In Skeletal Muscle, Glucose Storage and Oxidation Are Differentially Impaired by the IR1152 Mutant Receptor

Caruso, Martina; Miele, Claudia; Formisano, Pietro; Condorelli, Gerolama; Bifulco, Giuseppe; Oliva, Anna Maria; Auricchio, Renata; Riccardi, Gabriele; Capaldo, Brunella; Béguinot, Francesco

doi:10.1074/jbc.272.11.7290

Cited by 26 publications

(50 citation statements)

References 40 publications

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“…Detection of glucose transporters at the cell surface was accomplished as previously reported (21). Briefly, L6 cells were preincubated in serum-free DMEM supplemented with 0.25% bovine serum albumin for 24 h and then further incubated in the absence or presence of 100 nmol/l insulin for 30 min.…”

Section: Glucose Transporter Detection and 2-deoxy-d-glucose (2-dg) Umentioning

confidence: 99%

Protein Kinase C (PKC)-α Activation Inhibits PKC-ζ and Mediates the Action of PED/PEA-15 on Glucose Transport in the L6 Skeletal Muscle Cells

et al. 2001

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Overexpression of the PED/PEA-15 protein in muscle and adipose cells increases glucose transport and impairs further insulin induction. Like glucose transport, protein kinase C (PKC)-α and -β are also constitutively activated and are not further stimulatable by insulin in L6 skeletal muscle cells overexpressing PED (L6PED). PKC-ζ features no basal change but completely loses insulin sensitivity in L6PED. In these cells, blockage of PKC-α and -β additively returns 2-deoxy-d-glucose (2-DG) uptake to the levels of cells expressing only endogenous PED (L6WT). Blockage of PKC-α and -β also restores insulin activation of PKC-ζ in L6PED cells, with that of PKC-α sixfold more effective than PKC-β. Similar effects on 2-DG uptake and PKC-ζ were also achieved by 50-fold overexpression of PKC-ζ in L6PED. In L6WT, fivefold overexpression of PKC-α or -β increases basal 2-DG uptake and impairs further insulin induction with no effect on insulin receptor or insulin receptor substrate phosphorylation. In these cells, overexpression of PKC-α blocks insulin induction of PKC-ζ activity. PKC-β is 10-fold less effective than PKC-α in inhibiting PKC-ζ stimulation. Expression of the dominant-negative K281→W PKC-ζ mutant simultaneously inhibits insulin activation of PKC-ζ and 2-DG uptake in the L6WT cells. We conclude that activation of classic PKCs, mainly PKC-α, inhibits PKC-ζ and may mediate the action of PED on glucose uptake in L6 skeletal muscle cells.

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Section: Glucose Transporter Detection and 2-deoxy-d-glucose (2-dg) Umentioning

confidence: 99%

Protein Kinase C (PKC)-α Activation Inhibits PKC-ζ and Mediates the Action of PED/PEA-15 on Glucose Transport in the L6 Skeletal Muscle Cells

et al. 2001

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“…Cellular glucose oxidation rates were determined using modifications of previously published protocols (5,22). C 2 C 12 myoblasts were grown in T25 flasks and differentiated into myotubes as described above.…”

Section: Methodsmentioning

confidence: 99%

PGC-1α Coactivates PDK4 Gene Expression via the Orphan Nuclear Receptor ERRα: a Mechanism for Transcriptional Control of Muscle Glucose Metabolism

Wende¹,

Huss²,

Schaeffer³

et al. 2005

Molecular and Cellular Biology

321

311

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The transcriptional coactivator PGC-1␣ is a key regulator of energy metabolism, yet little is known about its role in control of substrate selection. We found that physiological stimuli known to induce PGC-1␣ expression in skeletal muscle coordinately upregulate the expression of pyruvate dehydrogenase kinase 4 (PDK4), a negative regulator of glucose oxidation. Forced expression of PGC-1␣ in C 2 C 12 myotubes induced PDK4 mRNA and protein expression. PGC-1␣-mediated activation of PDK4 expression was shown to occur at the transcriptional level and was mapped to a putative nuclear receptor binding site. Gel shift assays demonstrated that the PGC-1␣-responsive element bound the estrogen-related receptor ␣ (ERR␣), a recently identified component of the PGC-1␣ signaling pathway. In addition, PGC-1␣ was shown to activate ERR␣ expression. Chromatin immunoprecipitation assays confirmed that PGC-1␣ and ERR␣ occupied the mPDK4 promoter in C 2 C 12 myotubes. Additionally, transfection studies using ERR␣-null primary fibroblasts demonstrated that ERR␣ is required for PGC-1␣-mediated activation of the mPDK4 promoter. As predicted by the effects of PGC-1␣ on PDK4 gene transcription, overexpression of PGC-1␣ in C 2 C 12 myotubes decreased glucose oxidation rates. These results identify the PDK4 gene as a new PGC-1␣/ERR␣ target and suggest a mechanism whereby PGC-1␣ exerts reciprocal inhibitory influences on glucose catabolism while increasing alternate mitochondrial oxidative pathways in skeletal muscle.

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“…Cell Culture and Transfection and Cloning of the KRLB PeptideThe L6 cell clone expressing wild-type human insulin receptors (L6hIR) have been previously characterized and described with the term WT1 (30). The cells were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum, 10,000 units/ml penicillin, 10,000 g/ml streptomycin, and 2% L-glutamine in a humidified CO 2 incubator as described by Caruso et al (30).…”

Section: Methodsmentioning

confidence: 99%

“…The cells were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal calf serum, 10,000 units/ml penicillin, 10,000 g/ml streptomycin, and 2% L-glutamine in a humidified CO 2 incubator as described by Caruso et al (30). Transient transfection of the phosphorothioate oligonucleotides and of the Lys 281 3 Trp dominant negative PKC mutant (31) was performed by the LipofectAMINE method according to the manufacturer's instruction.…”

Section: Methodsmentioning

confidence: 99%

Insulin Receptor Substrate-2 Phosphorylation Is Necessary for Protein Kinase Cζ Activation by Insulin in L6hIR Cells

Oriente

Formisano

Miele

et al. 2001

Journal of Biological Chemistry

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We have investigated glycogen synthase (GS) activation in L6hIR cells expressing a peptide corresponding to the kinase regulatory loop binding domain of insulin receptor substrate-2 (IRS-2) (KRLB). In several clones of these cells (B2, F4), insulin-dependent binding of the KRLB to insulin receptors was accompanied by a block of IRS-2, but not IRS-1, phosphorylation, and insulin receptor binding. GS activation by insulin was also inhibited by >70% in these cells (p < 0.001). The impairment of GS activation was paralleled by a similarly sized inhibition of glycogen synthase kinase 3␣ (GSK3␣) and GSK3␤ inactivation by insulin with no change in protein phosphatase 1 activity. PDK1 (a phosphatidylinositol trisphosphate-dependent kinase) and Akt/protein kinase B (PKB) activation by insulin showed no difference in B2, F4, and in control L6hIR cells. At variance, insulin did not activate PKC in B2 and F4 cells. In L6hIR, inhibition of PKC activity by either a PKC antisense or a dominant negative mutant also reduced by 75% insulin inactivation of GSK3␣ and -␤ (p < 0.001) and insulin stimulation of GS (p < 0.002), similar to Akt/PKB inhibition. In L6hIR, insulin induced protein kinase C (PKC) co-precipitation with GSK3␣ and ␤. PKC also phosphorylated GSK3␣ and -␤. Alone, these events did not significantly affect GSK3␣ and -␤ activities. Inhibition of PKC activity, however, reduced Akt/PKB phosphorylation of the key serine sites on GSK3␣ and -␤ by >80% (p < 0.001) and prevented full GSK3 inactivation by insulin. Thus, IRS-2, not IRS-1, signals insulin activation of GS in the L6hIR skeletal muscle cells. In these cells, insulin inhibition of GSK3␣ and -␤ requires dual phosphorylation by both Akt/PKB and PKC.

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In Skeletal Muscle, Glucose Storage and Oxidation Are Differentially Impaired by the IR1152 Mutant Receptor

Cited by 26 publications

References 40 publications

Protein Kinase C (PKC)-α Activation Inhibits PKC-ζ and Mediates the Action of PED/PEA-15 on Glucose Transport in the L6 Skeletal Muscle Cells

Protein Kinase C (PKC)-α Activation Inhibits PKC-ζ and Mediates the Action of PED/PEA-15 on Glucose Transport in the L6 Skeletal Muscle Cells

PGC-1α Coactivates PDK4 Gene Expression via the Orphan Nuclear Receptor ERRα: a Mechanism for Transcriptional Control of Muscle Glucose Metabolism

Insulin Receptor Substrate-2 Phosphorylation Is Necessary for Protein Kinase Cζ Activation by Insulin in L6hIR Cells

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