Effects of Inhibition of Serine Palmitoyltransferase SPT and Sphingosine Kinase 1 SphK1 on Palmitate Induced Insulin Resistance in L6 MyotubesReportar como inadecuado




Effects of Inhibition of Serine Palmitoyltransferase SPT and Sphingosine Kinase 1 SphK1 on Palmitate Induced Insulin Resistance in L6 Myotubes - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Background

The objective of this study was to examine the effects of short 2 h and prolonged 18 h inhibition of serine palmitoyltransferase SPT and sphingosine kinase 1 SphK1 on palmitate PA induced insulin resistance in L6 myotubes.

Methods

L6 myotubes were treated simultaneously with either PA and myriocin SPT inhibitor or PA and Ski II SphK1inhibitor for different time periods 2 h and 18 h. Insulin stimulated glucose uptake was measured using radioactive isotope. Expression of insulin signaling proteins was determined using Western blot analyses. Intracellular sphingolipids content sphinganine SFA, ceramide CER, sphingosine SFO, sphingosine-1-phosphate S1P were estimated by HPLC.

Results

Our results revealed that both short and prolonged time of inhibition of SPT by myriocin was sufficient to prevent ceramide accumulation and simultaneously reverse palmitate induced inhibition of insulin-stimulated glucose transport. In contrast, prolonged inhibition of SphK1 intensified the effect of PA on insulin-stimulated glucose uptake and attenuated further the activity of insulin signaling proteins pGSK3β-GSK3β ratio in L6 myotubes. These effects were related to the accumulation of sphingosine in palmitate treated myotubes.

Conclusion

Myriocin is more effective in restoration of palmitate induced insulin resistance in L6 myocytes, despite of the time of SPT inhibition, comparing to SKII a specific SphK1 inhibitor. Observed changes in insulin signaling proteins were related to the content of specific sphingolipids, namely to the reduction of ceramide. Interestingly, inactivation of SphK1 augmented the effect of PA induced insulin resistance in L6 myotubes, which was associated with further inhibition of insulin stimulated PKB and GSK3β phosphorylation, glucose uptake and the accumulation of sphingosine.



Autor: Agnieszka Mikłosz , Bartłomiej Łukaszuk, Marcin Baranowski, Jan Górski, Adrian Chabowski

Fuente: http://plos.srce.hr/



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