Calcineurin is an important factor involved in glucose uptake in human adipocytes

Ana Catarina R G Fonseca,Maria J Pereira,Eugénia Carvalho,Jan W Eriksson

doi:10.1007/s11010-017-3261-0

Abstract

Calcineurin inhibitors are used in immunosuppressive therapy applied after transplantation, but they are associated with major metabolic side effects including the development of new onset diabetes. Previously, we have shown that the calcineurin inhibiting drugs tacrolimus and cyclosporin A reduce adipocyte and myocyte glucose uptakes by reducing the amount of glucose transporter type 4 (GLUT4) at the cell surface, due to an increased internalization rate. However, this happens without alteration in total protein and phosphorylation levels of key proteins involved in insulin signalling or in the total amount of GLUT4. The present study evaluates possible pathways involved in the altered internalization of GLUT4 and consequent reduction of glucose uptake provoked by calcineurin inhibitors in human subcutaneous adipose tissue. Short- and long-term treatments with tacrolimus, cyclosporin A or another CNI deltamethrin (herbicide) decreased basal and insulin-dependent glucose uptake in adipocytes, without any additive effects observed when added together. However, no tacrolimus effects were observed on glucose uptake when gene transcription and protein translation were inhibited. Investigation of genes potentially involved in GLUT4 trafficking showed only a small effect on ARHGEF11 gene expression (p < 0.05). In conlusion, the specific inhibition of calcineurin, but not that of protein phosphatases, decreases glucose uptake in human subcutaneous adipocytes, suggesting that calcineurin is an important regulator of glucose transport. This inhibitory effect is mediated via gene transcription or protein translation; however, expression of genes potentially involved in GLUT4 trafficking and endocytosis appears not to be involved in these effects.

Highlights

The International Diabetes Federation has shown that the number of people with type 2 diabetes is increasing worldwide
The long-term incubation of adipocytes with cyclosporin A (100 nM), another calcineurin inhibitor, induced a very similar decrease in glucose uptake compared with tacrolimus (Fig. 2c)
The specific inhibition of calcineurin by tacrolimus, cyclosporin A and deltamethrin, but not the inhibition of other protein phosphatases 1, 2A and phosphorylated myosin light-chain, reduced glucose uptake in subcutaneous adipocytes, suggesting that calcineurin plays an important role in glucose uptake in human, as well as in rodent adipocytes, as previously described [8, 39]

Summary

Introduction

The International Diabetes Federation has shown that the number of people with type 2 diabetes is increasing worldwide. In 2014, there were about 400 million individuals with diabetes mellitus, and this number is expected to increase to approx. Calcineurin has been implicated in a variety of biological responses, including lymphocyte activation and cardiovascular and skeletal muscle development [3]. Since their introduction, calcineurin inhibitors have become the cornerstone of immunosuppressive therapy in solid organ transplantation. Calcineurin inhibitors have become the cornerstone of immunosuppressive therapy in solid organ transplantation They are associated with the development of cardiovascular and metabolic complications, like dyslipidemia, hypertension and diabetes melitus [4].

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