GLUT4 and UBC9 protein expression is reduced in muscle from type 2 diabetic patients with severe insulin resistance

TY - JOUR

T1 - GLUT4 and UBC9 protein expression is reduced in muscle from type 2 diabetic patients with severe insulin resistance

AU - Kampmann, Ulla

AU - Christensen, Britt

AU - Nielsen, Thomas Svava

AU - Pedersen, Steen Bønløkke

AU - Ørskov, Lotte

AU - Lund, Sten

AU - Møller, Niels

AU - Jessen, Niels

PY - 2011/11/16

Y1 - 2011/11/16

N2 - Aims: Subgroups of patients with type 2 diabetes mellitus demand large insulin doses to maintain euglycemia. These patients are characterized by severe skeletal muscle insulin resistance and the underlying pathology remains unclear. The purpose of this study was to examine protein expression of the principal glucose transporter, GLUT4, and associated proteins in skeletal muscle from type 2 diabetic patients characterized by severe insulin resistance. Methods: Seven type 2 diabetic patients with severe insulin resistance (mean insulin dose 195 IU/day) were compared with seven age matched type 2 diabetic patients who did not require insulin treatment, and with an age matched healthy control group. Protein expression of GLUT4 and associated proteins was assessed in muscle and fat biopsies using standard western blotting techniques. Results: GLUT4 protein expression was significantly reduced by ~30 pct in skeletal muscle tissue from severely insulin resistant type 2 diabetic subjects, compared with both healthy controls and type 2 diabetic subjects that did not require insulin treatment. In fat tissue, GLUT4 protein expression was reduced in both diabetic groups. In skeletal muscle, the reduced GLUT4 expression in severe insulin resistance was associated with decreased ubiquitin-conjugating enzyme 9 (UBC9) expression while expression of GLUT1, TBC1D1 and AS160 was not significantly different among type 2 diabetic patients and matched controls. Conclusions: Type 2 diabetic patients with severe insulin resistance have reduced expression of GLUT4 in skeletal muscle compared to patients treated with oral antidiabetic drugs alone. GLUT4 protein levels may therefore play a role in the pathology behind type 2 diabetes mellitus among subgroups of patients, and this may explain the heterogeneous response to insulin treatment. This new finding contributes to the understanding of the underlying mechanisms for the development of extreme insulin resistance.

AB - Aims: Subgroups of patients with type 2 diabetes mellitus demand large insulin doses to maintain euglycemia. These patients are characterized by severe skeletal muscle insulin resistance and the underlying pathology remains unclear. The purpose of this study was to examine protein expression of the principal glucose transporter, GLUT4, and associated proteins in skeletal muscle from type 2 diabetic patients characterized by severe insulin resistance. Methods: Seven type 2 diabetic patients with severe insulin resistance (mean insulin dose 195 IU/day) were compared with seven age matched type 2 diabetic patients who did not require insulin treatment, and with an age matched healthy control group. Protein expression of GLUT4 and associated proteins was assessed in muscle and fat biopsies using standard western blotting techniques. Results: GLUT4 protein expression was significantly reduced by ~30 pct in skeletal muscle tissue from severely insulin resistant type 2 diabetic subjects, compared with both healthy controls and type 2 diabetic subjects that did not require insulin treatment. In fat tissue, GLUT4 protein expression was reduced in both diabetic groups. In skeletal muscle, the reduced GLUT4 expression in severe insulin resistance was associated with decreased ubiquitin-conjugating enzyme 9 (UBC9) expression while expression of GLUT1, TBC1D1 and AS160 was not significantly different among type 2 diabetic patients and matched controls. Conclusions: Type 2 diabetic patients with severe insulin resistance have reduced expression of GLUT4 in skeletal muscle compared to patients treated with oral antidiabetic drugs alone. GLUT4 protein levels may therefore play a role in the pathology behind type 2 diabetes mellitus among subgroups of patients, and this may explain the heterogeneous response to insulin treatment. This new finding contributes to the understanding of the underlying mechanisms for the development of extreme insulin resistance.

KW - Blotting, Western

KW - Case-Control Studies

KW - Diabetes Mellitus, Type 2

KW - Female

KW - Glucose Transporter Type 4

KW - Humans

KW - Insulin Resistance

KW - Male

KW - Middle Aged

KW - Muscle, Skeletal

KW - RNA, Messenger

KW - Real-Time Polymerase Chain Reaction

KW - Reverse Transcriptase Polymerase Chain Reaction

KW - Ubiquitin-Conjugating Enzymes

U2 - 10.1371/journal.pone.0027854

DO - 10.1371/journal.pone.0027854

M3 - Journal article

C2 - 22114711

SN - 1932-6203

VL - 6

SP - e27854

JO - PLOS ONE

JF - PLOS ONE

IS - 11

ER -