receptor substrate-1, a signaling molecule in the insulin signaling pathway. It is concluded that the incubation of adipocytes with sphingomyelinase results in insulin-like translocation of GLUT-4 to the plasma membrane and that this translocation does not occur via the activation of the initial components of the insulin signaling pathway.

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)

Glucose uptake and glucose transporter proteins in skeletal muscle from undernourished rats

2001 ◽  
Vol 281 (5) ◽  
pp. E1101-E1109 ◽  
Author(s):  
María Agote ◽  
Luis Goya ◽  
Sonia Ramos ◽  
Carmen Alvarez ◽  
M. Lucía Gavete ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Glucose Transporter ◽  
Subcellular Fractionation ◽  
Phosphatidylinositol 3 Kinase ◽  
Glut 4 ◽  
Gastrocnemius Muscles ◽  
Glucose Transporter Proteins ◽  
And Control

Undernutrition in rats impairs secretion of insulin but maintains glucose normotolerance, because muscle tissue presents an increased insulin-induced glucose uptake. We studied glucose transporters in gastrocnemius muscles from food-restricted and control anesthetized rats under basal and euglycemic hyperinsulinemic conditions. Muscle membranes were prepared by subcellular fractionation in sucrose gradients. Insulin-induced glucose uptake, estimated by a 2-deoxyglucose technique, was increased 4- and 12-fold in control and food-restricted rats, respectively. Muscle insulin receptor was increased, but phosphotyrosine-associated phosphatidylinositol 3-kinase activity stimulated by insulin was lower in undernourished rats, whereas insulin receptor substrate-1 content remained unaltered. The main glucose transporter in the muscle, GLUT-4, was severely reduced albeit more efficiently translocated in response to insulin in food-deprived rats. GLUT-1, GLUT-3, and GLUT-5, minor isoforms in skeletal muscle, were found increased in food-deprived rats. The rise in these minor glucose carriers, as well as the improvement in GLUT-4 recruitment, is probably insufficient to account for the insulin-induced increase in the uptake of glucose in undernourished rats, thereby suggesting possible changes in other steps required for glucose metabolism.

scholarly journals Specific activity of phosphatidylinositol 3-kinase is increased by insulin stimulation

1993 ◽  
Vol 290 (2) ◽  
pp. 327-333 ◽  
Author(s):  
M Okamoto ◽  
T Hayashi ◽  
S Kono ◽  
G Inoue ◽  
M Kubota ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Protein Concentration ◽  
Specific Activity ◽  
Phosphatidylinositol 3 Kinase ◽  
Insulin Stimulation ◽  
Pi3k Activity ◽  
Before And After ◽  
Receptor Beta ◽  
Phosphatidylinositol 3

We investigated whether phosphatidylinositol 3-kinase (PI3K) is phosphorylated and whether its specific activity is increased by insulin stimulation in vivo using Fao cells and antibodies raised against the 85 kDa subunit of PI3K, insulin-receptor substrate-1 (IRS-1), and phosphotyrosine (pTyr). PI3K activity was detected in the immunoprecipitate produced with anti-PI3K at a basal state. The activity was increased 2-3-fold by insulin stimulation, although the protein concentration of kinase in the anti-PI3K immunoprecipitates was the same before and after insulin stimulation. Both anti-pTyr and anti-IRS-1 antibodies immunoprecipitated the kinase activity only after insulin stimulation. After the first immunoprecipitation with anti-pTyr, the supernatant was immunoprecipitated once more with anti-PI3K. PI3K activity in the second immunoprecipitate revealed little difference between the basal and insulin-stimulated states, suggesting that most of the insulin-activated portion of PI3K was precipitated by anti-pTyr. Both IRS-1 and the insulin-receptor beta-subunit (95 kDa) were phosphorylated on tyrosine residues by insulin stimulation and immunoprecipitated with anti-pTyr. However, phosphorylation of neither subunit of PI3K (85 kDa or 110 kDa) was detectable in the immunoprecipitate produced with anti-pTyr. The 185 kDa pTyr-containing protein was immunoprecipitated with anti-PI3K after insulin stimulation, although there was little phosphorylation of the 85 kDa protein. pTyr in the 110 kDa protein immunoprecipitated with anti-PI3K was below detectable levels. These results indicate that the specific activity of PI3K is increased by insulin stimulation without detectable tyrosine phosphorylation of PI3K itself in Fao cells. The majority of the insulin-activated portion of PI3K is associated with pTyr-containing proteins including IRS-1, which suggests that this is important for activation of PI3K by insulin.

Changes in tyrosine phosphorylation of insulin receptor and insulin receptor substrate-1 (IRS-1) and association of p85 subunit of phosphatidylinositol 3-kinase with IRS-1 after feeding in rat liver in vivo

1997 ◽  
Vol 154 (2) ◽  
pp. 267-273 ◽  
Author(s):  
Y Ito ◽  
M Ariga ◽  
S-I Takahashi ◽  
A Takenaka ◽  
T Hidaka ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Tyrosine Phosphorylation ◽  
Rat Liver ◽  
Insulin Receptor Substrate ◽  
Β Subunit ◽  
Phosphatidylinositol 3 Kinase ◽  
Insulin Receptor Substrate 1 ◽  
Insulin Receptor Tyrosine Kinase ◽  
Phosphatidylinositol 3

Abstract The binding of insulin to its receptor rapidly induces intrinsic insulin receptor tyrosine kinase activity, resulting in tyrosine phosphorylation of various cytosolic substrates, such as insulin receptor substrate-1 (IRS-1) which, in turn, associates with a p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase) followed by activation of this enzyme. In the present study, we have examined these early steps of insulin signalling in rat liver in vivo after food ingestion. After fasting for 22 h, a 12% casein diet was available ad libitum throughout the 8-h experimental period. Plasma insulin concentrations increased within 45 min after feeding, reached a maximum at 1·5 h and gradually decreased until 8 h. Autophosphorylation of the insulin receptor β-subunit in liver was detected even during fasting and increased about 1·5-fold at 1·5 h after feeding. Basal tyrosine phosphorylation of IRS-1 was detectable during starvation, increased about twofold at 3 h after feeding and levels were maintained until 8 h. The content of the p85 subunit of PI 3-kinase associated with IRS-1 also increased after feeding in parallel with the changes in tyrosine phosphorylation of IRS-1. Because tyrosine phosphorylation of the insulin receptor β-subunit and IRS-1 and the association of the p85 subunit of PI 3-kinase with IRS-1 in liver were closely correlated with the changes in the plasma concentration of insulin, we concluded that endogenous insulin secreted in response to eating caused these insulin-dependent intracellular changes in the liver. Journal of Endocrinology (1997) 154, 267–273

Akt kinases and 2-deoxyglucose uptake in rat skeletal muscles in vivo: study with insulin and exercise

1999 ◽  
Vol 276 (1) ◽  
pp. R277-R282 ◽  
Author(s):  
Jiri Turinsky ◽  
Alice Damrau-Abney
Keyword(s):  
Glucose Uptake ◽  
Soleus Muscle ◽  
Insulin Injection ◽  
Plantaris Muscle ◽  
Hindlimb Muscles ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Exercise Induced ◽  
Calf Muscles

Activities of Akt1, Akt2, and Akt3 kinases and glucose uptake in hindlimb muscles of the rat in vivo were investigated. The rats were studied either after intravenous injection of 0.1 U of insulin or during exercise induced by stimulating calf muscles electrically at 1 contraction/s. Akt kinases were immunoprecipitated from supernatants of muscle homogenates. Glucose uptake by muscles in vivo was assessed by cellular accumulation of 2-deoxy-d-[1,2-3H(N)]glucose. Administration of insulin resulted in rapid activation of Akt1 kinase, with peak activity observed 5 min after insulin injection. Soleus muscle, a slow-twitch muscle, and plantaris muscle, a fast-twitch muscle, differed in their content of Akt1 kinase and in their response to insulin. Soleus muscle exhibited a 105% higher abundance of Akt1 kinase, a 101% higher insulin-stimulated activity of Akt1 kinase, and 83% higher insulin-stimulated 2-deoxyglucose uptake compared with plantaris muscle. Additionally, insulin administration increased the activities of Akt1, Akt2, and Akt3 kinases in calf muscles and caused a sevenfold augmentation in 2-deoxyglucose uptake by these muscles. In contrast, the exercised calf muscles exhibited an increase in Akt1 kinase activity at 5, 15, and 25 min of exercise but no change in activities of Akt2 and Akt3 isoforms, and the 2-deoxyglucose uptake by calf muscles exercised for 25 min was 11-fold higher compared with muscles of resting rats. The data demonstrate that 1) there is a close, direct correlation between the magnitude of insulin-stimulated activity of Akt1 kinase and the level of glucose uptake in muscles with different fiber populations, 2) insulin activates three isoforms of Akt kinase in skeletal muscle, and 3) exercise in vivo is associated with activation of Akt1 but not Akt2 and Akt3 kinases in contracting muscles.

scholarly journals Peripheral Dopamine Directly Acts on Insulin-Sensitive Tissues to Regulate Insulin Signaling and Metabolic Function

2021 ◽  
Vol 12 ◽  
Author(s):  
Gabriela Tavares ◽  
Fatima. O. Martins ◽  
Bernardete. F. Melo ◽  
Paulo Matafome ◽  
Silvia. V. Conde
Keyword(s):  
Adipose Tissue ◽  
Insulin Receptor ◽  
Glucose Uptake ◽  
Dopamine Receptor ◽  
Soleus Muscle ◽  
Metabolic Function ◽  
Direct Effects ◽  
Brown Adipose ◽  
Dopamine Receptor 1

Dopamine is a key regulator of glucose metabolism in the central nervous system. However, dopamine is also present in the periphery and may have direct effects on insulin-sensitive tissues. Dopamine receptor 2 (D2R) agonist bromocriptine is a FDA-approved drug for type 2 diabetes. Herein, we explored the role of peripheral dopamine and its receptors in regulating glucose uptake and metabolism on insulin-sensitive tissues. Peripheral dopamine effect in [3H]2-deoxyglucose uptake in insulin-sensitive tissues was tested in vivo in rats. Direct effects on [3H]2-deoxyglucose uptake, insulin receptor phosphorylation, and regulation of metabolic function were tested ex vivo in the liver, soleus muscle, and white and brown adipose tissues. Bromocriptine and the antagonists domperidone, D2R antagonist, and haloperidol, antagonist of both dopamine receptor 1 (D1R) and D2R, were used to disclose dopamine receptors’ involvement.Peripheral dopamine increases glucose uptake in vivo. Ex vivo, only dopamine increased glucose uptake in the soleus, while bromocriptine increased it in the liver; the effects were reverted by haloperidol and domperidone, respectively. In adipose tissue, domperidone reverted dopamine- and bromocriptine-mediated potentiation of insulin-induced glucose uptake, but in turn increased the insulin receptor, Akt, AMPK, HSL, ACC, and ACL, phosphorylation. In the soleus muscle, AMPK-phosphorylation increased with bromocriptine and dopamine whose effects were suppressed by domperidone and haloperidol.In conclusion, peripheral dopamine stimulates glucose uptake with its receptors being differentially involved in glucose uptake in insulin-sensitive tissues. Dopamine also has a role in lipid metabolism in white adipose tissue. Altogether, these results suggest that peripheral modulation of the dopaminergic system should be further evaluated as a putative therapeutic approach for metabolic disorders.

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