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Simvastatin may induce insulin resistance through a novel fatty acid mediated cholesterol independent mechanism.

Kain V, Kapadia B, Misra P, Saxena U - Sci Rep (2015)

Bottom Line: Statins are a class of oral drugs that are widely used for treatment of hypercholesterolemia.We explored the possible mechanism of statin induced insulin resistance using a well-established cell based model and simvastatin as a prototype statin.Our data show that simvastatin induces insulin resistance in a cholesterol biosynthesis inhibition independent fashion but does so by a fatty acid mediated effect on insulin signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India.

ABSTRACT
Statins are a class of oral drugs that are widely used for treatment of hypercholesterolemia. Recent clinical data suggest that chronic use of these drugs increases the frequency of new onset diabetes. Studies to define the risks of statin-induced diabetes and its underlying mechanisms are clearly necessary. We explored the possible mechanism of statin induced insulin resistance using a well-established cell based model and simvastatin as a prototype statin. Our data show that simvastatin induces insulin resistance in a cholesterol biosynthesis inhibition independent fashion but does so by a fatty acid mediated effect on insulin signaling pathway. These data may help design strategies for prevention of statin induced insulin resistance and diabetes in patients with hypercholesterolemia.

No MeSH data available.


Related in: MedlinePlus

(a) Simvastatin treatment inhibits insulin signaling cascade: L6 myotubes were cultured in Simvastatin for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612, Tyr608) and pAKT. Total IRS-1, AKT and Beta-actin served as loading control. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4. (b) Densitometric quantification results for western blots from Fig. 4A are shown. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal (DMSO) of control cells which was set to 1; a,dp < 0.05 versus DMSO + insulin treated cells, b,cp < 0.005 versus corresponding DMSO treated cells (two way ANOVA). (c) Inhibition of PKC rescues Simvastatin inhibited insulin mediated glucose uptake: Mean basal and insulin stimulated (5 min and 10 min) uptake of 2-NBDG by L6 myotubes treated with Simvastatin (1 μM) and/or PKC inhibitors (Bisindolylmaleimide I, Bis (1 μM) and GÖ6983 (1 μM) for different time points as indicated. DMSO (0.1%) treated cells served as internal control. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal of control cells which was set to 1; **p < 0.01, versus corresponding control cells, bp < 0.005 versus corresponding Simvastatin treated cells (two way ANOVA). (d) Pharmaocological Inhibition of PKC pathway diminished simvastatin induced IRS serine phosphorylation. L6 myotubes were cultured in Simvastatin (1 μM) and/or GÖ6983 (1 μM) for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612) and total IRS-1. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4.
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f4: (a) Simvastatin treatment inhibits insulin signaling cascade: L6 myotubes were cultured in Simvastatin for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612, Tyr608) and pAKT. Total IRS-1, AKT and Beta-actin served as loading control. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4. (b) Densitometric quantification results for western blots from Fig. 4A are shown. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal (DMSO) of control cells which was set to 1; a,dp < 0.05 versus DMSO + insulin treated cells, b,cp < 0.005 versus corresponding DMSO treated cells (two way ANOVA). (c) Inhibition of PKC rescues Simvastatin inhibited insulin mediated glucose uptake: Mean basal and insulin stimulated (5 min and 10 min) uptake of 2-NBDG by L6 myotubes treated with Simvastatin (1 μM) and/or PKC inhibitors (Bisindolylmaleimide I, Bis (1 μM) and GÖ6983 (1 μM) for different time points as indicated. DMSO (0.1%) treated cells served as internal control. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal of control cells which was set to 1; **p < 0.01, versus corresponding control cells, bp < 0.005 versus corresponding Simvastatin treated cells (two way ANOVA). (d) Pharmaocological Inhibition of PKC pathway diminished simvastatin induced IRS serine phosphorylation. L6 myotubes were cultured in Simvastatin (1 μM) and/or GÖ6983 (1 μM) for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612) and total IRS-1. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4.

Mentions: Since initial studies showed that simvastatin only affects insulin stimulated glucose uptake but not un-stimulated uptake (Fig. 1) we explored whether the drug may have a direct effect on insulin signaling. Insulin receptor substrate- 1 (IRS-1) plays a key role in transmitting signals from the insulin receptors to intracellular PI3K/Akt pathways. Binding of insulin to its cell-surface receptor triggers the intracellular phosphorylation of Tyr608 in IRS-1 and glucose uptake by Glut-4 transporter translocation. Conversely, inhibition of its phosphorylation of Tyr608 in IRS-1 impedes glucose uptake. To explore simvastatin’s effects on IRS-1 phosphorylation, cells were treated with and without simvastatin and were incubated with insulin for 20 min followed by measurement of IRS-1 phosphorylation at Tyr608 by western blotting. As shown in Fig. 4a, under insulin stimuli, simvastatin treatment significantly inhibited IRS-1 phosphorylation at Tyr608 (~50%) and pAKT (~70%) compared to DMSO treated control cells (Fig. 4b). These data suggest that simvastatin may inhibit insulin mediated glucose uptake by blocking a critical steps in insulin signaling cascade.


Simvastatin may induce insulin resistance through a novel fatty acid mediated cholesterol independent mechanism.

Kain V, Kapadia B, Misra P, Saxena U - Sci Rep (2015)

(a) Simvastatin treatment inhibits insulin signaling cascade: L6 myotubes were cultured in Simvastatin for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612, Tyr608) and pAKT. Total IRS-1, AKT and Beta-actin served as loading control. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4. (b) Densitometric quantification results for western blots from Fig. 4A are shown. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal (DMSO) of control cells which was set to 1; a,dp < 0.05 versus DMSO + insulin treated cells, b,cp < 0.005 versus corresponding DMSO treated cells (two way ANOVA). (c) Inhibition of PKC rescues Simvastatin inhibited insulin mediated glucose uptake: Mean basal and insulin stimulated (5 min and 10 min) uptake of 2-NBDG by L6 myotubes treated with Simvastatin (1 μM) and/or PKC inhibitors (Bisindolylmaleimide I, Bis (1 μM) and GÖ6983 (1 μM) for different time points as indicated. DMSO (0.1%) treated cells served as internal control. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal of control cells which was set to 1; **p < 0.01, versus corresponding control cells, bp < 0.005 versus corresponding Simvastatin treated cells (two way ANOVA). (d) Pharmaocological Inhibition of PKC pathway diminished simvastatin induced IRS serine phosphorylation. L6 myotubes were cultured in Simvastatin (1 μM) and/or GÖ6983 (1 μM) for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612) and total IRS-1. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f4: (a) Simvastatin treatment inhibits insulin signaling cascade: L6 myotubes were cultured in Simvastatin for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612, Tyr608) and pAKT. Total IRS-1, AKT and Beta-actin served as loading control. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4. (b) Densitometric quantification results for western blots from Fig. 4A are shown. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal (DMSO) of control cells which was set to 1; a,dp < 0.05 versus DMSO + insulin treated cells, b,cp < 0.005 versus corresponding DMSO treated cells (two way ANOVA). (c) Inhibition of PKC rescues Simvastatin inhibited insulin mediated glucose uptake: Mean basal and insulin stimulated (5 min and 10 min) uptake of 2-NBDG by L6 myotubes treated with Simvastatin (1 μM) and/or PKC inhibitors (Bisindolylmaleimide I, Bis (1 μM) and GÖ6983 (1 μM) for different time points as indicated. DMSO (0.1%) treated cells served as internal control. Values are shown as mean ± SD after normalizing with the corresponding protein content and expressed relative to basal of control cells which was set to 1; **p < 0.01, versus corresponding control cells, bp < 0.005 versus corresponding Simvastatin treated cells (two way ANOVA). (d) Pharmaocological Inhibition of PKC pathway diminished simvastatin induced IRS serine phosphorylation. L6 myotubes were cultured in Simvastatin (1 μM) and/or GÖ6983 (1 μM) for 48 h, followed by stimulation with insulin for 20 min. Cells were lysed and probed for phosphorylation of IRS-1 (Ser307and Ser612) and total IRS-1. The cropped blots were run under the same experimental conditions. The full-length blots are included in Supplemental Figure 4.
Mentions: Since initial studies showed that simvastatin only affects insulin stimulated glucose uptake but not un-stimulated uptake (Fig. 1) we explored whether the drug may have a direct effect on insulin signaling. Insulin receptor substrate- 1 (IRS-1) plays a key role in transmitting signals from the insulin receptors to intracellular PI3K/Akt pathways. Binding of insulin to its cell-surface receptor triggers the intracellular phosphorylation of Tyr608 in IRS-1 and glucose uptake by Glut-4 transporter translocation. Conversely, inhibition of its phosphorylation of Tyr608 in IRS-1 impedes glucose uptake. To explore simvastatin’s effects on IRS-1 phosphorylation, cells were treated with and without simvastatin and were incubated with insulin for 20 min followed by measurement of IRS-1 phosphorylation at Tyr608 by western blotting. As shown in Fig. 4a, under insulin stimuli, simvastatin treatment significantly inhibited IRS-1 phosphorylation at Tyr608 (~50%) and pAKT (~70%) compared to DMSO treated control cells (Fig. 4b). These data suggest that simvastatin may inhibit insulin mediated glucose uptake by blocking a critical steps in insulin signaling cascade.

Bottom Line: Statins are a class of oral drugs that are widely used for treatment of hypercholesterolemia.We explored the possible mechanism of statin induced insulin resistance using a well-established cell based model and simvastatin as a prototype statin.Our data show that simvastatin induces insulin resistance in a cholesterol biosynthesis inhibition independent fashion but does so by a fatty acid mediated effect on insulin signaling pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India.

ABSTRACT
Statins are a class of oral drugs that are widely used for treatment of hypercholesterolemia. Recent clinical data suggest that chronic use of these drugs increases the frequency of new onset diabetes. Studies to define the risks of statin-induced diabetes and its underlying mechanisms are clearly necessary. We explored the possible mechanism of statin induced insulin resistance using a well-established cell based model and simvastatin as a prototype statin. Our data show that simvastatin induces insulin resistance in a cholesterol biosynthesis inhibition independent fashion but does so by a fatty acid mediated effect on insulin signaling pathway. These data may help design strategies for prevention of statin induced insulin resistance and diabetes in patients with hypercholesterolemia.

No MeSH data available.


Related in: MedlinePlus